I824.01 Sys 824 Reference Manual.book

I824.01 Sys 824 Reference Manual.book
Model 824
Precision Sound Level Meter
& Real Time Analyzer
Reference Manual
Larson Davis
Model 824
Technical Reference Manual
I824.01 Rev Q
Copyright
Copyright 2017 by PCB Piezotronics, Inc. This manual is copyrighted, with all rights reserved. The
manual may not be copied in whole or in part for any use without prior written consent of PCB
Piezotronics, Inc.
Disclaimer
The following paragraph does not apply in any state or country where such statements are not
agreeable with local law:
Even though PCB Piezotronics, Inc. has reviewed its documentation, PCB Piezotronics Inc. makes no
warranty or representation, either expressed or implied, with respect to this instrument and
documentation, its quality, performance, merchantability, or fitness for a particular purpose. This
documentation is subject to change without notice, and should not be construed as a commitment or
representation by PCB Piezotronics, Inc.
This publication may contain inaccuracies or typographical errors. PCB Piezotronics, Inc. will
periodically update the material for inclusion in new editions. Changes and improvements to the
information described in this manual may be made at any time.
Record of Serial Number and Purchase Date
Model 824
Serial Number: ___________
PRM902 Preamplifier
Serial Number: ___________
Microphone Model: _________
Serial Number: ___________
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PCB Piezotronics, Inc. is an environmentally friendly organization and encourages our customers to
be environmentally conscious. When this product reaches its end of life, please recycle the product
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Warranty
For warranty information, refer to our Terms and Conditions of Sale on our website,
www.larsondavis.com/TermsConditions.aspx.
Chapter 1
Introduction
1-1
About This Manual .................................................................................................1-1
Special Features of the Electronic Version ........................................................1-1
Bookmarks .........................................................................................................1-1
Opening Bookmarks......................................................................................1-1
Closing Bookmarks .......................................................................................1-2
Expanding Bookmarks ..................................................................................1-2
Click to Display Page....................................................................................1-3
Return to Previous View ...............................................................................1-3
Links...................................................................................................................1-3
Click to Display Page....................................................................................1-3
About This Chapter.................................................................................................1-4
Formatting...............................................................................................................1-4
Features ...................................................................................................................1-5
Hardware Features .............................................................................................1-5
System 824 Components....................................................................................1-8
System Diagram ...............................................................................................1-11
Getting Started ......................................................................................................1-12
Unpacking and Inspection................................................................................1-12
Comments concerning the Digital Signal Processor ...................................1-12
Accessories and Optional Equipment ..............................................................1-14
Connecting Internal or External Power............................................................1-16
Using the NiMH Battery Pack ....................................................................1-16
Using Alkaline Batteries or Individual NiMH rechargable cells. ...............1-17
Using the AC Power Adapter......................................................................1-18
Chapter 2
Overview
2-1
System 824 Setups or Instrument Definitions ........................................................2-1
Instrument Definition (ID) Types ..........................................................................2-2
Write Protect, Delete, Write Enable IDs............................................................2-2
SLM&RTA (SSA) .............................................................................................2-2
SLM (ISM) ........................................................................................................2-4
Logging (LOG) ..................................................................................................2-4
Selecting a Measurement Setup ..............................................................................2-6
Performing a Measurement; SLM&RTA (SSA) ....................................................2-7
Stop, Pause and Back Erase Functions ..............................................................2-8
Stopping and Starting Measurements............................................................2-8
Pausing Measurements..................................................................................2-8
Back Erasing .................................................................................................2-8
Changing the detector of the displayed SPL value ............................................2-8
Changing the frequency weighting of the displayed SPL value ........................2-9
Changing the displayed secondary parameter..................................................2-10
Changing the frequency weighting of the displayed Lpeak value ...................2-10
Changing the amplitude range, or input Gain ..................................................2-10
Views ....................................................................................................................2-11
Selecting a VIEW.............................................................................................2-11
Data Storage and Recall........................................................................................2-13
Storing Data.................................................................................................2-13
Recalling Data .............................................................................................2-13
Calibration ............................................................................................................2-14
Correction of Calibrator Output Level.............................................................2-17
Chapter 3
Front Panel Keys; Functions and Menus
3-1
v Power Key .........................................................................................................3-3
Power-up the Instrument / Viewing PWR Display ............................................3-3
Power Settings....................................................................................................3-5
Extra Notes on Power Conservation ..................................................................3-8
s Run/Stop Key ....................................................................................................3-8
R Reset Key ..........................................................................................................3-9
p Pause Key ........................................................................................................3-10
Pause............................................................................................................3-10
Pause, Back Erase .......................................................................................3-10
Preview........................................................................................................3-10
lrud Arrow Keys .................................................................................3-11
c Check Key........................................................................................................3-11
V View Key.........................................................................................................3-12
D Data Key..........................................................................................................3-12
S Setup Key ........................................................................................................3-14
Save ID........................................................................................................3-15
Title .............................................................................................................3-15
ID Name ......................................................................................................3-16
Write Protect, Delete, Write Enable IDs..........................................................3-17
TTools Key .........................................................................................................3-18
About................................................................................................................3-20
Calibration........................................................................................................3-22
Clock/Timer .....................................................................................................3-23
Memory ............................................................................................................3-27
Deleting Stored Data ........................................................................................3-29
Delete Last Function ...................................................................................3-29
824 Memory Structure ................................................................................3-29
Deleting the Last Stored Record .................................................................3-29
Deleting Individual Records........................................................................3-31
Power Monitor .................................................................................................3-32
Communication ................................................................................................3-33
P Print Key..........................................................................................................3-37
Chapter 4
Quick Start
4-1
Turning On and Calibrating the System 824 ..........................................................4-1
High Range Calibration .....................................................................................4-4
Taking Measurements and Storing Data.................................................................4-5
SLM&RTA Measurements ................................................................................4-5
Viewing RTA Displays during a Measurement .................................................4-7
Recalling Stored Data .............................................................................................4-9
Selecting and Modifying Instrument Definitions (IDs) ........................................4-11
The Setup Menu ...............................................................................................4-11
The Active ID...................................................................................................4-12
Menu Scrolling.................................................................................................4-13
Permanent IDs..................................................................................................4-14
Write-protected IDs..........................................................................................4-14
Preparing for a Measurement ...........................................................................4-15
Selecting a Different ID ...................................................................................4-15
Accessing the Settings Menu ...........................................................................4-15
Accessing the Settings Menu to Initiate Editing or Modification....................4-17
Setting Control in the SLM View ....................................................................4-20
Chapter 5
System 824 Views
5-1
Status Icons and Indicators .....................................................................................5-1
General Views.........................................................................................................5-4
SLM Views ........................................................................................................5-4
Any Data View...................................................................................................5-7
Any Level Format .........................................................................................5-7
Any Impulse Format......................................................................................5-8
Any Time Format ..........................................................................................5-8
SSA Specific Views................................................................................................5-9
SSA Displays ...................................................................................................5-11
SSA Displays Including 1/1 or 1/3 Octave Spectral Data...........................5-11
Tabular SSA Views.....................................................................................5-11
Time History Displays ................................................................................5-12
SSA Intervals...............................................................................................5-13
SSA Time History .......................................................................................5-15
Run Log.......................................................................................................5-18
Ln Centiles ..................................................................................................5-19
Logging SLM Specific Views ..............................................................................5-23
Current SLM and Overall SLM Views ............................................................5-25
Current SLM/Overall SLM Display-a (SPL) ..............................................5-26
Current/Overall SLM Display-b (Times)....................................................5-27
Current/Overall SLM Display-c (Min/Max) ...............................................5-28
Current/Overall SLM Display-d (Peaks).....................................................5-29
Current/Overall SLM Display-e (TWA) .....................................................5-30
Exposure Views ...............................................................................................5-31
Exposure Display-a .....................................................................................5-31
Exposure-b Display .....................................................................................5-33
Exposure-c Display .....................................................................................5-34
Ln Centiles Views............................................................................................5-35
Ln-a Display................................................................................................5-35
Ln-b Display................................................................................................5-36
Stats Views.......................................................................................................5-37
Stats-a Display.............................................................................................5-37
Stats-b Display ............................................................................................5-38
Stats-c Display.............................................................................................5-39
Run Log (LOG & SSA) ...................................................................................5-40
Time History ....................................................................................................5-41
Single Other Level ......................................................................................5-43
Multiple Other Levels .................................................................................5-43
Intervals............................................................................................................5-44
Intervals-a Display ......................................................................................5-44
Intervals-b Display ......................................................................................5-45
Intervals-c Display ......................................................................................5-47
Intervals-d Display ......................................................................................5-48
Intervals-e Display ......................................................................................5-49
Intervals-f Display.......................................................................................5-50
Exceedance History..........................................................................................5-51
Excd-a Display ............................................................................................5-52
Excd-b Display............................................................................................5-53
Excd-c Display ............................................................................................5-54
Excd Time History Display.........................................................................5-55
Daily Views......................................................................................................5-57
Daily-a Display ...........................................................................................5-57
Daily-b Display ...........................................................................................5-59
Daily-c Wind Display..................................................................................5-60
Daily-d Windy Percent Display ..................................................................5-62
Hourly Leq Display.....................................................................................5-63
Metrics .............................................................................................................5-65
Metrics-a Display ........................................................................................5-65
Metrics-b Display........................................................................................5-66
PassBy ..............................................................................................................5-67
Wind/Tach........................................................................................................5-68
Wind-a Display ...........................................................................................5-69
Wind-b Display ...........................................................................................5-70
Wind-c Percent Display ..............................................................................5-71
Chapter 6
System 824 Virtual Instruments
6-1
System 824 Virtual Instruments .............................................................................6-1
Selecting an Instrument ID .....................................................................................6-3
Sound Spectrum Analyzer (SSA) ...........................................................................6-3
SSA Measuring Ranges .....................................................................................6-4
LN Percentiles (Spectral) ...................................................................................6-5
AC/DC Output ...................................................................................................6-5
Logging SLM..........................................................................................................6-7
Time History ......................................................................................................6-7
Interval History ..................................................................................................6-7
Exceedances .......................................................................................................6-8
LN Percentiles (Broadband)...............................................................................6-8
Sound Exposure .................................................................................................6-8
LOG and ISM Measuring Ranges......................................................................6-9
Chapter 7
Using ID Setting Files
7-1
Recalling ID Setting Files.......................................................................................7-1
Customizing Settings ..............................................................................................7-2
Settings Example - SLM&RTA (SSA) ..............................................................7-2
Settings Descriptions ..............................................................................................7-4
Common SLM Settings......................................................................................7-5
Title Setting - (SSA, LOG, ISM)....................................................................7-5
Detector Setting - (SSA, LOG, ISM)..............................................................7-5
Weighting Setting - (SSA, LOG, ISM)...........................................................7-6
Gain Setting - (SSA) ......................................................................................7-6
Range Setting - (LOG, ISM)..........................................................................7-7
Transducer Setting - (SSA, LOG, ISM) .........................................................7-8
Random Incidence Microphone Correction - (Available to all Instrument
types) .............................................................................................................7-8
Pk Weighting - (SSA, LOG, ISM)..................................................................7-9
RTA Detector Setting - (SSA) ......................................................................7-9
RTA Weighting - (SSA).................................................................................7-9
Bandwidth Setting - (SSA)...........................................................................7-10
Common Control Settings................................................................................7-10
Control Settings - (ISM)..............................................................................7-10
Control Settings _(SSA, LOG)....................................................................7-10
AC/DC Output Settings - (SSA, LOG, ISM)................................................7-12
Logic Input Setting - (SSA, LOG, ISM).......................................................7-12
Logic Output Setting - (SSA, LOG, ISM) ....................................................7-13
Logic Output Time Setting - (SSA, LOG, ISM)...........................................7-15
Logic Output #2 ..........................................................................................7-16
Logic Output #2 Time Setting.....................................................................7-16
Heater On ....................................................................................................7-16
E. A. Cal Tone.............................................................................................7-16
Logging SLM TWA Settings...........................................................................7-16
Ovll Exchange - (LOG) ...............................................................................7-17
Ovll Threshold - (LOG)...............................................................................7-18
Ovll Criterion - (LOG) ................................................................................7-18
Criterion Time - (LOG) ...............................................................................7-19
Crnt Exchange - (SSA, ISM, LOG) .............................................................7-19
Crnt Threshold (SSA, ISM, LOG) ..............................................................7-19
Crnt Criterion (LOG) ..................................................................................7-20
LOG and SSA Ln Settings ...............................................................................7-20
Enable Ln ....................................................................................................7-21
Start Level ...................................................................................................7-21
Ln’s .............................................................................................................7-21
Spectral Ln’s (SSA only) ............................................................................7-22
LOG and SSA Triggering Settings ..................................................................7-22
SPL Excd Lvl 1 - (LOG, SSA).....................................................................7-23
SPL Excd Lvl 2 - (LOG, SSA).....................................................................7-23
PK Excd Lvl 1 - (LOG, SSA).......................................................................7-24
Pk Excd Lvl 2 - (LOG, SSA) .......................................................................7-24
Hysteresis - (LOG, SSA)..............................................................................7-24
LOG and SSA Wind/Tach Settings .................................................................7-25
Setup of Wind/Tach Function .....................................................................7-25
Wind Scale ..................................................................................................7-27
Wind Units ..................................................................................................7-27
Direction Units ............................................................................................7-27
Wind/Tach Enable.......................................................................................7-28
Windy Threshold.........................................................................................7-28
Wind Exceedance Level..............................................................................7-28
Windy Hysteresis ........................................................................................7-29
Wind Pause Enable......................................................................................7-29
Pulse Trigger Voltage..................................................................................7-29
Pulse Source ................................................................................................7-29
LOG and SSA Time History Settings ..............................................................7-30
Hist Enable - (LOG, SSA)............................................................................7-32
Hist Period (LOG, SSA)...............................................................................7-32
Period Units - (LOG, SSA) ..........................................................................7-32
Other Level - (LOG only)............................................................................7-33
Resolution - (LOG, SSA) .............................................................................7-34
Advanced Time History - (LOG, SSA).......................................................7-34
Marker Text - (LOG, SSA) .........................................................................7-35
LOG and SSA Interval Settings .......................................................................7-35
Intv Enable - (LOG, SSA)............................................................................7-36
Intv Period - (LOG, SSA).............................................................................7-37
Intv Time Sync - (LOG, SSA)......................................................................7-37
Intv Save Ln’s - (LOG, SSA)......................................................................7-37
Intv Auto Stop - (LOG, SSA).......................................................................7-38
Intv Threshold - (LOG, SSA).......................................................................7-38
Intv Exchange - (LOG, SSA) .......................................................................7-38
Intv Spectrum - (SSA only).........................................................................7-39
Logging SLM Exceedance History Settings....................................................7-39
Triggering - (LOG)......................................................................................7-39
Excd Enable - (LOG)...................................................................................7-40
Min Duration - (LOG) .................................................................................7-40
Excd Time Hist - (LOG)..............................................................................7-40
T.H. Period - (LOG) ....................................................................................7-40
Excd Trigger - (LOG)..................................................................................7-40
Excd Time - (LOG) .....................................................................................7-41
Timed Excd Period - (LOG)........................................................................7-41
Daily Enable - (LOG)..................................................................................7-41
Daily Ln’s - (LOG)......................................................................................7-42
Logging SLM Define Report Settings .............................................................7-42
Data Report - (LOG, SSA) ...........................................................................7-43
Setup Report - (LOG, SSA) ........................................................................7-43
SPL Histogram - (LOG) ..............................................................................7-43
Pk-1 Histogram - (LOG) .............................................................................7-43
Pk-2 Histogram - (LOG) .............................................................................7-44
Intv Report - (LOG, SSA) ............................................................................7-44
Hist Report - (LOG, SSA)............................................................................7-44
Menu Layout of SSA Settings ..............................................................................7-45
Menu Layout of Integrating SLM (ISM) Settings ................................................7-48
Menu Layout of Logging SLM Settings...............................................................7-50
Advanced Menu Layout........................................................................................7-54
Check Menus ........................................................................................................7-57
Check Menu Example......................................................................................7-58
SLM Check Menu Options (SSA and LOG) ...................................................7-60
Mark Display...............................................................................................7-60
Graph Menu.................................................................................................7-61
Settings ........................................................................................................7-62
Controls Settings Menu...............................................................................7-62
Other SSA Check Menus .................................................................................7-63
Any Data Check Menu................................................................................7-63
RTA Check Menu .......................................................................................7-63
Intervals Check Menu .................................................................................7-64
Time History Check Menu..........................................................................7-65
Run Log Check Menu .................................................................................7-66
Ln Centiles Check Menus ...........................................................................7-67
Other Logging (LOG) Check Menus ...............................................................7-69
Any Data Check Menu................................................................................7-69
Current SLM / Overall SLM Check Menu..................................................7-70
Exposure Check Menu ................................................................................7-70
LN Centiles Check Menu............................................................................7-71
Stats Check Menu........................................................................................7-71
Run Log Check Menu .................................................................................7-72
Time History Check Menu..........................................................................7-72
Intervals Check Menu .................................................................................7-73
Excd History Check Menu ..........................................................................7-73
Daily History Check Menu .........................................................................7-74
Chapter 8
Printing a Report
8-1
Connecting the 824 to a Serial Printer ....................................................................8-1
Printing Reports ......................................................................................................8-2
Defining and Printing Tailored Reports..................................................................8-4
Using the Recall Format (SSA and LOG instruments only)..............................8-7
Default Settings Values for the Recall Format Reports ................................8-8
Printing a Custom Report .....................................................................................8-23
Chapter 9
Performing a Sound Level Measurement
9-1
Configuration of the System ...................................................................................9-1
Selecting a Measurement Mode..............................................................................9-1
Selecting a Measurement ID ..............................................................................9-2
Editing the Microphone Parameters .......................................................................9-3
Calibration ..............................................................................................................9-3
Entering the Noise Floor Values.............................................................................9-4
Editing the Measurement Parameters .....................................................................9-5
Positioning the Meter..............................................................................................9-7
Use of a Windscreen ..........................................................................................9-7
Selecting the SLM Display .....................................................................................9-9
Selecting the Measurement Range..........................................................................9-9
ISM and LOG Modes.........................................................................................9-9
Selecting the Range Setting.........................................................................9-10
SSA Mode ........................................................................................................9-10
Performing a Measurement...................................................................................9-11
Averaging Time ...............................................................................................9-12
Linearity Range.....................................................................................................9-12
Overload and Under Range Conditions ................................................................9-13
Overload Condition..........................................................................................9-13
Reset ............................................................................................................9-14
Under Range Condition ...................................................................................9-14
Max, Min and Peak Values...................................................................................9-14
Measuring for a Preset Integration Time ..............................................................9-15
Timer Mode......................................................................................................9-15
Measuring using User-Selectable Thresholds.......................................................9-16
Chapter 10 Using the 824 Utility Software
10-1
824 Utility Installation ..........................................................................................10-1
Starting the 824 Utility Software ..........................................................................10-2
Connecting to Your Computer..............................................................................10-2
824 Utility Tool Bar..............................................................................................10-4
824 Utility Setup Window ....................................................................................10-6
Retrieving setups from the 824 ........................................................................10-7
Modifying and Storing Setups to the 824 ........................................................10-9
Changing System Settings...........................................................................10-9
Manipulating a Setup ................................................................................10-10
Saving Setups to Disk Files ...........................................................................10-12
Opening Setup Disk Files ..............................................................................10-12
Creating a New Setup ....................................................................................10-14
Renaming an Existing Setup ..........................................................................10-15
Deleting an Existing Setup.............................................................................10-16
Locking and Unlocking Setups ......................................................................10-17
Downloading Measurement Data .......................................................................10-17
Specifying a Destination File.........................................................................10-18
Changing the Download File Name...............................................................10-20
Adding Notes to a download file ...................................................................10-21
Selecting Active Measurements or Data Files ...............................................10-21
Downloading the Measurement .....................................................................10-22
Explanation of files in the 824 Utility Directory ...........................................10-24
Translating Data from a Downloaded Binary File..............................................10-25
Selecting a Data set to view ...........................................................................10-27
Printing a Translated File ...............................................................................10-29
Viewing a Translated File Within a Spreadsheet Program ............................10-31
Additional Features.............................................................................................10-32
Chapter 11 RTA (optional)
11-1
Settings Menu .......................................................................................................11-1
Settings Descriptions ............................................................................................11-5
RTA Settings Menu .........................................................................................11-5
Autostore Settings Menu..................................................................................11-7
Arm Settings Menu ..........................................................................................11-8
Trigger Settings Menu ...................................................................................11-10
End Settings Menu .........................................................................................11-11
Then Settings Menu .......................................................................................11-12
Trigger Settings Menu (continued) ................................................................11-13
RT60 Reverberation Time Settings................................................................11-14
RT60-A and RT60-B Instrument Definition..................................................11-15
Qualifying Background Noise: Rooms [RTA] ID .........................................11-16
Display Views.....................................................................................................11-17
RTA Views ....................................................................................................11-17
Trigger Views ................................................................................................11-20
Autostore Views.............................................................................................11-22
Autostore ByTime Spectral History...............................................................11-26
ByTime Spectrum Check Menu.....................................................................11-27
ByTime Graph Check Menu ..........................................................................11-28
RT-60 .............................................................................................................11-30
RT60 Check Menu .........................................................................................11-31
Spatial Avg Views .........................................................................................11-32
Spatial Avg Check Menu ...............................................................................11-34
Avg History Check Menu ..............................................................................11-35
Rooms Views .................................................................................................11-36
Chapter 12 FFT (Optional)
12-1
Features .................................................................................................................12-1
Settings Menu .......................................................................................................12-1
Settings Descriptions ............................................................................................12-3
FFT Display ..........................................................................................................12-6
FFT...................................................................................................................12-6
FFT Check Menu .............................................................................................12-8
THD (Total Harmonic Distortion) ........................................................................12-8
THD Check Menu ..........................................................................................12-10
Snapshot..............................................................................................................12-10
Snapshot Check Menu ...................................................................................12-11
FFT Calibration...................................................................................................12-12
Calibrating dB to a Different Reference ........................................................12-12
Displaying Amplitude in Linear Units...........................................................12-13
Setup of Linear Units Readout. .................................................................12-14
Frequently Asked Questions Concerning FFT...............................................12-16
Chapter 13 AUD (Optional)
13-1
Connecting the Test System .................................................................................13-2
Selecting the 824-AUD Operation Mode .............................................................13-3
Microphone Sensitivity Calibration......................................................................13-4
AUD Modes ..........................................................................................................13-4
View Menu.......................................................................................................13-5
SLM/RTA Submenu ...................................................................................13-5
FFT Submenu..............................................................................................13-5
Pulse/FM Submenu .....................................................................................13-5
Display Sequence .............................................................................................13-5
SLM+RTA Live Display .................................................................................13-6
SLM+RTA Live Check Menu.....................................................................13-7
Any Level -a, -b and -c Displays .....................................................................13-8
Any Level Check Menu ..............................................................................13-9
Linearity RTA Display.....................................................................................13-9
Manual Lock .............................................................................................13-11
Automatic Lock.........................................................................................13-12
Linearity RTA Check Menu......................................................................13-13
Linearity FFT Display....................................................................................13-13
Manual Lock .............................................................................................13-15
Automatic Lock.........................................................................................13-15
Linearity FFT Check Menu.......................................................................13-16
Flatness FFT Display .....................................................................................13-17
THD Display ..................................................................................................13-18
THD Check Menu .....................................................................................13-20
Pulse/FM Display...........................................................................................13-20
Pulse/FM-a Display...................................................................................13-21
Pulse/FM-b Display...................................................................................13-23
Pulse/FM Check Menu..............................................................................13-23
FFT Display ........................................................................................................13-24
FFT Check Menu ......................................................................................13-24
Appendix A Serial Port Interface Remote Control
A-1
Interface Cables .....................................................................................................A-1
Connection to a computer using CBL006 ....................................................A-2
‘Daisy Chain Addressing .......................................................................................A-3
824 Network, Addressing Commands ..............................................................A-3
Commands .............................................................................................................A-4
Remote Control Commands (Detailed) .................................................................A-5
Mode Commands ..............................................................................................A-5
“Read” Commands (Reads out data variables) .................................................A-7
“ANY DATA” READ COMMANDS ............................................................A-21
Other Read Commands ...................................................................................A-23
Group Read Programming ..............................................................................A-24
Setting Commands ...............................................................................................A-25
Querying Settings............................................................................................A-25
Ln Query Commands (SSA) ...........................................................................A-27
Entering Settings .............................................................................................A-27
Option Settings...........................................................................................A-27
Numeric Settings ........................................................................................A-29
Character String Settings............................................................................A-29
Template Settings.......................................................................................A-29
Setting List ...........................................................................................................A-31
Histogram Reports ..........................................................................................A-38
Tailored Report ..........................................................................................A-39
Miscellaneous.............................................................................................A-39
Error Checking I/O..........................................................................................A-42
RTA Settings Commands................................................................................A-45
History Records...............................................................................................A-47
Types of History.........................................................................................A-48
Advance......................................................................................................A-48
Backup........................................................................................................A-49
Find.............................................................................................................A-49
History Data Variables.........................................................................................A-49
Exceedance History Variables ........................................................................A-49
Interval History Variables (“I” Commands) ...................................................A-51
Daily History Variables - (D1-D102) ............................................................A-56
Run Log Variables (SSA, ISM, LOG, TAL) ..................................................A-58
Calibration History Variables (LOG) .............................................................A-58
Time History Variables (SSA, LOG, TAL) ....................................................A-59
Time History Variables (SSA, LOG, TAL) ....................................................A-60
Histogram Table Variables .............................................................................A-60
Print Command ....................................................................................................A-61
Error Messages and Warnings .............................................................................A-63
Modem Control Mode (All Instruments).............................................................A-66
Modem Mode ..................................................................................................A-66
Dial Out Mode ................................................................................................A-66
Monitor Number .............................................................................................A-67
824 Phone Dialing Procedure .........................................................................A-67
Model 824 Answering Procedure ...................................................................A-68
Unsupported Miscellaneous Commands .............................................................A-69
Data File Commands ...........................................................................................A-70
Keyboard Simulation ...........................................................................................A-72
Operation Notes ...................................................................................................A-73
Appendix B Integrated Level Calculations
B-1
Appendix C Technical Specifications
C-1
Declaration of Conformity ................................................................................ C-1
1/1 and 1/3 Octave Filters ............................................................................... C-20
Frequency Range........................................................................................ C-20
Filter Shapes:.............................................................................................. C-20
Frequency Response ....................................................................................... C-24
Power/Current Draw of 824 Using External Power........................................ C-49
Appendix D Glossary
D-1
Allowed Exposure Time (Ti) .......................................................................D-1
Average Sound Level (Lavg) .......................................................................D-1
Community Noise Equivalent Level (CNEL, Lden)....................................D-2
Criterion Duration (Tc) ................................................................................D-3
Criterion Sound Exposure (CSE) .................................................................D-3
Criterion Sound Level (Lc) ..........................................................................D-3
Daily Personal Noise Exposure (LEP,d) ......................................................D-3
Day-Night Average Sound Level (DNL, Ldn).............................................D-3
Decibel (dB) .................................................................................................D-4
Department of Defense Level (LDOD)........................................................D-8
Dose..............................................................................................................D-8
Detector ........................................................................................................D-8
Eight Hour Time-Weighted Average Sound Level (L TWA(8)).................D-8
Energy Equivalent Sound Level (Leq).........................................................D-8
Exchange Rate (Q), Exchange Rate Factor (q), Exposure Factor (k) ..........D-8
Far Field .......................................................................................................D-9
Free Field......................................................................................................D-9
Frequency (Hz, rad/sec) ...............................................................................D-9
Frequency Band Pass Filter........................................................................D-10
Frequency Filter - Weighted ......................................................................D-10
Leq..............................................................................................................D-12
Level (dB) ..................................................................................................D-12
Measurement Duration (T).........................................................................D-12
Microphone Guidelines ..............................................................................D-12
Near Field...................................................................................................D-15
Noise...........................................................................................................D-15
Noise Dose (D)...........................................................................................D-16
Noise Exposure ..........................................................................................D-17
OSHA Level (LOSHA)..............................................................................D-17
Preamplifier................................................................................................D-17
Projected Noise Dose .................................................................................D-17
Single Event Noise Exposure Level (SENEL, LAX) ................................D-17
Sound..........................................................................................................D-17
Sound Exposure (SE) .................................................................................D-18
Sound Exposure Level (SEL, LET) ...........................................................D-18
Sound Pressure ...........................................................................................D-19
Sound Pressure Level (SPL, Lp) ................................................................D-20
Sound Power(W) ........................................................................................D-21
Sound Power Level (PWL, Lw).................................................................D-21
Sound Speed, (c,) .......................................................................................D-22
Spectrum (Frequency Spectrum)................................................................D-22
Threshold Sound Level (Lt) .......................................................................D-22
Time Weighted Average Sound Level (TWA, LTWA(TC)) .....................D-22
Time Weighting..........................................................................................D-23
Vibration.....................................................................................................D-23
Wavelength (l)............................................................................................D-23
Wavenumber (k).........................................................................................D-23
Appendix E Memory Usage
E-1
LOG Memory Usage ............................................................................................. E-1
Exceedance Records (Exceedance History Enabled)] ...................................... E-1
Interval Records (Intv History Enabled) ........................................................... E-2
Daily Records (Daily History Enabled) ............................................................ E-2
Time History Records (Time History Enabled) ................................................ E-2
Other Histories and Memory Usage.................................................................. E-2
Estimating Memory Usage: .............................................................................. E-3
824-LOG Memory Usage Worksheet ............................................................... E-5
824-SSA Memory Usage ....................................................................................... E-7
Interval Records (Intv History Enabled) ........................................................... E-7
Time History Records (Time History Enabled) ................................................ E-8
Appendix F SLM Testing to IEC61672-1
F-1
Reference Sound Pressure Level:................................................................. F-1
Reference Level Range: ............................................................................... F-1
Microphone Reference Point:....................................................................... F-1
Average Frequency Response Corrections .................................................. F-2
Periodic Testing of A-Weighted Sound Levels............................................ F-4
A-Weighted Sound Levels at Upper and Lower Limits of the Linear Operating
Range............................................................................................................ F-5
Electrical Signal Input Device..................................................................... :F-5
Inherent Noise: ............................................................................................. F-5
Maximum Sound Pressure Level: ................................................................ F-6
Power Supply Voltage Range: ..................................................................... F-6
Display Device ............................................................................................. F-6
Stabilization Time Following Changes of Environmental Conditions: ....... F-6
Electric Field Strength Above 10 V/m:........................................................ F-6
Greatest Radio Frequency Emission Levels: ............................................... F-6
Effect of Electrostatic Discharges ................................................................ F-7
Greatest Susceptibility to AC Power and Radio Frequency Fields:............. F-7
...................................................................................................................... F-7
Appendix G Miscellaneous Information
G-1
CHAPTER
1
Introduction
Welcome to the Larson Davis LxT. This versatile
instrument, with graphic display, performs the functions of
several instruments. It puts the combined features of a
precision sound level meter and a real-time frequency
analyzer in the palm of your hand.
About This Manual
Special Features of the Electronic Version
There are a variety of special techniques for navigating
through pdf documents which can greatly simplify finding
specific items in this manual. Two of these, bookmarks and
links, are discussed below.
Bookmarks
Opening Bookmarks
Bookmarks are clickable navigation tools in pdf files. To
open bookmark, left click the upper Tab on the left of the
screen labeled Bookmarks. These will appear as shown
below.
2/6/17
Introduction
1-1
In the unexpanded view, bookmarks lists the names and page
numbers of chapters and appendixes in order of appearance,
as well as the Table of Contents and the Index.
Closing Bookmarks
To close bookmarks, simply left click the tab once more.
Expanding Bookmarks
For any entry, if there is a + within the rectangle to the left,
there are sub entries which can be displayed upon expanding
the tree by clicking the rectangle. For example, clicking the
+ to the left of any chapter will expand it into major
headings and, by clicking all the + symbols, the complete
tree for that chapter will be shown. In the following figure
we can see the entry System 824 Virtual Instruments
completely expanded.
1-2
824 Reference Manual
2/6/17
Click to Display Page
Left click on any text field (Chapter name, Appendix name,
Table of Contents, Index, or any sub heading) and the page
displayed on the right will jump to the page associated with
that text field.
Return to Previous View
To return to the page which was displayed previous to
clicking on a bookmark text line, right click on the display
page, then left click on “Go to Previous View”.
Links
Click to Display Page
The Table of Contents and the Index have a page number
associated with each item. For the Table of Contents, left
click on the text line and that page will be displayed. For the
Index, left click on the page number itself to display the
page associated with that entry. To return to the previous
display, follow the procedure described in “Return to
2/6/17
Introduction
1-3
Previous View” on page 1-3
About This Chapter
This introductory chapter covers the following topics:
•
Formatting Conventions: Provides an explanation of
the fonts and other formatting conventions used in this
manual.
•
Features: Gives an overview of the System 824 keypad,
functions and measurement capabilities.
•
Getting Started: Provides instructions for unpacking,
inspecting and initially assembling the System 824.
Formatting
This manual uses the following format conventions:
In step-by-step directions, the process (what you do) is
shown in the right column, and the rationale (why you do it)
with other cautions and comments are shown in the left
column.
Keys to press on the LxT are shown with the icon
representing the appropriate key. For example:
Press the v key
Items that appear in various on-screen menus (such as
settings) are shown in bold and italicized style. For example:
Detector
1-4
[Slow]
824 Reference Manual
2/6/17
Features
Hardware Features
The Larson Davis System 824 has the following features:
•
Large backlit bitmapped graphic display
•
Soft rubber backlit keys
•
Pop-up menus with scroll bars
•
Pick and choose setup...just click and run!
•
File management system (stores multiple measurements)
•
Multiple Instruments
SSA: Sound Spectrum Analyzer combining a
sound level meter and real-time spectrum analyzer
(optional)
LOG: Logging SLM (optional)
ISM: Integrating SLM (standard)
RTA: Adds high speed spectral data gathering
(optional)
FFT: Adds Fast Fourier Analysis to the 824
(optional)
AUD: Gives the 824 the ability to certify
audiometers; used in conjunction with the AUDit
software (optional)
TAL: Measures tonality according to DIN 45681
and appraisal of low frequencies according to DIN
45680 (optional)
•
2/6/17
Type 1 precision integrating sound level meter: satisfies
IEC61672-1 (tested with 377B41 microphone only), IEC
60651-1993, IEC 60804-1993, and ANSI S1.4 1985)
Introduction
1-5
The windspeed (tacho) and wind
direction (throttle position) feature
requires the firmware option 824WND, not included with standard
System 824 configurations.
•
Simultaneous measurement of sound pressure level using
Fast, Slow, Impulse, Peak, and Leq detectors with A, C,
and Flat weighting (SSA, ISM, LOG, and TAL
instruments)
•
Exceptionally large dynamic range (> 93 dB for SSA and
> 115 dB for ISM and LOG)
•
Digital filters with real-time rate to 20 kHz satisfying
IEC 1260-1995 Class 1 and ANSI S1.11-1986 Type 1-D
meeting linearity specifications over a range of 85dB:
- 1/1 octave, 16 Hz to 16 kHz (11 filters)
- 1/3 octave, 12.5 Hz to 20 kHz (33 filters)
•
Automatic logging of sound level parameters including
Interval data, Ln statistics, noise event detection using
exceedance history and exceedance time history (LOG
only)
•
Measurement of windspeed (tacho) and wind direction
(throttle position) using external weather transducers
with inclusion of data in Views and Data Displays for
SSA and LOG instruments.
•
Real-time 1/3 octave spectrum analysis with rapid
spectrum vs. time autostorage and triggering for sound
decay measurement (RTA)
•
Simultaneous operation of sound level meter with
independent frequency and 1/3 octave analyzer function
weighting (SSA)
•
Advanced time history feature allows you to store up to
38 different parameters including spectral data with each
time history sample
•
Narrow band real-time frequency analysis with 400-line
FFT and Hanning, Flat-Top or Rectangular window (FFT
Mode)
•
Standard memory (2 MB) sufficient to store one of the
following:
- 30,000 point 1/3 octave SSA Leq time history
- 20,000 intervals with 1/3 octave Leq spectrum
1-6
824 Reference Manual
2/6/17
- 12,300 SSA intervals with Leq & Max 1/3
octave spectra
- 60,000 LOG intervals without Ln
- 35,000 LOG intervals with Ln
- 1,000,000 point time history
- 70,000 RTA 1/1 octave spectra
- 28,000 RTA 1/3 octave spectra
- 2400 FFT 400 line snapshots
2/6/17
•
AC/DC output, unweighted, with gain to 50 dB and
attenuation to -20 dB
•
Flash memory for in-field firmware upgrades
•
Multi-tasking
processor:
provides
simultaneous
measuring, viewing, transferring and printing of data
•
RS-422 (RS-232 compatible) interface:
Serial bit rate to 115 kbps
•
Direct report printouts
•
WindowsTM-based software included for setup, control,
and high speed data downloading and translation to
ASCII format
Introduction
1-7
System 824 Components
Condenser
Microphone
Preamplifier
38 cm
(15”)
LCD Display
Keypad
9 cm
(3.5”)
Connectors
Figure 1-1 The System 824 is a convenient hand-held sound
level meter with a simple user interface.
The standard System 824 shown in Figure 1-1 includes the
following:
1-8
•
1/2” diameter condenser microphone
•
Backlit graphic 64 x 128 pixel LCD display
•
14-key soft rubber backlit keypad
•
AC/DC output, control, serial, and external power
connectors (shown in figure Figure 1-2)
•
True “hand held” instrument with “sure grip” pads
824 Reference Manual
2/6/17
AC/DC Output Connector
Control Connector
Serial Interface Connector
External DC Power Connector
Figure 1-2 The System 824 has a series of connectors located at
the bottom of the device consisting of an AC and DC output
connector, control connector, serial interface connector, and
external DC power connector.
The following is a layout of the control connector, which is
used to control external devices and receive external wind
and control information:
Ground
Windspeed
Logic In
3
Cal Check
7
Logic Output
Wind Direction Input
1
2
4
5
8
6
Wind Direc Power
9
Ext Power
Heater Cntrl
Figure 1-3 9 pin mini DIN control connector; solder view
1 - Ground
2 - Logic output (0 to + 5 volts, active high, through 1 k)
3 - Logic input (0 to + 5 volts, active high, 100 kload)
4 - Wind speed input (.05 to 10 Vdc peak to peak, 10 k
load)
5 - Wind direction A:D input (0 to 2.5 Vdc, 100 kload))
6 - Wind direction power (+5 Vdc through 250 )
2/6/17
Introduction
1-9
7 - Calibration control output (0 to +5 volts, active high, 10
k)
8 - Heater control output (open drain, +40 Vdc Max, 100
mA Max)
9 - External power input/output (+8 to +15 Vdc)
The serial connector is used for computer, printer and
modem communications:
1
3
6
2
4
7
5
8
Figure 1-4 The serial connector is an 8 pin mini DIN connector
(AppleTalk TM compatible pinout).
1 - Flow control output (RS-232C levels)
2 - Flow control input (RS-232C levels)
3 - Transmit data negative output (RS-232C levels)
4 - Ground
5 - Receive data negative input (RS-422)
6 - Transmit data positive output (RS-422)
7 - Control input (RS-232C levels)
8 - Receive data positive input (RS-422)
Both outputs have a 600 ohm series
resistance.
1-10
The AC/DC output connector is used to output the signal
from the System 824 microphone to external devices such as
DAT recorders, real-time analyzers, other sound/vibration
measurement equipment, voltmeters, chart recorders, etc.
824 Reference Manual
2/6/17
NOTE: See the section “AC/DC Output”
on page 6-5 for more details concerning
the AC/DC outputs.
AC Output (Tip)
DC Output (+)(Ring)
Ground (-)
Figure 1-5 AC/DC output connector
Preamplifier Input Connector
The preamplifier input connector accepts the PRM902
preamp.
System Diagram
Figure 1-6, illustrates the acoustic-to-digital signal path in
the System 824. As you can see, incoming sound is first
converted to an electrical signal by the microphone. This
electrical signal is amplified, filtered and then sampled by an
analog-to-digital converter (ADC). The processor then
2/6/17
Introduction
1-11
calculates all of the desired data based on the sampled data
(sample rate of 48-51.2 kHz).
Getting Started
This section outlines the steps to unpack the System 824.
The following topics are covered:
•
Unpacking and Inspection
•
Accessories and Optional Equipment
•
Connecting Internal or External Power
•
Environmental Considerations
You will then be ready to use the System 824 for actual
measurements.
Unpacking and Inspection
Your System 824 has been shipped in protective packaging.
Please verify the package contains the items listed below.
Retain the packaging for safe shipment for calibration
service. Report any damage or shortage immediately to
Larson Davis, Inc. at (801) 375-0177.
If you have not already done so, please record the purchase
date, the model and serial numbers for your instrument, preamplifier and microphone in the spaces provided on the
copyright page near the beginning of this manual. You will
find the instrument’s Model/Serial numbers printed on the
label on the instrument’s back panel. The microphone’s
Model/Serial numbers are located on the inside ring of the
microphone. The pre-amplifier’s Model/Serial numbers are
engraved the outside surface. You may be asked to provide
this information during any future communications with
Larson Davis, Inc.
Comments concerning the
Digital Signal Processor
1-12
Although the System 824 does have analog Flat, A-weight,
C-weight and 10 Hz high pass filters ahead of the Analog to
Digital Converter, most of the measurements use digital
824 Reference Manual
2/6/17
Figure 1-6 System Diagram
Sysjklsfdakjl;fasdjl;kasdflj;ksdfal;jkklj;kl
Figdfdsafdsa
2/6/17
Introduction
1-13
Key Pad
Control I/O
Battery
Power
Supply
Preamplifier
Temperature
Sensor
External
Power
mic
RAM
1/2 to 2 MB
Analog to
Digital
Converter
0-50 dB gain
0-50 dB gain
Flash ROM
Real-time clock
and calendar
Microprocessor
Detection
Frequency
Flat, A-Wt, C-Wt
or 10 Hz High Pass
Flat, A-Wt, C-Wt
or 10 Hz High Pass
Serial I/O
Analog to
Digital
Converter
Mux
RS-422/232
transceiver
DC out
AC out
AC out
AC/DC out
Serial I/O
Graphic
Liquid Crystal
Display (LCD)
128x64 with
backlight
Digital
Signal
Processor
824 System diagram
weighting filters created by the Digital Signal Processor.
The Digital Signal Processor implements the following in
order to provide measured data for a wide range of
weightings, filters and detectors.
•
A, C and Flat broadband filters
•
Real-time FFT and 1/1 and 1/3 octave band filters
•
Slow, Fast and Leq true RMS detectors
•
Impulse and Peak detectors
Accessories and Optional Equipment
The System 824, 824S, 824L and 824A can be purchased
with or without a microphone; they all include the Model
PRM902 microphone preamplifier.
The System 824, 824L and 824A are delivered with the
following standard accessories (824-ACC Pack):
•
Battery pack, NiMH, 3.6 V, 1.2 AH (BAT010)
•
Reference Manual (I824.01)
•
Serial cable, DB9S to DIN08 (CBL006)
•
AC/DC output cable, 1/8" mini phone plug to dual phono
or BNC (CBL042)
•
Universal AC power adapter. (90 to 264 Vac, 50 to 60
Hz, 12 volt output) (PSA027)
•
Alkaline battery terminal assembly (AM814.06) Connects
individual alkaline batteries when NiMH battery pack is not
used.
1-14
•
Hard case 15”x19”x7” (CCS001) with foam insert
(0860.0077)
•
WindowsTM utility software (SWW-824-UTIL)
•
10 foot microphone extension cable (EXA010)
•
3 1/2” diameter windscreen (WS001)
824 Reference Manual
2/6/17
The 824S is delivered with the following standard
accessories (824S Pack):
•
3 x 1.5 V “AA” alkaline batteries
•
Alkaline battery terminal assembly (AM814.06) Connects
individual alkaline batteries when NiMH battery pack is not
used.
•
3 1/2” diameter windscreen (WS001)
The following optional equipment is also available:
2/6/17
•
CAL200 Sound Level Calibrator, 1000 Hz @ 94 or 114
dB (IEC 942-1988 Class 1)
•
CAL250 Sound Level Calibrator, 250 Hz @ 114 dB (IEC
942-1988 Class 1)
•
Microphone extension cables are available in 1.5, 6, 10,
20, 25, 35, 50, 66, 100, and 200 foot lengths or custom
lengths up to 328 feet.
•
Direct BNC microphone input adapter (ADP005)
•
External Battery Charger (PSA024) (Used to quick
charge the BAT010)
•
Accelerometer preamplifier for ICP accelerometers
•
426A12, Permanent Outdoor Preamplifier with
Electrostatic Actuator, humidity reading, TEDS and
supporting externally and pre-polarized microphones.
(MIC not included).
•
CBL824 to 426A12 Signal Cable, 20 ft.
•
CBL197, 824 to 426A12 Control Cable, 20 ft.
Introduction
1-15
If the System 824 is not being used
for long periods of time (1 month or
more), it is recommended that the
batteries be removed to avoid
damage to the instrument.
NOTE: Two Terminal assemblies are
provided though only one is used. The
second one is a spare. To avoid losing
them, keep them in the accessory kit in
the carrying case provided.
Connecting Internal or External Power
The 824 is shipped with a NiMH
battery pack installed.
The System 824 can be powered using a 3.6 V NiMH
battery pack, individual alkaline or NiMH cells, or an AC
power supply adapter. For specifications on operating time
under battery power, see “Battery Operating Time (full
capacity, continuous operation, reference environmental
conditions, individual cells may vary in performance)” on
page -C-5. Below we will discuss how to install and use
each.
Using the NiMH Battery Pack
To use a NiMH battery pack (BAT010) with the System 824,
unscrew the battery cover at the back of the System 824 by
hand or using a flat blade screwdriver. If individual cell
batteries were previously used, remove the Terminal
Assembly (Figure 1-8). Insert the battery pack so that the
positive terminal is oriented down and to the right, as shown
in Figure 1-7.
Positive
Terminal
1-16
824 Reference Manual
2/6/17
Figure 1-7 Battery compartment and cover with NiMH battery
pack installed. (Note location of positive terminal.)
Using Alkaline Batteries or
Individual NiMH rechargable
cells.
Use Duracell MN 1500 (1.5 volt,
2,850 mAH) alkaline battery or
equivalent. You may also use the
Duracell Ultra or Energizer
Titanium next generation batteries
which may provide up to 40% more
run time.
To use alkaline batteries or individual NiMH cells, remove
the battery cover, and if installed, remove depleted batteries
(or NiMH battery pack). If not already installed, insert a
battery Terminal Assembly (AM814.06) so that it is
positioned as shown in Figure 1-8. Insert three AA batteries
so that polarities match those indicated in the battery
compartment and secure the battery cover.
Note: It is important to set the
battery type to NiMH if individual
NiMH cells are being used to power
the instrument; otherwise there will
not be sufficient battery reserve to
preserve the memory once the
batteries are drained. Also, the
proper setting is important in terms
of the ability of the instrument to
accurately estimate the remaining
battery life
Indicate the battery type being used as follows;
Step 1
Press the v key.
Step 2
Press the c
Step 3
Use the dkey to highlight “Type”
Step 4
Press ckey to activate the “Battery Type” menu.
Step 5
Press dor ukeys to select the
appropriate battery type; alkaline or NiMH.
Step 6
Press the c key to enter the selection,
followed by the lkey to close the Power
menu.
key
If the rechargeable LD BAT010 battery pack is used, the
setting is overridden and assumed to be NiMH. The 824 will
automatically detect the presence of the pack, so the setting
can be left to what would most likely be used if individual
cells were to be used instead of the battery pack.
Note: The System 824’s “smart”
charging system is designed to detect
alkaline batteries and prevents
accidental charging.
2/6/17
If alkaline cells are installed but erroneously declared as
NiMH, the charger will start for several seconds, then will
detect that they are not NiMH. Charging will be terminated
and the battery type changed to alkaline. This safety
measure will prevent primary cells from being charged and
damaging the instrument due to leakage or explosion.
Nevertheless, it is inadvisable to ever attempt to charge
primary or non-rechargeable batteries.
Introduction
1-17
Rechargeable individual NiMH cells can also be charged in
an external rapid charger.
For additional battery information,
refer to the section vPower key on
page 3-3. For detailed information
on charging NiMH batteries, refer to
the section “Power Settings” on
page 3-5
If power is supplied with the AC
Power adapter, the NiMH or alkaline
batteries do not require removal and
will power the unit if the AC power
adapter fails. Without AC power or
batteries installed, memory loss will
occur.
Figure 1-8 Battery Terminal Assembly orientation.
Terminal
Assembly
Figure 1-9 Battery cover and compartment with alkaline
batteries and Terminal Assembly installed. (Note location of
Terminal Assembly.)
Using the AC Power Adapter
1-18
You may use an external power source via the external
power connector using the provided power adapter. The
System 824 accepts 6 to 15 VDC and is internally fused at
0.5 A.
824 Reference Manual
2/6/17
CHAPTER
2
Overview
This Chapter presents a general overview of the structure of
the Model 824, an example of selecting a Setup or Instrument Definition (ID), performing a measurement and storing
the data. Subsequent chapters will deal specifically with
these steps in a more structured manner.
System 824 Setups or Instrument Definitions
The power and flexibility of the System 824 gives you a
variety of measurement possibilities. The System 824 has a
number of distinct setups or Instrument Definitions (ID)
from which you can select the one best suited for a particular
application. You can, of course, modify any instrument
definition for another application and add it to the existing
list of instrument definitions.
The System 824 was designed to be
upgraded with new instrument
capabilities as they are made
available. Please contact Larson
Davis for information on the latest
available upgrades.
2/6/17
An ID name consists of an eight character name followed by
a three character extension called the Instrument Type. Some
IDs presently available are: SLM&RTA.SSA, SLM.ISM and
Logging.LOG.
The complete ID consists of its name and an instrument
setup based on one of the available Instrument Types. There
are a number of factory supplied setups available for use by
the user. In order to create a new setup, modify an existing
ID and store it under a different name as a new setup. The
Instrument Type will remain the same as that of the ID used
to create it. Thus, a new setup created for the measurement
of environmental noise by modifying the Logging.LOG ID
might become ENV.LOG.
Overview
2-1
Instrument Definition (ID) Types
Instrument Definition (ID)
SLM&RTA (SSA)
Logging (LOG)
SLM (ISM)
SLM Range (dBA)
80
105
105
Real-time Spectrum
Analysis
1/1 and 1/3 octave
bandwidths
No
No
Manual Data Storage
Yes
Yes
Yes
Back Erase
Yes
No
Yes
Automatic Data
Logging
Time History
Intervals (sound level
and spectral data)
Time History
Exceedance Events
Intervals (sound level)
No
Major Applications
Noise Reduction Sound
Power
Noise Monitoring Noise
Workplace
Point & Shoot
Law Enforcement
Workplace Noise
Write Protect, Delete, Write Enable IDs
After an ID has been created, it can be protected (or locked),
or deleted if necessary. This is described in detail in the
section "Write Protect, Delete, Write Enable IDs" on page 317.
SLM&RTA (SSA)
The SSA ID performs simultaneous sound level
measurements and real-time spectrum analysis using 1/1 or
1/3 octave bandwidths. The Instrument Type designation
“SSA” represents Sound Spectrum Analyzer. Sound levels
during the measurement period are displayed and can be
stored for later recall. In addition to a live spectrum display,
the System 824 can display an equivalent level (Leq)
spectrum, a minimum bin by bin level (Lmin) spectrum and a
maximum level (Lmax) spectrum, which is the spectrum time
2-2
824 Reference Manual
2/6/17
coincident with the maximum value of the sound pressure
level during the measurement period.
A back erase function allows the removal of up to the last 30
seconds (in one second steps) of data when a disruptive
noise occurs.
The 824 also provides an automatic measurement and
logging feature which provides the sound level parameters
Leq, SEL, Lmax, Lmin, LPeakand the Leq and Max or Min
spectra data at regular user-defined time intervals. Due to the
complex digital processing necessary to perform
simultaneous sound level measurements and spectrum
analysis, the measurement range in this mode is reduced to
80 dBA.
The design of the System 824 permits the simultaneous
measurement of the following sound level parameters, a
feature we call “Any Data”:
Leq
Peak
Live SPL
Lmax
Lmin
Detectors
Detectors
Detectors
Slow
Fast
Impl
Slow
Fast
Impl
Slow
Fast
Impl
A











C











Flat











Note: The detector used to create
Leq is a pure integrating true RMS
detector which integrates the energy
over a specific period of time. It may
be as short as 1/32 second, in a time
history which may be as long as 24
hours. As a result, it does not include
decay artifacts of older instruments
that integrate the output of the
SLOW or FAST detectors.
2/6/17
Peak Sound Pressure Level (Lpeak) with A, C and Flat
weighting.
Equivalent Continuous Sound Pressure Level (Leq) with
A, C and Flat weighting. A time history record can be
enabled to capture samples at periods as short as 1/8th of a
second.
Spectral Analysis with Time History Record allows you to
record spectral data along with the 33 sound level
parameters mentioned above.
Overview
2-3
An interval history which includes 6 Ln values (6 values
with 0.1 dB resolution, based on user-selected percentages
with 0.01% resolution).
For Takt users, as a no-cost option, the following additional
parameters are provided:
with the following combinations of frequency
weighting and time weighting:
Taktmaximal
Taktmaximal 3
Taktmaximal 5
Slow
Fast
Slow
Fast
A




C




Flat




SLM (ISM)
The SLM (ISM) is the simplest to operate, providing the
functions of a “point-and-shoot” sound level meter with
manual data storage. The SLM (ISM) Instrument ID
measures the same thirty-three sound level parameters as the
SLM&RTA (SSA) ID, but it does not provide frequency
spectrum measurement capability. However, since less
digital processing is required, the measurement linearity
range is 105 dBA, permitting the use of a single range for all
measurements.
Logging (LOG)
This ID is designed particularly for noise monitoring
applications and provides extensive automatic data storage
features. The Instrument Type designation, LOG, represents
a Logging sound level meter. Like the SLM (ISM) ID, the
measurement range is 105 dBA and does not provide
frequency spectrum measurement capability. Up to thirty-six
measured sound level parameters can be stored as a Time
History record at rates as rapid as 32 samples per second.
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The following parameters can be logged at user-selectable
time intervals between 1 second and 99 hours (hh:mm:ss)
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•
Lmax, Lmin, SEL, and Leq (q=3) or Time Weighted Average (q=4, 5, or 6) levels for a selected detector (Slow,
Fast, or Impulse) and a selected frequency weighting (A,
C, or Flat)
•
Lpeak level corresponding to the frequency weighting
selected for Leq (see charts above) and a second Lpeak
level corresponding to one of the two alternative choices
of frequency weighting.
•
Ln (6 values with 0.1 dB resolution, based on userselected percentages with 0.01% resolution)
•
Date, time and duration of interval
•
Six user-selected values of Ln can be measured and
stored as part of the automatic interval data storage function.
•
A special feature is the automatic measurement and logging of data associated with noise exceedance events that
are triggered by the sound level exceeding a user-defined
threshold. Leq, SEL and LPeakfor each event are logged
along with a Time History of the sound level during each
event.
•
Daily history and community noise metrics.
Overview
2-5
Selecting a Measurement Setup
The simplest way to setup the instrument is to select the ID
which most closely meets the requirements of the
measurement to be made and then modify it to meet your
specific needs. The instrument is delivered with a number of
permanent setups. The standard ID delivered with the
instrument is ISM. The optional IDs available are: SSA,
LOG, RTA, FFT, AUD, and TAL. If the options for the SSA,
LOG, RTA, FFT, AUD, or TAL have not been purchased,
they can be evaluated in a demo mode.
Restrictions of demo IDs:
•
Cannot print reports
•
Cannot store data
•
Cannot perform any I/O commands
•
Only 20 demos are permitted
•
Memory must be purged prior to activating these IDs
The following is an overview of how to select a
measurement setup.
Note that each of the permanent
setups has a letter “p” to the left of
the setup name, indicating that it
cannot be modified or deleted. It can
be saved under another name and
then modified.
Step 1
To display the available instrument setups, press
the S Setup key.
At any time, one of the available setups will be the
active setup. The name of this setup will be at the
top of the list below the Edit Setting message.
Pressing the c key while the “Edit Settings”
menu item is highlighted initiates the modification
procedure.
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After selecting a measurement setup,
press the s key to initiate the
measurement.
Step 2
To select the desired setup, scroll through the
setup list with the u and d keys until the
item is highlighted, then press c.
It will be shown later how the Setup Menu can be utilized to
modify one of the permanent setups to meet your
requirements. The 824 Utility software is also very useful
for selecting and modifying setups.
Performing a Measurement; SLM&RTA (SSA)
Without getting into the fine details of operating the System
824, let’s just press some keys and see what it can measure
and display.
You can see from the top line that the
meter is in the SLM+RTA mode, and
the bold SLM indicates that it is the
SLM display or VIEW as we refer to
it when using the Model 824.
2/6/17
Step 1
Let’s look at the SLM&RTA (SSA) ID Access the
Setup Menu by pressing S and use the dand
u keys to highlight the SLM&RTA ID, as
shown below:
Step 1
With SLM&RTA highlighted, press c to select it
as the current ID.
Step 2
Press the RUN/STOP key s to begin a measurement and obtain a display resembling the following:
Overview
2-7
The large numerals represent the SPL measurement taken
with the Slow detector and the A-weighting. In the lower left
is an indication of the Leq value and the elapsed time of the
measurement for which the Leq value is calculated. The
graph being traced across the display is a time history of the
SPL value.
Stop, Pause and Back Erase Functions
While taking a measurement you can stop, pause, and back
erase.
s key. Restart by
Stopping and Starting
Measurements
To stop the measurement, press the
pressing s.
Pausing Measurements
To pause the measurement press the p PAUSE key. To
continue the measurement press the p key a second time.
While paused, thelandrkeys can be used to move a
cursor across the time history and display the SPL and
secondary parameters as measured at any particular time
during the measurement period.
Back Erasing
Should an unwanted sound occur during the measurement,
such as a door slam, you can pause the instrument, cursor to
the left with thelkey to a time prior to the unwanted
event, and press the p key once more to recommence the
measurement from that point, erasing the data to the right of
the cursor. This is the Back Erase feature as indicated on the
display when the p key had been initially pressed.
Changing the detector of the displayed SPL value
You can change the parameters being displayed in the View
window while a measurement is in progress without going to
the Setup menu.
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Step 1
Step 2
To change to the detector type, use theuor d
keys to highlight the Slow detector, as shown
below:
To scroll through the optional detectors, press the
rorlarrow keys. This will display the SPL
corresponding to the Fast and Impulse detectors.
Go back to the Slow detector and press the check
c key or wait several seconds until the highlight
disappears.
Changing the frequency weighting of the displayed SPL value
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Step 1
To select the frequency weighting parameter, press
theuord keys to highlight the A-weighting
as shown:
Step 2
Use therorlarrow keys to display the Cweighted or Flat-weighted SPL corresponding to
the Slow detector.
Overview
2-9
Changing the displayed secondary parameter
Step 1
To select the secondary parameter to be displayed
(Leq in this example), use theuordkeys to
highlight the Leq label.
Step 2
Press therorlarrow keys to display the values of A-weighted SEL, Lmin, Lmax, Lpeak values. Select “Peak” and press the check c key.
Changing the frequency weighting of the displayed Lpeak value
Step 1
With the Peak label selected, press the uor
dkeys to highlight the Peak weighting.
Use therorlarrow keys to display the A, C or Flat
weighted Lpeak values.
Changing the amplitude range, or input Gain
When using the SSA ID, as in this example, the
measurement range is 80 dB, unlike the ISM and LOG IDs
for which it is 105 dB. In order to optimize a particular
measurement, provisions have been made to select a value
of input gain directly from the graphic display. The gain can
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824 Reference Manual
2/6/17
also be changed from the Setup Menu, as described later in
this manual or it can be changed here.
Step 1
To change the gain, Use theuordkeys to
highlight the Gain, as shown below
.
The gain shifts the dynamic range up
or down. See page 5-3.
Step 2
Use therorlarrow keys to change the input
gain.
Views
For each instrument type (e.g. ISM, LOG or SSA), a unique
set of data displays or VIEWS are available.
Selecting a VIEW
There are eight different VIEW choices available in the SSA
instrument.
Step 1
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To display the set of available data presentations,
or VIEWS, press the V View key (use thed
and u keys to scroll through the entire range of
choices).
Overview
2-11
The VIEW choices for the SSA instrument type are as
follows:
Use the upuand downdarrows
to select a menu item, rightrarrow
to enter a submenu and leftlarrow
to exit a menu.
2-12
SLM
Sound Level Meter parameters, graphic and
digital display
Any Data
Tabular presentation of sound level meter
parameters
RTA Live
Live display of real-time frequency spectrum
RTA Leq
Display of Leq spectrum over elapsed measurement period
RTA Max
Display of the live spectrum corresponding
to the maximum value of sound pressure
level occurring during the measurement
period.
RTA Min
The minimum level recorded for each frequency during the measurement.
Intervals
Sound Level parameters measured and automatically stored at regular user-defined time
intervals.
Leq Spectrum
Leq spectra measured and automatically
stored at the interval rate.
Max/Min
Spectra
Instantaneous spectrum corresponding to the
maximum sound pressure level occurring
during each of the user-defined time intervals or the minimum level for each frequency as selected by the “Intv Spectrum”
setting.
Time History
Sound Level parameters and spectral data
measured and automatically stored at user
defined time periods.
Run Log
Displays the start and stop times/dates of the
active measurement.
Ln Centiles
L1 - L99 displayed for the measurement
period.
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As part of this exercise, select each of these various VIEWs
and use thedandukeys to see how a variety of
different parameters are displayed within each function.
We have sought only to explain the general concept of the
VIEW function at this time. More detailed explanations are
provided later in Chapters 3 and 6.
Data Storage and Recall
When a measurement has been performed and the
instrument stopped, the measured data can be stored to nonvolatile memory before the instrument is reset or the setup
changed; otherwise the data will be lost. Attempting to
change the setup while there is measured data available will
cause the system to prompt you to store the data before
continuing.
Storing Data
Step 1
To store measurement data, press the D DATA
key. The following menu appears:
Step 2
With the message “Store File” highlighted, press
the c Check key to store the data.
Step 1
To recall stored data, highlight “Recall Files” and
press the c Check key. The following screen
appears.
The “Recall Files” line only appears
if data has previously been stored.
Recalling Data
2/6/17
Overview
2-13
Step 2
Press the up uand down darrow keys until
the desired file is indicated. Press the check c
key, select “Recall” from the menu and press the
check c key again.
Calibration
Power off the instrument prior to
connecting a microphone or
preamplifier; the high voltage spike
created when connecting while the
instrument is on can damage
sensitive electronic components.
2-14
Calibration is one of the functions available from the Tools
Menu.
Step 1
Press the T TOOLS key.
Step 2
Press thedkey to highlight “Calibration”.
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Step 3
Step 4
NOTE: The output level specified by the
calibrator manufacturer will be at
standard temperature and pressure. In
practice the level is a function of
temperature and static (barometric)
pressure, so a corrected level should be
used. Similarly, the sensitivity of the
microphone itself is a function of
temperature and static pressure. For
directions
on
compensating
for
temperature and static pressure during
calibration,
see
C
" orrection
of
Calibrator Output Level"on page 2-17.
2/6/17
To setup the calibration process, press therkey
to move into the Calibration Menu.
To set the calibration level, press the d and
u keys to highlight “Cal Level”,
Step 5
To set the value of the sound level provided by the
calibrator, press therkey. This displays the Cal
Level window.
Step 6
Then use thelandrkeys (to move the cursor
position) and theuanddkeys (to change digits) to enter the proper level.
Step 7
To select the new calibration level press the c
Check key.
Overview
2-15
Step 8
To verify that the instrument is properly calibrated, use theukey to highlight “Check”.
Step 9
Place the calibrator over the microphone, switch
the calibrator ON, and press c to activate the calibration Check process.
The display will show the measured level and the difference
from the calibrator level entered and the measured level as
shown.
Step 10 If the calibration is not reasonably close to the
level of the calibrator, the calibration can be
changed by choosing Change. Press c, use
thedkey to highlight “Change”.
Step 11 Switch the calibrator ON, and press c.
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Correction of Calibrator Output Level
The CAL200 provides a nominal pressure level of 94 dB or
114 dB. The exact levels are printed on the Larson Davis
calibration sheet that is delivered with the calibrator. The
free field level is -0.12 dB from either of these levels. If the
calibrator and instrument are near room temperature and
near sea level then no other corrections need to be made. If
the calibration sheet for the CAL200 indicates 113.98 dB for
it's level when set to 114 dB then set the Cal Level in the 824
to 113.86 dB.
When the microphone and instrument are at a temperature
other than near room temperature or static pressures not near
sea level, then corrections need to be added for the ambient
temperature and the prevailing static pressure. Check the
calibration data shipped from Larson Davis with the
CAL200 to get these corrections. The corrections can be
added to the level obtained in the previous paragraph to get
the actual level of the CAL200.
The 377B41 microphone's sensitivity varies with static
pressure. The coefficient of static pressure is -0.01 dB/kPa.
If the system is calibrated at 85 kPa for instance then it will
be 0.16 dB less sensitive at sea level. The 377B41 and 824
vary with temperature. The coefficient of temperature is
+0.012 dB/°C. If the system is calibrated at 25°C then it will
be 0.024 dB less sensitive at 23°C.
2/6/17
Overview
2-17
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CHAPTER
3
Front Panel Keys; Functions
and Menus
This chapter contains an overview of the functions which are
accessed through the System 824 keypad (see Figure 3-1
below):
Figure 3-1 System 824 Keypad.
The 14 keys on the System 824 keypad are organized into
these four sections: Power, Measurement, Navigation, and
Control. These keys are covered in the following order in
this chapter:
Power Key
v
POWER
2/6/17
Turns on / off the System 824; accesses battery power monitoring and LCD utilities,
and is used to close menus.
Front Panel Keys; Functions and Menus
3-1
Measurement Keys
Begins and ends measurements.
s
RUN/STOP
p
PAUSE
R
RESET
Pauses readings while running, Previews
current SPL when stopped. Activates
Back Erase function.
Displays Reset options menu. (Current,
Overall, Options)
Navigation Keys
.... u
l
.....d
ARROW
c
SELECT
r
Used to move through System 824
menus, change settings, and scroll
through data displays. The lkey exits
menu’s.
Selects highlighted menu items (like a
button on a mouse), concludes data entry
(like the Enter key on a PC keyboard)
and activates context specific menus
(called Check menus).
Control Keys
V
VIEW
D
DATA
S
SETUP
3-2
Displays View menu choices where you
can select which data to view.
Displays the Data Files menu. This
menu is used to store and recall Data
Files.
Displays the Setup menu. Allows you to
view and edit the settings for the active
instrument or recall a stored Instrument
Definition (ID).
824 Reference Manual
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T
TOOLS
P
PRINT
NOTE: The reference information in this
chapter is organized according to functions, rather than by tasks (which can
use several functions).
Displays the Tools menu. Allows you to
change Calibration, Clock/Timer, Memory, Lock, Power Monitor, and Communication settings.
Displays the Print menu. Allows you to
change print settings, and to print data
reports and Snapshots.
The functions and displays associated with the above keys
are described next. In addition, relevant reference material is
included for settings and options which may be available for
keys on the System 824 keypad.
v Power Key
The purpose of the POWER key v on the System 824 is to
turn the power on or off, close menus, and display the
remaining battery life. Once the System 824 is turned on,
pressing the v key again will activate a PWR display
where you can change screen contrast, turn the backlight on
or off, and adjust power options. To turn the instrument off,
press and hold down the v key until prompted to Please
release key. Release the v key and the instrument turns
off.
This section discusses the following:
•
Power-up the Instrument / Viewing PWR Display
•
Power Settings
•
Extra Notes on Power Conservation
Power-up the Instrument / Viewing PWR Display
To turn on the power:
Step 1
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Press the v key.
Front Panel Keys; Functions and Menus
3-3
Step 2
Allow the instrument to stabilize as indicated by
the hourglass symbol in the screen’s upper right
hand corner.
Step 3
As soon as the hour glass icon disappears, the System 824 is ready to acquire data.
As soon as the System 824 is turned on, you can view the
battery life and display settings through the PWR display. To
do this:
Step 1
Press the v key so that the following PWR display appears:
Pressing thelor v key again
will return you to the previous
display.
From this display, you can adjust the
contrast and turn the backlight on or
off. Pressing the u or d key
adjusts the contrast. Pressing
ther key turns the backlight on or
off.
Note: If after powering up the 824
the display is not visible, turn the
unit off by holding down the power
key. Turn on the power again by
pressing the power key and holding
it down until you hear three beeps in
quick succession.
3-4
This simple display indicates that the System 824
is plugged into an external source which is 13.5
volts; the battery is 97% full; the backlight is off;
and contrast is at 62%.
Step 2
From the PWR display, you can adjust the Power
settings. To do this, press the c key. The following Power menu appears:
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Check menus allow you easy access
to system or instrument settings.
The uord arrow keys, allow
you to select the desired menu item
and by pressing the r key you can
make changes to the setting.
The settings menu allows you to adjust the contrast (or viewing angle), turn the backlight on or off, and adjust settings
that control the power-conservation features. These powerconservation features allow you to set the instrument to do
the following:
•
Turn the backlight off after a set amount of time
•
Automatically go into a standby mode after a set amount
of time (display blanks and serial port turns off)
•
Automatically shut off the instrument after a set amount
of time
•
Conserve internal battery for memory retention
If no keyboard activity is detected for the period of time set
by the Backlight Time setting, the instrument will turn off
the backlight. This conserves battery life since the backlight
is a major consumer of battery power. If Backlight Time is
set to zero (0), then the timer is disabled and the backlight
will stay on until turned off manually. If the battery capacity
is less than 30%, the backlight will automatically shut off in
3 seconds to conserve power. If the battery capacity is less
than 15%, the backlight will not turn on at all.
Power Settings
Use the u and d keys to move
from one setting to the next. Then use
the r key to change the selected
setting. The l key is used to
return to previous menus.
2/6/17
The Power menu provides the following menu items:
Front Panel Keys; Functions and Menus
3-5
Menu Items
Description
Status
Displays the Power Monitor display that shows the
current battery type and charger status.
Settings
Described later in greater detail.
Charge
Activates the smart battery charger.
Type
Select Alkaline or NiMH for individual cells. See
Connecting Internal or External Power” on page 1-16
Once the smart charger has been activated the 824 will not
allow you to shut it off when the power key is held down.
The 824 will beep and give the warning “Charging Battery,
Please Wait”. Simply press the power key again to force the
824 to shut off.
The charge mode will be activated
automatically when external power
is applied and the battery is at 75%
capacity or less.
WARNING!
3-6
Whenever external power is applied, the 824 will trickle
charge to keep the battery pack at full charge
The 824 must have external power applied and
be left “ON” in order for the battery pack to
charge!
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The power Settings menu item provides the following eight
settings:
Menu Items
Available Setting
Options
Description
Power Off Mode
Blank LCD
Auto Off
Manual Off
Blank LCD - The instrument LCD display and serial
communication port, will turn off after the keyboard
and serial port have been inactive for the period of
time set by the Standby Time setting.
Auto Off - If the instrument is stopped with no reports
printing, and the instrument remains inactive (i.e
with no serial interface commands or key presses),
for the period of time, set by the Auto-Off Time setting, the instrument will turn off.
Manual Off -
No automatic power reduction features
are enabled.
Auto Off Time
0 - 99 minutes
When Auto Off is activated, the System 824 powers
down in the specified number of minutes of inactivity.
Standby Time
0 - 99 minutes
Time (in minutes) when Standby Time power save is
activated. When activated, the System 824 screen
blanks and the serial port turns off. If any key is
pressed or if incoming serial activity is detected, the
instrument will exit Standby Time and become
active again.
Backlight Time
0 - 99 seconds
Time (in seconds) when the backlight is turned off.
The backlight is reactivated when any key is
pressed.
Backlight
On/Off
Turns backlight on/off.
LCD Contrast
0 - 99%
(The default contrast
setting is 66%)
Adjusts the contrast or viewing angle of the LCD
display. This is done by pressing either the up or
down arrow key. The u key increases the contrast
percentage, darkens the display and makes it visible
from a higher angle (when viewing from the bottom
of the instrument). The d key decreases the contrast percentage, lightens the display and makes it
more visible from a lower angle.
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Front Panel Keys; Functions and Menus
3-7
External Power
- Indicates that the external power source is
not a battery. If the external voltage is less than the
internal battery voltage, then the internal batteries
will supply power for the instrument.
AC Pwr
AC Pwr
Battery
Battery - Indicates that the external power source is a
battery (which should not be allowed to deep-discharge).
Min Battery
0 to 15.9 (10.8 volts
is the default setting)
Sets the external cutoff voltage when a battery is
used for external power. 10.8 volts DC is the recommended setting for a 12 volt battery.
Extra Notes on Power Conservation
NOTE: To exit the Power display, press
the left larrow key or use the view
key to the select desired view.
If you are using an external power supply, the v key will
display the constant voltage coming from the power supply.
If the external battery supply ever drops below 10.8 Volts,
set by the Min Battery setting, the 824 will automatically
turn off. Discharging some types of batteries (such as lead
acid) deeply will greatly shorten their service life.
For detailed information on the use of external power, see
“Power/Current Draw of 824 Using External Power” on
page C-49
WARNING!
Battery life is reduced by approximately 25% with the backlight on.
WARNING!
Loss of power may cause loss of memory
WARNING!
Turn off power to change the microphone or preamplifier.
Sensitive electronics can be damaged by voltage spikes.
s Run/Stop Key
Use the s RUN/STOP key to toggle the data gathering
mode of the instrument from stop to run, or from run to stop.
The mode of the instrument is indicated on the display in the
upper right hand corner by a running man symbol if the
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instrument is running, or a box symbol if the instrument is
stopped.
NOTE: The Indicator Box in the upper
right hand corner of the display will be
solid if data is present, or open if no data
has been taken.
Repeatedly pressing the s RUN/STOP key after beginning
a measurement will stop, then restart the measurement without resetting the data buffer. As a result, the time will continue to increase for the overall measurement.
R Reset Key
The R RESET key allows you to clear the data of the current measurement.
If you are using the simple sound level meter (SLM) instrument and wish to reset the data, simply press the R RESET
key. This will reset all the data including the accumulated
measurement values such as Leq.
The SSA, ISM, and LOG instruments
within the System 824, contain two
independent data buffers that can
separately accumulate data. In
essence, the instrument becomes two
sound level meters in one. The data
in the primary buffer is referred to as
the “overall” measurement, while
data in the secondary buffer is
referred to as the “current”
measurement.
For the other instrument types, the System 824 gives additional flexibility when resetting the data. If you press the R
RESET key while the instrument is running, the instrument will reset its data buffer for the current measurement
and set the elapsed time for the current measurement to zero
without affecting the data in the overall measurement.
If you press the R RESET key while the instrument is
stopped, a menu will appear that will give you the choice of
resetting the current data or the overall data together with the
appropriate elapsed time counters.
When editing system or instrument settings containing a
string of numbers or characters, the R RESET key can also
be used to clear the characters from the current position of
the cursor to the end of the string.
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Front Panel Keys; Functions and Menus
3-9
p Pause Key
The p PAUSE key has 3 basic functions in the ISM and
SSA instruments: To Pause a measurement to avoid
unwanted noise from entering into the measurement data. To
erase unwanted data from the measurement and to preview
the data coming into the instrument without registering the
data.
Pause
The first function of the Pause key will cause the instrument
to not accept any incoming data. Unlike pressing the stop
key, pressing the pause key will not start a new measurement, but rather will simply pause the existing measurement
for a moment. After the desired pause period, press the
pause key p again to resume the measurement. The following screen will appear.
Pause, Back Erase
The second function of the pause key is to remove unwanted
data from the measurement. The cursor is used for this function. Thelandrarrow keys move the cursor across the
graph.
NOTE: Moving the cursor bar left is like
moving back in time.
Once it is at the desired point, press the c key to delete the
data to the right of the vertical bar. After the instrument has
deleted the unwanted data, the measurement will resume
automatically.
Preview
Pressing the p PAUSE key when an instrument is
“stopped” brings up a Preview display which allows you to
view the SPL without affecting measured data. Pressing the
p PAUSE key again will exit this screen or simply press
the s RUN/STOP key to exit this screen and start taking a
measurement.
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lrud Arrow Keys
The u and d (Up and Down) arrow keys navigate
from one item to another in a menu, or from one record to
another when displaying history data. Pressing and holding
an arrow key will repeat the actuation of the key. These keys
are also used to modify settings. Use the u key to step to
the next higher number or character value, and use the d
key to step to the next lower number or character value.
Pressing and holding an arrow key
will repeat the actuation of the key.
The repeat rate increases as the key
is pressed for a longer period of
time. Key pressure also has an effect
on the repeat rate as does the
amount of data available to view.
Thelandr(Left and Right) arrow keys move between
data displays, to move between characters of a setting being
modified and to move through menus. Use ther arrow
key to move from the current menu into a sub-menu or to
modify a setting. Use thelarrow key to move out of a setting, to move from a sub-menu back to its parent menu, or to
move back to a previous menu or display. The l and r
(Left and Right) arrow keys will also move the vertical cursor bar within certain measurement displays.
c Check Key
The c key allows you to choose an item from a menu or to
confirm the entry of a setting.
Pressing c in many displays will bring up a menu from
which you can make changes to settings appropriate to that
display.
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V View Key
The display of data on screen of the System 824 is controlled
by the V VIEW key. Each instrument type (e.g. SSA, ISM,
or LOG) has its own set of available data displays which are
selected using this key. When you press the V key, a menu
containing the available data displays will appear. The following example is a View menu for the SSA instrument:
Theuordkeys and c key allow you to select the
desired display. While viewing data, often more than one
display screen is available. You can use the l and r
arrow keys to move from one screen to another.
The data displays available under the V key depend on the
instrument type used to measure the data. These will be
described in more detail in later chapters dedicated specifically to each instrument type.
D Data Key
The D DATA key controls the storing and recalling of
measurements, or data files from memory. Each file may
contain cumulative data, time history, interval history, calibration data and histogram tables that can be stored as distinct measurements from other measurements with their data
and histories. A list of all stored measurement data is shown
and individually recalled by selecting it using the arrow keys
and check key.
To access the Data Files menu press the
screen similar to the following appears:
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D DATA key. A
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If no data files have been saved, the
Recall option will not be available
for recall.
From this menu you can store data or view and recall stored
data.
If the instrument is running when
you try to store a Data File, you will
be
prompted
to
stop
the
measurement before storing the file.
To store measurement information into a Data File, highlight Store File using the u or d keys. Press the c
key to select. The instrument will beep once to signify that
the measurement has been stored.
To view a data file, use the uor
d keys to select the desired data
file. Each data file is marked with a
number and the instrument used
(e.g.: SLM&RTA SSA).
Press the D Data key again and select Recall Files to view
a summary of the stored data files. The following screen
appears:
To move from one record to another,
use theuordkeys.
The Data Files screen shows the currently selected record
number (1/4), start & stop dates and times, and the total
bytes used by the record.
To exit the Data Files view, press the
lto return to the previous display
or select a new view using the V
VIEW key.
Pressing the c key from the Data
Files display, brings up a menu that
allows you to recall data, jump to
beginning or end of all records, find
a specific data file, or purge all data
files.
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Pressing the c key and selecting Recall File from the Data
Files menu, allows you to recall that measurement. An
active data display will be shown.
When recalling a data file, the System 824 will switch to the
instrument definitions (ID) that the data file was stored as
(i.e. SLM&RTA to Logging, if the user was currently using
the SLM&RTA instrument and recalled a Logging data file).
If the run key s is pressed while a recalled data file is
active, the data is reset and the new data is taken using all of
the settings that were stored with that data file.
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3-13
The data file also contains calibration information that may
be different than the current calibration. When Run is
pressed, the recalled calibration is replaced by the latest /current calibration.
S
Setup Key
To the left of each ID is a symbol
giving information about that ID:
The ‘>’ symbol indicates that the ID
is currently active or that the ID is
currently in memory. The lock
symbol indicates that the ID is
locked which protects the ID from
being easily deleted. Press TOOLS
to write protect or un-protect an ID.
The ‘p’ symbol indicates that the ID
is permanent and pre-defined.
The’ ’ symbol indicates that the ID
has changed and has not yet been
saved.
Use the S SETUP key to access the Setup menu where you
can select, create, and manipulate groups of instrument settings known as “instrument definitions” (ID). The Setup
menu presents a list of pre-defined IDs (marked with a “p”)
and user-defined IDs (if previously configured) that are
available for use. To access the Setup menu, press the S
key. A screen similar to this appears:
*
An ID defines the data that is to be measured for a particular
project or type of application. The defined project IDs are
listed in the Setup menu. You can create, edit, copy, and
delete these project settings within this menu. You can also
define a project ID on a computer using the 824 Utility software and then install it into the instrument where it may be
selected for use. For example, one project may require the
“simple SLM” where no data logging is performed and the
weighting and detector controls are available in the data display (rather than in a menu). Another example may be an
hourly statistical measurement set to run for 8 hours using a
LOG ID.
If data from a previous ID was not
saved, you will be prompted to do so
at this time. If settings to the current
ID have been made, you will be
prompted to save the ID at this time.
The ISM and AUD instruments do
not issue these prompts.
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To select an instrument definition (ID), use the u or d
keys to highlight the desired ID. Press the c key to select
and activate the it. The Setup menu then closes and the main
display appears.
The modification of a selected ID to meet the requirements
of a particular measurement application is an entire topic in
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itself which will be addressed in general in the next chapter
and in detail in later chapters individually describing the
setup and operation of each of the instrument types available
for the System 824. However, once these modifications have
been made, the new ID is named and stored as described in
the following section.
Use the Setup Tools menu to create new IDs. To do this,
press the S SETUP Key and highlight the Edit Settings
menu option. Press the T TOOLS key to display the following screen:
With the Setup Tools menu you can create and/or modify
instrument definition (ID) settings. The Setup Tools menu
provides the following three options, which are later
described in greater detail.
:
Menu Items
Description
Save ID
Saves/Creates an ID
Title
Description of ID
ID Name
Name of ID
Save ID
The Save ID menu item saves or creates an ID. Use the u
or d keys to highlight Save ID, then press c. You will
then be prompted to verify the name for the ID. (See ID
Name below)
Title
You can attach a description to your ID with the Title menu
item. This description can be used on printed reports and
other items. The Title field is capable of holding up to 30
characters.
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ID Name
You use the ID Name menu item to give an ID a unique
name that represents the ID in the Setup menu. The ID
Name field is capable of holding up to 8 characters.
Name format: “cccccccc.ccc” The first 8 characters form the
name and the last three are the extension that indicate the
instrument type (e.g. “SSA”). The name does not have to be
a full 8 characters long. Leading spaces and symbols will be
removed from a name. Case is preserved but ignored when
finding names. Embedded spaces will be converted to underscore. The name should start with a letter or number. The
characters generally used in a name are A to Z, 0 to 9, and _
- (underscore, and dash) but may also be “ ‘ ( ) [ ] !@ # % $
^ &.
The allowed characters in names for IDs are compatible with
PC filenames. The following characters are NOT allowed:
*+,./:;<=>?[\]|
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Write Protect, Delete, Write Enable IDs
NOTE: Within a given active instrument
definition (ID), write protect or delete
operations cannot be performed on files
that were stored using that same ID. In
order to protect or delete these files, the
active ID must be changed. For example,
stored FFT files can be protected or
deleted by switching from the FFT ID to
an ISM, LOG, or RTA ID.
After an ID has been created, it can be protected (or locked),
or deleted if necessary. To do this, use the u or d keys
from the Setup menu to highlight the desired ID.
Press the T TOOLS key, and the following screen appears:
The ID that is active, with a “>” by
it, cannot be deleted
Permanent IDs (marked with a ‘p’ in
the Setup menu) cannot be write
protected, modified, or deleted.
Write protected IDs (marked with a
locked symbol on the Setup menu)
cannot be deleted. The icon will not
be displayed if the currently active
ID is being used. Also, the currently
active ID cannot be deleted.
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To write protect (or lock) an ID, use the u or dkeys to
highlight Write Protect, and then press the c key. A locked
symbol appears next to locked IDs in the Setup menu
(except for the current running ID) and symbolizes that this
ID is “Write Protected”. Once the ID is write protected, it
cannot be changed or deleted until it is “Write Enabled”.
To delete an ID that has not been write protected, use the
u or d keys to highlight Delete ID, then press the c
key. The ID is removed from memory and the ID name is
removed from the Setup menu.
To write enable (or unlock) an ID, use the u or d keys
from the Setup menu to highlight the desired write protected
ID (marked with a locked symbol). Press the T TOOLS
key. Press the c key on the highlighted Write Enable menu
option. The locked symbol disappears next to the ID shown
in the Setup menu, symbolizing that this ID is write enabled.
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3-17
TTools Key
NOTE: In certain situations you also use
the T TOOLS key to delete, write
enable, or write protect instrument definitions (ID) from the Setup menu (as
previously described).
The T TOOLS key allows you to access controls and operations such as calibration, battery usage, memory usage, setting date and time, timer, or computer port settings. You
press the T TOOLS key to access the Tools menu. To modify settings press the r key on a menu item from the
Tools menu. Pressing the c key on a menu item from the
Tools menu allows you to view system settings and other
displays.
NOTE: From any of the following displays, the u and d arrow keys will
step to the next or previous display in the
list.
The Tools menu provides the following seven options,
which are afterwards described in greater detail:
Menu Item
Available Settings Options
(rkey from Tools menu)
Setting Screens
( c key from Tools menu)
About
Name (company name)
Name (address line 1)
Name (address line 2)
Title (30 characters)
Date Format (Normal or ISO8601)
Takt (enables Takt functionality) Yes or No
a - System revision information
b - User information
c - Installed instrument options
Calibration
Check
Change
Cal Level
Calibrator S/N
Noise Floor (not all versions)
Calibration - dates, times, and measurement when checked or changed
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Clock/Timer
Current Time
Current Date
Day of Week
Timer Mode
Run Date
Stop Date
Run Time 1
Stop Time 1
Run Time 2
Stop Time 2
Memory
Delete Last
Purge All Data Files
Allocated IDs
Create EEPROM Backup
a - Current time, date, and time of next
action
b - Timer mode status and settings
a - Memory status & current
instrument record information
b - Overall record status
Power Monitor
Display Power Status
Power Settings >
-Power Off Mode
-Auto-Off Time
-Standby Time
-Backlight Time
-Backlight
-LCD Contrast
-External Power
-Min Battery
Activate Battery Charger
Type
Battery and external power status, battery
type, and internal temperature
Communication
Baud Rate (300 - 115 K)
Serial Address
Flow Control
Modem>
-Modem Mode
-Dial Out Mode
-Phone #
-Monitor Number
-Modem Init
Lists command characters received and
data characters sent by the instrument. Also
shows the current standby timer status. The
serial port and display are turned off when
the timer reaches 0.
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3-19
About
To access information about the System 824 use the u or
d key to select About from the Tools menu, then press the
c key. The following screen appears:
Instrument model number
Instrument serial number
Internal firmware revision number and date
Internal SLM firmware revision number and date
The About-a display shows the instrument’s model number
and serial number as well as the firmware revision number
and date.
The revision number indicated by
“REV:” is changed when any
firmware code change is made. The
revision number indicated by
“SLM:” is changed only when a
firmware code modification is made
that affects the accuracy of any SLM
measurement data, and is used as an
indicator to those who use third
party verification (NIST or PTB,
etc.) of instrument performance that
testing should be performed.
About Settings edit mode can also be
edited by pressing the c key from
the
About
display
screens
(previously described).
Pressing the rkey moves to the About-b screen. The following appears:
The About-b display shows the instrument’s custom name
and title fields printed on System 824 reports. The fields are
generally set to the owner’s name and address. The name is
displayed at “power on” and printed on reports to customize
them to your business.
To modify the About settings, use the u or d key to
select About from the Tools menu, then press ther key.
The About setting offers three Name fields and one Title
field for use on System 824 reports.
Company Name, Address Line 1, Address Line 2- There
are three lines available for user specific data. Each field
provides 30 alpha/numeric characters, and is used to
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Company name and address
(Customized by user)
describe the instrument or the organization to whom it
belongs.
Title - Like the Company Name field, the Title field is capable of holding 30 alpha/numeric characters. It allows you to
title the ID (Instrument Definition) you have created, and to
describe your measurement.
Date Format - Displays the date in Normal or ISO-8601
format. Normal has the form of ddmmmyyyy and ISO-8601
has the form yyyymmmdd where dd is the two digit date of
the month 1 to 31, mmm is the month (i.e. JAN) and yyyy is
the year (i.e. 2000).
See the section “Any Impulse
Format” on page 5-8 for optional
Takt views.
Takt - Enables Takt functionality to give you taktmaxmal
values.
Pressltwice to exit the menu.
Pressing therkey again moves to the About-c screen. The
following screen appears:
The About-c display shows the system’s currently available
instruments. Additional instruments can be added to the Sys-
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Front Panel Keys; Functions and Menus
3-21
tem 824 through firmware upgrades as they become available.
Checked instruments are installed and available for use. The
number of demos used is indicated. Only 20 demos are
allowed. When “demos used” equals 20, options not purchased are no longer available for use. If you have found
them useful, they can be installed permanently without
restrictions. Call Larson Davis for details.
Calibration
To calibrate the System 824, or to view previous calibration
information, use the u or d key to select Calibration
from the Tools menu, then press the c key. The following
screen appears:
Date and time of the last calibration check
The level detected during the last check
Date and time of the last calibration change
Offset currently in use to calibrate the levels
The Calibration display shows the date and time of the last
calibration change and the offset being used to calibrate the
levels. It also shows the date and time of the last calibration
check and the level detected during that check.
To utilize the calibration tool or modify the Calibration settings, use the u or d key to select Calibration from the
Tools menu, then press therkey. The Calibration menu
provides the following settings:
Check - Activates the calibration check (level verification)
process.
Change - Activates the calibration change (adjust) process.
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Cal Level - Enables the user to enter the sound pressure
level generated by the calibrator.
Calibrator S/N - Enables the user to record the serial number of the calibrator (for reference).
Noise Floor - Enables the user to enter a noise floor value.
Optimum values will depend on the type of measurement
being performed. For a more detailed description, See
“Entering the Noise Floor Values” on page 9-4.
Clock/Timer
To display the time and date, or to view the timer settings,
use the u or d key to select Clock/Timer from the
Tools menu, then press the c key. The following appears:
Current time
Current day of the week and date
The time of the next timer function
The Time-a or clock display shows the current time, day of
the week, date and the time of the next timer action.
Pressing therkey again moves to the Time-b screen. The
following appears:
The currently-selected timer mode
The run and stop dates
The first run and stop times
The time of the next timer function
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The Time-b or timer display shows the current timer programming including the mode and the appropriate run and
stop times and dates.
Clock/Timer Settings can be
changed by pressing the c key from
the Clock/Timer display screen.
To modify the Clock / Timer settings, use the u or d
key to select Clock / Timer from the Tools menu, then press
therkey. A screen similar to the following will appear:
The clock in the 824 uses a 24 hour
format with hours 0 through 11 being
a.m. and hours 12 through 23 being
p.m. For example, 5 p.m. will be
displayed as 17:00:00.
With the Clock / Timer menu you set the instrument's clock/
calendar and timer. The first three menu items allow you to
set the current time, date, and day respectively, while the
remaining items (Run/Stop Date, Run/Stop Time 1, Run/
Stop Time 2) allow you to control the timer function.
IF the date has not been set (month
shows as???) then the message
“Time not set!” will be shown when
the Run key is pressed.
Current Time / Date - To set the current time and/or date,
highlight the desired item (i.e. Time or Date) and then press
therkey. Modify the setting using thelorrkey to
select the digit desired to modify, then use theuor d
key to modify.
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Day Of Week - Allows you to change the current day of the
week. Use the u or d key to highlight the desired day,
then press the c key to select.
Timer Mode - The timer is used when you want to have the
824 automatically turn on, gather data, and stop at pre-determined date(s) and time(s). The System 824 has four timer
modes automating the start and end of measurements:
Off - The timer is disabled.
Block - The timer will automatically turn the
instrument on and initiate a single measurement
beginning at a certain time on one day and ending
at a certain time on the same or another day.
NOTE: If the run time is later than the
stop time, then a measurement will start
on the stop date and end at the stop time
on the date AFTER the stop date.
1/Day - The timer will automatically turn the
instrument on and initiate one run/stop cycle per
day from the run date until the stop date.
2/Day - The timer will automatically turn the
instrument on and initiate two run/stop cycles per
day.
The three “enabled” modes (i.e. 1/Day, 2/Day, and Block)
use the dates set by the Run Date and Stop Date menu items
to determine the range of “valid” days on which to make
measurements.
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Run Date - Specifies the starting date to take measurements.
Stop Date - Specifies the date to end the measurement and
disable the timer mode.
Run Time 1 / Stop Time 1 - These settings allow you to
specify the beginning and ending times of a measurement.
NOTE: If you have selected the Block,
1/Day or 2/Day mode, the timer will
automatically turn the instrument on one
minute prior to the run time.
Run Time 2 / Stop Time 2 - These settings are used to specify a second measurement’s beginning and ending time in
the 2/day timer mode.
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Memory
To access the Memory display, use the u or d key to
select Memory from the Tools menu, then press the c key.
The following appears:
Available memory (as a percentage of total data
memory)
Available memory (in bytes)
Number of various types of history records for a
given ID (SSA in this example)
For detailed information on the
usage of memory (e.g. bytes for each
type of record stored), see “Memory
Usage” on page E-1
The Memory-a display shows the amount of memory available for storing data. This information is given both in bytes
and as a percentage of the total memory that can be used for
storing data. (This “total memory” does not include the
memory allocated for ID registers.)
Only those records enabled for the
active instrument type are displayed.
In addition, the Memory-a display shows the number of previously-stored records (of various types) for the active ID.
Pressing therkey again moves to the Memory-b screen.
The following appears:
Available memory (as a percentage of
total data memory)
Available memory (in bytes)
Total data files in memory
Number of setup registers allocated for storing
instrument definitions (IDs)
Total memory, including both data and setup register
memory
The top portion of the Memory-b display shows the same
“available memory” information as in the Memory-a display. In addition, the Memory-b display shows the number
of data files in memory; number of setup registers allocated;
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and the total amount of memory, including that memory
allocated for setup registers.
Memory Settings can also be
accessed by pressing the c key from
the Memory display screen.
To modify the Memory settings use the u or d key to
select Memory from the Tools menu, then press ther key.
See next page for detailed
information on the “Delete Last”
feature.
Delete Last - The Delete Last feature will allow the user to
delete the very last record stored in memory from any instrument type. To delete the last stored record, highlight Delete
Last and press the Check c key.
“Purge All Data Files” is also
available from the reset menu under
the RESET R key.
Purge All Data Files - Pressing the ror c key when the
Purge All Data Files menu item is highlighted, allows you
to purge all data files in memory. This clears the memory.
The default value of this setting is 10
allocated setup registers (which uses
5120 bytes of memory). The System
824 has ten permanent ID registers.
These pre-defined ID registers
cannot be changed or deleted and do
not reduce the amount of data
memory available. They are to be
used primarily as templates for new,
user-defined IDs.
Allocated ID’s - Determines the number of setup registers
that are allocated in memory for storing IDs. In essence, this
setting determines how much memory is allocated for storing instrument definitions. Setting this to a higher value
allows more IDs to be created, but reduces the amount of
memory available for data storage by 512 bytes per allocated
ID.
Important: In order to not lose your
customized settings in the event of
memory loss or firmware upgrade,
follow these steps.
1. Alter the permanent IDs as desired and save your
customized setting using a name of your choice.
Create EEPROM Backup - Stores the most recently used
SSA, ISM, and LOG IDs so that they may be recreated in the
event of a memory loss.
2. Enter the unit Name and other system settings in the
TOOLS>About menu
3. Bring your favorite ISM, LOG and SSA ID to the top of
the SETUP ID menu by selecting them one at a time. Alter a
permanent ID and save your customized setting using a
name of your choice.
4. Store these settings permanently using the TOOL>Memory>Create EEPROM Backup menu item.
Your settings will not become permanent.
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Repeated whenever you update any of the system settings or
IDs that you want to be permanent.
Deleting Stored Data
Delete Last Function
The Delete Last feature will allow the user to delete the very
last record stored in memory from any instrument type. It
also allows you to recall a file, delete individual records
within that file, run the instrument again and append new
data to memory. Essentially the record is unstored from
memory.
824 Memory Structure
The memory structure of the 824 is a forward and reverse
linked list. This means that for each type of data there is a
pointer to the first record and a pointer to the last record and
that each record points to the next record and the previous
record. This structure makes the memory very efficient
(compared to fixed sector, file allocation table based memory structures) and sequential forward and reverse data
retrieval is very fast.
This memory structure does not allow us to delete data in the
middle of used memory in a way that would allow it to be
reused. However, there is no problem deleting data from the
last to the first.
Deleting the Last Stored
Record
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Step 1
To delete the last stored record, press the TOOLS
T key to access the TOOLS menu. The following menu appears:
Step 2
Highlight “Memory” and press the rightrarrow
key.
Front Panel Keys; Functions and Menus
3-29
Step 3
Highlight “Delete Last” and press the Check c
key.
If “View Back” is selected you will
be returned to the last view screen
displayed.
If nothing is selected after a 30
second time period, this screen will
disappear and return to the previous
display.
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This display shows the last record that was stored along with
the date and time of the data, the instrument type it is
recorded for, the bytes used by that record and how much
memory is available.
Step 4
Press the Check c key to delete this file. The following menu will appear:
Step 5
Highlight “Delete” and press the Check c key.
The record is deleted. If the last record was a data
file then the following choices will appear:
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DEL - Choosing “DEL” will erase the file and all of its contents.
Choosing “Open” also allows you to
delete individual records from the
file after it has been opened. See the
next page for instructions on
deleting individual records. In
essence this will UNDO the storing
of a data file.
Open - Choosing “Open” recalls the file into memory, the
File record is deleted, and the data in memory marked as if it
had never been stored. This allows you to run the instrument
again and store the old data and the new data just acquired
into a new file.
Deleting Individual Records
After selecting “Open” in Step 5 above, the file record is
deleted and now you are allowed to look at each individual
record and decide whether to delete or store it with new data
appended to it. Follow these steps to delete individual
records:
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Cancel - Choosing “Cancel” cancels you out of the Delete
File function and returns you to the previous display.
Step 1
The last display that was viewed will appear after
selecting “Open”.
Step 2
Press the TOOLS T key and the following
appears:
Step 3
Highlight “Memory” and press the rightrarrow
key to access the “Delete Last” function.
Front Panel Keys; Functions and Menus
3-31
Step 4
Highlight “Delete Last” and press the Check c
key.
The records will appear one at a time. Below are examples
of some of the records.
To delete them press the Check
appear:
c key. The following will
With “Delete” highlighted, press the Check c key again to
delete the record. The next record will appear. Continue this
process until you have deleted all of records that you don’t
want.
Power Monitor
This menu option allows adjustment of the auto-power off,
the contrast (or viewing angle), turns the backlight on or off
and adjusts settings that control the power-conservation features. Refer to the section “v POWER key” on page page
3-3 for a full description of the Power Monitor settings. In
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the following example of the Power Monitor display, the
battery indicates 3.49 V while charging. When the instrument is running, this will typically be 3.6V or less.
Communication
The Communication display shows the status of the serial
port (i.e. how many minutes until the standby mode is automatically enabled) and the last characters received and transmitted and is used when troubleshooting communication
problems and as an aid when writing programs to control the
instrument.
To access the Communication display, use the u or d
key to select Communication from the Tools menu, then
press the c key. The following appears:
Indicates current address
status.
Indicates 824 is ready to
receive commands
Shows the last characters received
(none in this example)
Shows the last characters sent (none in
this example)
Indicates controlling
device (computer,
modem, etc.) is ready
to receive data
Shows the minutes of inactivity
remaining before the serial interface
powers down
This menu can also be accessed by
pressing the c key on the
communications display.
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To access the Communication settings, use the u or d
key to select Communication from the Tools menu, then
press ther key. A menu similar to the following appears:
Front Panel Keys; Functions and Menus
3-33
The printer has its own baud rate for
printing reports and is not affected
by this setting.
Baud Rate - Speed at which the System 824 communicates
with controlling devices (computer, modem, etc.) through
the serial port. The baud rate has a range from 300 to 115200
baud.
Default is set to the value of the last
2 digits of the serial number and can
be set within the range of 1 to 100.
Serial Address - Address of instrument. This setting identifies the instrument within a network of instruments by
assigning it a network or serial address.
Use the right and left arrow keys to
toggle between the Communication
display and a list of Errors or
Warning Messages. These messages
are useful when troubleshooting I/O
command problems.
Flow Control - Flow control of the serial connection. Flow
control can be changed to None, Hardware, Xoff, or Both.
Flow control prevents the loss of data when either the instrument or controller’s input buffer becomes full. Hardware
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flow control is recommended.
See the section “Modem Control
Mode (All Instruments)” on page A66 for more detailed information on
modem communication.
Modem Mode - Turns the modem mode on or off to allow
communication to a telephone modem.
Dial Out Mode - The 824 will dial out on an Exceedance or
an Alarm or both.
Phone Number - The 824 will dial the phone number
entered here on the events selected in the dial out mode.
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Front Panel Keys; Functions and Menus
3-35
Monitor Number - The monitor number is used to identify
which 824 is being queried and is sent with the 824’s initial
announcement.
Modem Init - The modem initialization string is entered
here.
Initialize - The modem initialization string is sent out the
RS232 port.
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P Print Key
Refer to the section “Printing
Reports” on page 8-2 for more
information on printing.
The P PRINT key displays the printing options menu.
These options enable printing of graphical and tabular data
reports directly from the instrument to a serial printer. You
can create high-resolution presentation-quality reports when
printing to a laser printer because of the instrument’s PDL-3
(Page Description Language) capabilities. Draft-quality tabular data reports can also be printed on virtually any serial
printer.
The Print menu provides the ability to output reports containing all the data gathered for the measurement to an
attached printer. The main Print menu is activated by pressing the P PRINT key.
The Print menu changes depending
upon the specific instrument being
used.
With an appropriate printer connection, you can print a number of reports. The “Recall Format” sub-menu option is used
to enable various reports. Do this by highlighting the corresponding menu item and pressing the c key.
Use “Tailored Report” to print the custom reports that are
defined as part of an instrument definition (SSA and LOG
IDs only).
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3-37
Use the Customize sub-menu to further customize the report
settings. In this sub-menu you can select the specific elements to include in the report and also the various data
ranges for histograms, time histories, etc. To access this submenu, highlight Customize and press ther key.
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CHAPTER
4
Quick Start
The System 824 instrument provides simultaneous measurements of sound pressure level using Fast, Slow, Impulse,
Peak and Leq detectors with A, C, and Flat weighting covering a large dynamic range of greater than 105 dB in the LOG
and ISM instrument and 80 dB in SSA instrument.
With the System 824 calibrated, the desired instrument
definition selected, and its associated settings properly
configured, you can easily take a measurement and examine
the readings from the data collected. Taking an actual
measurement with the System 824 is as easy as pressing the
s (RUN/STOP) key.
This chapter helps users begin using the System 824
immediately. This chapter will present the following:
•
Turning on and Calibrating the System 824
•
Taking Measurements and Storing Data
•
Recalling Stored Data
•
Deleting Stored Data
•
Selecting and Modifying Instrument Definitions (IDs)
Turning On and Calibrating the System 824
This section guides you through the process of turning on
and calibrating the System 824.
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Quick Start
4-1
This screen displays three lines of
user information which may be
defined as name and address
settings. You can use the 824 Utility
Software to input this information.
This display also shows the serial
number of the instrument and the
firmware version and date. The
System 824 then loads the last
instrument definition (ID) selected.
Step 1
Pressing the v POWER key for 1
second turns the power OFF.
Step 2
Power off prior to changing
microphone or preamplifier to avoid
possible damage of sensitive
electronics due to high voltage
spikes.
Step 3
This screen shows you the current
power source, battery level, and
external power voltage.
Step 4
Step 5
4-2
Turn on the System 824. To do this, press the v
key (located on the left side of the key pad). By
pressing this key, the Larson Davis logo appears
while a number of tests are performed. The following screen then appears for a few seconds:
Check the battery level. After the System 824 is
turned on, you can check the battery level. To do
this, press the v POWER key momentarily. The
following screen appears:
Calibrate the instrument. To do this, press the T
TOOLS key. The following menu appears:
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NOTE: The output level specified by the
calibrator manufacturer will be at standard temperature and pressure. In practice the level is a function of temperature
and static (barometric) pressure, so a
corrected level should be used. Similarly,
the sensitivity of the microphone itself is
a function of temperature and static pressure. For directions on compensating for
temperature and static pressure during
calibration, see “Correction of Calibrator Output Level” on page 2-17.
Step 6
Using the dkey, highlight the Calibration
menu item, then press the c key. The following
screen appears:
Step 7
The value of Cal Level (3rd item on the screen)
must be set equal to the output level of the
calibrator to be used for the calibration (typically
94 or 114 dB). If the value indicated is not equal to
this value, use the d key to highlight the Cal
Level menu. Press the c key, use the horizontal
and vertical arrow keys to input the correct value
and press the c key to make the change.
Step 8
Place the calibrator over the microphone. Using
the d key again, highlight the Change menu
item. Press the c key to start the Calibration
process.
Step 9
When prompted by the message shown below,
press the c key to continue the Calibration
process. If you wish to abort the calibration
procedure, rarrow key to select Cancel and
press the c key.
Step 10 While the system is stabilizing, the measured level
is indicated on the left of the screen and the
difference between the measured level and the Cal
Level Setting are show on the left and right sides
of the display, as shown below, along with the
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Quick Start
4-3
message Wait indicating that the calibration
process in underway and should not be
interrupted.
Step 11 When the calibration is complete, the message will
change to Stable, after which the following display
will appear to prompt the user to decide whether
or not to calibrate the High Range as well. If you
decide to calibrate the High range as well as the
Normal range, there will be a forty second delay
while the instrument stabilizes at the High range
setting.ll.
High Range Calibration
Note: When using a prepolarized
microphone, during setup Electret
should have been selected as the
Transducer. The High Range is not
available when using a prepolarized
microphone,
so
the
prompt
concerning calibration of the High
Range will not appear.
4-4
When the High Range is calibrated, the microphone bias
voltage is reduced from 200 to 20 volts. This reduces the
sensitivity of the microphone by 20 dB. As a result, the
measured level indicated on the left of the display during the
stabilization process should be 20 dB less than the Cal Level
value.
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Taking Measurements and Storing Data
This section provides examples of how to select an
instrument ID, take a measurement, and store the resulting
data.
SLM&RTA Measurements
NOTE: A solid black box indicates that
the 824 is stopped with data, and a hollow box indicates that the 824 is stopped
with no data present.
Whether using the SSA, ISM, or LOG instrument, the SLM
is one of the most common functions used in the System
824. The following example explains how to record and
store a measurement in the SLM mode of the SSA
instrument.
If the 824 is already using the SSA
ID, there will be a ‘>’ to the left of
it’s name on the second menu line.
Step 1
To activate the SLM&RTA SSA instrument, press
the S SETUP key. A menu similar to the following appears:
When changing from one ID to
another you will be prompted to save
your data if you have not already
saved it. If you do not save your data
at this point, any measurement
readings you have taken will be lost.
If this is your first time using the
System 824 and you have not set up
any ID’s, or have not taken any
readings that need to be saved, select
“No”.
Step 2
Press the uordarrow keys to highlight the
SLM&RTA SSA item and press the c key to
select it. The last used SLM+RTA display appears:
Step 3
At this point, if you want to view a display other
than the one shown, press the V VIEW key. Use
the u or d keys to highlight the desired
display. For this example, highlight SLM and
press the c key to select it. The SLM display of
The bolded SLM text on the SLM
view screen indicates that this is the
SLM view of the SSA instrument. Any
of the SSA displays can be active
while taking a reading.
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Quick Start
4-5
the SLM+RTA instrument shown in step 2 will
appear. The Sound Level Meter with Real-Time
Spectrum Analyzer is now ready to use.
The instrument display shows a
running symbol (upper right hand
corner) when the instrument is
actively taking measurements.
Step 4
To take a sample reading, press the s RUN/
STOP key. A screen similar to the following
appears:
Let the instrument continue to take measurements
for about one minute. Make some noise and watch
the results on the graph.
Step 5
Press the RUN/STOP key to stop the
measurement.
Step 6
To store the current measurement readings, press
the D Data key. Select Store File and press the
c key. This will store the measurement’s data.
The screen shows a black box
symbol in the upper right hand
corner indicating that the instrument
is stopped and not taking a
measurement.
If you attempt to store data while a
measurement is still running a
warning
will
be
displayed,
indicating that the measurement
must first be stopped.
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Step 7
To turn off the instrument, press and hold the v
key until you are prompted to release it. The
instrument then turns off.
NOTE: You may want to repeat the process of running a measurement, stopping, and storing its data a few times so
that you will have several samples of
stored data to choose from when trying
this exercise.
Viewing RTA Displays during a Measurement
While taking measurements you can view the instrument’s
different displays. This section provides examples of
viewing the SSA instrument’s four RTA displays which
include:
•
RTA Live
•
RTA Leq
•
RTA Max
•
RTA Min
Do the following to view the RTA displays:
Step 1
Select the SLM&RTA (SSA) instrument from the
Setup menu and press RUN/STOP s to begin taking a measurement as explained in the
“SLM&RTA Measurements”section found on
page 4-3.
Step 2
While the measurement is running, press the V
View key. The following screen appears:
If you select the RTA Live item with
the rarrow key instead of the c
Check key, you will be given the
option to view the display in
graphical or Tabular mode.
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Quick Start
4-7
Step 3
Use theuanddarrow keys to highlight the
RTA item and press the Check c key to select the
RTA displays. A screen similar to the following
appears:
Step 4
Use therandlarrow keys to change the
selected frequency. As the selected frequency is
changed, the SPL for that frequency will be
displayed in the upper left corner. Additionally,
the cursor bar will move along the graph to the
position that corresponds to the SPL graphical
display for that particular frequency.
Step 5
Press thedarrow key to change to the RTA Leq
view. A screen similar to the following appears:
Step 6
Use therandlarrow keys to change the
selected frequency. As the frequency is changed,
the Leq for that frequency will be displayed in the
upper left corner. Additionally, the cursor bar will
move along the graph to the position that
corresponds to the Leq graphical display for that
particular frequency.
Step 7
Press thed arrow key to change to the RTA
Max view. A screen similar to the following
appears:
The RTA Live screen shows a
graphical display of the sound
readings over a range of frequencies.
The SPL for the selected frequency is
displayed in the upper left corner.
The frequency, as selected by the
vertical cursor, is displayed in the
lower left corner.
As the frequency is changed the
cursor (vertical bar) will move
accordingly across the graphical
display,
highlighting
the
corresponding graphical sound
reading. Additionally, the digital
frequency display will also change
as will the digital readout of the
sound measurement for the newly
selected frequency.
The RTA Leq view shows a graphical
display of average sound exposure
for the measurement time. The LEQ
for the selected frequency is
displayed in the upper left corner.
The selected frequency is displayed
in the lower left corner. When the
cursor is moved to the far right side,
the broadband Leq is shown
numerically and the cursor is no
longer displayed (as shown here).
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The RTA Max view shows a
graphical display of the Live
spectrum of the maximum broadband
level since the last current reset.
This is the minimum level obtained
for each frequency since the last
current reset.
Step 8
Use therandlarrow keys to change the
frequency level being displayed.
Step 9
Press thedarrow key to change to the RTA Min
view. A screen similar to the following appears
Step 10 Use theuanddarrow keys if you want to
move back and forth between the different RTA
screens.
Step 11 Press the RUN/STOP s key to stop the current
reading.
If you attempt to store data while a
measurement is still running, a
warning
will
be
displayed,
indicating that the measurement
must first be stopped.
Step 12 Press the D Data key. Select Store Data and
press the c key to store the measurement’s data.
Recalling Stored Data
Measurement data that has been stored can be recalled for
review at any time. To recall a data file, do the following:
Step 1
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Press the D Data key and a screen similar to the
following appears:
Quick Start
4-9
Use theuup andddown arrow keys to
highlight “Recall Files” and press the c check
key. The following appears:
When recalling a data file, the
System 824 will automatically switch
to the instrument that the data file
was stored as (i.e. from Logging to
SLM&RTA).
Step 2
The Data Files screen shows the
currently selected record number, the
ID used to take the measurement, the
start/stop dates and times, and the
total bytes used by the record.
A summary of each data file can be viewed to determine if it
is the desired measurement. To view each data file summary
use the uup and ddown arrow keys.
Step 3
You can recall the selected Data File by pressing
the c Check key. The following screen appears:
The Data Files check menu includes the following:
4-10
Menu Items
Description
Recall Data
Recall the stored data file’s measurement.
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Beginning
Displays the Data File Summary of
the first stored data file.
Ending
Displays the Data File Summary of
the last stored data file.
Find
Allows you to find and display a Data
File Summary by entering its associated Data File Number.
Purge All Data
Files
Gives you the option to completely
remove from memory all stored data
files.
Selecting and Modifying Instrument Definitions (IDs)
As explained in the section “System 824 Setups or
Instrument Definitions” on page 2-1, the way to prepare the
System 824 for a measurement is to select an existing Setup
or Instrument Definition (ID) from the list which appears on
the display after pressing the Setup Key S and either use it
as-is or modify it to suit the requirements of the
measurement to be performed. In this section, we will
explain in general how an ID is modified and stored using
the Setup Menu of the System 824. More detailed
descriptions for specific Instrument Types (e.g. ISM, LOG,
or SSA) will be provided in later chapters. When a PC is
available, the 824 Utility software is a very powerful tool for
creating and storing new IDs and uploading them to the
System 824 for use.
The Setup Menu
Pressing the S Setup key will produce a display similar to
the following:
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Quick Start
4-11
The Active ID
The first item in the list is the Active ID, which will be
highlighted. If the user exits from the Setup Menu by
pressing either S (a second time) orl, the instrument is
ready to perform a measurement as defined by that Active
ID.
Active ID
Name of original ID
Following the Active ID is a list of the available IDs. In
most cases, the first ID in the list will have the symbol “>” to
the left, indicating that the Active ID was originally defined
by selecting that ID. Thus, the name of the Active ID and
this ID will be the same. If there is an asterisk “*” to the left
of the Active ID, it indicates that modifications have been
made to the Active ID since the selection of the ID below it,
so they may no longer be the same. If there is no asterisk,
then the Active ID and the one below remain identical.
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Asterisk to indicate that
active ID has changed.
There is one other possibility which should be mentioned.
When a stored data file is recalled, then the ID stored with
that file becomes the Active ID. Since the ID which was
used to perform the measurement at that time may have
since been modified or even deleted, a tilde “~” will appear
to the left of the Active ID to indicate that it is
approximately the same as another ID in the list.
Menu Scrolling
There may be more items in a menu than can be shown in a
single display. To the right of any menu window, there will
be a vertical window within which there will be vertical bar.
If this vertical bar extends from the top to the bottom of the
vertical window, then all items in the list are shown in the
display. If the vertical bar does not cover the length of the
vertical window, this means that there are more items than
can be displayed and that those presently being displayed
fall within the portion of the vertical window covered by the
vertical bar. In the example of the Setup Menu, it can be seen
that there are more items than can be shown in one display
and that those presently being displayed are at the top of the
list. Use the upuanddarrows to scroll through the list
and note how the vertical bar moves to indicate which
portion of the list of menu items is presently being
displayed.
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Quick Start
4-13
Bar that indicates
that there are more
lines in this menu.
Permanent IDs
In the list of available IDs, those with a “P” to the left of the
name are permanent IDs provided upon delivery. These can
be selected, modified and used for a measurement, but the
name must be changed when the modified ID is stored so
that it does not conflict with the names of any permanent
IDs.
‘P’ indicates
permanent ID.
Write-protected IDs
Those with a symbol of a padlock to the left are user-defined
IDs which have been write-protected. Like the permanent
IDs, these can be selected, modified and used for a
measurement, but the name must be changed when stored.
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Indicates ID is write
protected
Preparing for a Measurement
If data has been taken, this prompt
will be shown. Press the check c
key to reset data and edit the setting
If the Active ID will provide the desired measurement, press
either the Setup S key or l to exit from the Setup menu.
The System 824 is now ready to perform a measurement
according to the Setup represented by the Active ID.
If the Active ID is not satisfactory for the measurement, the
following options are available:
•
1. Modify the Active ID as required
•
2. Select and use a different ID (make it the Active ID)
•
3. Select a different ID, make it the Active ID, and modify it as required.
Selecting a Different ID
Use the dand ukeys to highlight the desired ID and
make it the Active ID by pressing the c Check key. This
will activate that ID, exit the Setup menu, and display the
main data view. The instrument is ready to perform a
measurement by pressing s Run/Stop.
Accessing the Settings Menu
It is within the Settings menu and its associated Sub-menus,
that the settings associated with the measurement are
defined. Sound level measurements are made in the ISM
LOG, and SSA Instrument Types, so all of these will include
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Quick Start
4-15
selections of RMS and peak detectors and broad band
frequency weighting. IDs based on the LOG Instrument type
will include parameters associated with automatic data
storage such as Interval and Time History periods and
threshold levels for triggering Exceedance Event data.
Report settings are also included in the Settings menu when
appropriate.
The following example will be used to illustrate the general
structure and utilization of the Settings menu and submenus. Please follow this on your instrument. Since all
versions of the System 824 include the SSA Instrument
Type, we want to select the permanent ID SLM&RTA (SSA)
as the Active ID. Press S to open the Setup menu.
Step 1
If the Active ID in your instrument is an unmodified version of SLM&RTA (SSA), press c.
Step 2
If the Active ID in your instrument is anything
other than SLM& RTA (SSA), then highlight
SLM&RTA (SSA) and press c to make it the
Active ID.
Step 3
If the Active ID in your instrument is a modified
version of the SLM&RTA (SSA), indicated by an
asterisk to the left of the name, highlight
“>SLM&RTA (SSA), press c, and in response to
the message “Active ID has changed. Save?”, use
rto highlight “No” and press c to make it the
Active ID.
Step 4
Press S to display the Setup menu with
SLM&RTA (SSA), unmodified, as the Active ID.
>
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Accessing the Settings Menu to Initiate Editing or Modification
As mentioned above, the first item on the list, highlighted, is
the Active ID. The message “Edit Settings”, along with the
symbol “>” to the right, indicates that one should press
rin order to view or edit the Active ID. In many cases,
the c Check key will accomplish the same result. This will
produce the Settings menu list as shown below.
Note that all of the items in this list, with the exception of
the first, Title, have the symbol “>” to the right indicating a
sub-menu. In order to illustrate the Settings menu structure,
please perform the following steps to set the SLM Weighting
function.
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Step 1
Usedto highlight SLM
Step 2
Pressrto produce the SLM sub-menu
Quick Start
4-17
Step 3
Usedto highlight Weighting (note that the
present selection is “A”)
Step 4
Pressr to open SLM Weighting Selections
menu
Step 5
Usedto highlight “FLT”
Step 6
Press c to select FLT as the new SLM Weighting
For the purpose of continuing with this example later in this
chapter, please do not press any keys.
Although we will not do this in the present example, we
could highlight Detector noting that it is presently “SLOW”,
pressrto open a window listing the SLM Detector
selections, highlight “FAST” and press c to select it as the
new SLM Detector.
Regardless of the Instrument Type, one can modify any of
the available parameters by selecting the proper Setup menu
item, then the proper sub-menu item, then making a
selection and pressing c.
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Once one or more modifications have been made, the user
can follow one of three procedures:
•
Setup S will close the menu, remembering its location
the next time it is opened.
•
Use the rightlarrow key to step out one menu at a
time.
•
Press v power to close the menu and reset the menu
position.
In either case, the instrument will be ready to perform a
measurement. The major difference is that the second
method, backing out by a sequence oflkeys, possibly
interspersed withuanddkeys, leaves a memory of the
path used to withdraw.
To better understand what happens when we back out of the
Setting menu structure using repeated presses ofl,
consider the following diagram illustrating the actions which
have been taken so far in the example above.
In this particular instance, when therkey was used to
move from the Settings menu to the SLM sub-menu and
from the SLM sub-menu to the Selections menu, the item
highlighted was not the first in the list. Observe that when
c was pressed to accept the selection of “FLT for the
frequency weighting, upon returning to the Weighting submenu, the 2nd item was highlighted, just as it had been
previous to entering the Selection menu usingr.
Continuing the example, presslto exit from the SLM
sub-menu to the Settings menu and note that the 2nd item is
highlighted just as it had been earlier whenrwas used to
move from the Settings menu to the SLM menu.
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Quick Start
4-19
Essentially, when thelorrkey is used to move from a
Menu, Sub-menu, or Selection menu, a pointer in the menu
is set to the item which is highlighted at that time. If in the
process of continuing with the editing process a Menu is
accessed once again using thelorrkeys, the item
highlighted is determined by that pointer.
Continuing the example, uselto exit completely from the
Setup menu. Enter the Setup menu again by pressing S and
use three consecutive presses of rto display the Settings
menu, SLM sub-menu and Selection menu. In each case, the
highlighted item is as it had been when previously exiting
from that Menu. To the experienced user, this can be a
valuable feature. Suppose, for example, one wished to use
the Setup menu to quickly switch between choices of
frequency weightings. Using thelandrkeys alone one
could access the desired Selection menu without the need to
usedto move the highlight down from the first item.
If one chooses to use thelandrkeys to move between
Menus and prefers to enter each Menu with the first item
highlighted, simply use theukey to highlight the first item
in a Menu before exiting using thelorrkey to exit.
If you have been using the arrow keys to move between
Menus and menu items and you feel you have gotten lost, it
is possible that you have entered a Menu where you do not
recognize the displayed items because the highlighted item
is rather far down the list. Try using theu key to move the
highlight up to the first item and you may recognize where
you are. In general, the items further down the list are for
more advanced features and are less important for simple
measurements.
Setting Control in the SLM View
SLM settings can be adjusted from the SLM View screen. To
activate the SLM view screen, turn on the System 824, press
the V View key, highlight SLM, then press the c Check
key.
While viewing simple sound level meter data, settings can
be adjusted “on the fly” (without leaving the current
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display). The following table describes the keys that are
used to change settings:
Key
Action
d
Moves to the next setting
u
Moves to the previous setting
lorr
Adjusts the current setting
c
Enters the setting
The following is an example of how to select the RMS
Detector within the SLM view:
Step 1
Press the u or d keys to highlight the current
RMS detector (Slow, Fast, Impl).
Step 2
Press thelorrkey to change the selection.
The table below shows how to use the arrow keys to
navigate through the settings on the SLM display.
ud
Detector
Slowr Fast rImpulse r
ud
Weight
A rCr Flat r
ud
Second Value
Leqr SELr Minr Max rPeakr
ud
Second Value Weight
Ar C rFlatr
ud
Gain or aRange
0r +10 r+20 r+30 r+40 r+50r
OR
Lowr Normalr
a. Range is used in the ISM instrument instead of gain.
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Quick Start
4-21
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CHAPTER
5
System 824 Views
This chapter introduces you to the various ways of viewing
measured data for a particular setup or ID of the System 824.
Specifically, this chapter covers the following topics:
•
Status icons
•
General views
•
SLM+RTA specific views
•
Logging SLM specific views
Status Icons and Indicators
When using the System 824 you will encounter a number of
different display views. Each display contains an instrument
status icon in the upper right hand corner of the display. This
icon changes according to the current state of the instrument.
System under range/near noise
floor indicator
Indicated weight under
range/near noise floor
indicator
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Latching
Overload
detector
Mode
System 824 Views
5-1
The following table describes the icons that may appear:
Icon
Description
Animated Running Figure - The
instrument is running and acquiring
data.
Solid Box - The instrument is stopped,
data available.
Open Box - The instrument is stopped,
and reset.
Open Box with small solid box Viewing a recalled file.
Solid Box with open box in middle OverAll or Current data are available
but not both.
Double Bar - The instrument is paused.
Play Symbol - The instrument is ready
to run (as soon as stabilization
completes).
Arrow-Under-Range/Near Noise Floor
Indicator -The instrument is under range
when the arrow is longer. The
instrument is near its noise floor when
the arrow is shorter. The system
indicator, in the upper right corner of the
display, will indicate when any A, C, or
Flat instantaneous Leq inputs are under
range or near the noise floor. The
indicated weight indicator, shown just
below the db/weight icon, will show
whether that particular weight is under
range or near the noise floor.
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Block with Dark background and Light
numerals-Defines upper and lower
limits of linearity range.
Bar and Play Symbol - The instrument is
in preview. Current SPL and peak levels
are displayed, but no data is being
acquired.
Animated Hourglass - The instrument is
stabilizing to ensure accurate
measurement.
Animated Draining Battery - The battery
is low, and the instrument will shut off
soon.
O.L. - The instrument has been
overloaded; measurement may not be
accurate due to an overload condition
having occurred some time during the
measurement.
Animated shrinking letter M - Indicates
that less than 10% of memory is
available when shown intermittently or
out of memory when shown
continuously.
Animated Clock - Indicates that the
automatic run/stop timer is active.
Currently overloaded
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System 824 Views
5-3
To set the noise floor level, go to the
“Tools” menu and highlight
“Calibration”. Scroll down to
“Noise Floor” and press the c key.
Enter the noise floor using the value
provided by the microphone
manufacturer’s specifications.
General Views
The System 824 presents measurement data in both
graphical and numerical/text formats for easy
comprehension. This section provides an overview of the
basic components of these display views. See the Chapter
"Using ID Setting Files" on page 7-1 for detailed
descriptions of the available settings contained within any of
the System 824 views.
After you have selected the SLM&RTA operating mode or
instrument ID, do the following to select the desired view.
Step 1
Press the V button and a screen similar to the following will appear.
Step 2
Use the u and darrow keys to highlight the
desired view.
Step 3
Press the Check c key and the desired view will
appear.
SLM Views
The SLM view is available to the
ISM, SSA, and LOG instruments.
5-4
The SLM view shows the SLM data with a graphic display
of Time History. In this graphical format, a running time
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history based upon 1 second Leq values is scrolled across the
screen showing the levels of the last fifty samples. New data
points correspond to the detector and weighting selected by
their respective settings. The larger digital display indicates
the SPL for the selected values of detector and weighting.
The smaller digital display indicates the level corresponding
to one of the secondary parameters which are being
measured concurrently.
The SLM view display consists of eight major components:
•
Display label
•
Selected detector
•
Current SPL reading
•
Selectable Leq reading
•
Weighting
•
Elapsed time
•
Status
•
SPL history graph
Display label
Status
detector displayed
Current SPL reading
Weighting displayed
Selectable reading
Elapsed time
1 sec Leq history
graph
Current SPL
The following is a brief description of each of these
components:
Display label - The Display label identifies the display. The
example above shows the SLM view for the SLM+RTA
Instrument ID.
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System 824 Views
5-5
Selected detector - The selection determines which
detector’s data (e.g. Fast, Slow, Impl) is to be displayed.
Current SPL reading - Displays the current SPL reading
(as does the level of the moving bar on the far right of the
SPL history graph). The frequency weighting for SPL can be
selected: A, C, or FLAT. The detector can be selected from:
Slow, Fast and Impl.
All combinations of detector and
weighting
are
measured
simultaneously. The detector and
weighting selected in the “Settings”
menu are for measurements such as
Ln and Interval broadband levels.
Selectable reading - This is used to view a second level
which can be Leq, SEL, Min, Max, or Peak.
Weighting - This selection determines which weighting is
being displayed for the SPL and selectable reading. When
the selectable reading is showing Peak, the weighting for the
Peak can be set to: A, C or Flat (independent of the current
SPL frequency weighting).
Elapsed time - Displays the current run time for the
measurement. It resets to zero when the R RESET key is
pressed, pauses when the p PAUSE key is pressed, and
continues when the p PAUSE key is pressed again. The
timer is displayed as mm:ss.ss, hh:mm:ss or hhhhh:mm.
Status - Status represents the state of the instrument (as
described at the beginning of this section).
SPL history graph - This shows one second Leq readings.
The far right bar displays the current SPL readings. As
readings are taken, they are placed onto the scrolling graph
from right to left every second. The time axis, in the SPL
history graph, shows time increasing from left to right.
You can use the arrow keys to select the detector, weighting,
secondary parameter to be displayed and gain or range as
shown below.
5-6
Key
Action
d
Moves to the next setting
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u
Moves to the previous setting
l or r
Adjusts the current setting
Detector
(Fast, Slow, Impulse)
Weighting
(A, C, or Flat)
Secondary Parameter
(Leq, SEL, Lmin, Lmax, Lpk)
Secondary Weighting
(A, C, or Flat)
Gain
(0, +10, +20, +30, +40, +50
Any Data View
The Any Data View presents a tabular display of SLM data
in three different formats.
•
Any Level Format
•
Any Impl (Impulse) Format
•
Any Time Format
Theuand darrow keys allow you to change the Any
Data format you are viewing. Thelandrarrow keys
move you through each of the Any Data formats’ available
displays.
Any Level Format
In this view, five different tables present SPL (Fast and
Slow), Lmax (Fast and Slow), Lmin (Fast and Slow), Leq,
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System 824 Views
5-7
SEL, and Lpeak measured with A, C and Flat weighting as
follows:
Any Impulse Format
In this view, three different tables present Impulse weighted
parameters alongside similar Fast weighted parameters
measured with A, C and Flat weighting as follows:
Additional views if TAKT
functionality is enabled.
See page 3-18.
Any Time Format
5-8
In this view seven different displays present the level, date
and time of Lmax (Fast, Slow, and Impulse), Lmin
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(Fast, Slow, and Impulse) and Lpeak measured with A, C
and Flat weighting as follows:
SSA Specific Views
The System 824 has various displays for the SSA
instrument. Understanding these displays lets you take full
advantage of this instrument.
In addition to the SLM and Any Data views described
earlier in this chapter, there are four spectral displays
available in the SSA instrument; the RTA Live
(instantaneous) spectrum, the RTA Leq or time weighted
averaged (since last reset) spectrum, RTA Max spectrum,
which is the spectrum time coincident with the maximum
value of the SPL during the measurement interval and RTA
Min, which shows the minimum level obtained by each
filter during the measurement interval. There are also
displays for the Interval History, the Time History, the Run
Log and for Ln Centiles.
Like all of the System 824 displays, these views are
accessed via the V View key as described earlier in the
“General Views” section of this chapter.
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System 824 Views
5-9
The following briefly describes the main views available to
the SSA instrument.
5-10
Menu
Items
Purpose
SLM
SLM data with graphic display of Time
History.
Any Data
Tabular display of SLM data
RTA Live
Real-time frequency analysis display
RTA Leq
Leq frequency analysis display since the
last reset
RTA Max
Frequency spectrum associated with the
highest SPL RMS level since the last reset
RTA Min
The minimum level recorded for each
frequency during the measurement.
Intervals
Shows an Leq spectrum, Max or Min
spectral data, a broadband Leq, Lmax,
Lmin, SEL, Lpeak and Spectral Lns for
each interval period.
SLM
Time
History
Shows the Leq for each time history period
in graphical form plus the selected
advanced T.H. items.
RTA Time
History
Live/Leq
Shows the spectral data for each time
history period.
Run Log
Displays the start and stop times/dates of
the active measurement
Ln
Centiles
Ln percentile levels exceeded ‘n’ percent of
the measurement time for broadband and
spectral data.
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To store interval spectral Ln levels,
set “Spectral Ln” to “Interval”,
enable Ln and Interval histories
and set “Intv Save Ln” to “Yes”.
SSA Displays
All of the following views can be accessed through the
View key when using the SSA instrument.
V
Additionally, the RTA Live, RTA Leq, RTA Max and RTA
Min can be easily switched between each other by using the
uordto move to any of the other views.
Therorlarrow keys can used to move the cursor.
SSA Displays Including 1/1 or
1/3 Octave Spectral Data
The following are examples of the graphical displays for the
RTA Live, RTA Leq, RTA Max, and RTA Min.
In the above views the cursor position (the vertical bar in the
graph) corresponds to the level and frequency values shown.
the left side of the display. The cursor or (frequency bar
position) can be changed by pressing therorlarrow
keys. As the arrow keys are pressed, the vertical bar moves
to the appropriate position and the frequency readout
changes accordingly.
Tabular SSA Views
The Tabular display can also be
accessed from the main View menu
by highlighting the desired RTA view,
pressing the r arrow key, and
then selecting Tabular from the
submenu that appears.
In addition to a graphical view, a tabular display is also
available for the RTA Live, RTA Leq, or RTA Max modes
which shows a tabular listing of the dB readings at specified
frequency levels in each of these spectra. To access the
tabular displays do the following:
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System 824 Views
5-11
Therand larrow keys move
you through a series of tabular
displays showing the current
spectra’s dB readings at each center
frequency.
Step 1
Press the c Check key while in the RTA Live,
RTA Leq, or RTA Max graphical views. The following menu appears:
While in the main tabular view, the
Step 2
Highlight Tabular using the u or d arrow
keys then press the c check key. A tabular display like the following screen appears:
Step 3
To return to the graphical view, press the c
check key and the following menu appears:
uandd arrows keys cycle you
through the different spectra’s (i.e.
RTA Live, RTA Max, and RTA Leq)
tabular displays.
Select “Spectrum” to view the graph again.
Time History Displays
5-12
The following are examples of the graphical displays for the
SLM Time History and RTA Time History Views:
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The up uand down darrow keys change the record
you are viewing. Therorlarrow keys change the
position of the cursor.
SSA Intervals
NOTE: SSA Intervals are only available
when the LOG option is installed.
See the section I"ntervals" on page
5-44 for a description of the
Interval-a
through
Interval-d
displays.
The Interval History shows a record of various sound
pressure data and spectral data (including spectral LNs)
gathered in time segments over the run time of the 824. An
example would be a measurement where data is gathered in
one hour time intervals over a 24 hour period.
Only Min or Max can be displayed.
The SSA instrument has 4 unique interval displays which
show the Max spectra (at the time the broadband level was at
maximum), Min spectra, which is a bin by bin minimum, the
Leq or average of each frequency over the interval period
and Leq By Time which shows the level for each frequency
from each interval record over time.
The following are examples of the interval displays:
Interval period
Time of interval
The Max display shows
the spectrum corresponding to the maximum
broadband level during
the interval period
The Min display shows
the bin by bin minimum
level for the interval
period
The Leq display shows
the average level for
each filter during the
interval period
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System 824 Views
The cursor shows
the level for the
interval record
selected
The up and down
arrow keys change
the frequency
displayed
5-13
In the Leq, Max, and Min interval displays the cursor
position (the vertical bar in the graph) corresponds to the
SPL level and frequency values on the left side of the
display. The up uand down darrow keys change the
record you are viewing.
In the Leq By Time display the upuand down darrow
keys change the frequency displayed. For each frequency the
level is shown over time for each interval period. The right
rand leftlarrow keys move you to the next and
previous interval record.
Do the following to ensure you have
Spectral Lns for the interval period:
Go to the “Edit Settings” menu for
the SSA instrument.
Interval Spectral LNs can also be selected for each interval
period. Six Ln values are shown for each frequency. Also
there are six graphical displays showing spectra for each of
the six Ln values. In order to turn on the Spectral Lns for the
interval period, go to the SSA settings menu and select
“Interval” for the Spectra Ln setting under the “Ln” menu.
To view the Interval Spectral LN displays, press the View
V key and highlight “Intervals”.
In the “Ln” menu set the following
settings to [Yes] and [Interval].
Enable Ln [Yes]
Spectral LN [Interval]
In the “Interval” menu set the
following settings to [Yes].
Intv Enable [Yes]
Press the right rarrow key to access the “Interval”
display menu and highlight “Ln Spectrum”.
Intv Save Ln’s [Yes]
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*Interval spectral LNs are only
available when the LOG option is
installed.
Press the right rarrow key to access the “Interval”
Spectral LN displays. The following menu will appear:
Highlight “Spectral” and press the check c key to view the
INTV-Ln(f) display.
Use the right rand leftlarrow keys to move to each
one-third octave frequency.
To view the Spectral 1 through Spectral 6 displays (the 6 Ln
values) use the up uand down darrow keys. Below is
an example of one of these displays:
See the section "Spectral LNs" on
page 5-20 for a detailed description
of this display.
SSA Time History
The SSA Time History display consists of six major
components:
•
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Display label
System 824 Views
5-15
•
Record number
•
SPL reading at cursor
•
Other level
•
Status
•
SPL history graph
The SLM Time History display is shown below:
5-16
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2/6/17
Display label
Record number
Time cursor
Leq reading at cursor/
Detector setting
Value of other level
Other level selected in TH
setup
SPL history graph
Status indicator
Identifies the marker
The following discusses each of these display components:
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System 824 Views
5-17
Display label - This shows the current display (in this
example, “SSA Time History”).
Leq reading at cursor - Displays the current Leq of the
time history period. This level is also shown graphically.
Time cursor/Record number - The Time cursor (the vertical
bar) allows you to scroll graphically through the history of
the displayed measurement readings using the arrow keys.
Notice that as you move back and forth in time that the
record number changes. The total number of records is also
shown.
Time history graph - Shows the history of Leq readings.
Time increases towards the right of the display.
TH represents time history which is
the TH setup in the settings menu.
Value of other level - This shows the value of the other
levels selected in the TH setup.
Use the up uand down darrow
keys to view each level selected in
the TH setup.
Other level - This shows all of the levels selected in the TH
setup in the settings menu.
Status indicator -The status indicator will show one of the
six possible events that occurred at the point of time
referenced by the time cursor:
Run - Indicates that a measurement started at this
time.
Stop - Indicates that measurement stopped at this
time.
Pause - Indicates that the measurement paused at
this time.
Cont - Indicates that the measurement continued at
this time.
Reset - Indicates that the measurement was reset at
this time.
Mark - Indicates that a marker was set at this point
in time.
Run Log
5-18
See page 6-41 for a description of the Run Log display.
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To access the Ln displays, press the View V key, use the
d key to cursor down and highlight “Ln Centiles”.
Ln Centiles
Press the right rarrow key to view the Ln displays. The
following menu will appear:
Spectral Lns are enabled by the
“Spectral Ln” setting. These data
and displays are only available when
set to “Overall”. See the section
"LOG and SSA Ln Settings"on page
7-20.
Highlight “Broadband” and press the check c key to view
the SSA-Ln-a display.
Display label
Percentile values & levels
The following is a brief description of each of the
components of this display:
•
2/6/17
Display label - The Display label identifies the display
which is the SSA-Ln-a display showing six Ln percentages for an overall measurement.
System 824 Views
5-19
Lns are reset with an Overall Reset
•
Percentile values & levels - The Ln (percentile levels)
level is that level which is exceeded ‘n’ percent of the
measurement time. By modifying the six settings, you
can select any six percentile values to be displayed at a
time.
NOTE: If Lns are enabled in the SSA
instrument, then the Back-Erase feature
is no longer available. (See the section
"Pause, Back Erase" on page 3-10 for
information on the Back-Erase feature)
Use the right rarrow key to view the SSA-Ln-b display.
Display label
Current percentage shown by cursor
Ln value as shown by cursor
Elapsed time
Ln graph
The following is a brief description of each of the
components of this display:
Use the up uand down darrow
keys to move from one percentile to
another.
•
Display label - The Display label identifies the display
which is the SSA-Ln-b display showing Ln percentages
1 through 99 graphically for an overall measurement.
•
Current percentage - Selects % of Ln to display (1 to
99), using the up uand down darrow keys to move
from one percentile to another.
•
Ln - This shows the current Ln value.
•
Elapsed time - Shows the elapsed run time accumulated
since the last overall reset.
•
Ln graph - Graph of Ln’s from 1 to 99 (1 being on the
left, 99 on the right). There are two levels represented by
each bar. The highest of the two are graphed.
Spectral LNs
To return to the Ln display menu, press the View V key. To
view the Spectral Lns highlight “Spectral” and press the
check c key to view a tabular spectral display.
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2/6/17
NOTE: Spectral Lns are measured for
SSA instrument only. If a display
bandwidth of one octave is selected with
the “bandwidth” setting these displays
will indicate “No Data Available for1/1
octave”.
This is a tabular display for each 1/3 octave frequency
showing six Ln values for the selected frequency. Below is
an example of one of the displays shown for each frequency.
Display label
Selected frequency
Percentile values & levels
The following is a brief description of each of the
components of this display:
The ‘(f)’ indicates “Ln of frequency
f”.
•
Display label - The Display label identifies the display
which is the SSA-Ln (f) display showing six Ln percent
values for the frequency displayed.
Use the right rand leftlarrow
keys to move to each 1/3 octave
frequency.
•
Selected frequency - Shows the values for the frequency
shown on the display
•
Percentile values & levels - The Ln (percentile levels)
level is that level which is exceeded ‘n’ percent of the
measurement time for the frequency band. By modifying
the six settings, you can select any six percentile values
to be displayed. The settings may be changed at any
time; spectral Ln data are only calculated while running.
To view the spectral Lns in graphical form highlight
“Spectrum 1” and press the check c key.
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System 824 Views
5-21
Use the up uand down darrow
keys to move from one spectrum Ln
display to another.
There are six displays showing all of the frequencies for
each of the six Ln values.
Below is an example of one of the “Spectrum” displays.
Display label
Ln percentage
Level at selected frequency
Selected frequency
Elapsed time
Graph of Ln at each frequency
The following is a brief description of each of the
components of this display:
Use the right rand leftlarrow
keys to change the frequency band.
5-22
•
Display label - The Display label identifies the display
which is the SSA-Ln 1(f) display showing L 1.67 for all
of the frequencies in graphical form.
•
Ln percentage - Shows Ln percentage being displayed.
•
Level at selected frequency - This shows the Ln level at
the frequency selected.
•
Selected frequency - Level shown at this frequency.
•
Elapsed time - Shows the elapsed run time accumulated
since the last overall reset.
•
Ln graph - Graph of Ln for each frequency at the percentage level displayed.
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Use an “Overall reset” to restart
overall data.
Logging SLM Specific Views
The System 824 provides a number of different displays for
the Logging SLM (LOG) instrument. Understanding these
displays allows you to take full advantage of this instrument.
All of these views can be accessed by pressing the V View
key when using the Logging SLM (LOG) instrument.
Additionally, the u or darrow keys can be used to
cycle through an associated group of views. There are three
sets of these grouped views:
The Logging SLM (LOG) views are
available when the Logging SLM is
the active setup. These views can be
accessed by pressing the V view
key.
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•
Any Data including Any Level, Any Impl, and Any
Time.
•
Current SLM, Overall SLM, Exposure, Ln Centiles,
and Stats.
•
Metrics, PassBy, and Wind / Tach.
The following briefly describes the main views available in
the Logging SLM (LOG) instrument.
Menu Items
Purpose
SLM
SLM data with graphic display of Time
History.
Any Data
Tabular display of SLM data.
Current
SLM
Maintains an accumulation of data that
may be reset immediately.
Overall
SLM
An accumulation of data over the entire
measurement period and is reset when the
entire measurement is reset.
System 824 Views
5-23
5-24
Exposure
The Exposure displays show dose and
projected dose, the sound exposure (E)
and C-A.
Ln Centiles
Display shows six selected Ln values, a
graph of L1 to L99 and a graph of the
percent greater than level.
Stats
The number of overloads and the number
of events detected.
Run Log
A listing of each run, stop, pause,
continue, and mark action with its cause,
and date/time of occurrence.
Time
History
Show the time history of Leq and
optionally many other levels such as
Lmax, Lpk or Advanced TH setup items
over short duration periods. Can also
show wind or tachometer data using
external transducers.
Intervals
Shows a full statistical history over a
longer time period by providing TWA,
SEL, Lmin, Lmax, Lpk-I, Lpk-II, and six Ln
values for each interval period. Can also
show wind or tachometer data using
external transducers.
Excd
History
A special history which is saved when the
level goes over a predetermined
threshold. Leq, SEL, Lmax, LPK-I, LPKII, duration and time history (if desired)
are saved for each exceedance record.
Can also show wind or tachometer data
using external transducers.
Daily
History
Ldn, CNEL, Leq 24, LPK-I, LPK-II, Ln’s
(if desired), Lmax and Lmin are
calculated daily; and for each hour of the
day the hourly Leq, EXCD Leq and
background Leq. Can also show wind or
tachometer data using external
transducers.
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Metrics
Measurement readings adjusted for night
and day noise impact differences.
Adjustments are based on standard
nighttime sound penalties criteria (i.e.
LDN, CNEL, etc.) The total exceedance
and background Leq metrics are also
displayed.
PassBy
Shows the largest single 10 dB passby
event detected with its Leq, SEL, Lmax,
duration, and occurrence date and time.
Wind / Tach
Shows wind or tachometer data.
Current SLM and Overall SLM Views
Current SLM clears and starts over
when the R Reset button is pressed
while running. Overall SLM does not
clear during a reset, but continues
accumulating data.
The System 824 contains two independent data buffers that
can accumulate data separately. In essence, the instrument
becomes two sound level meters in one. The data in the
primary buffer is referred to as the “overall” measurement,
while data in the secondary buffer is referred to as the
“current” measurement.
The uand darrow keys can be
used to cycle between the Current
SLM, Overall SLM, Exposure, Ln
Centiles, and Stats views.
The Current SLM and Overall SLM Views have five
common displays which can be cycled through using
therandlarrow keys. Since these displays are identical they
will be discussed together. These displays are categorized as
follows:
a) SPL
b) Times
c) Min/Max
d) Peaks
e) TWA
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System 824 Views
5-25
The different views can also be
accessed by simply selecting either
Current or Overall SLM with the c
Check key from within the main View
menu then cycling through the views
with therandlarrow keys.
These displays can be accessed directly from the View menu
screen by doing the following:
Step 1
Press the V View key to enter the View menu.
Step 2
Highlight either Current SLM or Overall SLM.
Press the rarrow key and one of the following
screen appears:
Step 3
Use the uand darrow keys to highlight the
desired view.
The land rarrow keys allow
you to move through the view’s
available displays.
Step 4
Press the c Check key or therarrow key to
enter the selected view.
Current SLM/Overall SLM
Display-a (SPL)
The Current/Overall-a SLM (or SPL) display consists of six
major components:
5-26
•
Display label
•
Current SPL reading and weight setting
•
Selected detector
•
Elapsed time
•
Status
•
SPL history graph
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The Current SLM-a or SPL display is shown below:
Display label
Status
Current SPL reading
and weight setting
SPL history graph
Detector setting
Elapsed time
The following discusses each of these display components:
Display label - This shows the current display (in this
example, “SLM Current-a”). The display represents both
Current-a and Overall-a display.
Current reading and weight setting - Displays the current
SPL reading. This level is also shown graphically by the bar
on the far right of the SPL history graph. The frequency
weighting for SPL can be either A, C, or FLAT.
Detector setting - The current detector is indicated (for
example, Slow SPL) and can be Slow, Fast, or Impl.
Elapsed time - This displays the length of time the current
measurement has been running. It will reset to zero when the
R Reset key is pressed (Current SLM only). It will also
pause when the p Pause key is pressed and then continue
when it is pressed again. The timer is displayed as mm:ss.ss,
hh:mm:ss or hhhhh:mm.
SPL history graph - Shows a recent history of one second
Leq readings. The far right bar displays the current SPL
reading. As readings are taken, they are placed onto the
scrolling graph from right to left once per second.
Current/Overall SLM Display-b
(Times)
The Current / Overall-b SLM or Times display consists of
four major components:
•
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Display label
System 824 Views
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•
Start date / time
•
Elapsed time
•
End date / time
The SLM Current-b or Times display is shown below:
Display label
Start date/time
End date / time
Elapsed time
The following explains each of the display’s components:
Display label - This shows the current display (for example,
“SLM Current-b”). The display represents both Current-b
and Overall-b display.
Start date/time - Date and time the current/overall
measurement began.
Elapsed time - The Elapsed Time displays the length of
time the current or overall measurements have been running.
It will restart at zero when the R Reset key is pressed
(Current SLM only). It will also pause when the p Pause
key is pressed and then continue when it is pressed again.
The timer is displayed as hhhhh:mm:ss.s
End date/time - Date and time the current/overall
measurement ended (or current time if still running).
Current/Overall SLM Display-c
(Min/Max)
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The Current/Overall-c SLM or Min/Max display consists of
three major components:
•
Display label
•
Current/Overall Lmax reading
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•
Current/Overall Lmin reading
The SLM Current-c or Min/Max display is shown below:
Display label
Current/Overall
Lmax reading
Current/Overall
Lmin reading
The following explains each of the display’s components:
Display label - This shows the current display (for example,
“SLM Current-c”). The display represents both Current and
Overall-c display.
Current / Overall Lmax reading - Displays Lmax or
maximum level that occurred, and the date and time when it
occurred.
Current / Overall Lmin reading - Displays Lmin or
minimum level that occurred, and the date and time when it
occurred.
Current/Overall SLM Display-d
(Peaks)
The Current / Overall-d SLM or Peaks Display consists of
three major components:
•
Display label
•
Current / Overall Flat Weighted Peak
•
Current / Overall C - Weighted Peak
•
Current / Overall A - Weighted Peak
The SLM Current -d or Peaks display is shown below:
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Display label
Flat Weighted Peak
C - Weighted Peak
A - Weighted Peak
The following information explains each of the display’s
components:
Display label - Shows the display currently being used (for
example, “SLM Current-d”). The display represents both
Current-d and Overall-d display.
Current/Overall Flat Weighted Peak reading - Shows the
flat weighted value from the System 824’s peak detector
along with the date and time that the peak event occurred.
Current/Overall C - Weighted Peak reading - Shows the
C weighted value from the System 824’s peak detector along
with the date and time that the peak event occurred.
Current/Overall A - Weighted Peak reading - Shows the
A weighted value from the System 824’s peak detector along
with the date and time that the peak event occurred.
Current/Overall SLM Display-e
(TWA)
The Current/Overall-e SLM display consists of four major
components:
•
Display label
•
TWA indicator and level
•
Sound exposure level
•
Elapsed time
The SLM Current -e or TWA display is shown below:
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Display label
TWA indicator and level
Sound exposure level
Elapsed time
The following explains each of the display’s components:
Display label - This shows the current display (for example,
“SLM Current-e”). The display represents both Current and
Overall -e display.
TWA indicator and level - The indicator is based on the
exchange rate (Leq for 3dB exchange rate and threshold = 0.
TWA for all others) and the Time Weighted Average level.
Sound exposure level - The Sound Exposure Level (SEL) is
measured in dB. This is the TWA normalized to one second.
Elapsed time - This shows the elapsed run time
accumulated since the last current/overall reset. This is the
time over which the current TWA is averaged.
Exposure Views
The uand darrow keys can be
used to cycle between the Current
SLM, Overall SLM, Exposure, Ln
Centiles, and Stats views.
The Exposure View has three displays which can be
accessed by simply selecting Exposure with the c Check
key from within the main View menu then cycling through
the views with the randlarrow keys until the desired
display appears.
Exposure Display-a
The Exposure-a
components:
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•
Display label
•
Dose
System 824 Views
display
consists
of
seven
major
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•
Projected dose
•
Time Weighted Average
•
Sound Exposure Level
•
Elapsed Time
The Exposure-a display is shown below:
Display label
Dose
Projected Dose
Time weighted average
Sound exposure level
Elapsed Time
The following explains each of the display components:
Display label - This shows the current display (for example,
“SLM Exposure-a”).
Dose - By definition, a person receives 100% dose when
exposed to a noise having a TWA equal to the selected
criterion level for a time equal to the criterion time (usually
eight hours). This corresponds to the maximum safe noise
exposure. Exposures at higher levels will result in a 100%
dose in less time; or if exposure continues, the exposure will
exceed 100% dose.
Projected dose - Projected dose is the dose that will occur if
current noise levels continue for the entire criterion time.
Time weighted average - This display shows the Time
Weighted Average (TWA) measured in dB.
Sound exposure level - This display shows the Sound
Exposure Level (SEL) measured in dB.
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Elapsed time - The timer display shows the elapsed run
time accumulated since the last overall reset. This is the time
over which the overall TWA is averaged.
Exposure-b Display
The Exposure-b display consists of five major components:
•
Display label
•
Sound exposure
•
Sound exposure level
•
Time weighted average
•
Elapsed Time
The Exposure -b display is shown below:
Display label
Sound exposure
Sound exposure level
Time weighted average
Elasped Time
The following explains each of the display components:
Display label - Shows the current display (for example,
“SLM Exposure-b”).
Takt3 and Takt5 are available
options if Takt functionality has been
enabled. (See the Menu Item "About"
on page 3-18).
Sound exposure - Sound Exposure (E) in Pascal squared
hours (Pa2H). The Sound Exposure (E) is a function of the
Leq and the elapsed time of the overall measurement.
Time weight average - This display shows the Time
Weighted Average (TWA) measured in dB.
Sound exposure level - Shows the Sound Exposure Level
(SEL) measured in dB.
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Elapsed time - Shows the elapsed run time accumulated
since the last overall reset. This is the time over which the
overall TWA is averaged.
If Takt functionality has been enabled, the Exposure-b
display will look as shown below:
Display Label
Sound Exposure
Takt3
Takt5
Timer
Exposure-c Display
The Exposure-c display consists of four major components:
•
Display label
•
C - Weighted TWA
•
A - Weighted TWA
•
C minus A TWA
The Exposure-c display is shown below:
Display label
C - Weighted TWA
A - Weighted TWA
C-A Weighted TWA
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The following explains each of the displays:
Display label - Shows the current display (for example,
“SLM Exposure-c”).
C-Weighted TWA - This display shows the C weighted
TWA (Leq) over the duration of the measurement.
A-Weighted TWA -This display shows the A weighted
TWA (Leq) over the duration of the measurement.
This measurement is commonly used
for assessing the effectiveness of
hearing protection.
C minus A Weighted TWA - This display shows the C
weighted TWA (Leq) minus the A weighted TWA (Leq) over
the duration of the measurement.
Ln Centiles Views
The uand darrow keys can be
used to cycle between the Current
SLM, Overall SLM, Exposure, Ln
Centiles, and Stats views from the
Ln-a display.
The Ln Centiles View has two displays which can be
accessed by simply selecting Ln Centiles with the c Check
key from within the main View menu then cycling through
the views with the randlarrow keys until the desired
display appears.
Ln-a Display
The Ln-a display consists of two major components:
•
Display label
•
Percentile values & levels
The Ln Centiles-a display is shown below for the LOG
instrument:
Display label
Percentile values & levels
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The following explains each of the display components:
Display label - Shows the current display (for example,
“Ln-a”).
Percentage settings are entered with
a 1/100th dB resolution, but are
displayed to the nearest 1/10th dB
when 10 dB or greater.
Percentile values & levels - The Ln (percentile levels) level
is that level which is exceeded ‘n’ percent of the
measurement time. By modifying the six settings you can
select any six percentile values to be displayed at a time. For
example, if you set one of these settings to 10.5, then L10.5
would be one of the six percentiles that is displayed. The
value of L10.5 is the level that has been exceeded 10.5% of
the time during the overall measurement.
Ln-b Display
The Ln-b display consists of five major components:
•
Display label
•
Current % record
•
Ln
•
Elapsed Time
•
Ln graph
The Ln Centiles-b display is shown below for the LOG
instrument:
Display label
Current%
Ln
Ln graph
Elapsed Time
The following explains each of the display’s components:
Display label - Shows the current display (for example,
“Ln-b Centiles”).
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Current% - Selects percentage of Ln to display (1 to 99),
using the u and d arrow keys to move from one
percentile to another.
Ln - This display shows the current Ln value.
Elapsed time - Shows the elapsed run time accumulated
since the last current reset.
Ln graph- Graph of Ln’s from 1 to 99 (1 being on the left,
99 on the right).
NOTE: There are two Lns per bar in the
graph. The higher of the two is graphed.
Stats Views
The Stats View has three displays which can be accessed by
simply selecting Stats with the c Check key from within
the main View menu then cycling through the views with the
randlarrow keys until the desired display appears.
Stats-a Display
The uand darrow keys cycle
between the Current SLM, Overall
SLM, Exposure, Ln Centiles, and
Stats views.
The Stats-a display consists of three major components:
•
Display label
•
Trigger level 1 and event counter
•
Trigger level 2 and event counter
The Stats-a display is shown below:
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System 824 Views
5-37
Display label
Trigger level 1
and event counter
Trigger level 2
and event counter
The following explains each of the display components:
Display label - This shows the current display (for example,
“SLM Stats-a”).
Trigger level 1 and event counter - This presents a
summary of the number of times during the overall
measurement that the SPL exceeded the pre-programmed
trigger level 1. In this example, trigger level 1 is set to
115 dBA and the SPL exceeded this threshold 0 times. These
may be considered as individual events.
Trigger level 2 and event counter - Summary of the
number of times during the overall measurement that the
SPL exceeded the pre-programmed trigger level 2. In this
example, trigger level 1 is set to 120 dBA and the SPL
exceeded this threshold 0 times. These may be considered as
individual events.
Stats-b Display
The Stats-b display consists of three major components:
•
Display label
•
Peak-I trigger
•
Peak-II trigger
The Stats-b display is shown below:
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Display label
Peak-I trigger
Peak-II Trigger
The following explains each of the display’s components:
Display label - This shows the current display (for example,
“SLM Stats-b”).
Peak-I trigger - This presents a summary of the number of
times during the overall measurement that the Peak-I level
exceeded its pre-programmed trigger level. In this example,
Peak-I’s trigger level is set to 140dBF and the Peak-I level
exceeded this threshold 0 times. These may be considered as
individual events.
Peak-II trigger - This presents a summary of the number of
times during the overall measurement that the Peak-II level
exceeded its pre-programmed trigger level. In this example,
Peak-II’s trigger level is set to 140dBA and the Peak-II level
exceeded this threshold 0 times. These may be considered as
individual events.
Stats-c Display
The Stats-c display consists of two major components:
•
Display label
•
Overload message
The Stats-c display is shown below:
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5-39
Display label
Overload message
The following explains the display components:
Display label - This shows the current display (for example,
“SLM Stats-c”).
Overload message - The “Stats-c” display indicates the
occurrence of instrument overloads during the measurement.
If one or more overloads have occurred, the display shows
the total number of overloads. If no overloads have
occurred, the display shows a “No Overloads have
occurred” message instead.
Run Log (LOG & SSA)
The Run Log displays the start and stop times/dates of the
active measurement in the System 824’s memory. You use
the uanddarrow keys to scroll through the log records.
The “Run Log” display can be accessed by simply selecting
Run Log with the c Check key from within the main View
menu.
The Run Log display consists of four major components:
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•
Display label
•
Log number
•
Event Date / Time
•
Run / Stop indicator
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The Run Log display is shown below for the LOG and SSA
instruments:
Display label
Previous action
Previous record
Log Number
Run/Stop Indicator
Event Date/Time
Current record
Number of time
history samples for
this run/stop period
Next record
The following explains this display components:
Display label - Shows the display currently being used (for
example, “Run Log”).
Log Number- The “Run Log” display shows the start and
stop times/dates of measurements in active memory. Each
measurement is logged in memory in the order that it
occurred. The Log Number indicates the order of the
displayed log entry in relation to the other log entries
currently in active memory.
Event Date/Time - The Event Date/Time shows the time
and date that this Log entry either started to run or was
stopped.
Run/Stop Indicator- Each measurement reading log has
two entries; one corresponding to when the measurement
started to run and the other entry corresponding to when the
measurement was stopped. The Run/Stop indicator shows
whether the log entry indicates the time and date of a Run
log entry or a Stop log entry.
Time History
With the Time History View you can graphically scroll
through and view the SPL readings at different points of
time in the measurement readings currently active in
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System 824 Views
5-41
memory. You can access the Time History display by
selecting Time History with the c Check key from within
the main View menu.
Example Time History displays are shown below:
Display Label
Status Indicator
Time Cursor
Other level
Marker set at this point in the time history
ddfadf
Idddddddd
Identifies the Marker
The following explains the display components:
Display label - This shows the current display (for example,
“SLM Time History”).
Status Indicator- The Status Indicator will show one of the
three possible events that occurred in the point of time
referenced by the Time Cursor:
Run - Indicates a measurement started at this time.
Stop - Indicates a measurement stopped at this
time.
Pause - Indicates the measurement paused at this
time.
Cont - Indicates the measurement continued at
this time.
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Mark - Indicates a marker was set at this point in
time.
Time Cursor- The Time Cursor (the vertical bar) allows
you to scroll graphically through the history of the displayed
measurement readings using the landrarrow keys.
The Time History Status Indicator will show what event
took place at the point in time associated with the Time
Cursor’s current position.
See the section O
" ther Level - (LOG
only)" on page 7-33 for additional
details.
Other level - A wide range of different parameters can be
displayed in this window depending upon the setup
procedure utilized.
Single Other Level
The simplest situation is when the user selects to display a
single alternative sound level parameter, Pk-II, Pk-I or
Lmax, which is setup directly using the Other Level menu in
the Time History menu. In this case, the value of this
particular parameter will always appear in the same position
as shown by the Lmax display in the figure above.
Multiple Other Levels
Alternatively, the user could select from as many as forty
different parameters, which could include sound pressure
levels with different weightings (A, C, or F) and different
averaging times (S, F, I), RTA Spectra and even some nonacoustic parameters such as Wind/Tach data, Temperature
(824 interior), External Voltage and Battery Voltage. Setting
up for multiple other levels requires the use of the Advnc TH
menu in the Time History menu. The selected parameters
will be displayed in the same position as Lmax in the figure
above. Use the uand darrow keys to scroll through the
other selected parameters. The following shows how six
different values of “other parameter” can be displayed on
one particular Time History View by using these arrow keys.
The graphics on the second row indicate Windspeed, Wind
Direction and Temperature (measured using a temperature
transducer inside the System 824).
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ddfadf
Idddddddd
Intervals
The uand darrow keys show
different intervals in history. The
l and rarrow keys cycle you
through the different Interval
screens.
The Intervals view shows a record of various sound pressure
data gathered in time segments over a set period of time. An
example would be a measurement where data is gathered in
one hour time intervals over a 24 hour period. You can
access the Intervals view display by selecting Intervals with
the c Check key from within the main View menu.
Intervals-a Display
The Interval-a display consists of six major components:
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•
Display label
•
Interval Number
•
Interval Date / Time
•
Leq Reading
•
SEL Reading
•
Interval Duration
824 Reference Manual
2/6/17
The Interval-a display is shown below for the LOG and
SSA instruments:
Display label
Interval Number
Interval Date/Time
Leq Reading
SEL Reading
Interval Duration
The following explains each of the display components:
Display label - This shows the current display (for example,
“Interval-a”).
Interval Number- The Interval display shows each
measurement interval in the order that it occurred. The
Interval Number indicates the order of the displayed interval
in relation to the other interval records.
Interval Date / Time - The Event Date/Time shows the time
and date that this interval began.
Leq Reading - The Leq Reading shows the Leq for the
currently displayed interval.
SEL Reading - The SEL Reading shows the SEL for the
currently displayed interval.
Interval Duration - The Interval Duration shows the length
of time of the currently displayed interval.
Intervals-b Display
2/6/17
The Interval-b display consists of six major components:
•
Display label
•
Interval Number
•
Interval Date / Time
System 824 Views
5-45
•
Lmax Reading
•
Lmin Reading
•
Interval Duration
The Interval-b display is shown below for the LOG and
SSA instruments:
Display label
Interval Number
Interval Date/Time
Lmax Reading
Lmin Reading
Interval Duration
The following explains each of the display components:
Display label - This shows the current display (for example,
“Interval-b”).
Interval Number- The “Interval” displays each
measurement interval in the order that they occurred. The
Interval Number indicates the order of the displayed interval
in relation to the other interval records.
Interval Date/Time - The Event Date/Time shows the time
and date that this interval began.
Lmin Reading - The Lmin Reading shows the Lmin for the
currently displayed interval.
Lmax Reading - The Lmax Reading shows the Lmax for
the currently displayed interval.
Interval Duration - The Interval Duration shows the length
of time of the currently displayed interval.
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Intervals-c Display
The Interval-c display consists of six major components:
•
Display label
•
Interval Number
•
Interval Date / Time
•
Lpeak - I Reading
•
Lpeak - II Reading
•
Interval Duration
The Interval-c display is shown below for the LOG and SSA
instruments:
Display label
Interval Number
Interval Date/Time
Lpeak - I Reading
Lpeak - II Reading
Interval Duration
The following explains each of the display components:
Display label - This shows the current display (for example,
“Interval -c”).
Interval Number- The Interval Number display shows each
measurement interval in the order that it occurred. The
Interval Number indicates the order of the displayed interval
in relation to the other interval records.
Interval Date/Time - The Event Date/Time shows the time
and date that this interval began.
Lpeak - I Reading - The Lpeak - I Reading shows the
Lpeak - I reading for the currently displayed interval.
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Lpeak- II Reading - The Lpeak - II Reading shows the
LPeak - II reading for the currently displayed interval.
Interval Duration - The Interval Duration shows the length
of time of the currently displayed interval.
Intervals-d Display
The Interval-d display consists of six major components:
•
Display label
•
Interval Number
•
SPL Exceedances
•
Peak - I Exceedances
•
Peak - II Exceedances
•
Overloads
The Interval-d display is shown below for the LOG and
SSA instruments:
Display label
SPL Exceedances
Peak-I Exceedances
Peak-II Exceedances
Overloads
Interval Number
The following explains each of the display’s components:
Display label - This shows the current display (for example,
“Interval-d”).
Interval Number- The Interval Number display shows each
measurement interval in the order that it occurred. The
Interval Number indicates the order of the displayed interval
in relation to the other interval records.
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SPL Exceedances - SPL Exceedances shows how many
times during this interval that the instrument’s SPL
Exceedance Level was surpassed.
Peak-I Exceedances - Peak-I Exceedances shows how
many times during this interval that the instrument’s Peak - I
Exceedance Level was surpassed.
Peak-II Exceedances - Peak-II Exceedances shows how
many times during this interval that the instrument’s Peak-II
Exceedance Level was surpassed.
Overloads - This shows how many overloads occurred
during this interval.
Intervals-e Display
The Interval-e display consists of three major components:
•
Display label
•
Interval Number
•
Ln Centiles Readings
The Interval-e display is shown below (LOG instrument
only):
Display label
Interval Number
Ln Centiles
Readings
The following explains each of the display’s components:
Display label - This shows the current display (for example,
“Interval-e”).
Interval Number - The “Interval Number” display shows
each measurement interval in the order that it occurred. The
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System 824 Views
5-49
Interval Number indicates the order of the displayed interval
in relation to the other interval records.
Ln Centiles Readings - Shows the six Ln Centiles readings
for this interval.
Intervals-f Display
The Interval-f display consists of seven major components:
•
Display label
•
Interval Number
•
Interval Date/Time
•
Average Windspeed
•
Maximum Windspeed
•
Direction of Maximum Windspeed
•
Interval Duration
The Interval-f display is shown below (LOG instrument only)
:
Display label
Interval Number
Interval Date/Time
Average Wind Speed
Maximum Wind Speed
and Direction
Interval Duration
The following explains each of the display’s components:
Display label - This shows the current display (for example,
“Interval-f Wind”).
Interval Number - The “Interval Number” display shows
each measurement interval in the order that it occurred. The
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Interval Number indicates the order of the displayed interval
in relation to the other interval records.
This display will show
Interval Date/Time - The Interval Date/Time shows the
date and time that this interval began.
Average Windspeed - The Average Windspeed is the
numerical average of the windspeed over the duration of this
interval.
if the interval setting “Intv Save
Ln’s” is set to “No”.
Maximum Windspeed - The Maximum Windspeed is the
maximum instantaneous value of windspeed logged during
this interval.
Direction of Maximum Windspeed - The Direction of
Maximum Windspeed is the direction of the maximum
instantaneous value of windspeed logged during this
interval.
Interval Duration - The Interval Duration shows the length
of time of the currently displayed interval.
Exceedance History
Event recording begins when any one of the three following
conditions is satisfied:
•
The instantaneous sound pressure level, Lp, exceeds the
value of SPL Exceedance Level 1 set by the user.
•
The instantaneous peak level Pk-1, exceeds the value of
Pk-1 Exceedance Level set by the user.
•
The instantaneous peak level Pk-2, exceeds the value of
Pk-2 Exceedance Level set by the user.
Event recording ends when all three of these levels, Lp, Pk-1
and Pk-2, are below their respective exceedance levels
minus the Hysteresis level setting. The exceedance will only
be saved if its duration is longer than the minimum duration
setting.
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For further information, see sections
"LOG and SSA Triggering Settings"
on page 7-22 and "Logging SLM
Exceedance History Settings" on
page 7-39. The System 824 Training
Manual, available from Larson
Davis, is also an excellent reference.
The Exceedance view shows a record of each exceedance
recorded when the sound pressure level went over a
predetermined threshold. You can access the Excd History
view display by selecting Excd History with the c Check
key from within the main View menu.
Excd-a Display
The Excd-a display consists of six major components:
•
Display Label
•
Exceedance Number
•
Exceedance Date / Time
•
Leq Reading
•
SEL Reading
•
Exceedance Duration
The Excd-a display is shown below:
Display label
Excd Number
Exceedance Date/Time
Leq Reading
SEL Reading
Exceedance Duration
The following explains each of the display components:
Display label - This shows the current display (for example,
“Excd-a”)
Exceedance Number - The “Exceedance” display shows
each exceedance record in the order that it occurred. The
exceedance number indicates the order of the displayed
exceedance in relation to the other exceedance records.
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Exceedance Date/Time - The Event Date/Time shows the
time and date that this exceedance occurred.
Leq Reading - The Leq Reading shows the Leq for the
currently displayed exceedance.
SEL Reading - The SEL Reading shows the SEL for the
currently displayed exceedance.
Exceedance Duration - The Exceedance Duration shows
the length of time this exceedance lasted.
Excd-b Display
The Excd-b display consists of six major components:
•
Display label
•
Exceedance Number
•
Exceedance Date / Time
•
Peak - I Reading
•
Peak - II Reading
•
Max Reading
The Excd-b display is shown below:
Display label
Excd Number
Exceedance Date/Time
Peak-I Reading
Peak-II Reading
Maximum level during excd
The following explains each of the display components:
Display label - This shows the current display (for example,
“Excd-b”)
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Exceedance Number - The “Exceedance” display shows
each exceedance record in the order that it occurred. The
exceedance number indicates the order of the displayed
exceedance in relation to the other exceedance records.
Exceedance Date/Time - The Event Date/Time shows the
time and date that this exceedance occurred.
Peak-I Reading - The Peak-I Reading shows the Peak-I
level recorded during this exceedance.
Peak-II Reading - The Peak-II Reading shows the Peak-II
level recorded during this exceedance.
Maximum Reading - The Max Reading shows the
maximum level recorded during this exceedance.
Excd-c Display
The Excd-c display consists of six major components:
•
Display label
•
Exceedance Number
•
Exceedance Date / Time
•
Maximum Windspeed
•
Direction of Maximum Windspeed
•
Maximum Reading
Display label
Excd Number
Exceedance Date/Time
Maximum Windspeed
and Direction
Maximum level during excd
The following explains each of the display components:
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Display label - This shows the current display (for example,
“Excd-c Wind”)
Exceedance Number - The “Exceedance” display shows
each exceedance record in the order that it occurred. The
exceedance number indicates the order of the displayed
exceedance in relation to the other exceedance records.
Exceedance Date/Time - The Event Date/Time shows the
time and date that this exceedance occurred.
Maximum Windspeed - The Maximum Windspeed is the
highest instantaneous windspeed logged during this
exceedance event.
Direction of Maximum Windspeed - The Direction of
Maximum Windspeed is the direction of the maximum
instantaneous value of windspeed logged during this
exceedance event.
Maximum Reading - The Max Reading shows the
maximum level recorded during this exceedance.
Excd Time History Display
You have the option of recording a time history for each
exceedance by setting “Excd Time-Hist” to “Yes” under the
“Excd History” settings via the SETUP S key. An
exceedance time history will be recorded for every
exceedance record.
An exceedance time history will only be recorded when all
of the criteria have been met such as:
•
SPL Exceedance Level I
•
Minimum Duration
While displaying any of the Exceedance Displays (a, b or c),
the corresponding Exceedance Time History can be
displayed by pressing the c key twice. A subsequent
double click of the c key will return the display to the
corresponding Exceedance Display.
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NOTE: For a detailed description of
Exceedance Time History settings, see
the section L
" ogging SLM Exceedance
History Settings"on page 7-39.
The Excd Time History display consists of seven major
components:
•
Display Label
•
Current Record
•
Level at cursor
•
Time at cursor
•
Current sample
•
Total number of samples
•
Total number of Excd records
•
Graph of Exceedance Time History
The Excd Time History display is shown below:
Total number of
Excd records
Display label
Current record
Level at cursor
Graph of Excd
time history
Time at cursor
Current sample
Total number of samples
The following explains each of the display components:
Display Label - This shows the current display (for
example, “Excd-TH”)
Current Record - The “Excd-TH” display shows each
exceedance record in the order that it occurred. This number
shows that you are viewing the time history corresponding
to this particular exceedance record. Use the
dandukeys to move forward or backwards,
respectively, through the sequence of Exceedance History
records. Alternately, you can press the c key, highlight
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Locate, and press the c key again. This will open a window
permitting you to jump to the first or last Exceedance or to a
selected exceedance record.
Level at Cursor - Shows the level in dB at the point in time
indicated by the cursor. Use the randlkeys to position
the cursor along the time axis.
Time at Cursor - Shows the time in seconds of the sample
indicated by the cursor.
Current Sample - This is the current sample number as
indicated by the cursor.
Total Number of Samples -Shows the total number of
samples taken for this exceedance.
Total Number of Excd Records - Shows the total number
of exceedances recorded.
The exceedance time history
includes 10 samples preceding the
event and 10 samples after the event.
The maximum number of samples
that can be stored are 128. In this
case only the first 128 samples are
stored including the 10 pre-event
samples.
Graph of Exceedance Time History - Shows graphically
all of the samples taken for the time history. These values
follow the instantaneous sound envelope determined by
short period Leq samples. As a result, it does not exhibit the
relatively slow decay characteristics associated with Slow or
Fast detectors.
Daily Views
The Daily history logs daily sound statistics including Leq
24, LDN, CNEL, Ln’s, Max, Min, and Peak data. The
measurement period is from 12:00 midnight to 12:00
midnight each day. For each hour it logs Leq, Background
Leq and the hourly Excd Leq. You can access the Daily
display by selecting Daily with the c Check key from
within the main View menu, then cycling through the views
with the randlarrow keys until the desired display
appears. The hourly data is accessed by pressing the c
Check key while in the Daily-a or Daily-b displays.
Daily-a Display
The Daily-a display consists of 11 major components:
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•
Display label
•
Record Number
•
Elapsed Time
•
Date
•
Leq Reading
•
LDN and CNEL Readings
•
Maximum and Minimum levels
•
Peak level
The Daily-a display is shown below:
Display label
Elapsed time
Date
Leq Reading
LDN and CNEL Readings
Max and Min levels
Peak levels
Record Number
(A new record is
created each
new day)
The following explains each of the display components:
Display label - This shows the current display (for example,
“Daily-a”).
If the 824 is started at 1900 hours,
the first Daily record will run from
1900 hours to 0000 hours and then a
new day (Daily record) will begin.
Record Number - Each “Daily” record is shown in the
order that it occurred. The record number indicates the order
of the displayed Daily record in relation to the other records.
A new daily record is created each new day. A day is defined
as 12:00 midnight to 12:00 midnight.
Elasped Time - This shows the elapsed time of this day’s
measurement.
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Date - This shows the day, date, month and year for this
record.
Leq Reading - This shows the Leq for the day.
LDN Reading - The DNL (Day-Night Average Sound
Level) display shows the equivalent sound level for a 24hour period with a +10dB weighting applied to all sounds
occurring between the times 22:00 and 07:00.
CNEL Reading - The CNEL (Community Noise Equivalent
Level) display shows the equivalent sound level for a 24hour period with a +5dB weighting applied to all sounds
occurring between the times 19:00 and 22:00 and a +10dB
weighting applied to all sounds occurring between the times
22:00 and 07:00.
Maximum and Minimum levels - This shows the
maximum and minimum levels during this day’s
measurements.
Peak level - This shows the peak level during the day with
different weighting applied.
Daily-b Display
The Daily-b display consists of 4 major components:
•
Display label
•
Record Number
•
Date
•
Ln Percentiles
The Daily-b display is shown below:
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Display label
Record Number
Date
Ln Percentiles
The following explains each of the display’s components:
Display label -This shows the current display (for example,
“Daily-b”).
Record Number - Each “Daily” record is shown in the
order that it occurred. The record number indicates the order
of the displayed Daily record in relation to the other records.
A new daily record is created each new day. A day is defined
as 12:00 midnight to 12:00 midnight.
Date - Day, Date, month and year of the record
Ln Percentiles - The Ln (percentile levels) level is that level
which is exceeded ‘n’ percent of the measurement time. You
can select any six percentile values to be calculated and
stored with the daily record.
Daily-c Wind Display
The Daily-c Wind display consists of 10 major components:
If the optional firmware 824-WND is
not installed, the following message
will appear
•
Display label
•
Record Number
•
Date
•
Duration
•
Average Windspeed
•
Maximum Windspeed
•
Direction of Maximum Windspeed
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•
Time of Maximum Windspeed
•
Wind Exceedance Data
•
Windy Threshold Data
Display label
Date
Record Number
Average Windspeed
Maximum Windspeed
Duration
Direction of
Max Windspeed
Windy Exceedance Data
Windy Threshold Data
Time of Maximum Windspeed
The following explains each of the display components:
Display label -This shows the current display (for example,
“Daily-c Wind”).
Record Number - Each “Daily” record is shown in the
order that it occurred. The record number indicates the order
of the displayed Daily record in relation to the other records.
A new daily record is created each new day. A day is defined
as 12:00 midnight to 12:00 midnight.
Duration - The Duration shows the length of time
represented by this Daily View (measurement may have
been stopped before the complete 24 hour period).
Average Windspeed - The Average Windspeed is the
numerical average of the windspeed over the duration of this
record.
Maximum Windspeed - The Maximum Windspeed is the
highest instantaneous windspeed logged during this record.
Direction of Maximum Windspeed - The Direction of
Maximum Windspeed is the direction of the maximum
instantaneous value of windspeed logged during this record.
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Time of Maximum Windspeed - The Time of Maximum
Windspeed is the time (hh:mm:ss) when the maximum
windspeed occurred.
Wind Exceedance Data - The Wind Exceedance Data
includes the value of the Wind Exceedance Level (in this
instance 40.11) and the number of times the windspeed
exceeded this level.
Windy Threshold Data - The Windy Threshold Data
includes the value of the Windy Threshold Level (in this
instance 5.04) and the percent of the time that the windspeed
was above this level.
Daily-d Windy Percent Display
The Daily-d Windy Percent display consists of 4 major
components:
•
Display label
•
Record Number
•
Date
•
Percent Windy Condition
•
Windy Directional Distribution
Display label
Date
Windy Directional
Distribution
Duration
% Windy
The following explains each of the display components:
Display label -This shows the current display (for example,
“Daily-d Wind”).
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Record Number - Each “Daily” record is shown in the
order that it occurred. The record number indicates the order
of the displayed Daily record in relation to the other records.
A new daily record is created each new day. A day is defined
as 12:00 midnight to 12:00 midnight.
Percent Windy Condition - The Percent Windy Condition
is the percent of the time the windspeed was above the
Windy Threshold Level.
Windy Directional Distribution - The Windy Directional
Distribution is shown on a compass rose with indications of
the percent of the time that windspeed is above the Windy
Threshold Level were in the directions covered by each of
the eight directional coordinates. For example, in this
instance winds having levels above the Windy Threshold
Level of 5.04 (shown on the Daily-c View) were from the
North West 68% of the time.
Hourly Leq Display
The Hourly Leq display consists of 7 major components:
•
Display label
•
Date
•
Record Number
•
Hourly Leq reading
•
Exceedance Leq
•
Background Leq
•
Partial hour indicator
•
Hourly Leq graph
The Hourly Leq display is shown below:
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Date
Record Number
Display label
Hourly Leq Reading
Exceedance Leq
Background Leq
Hour indicator
Hourly Leq
graph
The following explains each of the display components:
Display label - This shows the current display (for example,
“Hourly Leq”).
Date - Date of the record
Record Number - The record number indicates the order of
the displayed Daily record in relation to the other records.
Hourly Leq Reading - This is the hourly Leq as shown by
the cursor.
Exceedance Leq - This shows the average level of all of the
exceedance events.
Background Leq - The background Leq is the hourly Leq
minus the exceedance Leq.
Hour indicator - The hour indicator shows which hour of the
day is being displayed. A “p” following the Hour indicator
means that the measurement was not for a full hour.
Hourly Leq graph - This graph shows the Leq value for each
hour. Use the randlarrow keys to move the cursor to
view the Leq, background Leq and exceedance Leq for each
hour.
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Metrics
The uand darrow keys can be
used to cycle between the Metrics,
PassBy, and Wind / Tach views.
The Metrics View has two displays which can be accessed
by simply selecting Metrics with the c Check key from
within the main View menu then cycling through the views
with the randlarrow keys until the desired display
appears.
Metrics-a Display
The Metrics-a display consists of five major components:
•
Display label
•
Leq Reading
•
DNL Reading
•
CNEL Reading
•
Elapsed Time
The Metrics-a display is shown below:
Display label
Elapsed Time
Leq Reading
DNL Reading
CNEL Reading
The following explains each of the display’s components:
Display label - This shows the current display (for example,
“Metrics-a”).
Leq Reading- This display shows the average level over the
elapsed time.
DNL Reading - The DNL (Day-Night Average Sound
Level) display shows the equivalent sound level for the
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entire measurement period with a +10dB weighting applied
to all sounds occurring between the times 22:00 and 07:00.
CNEL Reading - The CNEL (Community Noise Equivalent
Level) display shows the equivalent sound level for the
entire period with a +5dB weighting applied to all sounds
occurring between the times 19:00 and 22:00 and a +10dB
weighting applied to all sounds occurring between the times
22:00 and 07:00.
Elapsed Time- This shows the elapsed time of the overall
measurement.
Metrics-b Display
The Metrics-b display consists of six major components:
•
Display label
•
Leq Reading
•
Leq Exceedance
•
Leq Background
•
Elapsed Time
The Metric -b display is shown below:
Display label
Elapsed Time
Leq Reading
Leq Exceedance
Leq Background
The following explains each of the display components:
Display label - This shows the current display (for example,
“Metrics-b”).
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Leq Reading - This shows the level of a constant sound over
a specific time period that has the same sound energy as the
(unsteady) sound over the same period.
Exceedance Leq - This displays the average Leq of all the
exceedance events.
Exceedance Duration - Total time of all exceedances.
Background Leq - This display shows the average Leq for
the total measurement period minus the combined event Leq.
Elapsed Time - This shows the elapsed time of the overall
measurement.
PassBy
The uand darrow keys can be
used to cycle between the Metrics,
PassBy, and Wind / Tach views.
The PassBy View has a single display that shows the largest
single 10dB passby event detected. The display can be
accessed by simply selecting PassBy with the c Check key
from within the main View menu.
The PassBy display consists of six major components:
•
Display label
•
Leq Reading
•
SEL Reading
•
Max Reading
•
Date/Time
•
Elapsed Time
The PassBy display is shown below:
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Display label
Date/Time
Elapsed Time
Leq Reading
SEL Reading
Max Reading
The following explains each of the display’s components:
Display label - This shows the current display (for example,
“PassBy”).
Leq Reading- This is the Leq for the Passby event including
all energy between the 10dB down points centered around
the maximum.
SEL Reading - This display shows the total sound energy of
a measurement compressed into one second.
Max Reading - This display shows the maximum sound
pressure level that occurred during the passby.
Date/Time -This displays the date and time of the passby.
Elapsed Time - This shows the elapsed time between the
10dB down points prior to and following the maximum level
measured.
NOTE: The Passby triggering system
can be used to create an exceedance
record of each passby; set “Excd
Trigger” to [Passby].
Wind/Tach
The uand darrow keys can be
used to cycle between the Metrics,
PassBy, and Wind / Tach views.
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The Wind/Tach View has three displays which can be
accessed by simply selecting Wind/Tach with the c Check
key from within the main View menu then cycling through
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the views with the randlarrow keys until the desired
display appears.
Wind-a Display
The Wind-a display consists of five major components:
•
Display label
•
Sound Pressure Level
•
Windspeed
•
Wind Direction
•
Frequency of Windspeed Signal
The Wind-a display is shown below:
Display label
Sound Pressure
Level
Frequency
Windspeed
Wind Direction
The following explains each of the display components:
Display label - This shows the current display (for example,
“Wind-a”).
Sound Pressure Level - This displays the instantaneous
sound pressure level
Windspeed - This displays the instantaneous windspeed.
Wind Direction - This displays the instantaneous wind
direction using compass coordinate points or in degrees.
Frequency - This displays the instantaneous frequency of
the signal from the windspeed transducer. This parameter is
used primarily for troubleshooting.
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Wind-b Display
The Wind-b display consists of seven major components:
•
Display label
•
Live Wind Speed and Direction
•
Average Windspeed
•
Maximum Windspeed and Direction
•
Date/Time of Maximum Windspeed
•
Wind Exceedance Data
•
Windy Threshold Data
The Wind-a display is shown below:
Display label
Live
Average
Maximum
Max Windspeed
Date/Time
Wind Exceedance
Windy Threshold
The following explains each of the display components:
Display label - This shows the current display (for example,
“Wind-b”).
Live Windspeed and Direction- This displays the
instantaneous value of windspeed and direction.
Average Windspeed - This displays the average value of
windspeed calculated since the initiation of the measurement
or since the last data reset.
Maximum Windspeed and Direction- This displays the
maximum value of windspeed and its direction since the
initiation of the measurement or the last data reset.
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Date/Time of Maximum Windspeed - This displays the
data and time of the maximum windspeed.
Windy Exceedance Data - The Windy Exceedance Data
includes the value of the Windy Exceedance Level (in this
instance 40.11) and the number of times the windspeed
exceeded this level.
Windy Threshold Data - The Windy Threshold Data
includes the value of the Windy Threshold Level (in this
instance 5.04) and the percent of the time that the windspeed
was above this level.
Wind-c Percent Display
The Wind-c Percent display consists of three major
components:
•
Display label
•
Live Windspeed
•
Live Wind Direction
•
Percent Windy Condition
•
Windy Directional Distribution
Display label
Live Windspeed
Live Wind Direction
Windy Directional
Distribution
% Windy
The following explains each of the display components:
Display label -This shows the current display (in this case,
“Wind -c Percent”).
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Live Windspeed - The Live Windspeed is the instantaneous
value of windspeed.
Live Wind Direction - The Live Wind Direction is the
instantaneous wind direction, indicated in both compass
coordinates and degrees.
Percent Windy Condition - The Percent Windy Condition
is the percent of the time the windspeed was above the
Windy Threshold Level.
Windy Directional Distribution - The Windy Directional
Distribution is shown on a compass rose with indications of
the percent of the time that windspeed is above the Windy
Threshold Level were in the directions represented by each
of the eight directional coordinates. In this instance we can
see that winds having levels above the Windy Threshold
Level of 5.04 (shown on the Windy-b View) were from the
North West 59% of the time.
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CHAPTER
6
System 824 Virtual
Instruments
System 824 Virtual Instruments
The System 824 presents a number of distinct “virtual
instruments” enabling you to select the mode best suited to a
particular application. You can, of course, create new setups
for particular applications and add your own IDs to the
System 824.
The SLM&RTA (SSA), Logging (LOG) and Integrating
SLM (ISM) instruments are available in various 824
configurations. The table on the next page explains each of
these instruments and shows the configuration in which it is
available.
The following configurations of the System 824 are
available:
•
824S, 824A, 824L, 824
The following options are also available:
•
824-RTA
•
824-FFT
•
824-AUD
•
824-TAL
The table below describes the basic functions of each
configuration.
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System 824 Virtual Instruments
6-1
Instrument
824S
824L
824A
824
ISM - Integrating SLM measures LEQ, SEL, Min, Max,
Peak, with all weights (A, C, Flat) and with all
detectors (slow, fast, and impulse) simultaneously.
Includes a high and low measuring range.






SSA - Sound spectrum analyzer measures LEQ, SEL,
Min, Max, Peak, with all weights (A, C, Flat) and with
all detectors (slow, fast, impulse, peak and Leq)
simultaneously plus 1/1 and 1/3 octave data stored in
time and interval histories at storage rates as fast as 8
times per second. Included are Ln data showing 6 Ln
values, a graph of L1 through L99 (broadband) and
spectral Lns. Wind and Tach data with external
transducers.
LOG - Logging SLM measures LEQ, SEL, TWA, MIn,
Max, Peak, with all weights (A, C, Flat) and with all
detectors (slow, fast, and impulse) simultaneously.
Includes time history, interval history, exceedance
history, daily history, Ln percentiles, statistical data,
exposure, and dual SLM (current and overall). Wind
and Tach data with external transducers.

RTA - High speed spectral data gathering of up to 400
spectra per second using Autostore function. Spatial
averaging of any number of spectra. Flexible triggering
for data acquisition. Performs RT60, RC NCB, HTL.
Exponential and linear detectors.
FFT- 400 line FFT with Hanning, Flat-Top or
Rectangular window, snapshot data storage, display
zoom with a factor of 2, 4, or 8. Count averaging (1 to
16384), measures THD. LInear units can be user
defined.
AUD - Audiometer testing for level, frequency,
linearity, THD, pulse, crosstalk, frequency modulation,
narrow band, broadband, and speech noise.
TAL - Performs complex tonality calculations required
by DIN 45681. Measures the frequency of a dominant
tone (FT), the level of the tone (LT), the bandwidth of
the tonal group (F), the level of the group (LG), and
difference of the two levels (LT - LG). SLM measures
LA, LC, LAeq, LAmax, LCmax, LAFTM5, L95, and LCeq LAeq. A snapshot history is provided to store and
display data from the various modes.
824RTA
824FFT
824AUD
824TAL





This chapter will discuss how to select an ID in addition to
providing an explanation of the features of the currently
available IDs.
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Selecting an Instrument ID
To select one of the System 824 instrument setups or IDs, do
the following:
There will be a ‘>’ to the left of the
currently enabled instrument ID. The
current ID will generally also
remain at the top of the list. If the
user changes the ID that is in use,
the current ID will then have an
asterisk to the left of the title.
Step 1
Step 2
Press the S SETUP key. A menu similar to the
following appears:
Select the desired ID from the menu by using the
uordkeys to highlight it, then press the c
key to select it. That instrument’s main display
will appear:
Sound Spectrum Analyzer (SSA)
There are applications which call for the simultaneous
measurement of both the sound pressure level and the realtime frequency spectrum. Very often you will wish to
measure the weighted (A, C or Flat) sound pressure level
while simultaneously measuring the unweighted frequency
spectrum.
For these applications, the System 824 provides the SSA
instrument.
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System 824 Virtual Instruments
6-3
With this instrument the SLM and RTA functions are
operating simultaneously. The primary indicator range of the
SLM function is 80 dBA, sufficient for most applications.
In operation, the instrument measures four sets of frequency
spectra; the running instantaneous spectrum, the Leq
spectrum, the spectrum associated with the maximum SPL
level that occurred during the measurement and the
minimum bin by bin spectrum. It also gives you a time
history record and Ln centiles. The time history record
stores up to 38 parameters of your choice, including RTA
Leq, RTA Max, or RTA Min, which is determined by the
Time History setup under the settings menu.
SSA Measuring Ranges
By using a 24-bit DSP processor, the digital filters of the
System 824 meets the specifications of IEC 61260 - Class 1
and ANSI S1.11-1986 Type 1-D over a linearity range
exceeding 80 dB. The dynamic range of the analysis
function, from noise floor to overload, is 85 dB (typical).
Eight ranges are available, providing gain to +50 dB and
attenuation to -20 dB in 10 dB steps.
The following presents the Measuring Ranges available for
SPL, Peak and 1/3 Octave Filter measurements for the SSA
instrument:
Measurement Range (SSA mode only)
AW
CW
FLT
16.0
31.5
63.0
125
250
500
1000
2000
4000
8000
NF
33
32
32
2
3
4
2
3
12
10
15
14
14
0dB Gain
Start End Range
48
128
80
48
128
80
48
128
80
45
128
83
43
128
85
40
128
88
40
128
88
37
128
91
33
128
95
32
128
96
32
128
96
32
128
96
32
128
96
NF
24
23
25
2
1
0
-2
-3
4
2
6
7
7
10dB Gain
Start End Range
38
118
80
38
118
80
38
118
80
35
118
83
35
118
83
33
118
85
27
118
91
25
118
93
25
118
93
20
118
98
20
118
98
20
118
98
20
118
98
*NF is noise floor
Start = start of linearity range
6-4
NF
15
16
21
1
1
1
-3
-3
-3
-4
-2
0
1
20db Gain
Start End Range
28
108
80
28
108
80
33
108
75
25
108
83
23
108
85
23
108
85
28
108
80
15
108
93
15
108
93
15
108
93
15
108
93
15
108
93
15
108
93
NF
8
9
21
2
2
0
-2
-4
-4
-5
-5
-2
-1
30dB Gain
Start End Range
23
98
75
23
98
75
33
98
65
25
98
73
25
98
73
22
98
76
18
98
80
15
98
83
13
98
85
13
98
85
13
98
85
13
98
85
13
98
85
NF
7
8
26
-1
-4
-7
-9
-10
-10
-10
-8
-6
-2
40dB Gain
Start End Range
20
88
68
20
88
68
33
88
50
28
88
60
22
88
66
15
88
73
11
88
77
8
88
80
6
88
82
6
88
82
8
88
80
8
88
78
12
88
76
NF
6
8
23
1
-4
-7
-8
-9
-10
-10
-8
-6
-3
50dB Gain
Start End Range
20
78
58
20
78
58
40
78
38
23
78
55
23
78
55
18
78
60
8
78
70
8
78
70
8
78
70
8
78
70
8
78
70
8
78
70
13
78
65
A-weighting, C-weighting, and Flat are measured to
ANSI S1.4 and IEC 60651 standards for SLM linearity.
1/3 octave filters listed are measured to the IEC 61260
standard for Class 0 linearity which is ±0.3 dB. The numbers in the table represent SPL levels with a typical
824 Reference Manual
2/6/17
377B41 microphone which has 44.1 mV/Pa sensitivity.
LN Percentiles (Spectral)
The System 824 LN Centiles feature provides a display
showing the six Ln values of one selected 1/3 octave filter.
It also displays spectra for the six Ln percentiles.
AC/DC Output
The AC/DC output on the 824 is through the 3.5mm stereo
connector at the bottom of the instrument. This is a 2channel output. A mono plug should NOT be used, it will
short the “ring” signal to ground.
AC Output (Tip)
AC or DC Output (Ring)
Ground (Sleeve)
The two possible output signals are on the tip and the ring of
the 3.5mm jack. The sleeve is ground. The selection in the
824 controls settings lists the signal output on the tip first,
followed by the signal output on the ring. The AC output
signal is always amplified or attenuated by the gain or
attenuation selected for the instrument. For example, if one
2/6/17
System 824 Virtual Instruments
6-5
were using an SSA instrument with 20dB of gain, the AC
output would also have 20 dB of gain from the input*.
*Also take into account a gain of
approximately -0.25 dB in the
PRM902 preamplifier.
The DC output voltage is proportional to the SPL specified
by the weighting setting according to this formula
SPL =   Vout   0.0275  + StartLevel
StartLevel is a setting on the Ln settings menu. DC out has a
range of 120 dB.
The output signals will vary based on which instrument type
is used. For LOG and ISM instruments, the following table
defines the output signals.
LOG and ISM Instrument AC and DC Output Settings
824 Menu
3.5mm Connector Tip (Black/White)
3.5mm Connector Ring (red)
AC-1 AC-2
FLAT AC out
FLAT AC out with 30dB gain
AC-1 DC
FLAT AC out
Weighted DC out
AC-2 DC
FLAT AC out with 30 dB gain
Weighted DC out
AC-2 AC-1
FLAT AC out with 30 dB gain
FLAT AC out
For SSA instruments, the following table defines the output
signals (output amplitude based on input Gain setting).
SSA Instrument AC and DC Output Settings
824 Menu
3.5mm Connector Tip (Black/White)
3.5mm Connector Ring (red)
AC-1 AC-2
FLAT AC out
CWT AC out
AC-1 DC
FLAT AC out
Weighted DC out
AC-2 DC
CWT AC out
Weighted DC out
AC-2 AC-1
CWT AC out
FLAT AC out
The DC output is generated digitally
from the SPL but is slower than the
SLOW or FAST detector response
with an exponential time constant of
approximately 2.25 seconds.
6-6
For the AUD instrument, AC-1 is on the tip and the DC
output is not used.
For the RTA instrument, the AC signal will be identical on
the tip and ring.
824 Reference Manual
2/6/17
Logging SLM
The Logging SLM (LOG) instrument is ideal for
applications requiring the automatic measurement and
storage of multiple parameters over an extended period as
required for environmental noise monitoring. The Logging
SLM provides automatic logging of sound level parameters
including Interval data, Ln statistics, noise event detection
and event time history records. Additionally, this mode
provides a dynamic range of 115 dB.
Like other instrument modes, the Logging SLM mode is
selected via the Setup menu. This section covers some of the
data acquisition features of the LOG instrument.
Time History
The System 824 Time History logs Leq readings and up to 37
additional parameters. The Time History graphical display
allows you to scroll through the time history and Run/Stop
events.
Interval History
The following Interval History parameters can be logged at
user-selectable time intervals between 1 second and 99
hours (hh:mm:ss)
2/6/17
•
Lmax, Lmin, SEL, and Leq (q=3) or Time Weighted Average (q=4, 5, or 6) levels for a selected detector (Slow,
Fast, or Impulse) and a selected frequency weighting (A,
C, or Flat)
•
Lpeak level corresponding to the frequency weighting
selected for Leq (see above) and a second Lpeak level corresponding to one of the two alternative choices of frequency weighting.
•
Ln (6 values with 0.1 dB resolution, based on userselected percentages with 0.1% resolution)
System 824 Virtual Instruments
6-7
•
Date, Time and Duration of Interval
•
Average and maximum wind conditions (using external
windspeed/direction transducers)
Exceedances
The 824 can log exceedance events based on sound levels
that go over a predefined threshold. It can also be triggered
by an event which raises the level by 10 dB. This is called a
“Passby” event.
LN Percentiles (Broadband)
The System 824 LN Centiles feature provides a set of six
percentile values to be measured and shown in the “LN
Centiles” display. Using these six settings, you can select
any six percentile values. For example, setting one of the six
settings to 10.5 would show the SPL that has been exceeded
10.5% of the time during the time of overall measurement.
These settings can each take on any value within the
following range:
.01 to 99.99
Sound Exposure
The System 824 lets you set the criteria level and criterion
time for Dosimetry measurements. A 100% dose occurs if a
person is exposed to a constant sound field with a SPL equal
to the criterion level, for the criterion time or full dose hours.
6-8
824 Reference Manual
2/6/17
The criterion level setting can take on any integer value
within the following range:
0 to 255 dB
Exposures at higher sound exposure levels than the overall
criterion level will result in a 100% dose in less time; or, if
exposure continues, the overall dose will exceed 100%.
The following are examples of the System 824 Sound
Exposure displays:
LOG and ISM Measuring Ranges
The following table presents the typical RMS detectors
measuring ranges for the LOG and ISM instruments:
Frequency Weighting
Range
A
C
Flat
Low Range
20–108 dB
25–108 dB
25–108 dB
Normal Range
23–128 dB
28–128 dB
30–128 dB
High Range
43–148 dB
48–148 dB
50–148 dB
NOTE: Ranges are in dB SPL using a
typical 377B41 microphone with 44.1
mV/Pa
sensitivity.
See
“RMS
Measurement Range (LOG and ISM
modes only)” on page C-11 for more 824
specifications.
2/6/17
The LOG and ISM instruments have a dynamic range of 105
dB.
System 824 Virtual Instruments
6-9
6-10
824 Reference Manual
2/6/17
CHAPTER
7
Using ID Setting Files
The System 824 makes it easy to make the measurements
you need through stored instrument definitions (ID). You
can select one of the permanent ID’s or you can create your
own library using the 824’s keypad or the 824 Utility software. This chapter will describe how to recall (or activate)
an ID, customize it to suit your specific needs and then save
it for later use. The details on each setting is described for
the SSA, ISM and LOG instrument types.
This chapter covers the following:
•
Recalling ID Setting Files
•
Customizing Settings
•
Menu Layout of SLM&RTA (SSA) Settings
•
Menu Layout of High Dynamic Range Integrating SLM
(ISM) settings
•
Menu Layout of Logging (LOG) SLM Settings
•
“Check Menus”
Recalling ID Setting Files
The procedural steps for recalling an ID setting file is
identical for all the instrument types (i.e. SSA, LOG, ISM).
The S SETUP key activates a menu that lists the active ID
and all stored ID’s. They are sorted in the order of most
recently used first. If an ID is permanent, i.e. created by
Larson Davis and not detectable or changeable, it will have a
“p” just to the left of its’ name in the SETUP menu. These
permanent ID’s are a good starting point for creating your
own custom ID.
2/6/17
Using ID Setting Files
7-1
If you have taken data that has not
been stored or if the instrument is
not reset, you will be prompted with
“Data not Saved. Save?”. Answer
Yes to save the data, No to have the
data reset or cancel to cancel the ID
recall.
To activate an ID, press the down dor up uarrow
keys to highlight it and press the CHECK c key. The ID is
then recalled, the menu closes and one of the previously
viewed displays is shown. Data using these settings may
now be taken or the settings may be further customized for
your application.
NOTE: If any changes have been made to the current
settings you will be prompted with “Active ID has Changed.
Save?”
Customizing Settings
This section gives an example of using the standard settings
in the SSA instrument. The procedures in this example can
be applied to the other Model 824 modes and instruments by
simply substituting the other instruments’ specific settings
for those of the SSA instrument.
Settings Example - SLM&RTA (SSA)
There are four general steps to setting up the SSA
instrument: 1) Press the SETUP key. 2) Select the
SLM&RTA SSA setting. 3) Press the SETUP key again. 4)
Enter the EDIT Settings menu.
The following steps you through the example procedure of
setting the SLM&RTA (SSA) instrument’s Detector setting
to Fast.
If the 824 is already in SSA mode,
there will be a ‘>’ to the left of
“SLM&RTA SSA”. In which case,
skip to Step 3 below.
7-2
Step 1
Press the S SETUP key. A menu similar to the
following appears:
824 Reference Manual
2/6/17
If you have not already saved your
data, you will be prompted to save it
at this step.
Step 2
Select SLM&RTA SSA from the menu by using
the u or dkeys and then pressing the c
Check key. The SLM+RTA screen appears:
The System 824 is now set to the SLM&RTA (SSA)
instrument.
2/6/17
Step 3
To access the Settings menu, press the S Setup
key. The Edit Settings: SLM&RTA SSA is highlighted as the Setup menu appears:
Step 4
Press the rkey and the Settings menu for the
SLM&RTA (SSA) instrument appears:
Step 5
Using the uord keys, highlight the SLM
option and press the c Check key.
Using ID Setting Files
7-3
Step 6
Use the uor dkeys to highlight the Detector setting, then press therkey or the c
Check key. The Detector Settings menu appears:
Step 7
In the pop-up windows use the uor dkeys
to highlight the Fast setting, then press the c
Check key to accept the setting change. The
SLM&RTA (SSA) instrument’s Detector setting is
now set to Fast. Press the S Setup key to close
the menu and return to the SLM+RTA view.
Settings Descriptions
Within the Edit Settings menu, use
the u and d keys to move
from one setting to the next. Use
therkey or c Check key to
select the setting to be modified. The
l key is used to return to
previous menus.
7-4
Descriptions of the System 824 instrument’s various settings
are provided in this section. The following will be covered:
•
“Common SLM Settings”
•
“Common Control Settings”
•
“Logging SLM TWA Settings”
•
“Logging SLM Triggering Settings”
•
“LOG and SSA Ln Settings”
•
“LOG and SSA Time History Settings”
824 Reference Manual
2/6/17
•
“Logging SLM Interval Settings”
•
“Logging SLM Exceedance History Settings”
•
“Logging SLM Daily History Settings”
•
“Logging SLM Define Report Settings”
In the following sections, headings for each setting or
display mode will identify in parentheses the particular
System 824 instruments to which they pertain, as shown in
the following example.
Example:
Title Setting - (SSA, LOG, ISM)
Common SLM Settings
The SSA, ISM, and LOG instrument types include standard
SLM functions. This section covers the available SLM
settings for these instruments.
Title Setting - (SSA, LOG, ISM)
To change the Title, use the r
and lkeys to select each
character. Use the u and d
keys to replace the selected letter.
Pressing the R Reset key clears all
characters from the cursor to the end
of the field.
Use the Title setting to create a title or header for printed
reports. This title/header will be placed at the top of each
report you print.
Detector Setting - (SSA, LOG,
ISM)
Detector - selects the detector rate of the instrument’s RMS
detector. This setting provides the following three options:
The 824 measures all three
frequency weightings with three
detectors simultaneously and all
nine of these levels can be viewed.
2/6/17
Slow - An exponential average with a one second
time constant.
Fast - An exponential average with a 1⁄8 second
time constant.
Using ID Setting Files
7-5
There are certain features (such as
event counting) that function only
with one selection of frequency
weighting and one selection of
detector, both user selected. These
same weighting and detector
selections also determine the metrics
used for features such as LN,
Intervals, Exceedances, etc.
Weighting Setting - (SSA, LOG,
ISM)
Impl - An impulse detector which has a very fast
rise time (a 35 mS time constant) but a very slow
decay time.
Weighting - selects the desired frequency weighting for the
RMS and secondary peak detectors. The Weighting setting
provides the following three options:
A - The instrument uses an A-weighted input filter.
C - The instrument uses a C-weighted input filter.
FLT - The instrument uses Flat weighting (see
specifications for passband frequency in Appendix
C).
Gain Setting - (SSA)
The Gain setting is only available in
the SSA instrument. The -10 and -20
dB gain settings are not available for
electret or direct transducer types
(see “Transducer”).
Gain - The gain setting sets the measuring range of the
instrument in 10 dB steps by adjusting the amplification of
the microphone’s signal. The gain is set from the SSA Setup
Menu, highlighting and selecting SLM, then Gain to obtain
the following Gain Menu.
In the display, the lowest and highest levels that can be
measured accurately are indicated by each live display’s
graph scale. The following selections are available:
7-6
824 Reference Manual
2/6/17
NOTE: If Gain is set to -10 or -20 dB
and the microphone type is not
condenser then the gain is set to 0 dB
and the warning “Setting Conflict”
is displayed.
-20, -10, 0, +10, +20, +30, +40, +50
Use the u and d keys to highlight the desired value
of gain and press c Check key.
Range Setting - (LOG, ISM)
The Range setting is only available
to the LOG and ISM instrument.
Range selects the measurement range you desire for the
instrument. This setting provides the following three
options:
NOTE: If Range is set to “Low” and
the microphone type is not condenser
then the range is set to “Normal”
and the warning “Setting Conflict”
is displayed.
Normal - The instrument’s available dynamic
range is positioned in the “normal” range which is
typically 20dB to 130dB when using a Larson
Davis high-sensitivity microphone.
High Range is not available for
electret or direct transducer types
(see “Transducer Setting” below).
High - The instrument’s sensitivity is reduced by
20dB, which has the effect of moving the instrument’s available dynamic range upward relative to
the “normal” range. Therefore you can measure
higher-level sounds effectively. The benefit varies
depending upon the weighting or octave filter that
you are using.
2/6/17
Low - The instrument’s input circuitry provides an
additional 20dB of gain which has the effect of
moving the instrument’s available dynamic range
downward relative to the “normal” range. The net
effect is that you can measure lower-level sounds
effectively. The degree of benefit varies depending
upon the weighting or filter that you are using.
Using ID Setting Files
7-7
NOTE: The Range setting is not meant to
be switched dynamically in real time—in
part because selecting the “High” option
requires
a
stabilization
period.
Furthermore, the System 824’s large
dynamic range (110dB) often makes
dynamic range switching unnecessary.
The Range setting merely allows you to
move the available dynamic range either
up or down when you need to measure
extremely high or low sound levels.
Transducer Setting - (SSA,
LOG, ISM)
Transducer sets the desired transducer. This setting provides
the following three settings:
NOTE: Using an electret microphone
with the polarization voltage supplied
with the “condnsr” option, will change
the
microphones
sensitivity
and
frequency response characteristics.
Condnsr - This indicates that the microphone
being used is an air condenser type and the System
824 will generate the appropriate polarization
voltage to make it function properly.
The frequency characteristics of the
377B41 & 377A60 microphones
change sufficiently enough in high
range as to no longer meet Type 1
standards. Thus we recommend
using
the
normal
sensitivity
microphones, such as 2540 & 2559
to measure high amplitude signals.
Elctret - This indicates that the microphone being
used is an “electret” (pre-polarized) microphone.
The instrument will not generate any polarization
voltage.
Direct - This indicates that no microphone is
being used and that electrical signals are being
injected directly into the preamp. The instrument
will not generate any polarization voltage.
The transducer setting is a system
setting that is not saved or recalled
with an ID even though it appears in
the SETUP menu.
Random Incidence Microphone
Correction - (Available to all
Instrument types)
See “Random Incidence Microphone
Correction” on page C-24 for the
random incidence correction filter’s
response.
7-8
The Random Corr setting gives you the option of turning on
a digital filter to provide the correction necessary to provide
a random incidence response when measuring with a 2540
or 377B41 free-field microphone.
No - Random incidence correction is turned off.
Yes - Random incidence correction is turned on.
824 Reference Manual
2/6/17
NOTE: Interval Spectral LNs will not be available when
R.I. Correction is turned on. Overall Spectral LNs will only
be available when the 824 is stopped. This means that the
overall Spectral LN data will not be viewable when the 824
is running. If you try to view the overall Spectral LN data
while the 824 is running the message “Calculating/Stop to
View” will be displayed.
Pk Weighting - (SSA, LOG, ISM)
The 824 has peak detectors for A, C, and Flat frequency
weighting that measure simultaneously the greatest
instantaneous level (Lpk) that has occurred since the last
current or overall reset. Some histories and event counters
are only able to evaluate one of the three peak detectors. The
Peak Weighting Setting selects which is to be used for these
features.
PK-II uses the normal weighting
setting.
Peak Weighting allows you to select either A, C, or Flat
weighting for the primary peak detector, PK-I.
This setting provides the following three options:
A - The A-weighted peak detector is used.
C - The C-weighted peak detector is used.
Flat - The Flat Weighted peak detector is used.
RTA Detector Setting - (SSA)
With the RTA Detector setting you can set the time
averaging characteristics for real-time frequency analysis.
This setting provides the following two options:
Slow - The frequency analysis uses exponential
averaging with a one second time constant.
Fast - The frequency analysis uses exponential
averaging with a 1⁄8 second time constant which
allows more variability to appear in the measurement.
RTA Weighting - (SSA)
The RTA Weighting setting allows you to display an A, C,
or Flat weighted spectrum. An overall reset is required
before this parameter can be changed.
A - Displays an A weighted spectrum
C - Displays a C weighted spectrum
2/6/17
Using ID Setting Files
7-9
FLT - Displays a Flat weighted spectrum
Bandwidth Setting - (SSA)
NOTE: The SSA instrument only
measures data using 1/3 octave filters.
When 1/1 octave filtered data have been
selected, the energy in 1/3 octave band
data are summed to give octave filter
data. When using the translator function
in the 824Util program both 1/1 and 1/3
octave data are provided.
The Bandwidth setting provides displaying of either fulloctave or third-octave bandwidth filters for real-time
frequency analysis. This setting has the following two
options:
1/1 - Displays octave band filters.
1/3 - Displays third-octave band filters.
Common Control Settings
Control settings are also available from some check menus
as discussed later in this chapter.The Control settings are
available on most System 824 instruments. The Control
settings are available on most System 824 instruments.
Control Settings - (ISM)
For the ISM instrument, the control settings can be accessed
through the “Edit Settings” menu as the last selectable menu
item, Controls.
Control Settings _(SSA, LOG)
For the SSA and Logging instrument, the control settings are
also accessed through the “Edit Settings” menu, except that
the last selectable menu item is Advanced. Using the
uand darrow keys, highlight the Controls item, then
select it using the r arrow key or the c Check key.
Use the u and d keys to move
from one setting to the next. Then use
the r key to change the selected
setting. The l key is used to
return to previous menus.
7-10
824 Reference Manual
2/6/17
Triggering for the SSA instrument is
for Logic out only. If Logic-Out is set
to “RMS”, the 824 looks at the level
set under “SPL Excd Lvl 1”. See the
section “LOG and SSA Triggering
Settings” on page 7-22.
Using the uand darrow keys, highlight the Controls
item, then select it using the r arrow key or the c Check
key. Whether for the ISM, SSA or LOG instrument, the
Controls menu will be as shown below.
The following is the menu layout for the control settings:
2/6/17
Menu Items
Available Settings Options
AC/DC Output
AC-1
AC-1
AC-2
AC-2
Logic-In Mode
None
Pause
Toggle
Level
Alarm
Using ID Setting Files
AC-2
DC
DC
AC-1
7-11
Logic-Out
Off
RMS
Peak
R+P
Intv
R+I
P+I
R+P+I
A:D
R+A
P+A
R+P+A
I+A
R+I+A
P+I+A
R+P+I+A
R/S
Excd
Logic-Out Time
0 - 255 sec
Logic-Out #2
Same settings as Logic-Out
Logic-Out #2
Timer
0 - 255 sec
Heater On
Yes/No
E.A. Cal Tone
Yes/No
NOTE: Menu items Logic-In Mode
through Logic-Out #2 Timer are
system settings that are not stored or
saved with an ID even though they
appear in the SETUP menu
NOTE: The Logic-out #2, uses the
Heater output line if set to something
other than off.
AC/DC Output Settings - (SSA,
LOG, ISM)
The AC/DC Output on the 824 allows the user to select what
type of signal will be sent out the 3.5mm connector at the
base of the instrument. See the section “AC/DC Output” on
page 6-5 for more details.
Logic Input Setting - (SSA,
LOG, ISM)
The SSA instrument can access the
Logic-input Mode setting through
either the Check or the Setup menus.
7-12
The Logic Input sets the functionality of the logic input pin
on the control connector (pin 3). This pin is intended to be
connected to an external switching device—possibly a pushbutton switch. The external switching device will either
connect the pin to +5V (pin 6) or unconnected. This signal
may also be supplied from another device that can supply a 0
to +5 volt logic signal (input load impedance is 100K ohms).
824 Reference Manual
2/6/17
The resulting logical state (high or low) will determine what
occurs inside the instrument as a function of this Logic
Input setting. Accordingly, the setting provides the
following five options:
None - The state of the logic input pin has no
effect.
Pause - Whenever the logic input is connected to
+5V (e.g. when a push-button switch makes contact), the instrument pauses when in the run mode.
Toggle - Each time the logic input is connected to
+5V, (e.g. switch makes contact) the instrument
runs or stops. The effect is the same as pressing
the s Run/Stop key.
Caution: The Level setting overrides
the RUN/STOP key and I/O Run/Stop
function commands.
Level - When the logic input is connected to +5V,
(e.g. switch makes contact) the instrument runs.
When the logic input is disconnected from +5V
(e.g. switch breaks contact), the instrument stops.
Alarm - When the logic input is connected to +5V
(e.g. switch makes contact), the instrument initiates a dial-out sequence. This option is intended
for use only with advanced remote monitoring
applications where the instrument is paired with a
modem.
Logic Output Setting - (SSA,
LOG, ISM)
2/6/17
The Logic Output (2 outputs are available) selects the
functionality of the logic output pin on the control
connector (pin 2 referenced to ground, which is on pin 1)
and the heater output (pin 8, pulled to ground). You can use
these Logic Outputs to actuate external devices during
certain events or combinations of events that occur in the
instrument. The option you select determines which types of
events will trigger a logic output line.
Using ID Setting Files
7-13
NOTE: In many of the options below,
notice the use of a shorthand identifier
which includes the first letters of the
various events along with the plus +
symbol. The plus symbol indicates a
logical “OR” function between events.
In other words, if for a given option, any
one of the listed events occurs alone or in
combination with another event, the
logic output will turn on.
The Logic Output setting provides the following options:
Off - The Logic Output is disabled.
RMS - The Logic Output turns on when an RMS
exceedance event occurs. An RMS exceedance
event occurs when the RMS sound pressure level
(SPL) exceeds the threshold set by the SPL Trigger Level setting. The Any-Data SPL used is the
one specified by the Weight and Detector settings
Peak - The Logic Output turns on when the
instantaneous peak level (Peak-I) specified by the
Peak Weight setting is over the Peak-1 Exceedance Level, or when the instantaneous weighted
peak level (Peak-II) specified by the Weight setting is over the Peak-2 Exceedance level.
R+P - The Logic Output turns on when either an
RMS or Peak exceedance event occurs.
Intv - The Logic Output turns on when an interval
begins.
R+I - The Logic Output turns on when an RMS
exceedance event occurs or when an interval
begins.
P+I - The Logic Output turns on when any peak
exceedance event occurs or when an interval
begins.
R+P+I - The Logic Output turns on when either
an RMS or peak exceedance event occurs or when
each interval begins.
The A:D (or ‘A’) functions are for
compatibility with systems that have
analog data acquisition, generally
used to record weather metrics.
A:D - The Logic Output turns on when an event
on one of the A:D channels occurs. These A:D
channels are typically used for weather monitoring.
R+A - The Logic Output turns on when an RMS
exceedance event occurs or when an event occurs
on one of the A:D channels.
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P+A - The Logic Output turns on when a Peak
exceedance event occurs or when an event occurs
on one of the A:D channels.
R+P+A - The Logic Output turns on when either
an RMS or Peak exceedance event occurs or when
an event occurs on one of the A:D channels.
I+A - The Logic Output turns on when each interval begins or when an event occurs on one of the
A:D channels.
R+I+A - The Logic Output turns on when an
RMS exceedance event occurs, when each interval
begins, or when an event occurs on one of the A:D
channels.
P+I+A - The Logic Output turns on when a Peak
exceedance event occurs, when each interval
begins, or when an event occurs on one of the A:D
channels.
R+P+I+A - The Logic Output turns on when
either an RMS or Peak exceedance event occurs,
when each interval begins, or when an event
occurs on one of the A:D channels.
R/S - The Logic Output turns on when the instrument is in run mode and turns off when the instrument is in stop mode.
Excd - The Logic Output turns on when a valid
exceedance is detected and after it’s minimum
duration has been met.
Logic Output Time Setting (SSA, LOG, ISM)
The Logic Output Time sets the number of seconds that the
logic output will remain turned “ON” following a triggering
event. Accordingly, this setting can take on any integral
value within the following range:
(0)sec to (255)sec
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7-15
NOTE: If set below 5 seconds, the output
will remain “ON” as long as the
conditions are true, and turn “OFF” x
seconds (0 to 5) after the condition; if set
to 6 seconds or greater, the output will
stay “ON” for at least 5 seconds but will
turn “OFF” as soon as the condition
becomes false or the condition has lasted
the number of set seconds (i.e. 0-5
minimum time, 6-255 maximum time).
Logic Output #2
Logic-Out #2 works the same as Logic Output and has the
same options as shown above.
NOTE: When Logic-Out #2 is not off
then the Heater Control setting has no
effect. It is overridden by Logic-Out #2.
Logic Output #2 Time Setting
The Logic Output #2 Time sets the number of seconds that
the output will remain turned “ON” following a triggering
event. See Logic Output Time setting above.
Heater On
The Heater Control output selects the functionality of pin 8
of the control connector. It is an “open drain” output such
that when asserted, the Heater output sinks current to
ground; when unasserted no current flows. It has a
maximum rating of 40 volts.
The “Heater On” setting provides the following options:
No - Is unasserted; which is considered OFF (line
can be used as Logic output #2)
Yes - Is asserted; which is considered ON
E. A. Cal Tone
The E. A. Cal Tone setting is used to manually control the
Electrostatic Actuator (E. A.) of an outdoor microphone
system. It is a CMOS output that drives from 0 to +5 volts
through a 10,000 ohm current limiting resistor to pin 7 of the
control connector; +5 volts is the asserted state.
Logging SLM TWA Settings
The Time Weighted Average (TWA) settings are available to
the Logging SLM (LOG) instrument. In a few cases, the
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ISM instrument also provides access to a few of the TWA
settings.
Use the u and d keys to move
from one setting to the next. Then use
the r key to change the selected
setting. The l key is used to
return to previous menus.
The following table shows the TWA settings as found in the
LOG instrument. Each setting is later described in greater
detail.
.
Menu Items
Available Settings Options
Ovll Exchange
3dB
4dB
5dB
6dB
Ovll Threshold
0 - 255 dB
Ovll Criterion
0 - 255 dB
Criterion Time
0 - 99 hours
Crnt Exchange
3dB
4dB
5dB
6dB
Crnt Threshold
0 - 255 dB
Crnt Criterion
0 - 255 dB
Ovll Exchange - (LOG)
This setting affects the System 824’s
primary or overall memory buffer.
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The Overall Exchange rate setting sets the exchange rate
(sometimes called the “doubling rate”) that is used to
calculate the overall TWA. The exchange rate reflects the
relationship between the permitted exposure levels and the
exposure duration. Selecting an exchange rate of 5dB, for
example, means that 5dB may be added to the permissible
exposure level every time the exposure duration is cut in
half. This setting provides the following four options:
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7-17
The formulas for TWA can be found
in “Integrated Level Calculations”
on page B-1.
3dB - The default 3dB option is the most commonly
used and results in the Leq time weighted average.
(When a threshold of 0 is used.) It is used internationally and for measurements that comply with U.S.
Environmental Protection Agency (EPA) regulations.
4dB - The 4dB option results in the LDOD time
weighted average which is used for measurements
that comply with U.S. Department of Defense (DOD)
regulations.
5dB - The 5dB option results in the LOSHA time
weighted average which is used for measurements
that comply with U.S. Occupational Safety and
Health Administration (OSHA) regulations.
6dB - The 6dB option results in the LAvg time
weighted average which is merely a convenient representation of the long-term average noise level as
opposed to the RMS noise level.
Ovll Threshold - (LOG)
This setting affects the System 824’s
primary or overall buffer.
The Ovll Threshold setting sets the threshold for computing
the overall time weighted average (TWA).
As per the requirements of various regulatory agencies, only
those sound levels which are above a certain threshold level
are used when computing the TWA. Accordingly, this
setting can take on any integer value within the following
range:
0 - 255 dB
For hearing conservation measurements, set the threshold to
80dB. For most community noise measurements, set the
threshold to 0dB. (When set to 0, all levels are included)
Ovll Criterion - (LOG)
The Ovll Criterion setting sets the TWA level which
constitutes 100% dose for the overall measurement. The
100% dose occurs if a person is exposed to that level for the
criterion time. Accordingly, this setting can take on any
integer value within the following range:
0 to 255 dB
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Exposures at higher levels than the overall criterion level
will result in a 100% dose in less time; or, if exposure
continues, the overall dose will exceed 100%.
Criterion Time - (LOG)
The Criterion Time determines how long exposure to the set
TWA level can occur before 100% dose occurs for the
overall measurement.
Crnt Exchange - (SSA, ISM,
LOG)
In the ISM instrument the Crnt
Exchange setting is a submenu to the
SLM menu selection.
The Crnt Exchange rate setting sets the exchange rate
(sometimes called the “doubling rate”) that calculates the
current TWA. The exchange rate reflects the relationship
between the permitted exposure levels and the exposure
duration. Selecting an exchange rate of 5dB, for example,
means that 5dB may be added to the permissible exposure
level every time the exposure duration is cut in half. This
setting provides the following four options:
This setting affects the System 824’s
secondary or current buffer.
3dB - The Crnt Exchange defaults to the 3dB
option. This provides a Leq time weighted average in
accordance with European common usage in addition
to compliance with U.S. Environmental Protection
Agency (EPA) regulations.
4dB - The 4dB option results in the LDOD time
weighted average which complies with U.S. Department of Defense (DOD) regulations.
5dB - The 5dB option results in the LOSHA time
weighted average which complies with U.S. Occupational Safety and Health Administration (OSHA) regulations.
6dB - The 6dB option results in the LAvg time
weighted average which provides a convenient representation of the long-term average noise level as
opposed to the RMS noise level.
Crnt Threshold (SSA, ISM,
LOG)
In the ISM instrument the Crnt
Threshold setting is a submenu to the
SLM menu selection.
2/6/17
The Crnt Threshold sets the threshold for computing the
current time weighted average (TWA).
Using ID Setting Files
7-19
This setting affects the System 824’s
secondary or current buffer.
In compliance with the requirements of various regulatory
agencies, only those sound levels which are above a certain
threshold level are used when computing the TWA.
Accordingly, this setting can take on any integer value
within the following range:
0 - 255 dB
For hearing conservation measurements, set the threshold to
80dB. For most community noise measurements, set the
threshold to 0dB.
Crnt Criterion (LOG)
The Crnt Criterion sets the TWA level which constitutes
100% dose for the current measurement. The 100% dose
occurs if a person is exposed to that level for the criterion
time or full dose hours. Accordingly, this setting can take on
any integer value within the following range:
0 to 255 dB
Exposures at higher levels than the current criterion level
will result in a 100% dose in less time; or, if exposure
continues, the current dose will exceed 100%.
LOG and SSA Ln Settings
Ln Settings are available in the
Logging SLM (LOG) and SLM&RTA
(SSA) instruments.
Ln is the SPL which was exceeded n% of the time. The Ln’s
are computed from the overall level distribution histogram
or each Interval’s level histogram. The measured and
displayed Ln percentage settings may be changed during the
measurement. The six Ln’s are automatically listed in
increasing order.
Use the u and d keys to move
from one setting to the next. Then use
the r key to change the selected
setting. The l key is used to
return to previous menus.
The following is a table of the LN settings:
7-20
Menu Items
Available Settings Options
Enable Ln (SSA
only)
No
Yes
Start Level
0-99 dB
Ln 1 Percent
0.00 to 99.99%
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Ln 2 Percent
0.00 to 99.99%
Ln 3 Percent
0.00 to 99.99%
Ln 4 Percent
0.00 to 99.99%
Ln 5 Percent
0.00 to 99.99%
Ln 6 Percent
0.00 to 99.99%
Spectral Ln (SSA
only)
None
Overall
Interval
NOTE: Interval Spectral LNs will
not be available when R.I.
Correction is turned on.
NOTE: An Ln percentage of 0 provides
Lmax for the Ln level.
Enable Ln
This function turns on or off the automatic storage of the six
Ln percentile levels for the overall measurement.
No - The six Ln levels are not stored for the overall measurement.
NOTE: If Lns are enabled in the SSA
instrument, then the Back-Erase feature
is no longer available. (See the section
“Pause, Back Erase” on page 3-10 for
information on the Back-Erase feature)
Yes - The six Ln levels are stored for the overall
measurement.
Start Level
The Start Level allows you to set the minimum decibel level
to be included in the statistical histogram and calculated Ln
Percentiles.
Ln’s
The LN Centiles set the six percentile values to be measured,
logged (if selected) and shown in the Ln displays. Using
these six settings, you can select any six percentile values.
As shown above, these settings can each take on any value
within the following range:
0.00 to 99.99%
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7-21
Whenever you change any percentile value, the instrument
sorts and reorders the percentile values into ascending order
as demonstrated in the following example:
Suppose you change Ln 3 from 30.0* to 5.0*. The original
setting values will then be automatically sorted into
ascending order and reassigned as shown in the table below:
Spectral Ln’s (SSA only)
Original Setting
After Change and Sort
Ln 1 Percentile = 10.0
*Ln 1 Percentile = 5.0
Ln 2 Percentile = 20.0
Ln 2 Percentile = 10.0
*Ln 3 Percentile = 30.0
Ln 3 Percentile = 20.0
Ln4 Percentile = 40.0
Ln 4 Percentile = 40.0
Ln 5 Percentile = 50.0
Ln 5 Percentile = 50.0
Ln 6 Percentile = 60.0
Ln 6 Percentile = 60.0
The Spectral Ln setting is used to measure six Ln values for
each 1/3 octave. The setting options provided are:
Spectral Lns can be enabled as an
Overall measurement or as a
function of each Interval History
record.
None - Spectral Ln’s are turned off.
To store interval spectral Ln levels,
set “Spectral Ln” to “Interval”,
enable Ln and Interval histories and
set “Intv Save Ln” to “Yes”.
Interval - Spectral Ln’s are computed for each
interval period.
Overall - Spectral Ln’s are computed for the overall measurement.
NOTE: If Random Corr. is set to [Yes] and Spectral Ln is set
to [Interval] then Spectral Ln will be set to [None] and the
warning “Setting Conflict” is displayed.
LOG and SSA Triggering Settings
For the SSA instrument, these
trigger settings are used to control
the logic output line.
7-22
Trigger levels can be set as follows: two for the SPL (RMS
value) and one each for Peak I and Peak II. These levels are
used with the LOG instrument to count the number of
exceedances during the measurement period and display that
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2/6/17
number in the Stats-a and Stats-b displays. They also define
the triggering of noise events or exceedances when using the
Logging SLM Mode.
The Stats displays are only available
to the LOG instrument.
Use the u and d keys to move
from one setting to the next. Then use
the r key to change the selected
setting. The l key is used to
return to previous menus.
The following is a table of the Triggering Menu settings.
Each setting is then described in greater detail.
Menu Items
Available Settings Options
SPL Excd Lvl 1
0 to 255 dB
SPL Excd Lvl 2
0 to 255 dB
Pk-1 Excd Lvl
0 to 255 dB
Pk-2 Excd Lvl
0 to 255 dB
Hysteresis
0 to 9 dB
SPL Excd Lvl 1 - (LOG, SSA)
The SPL Excd Lvl 1 sets the SPL trigger level that
exceedance records are triggered from (LOG only). You can
also view a count of the SPL events on the Stats-a display.
This count is associated with the overall measurement data
and is reset when the overall measurement is reset.
NOTE: In the SSA instrument the logic
output is asserted when it reaches this
level. See the section “Common Control
Settings” on page 7-10 for more details.
This setting can take on any value within the following
range:
SPL Excd Lvl 2 - (LOG, SSA)
The SPL Excd Lvl 2 sets a second trigger level. When the
SPL exceeds the level set by this setting, a corresponding
count is incremented once. You can view this count on the
Stats-a display. This count is associated with the overall
measurement data and is reset when the overall
measurement is reset. A special flag is set with all
exceedance records whose LMAX is greater that this level.
0 to 255dB
This setting can take on any integer value within the
following range:
0 to 255 dB
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Using ID Setting Files
7-23
PK Excd Lvl 1 - (LOG, SSA)
The Pk Excd Lvl 1 sets the trigger level for the primary peak
detector (Pk-I). When the primary peak detector level
exceeds this threshold, the corresponding Pk-I exceedance
count is incremented once. You can view this count on the
Stats-b display. This count is associated with the overall
measurement data and is reset when the overall
measurement is reset.
NOTE: The data for this comes from the
instantaneous peak level, selected by the
Weight setting.
This setting can include any integer value within the
following range:
0 to 255 dB
Pk Excd Lvl 2 - (LOG, SSA)
The Pk Excd Lvl 2 sets the trigger level for the secondary
peak detector (Pk-II). When the secondary peak detector
level exceeds this threshold, the corresponding Pk-II
exceedance count is incremented once. You can view this
count on the Stats-b display. This count is associated with
the overall measurement data and is reset when the overall
measurement is reset.
This setting can include any integer value within the
following range:
0 to 255dB
Hysteresis - (LOG, SSA)
To prevent multiple triggering/counting of the same event, a
hysteresis value may be entered. The event is triggered when
a level goes over a corresponding trigger level, but does not
become re-armed until the level drops below the value of the
trigger level minus the hysteresis value.
dB
Begin
Trigger
Hysteresis
End
Time
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This setting can include any integer value within the
following range:
0 to 9dB
LOG and SSA Wind/Tach Settings
Other transducers providing similar
pulse trains and DC voltages
representing measured parameters
could also be utilized in this manner.
For example, engine tachometers
frequently output such pulse trains
and throttle position indicators
usually output DC voltages. The
setup permits the selection of units
for both parameters which would be
consistent with this alternative to
windspeed/wind direction.
This feature is used most frequently with external weather
transducers providing an analog pulse train whose frequency
is proportional to windspeed and a DC voltage proportional
to wind direction. However, other transducers could be
utilized as explained in the left column. In the following
description, it shall be assumed that windspeed and wind
direction transducers are being used.
For the LOG instrument, these data are logged with the
Daily, Advanced Time History, Interval and Exceedance
records as selected by option settings.
For the SSA instrument, these data are logged with the
Advanced Time History and Interval records as selected by
option settings.
The Wind/Tach feature requires the
optional firmware 824-WND. If it is
not installed, attempting a setup will
display the message shown to the
right.
.
Setup of Wind/Tach Function
With either the LOG or SSA instrument active, press the S
SETUP key to access the “Edit Setup Menu”. Using the
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Using ID Setting Files
7-25
uand darrow keys, highlight the Advanced item and
select it using the r arrow key or the c Check key.
Using the uand darrow keys, highlight the Wind/Tach
item and select it using the r arrow key or the c Check
key to display the Wind/Tach menu.
7-26
Menu Items
Available Settings Options
Wind Scale
[nnn.nnn]
Wind Units
[cccc]
Direction Unit
Compass
Degrees
Percent
Volts
Number
Wind/Tach
No
Yes
Windy Threshold
[nnn.n] or [nnnnn]
Wind Excd Level
[nnn.n] or [nnnnn]
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Wind Scale
Menu Items
Available Settings Options
Windy Hysteresis
[nnn.n] or [nnnnn]
Windy Pause
Enable
No
Yes
Pulse Trigger
Voltage
0.0
2.5
Pulse Trigger
Source
Int
Ext
Wind Scale is a scale factor which provides the wind speed
(tach) when multiplied by the frequency of the wind speed
(tach) signal from the external transducer. Limits to
parameters associated with this factor are as follows:
Max. Input Freq.
Max. Display Value
Min. Input Freq.
Resolution
Min. Display Value
25000 Hz
65535 units
1 Hz
0.01 units
Examples:
Type
YOUNG Wind Sentry
YOUNG Wind Monitor
1 pulse/rev
16 pulse/rev
600 pulse/rev
Speed/Frequency
400.0 mph/235 Hz
400.0 mph/1825 Hz
30000 rpm/500 Hz
30000 rpm/8000 Hz
2500 rpm/25000 Hz
Wind Scale
1.7
0.22
60
3.75
0.10
Wind Units
Wind Units is a four character alphanumeric field (e.g. mph,
m/s, ft/s, etc.)
Direction Units
Direction Units. are used for describing Wind Direction or
Throttle Position. There are five options available.
Compass
Compass reports wind direction using the following sixteen
ordinate points: N, NNE, NE, ENE, E, ESE, SE, S, SSW,
SW, WSW, W, WNW, NW, NNW.
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Using ID Setting Files
7-27
Degrees
Degrees reports wind direction in degrees from 0 to 360º.
Percent
Percent would typically be used to report throttle position
over the range 0 to 100% as a percent of full throttle.
Voltage
Voltage reports this parameter as a DC voltage over the
range 0 to 2.49 volts.
Number
Number reports this parameter in numeric form between 0
and 255.93
Wind/Tach Enable
Note that when the Wind/Tach
feature is enabled, Ln will
automatically be enabled as well.
When this occurs, the message
“Setting Conflict” will be shown.
Select Yes to enable the Wind/Tach function. If disabled by
selecting No, Wind/Tach data will not be measured and no
corresponding data will be displayed in Views or presented
in measurement results.
Windy Threshold
“Windy” is a condition defined by wind speed above a userdefined threshold value. Since wind can influence the
propagation of sound, it is useful to note measurements
which were made during periods of higher wind levels. The
threshold level is entered as a number field using the Wind
Units defined above.
Wind Exceedance Level
The wind exceedance level represents a second threshold
level, higher than that associated with Windy. Most often
this is defined to be the wind level above which airflow over
the microphone generates pressure variations not associated
with actual acoustic signals. These pseudo-sound signals are
detected by the microphone, producing erroneous results.
The System 824 can be set to pause sampling of the sound
signal when the measured wind levels exceed this level. The
instrument will also count the number of times the wind
exceeds this level.
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824 Reference Manual
2/6/17
Windy Hysteresis
To prevent multiple triggering/counting of the same Wind
exceedance event, a hysteresis value may be entered. The
event is triggered when the wind level goes over the Wind
exceedance level, but does not become re-armed until the
level drops below the value of the exceedance level minus
the hysteresis value.
dB
Begin
Trigger
Hysteresis
End
Time
Wind Pause Enable
Select Yes to enable the Wind Pause Function. This will
cause the System 824 to pause sampling of the input signal
whenever the wind speed is above the Wind Exceedance
Level. Select No to disable this function.
Pulse Trigger Voltage
Select 0.0 V for bipolar trigger signals which are essentially
AC; triggering occurs on the zero crossing.
Select 2.5 V for unipolar trigger signals, such as those based
upon 0-5 volt logic.
Pulse Source
Generally the trigger signal for windspeed detection will be
from an external transducer connected to the 9-pin connector
labeled CONTROL. In this case, select Ext.
If Int is selected, the signal connected to the System 824
input will be used to determine the Wind/Tach level. This
setting will allow the measurement of the frequency of an
acoustic signal.
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Using ID Setting Files
7-29
LOG and SSA Time History Settings
Time History Settings are available
to both the Logging SLM (LOG) and
SLM&RTA (SSA) instruments.
The time history recording stores an LEQ, and if desired, one
or more additional user-selected measurements, such as Lpk
or Lmax. Levels can be stored rapidly, up to 32 samples per
second with the LOG instrument and 8 samples per second
with the SSA instrument. Since this function continues
storing data as long as the measurement is in progress, the
combination of a fast storage rate and a long measurement
time can consume a large amount of data memory.
Use the u and d keys to move
from one setting to the next. Then use
the r key to change the selected
setting. The l key is used to
return to previous menus.
The following tables show the Time History settings for the
LOG and SSA instruments. Each setting is described later in
greater detail.
Menu Items (LOG
Available Settings Options
instrument)
7-30
Hist Enable
No
Yes
Hist Period
1 to 255
Period Units
1/32s
1.0s
10.0s
60.0s
Other Level
None
Pk-II
Pk-I
Lmax
Advc (See Adv TH)
Resolution
0.1 dB
1.0 dB
Adv TH
Activates a set of 3 displays used to
configure what time history data
will be stored. See page 7-26.
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2/6/17
Marker Text
Marker 1
(Aircraft)
Marker 2
(Automobile)
Marker 3
(Truck)
Marker 4
(Train)
Marker 5
(Animal)
2/6/17
Menu Items
(SSA instrument)
Available Settings Options
Hist Enable
No
Yes
Hist Period
1 to 255
Period Units
1/32s
1.0s
10.0s
60.0s
Resolution
0.1 dB
1.0 dB
TH Setup
Activates a set of 3 displays used to
configure what time history data
will be stored. See “Advanced Time
History - (LOG, SSA)” on page 734.
Using ID Setting Files
7-31
Marker Text
Marker 1
(Aircraft)
Marker 2
(Automobile)
Marker 3
(Truck)
Marker 4
(Train)
Marker 5
(Animal)
Hist Enable - (LOG, SSA)
This setting provides the following two options:
No - Time history storage is disabled.
Yes - Time history storage is enabled.
Hist Period (LOG, SSA)
This setting is used in conjunction
with the “Period Units Setting”
(below).
Hist Period sets the number of history period units that
transpire between successive time history samples. These
samples continue either until the instrument is stopped or
runs out of memory. This setting can include any integer
value in the following range:
(1) to (255)
Period Units - (LOG, SSA)
Example:
Period Units selects the type of units the instrument uses to
calculate the time which transpires between successive time
history storage operations. To calculate the timer period, the
instrument multiplies the units selected in this setting by the
number set in Hist Period setting (see the previous “Hist
Period” setting and the following example).
To measure 2 samples per second, set Hist Period to 16 and Period
Units to 1/32s (16/32=1/2).
This setting provides the following four options:
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824 Reference Manual
2/6/17
When Takt functionality is enabled,
the history period will be rounded to
the nearest 5 second interval, and a
warning, “Setting Conflict”, will
appear. If the “Period Units” equal
1/32nd of a second, then the period
will be forced to a count of 160 (5
seconds).
1/32s - This sets the History Period Unit to 1/32 second intervals. Since the instrument samples the detector 32 times per second, this is the smallest resolution
time period that you can use. If you set the time history period to 1/32 second (i.e. period setting = 1 and
unit setting = Sample = 1/32s), the instrument will
store every sample it takes.
In the SSA instrument, the shortest
time history period is 1/8th of a
second. If the period is set to [1/32]
of a second the history period will be
forced to multiples of 4 to support
the maximum data rate of 8 samples
per second and the warning “Setting
Conflict” is displayed.
1.0s - This sets the history period unit to one second.
Other Level - (LOG only)
10.0s - This sets the history period unit to ten seconds.
60.0s - This sets the history period unit to sixty seconds.
Use the Other Level setting to select the second
measurement level stored in each time history record along
with the Leq. This setting provides the following options:
None - The instrument stores the Leq but does not
store a second level.
Pk-I - The second level the instrument stores is the
greatest instantaneous level (Lpk) detected by the primary peak detector that occurred during the time history period. The primary peak level is weighted
according to the state of the Pk Weighting setting.
Pk - II - The second level the instrument stores is the
greatest instantaneous level (Lpk) detected by the secondary peak detector that has occurred during the
time history period. The secondary peak level is
weighted according to the state of the Weighting setting.
Lmax - The second level the instrument stores is the
maximum level (Lmax) that has occurred during the
time history period.
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Using ID Setting Files
7-33
The “Any Data” information stored
with the Time History is accessed
through the Time History menu
under the “View” key.
Resolution - (LOG, SSA)
Advc - Stores up to 38 different parameters with each
time history period which are user selectable, such as:
Leq, Peak, Max, Min, Takt maximal, battery voltage
and temperature. See Advanced Time History screens
below.
In order to double the time history storage capacity, it is
possible to reduce the resolution of the Time History record
from 0.1dB to 1.0dB.
0.1dB - Leq and the optional Other Level are stored
with the highest resolution (0.1dB) which requires 2
bytes of memory per level.
1.0dB - Leq and the optional Other Level are stored
with 1.0dB resolution which requires only 1 byte per
level stored. Levels are rounded to the nearest integer
(85.5 would be stored as 86dB and 85.4 would be
stored as 85dB).
Advanced Time History - (LOG,
SSA)
Up to 40 different parameters can be stored (LOG and SSA)
with each time history period including Wind/Tach data and
spectral data (SSA only). These are all user selectable in the
Advanced Time History displays.
The Advanced Time History displays are shown below:
SSA & LOG
SSA only if Takt is ON
SSA only if Takt is OFF
LOG only with Takt OFF
NOTE: RTA Leq and RTA Live are
mutually exclusive, allowing you to
choose only one for each time history
period. (SSA only)
7-34
SSA & LOG
LOG only with Takt ON
Once the Advanced Time History displays have been
selected, do the following to navigate through and setup
each display.
824 Reference Manual
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NOTE: If Spectral Ln is set to
[Interval] and Interval Ln’s is
enabled and the Interval Period is
00:00:00 then the Interval Period is
set to 00:00:01 (one second) and the
warning “Setting Conflict” is
displayed.
Marker Text - (LOG, SSA)
•
Use the up uand down d and left land right
rarrow keys to move the cursor between each selection or check box.
•
The Check c key toggles the selection on or off. The
Reset key R will uncheck all the items on the current
display.
•
To move to the next screen, (a, b, or c), highlight “Next”
and press the Check c key.
•
When all of your selections have been made, highlight
“Done” and press the Check c key.
One of the features of the 824 is the ability to mark or
annotate the SLM Time History as the instrument is running.
This allows the user to identify each noise source as the
measurement is being taken. There are 5 Markers and each
marker can be assigned an 8 character description. See page
7-55 for a description of the Marker display.
LOG and SSA Interval Settings
Interval Settings are available on the
LOG and SSA instruments.
2/6/17
The Intervals menu sets the System 824 to automatically
store at regular time periods, Leq, SEL, Lmax, Lmin, LpkI,
LpkII, and the six Ln levels. The Interval time period can
range from one second to nearly one hundred hours. The
Interval feature is particularly useful when monitoring noise
levels for extended periods of time because you can
determine how the statistical makeup of the acoustic
environment has changed over time.
Using ID Setting Files
7-35
The u and d keys move from
one setting to the next. The r key
changes the selected setting. The
l key is used to return to previous
menus.
The following table shows the
available Intervals settings. Each
setting is described later in greater
detail.
T
Menu Items
Available Settings Options
Intv Enable
No
Yes
Intv Period
hh:mm:ss
Intv Time Sync
No
Yes
Intv Save Ln’s
No
Yes
Intv Auto Stop
No
Yes
Intv Threshold
0 to 255
Intv Exchange
3dB
4dB
5dB
6dB
Intv Spectrum
(SSA only)
None
@Max
Mins
To store interval spectral Ln levels,
set “Spectral Ln” to “Interval”,
enable Ln and Interval histories and
set “Intv Save Ln” to “Yes”.
Intv Enable - (LOG, SSA)
Intv Enable enables or disables the automatic storage of
interval statistical records.
This setting provides the following two options:
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No - Disables interval storage.
Yes - Enables interval storage.
NOTE: If Intervals are enabled and Interval Ln’s are enabled
and Ln’s are not enabled then Ln’s are turned on and the
warning “Setting Conflict” is displayed.
Intv Period - (LOG, SSA)
NOTE: If set to 00:00:00 then the period
is 0.125 seconds for SSA and infinite for
LOG.
Intv Time Sync - (LOG, SSA)
Intv Period sets the time interval between successive
interval storage operations. These storage operations
continue either until the instrument is stopped or runs out of
memory. You can set this to any time value in the following
range:
00:00:01 to 99:59:59 (i.e. one second to 99 hours,
59 minutes and 59 seconds)
Intv Time Sync setting either enables or disables the time
interval sync feature. When enabled, this feature causes the
Interval history storage operations to be synchronized with
the real-time of day clock. This synchronization can occur
on a 1, 5, 10, 15, 20, 30, or 60 minute basis. The Intv Period
setting should also be set accordingly so that the
synchronization works properly. When you start a
measurement, the initial storage interval will last for only a
fraction of the determined synchronization until the start of
the next time segment; at which time a new, synchronized
storage interval will begin.
This setting provides the following two options:
No - Disables interval synchronization.
Yes - Enables interval synchronization.
Intv Save Ln’s - (LOG, SSA)
Intv Save Ln’s either enables or disables the automatic
storage of the six LN percentile levels in the interval record.
This setting provides the following two options:
No - The six LN levels are not stored with the interval
record.
Yes - The six LN levels are stored with the intervalrecord.
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Using ID Setting Files
7-37
NOTE: If Intervals are enabled and Interval Ln’s are enabled
and Ln’s are not enabled then Ln’s are turned on and the
warning “Setting Conflict” is displayed.
Intv Auto Stop - (LOG, SSA)
NOTE: Do not use this feature with the
Time Sync feature, or you will not get the
full time period you desire.
Use the Intv Auto Stop setting to enable or disable the autostop feature. When enabled, this feature causes the
instrument to automatically stop the measurement at the end
of each storage interval. This allows you to precisely time a
series of manual measurements. To start a new measurement
after an automatic stop, just press the s Run/Stop key.
This setting provides the following two options:
No - Disables the automatic stop feature.
Yes - Enables the automatic stop feature.
Intv Threshold - (LOG, SSA)
Intv Threshold sets the threshold for computing the interval
time weighted average (TWA). As per the requirements of
various regulatory agencies, only those sound levels which
are above a certain threshold level are used when computing
the TWA. Accordingly, this setting can take on any integral
value within the following range:
0 to 255 dB
For hearing conservation measurements, set the threshold to
80dB. For most community noise measurements, set the
threshold to 0dB.
Intv Exchange - (LOG, SSA)
The Intv Exchange sets the exchange rate (sometimes called
the “doubling rate”) that is used to calculate the interval
TWA. The exchange rate reflects the relationship between
the permitted exposure levels and the exposure duration.
Selecting an exchange rate of 5dB, for example, means that
5dB may be added to the permissible exposure level every
time the exposure duration is cut in half. This setting
provides the following four options:
3dB - The 3dB (default) option is the most commonly used and results in the Leq time weighted average which is used in Europe and for measurements
that comply with U.S. Environmental Protection
Agency (EPA) regulations.
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4dB - The 4dB option results in the LDOD time
weighted average which is used for measurements
that comply with U.S. Department of Defense (DOD)
regulations.
5dB - The 5dB option results in the LOSHA time
weighted average which is used for measurements
that comply with U.S. Occupational Safety and
Health Administration (OSHA) regulations.
6dB - The 6dB option results in the LAvg time
weighted average which is merely a convenient representation of the long-term average noise level as
opposed to the RMS noise level.
Intv Spectrum - (SSA only)
The Intv Spectrum allows you the choice of storing spectral
data with the interval. It will always give you the Leq
spectra and one other spectra. This setting provides the
following three options:
None - Does not store any spectral data besides the
Leq spectra with the interval.
@Max - Stores the spectra associated with the maximum broadband level during the interval period.
Min - Stores the minimum level obtained by each filter. This is a bin by bin minimum level.
Logging SLM Exceedance History Settings
Exceedance History Settings are
only available to the Logging SLM
(LOG) instrument.
Exceedance History settings allow you to select what data
will be saved in memory during an exceedance. An
exceedance is defined as an acoustic event characterized by
the instantaneous rms sound pressure level or peak level
(Pk-1 or Pk-2) going above or exceeding a predetermined
level. For further detail see the section “LOG and SSA
Triggering Settings” on page 7-22.
Triggering - (LOG)
The Triggering menu defines event triggering used to initiate
an exceedance or event. See “Logging SLM Triggering
Setting” earlier in this chapter.
2/6/17
Using ID Setting Files
7-39
Excd Enable - (LOG)
The Excd Enable setting allows you determine whether or
not exceedance data will be stored in memory when
exceedance trigger conditions are met. This setting provides
the following two options:
Yes - Exceedance data will be stored in memory when
exceedance conditions are met.
- Exceedance data will not be measured or stored
in memory when exceedance conditions are met.
No
Min Duration - (LOG)
The Min Duration setting allows you to determine the
minimum number of seconds an exceedance must last for it
to be logged. This setting can take on any time value in the
following range:
0-255 second
Excd Time Hist - (LOG)
T.H. Period - (LOG)
The Excd Time Hist setting enables you to indicate whether
or not to have an Exceedance Time History saved as part of
the exceedance. This setting provides the following two
options:
Yes
- The Exceedance Time History will be saved.
No
- The Exceedance Time History will not be saved.
The T.H. Period setting allows you to set the period of time
for the Leq stored in the Exceedance Time History, in steps
of 1/32 seconds. This setting can take on any time value in
the following range:
1/32 - 32/32 seconds
Excd Trigger - (LOG)
The Excd Trigger setting enables you to select whether the
Exceedance Trigger utilizes the fixed trigger levels or uses a
special 10 dB rise then fall Passby trigger. This setting
provides the following two options:
Level
Note: Minimum duration is not
considered
when
using
the
Exceedance Trigger in Passby
Mode.
7-40
- Enables fixed level triggering.
PassBy
- Enables 10 dB Passby triggering.
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Excd Time - (LOG)
Using the symmetry data provided
with every exceedance it is possible
to calculate the time of the Max even
though you choose to record the start
time of the event.
The Excd Time setting allows you to select whether the time
reported for the exceedance is the time that it started or the
time of the maximum level. This setting provides the
following two options:
- The exceedance time will be logged at the
beginning of the exceedance event.
Start
Max - The exceedance time will
be logged at the maximum level of the exceedance event.
Timed Excd Period - (LOG)
This setting will extend an event to be at least as long as the
time set (mm:ss) if it is over the threshold for at least the
minimum duration.
NOTE: This setting is only available through the serial port.
using the command S76, see table “Setting Commands” on
page A-25Logging SLM Daily History Settings
Daily History Settings are only
available to the Logging SLM (LOG)
instrument.
Use the u and d keys to move
from one setting to the next. Then use
the r key to change the selected
setting. The l key is used to
return to previous menus.
Daily Enable - (LOG)
2/6/17
The Model 824 automatically calculates daily sound
statistics including: Leq 24, Ldn, CNEL, Lpeak, Luwpk, Ln’s,
Lmax, and Lmin; and for each hour of the day the hourly Leq,
the hourly EXCD Leq and the resultant Background Leq.
Menu Items
Available Settings Options
Daily Enable
Yes
No
Daily Ln’s
Yes
No
Daily Enable allows you to store daily data such as listed
above. This setting provides the following two options.
Yes
- Storage of daily history data will occur.
No
- Daily data will not be stored.
Using ID Setting Files
7-41
Daily Ln’s - (LOG)
Daily Ln’s allows you to store six Ln percentiles with the
Daily History data. This setting provides the following
options:
- Storage of daily data for Ln’s percentile will
occur.
Yes
No - Daily Data will not be stored for the Ln’s percentiles.
Logging SLM Define Report Settings
Define Report Settings are also
available to the SSA instrument. For
more details on Reporting, see
“Printing a Report” on page 8-1
Define Report allows you to determine which individual
reports will be included in the “Tailored” report. This allows
you to tailor the measurements and the reports desired to
your requirements.
Use the u and d keys to move
from one setting to the next. Then use
the r key to change the selected
setting. The l key is used to
return to previous menus.
The following is a table of the Define Report settings. Each
setting is described later in greater detail.
7-42
Menu Items
Available Settings
Options
Data Report
No
Yes
Setup Report
No
Yes
SPL Histogram
No
Yes
Pk-1 Histogram
No
Yes
Pk-2 Histogram
No
Yes
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Data Report - (LOG, SSA)
Intv Report
No
Short
Long
Hist Report
No
Yes
The Data Report setting either enables or disables the
printing of the data report. The data report contains all the
basic measurement parameters for both the overall and
current measurements. This setting provides the following
two options:
No - The data report will not print.
Yes - The data report will print.
Setup Report - (LOG, SSA)
The Setup Report setting either enables or disables the
printing of the setup report. The setup report shows each of
the parameters and how they are set. This setting provides
the following two options:
No - The data report will not print.
Yes - The data report will print.
SPL Histogram - (LOG)
SPL Histogram either enables or disables the printing of the
SPL histogram report. The histogram report contains a
histogram of the SPL levels that have occurred during the
overall and current measurements. The report also prints a
table of all (1 to 99%) LN percentiles. This setting provides
the following two options:
No - The SPL histogram report will not print.
Yes - The SPL histogram report will print.
Pk-1 Histogram - (LOG)
The Pk-1 Histogram setting either enables or disables the
printing of the Peak I histogram report. The histogram report
contains a histogram of the Peak I levels that have occurred
during the overall measurement. This setting provides the
following two options:
No - The peak I histogram report will not print.
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Using ID Setting Files
7-43
Yes - The peak I histogram report will print.
Pk-2 Histogram - (LOG)
The Pk-2 Histogram either enables or disables the printing
of the Peak 2 histogram report. The histogram report
contains a histogram of the Peak 2 levels that have occurred
during the overall measurement. This setting provides the
following two options:
No - The peak 2 histogram report will not print.
Yes - The peak 2 histogram report will print.
Intv Report - (LOG, SSA)
The Intv Report either disables the printing of the interval
report or enables either the “long” or the “short” version of
this report. The “short” interval report contains all the basic
measurement parameters for each interval period in a
specified range of records. The “long” interval report
contains everything the short report contains plus some
additional information.
This setting provides the following three options:
No - The interval report will not print.
Short - The “short” interval report (including Lmax,
Lmin, SEL, Leq, Pk-I, Pk-II, overloads, and exceedances) will print.
Long - The “long” interval report (including Lmax,
Lmin, SEL, Leq, Pk-I, Pk-II, overloads, exceedances,
and six Ln Percentiles) will print.
Hist Report - (LOG, SSA)
The Hist Report either enables or disables the printing of the
Time history report. The history report contains the Leq, and
optionally one selectable level (Lpk-I, Lpk-II, or Lmax)
basic measurement parameter for each time history period.
This setting provides the following two options:
No - The history report will not print.
Yes - The history report will print.
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Menu Layout of SSA Settings
The SLM&RTA Edit Settings menu has 49 configurable
items. Provided in this section is a table depicting the menu
layout of the SLM&RTA instrument’s Settings.
Menu Items
Submenu
Title
SLM
RTA
2/6/17
Available Settings Options
User customized text entry
Detector
Slow
Fast
Impl
Weighting
A
C
FLT
Gain
A
C
FLT
Transducer
Condnsr
Elctret
Direct
Random Corr
No
Yes
Pk Weighting
A
C
FLT
RTA Detector
Slow
Fast
RTA Weighting
A
C
FLT
Bandwidth
1/1
1/3
Using ID Setting Files
7-45
Intervals
7-46
Intv Enable
No
Yes
Intv Period
hh:mm:ss
Intv Time Sync
No
Yes
Intv Save Ln’s
No
Yes
Intv Auto Stop
No
Yes
Intv Threshold
0 - 255 dB
Intv Exchange
3dB
4dB
5dB
6dB
Intv Spectrum
None
@Max
Min
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Time History
Ln
2/6/17
Hist Enable
No
Yes
Hist Period
0 - 255 (default: 60)
Period Units
1/32s
1.0s
10.0s
60.0s
Resolution
0.1db
1.0db
TH Setup
Activates a set of 3 displays used
to configure what time history data
will be stored. See the section
“Advanced Time History - (LOG,
SSA)” on page 7-34.
Marker Text
Marker 1 (Aircraft)
Marker 2 (Automobile)
Marker 3 (Truck)
Marker 4 (Train)
Marker 5 (Animal)
Enable
No
Yes
Start Level
0-99dB (default 15dB)
Ln 1 Percent
Selectable (default: 1.67%)
Ln 2 Percent
Selectable (default: 8.33%)
Ln 3 Percent
Selectable (default: 33.33%)
Ln 4 Percent
Selectable (default: 50%)
Ln 5 Percent
Selectable (default: 66.67%)
Ln 6 Percent
Selectable (default: 90%)
Spectral LN
None
Overall
Interval
Using ID Setting Files
7-47
Triggering
Advanced
SPL Excd Lvl 1
0 - 255 dB (default: 115dB)
SPL Excd Lvl 2
0 - 255 dB (default: 120dB)
Pk-1 Excd Lvl
0 - 255 dB (default: 140dB)
Pk-2 Excd Lvl
0 - 255 dB (default: 140dB)
Hysteresis
0 - 9 dB (default: 2dB)
See “Advanced Menu Layout” on page 7-54
Menu Layout of Integrating SLM (ISM) Settings
The Integrating SLM (ISM) Edit Settings menu has 16
configurable items. Provided in this section is a table
depicting the menu layout of the ISM instrument’s Standard
Settings.
ISM Setting
Menu
Items
Submenu
Title
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824 Reference Manual
Available Settings
Options
User customized text
entry
2/6/17
SLM
Advanced
2/6/17
Detector
Slow
Fast
Impl
Weighting
A
C
FLT
Range
Normal
Low
High
Transducer
Condnsr
Elctret
Direct
Random Corr
No
Yes
Pk Weighting
A
C
FLT
Crnt Exchange
3dB
4dB
5dB
6dB
Crnt Threshold
0 - 255 dB
See “Advanced Menu Layout” on page 7-54
Using ID Setting Files
7-49
Menu Layout of Logging SLM Settings
The Logging SLM (LOG) Edit Settings menu has 66
configurable items. Provided in this section is a table
depicting the menu layout of the LOG instrument’s Standard
Settings.
LOG Settings
Menu Items
Submenu
Title
SLM
7-50
Available Settings Options
User customized text entry
Detector
Slow
Fast
Impl
Weighting
A
C
FLT
Range
Normal
Low
High
Transducer
Condnsr
Elctret
Direct
Random Corr
No
Yes
Pk Weighting
A
C
FLT
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TWA
Ln
Triggering
2/6/17
Ovll Exchange
3dB
4dB
5dB
6dB
Ovll Threshold
0 - 255 dB (default: 80dB)
Ovll Criterion
0 - 255 dB (default: 90dB)
Criterion Time
0 - 99 hours (default: 8 hours)
Crnt Exchange
3dB
4dB
5dB
6dB
Crnt Threshold
0 - 255 dB (default: 80dB)
Crnt Criterion
0 - 255 dB (default: 90dB)
Start Level
0 - 99dB (default 15dB)
Ln 1 Percent
Selectable (default: 1.67%)
Ln 2 Percent
Selectable (default: 8.33%)
Ln 3 Percent
Selectable (default: 33.33%)
Ln 4 Percent
Selectable (default: 50%
Ln 5 Percent
Selectable (default: 66.67%)
Ln 6 Percent
Selectable (default: 90%)
SPL Excd Lvl 1
0 - 255 dB (default: 115dB)
SPL Excd Lvl 2
0 - 255 dB (default: 120dB)
PK-1 Excd Lvl
0 - 255 dB (default: 140dB)
PK-2 Excd Lvl
0 - 255 dB (default: 140dB)
Hysteresis
0 - 9 dB (default: 2dB)
Using ID Setting Files
7-51
Time History
7-52
Hist Enable
Yes (default)
No
Hist Period
0 - 255 (default: 60)
Period Units
1/32s
1s (default)
10s
60s
Other Level
None (default)
Pk-II
Pk-I
Lmax
Advc
Resolution
0.1dB (default)
1.0dB
Adv TH
Activates a set of 3 displays used
to configure what type of time
history data will be stored. See
“Advanced Time History - (LOG,
SSA)” on page 7-34.
Marker Text
Marker 1 (Aircraft)
Marker 2 (Automobile)
Marker 3 (Truck)
Marker 4 (Train)
Marker 5 (Animal)
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Intervals
Excd History
2/6/17
Intv Enable
Yes (default)
No
Intv Period
0-24:0-60:0-60 (hh:mm:ss)
Intv Time Sync
Yes (default)
No
Intv Save Ln’s
Yes (default)
No
Intv Auto Stop
Yes
No (default)
Intv Threshold
0 - 255 dB
Intv Exchange
3dB (default)
4dB
5dB
6dB
Triggering
SPL Excd Lvl 1
SPL Excd Lvl 2
PK-1 Excd Lvl
PK-2 Excd Lvl
Hysteresis
Excd Enable
Yes
No (default)
Min Duration
0 - 999 seconds
Excd Time-Hist
Yes
No (default)
T.H. Period
0 - 255 seconds 9 multiplied by
1/32s
Excd Trigger
Level
PassBy
Excd Time
Start
Max
Using ID Setting Files
7-53
Daily
History
Daily Enable
Yes
No (default)
Daily Ln’s
Yes
No (default)
Define
Report
Data Report
Yes (default)
No
Advanced
See Advanced Menu (below)
Advanced Menu Layout
7-54
Menu
Items
Submenu
Available Settings
Options
Controls
(See also
“Control
Settings _(SSA,
LOG)” on page
7-10)
AC/DC Output
AC-1 AC-2
AC-1 DC
AC-2 DC
AC-2 AC-1
Logic-In Mode
None
Pause
Toggle
Level
Alarm
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Menu
Items
Submenu
Available Settings
Options
Controls
(Continued)
Logic-Out
Off
RMS
Peak
R+P
Intv
R+I
P+I
R+P+I
A:D
R+A
P+A
R+P+A
I+A
R+I+A
P+I+A
R+P+I+A
R/S
Excd
Logic-Out Time
0 - 255 sec
Logic-Out #2
Off
RMS
Peak
R+P
Intv
R+I
P+I
R+P+I
A:D
R+A
P+A
R+P+A
I+A
R+I+A
P+I+A
R+P+I+A
R/S
Excd
Logic-Out #2 Time
0 - 255 sec
Using ID Setting Files
7-55
Menu
Items
Submenu
Available Settings
Options
Controls
(Continued)
Heater On
No
Yes
E. A. Cal Tone
No
Yes
Wind/Tach
Wind Scale
0.015 - 255.99
(See also “LOG
and SSA Wind/
Tach Settings”
on page 7-25)
Wind Units
4 alphanumeric characters
Direction Units
Compass; 16 ordinates
Degrees; 0 -360
Percent; 0 - 100
Volts: 0 - 2.49
Number; 0 - 255.93
Wind/Tach
No
Yes
Windy Threshold
Level
0.0 - 65,535
Windy Exceedance
Level
0.0 - 65,535
Windy Hystereses
0.0 - 65,535
Windy Pause Enable
No
Yes
Pulse Trigger Voltage
0.0
2.5
Pulse Source
Int
Ext
Data Report
No
Yes
Setup Report
No
Yes
This is an
optional feature
requiring the
firmware 824WND
Define Report
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Menu
Items
Submenu
Available Settings
Options
Define Report
(Continued)
SPL Histogram
No
Yes
Pk-I Histogram
No
Yes
Pk-II Histogram
No
Yes
Interval Report
No
Short
Long
History Report
No
Yes
Exceedance Report
No
Short
Long
Daily Report
No
Short
Long
Check Menus
In addition to being able to modify an instrument ID’s
settings through the Edit Settings item in the Setup menu,
selected settings can also be modified through what is
known as a Check menu which is specific to the current
display function. The Check menu is accessed simply by
pressing the c Check key from within the System 824’s
different views.
The available Check menu options vary between an
instrument ID’s different views. The options available from
each display allows the user to change settings peculiar to
that display function. In many cases they are shortcuts to
other displays. In some cases the check menu allows you to
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Using ID Setting Files
7-57
toggle between a views tabular mode or graphical spectrum
mode.
This section will present the following:
•
Check Menu Example
•
SLM Check Menu Options
•
Other SSA Check Menus
•
Other Logging (LOG) Check Menus
Check Menu Example
The Check menu is accessed by simply pressing the c
Check key from within an Instrument ID’s view. The
following is an example of using the Check menu from a
SLM view to change the Detector setting from the selected
instrument’s SLM display:
Use the u and d keys to move
from one setting to the next. Then use
the r key to change the selected
setting. The l key is used to
return to previous menus
7-58
Step 1
From the Instrument’s SLM (LOG or SSA) view
display, press the c key to access the Check
menu. A menu similar to the following appears:
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Step 2
Use the u and d arrow keys to highlight Settings, then press the c Check key or ther
arrow key. A menu similar to the following
appears:
Step 3
Use the u and d arrow keys to highlight
SLM, then press the c Check key or the r
arrow key. A menu similar to the following
appears:
Step 4
Use the u and d arrow keys to highlight
Weighting, then press the c Check key or the
r arrow key. A menu similar to the following
appears:
Step 5
Highlight the desired weighting and press the c
Check key.
Using ID Setting Files
7-59
SLM Check Menu Options (SSA and LOG)
The SLM display check menus for the SSA and LOG
The Check menu’s Controls and
instruments are identical. The following describes the Check
Settings items correspond to those
Pressingearlier
the right
rSettings
arrow key Menu setting.
described
in the
takes yousection
to a different
place than
descriptions
of this chapter.
pressing the check c key. See
Menu Items
Purpose
example below:
Mark
Puts a marker in the time history
Settings
Modifies the SLM settings for the
selected instrument
Graph
Changes the scaling of the
instrument’s SLM history graph
A box with an arrow next to a menu
Controls
Modifies the Control menu for the
item indicates that you use the right
selected instrument
rarrow key to access another display
or menu. The check c key takes you
to a different place. An empty box The following screen appears when accessing the Check
indicates that a check c takes you menu from the SLM view.
to the same place as the right
rarrow key.
Mark Display
7-60
Pressing the right rarrow key when “Mark” is
highlighted puts you in the “Mark” display. The following
screen appears:
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The “Mark” display shows the current SPL level and a time
history of the SPL level is shown graphically. This enables
you to set a marker in the time history. To set a marker in the
time history, press the Check c key. The following menu
appears:
When “Set Mark” is initiated by
pressing the Check c key, a marker
is placed into the time history record
at that point in time.
With “Set Mark” highlighted, press the Check
place a marker in the time history.
c key to
The Settings menu item in the “Mark” Check menu allows
you to access the “Settings” menu in the marker area in
order to change the marker descriptions.
The Graph menu item allows you to change the scaling of
the Mark graph. (See below)
Graph Menu
Graph Level may also be changed
interactively with the Adjust Graph
display (below).
There are two Graph settings available:
Menu Items
Available Settings Options
Graph Level
-39 to 799
Graph Scale
2, 1, 1/2, 1/4, 1/8
The Graph Level setting allow you to change the base level
of the SPL history graph. The following is the possible
setting range:
-39 to 799
The Graph Scale setting allows you to change the vertical
range of the SPL history graph, using the following possible
settings:
2, 1, 1/2, 1/4, 1/8 dB per dot (pixel)
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Using ID Setting Files
7-61
Pressing therarrow key on the Graph menu item allows
you to adjust the graph settings through a menu. A screen
similar to the following appears:
The u or d key allows you to
adjust the Graph Level. The l or
r key allows you to adjust the
Graph Scale. When you are finished
customizing the settings of the
graph, press the c key to finish.
Pressing the c key on Graph menu item (from the SLM
Check menu) allows you to graphically and interactively
adjust the Graph settings. A screen similar to the followings
appears:
Settings
The Settings menu allows you access to the SLM settings
area that is usually accessed from the SETUP S key. (This
is a shortcut to the SLM settings so you can modify the items
in the SLM menu)
NOTE: Refer to the Settings Description
section and the individual instrument’s
Settings Menu Layout sections for details
on the configuration options for this
menu.
Controls Settings Menu
7-62
Allows you access to the Settings menu in the Controls area
that is usually accessed from the SETUP S key. (This is a
shortcut to the Controls settings so you can modify the items
in the Controls menu)
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Other SSA Check Menus
NOTE: The SSA “Any Data” check
menu is the same for the LOG
instrument.
This section will present the Check menu screens that
display when pressing c Check key from within the
System 824 SSA instrument definition.
Any Data Check Menu
The following Check menu is accessible from the “Any
Data” screen. Press the Check c key and the following
appears:
Following is a chart of the check menu with a description of
each menu item:
RTA Check Menu
2/6/17
Menu Items
Purpose
Mark
Puts a marker in the time history.
Settings
Modifies the SLM settings for the
selected instrument.
The following Check menus are accessible from the RTA
Live, RTA Leq, RTA Max and RTA Min views:
Using ID Setting Files
7-63
Following is a chart of the check menu with a description of
each menu item:
Intervals Check Menu
Menu Items
Purpose
Tabular/
Spectrum
Enables
switching
between
spectrum (graphical) view and
Tabular view.
Settings
Modifies the SLM settings for the
selected instrument.
Graph
Changes the scaling of the
instrument’s SLM history graph
Bandwidth
Selects either 1/1 or 1/3 octave
filters.
The intervals displays have three different check menus
depending upon which display you are viewing.
When viewing the displays Interval-a through Interval-e the
following menu appears after pressing the Check c key:
Following is a chart of the check menu with a description of
each menu item:
7-64
Menu Items
Purpose
Leq Spectrum
Allows you to view the Leq spectral
data
Max/Min
Spectra
Allows you to view the Max or Min
spectral data
Ln Spectrum
Allows you to view the Spectral Ln
data
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Locate
Locates a specific interval record
Settings
Modifies the interval settings
In the “Leq Spectrum” display press the Check
the following menu appears:
c key and
Following is a chart of the “Leq Spectrum” check menu with
a description of each menu item:
Time History Check Menu
2/6/17
Menu Items
Purpose
ByTime
Allows you to view the Leq for each
interval over time
Intv Data
Allows you to view the Interval-a
through Interval-e displays
Max/Min Spectra
Allows you to view the Max or Min
spectral data
Ln Spectrum
Allows you to view the Spectral Ln
data
Locate
Locates a specific interval record
Settings
Modifies the interval settings
Graph
Changes the scaling of the “Leq
Specta” graph
Bandwidth
Changes the filters to either 1/1 or
1/3 octave
Press the Check c key while viewing either of the Time
History displays and the following check menus appear:
Using ID Setting Files
7-65
Following is a chart of the Time History check menu with a
description of each menu item:
Run Log Check Menu
7-66
Menu Items
Purpose
Broadband/
Spectrum
Allows you to view the broadband
history graph or the spectral data
Locate
Locates a specific time history
record
Settings
Modifies the time history settings
Graph
Changes the scaling of the
instrument’s time history graph.
Press the Check c key while viewing the Run Log display
and the following check menu appears:
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Following is a chart of the Run Log check menu with a
description of each menu item:
Ln Centiles Check Menus
Menu Items
Purpose
First
Locates the first Run Log record
Last
Locates the last Run Log record
Find
Finds the specified Run Log record
Locate T.H.
Displays the Time History
There are three different Check menus contained within the
Ln Centiles views.
Press the Check c key while viewing the Ln Centile’s
broadband displays and the following check menu appears:
Following is a chart of the Ln Centiles broadband check
menu with a description of each menu item:
2/6/17
Menu Items
Purpose
Enable Ln
Enables or disables Ln data
Start Level
Sets the minimum dB level to be
calculated in the Ln data
Ln 1 Percent
Changes the percentage for Ln 1
Ln 2 Percent
Changes the percentage for Ln 2
Ln 3 Percent
Changes the percentage for Ln 3
Ln 4 Percent
Changes the percentage for Ln 4
Using ID Setting Files
7-67
Ln 5 Percent
Changes the percentage for Ln 5
Ln 6 Percent
Changes the percentage for Ln 6
Spectral LN
None
Overall
Interval
Press the Check c key while viewing the Ln Centile’s
spectral displays and the following check menu appears:
Following is a chart of the Ln Centiles spectral check menu
with a description of each menu item:
Menu Items
Purpose
Start Level
Sets the minimum dB level to be
calculated in the Ln data
Ln 1 Percent
Changes the percentage for Ln 1
Ln 2 Percent
Changes the percentage for Ln 2
Ln 3 Percent
Changes the percentage for Ln 3
Ln 4 Percent
Changes the percentage for Ln 4
Ln 5 Percent
Changes the percentage for Ln 5
Ln 6 Percent
Changes the percentage for Ln 6
Press the Check c key while viewing the Ln Centile’s
spectrum displays and the following check menu appears:
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Menu Items
Purpose
Settings
Modifies the spectral Ln settings.
(See table above, “spectral check
menu items”, for a description of the
settings)
Graph
Changes the scaling of the
instrument’s spectrum graph.
Other Logging (LOG) Check Menus
See “SLM Check Menu Options
(SSA and LOG)” on page 7-60 for a
description of the (LOG) SLM check
menu.
This section presents the LOG instrument’s available Check
menus that are in addition to the SLM Check menu
previously described in this chapter.
Any Data Check Menu
See “Any Data Check Menu” on page 7-69 for a description.
2/6/17
Using ID Setting Files
7-69
Current SLM / Overall SLM
Check Menu
Exposure Check Menu
7-70
Current SLM and Overall SLM views have access to the
following Check menu:
Menu Items
Purpose
Mark
Puts a marker in the time history
record if the check c key is pressed.
If the right rarrow key is pressed it
puts you in the Marker screen.
Settings
Modifies the SLM settings for the
selected instrument.
Graph
Changes the scaling of the
instrument’s SLM history graph.
TWA
Modifies the TWA settings for the
selected instrument.
The Exposure view has access to the following Check
menu:
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LN Centiles Check Menu
Stats Check Menu
2/6/17
Menu Items
Purpose
Ovll Exchange
Sets the exchange rate that is used to
calculate the overall TWA.
Ovll Threshold
Sets the threshold for computing the
overall time weighted average
(TWA)
Ovll Criterion
Sets the TWA level which
constitutes 100% dose for the
overall measurement.
Criterion Time
Sets how long of an exposure time
for the TWA level you can have
before 100% dose occurs for the
overall measurement.
The Ln Centile view has access to the following Check
menu:
Menu Items
Purpose
Settings
Modifies the Ln percentiles settings
for the selected instrument.
Graph
Changes the scaling of the
instrument’s Ln-b Centiles graph
The Stats view has access to the following Check menu:
Using ID Setting Files
7-71
Menu Items
Purpose
SPL Excd Lvl 1
Sets the lowest SPL trigger level.
SPL Excd Lvl 2
Set the higher trigger level.
Pk-1 Excd Lvl
Sets the trigger level for the primary
peak detector (i.e. Pk-I).
Pk-2 Excd Lvl
Sets the trigger level for the
secondary peak detector (i.e. Pk-II).
Hysteresis
Sets a hysteresis value to prevent
multiple triggering/counting of the
same event
Run Log Check Menu
See “Run Log Check Menu” on page 7-72 for a description
of the Run Log check menu for the LOG instrument.
Time History Check Menu
The Time History view has access to the following Check
menu:
7-72
Menu Items
Purpose
Mark
Puts a marker in the time history
record
Locate
Allows you to locate a time history
record
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Intervals Check Menu
Excd History Check Menu
Settings
Modifies the Time History Settings.
Graph
Adjusts the scaling of the Time
History graph
The Intervals view has access to the following Check menu:
Menu Items
Purpose
Locate
Locates an interval record
Settings
Modifies the Interval Settings.
The Excd History displays have two different check menus
depending upon which display you are viewing.
When viewing the displays Excd-a through Excd-b the
following menu appears after pressing the Check c key:
Following is a chart of the check menu with a description of
each menu item:
2/6/17
Using ID Setting Files
7-73
Menu Items
Purpose
Time History
Displays the Excd time history
graph
Locate
Locates
record
Settings
Modifies the Exceedance settings
a
specific
Exceedance
In the “Excd Time History” display press the Check c key
and the following menu appears:
Following is a chart of the “Excd Time History” check menu
with a description of each menu item:
Daily History Check Menu
Menu Items
Purpose
Excd Data
View Excd-a and Excd-b displays
Locate
Locates
record
Settings
Modifies the Exceedance settings
Graph
Adjusts the scaling of the Excd
Time History graph
a
specific
Exceedance
The Daily History display has two different check menus,
one for the Daily data and one for the Hourly data.
When viewing the Daily History the following menu
appears after pressing the Check c key:
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Following is a chart of the “Daily History” check menu with
a description of each menu item:
Menu Items
Purpose
Hourly Data
Displays hourly data
First
Displays the first hourly record
Last
Displays the last hourly record
Find
Displays a specific record
Settings
Modifies the Daily History settings
In the “Hourly” display press the Check
following menu appears:
c key and the
Following is a chart of the “Hourly History” check menu
with a description of each menu item:
2/6/17
Menu Items
Purpose
Daily Data
Displays Daily data
First
Displays the first hourly record
Last
Displays the last hourly record
Using ID Setting Files
7-75
Find
Displays a specific record
Settings
Modifies the Daily History settings
Graph
Adjusts the scaling of the Hourly
Leq graph
NOTE: Check menus are not available
for the Metrics, PassBy, and Wind /
Tach views.
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CHAPTER
8
Printing a Report
The System 824 allows you to print a report from data collected during a measurement. This chapter will discuss the
following aspects of printing reports:
•
Connecting the 824 to a Serial Printer
•
Printing Reports
•
Defining and Printing Tailored Reports
•
Printing a Custom Report
While most users will normally print 824 data using a computer, it is possible to print both graphical and tabular data
reports directly from the 824 to virtually any serial printer.
Printouts range from high resolution presentation quality
reports when printing to a laser printer because of the instrument’s PDL-3 (page description language) capabilities, to
draft-quality tabular data reports that can also be printed to a
dot matrix printer.
Connecting the 824 to a Serial Printer
Another cable is available for
certain printers that have a 9-pin
female “D” connector (CBL091).
If your printer does not have either
of these connectors, it is likely not a
serial printer. Do not attempt to
connect the 824 as damage may
result.
2/6/17
Make sure the System 824 and your printer are turned off
before initiating any of the following steps.
Step 1
Connect the provided (CBL002) serial cable’s 8pin mini DIN connector to the System 824 serial
port.
Step 2
Connect the serial cable’s 25-pin male “D” connector to your printer’s serial port.
Step 3
Turn on your printer and the System 824.
Printing a Report
8-1
Printing Reports
Step 1
Press the D Data key and use the Recall Files
menu to recall the measurement record that you
want to print. You may not need to recall a file if
you want to print something in memory that has
not been stored.
Depending on whether you have
selected an SSA, ISM, LOG, or RTA
instrument from the Setup menu you
will have a different Print menu
available. The screen shown is for
the SSA instrument.
Step 2
Press the P Print key. The following screen
appears:
The TAL and FFT instruments do not
generate any reports.
The Print menu provides different options depending on
instrument type.
The following table shows the menu options for the SSA,
ISM, LOG and RTA Print menus:
8-2
Menu Item
Options/Description
Available To:
Status
[shows the status of the printing job]
SSA, ISM, LOG,
RTA
Settings
Printer Type
Printer Baud
Flow Control
SSA, ISM, LOG,
RTA
SPL Report
[prints an SPL report]
ISM
Summary
[prints a summary report]
SSA, LOG, RTA
Tailored
[prints the tailored report]
SSA, LOG
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Recall Format
Summary
Tailored
All, short
All, long
None enabled
SSA, LOG
Customize
[allows you to select the print
options for an instrument ID and
customize your reports - see the
section on “Printing a Custom
Report”]
SSA, LOG, RTA
Print
[prints the report]
SSA, ISM, LOG,
RTA
Step 3
Depending
on
your
printer
configuration you may have to
modify the Printer Settings for
Printer Baud Rate and Flow
Control.
2/6/17
Use the u and d arrow keys to highlight Settings, then press the r arrow key or c Check
key to select it. The following menu appears:
Use the table below to set up the printer settings by using the
u and d arrow keys to highlight “Printer Type”,
“Printer Baud”, and “Flow Control” and then press the c
Check key to select the correct option for each.
Menu Item
Options
Printer Type
ASCII, Epson, IBM, HPJet, HPLzr
Printer Baud
300, 1200, 2400, 9600, 19200,
28800, 57600, 115 K
Flow Control
None, Hdwr, XOff, Both
Printing a Report
8-3
The title printed on your report will
correspond to the Title setting you
have configured in the Setup menu
for the selected ID.
Step 4
Use the l arrow key to return to the main Print
menu. You will notice that there is a paper page
icon P next to the “Summary” menu item. This
means that a report will be printed by highlighting
“Summary” and pressing the Check c key.
Step 5
Your Report will now begin printing and the Status screen will appear.
Press the c check key to abort the printing job.
Defining and Printing Tailored Reports
In the System 824, Tailored Reports
are available to the SSA and LOG
instruments.
With the System 824, a tailored report setting for each SSA
or LOG instrument ID can be created (i.e. each user can set
up their own user-defined print settings). Therefore, each
SSA or LOG instrument ID can have its own pre-set customized report settings. This section discusses how to define and
print tailored reports for the SSA and LOG instruments.
Selecting “Tailored Report” under
the Print menu copies the report
settings under “Define Report” from
the Setup Menu for the SSA and LOG
instruments for printing.
The following table shows the available settings for a Tailored report for the SSA instrument:
8-4
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2/6/17
Menu Item
Options
Unformatted
No
Yes
Data Report
No
Yes
Setup Report
No
Yes
Intv Report
No
Short
Long
History Report
No
Yes
The settings for a LOG instrument Tailored report are shown
under “Tailored Report Template (LOG instrument)” on
page 8-13.
The following provides an example of how to define and
print a tailored report:
Step 1
2/6/17
Press the S Setup key to bring up the Setup
menu. Highlight the Edit Settings menu item and
pressr arrow key or the c Check key to select
it.
Printing a Report
8-5
8-6
Step 2
Using the uand darrow keys, highlight the
Advanced item, then select it using the r arrow
key or the c Check key. The following screen
appears:
Step 3
Using the uand darrow keys, highlight the
Define Report item, then select it using the r
arrow key or the c Check key. The following
screen appears:
Step 4
Use the u and d arrow keys to scroll
through the available report settings. Use the c
Check key to select and change the options for
each type of report.
Step 5
Press the P Print key to bring up the Print menu.
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For your report to print properly,
your printer must be connected as
described in “Connecting the 824 to
a Serial Printer” on page 8-1 and
configured as described in “Printing
Reports” on page 8-2.
Step 6
Using the uand darrow keys highlight the
Tailored item, then select it using therarrow
key or the c Check key and your “Tailored”
report will begin printing.
NOTE: Make sure you save your Instrument ID before you change to a different
Instrument ID, otherwise all your newly
defined tailored print settings will be
lost.
Using the Recall Format (SSA and LOG instruments only)
The Recall Format menu allows you to customize the Summary report or the Tailored report and gives you two more
customized reports called All, Long and All, Short. When
the summary report is recalled, the Customize menu is
changed to reflect those parameters which will be printed in
the summary and tailored reports.
The Customize menu is formatted with all of the parameters
for each report selected in the Recall Format menu. You can
choose to print the default parameters that are recalled for
each report or you can go into the Customize menu and
make further changes to the parameters.
Before beginning to Print, always recall the file and select
the data that you would like to print. The following shows
how to print from the Recall Format:
2/6/17
Printing a Report
8-7
Step 1
Default Settings Values for the
Recall Format Reports
To print from the Recall Format menu press the
P PRINT key. The following screen appears:
Step 2
Use the u and d arrow keys to highlight the
Recall Format menu. Press the c key and the following screen appears:
Step 3
Use the u and d arrow keys and select the
report that you want to print (Summary, Tailored,
All,Short, All,Long, or None Enabled.
The following tables show the default settings for each of
the templates available from the Recall Format menu (Summary, Tailored, All, Long, All, Short, and None Enabled).
Summary Report Template
This template shows the default settings for the Summary
Report. The Summary Report includes the Data Report and
the Log Report.
After selecting the template, you can modify it as explained
in “Printing a Custom Report” on page 8-23.
8-8
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Summary Report Template (SSA instrument)
Report Settings
Lower Level
Report Settings
Description
Unformatted [No]
A dump of all Read, Query and Interval remote commands.
Multiple values are comma delimited.
Data Report [Yes]
This shows general information such as Leq, SEL, Dose, Projected Dose, Lmin,
Lmax, Peak, Ln’s, exceedance, and calibration logs.
Setup Report [No]
Print the settings and their values for the SSA instrument.
Intv Report [No]
Leq, SEL, Lmin, Lmax, Peak, Uwpk, exceedances, time, date, and duration in
the short report. The Long reports adds the Ln values and Spectral LNs for the
Interval.
Hist Report [No]
Leq for each time history period.
Print Range
Histograms
2/6/17
Intv Report [No]
You can customize the interval report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest interval record to be printed.
Highest Record (65535)
Selects the highest interval record to be printed.
Hist Report [No]
You can customize the time history report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest time history record to be printed.
Highest Record (>99999)
Selects the highest time history record to be printed.
SPL Histogram [No]
Prints SPL histogram and overall Spectral LN report.
Lowest Level (045)
Selects the lowest SPL histogram level to be printed.
Highest Level (095)
Selects the highest SPL histogram level to be printed.
Resolution (5.0)
Selects the SPL histogram resolution
Pk-1 Histogram [No]
You can customize the Peak1 Histogram report by choosing the long or short
report.
Lowest Level (110)
Selects the lowest Peak1 histogram level to be printed.
Highest Level (160)
Selects the highest Peak1 histogram level to be printed.
Resolution (5.0)
Selects the Peak1 histogram resolution
Pk-2 Histogram [No]
You can customize the Peak2 Histogram report by choosing the long or short
report.
Lowest Level (070)
Selects the lowest Peak2 histogram level to be printed.
Printing a Report
8-9
Summary Report Template (SSA instrument)
Histograms
Highest Level (120)
Selects the highest Peak2 histogram level to be printed.
Resolution (5.0)
Selects the Peak2 histogram resolution
Summary Report Template (LOG instrument)
Report Settings
Lower Level
Report Settings
Description
Unformatted [No]
A dump of all Read, Query and Interval remote commands.
Multiple values are comma delimited.
Data Report [Yes]
This shows general information such as Leq, SEL, Dose, Projected Dose, Lmin,
Lmax, Peak, Ln’s, exceedance, and calibration logs.
Log Report [Yes]
The run/stop log and with the date and time of each run/stop.
Setup Report [No]
Print the settings and their values for the LOG instrument.
SPL Histogram [No]
Shows 6 Ln values, Lmax, Lmin, and a bargraph of the level distribution.
Excd Report [No]
Lists Number of Record, Exchange Rate, Minimum Duration Time, Period,
Mode, Start Time, Leq, Max, Peak, Overloads, Unweighted Peak, Duration,
SEL, and Spectrum.
Intv Report [No]
Leq, SEL, Lmin, Lmax, Peak, Uwpk, exceedances, time, date, and duration in
the short report. The Long reports adds the Ln values for the Interval period.
Hist Report [No]
Leq for each time history period.
Daily Report [No]
Lists date, duration, Leq, Peak, Uwpk, Ldn, Lmax, CNEL, and Lmin.
Print Range
8-10
Excd Report [No]
You can customize the interval report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest exceedance record to be printed.
Highest Record (65535)
Selects the highest exceedance record to be printed.
Intv Report [No]
You can customize the interval report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest interval record to be printed.
Highest Record (65535)
Selects the highest interval record to be printed.
Hist Report [No]
You can customize the time history report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest time history record to be printed.
Highest Record (>99999)
Selects the highest time history record to be printed.
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Summary Report Template (LOG instrument)
Histograms
SPL Histogram [No]
You can customize the SPL Histogram report by choosing the long or short
report.
Lowest Level (045)
Selects the lowest SPL histogram level to be printed.
Highest Level (095)
Selects the highest SPL histogram level to be printed.
Resolution (5.0)
Selects the SPL histogram resolution
Pk-1 Histogram [No]
You can customize the Peak1 Histogram report by choosing the long or short
report.
Lowest Level (110)
Selects the lowest Peak1 histogram level to be printed.
Highest Level (160)
Selects the highest Peak1 histogram level to be printed.
Resolution (5.0)
Selects the Peak1 histogram resolution
Pk-2 Histogram [No]
You can customize the Peak2 Histogram report by choosing the long or short
report.
Lowest Level (070)
Selects the lowest Peak2 histogram level to be printed.
Highest Level (120)
Selects the highest Peak2 histogram level to be printed.
Resolution (5.0)
Selects the Peak2 histogram resolution
Tailored Report
This template shows the default settings for the Tailored
Report. The Tailored Report uses the settings from the
“Define Report” menu under the S Setup key. This allows
you to create a custom report for any SSA or LOG instrument ID.
The Tailored Report includes the Data Report, Log Report,
Setup Report, Interval Report (Short), Exceedance Report,
and the Daily Report.
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Printing a Report
8-11
After selecting the template you can modify it as explained
in “Printing a Custom Report” on page 8-23.
Tailored Report Template (SSA instrument)
Report Settings
Lower Level
Report Settings
Description
Unformatted [No]
A dump of all Read, Query and Interval remote commands. Multiple values
are comma delimited.
Data Report [Yes]
This shows general information such as Leq, SEL, Dose, Projected Dose, Lmin,
Lmax, Peak, Ln’s, exceedance, and calibration logs.
Setup Report [Yes]
Print the settings and their values for the SSA instrument.
Intv Report [Short]
Leq, SEL, Lmin, Lmax, Peak, Uwpk, exceedances, time, date, and duration in
the short report. The Long reports adds the Ln values and Spectral LNs for the
Interval period.
Hist Report [No]
Leq for each time history period.
Print Range
Histograms
8-12
Intv Report [Short]
You can customize the interval report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest interval record to be printed.
Highest Record (65535)
Selects the highest interval record to be printed
Hist Report [No]
You can customize the time history report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest interval record to be printed.
Highest Record (>99999)
Selects the highest interval record to be printed
SPL Histogram [No]
Prints SPL histogram and overall Spectral LN report.
Lowest Level (045)
Selects the lowest SPL histogram level to be printed.
Highest Level (095)
Selects the highest SPL histogram level to be printed.
Resolution (5.0)
Selects the SPL histogram resolution
Pk-1 Histogram [No]
You can customize the Peak1 Histogram report by choosing the long or short
report.
824 Reference Manual
2/6/17
Tailored Report Template (SSA instrument)
Histograms
Lowest Level (110)
Selects the lowest Peak1 histogram level to be printed.
Highest Level (140)
Selects the highest Peak1 histogram level to be printed.
Resolution (5.0)
Selects the Peak1 histogram resolution
Pk-2 Histogram [No]
You can customize the Peak2 Histogram report by choosing the long or short
report.
Lowest Level (070)
Selects the lowest Peak2 histogram level to be printed.
Highest Level (120)
Selects the highest Peak2 histogram level to be printed.
Resolution (5.0)
Selects the Peak2 histogram resolution
Tailored Report Template (LOG instrument)
Report Settings
Lower Level
Report Settings
Description
Unformatted [No]
A dump of all Read, Query and Interval remote commands.
Multiple values are comma delimited.
Data Report [Yes]
This shows general information such as Leq, SEL, Dose, Projected Dose, Lmin,
Lmax, Peak, Ln’s, exceedance, and calibration logs.
Log Report [Yes]
The run/stop log and with the date and time of each run/stop.
Setup Report [No]
Print the settings and their values for the LOG instrument.
SPL Histogram [No]
The 6 Ln values, Lmax, Lmin, and a bargraph of the level distribution.
Intv Report [Short]
Leq, SEL, Lmin, Lmax, Peak, Uwpk, exceedances, time, date, and duration in
the short report. The Long reports adds the Ln values for the Interval period.
Hist Report [Yes]
Leq for each time history period.
Excd Report[Short]
Lists number of Record, Exchange Rate, Minimum Duration Time, Period,
Mode, Start Time, Leq, Max, Peak, Overloads, Unweighted Peak, Duration,
SEL, and Spectrum.
Daily Report[Short]
Lists date, duration, Leq, Peak, Unweighted Peak, Ldn, Lmax, CNEL, and
Lmin.
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Printing a Report
8-13
Tailored Report Template (LOG instrument)
Print Range
Histograms
Intv Report [Short]
You can customize the interval report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest interval record to be printed.
Highest Record (65535)
Selects the highest interval record to be printed.
Hist Report [Yes]
You can customize the time history report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest time history record to be printed.
Highest Record (>99999)
Selects the highest time history record to be printed.
SPL Histogram [No]
You can customize the SPL Histogram report by choosing the long or short
report.
Lowest Level (040)
Selects the lowest SPL histogram level to be printed.
Highest Level (090)
Selects the highest SPL histogram level to be printed.
Resolution (5.0)
Selects the SPL histogram resolution
Pk-1 Histogram [No]
You can customize the Peak1 Histogram report by choosing the long or short
report.
Lowest Level (110)
Selects the lowest Peak1 histogram level to be printed.
Highest Level (140)
Selects the highest Peak1 histogram level to be printed.
Resolution (5.0)
Selects the Peak1 histogram resolution
Pk-2 Histogram [No]
You can customize the Peak2 Histogram report by choosing the long or short
report.
Lowest Level (070)
Selects the lowest Peak2 histogram level to be printed.
Highest Level (120)
Selects the highest Peak2 histogram level to be printed.
Resolution (5.0)
Selects the Peak2 histogram resolution
All, Short Report
This template shows the default settings for the All, Short
Report. The All, Short Report prints all of the reports. Those
reports with a Short version are printed in the short form.
After selecting the template you can modify it as explained
in “Printing a Custom Report” on page 8-23.
8-14
824 Reference Manual
2/6/17
All, Short Report Template (SSA instrument)
Report Settings
Lower Level
Report Settings
Description
Unformatted [No]
A dump of all Read, Query and Interval remote commands.
Multiple values are comma delimited.
Data Report [Yes]
This shows general information such as Leq, SEL, Dose, Projected Dose, Lmin,
Lmax, Peak, Ln’s, exceedance, and calibration logs.
Setup Report [Yes]
Print the settings and their values for the SSA instrument.
Intv Report [Short]
Leq, SEL, Lmin, Lmax, Peak, Uwpk, exceedances, time, date, and duration in
the short report. The Long reports adds the Ln values and Spectral LNs for the
Interval period.
Hist Report [Yes]
Leq for each time history period.
Print Range
Histograms
2/6/17
Intv Report [Short]
You can customize the interval report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest interval record to be printed.
Highest Record (65535)
Selects the highest interval record to be printed.
Hist Report [Yes]
You can customize the time history report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest time history record to be printed.
Highest Record (>99999)
Selects the highest time history record to be printed.
SPL Histogram [Yes]
Prints SPL histogram and overall Spectral LN report.
Lowest Level (045)
Selects the lowest SPL histogram level to be printed.
Highest Level (095)
Selects the highest SPL histogram level to be printed.
Resolution (5.0)
Selects the SPL histogram resolution
Pk-1 Histogram [Yes]
You can customize the Peak1 Histogram report by choosing the long or short
report.
Lowest Level (110)
Selects the lowest Peak1 histogram level to be printed.
Highest Level (160)
Selects the highest Peak1 histogram level to be printed.
Resolution (5.0)
Selects the Peak1 histogram resolution
Pk-2 Histogram [Yes]
You can customize the Peak2 Histogram report by choosing the long or short
report.
Lowest Level (070)
Selects the lowest Peak2 histogram level to be printed.
Printing a Report
8-15
All, Short Report Template (SSA instrument)
Histograms
Highest Level (120)
Selects the highest Peak2 histogram level to be printed.
Resolution (5.0)
Selects the Peak2 histogram resolution
All, Short Report Template (LOG instrument)
Report Settings
Lower Level
Report Settings
Description
Unformatted [No]
A dump of all Read, Query and Interval remote commands.
Multiple values are comma delimited.
Data Report [Yes]
This shows general information such as Leq, SEL, Dose, Projected Dose, Lmin,
Lmax, Peak, Ln’s, exceedance, and calibration logs.
Log Report [Yes]
The run/stop log and with the date and time of each run/stop.
Setup Report [Yes]
Print the settings and their values for the LOG instrument.
SPL Histogram [Yes]
The 6 Ln values, Lmax, Lmin, and a bargraph of the level distribution.
Intv Report [Short]
Leq, SEL, Lmin, Lmax, Peak, Uwpk, exceedances, time, date, and duration in
the short report. The Long reports adds the Ln values for the Interval period.
Hist Report [Yes]
Leq for each time history period.
Print Range
8-16
Intv Report [Short]
You can customize the interval report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest interval record to be printed.
Highest Record (65535)
Selects the highest interval record to be printed.
Hist Report [Yes]
You can customize the time history report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest time history record to be printed.
Highest Record (>99999)
Selects the highest time history record to be printed.
824 Reference Manual
2/6/17
All, Short Report Template (LOG instrument)
Histograms
SPL Histogram [Yes]
You can customize the SPL Histogram report by choosing the long or short
report.
Lowest Level (045)
Selects the lowest SPL histogram level to be printed.
Highest Level (095)
Selects the highest SPL histogram level to be printed.
Resolution (5.0)
Selects the SPL histogram resolution
Pk-1 Histogram [Yes]
You can customize the Peak1 Histogram report by choosing the long or short
report.
Lowest Level (110)
Selects the lowest Peak1 histogram level to be printed.
Highest Level (160)
Selects the highest Peak1 histogram level to be printed.
Resolution (5.0)
Selects the Peak1 histogram resolution
Pk-2 Histogram [Yes]
You can customize the Peak2 Histogram report by choosing the long or short
report.
Lowest Level (070)
Selects the lowest Peak2 histogram level to be printed.
Highest Level (120)
Selects the highest Peak2 histogram level to be printed.
Resolution (5.0)
Selects the Peak2 histogram resolution
All, Long Report
This template shows the default settings for the All, Long
Report. The All, Long Report prints all of the reports. Those
reports with a long version are printed in the long form.
After selecting the template, you can modify it as explained
in “Printing a Custom Report” on page 8-23.
All, Long Report Template (SSA instrument)
Report Settings
Lower Level
Report Settings
Description
Unformatted [No]
A dump of all Read, Query and Interval remote commands.
Multiple values are comma delimited.
Data Report [Yes]
This shows general information such as Leq, SEL, Dose, Projected Dose, Lmin,
Lmax, Peak, Ln’s, exceedance, and calibration logs.
Setup Report [Yes]
Print the settings and their values for the SSA instrument.
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Printing a Report
8-17
All, Long Report Template (SSA instrument)
Intv Report [Long]
Leq, SEL, Lmin, Lmax, Peak, Uwpk, exceedances, time, date, and duration in
the short report. The Long reports adds the Ln values and Spectral LNs for the
Interval period.
Hist Report [Yes]
Leq for each time history period.
Print Range
Histograms
Intv Report [Long]
You can customize the interval report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest interval record to be printed.
Highest Record (65535)
Selects the highest interval record to be printed.
Hist Report [Yes]
You can customize the time history report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest time history record to be printed.
Highest Record (>99999)
Selects the highest time history record to be printed.
SPL Histogram [Yes]
Prints SPL histogram and overall Spectral LN report.
Lowest Level (045)
Selects the lowest SPL histogram level to be printed.
Highest Level (095)
Selects the highest SPL histogram level to be printed.
Resolution (1.0)
Selects the SPL histogram resolution
Pk-1 Histogram [Yes]
You can customize the Peak1 Histogram report by choosing the long or short
report.
Lowest Level (110)
Selects the lowest Peak1 histogram level to be printed.
Highest Level (140)
Selects the highest Peak1 histogram level to be printed.
Resolution (1.0)
Selects the Peak1 histogram resolution
Pk-2 Histogram [Yes]
You can customize the Peak2 Histogram report by choosing the long or short
report.
Lowest Level (070)
Selects the lowest Peak2 histogram level to be printed.
Highest Level (120)
Selects the highest Peak2 histogram level to be printed.
Resolution (1.0)
Selects the Peak2 histogram resolution
All, Long Report Template (LOG instrument)
Report Settings
Unformatted [No]
8-18
Lower Level
Report Settings
Description
A dump of all Read, Query and Interval remote commands.
Multiple values are comma delimited.
824 Reference Manual
2/6/17
All, Long Report Template (LOG instrument)
Data Report [Yes]
This shows general information such as Leq, SEL, Dose, Projected Dose, Lmin,
Lmax, Peak, Ln’s, exceedance, and calibration logs.
Log Report [Yes]
The run/stop log and with the date and time of each run/stop.
Setup Report [Yes]
Print the settings and their values for the LOG instrument.
SPL Histogram [Yes]
The 6 Ln values, Lmax, Lmin, and a bargraph of the level distribution.
Intv Report [Long]
Leq, SEL, Lmin, Lmax, Peak, Uwpk, exceedances, time, date, and duration in the
short report. The Long reports adds the Ln values for the Interval period.
Hist Report [Yes]
Leq for each time history period.
Print Range
Histograms
2/6/17
Intv Report [Long]
You can customize the interval report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest interval record to be printed.
Highest Record (65535)
Selects the highest interval record to be printed.
Hist Report [Yes]
You can customize the time history report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest time history record to be printed.
Highest Record (>99999)
Selects the highest time history record to be printed.
SPL Histogram [Yes]
You can customize the SPL Histogram report by choosing the long or short
report.
Lowest Level (045)
Selects the lowest SPL histogram level to be printed.
Highest Level (095)
Selects the highest SPL histogram level to be printed.
Resolution (1.0)
Selects the SPL histogram resolution
Pk-1 Histogram [Yes]
You can customize the Peak1 Histogram report by choosing the long or short
report.
Lowest Level (110)
Selects the lowest Peak1 histogram level to be printed.
Highest Level (140)
Selects the highest Peak1 histogram level to be printed.
Resolution (5.0)
Selects the Peak1 histogram resolution
Pk-2 Histogram [Yes]
You can customize the Peak2 Histogram report by choosing the long or short
report.
Lowest Level (070)
Selects the lowest Peak2 histogram level to be printed.
Highest Level (120)
Selects the highest Peak2 histogram level to be printed.
Resolution (1.0)
Selects the Peak2 histogram resolution
Printing a Report
8-19
None Enabled Report
When “None Enable” is selected from the Recall Format
menu then all of the reports are disabled and will not be
printed. This allows you greater ease in printing only a
selected number of reports.
After selecting this template you can modify it as explained
in “Printing a Custom Report” on page 8-23.
None Enabled Report Template (SSA instrument)
Report Settings
Lower Level
Report Settings
Description
Unformatted [No]
A dump of all Read, Query and Interval remote commands.
Multiple values are comma delimited.
Data Report [No]
This shows general information such as Leq, SEL, Dose, Projected Dose, Lmin,
Lmax, Peak, Ln’s, exceedance, and calibration logs.
Setup Report [No]
Print the settings and their values for the SSA instrument.
Intv Report [No]
Leq, SEL, Lmin, Lmax, Peak, Uwpk, exceedances, time, date, and duration in
the short report. The Long reports adds the Ln values and Spectral LNs for the
Interval period.
Hist Report [No]
Leq for each time history period.
Print Range
8-20
Intv Report [No]
You can customize the interval report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest interval record to be printed.
Highest Record (65535)
Selects the highest interval record to be printed.
Hist Report [No]
You can customize the time history report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest time history record to be printed.
Highest Record (>99999)
Selects the highest time history record to be printed.
824 Reference Manual
2/6/17
None Enabled Report Template (SSA instrument)
Histograms
SPL Histogram [No]
Prints SPL histogram and overall Spectral LN report.
Lowest Level (045)
Selects the lowest SPL histogram level to be printed.
Highest Level (095)
Selects the highest SPL histogram level to be printed.
Resolution (5.0)
Selects the SPL histogram resolution
Pk-1 Histogram [No]
You can customize the Peak1 Histogram report by choosing the long or short
report.
Lowest Level (110)
Selects the lowest Peak1 histogram level to be printed.
Highest Level (160)
Selects the highest Peak1 histogram level to be printed.
Resolution (5.0)
Selects the Peak1 histogram resolution
Pk-2 Histogram [No]
You can customize the Peak2 Histogram report by choosing the long or short
report.
Lowest Level (070)
Selects the lowest Peak2 histogram level to be printed.
Highest Level (120)
Selects the highest Peak2 histogram level to be printed.
Resolution (5.0)
Selects the Peak2 histogram resolution
None Enabled Report (LOG instrument)
Report Settings
Lower Level
Report Settings
Description
Unformatted [No]
A dump of all Read, Query and Interval remote commands.
Multiple values are comma delimited.
Data Report [No]
This shows general information such as Leq, SEL, Dose, Projected Dose, Lmin,
Lmax, Peak, Ln’s, exceedance, and calibration logs.
Log Report [No]
The run/stop log and with the date and time of each run/stop.
Setup Report [No]
Print the settings and their values for the LOG instrument.
SPL HIstogram [No]
The 6 Ln values, Lmax, Lmin, and a bargraph of the level distribution.
Intv Report [No]
Leq, SEL, Lmin, Lmax, Peak, Uwpk, exceedances, time, date, and duration in the
short report. The Long reports adds the Ln values for the Interval period.
Hist Report [No]
Leq for each time history period.
2/6/17
Printing a Report
8-21
None Enabled Report (LOG instrument)
Print Range
Histograms
8-22
Intv Report [No]
You can customize the interval report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest interval record to be printed.
Highest Record (65535)
Selects the highest interval record to be printed.
Hist Report [No]
You can customize the time history report by choosing the long or short report.
Lowest Record (00000)
Selects the lowest time history record to be printed.
Highest Record (>99999)
Selects the highest time history record to be printed.
SPL Histogram [No]
You can customize the SPL Histogram report by choosing the long or short report.
Lowest Level (045)
Selects the lowest SPL histogram level to be printed.
Highest Level (095)
Selects the highest SPL histogram level to be printed.
Resolution (5.0)
Selects the SPL histogram resolution
Pk-1 Histogram [No]
You can customize the Peak1 Histogram report by choosing the long or short
report.
Lowest Level (110)
Selects the lowest Peak1 histogram level to be printed.
Highest Level (160)
Selects the highest Peak1 histogram level to be printed.
Resolution (5.0)
Selects the Peak1 histogram resolution
Pk-2 Histogram [No]
You can customize the Peak2 Histogram report by choosing the long or short
report.
Lowest Level (070)
Selects the lowest Peak2 histogram level to be printed.
Highest Level (120)
Selects the highest Peak2 histogram level to be printed.
Resolution (5.0)
Selects the Peak2 histogram resolution
824 Reference Manual
2/6/17
Printing a Custom Report
The ISM instrument does not allow
printing customized reports.
In addition to being able to print your standard reports for
data taken with the SSA, LOG, or RTA instruments, you can
also further customize your report definitions at print time
with the Print menu’s Customize option.
The following provides an example of printing a customized
report:
For your report to print properly,
your printer must be connected as
described in “Connecting the 824 to
a Serial Printer” on page 8-1 and
configured as described in “Printing
Reports” on page 8-2.
2/6/17
Step 1
Press P key to bring up the Print menu.
Step 2
Use the uand darrow keys to highlight the
Customize item, then select it using ther arrow
key or the c Check key. The following screen
appears:
Step 3
Use the u and d arrow keys to scroll
through the available report settings. Use the c
Check key to select the settings that you want to
modify, then make the modifications.
Step 4
Use the l arrow key to completely back out of
the Customize menu screen, then use the darrow key to highlight the Print item, then select it
using the c Check key. Your Customized report
will now print.
Printing a Report
8-23
The following table shows the available options under the
Customize menu for the SSA instrument:
Spectral LNs are printed in the Long
Intv Report.
Menu Items
Options
Unformatted
No
Yes
Data Report
No
Yes
Setup Report
No
Yes
Intv Report
No
Short
Long
Hist Report
No
Yes
Print Range
Intv Report (No, Short, Long)
-Lowest Record
-Highest Record
Hist Report (No, Yes)
-Lowest Record
-Highest Record
Histograms
8-24
824 Reference Manual
SPL Histogram (No, Yes)
Lowest Level
Highest Level
Resolution
Pk-1 Histogram (No, Yes)
Lowest Level
Highest Level
Resolution
Pk-2 Histogram (No, Yes)
Lowest Level
Highest Level
Resolution
2/6/17
The following table shows the available options under the
Customize menu for the LOG instrument:
2/6/17
Menu Items
Options
Unformatted
No
Yes
Data Report
No
Yes
Log Report
No
Yes
Setup Report
No
Yes
SPL Histogram
No
Yes
Excd Report
No
Short
Long
Intv Report
No
Short
Long
Hist Report
No
Yes
Daily Report
No
Yes
Printing a Report
8-25
NOTE: See the section “Summary
Report Template” on page 8-8 descriptions of each report for the SSA and LOG
instruments.
Print Range
Excd Report (No, Short, Long)
-Lowest Record
-Highest Record
Intv Report (No, Short, Long)
-Lowest Record
-Highest Record
Hist Report (No, Yes)
-Lowest Record
-Highest Record
Histograms
SPL Histogram (No, Yes)
Lowest Level
Highest Level
Resolution
Pk-1 Histogram (No, Yes)
Lowest Level
Highest Level
Resolution
Pk-2 Histogram (No, Yes)
Lowest Level
Highest Level
Resolution
The following table shows the available options under the
Customize menu for the RTA instrument:
(RTA instrument)
Report
Options
Description
Data Report
No
Yes
Name and Address of Company and date printed.
Live
No
Yes
Shows beginning and ending date and time, runtime, type of Averaging, sample
rate, trigger phase ad Live Spectrum.
Leq
No
Yes
Shows beginning and ending date and time, runtime, type of Averaging, sample
rate, trigger phase ad Leq Spectrum.
Max
No
Yes
Shows beginning and ending date and time, runtime, type of Averaging, sample
rate, trigger phase ad Max Spectrum.
Min
No
Yes
Shows beginning and ending date and time, runtime, type of Averaging, sample
rate, trigger phase ad Min Spectrum.
8-26
824 Reference Manual
2/6/17
(RTA instrument)
Autostore Rpt
No
Short
Long
The Short report prints the Leq, Lmax and Lmin spectrum. In addition,
the ByTime Spectrums are included in the Long report.
Lowest Record
0 - 65535
The lowest Autostore Record to print.
Highest Record
0 - 65535
The highest Autostore Record to print.
Lowest
ByTime
0 - 65535
The lowest ByTime Spectrum to print.
Highest
ByTime
0 - 65535
The highest ByTime Spectrum to print.
RT-60 Report
No
Yes
Prints the calculated RT60 for every octave or 1/3 octave band.
Avg Hist
No
Yes
Spatial Average History
Lowest Record
0 - 65535
The lowest Spatial Average History Spectrum to print
Highest Record
0 - 65535
The highest Spatial Average History Spectrum to print
Setup Report
No
Yes
Print the settings and their values for the RTA instrument.
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Printing a Report
8-27
8-28
824 Reference Manual
2/6/17
APPENDIX
9
Performing a Sound Level
Measurement
Due to the many features of the System 824 and the variety
of measurements it is capable of performing, there is a great
deal of instructive material in the preceding chapters. In this
chapter, to assist the new user in performing a basic sound
level measurement, we work our way through the specific
steps necessary to perform an accurate measurement.
Configuration of the System
The System 824 should be configured as shown in Figure 11 on page -1-8 with the preamplifier connected to the front
of the instrument and the microphone connected to the end
of the preamplifier. If desired, a microphone extenstion
cable may be connected between the preamplifier and the
body of the 824. For more details on the positioning of the
824 and the permitted length of the extension cable, see
“Positioning the Meter” on page 9-7.
Selecting a Measurement Mode
The System 824 can measure sound pressure level using any
of the following modes:
2/6/17
•
Integrating Sound Meter (ISM) measures sound level
parameters, which are stored manually by the operator.
•
Logging SLM (LOG) measures sound level parameters
and automatically stores the data based on a number of
different user-configured data logging methodologies
such as Time History, Intervals, Exceedance History and
Daily History).
Performing a Sound Level Measurement
9-1
•
Sound
Spectrum Analyzer
(SSA)
which
simultaneously measures sound level parameters and
real-time frequency spectra (1/1 or 1/3 octave
bandwidths). These data can be stored manually by the
operator or automatically using the Time History and/or
Interval methodologies.
Details on the functionality of each of these see “System 824
Virtual Instruments” on page 6-1.
Select the desired measurement mode (ISM, LOG or SSA)
as described in section ”Selecting and Modifying Instrument
Definitions (IDs)” on page 4-11. If you are just beginning to
use the instrument, there will be only one ID (permanent)
available for each of these modes. However, if other IDs
have been created and stored using parameters different
from the default values used in the permanent setups, these
will also appear with the name defined for each at the time
of storage.
Selecting a Measurement ID
If a previous setup had been created and saved, this setup
can be recalled by following the procedure described in
“Selecting a Measurement Setup” on page 2-6.
9-2
824 Reference Manual
2/6/17
Editing the Microphone Parameters
The microphone to be used will either be a traditional
condenser microphone, which requires a polarization
voltage, or it will be an electret (prepolarized) microphone.
Further, if it is a free-field microphone and the measurement
is best performed using a random incidence microphone, the
user can select to implement a random incidence correction
to the measurement.
The procedure for selecting these parameters is described in
section ”Customizing Settings” on page 7-2, specifically the
sections “Transducer Setting - (SSA, LOG, ISM)” on page 78 and “Random Incidence Microphone Correction (Available to all Instrument types)” on page 7-8.
Calibration
The System 824 automatically changes the frequency
weighting to C-Weighting during the calibration process.
Therefore, calibrators having frequencies which correspond
to the flat region of the C-weight curve (200 Hz - 1.25 kHz)
may be used. Larson Davis recommends the following
sound level calibrators:
•
Larson Davis Model CAL200; 94/114 dB @ 1 kHz
•
Larson Davis Model CAL250: 114 dB @ 250 Hz
The procedure for performing a calibration is described in
detail in section “Turning On and Calibrating the System
824” on page 4-1.
If the Cal Level is not already set to the level provided by
the calibrator being used, this level must be changed by the
user. To do this, use the dkey to highlight Cal Level and
press the c key. Use the horizontal and vertical arrow keys
to edit the level to match that of the calibrator and press the
c key to enter the new value.
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Performing a Sound Level Measurement
9-3
Entering the Noise Floor Values
When measuring low levels of sound, substantial errors can
occur when the sound level to be measured is near that of the
noise floor of the measuring instrument. An accurate
measurement is obtained when the measured sound level is
at least 10 dB above the noise floor. When this condition is
not fulfilled, we say the instrument is in an Under Range
condition. which we indicate on the display. The noise due
to the front end electronics and the microphone preamplifier
are known, but the thermal noise of the microphone must be
entered by the user based on specifications provided by the
manufacturer. The A-weighted noise floor values for Larson
Davis microphones are presented in the following table.
Microphone Model Number
2520
2530
2540
377B41
2559
377A
60
2570
2575
Nominal Thermal Noise, dB(A)
30
31
20
15
18
15
10
10
The procedure for entering the noise floor value for the
microphone to be used is described in the section “TTools
Key” on page 3-18, subsection “Calibration” on page 3-22
under the heading Noise Floor.
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Editing the Measurement Parameters
NOTE: If you are recalling a
measurement ID which has already been
configured for the measurement you wish
to perform, then you can skip to the next
section.
Leq
Peak
The design of the System 824 permits the simultaneous
measurement of the following sound level parameters, a
feature we call “Any Data”:
Live SPL
Lmax
Lmin
Detectors
Detectors
Detectors
Slow
Fast
Impl
Slow
Fast
Impl
Slow
Fast
Impl
A











C











Flat











Note: The detector used to create
Leq is a pure integrating true RMS
detector which integrates the energy
over a specific period of time. It may
be as short as 1/32 second, in a time
history which may be as long as 24
hours. As a result, it does not include
decay artifacts of older instruments
that integrate the output of the
SLOW or FAST detectors.
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Peak Sound Pressure Level (Lpeak) with A, C and Flat
weighting.
Equivalent Continuous Sound Pressure Level (Leq) with
A, C and Flat weighting. A time history record can be
enabled to capture samples at periods as short as 1/8th of a
second.
Performing a Sound Level Measurement
9-5
The SLM display is shown below
Detector
Frequency
Weighting
Sound Level
Secondary Parameter
Secondary Parameter
Value
Measurement Time
Secondary Parameter
Frequency Weighting
Although the System 824 measures the sound pressure level
using multiple values of detector and frequency weighting, it
only displays a single value as shown above. For this
parameter, you have a choice of three detectors (averaging
time):
•
Slow
•
Fast
•
Impulse
and you have a choice of three frequency weightings:
9-6
•
A-weight
•
C-weight
•
Flat
824 Reference Manual
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Similarly, you have a choice of three frequency weightings
to be used for the display of the peak level.
•
A-weight
•
C-weight
•
Flat
The procedure for selecting these parameters is described in
section ”Customizing Settings” on page 7-2, specifically the
sections, “Weighting Setting - (SSA, LOG, ISM)” on page 76 and “Pk Weighting - (SSA, LOG, ISM)” on page 7-9.
Positioning the Meter
The meter will be either mounted upon a tripod or held in the
hand. In order to avoid the effect of sound reflections from
the body of the operator interfering with the measurement,
the meter should be located as far as possible from the body.
Thus, when actually performing the measurement, the
operator should place himself at a distance behind the
tripod-mounted meter, or extend the hand-held meter as far
from the body as is comfortable.
If desired, a microphone extension cable may be placed
between the meter and the preamplifier/microphone. When
doing so, take care that the preamplifier/microphone is held
or mounted in such a way to minimize the effect of
reflections on the sound field near the microphone.
Use of a Windscreen
Wind blowing across the microphone generates pressure
fluctuations on the microphone diaphragm which can
produce errors in the measurement. As a result, when
performing measurements in the presence of low level
airflows, it is recommended that a windscreen be placed
over the microphone. Larson Davis provides the WS001
windscreen, a 3 1/2” diameter ball made of open cell foam
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Performing a Sound Level Measurement
9-7
which can be placed over the microphone and preamplifier
as shown below.
To install the windscreen, hold the meter in one hand and the
windscreen in the other. Insert the microphone/preamplifier
assembly into the opening in the windscreen as shown below
and slide the windscreen completely down over the
preamplifier.
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Selecting the SLM Display
For sound level measurement, press the Vkey, use the
ukey to highlight SLM and press the c key to obtain
the display shown in “Editing the Measurement Parameters”
on page 9-5
Selecting the Measurement Range
ISM and LOG Modes
In the ISM mode, there are three range setting available:
•
Low
•
Normal
•
High
Although the range setting does not always appear on the
SLM display, it can be found by repeatedly pressing either
the uor dkey until the highlight is located in the lower
right corner of the display as shown below.
The upper and lower limits of sound pressure level which
can be measured for each of these scales are indicated in the
“RMS Measurement Range (LOG and ISM modes only)” on
page C-11.
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Performing a Sound Level Measurement
9-9
Selecting the Range Setting
When the range is highlighted as shown in the above
graphic, the range can be toggled between Normal and Low
by pressing the ror lkeys. If the approximate level is
known, select the range setting for which that level falls
nearest the middle of the measurement range. If it is not
known, select the Normal range which is usually adequate
for the majority of common measurements.
The range setting can also be selected using the setup menu.
In fact, this is the only way to select the High range.
Press the S key, the rkey, highlight SLM, press the c
key, highlight Range, and press the c
key to obtain the
following display
Highlight the desired range and press the c
the selection.
key to make
SSA Mode
The SSA Mode has a smaller measurement range than the
ISM and LOG Modes. As a result, rather than select a range
setting from among three choices, as done for the ISA and
LOG Modes, we will select a gain value which can range
from -20 to + 50 dB in steps of 10 dB. The usual practice is
to set the gain to 0 dB and later modify that as required to
obtain a good measurement without overload or under range
conditions.
Although the gain setting does not usually appear on the
SLM display, it can be found by repeatedly pressing either
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the uor dkey until the highlight is located in the lower
right corner of the display as shown below.
When the gain setting is highlighted, this can be changed by
repeatedly presssing the uor dkey until the desired
value of Gain appears.
Performing a Measurement
The procedure for performing a measurement is described in
the section “Performing a Measurement; SLM&RTA (SSA)”
on page 2-7. Among the important aspects covered are the
following:
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•
Stop, Pause and Erase Functions in section “Stop, Pause
and Back Erase Functions” on page 2-8.
•
Changing the Detector of the displayed SPL value in
section “Changing the detector of the displayed SPL
value” on page 2-8.
•
Changing the Frequency Weighting of the displayed SPL
value in section “Changing the frequency weighting of
the displayed SPL value” on page 2-9.
•
Changing the Displayed Secondary Parameter in section
“Changing the displayed secondary parameter” on page
2-10.
•
Changing the Frequency Weighting of the Displayed
Lpeak value in section “Changing the frequency
weighting of the displayed Lpeak value” on page 2-10.
Performing a Sound Level Measurement
9-11
After reaching equilibrium with the ambient environment
and switching the power on, the elapsed time until the meter
may be used to measure the sound level is as follows:
•
< 10 seconds using a prepolarized (electret) microphone
•
< 1 minute using a traditional condenser microphone
requiring a polarization voltage.
When performing an integrating measurement, the data is
available during and immediately following the
measurement time interval.
Averaging Time
The averaging time is determined by how long the
measurement is allowed to run, as indicated by the digital
display in the lower left of the screen. For low level
measurements where the measured level may be affected by
the system noise floor, it is recommended that an averaging
time of at least 30 seconds be used. For timed
measurements, the value of the averaging time can be preset
and the instrument configured to stop automatically after
that time as described in the section “Measuring for a Preset
Integration Time” on page 9-15.
Linearity Range
When making a measurement, the upper and lower linearity
range limits of the instrument for the setting presently in
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effect are indicated by the dark regions with light numbers
as indicated below.
Upper Limit of Linearity
Lower Limit of Linearity Range
Changing the range (ISM and LOG Modes) or gain (SSA
Mode will change these limits. For very low (high) level
measurements, it may be necessary to utilize a microphone
having a higher (lower) value of sensitivity in order to
perform a measurement within the linearity range of the
instrument.
Overload and Under Range Conditions
Overload Condition
When the input signal is too high, the electronics will
overload. This is indicated by a flashing OVLD text
message, as well as a flashing OL (for overload) in the upper
right corner of the display as shown below.
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Performing a Sound Level Measurement
9-13
This text message will continue as long as the overload
conditions continues, but it will disappear when the input
level drops below the overload level. However, the flashing
OL display will continue to appear in the same position as
shown below. This indicates that the data measured may not
be accurate due to the overloaded condition which occurred
during the measurement interval.
Reset
Press the R key to reset the measurement. This function is
described in greater detail in the section “R Reset Key” on
page 3-9. The reset facility clears an overload indication and
there is no delay time between the operation of the reset
facility and the re-initiation of a measurement.
Under Range Condition
NOTE: The noise level corresponding to
the microphone being used must have
been entered by the user, as described in
section “Entering the Noise Floor
Values” on page 9-4, in order for this
feature to function correctly.
When the sound level being measured is within 10 dB of the
noise floor, this will be indicated by a flashing downward
directed arrow in the upper right corner of the display as
shown below.
To avoid this condition, select a lower range (ISM or LOG
Mode) are a higher value of Gain (SSA Mode).
Max, Min and Peak Values
As stated in “Editing the Measurement Parameters” on page
9-5, Lmax and Lmin are measured for all combinations of
frequency weighting (A, C and Flat) and detection (Slow,
Fast and Impulse). Peak values are measured for A, C and
Flat frequency weighting. These max values represent the
highest value of each which was measured during the
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measurement time interval and the min. values represent the
lowest values measured during the same time interval. A
reset operation will reset these values to the values being
measured at the instant the reset operation is activated.
The nominal range for the measurement of Peak values
using A, C or Flat weighting are specified in the section
“Peak Measurement Range (LOG and ISM modes only)” on
page C-12.
Measuring for a Preset Integration Time
The System 824 can perform an integrated measurement
over a preset time in either the LOG or SSA Mode by
making use of the Interval measurement feature. For a
detailed description of setting up for an interval
measurement, see the section “LOG and SSA Interval
Settings” on page 7-35.
To measure a single interval, set Interval Autostop (Intv
Auto Stop) to On as described in the section “Intv Auto Stop
- (LOG, SSA)” on page 7-38. To measure and store data over
a series of equal time intervals, set Interval Autostop (Intv
Auto Stop) to Off.
The interval time can be set from 00:00:01 hh:mm:ss to
99:59:59 in steps of 1 second.
Timer Mode
The Clock/Timer Mode is used when it is desired that the
measurement begin at a preset date and time. This can
initiate either a single interval measurement or a sequence
depending upon whether the Interval Auto Stop is set to On
or Off, respectively.
Setup the measurement using the Clock/Timer Menu which
is accessed by pressing the S key, using the
uordkeys to highlight Clock/Timer and pressing the
c key. For details on the use of this menu see the section
“Clock/Timer” on page 3-23.
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Performing a Sound Level Measurement
9-15
Measuring using User-Selectable Thresholds
The System 824 can be setup to measure data associated
with Exceedance Events, defined as instances where the
sound pressure level exceeds a user-selected threshold. For a
detailed description of setting up the System 824 to measure
Exceedance Events, see the section “Logging SLM
Exceedance History Settings” on page 7-39.
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CHAPTER
10
Using the 824 Utility Software
The 824 Utility software is a powerful tool for use with the
System 824 from Larson Davis. This software will allow
you to control, setup, download and translate your 824
measurement data quickly and easily.
The 824 Utility program has three sections that perform the
functions on the 824.
•
The setup section provides support for creating, editing,
storing and retrieving setups from the 824 and from files.
•
The download section provides a means by which to
retrieve the measurement data from the 824.
•
The translate section provides support for translating the
downloaded measurement data, and displaying or printing it in a text format, or exporting the measurement data
to a spreadsheet program.
In this chapter we will discuss installing the software, getting the software started on your computer, connecting the
824 to the serial port of your computer, explain the Main
Screen Toolbar functions, and then go onto discuss each of
the three functions of the software in greater depth.
824 Utility Installation
To install the 824 Utility software package place the disk
(CD) into your CD-ROM drive. From Windows 95 press
START and then select the RUN menu item. A prompt will
appear to enter the program name. Enter “E:\824auto.exe”.
A new screen will appear with several menu items to choose
from.
Select “Install Software” from the menu items. Another
screen will appear with several more choices. Select
“INSTALL 824 Utility Software”. The 824 utility software
will automatically begin the installation process. The
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Using the 824 Utility Software
10-1
installer program will prompt you through the installation. A
message will appear indicating that the software was successfully installed.
Starting the 824 Utility Software
To start the 824 Utility software in Windows , press
START and then select the Programs/Larson Davis/824Util
menu item.
Connecting to Your Computer
To connect the 824 to a computer, use the CBL006 cable
included with your System 824. The round 8-pin connector
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plugs into the Serial port of the 824 and the 9-pin connector
plugs into a serial port on your computer.
You do not need to be connected to
the 824 in order to translate files
which
have
already
been
downloaded.
NOTE: The 824 will power on when it
senses anything on the serial connector.
You may notice the 824 powering on
automatically before you press the power
button.
2/6/17
Before any functions can be performed on the 824, you must
connect the 824 to the 824 Utility software. To connect to
the 824:
Step 1
Attach the CBL006 to the 824 and to the serial
port on the computer as described earlier.
Step 2
Start the 824 Utility program.
Step 3
Power on the 824.
Step 4
Press the Connect button on the tool bar.
Step 5
The connect dialog box will appear.
Using the 824 Utility Software
10-3
NOTE: See “Communication” on page
3-33 for details on changing the
communication parameters on the 824.
Step 6
Select the comport that your 824 is connected to,
select the baud rate, and press the connect button.
After a successful connection, the setup window will appear
with a system setup in the setup list box. The 824’s serial
number and title will be displayed on the setup dialog box
screen.
824 Utility Tool Bar
The tool bar for the 824 Utility program provides support for
the main functions of the 824 Utility program. All Toolbar
functions can also be performed from the pull down menus
at the top of the 824 Utility Software screen.
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Connect button. This button is used to
establish a connection to the 824. Pressing this
button will bring up the connect dialog box
where the connection parameters can be
defined.
Retrieve Setups from 824. This button will
retrieve all current setups in the 824.
Create new setup button. This button will
allow the user to create a new setup that can
then be saved to disk, or saved in the 824.
Open a setup from a computer file. This button
will allow the user to retrieve previously stored
setup files.
Store setup to disk. This button will allow the
user to store a setup to a disk.
Store setup in 824. This button will store the
setup in the 824. This function must be
performed before the setup can be used inside
the 824.
Setup window button. This button will activate
the setup window portion of the 824 Utility
Program
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Using the 824 Utility Software
10-5
Download window button. This button will
open the download section of the 824 Utility
program.
Translate window button. This button will
open the translate section of the program. It
will provide a file tree where the contents of
the downloaded measurement files can be
viewed.
Export measurement button. Exports the
currently selected measurement file to a user
defined spreadsheet program. This button will
only be active when you are in the translate
section of the program, and there is a
measurement file being displayed.
824 Utility Setup Window
The setup window is the default window that will open up
when the 824 Utility program is started. The setup window
will allow you to edit existing setups, retrieve setups from
the 824 or a file, create new setups, and store setups to the
824 or to a file.
The main setup window has 2 sections: the setup list box,
and the settings dialog section. The setup list box will list all
setups that have either been created or retrieved from the
824 or a disk file. The settings dialog section will allow you
to manipulate the setup.
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Setup List Box
Settings Tab Dialog
Retrieving setups from the 824
Setups stored in the 824 can be retrieved by clicking on the
Get Setup button on the tool bar or by selecting Get Setups
From 824 from the File Menu.
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Using the 824 Utility Software
10-7
Setups will be retrieved from the 824 and will be displayed
in the Setup listbox.
In the list of setup files, the system setup is the first setup
and is followed by all of the permanent and user-defined setups. In the setup list box, there are several parts of the Setup
title that can be used to identify the setup type.
The name of the ID is listed in the right hand column.
For the permanent ID’s, this will be the Larson Davis
instrument type. For a user defined ID, this can be anything that the user defines.
The three letter Larson Davis assigned
name is listed in the blue Ovals. This
indicates the type of instrument ID for
which the setup was created.
‘P’ stands for a permanent ID. This would be
an original setup defined at Larson Davis
and cannot be modified.
A lock icon in this place indicates a
user ID that has been locked so it cannot be modified.
No letter or an arrow indicates a modifiable User defined ID.
Highlighting one of the setups in the list displays all of the
available settings in the setup dialog box (right side of the
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window). The setups are organized and grouped similar to
the 824 menu structure in the instrument. Click on the different tabs to access all of the setup parameters.
Select different tabs to access
all of the setup functions.
Parameters can be entered manually,
or the pull down selections can be
used.
Modifying and Storing Setups to the 824
NOTE: If you change settings in the
Utility program to an active setup in the
824, those changes will not take effect in
the 82 unless the modified setup is reselected.
With the 824 Utility software you can make modifications to
any of the user defined setups and the system setup. For
example, in the System setup, you can change any of the
parameters for the Title, Calibration, Power, Date/Time,
Controls or Modem and then send the modified setup to the
824. To store the modified setup, select the Save Setup to
824 menu item from the File menu or click on the Store
Setup in 824 button on the tool bar.
Changing System Settings
The system selection on the setup list box contains the general settings for the 824. The selections here include, Title,
Options*, Calibration, Power, Date and Time, Controls and
Modem. To change one of these settings, click on the appropriate tab, and enter the changes.
*The Option Settings show what
options were purchased for this
instrument and can’t be changed. To
purchase an option, contact your
Larson Davis representative.
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Using the 824 Utility Software
10-9
Manipulating a Setup
10-10
To change any of the variables for a particular user defined
setup, select the setup. The appropriate setup tab dialog will
appear at the right of the setup list box. Select the setting you
wish to change and enter the new value.
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You can also access several setup functions by right clicking
on the Setup in the Setup list box.
The following functions can be accessed by pressing the
right mouse button while within the Setup list box. The
Setup Menu items will appear enabled or disabled depending on the setup selected. For example, it is not possible to
delete a permanent 824 setup, so the Delete Setup menu
item will be disabled if a permanent 824 setup is selected.
The Rename Setup button allows you to
rename the selected user defined setup.
The Make Setup Current button will cause the
selected setup to become the Active setup in
the 824.
The Lock Setup button will write-protect the
selected setup in the 824.
The Unlock Setup button will write-enable the
selected setup in the 824.
The Delete setup button will delete the selected
user defined setup from the 824.
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Using the 824 Utility Software
10-11
Saving Setups to Disk Files
Once you have created or modified a setup, you can store the
setup to a file. Select the Save Setup to a File menu item
from the File menu or click on the Save to File button on the
tool bar.
NOTE: The
system
setup
is
automatically updated each time the 824
Utility is connected to the 824.
The 824 Utility program will bring up a standard windows
save dialog box, where the file name and location of the
setup can be specified.
The System setup can be modified and stored back into the
824, but cannot be saved to a disk file.
Opening Setup Disk Files
To open a setup disk file select the Open Setup File menu
item from the File menu or click on the Open File button on
the tool bar.
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A standard windows Open File box will appear. Select the
file folder that contains the file and select the setup file you
want.
The setup appears in the Select Setup list box. You can then
select (highlight) the desired setup in the list. The highlighted setup can then be sent to the 824 by selecting the
Save Setup to 824 menu item from the File menu.
Other menu items available in the Setup Menu include
renaming, locking, unlocking, deleting, or making the
selected setup the active setup.
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Using the 824 Utility Software
10-13
Creating a New Setup
You create new setups by selecting the New Setup menu
item from the File menu or by selecting the New Setup button on the tool bar.
From the displayed dialog box, select the type of new setup.
Press the OK button and you will now see the new setup in
the Setup List box.
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If a message window occurs after pressing the OK button
like that shown below,
you will have to create a default setup file by following this
procedure:
•
Select the permanent setup for the desired instrument
type.
•
Under the File menu select “Save setup to a file”.
•
In the “Save setup to a file” window type in “default”
under File name and select “Save”.
The new setup is now defined for a particular instrument ID,
and can be modified from the Setup List box. After creating
a new setup, you can store it to a disk file, or send it to the
824.
Renaming an Existing Setup
To rename an existing user defined setup, right click on the
setup in the left hand side of the screen and select Rename
Setup from the popup menu.
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Using the 824 Utility Software
10-15
A dialog box will be displayed to allow you to change the
name of the selected setup.
Enter the new name for the setup, and press the OK button.
NOTE: The permanent setup ID’s in the
824 cannot be renamed.
After renaming a setup, you can store it to a disk file, or send
it to the 824.
Deleting an Existing Setup
To delete an existing setup, right click on the user defined
setup in the left hand side of the screen and select Delete
Setup from the popup menu.
NOTE: This section applies only to
setups that exist on the 824. If a new
setup or a setup that is stored to disk is
deleted, this message will not appear.
WARNING!
10-16
Pressing the Delete Setup button will bring up a prompt asking if you are sure you want to delete the setup.
The setup will be deleted from the 824 and the Utility program.
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Locking and Unlocking Setups
To prevent accidently deleting a user defined setup, right
click on the desired setup and select Lock Setup from the
popup menu. Note that if you have just created a new setup,
the setup must first be stored to the 824 before it can be
locked.
Downloading Measurement Data
To display measurement data stored in the 824, select Download View from the View menu or hit the Download View
button from the tool bar.
All stored measurement information is retrieved from the
824 and displayed in the Download View window.
Pull down menu
First entry in list
shows the active
measurement
Measurement list
box
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Using the 824 Utility Software
10-17
Above the measurement list box is a pull down menu listing
the possible file types that can be displayed. This allows you
to select only the files you want for download. You can also
select “ALL <binary>” which will download all the files in
the 824 simultaneously for translation at a later date. If you
are selecting a specific file type such as “SSA” the measurement list box will show only SSA files.
The first entry in the Measurement list box displays information about the active measurement currently in the 824. Following the active measurement is a list of all other Data
Files stored in the 824.
The measurements are identified the same way the setups
were identified in the Setup List Box in the setup portion of
the 824 Utility manual.
The name of the ID is listed in the right hand column. For the permanent ID’s, this will be the Larson
Davis instrument type. For a user defined ID, this
can be anything that the user defines.
The three letter Larson Davis assigned name is
listed in the blue Ovals. This indicates the type of
instrument ID for which the setup was created.
The file number as stored in the 824.
Specifying a Destination File
You can tell the 824 Utility program where you want the
downloaded measurements to be stored. From the Download
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824 Reference Manual
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window, press the File folder button, next to the Directory
entry.
NOTE: The 824 Utility program will
download the files with the date the file
was created as the file name as a default.
It will also download the file to the 824
Utility Folder as a default. The option to
specify a file name and destination folder
is an optional selection, and is not
necessary for download.
2/6/17
A standard Windows file selection dialog box will appear.
Select the destination directory you wish.
Using the 824 Utility Software
10-19
Changing the Download File Name
To change the name of the downloaded file, enter a new
name in the “File name” area.
Press the Save button to return to the download section of
the 824 Utility software.
Our new file name and
the path to the
specified directory
now show on the
download screen.
These settings will
only apply for the
currently selected
measurement.
NOTE: This process will
have to be repeated for
each measurement to be
downloaded if you wish
to specify a file name and
destination folder for
each measurement. For
multiple file download,
each measurement will
use the file name as its
base name. For example,
if the file name is
“Roadtest” then the
download file will be
named
“Roadtest-
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824 Reference Manual
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Adding Notes to a download file
Information can be entered into the note fields provided for
each measurement. The information will be tagged onto the
translated reports for each measurements.
Selecting Active Measurements or Data Files
There are two types of measurements that can be downloaded. The first measurement in the list is the Active measurement, and is reported as Active Measurement on the tab
of the download windows. The other measurements are
stored as Data Files (on the 824), and will be reported as
such on the tab of the download window.
Active Measurement
Data file
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Using the 824 Utility Software
10-21
Downloading the Measurement
The 824 Utility software has
multiple file download capability by
selecting “ALL <binary>” from the
pull down menu and highlighting
one or more of the files from the
measurement list for download or
selecting files of one type and
highlighting one or more of the files
from the list.
To download a measurement, first select the file type from
the pull down menu. You may choose to view all of them
simultaneously by selecting “ALL <binary>” or you can
select the file type from the list. If you selected “ALL
<binary>”, highlight one or more of the files in the measurement list box and click the Download button. All the
selected files will be downloaded in their binary form.
Pull down menu
Measurement list
box
To get back to the setup screen press
the “setup” button on the toolbar.
10-22
If you selected files of the types (SSA, ISM, LOG, TAL,
FFT, or RTA) only this file type will be listed in the measurement list box. Select one or more of the files and click
the Download button. The following window will appear:
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2/6/17
Checking this box saves the
binary file in the 824 Utility
directory or the designated
directory.
Checking this box will launch
a program associated with
a.csv file or .txt file based on
the radio box selection. For
multiple file download, the
first file will be loaded into the
viewing program.
Allows selection of only the
records you are interested in
viewing.
The download window gives you the following options:
•
You can save only the binary data and translate the file
later, or
•
You can save the binary data and the selected records
from the translated file (saved as .csv or .txt), launch a
spreadsheet or text editor, or
•
You can save only the selected records from the translated file (saved as .csv or .txt) and launch a spreadsheet
or text editor.
Once you have selected the data viewing options, click on
the OK button to start the download process.
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Using the 824 Utility Software
10-23
The download status window will appear and report the status of the download.
The next file can now be selected, the destination folder
specified, the file name entered, and the data downloaded.
A downloaded file will be stored with
the file extension slmdl (Sound Level
Meter Down-load).
If you only selected “Save Binary Data” the downloaded file
must be translated by the 824 utility software to be viewable.
The first file in the measurement list
will be viewable in the spreadsheet
or text program. To view the other
records, they will have to be selected
and opened in the viewer program
from the directory where they are
stored.
If you selected “Save Binary Data” and “Launch Viewer of
Type” the Binary file will be saved and a spreadsheet program or text file program will automatically be opened.
If you selected only “Launch Viewer of Type”, the Binary
file will not be saved and a spreadsheet program or text file
program will automatically be opened.
Explanation of files in the 824 Utility Directory
In the 824 Utility directory (C:\ProgramFiles\LarsonDavis\824 Utility) you will notice 3 different types of files:
•
.slmdl (binary)
•
.csv (spreadsheet file)
•
.txt (text file)
The binary files for each virtual instrument (ISM, SSA,
LOG, RTA, FFT, AUD, TAL) have the following default file
designations:
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824 Reference Manual
2/6/17
28Jun15i.slmd
Designates which instrument type was used for
the measurement.
The default file name uses the date
on which the data was taken. The file
name can be changed to any name
that you choose.
•
28Jun15i.slmdl (ISM)
•
28Jun15s.slmdl (SSA)
•
28Jun15l.slmdl (LOG)
•
28Jun15r.slmdl (RTA)
•
28Jun15f.slmdl (FFT)
•
28Jun15a.slmdl (AUD)
•
28Jun15t.slmdl (TAL)
The translated files will have either a .csv extension or a .txt
extension depending on the choice made in the download
window.
Translating Data from a Downloaded Binary File
Selecting “Translate View” from the View Menu or pressing
the Translate button on the tool bar will display the Translation View.
You use the Translate view to select a downloaded file with
the file extension.slmdl to translate and view the desired
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Using the 824 Utility Software
10-25
records from the file on the screen, or to print the desired
records from the file.
The left portion of the Translate window functions as a Windows file tree. Select the folder that contains the downloaded measurement files that you wish to translate.
Locate the folder that contains the
downloaded file you wish to translate.
In this case we have found the downloaded file in the default location,
C:\Program Files\Larson Davis\824
Utility.
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Each downloaded file will contain several records, depending on the type of setup used, and the data stored.
Downloaded
measurement file.
Data translated from the
Downloaded file.
Selecting a Data set to view
After the downloaded file is located, click on the data you
wish to view.
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Using the 824 Utility Software
10-27
The data is displayed on the right side of the screen. If the
data record is too large to be effectively displayed in that
area, a message will appear at the top of the displayed record
indicating that it is available for export only.
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2/6/17
Printing a Translated File
To print the translated data, select the file that you wish to
print from the translate window . Display the file as
described earlier. Select Print from the File menu.
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Using the 824 Utility Software
10-29
The default Windows printer dialog box will be displayed.
The report will be printed in a text format similar to that
shown below.
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Viewing a Translated File Within a Spreadsheet Program
To view the translated data with a spreadsheet program,
select the View Data in Spreadsheet menu item from the
File menu or the Launch Spreadsheet button on the tool bar.
When you select the View Data in Spreadsheet menu item,
the 824 utility program will attempt to launch the program
associated with the .csv” file extension (comma separated
variables). If you have installed a spreadsheet program, your
Windows system will most likely have this file type linked
to that spreadsheet program.
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Using the 824 Utility Software
10-31
Once the data is in the spread sheet program it can be manipulated, stored, and graphed using the standard spreadsheet
functions.
You can also export and/or save the translated data to a text
file, by selecting the Export Data menu item from the File
menu.
Additional Features
Store Histograms for Overall and Interval Data
One of the features of the 824 Utility software is the ability
to store histograms in both the LOG and SSA virtual instruments for overall, interval, and daily data (LOG only).
These settings can only be made
from the 824 Utility software.
To store an interval histogram for the SSA instrument, select
SLM&RTA from the measurement list, click on the “Interval
tab” and check the box by “Store complete Histogram”.
NOTE: Storing interval or daily histograms for the LOG
instrument is done in a similar manner.
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Histogram Options Window
These settings only affect how the
data is displayed and not how they
are stored.
The histogram options window allows more flexibility in
viewing the histograms.
Here you can set the parameters to fit your particular needs.
To access the histogram options window, go under the
“View” menu item and select “Histogram Options”.
When viewing the histogram data,
the changes made in this window
will be immediately displayed.
The “Overall” area allows you to set the viewing parameters
for the overall SPL, Peak, and Unweighted Peak histograms.
The daily data is only available to
the LOG instrument.
The “Interval/Daily” column sets the parameters for displaying the SPL histogram for the interval period for either the
SSA or LOG instruments and also for the daily period data
for the LOG instrument.
NOTE: Storing the complete histogram for each interval and
daily record greatly reduces the number of events that can be
stored.
RT60 Select Options
The 824 Utility software can calculate an RT60 for each 1/3
octave frequency from the autostore ByTime data taken by
the RTA instrument.
The software gives you the flexibility to set the options for
the calculation and display of the RT60 values.
You must first take an autostore ByTime measurement.
Download the measurement and go to the Translate view
and select an RT60 report.
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Using the 824 Utility Software
10-33
Single click on a valid
RT60 report.
To change the RT60 calculated and displayed parameters, go
under the “View” menu item and select “Set RT60 Options”.
The following window will appear:
RT60 Measurements
Both the 824 instrument and the 824 Utility software round
the RT60 values to two decimal places. However, because
the 824 uses logarithmic arithmetic to calculate the RT60
value and the 824 Utility software uses double precision to
calculate the value, there may be small differences in the
values as reported by the 824 instrument and by the 824
Utility software.
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CHAPTER
11
RTA (optional)
Welcome to the System 824 Real-Time Analysis Firmware
Option. This option adds high speed spectral data gathering
to the System 824 and will enable you to perform the
following measurements:
•
•
•
•
•
Architectural Acoustics
On-board RT60 analysis
Room Criterion
Acoustic Impulse Event Analysis
Pass-by Event analysis
The 824 RTA option provides the following features:
•
•
•
•
•
•
•
RTA for fast spectral data
Performs room acoustics: RT60, RC, NCB, HTL
Averages any number of spectra
Uses measurement triggering for flexible acquisition
Autostores up to 400 spectra per second (one spectrum
every 0.0025 seconds)
Has both exponential and linear detectors
Direct printing of calculated RT60 for every 1/1 octave
or 1/3 octave band
Settings Menu
ROOMS.RTA is setup to be a 1/1
octave analyzer that takes 10 second
measurements for NCB and RC
analysis.
The Settings menu for the RTA instrument is accessed from
the S SETUP key. There are three permanent RTA
instrument definitions (ID) available: ROOMS.RTA, RT60A.RTA, and RT60-B.RTA.
RT60-A.RTA is set to be a 1/3 octave
analyzer for the measurement of RT60 with the room being excited with
pink noise.
To select an RTA instrument press the S SETUP key, scroll
down to RTA and press the c check key. The RTA Live
view will now be displayed. Press the S SETUP key again
to return to the SETUP menu. At the top of the Setup menu
“Edit Settings” will be highlighted. Press the c check key
to edit the RTA settings menu.
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RTA (optional)
11-1
RT60-B.RTA is set to be a 1/3 octave
analyzer for the measurement of RT60 with the room being excited with
impulsive noise such as from a
pistol, balloon pop, etc.
See chapter 5 of this Manual for more details on selecting
instrument IDs.
Minimum RT-60 Value
The minimum RT-60 which can be measured, also referred
to as the “Residual RT-60”, is a function of 1/3 octave
response time as shown in the following graph.
.
Hz
10
100
100
0
100
00
000
100 00
0
0
.
1
0.1
0.0
0.0
000
100
Seconds
Re sid u al RT-60
010
For other information pertaining to the RTA instrument, see
the following in this manual:
•
•
•
•
For data storage, see “Taking Measurements and Storing
Data” on page 4-5.
For printing RTA reports, see “Printing Reports” on page
8-2.
For I/O commands, see "Serial Port Interface Remote
Control" on page A-1
For RTA specifications, see “RTA Mode Specifications”
on page C-18.
The menu layout of the RTA settings is shown in the table
below:
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824 Reference Manual
2/6/17
Menu Items
Submenu
Title
Gain
(dB)
-20
-10
+0
+10
+20
+30
+40
+50
Bandwidth
1/1
1/3
Detector
Lin
Exp
Lin Detc Time
0.0025 to 99.9975 sec
Exp Detc Time
(seconds)
1/32
1/16
1/8
1/4
1/2
1
2
4
8
16
32
64
Exp Store Rate
1/2 second
1/8 second
Transducer
Condnsr
Electret
Direct
Random Corr
No
Yes
Autostore
No
Yes
Pretrigger #
0-400 samples
Save ByTime
No
Yes
Triggering
No
Yes
Trigger Source
Any 1/1 or 1/3 octave filter
Flat
Trigger
Setup
2/6/17
Available Settings
Options
User customized text entry
RTA
Autostore
Available Settings Options
RTA (optional)
11-3
Menu Items
Submenu
Arm
Trigger
Trigger
Setup
(continued)
End
Available Settings Options
Available Settings
Options
Arm Mode
Now
L<
L=
L>
Input
Time
Count
Arm Level
0.0 - 255.9 dB
Arm Time
00.0000 to 99.9975 sec
Arm Samples
0 - 65535
Arm Logic In
Low
High
Trigger Mode
Now
L<
L=
L>
Input
Time
Count
Trigger Level
0.0 - 255.9 dB
Trigger Time
00.0000 to 99.9975 sec
Trig Samples
0 - 65535
Trig Logic In
Low
High
End mode
Never
L<
L=
L>
Input
Time
Count
End Level
0.0 - 255.9dB
End Time
00.0000 to 99.9975 sec
End Samples
0 - 65535
End Logic In
Low
High
End Then
Stop
Repeat
Average
Repeat Count
0 - 255
Average Count
0-9
Then
Run on Input
11-4
No
Yes
824 Reference Manual
2/6/17
Menu Items
Submenu
Available Settings Options
Trigger
Setup
(continued)
Run Logic In
Low
High
Logic Out
0 - 65535
RT60 dB
Down
5
10
15
20
25
30
Auto RT60
No
Yes
Note
8 Characters
Available Settings
Options
Settings Descriptions
Title Setting
Use the title setting to create a title or heading for printed
reports. This title will be placed at the top of each RTA
report you print.
RTA Settings Menu
Gain Setting
Gain adjusts the voltage level delivered to the measuring
portion of the meter from the microphone and preamplifier.
Bandwidth Setting
Selects 1/1 or 1/3 octave filter bandwidth for real-time
analysis.
Detector Setting
Selects the averaging method to be used.
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RTA (optional)
11-5
•
•
Linear
Exponential
Linear Detector Time
The Linear Detector Time will be
adjusted to an integer multiple of
0.0025 seconds (2.5mS).
Allows the user to select the averaging time when the linear
detector is used. Also sets the storage rate for the Autostore
ByTime records.
•
0.0025 to 99.9975 seconds
Exponential Detector Time
When an exponential detector is selected, this parameter sets
the exponential decay time.
•
1/32 to 64 seconds
Exponential Store Rate
The Exponential Detector Time
multiplied by the Exponential Store
Rate gives the total Auto Store time.
Selects the rate at which spectral samples are output and
stored when the detector is exponential. The interval time,
time between successive samples, is equal to the exponential
detector time multiplied by the exponential store rate.
•
•
1/2
1/8
NOTE: For example, if the detector time is 1/8 and the store rate is
1/2, then the 824 would generate spectra samples at a rate of 16
times per second.
Transducer
When a condenser microphone is
used, the 824 requires a stabilization
time of approximately 45 seconds
before a measurement can be taken.
•
•
•
11-6
Condenser - This indicates that the microphone being
used is an air condenser type and the 824 will generate
the appropriate polarization voltage.
Electret - This indicates that the microphone being used
is an “Electret” (pre-polarized) microphone. The 824
will not generate any polarization voltage.
Direct - This indicates that no microphone is being used
and electrical signals are being injected directly into the
preamplifier. No polarization voltage is generated.
824 Reference Manual
2/6/17
Random Correction
The Random Corr setting gives you the option of turning on
a digital filter to provide the correction necessary to provide
a random incidence response when measuring with a 2540
or 377B41 free-field microphone.
See “Random Incidence Microphone
Correction” on page C-24 for the
random incidence correction filter’s
response.
No - Random incidence correction is turned off.
Yes - Random incidence correction is turned on.
Autostore Settings Menu
Autostore
When a linear detector is selected,
the store rate is that of the linear
detector.
Turns the Autostore function on or off. It allows the 824 to
measure and store basic information such as the Leq, Max,
and Min spectra when a measurement is ended by the
triggering setup or by pushing the run/stop key. When
Autostore is on, ByTime data is automatically stored in the
Autostore record if Save ByTime is set to Yes. For setups
with a linear detector, spectra are stored once every linear
detector time.
For setups with an exponential detector, samples are stored
every 1/256 of a second (0,004 second) to every 32 seconds.
When an exponential detector is
selected, samples are stored every
(exponential
detector
time)
multiplied by the (exponential store
rate).
By default, the RT60-A and RT60-B
instruments have Autostore and
ByTime enabled.
Pretrigger samples are only
available when the trigger function
is used to start the measurement.
2/6/17
Pretrigger #
Allows the user to select the number of pretrigger samples
that are stored with an Autostore ByTime record. The 824
keeps a circular buffer of the most recent 400 samples. The
RTA (optional)
11-7
buffer is reset every time a new run is started. The number of
spectra in the buffer is displayed in the Trigger Status view.
This setting determines how many of these spectra to copy
into the beginning of the Autostore record.
•
0 - 400 samples
Save ByTime
When Autostore is turned on, ByTime
records are automatically stored.
This feature allows the user to enable or disable storage of
ByTime data in an autostore record. With this feature turned
off and the Autostore function turned on, the 824 will only
store Leq, Max, and Min spectra.
Triggering
A typical trigger having the
following settings:
Trigger Source: 1 kHz
Arm Level: 80.0 dB
Arm Mode: L >
Arm Time: 2.0 second
would transition to arm after the 1
kHz filter level was greater than 80
dB for 2 seconds.
Turns triggering on or off. There are four parts to triggering:
Arm, Trigger, End, and Then. Arm and Trigger work in
tandem to create a two step trigger to start an Autostore. End
and Then work together to determine when to stop
measuring.
You can also set the trigger source
from the Trigger Status display by
moving the cursor to the desired
band, press the c check key and
select “Set Source” from the menu.
Allows the user to select a filter or flat overall level as a
trigger source.
Trigger Source
Arm Settings Menu
Arm Mode
Elapsed time and qualifying times
are evaluated only when a new
ByTime sample is created. This
causes the minimum effective time
resolution to become the same as the
update interval.
11-8
The 824 becomes armed when the following conditions are
met:
•
•
Now - The 824 will arm immediately.
L < - When the level is less than the “Arm Level” for the
“Arm Time”, then, the 824 will arm.
824 Reference Manual
2/6/17
“L” indicates the level of the filter
specified by the Trigger Source
setting.
•
•
•
•
•
L = - When the level is equal to the “Arm Level”, +/-0.5
dB, for “Arm Time” then the 824 will arm.
L > - When the level is greater than the “Arm Level” for
“Arm Time”, then, the 824 will arm.
Input - The 824 arms when the logic input line changes
to “Arm Logic In” state.
Time - The 824 arms after the “Arm Time” seconds in
the ready mode.
Count - The 824 arms after “Arm Count” samples of
data have been received.
Arm Level
Arm Time is used in conjunction with
Arm Level as a qualifier for the level
setting. See example below.
This trigger level is used when the “Arm Mode” is set to a
level state (L<, L=, L>). This level must be reached before
the 824 will arm.
•
0.0 - 255.9 dB
Arm Time
When the “Arm Mode” is set to Time, the “Arm Time” must
expire before the 824 will arm.
This is also a qualifier for the level settings. If the time is
non-zero, then the level condition must be met for the
specified time before Arm Mode is entered.
•
00.0000 to 99.9975 seconds
Arm Samples
When the “Arm Mode is set to Count; “Arm Samples” is the
number of samples that will be taken before the 824 is
armed.
•
0 - 65535
Arm Logic In
When the “Arm Mode” is set to Input, the 824 will arm
when the state of the Logic In line changes to this level.
Logic In is sampled 32 times each second.
•
•
2/6/17
Low
High
RTA (optional)
11-9
Trigger Settings Menu
Trigger Mode
The 824 triggers and starts recording an Autostore record
when Armed and the following conditions are met:
•
•
•
•
•
•
•
Now - The 824 starts recording an Autostore immediately.
L < - When the level is less than the “Trigger Level” for
“Trigger Time”, then, the 824 begins recording an Autostore.
L = - When the level is equal to the “Trigger Level”, +/0.5 dB, for “Trigger Time”, then, the 824 begins recording an Autostore.
L > - When the level is greater than the “Trigger Level”
for “Trigger Time”, then, the 824 begins recording an
Autostore.
Input - The 824 starts recording an Autostore when the
logic input line changes to “Trigger Logic In” state.
Time - The 824 starts recording an Autostore after “Trigger Time” seconds.
Count - The 824 starts recording an Autostore after
“Trig Samples” of data have been received.
Trigger Level
“L” indicates the level of the filter
specified by the Trigger Source
setting.
This level is used when the “Trigger Mode” is set to Level
(L<, L=, L>). This is the amplitude in dB at which the 824
will start recording an Autostore record. It must be valid for
the period of time set by “Trigger Time”.
•
0.0 - 255.9 dB
Trigger Time
When the “Trigger Mode” is set to Time, this is the time that
must pass before the 824 starts recording an Autostore
record. This is also a qualifier for the level settings. If the
time is non-zero, then the level condition must be met for the
specified time before the trigger will occur.
•
11-10
00.0000 to 99.9975 seconds
824 Reference Manual
2/6/17
Trig Samples
When the “Trigger Mode” is set to Count; “Trig Samples” is
the number of samples that will be taken before the 824
starts recording an Autostore record.
•
0 - 65535
Trig Logic In
When the “Trigger Mode” is set to Input, the 824 starts
recording an Autostore record when the logic input line
changes to the “Trig Logic In” state.
•
•
Low
High
End Settings Menu
End Mode
The measurement ends when the following conditions are
met:
•
•
•
•
•
•
•
Never - The measurement continues until the run/stop
key is pressed.
L < - When the level is less than the “End Level” for
“End Time”, then the 824 stops recording an Autostore.
L = - When the level is equal to the “End Level”, +/-0.5
dB, then the 824 stops recording an Autostore.
L > - When the level is greater than the “End Level” for
“End Time”, then the 824 stops recording an Autostore.
Input - The 824 stops recording an Autostore after the
logic input line changes to “End Logic In” state.
Time - The 824 stops recording an Autostore after “EndTime”.
Count - The 824 stops recording an Autostore after “End
Samples” of data have been received.
End Level
This level is used when the “End Mode” is set to Level (L<,
L=, L>). It is the amplitude in dB at which the 824 will stop
recording an Autostore record.
2/6/17
RTA (optional)
11-11
•
0.0 - 255.9 dB
End Time
If set to 0 seconds, triggering will
repeat
“forever”,
and
the
measurement will end when stopped
or out of memory.
The 824 stops recording an Autostore record when the “End
Time” has been satisfied.
•
00.0000 to 99.9975 seconds
End Samples
If set to 0 samples, the measurement
will stop after the first event is
captured.
The 824 stops recording an Autostore after “End Samples”
has been satisfied.
•
0 - 65535
End Logic In
When the “End Mode” is set to Input, the 824 stops
recording an Autostore record when the L logic In line
changes to “End Logic In” state.
•
•
Low
High
Then Settings Menu
End Then
After the measurement ends, the 824 may do the following:
Repeat Averaging requires the End
Mode to be set to Time or Count so
that all records are the same length.
•
•
Stop - The measurement ends.
Repeat - The measurement repeats when the Arm and
Trigger settings have been satisfied. A new Autostore
record is created for each repeated measurement.
•
Average - The measurement repeats (like repeat above)
except that the spectra are averaged with the preceding
spectra.
Repeat Count
Allows the user to select how many times the measurement
will repeat when the “End Then” setting is set to Repeat.
•
11-12
0 - 255
824 Reference Manual
2/6/17
Average Count
This is the number of times the measurement is repeated and
averaged when the “End Then” setting is set to Average.
•
0-9
Trigger
Settings Menu (continued)
.
.
Run on Input
When set to Yes the instrument will run when the logic input
line changes to the “Run Logic In” state.
•
•
No
Yes
Run Logic In
•
•
Low
High
Logic Out
The Logic Out bit value determines which lines (heater, cal,
or logic) will be used on the control connector to indicate
each of the five states.
•
These lines can be used to control
lights in a remote control device to
indicate the current state.
0 - 65535
The setting for the Output Logic state selection is combined
into one 15-bit setting that has 3 bits (one for each output
line-Logic Out, Heater Out, and Cal Out) for each of the five
states (Stop, Ready, Armed, Triggered, Ended).
Use the table below to determine how these will be set up.
Ended
Triggered
Armed
Ready
Stop
16384
8192
4096
2048
1024
512
256
128
64
32
16
8
4
2
1
Heat
Cal
Logic
Out
Heat
Cal
Logic
Out
Heat
Cal
Logic
Out
Heat
Cal
Logic
Out
Heat
Cal
Logic
Out
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RTA (optional)
11-13
The default setting indicates the
following:
Ended state is output on logic out.
Triggered state is output on logic
out.
Armed state is output on cal.
Ready state is output on heat.
Stop state is not output.
The default setting is 04768 which is shown by the bolded
squares in the table above.
The Logic output is on pin 2 of the control connector and
will be driven to +5 volts through a 1000 ohm resistor when
asserted or zero volts when not asserted. Pin 1 is the ground
signal.
The Cal output is on pin 7 of the control connector and will
be driven to +5 volts through a 10,000 ohm resistor when
asserted and to zero volts when not asserted.
For more information on the Control
Connector, see the section “System
824 Components” on page 1-8
The Heater control output is on pin 8 of the control
connector and will conduct current to ground when asserted
and not conduct when not asserted; uses an open drain ‘N’
channel transistor. Maximum voltage is +40 VDC and -0.5
VDC and the maximum current is 100 mA. Return current
path is through pin 1, control ground.
RT60 Reverberation Time Settings
RT60 dB Down
The automatic RT60 algorithm will search for a point 5 or
more dB down from the maximum sample and then
calculate an RT60 between that point and the next point,
“RT60 dB Down”.
Example: If “RT60 dB Down” is set to 30 dB, the RT60 will
be calculated for the data between 5 and 35 dB down from
the max. The available selections are:
•
•
•
•
•
•
5 dB
10 dB
15 dB
20 dB
25 dB
30 dB
Auto RT60
The Auto RT60 setting, when enabled, automatically
calculates the RT60 for each filter, on screen, as the user
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moves between filters using the up uand down darrow
keys.
Note
If Note ends with a numeral it will be
incremented automatically with each
spatial average snapshot taken or
stored.
An 8 character note field is provided to annotate a spatial
average. This is useful when describing the measurement
you are taking and keeping track of different measurements
or their location.
RT60-A and RT60-B Instrument Definition
The RT60-A Setup is configured for
the use of a steady-state noise source
which is shut-off to initiate the
decay. The RT60-B Setup is
configured for the use of a noise
burst such as a balloon bursting.
The System 824 contains two special RTA IDs on the setup
menu which will simplify making an RT60 measurement.
Both of these setups load the RTA instrument but with the
triggering, arm, and end menus configured for two types of
measurements.
The RT60-A and RT60-B RTA instruments are accessed
from the S SETUP key.
RT60-A
Although the settings are predefined
in RT60-A and RT60-B, they can be
changed at any time and used as
customized setups for a personalized
RT60 measurement.
2/6/17
The RT60-A setup is designed to gather data to measure an
RT60 by exciting a room with a steady state noise. It is
configured in the following way:
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Detector: Linear
Detector Time: 0.01 seconds
Autostore: Yes
PreTrigger: 50
Save ByTime: Yes
Triggering: Yes
Trigger Source: 1 kHz
Arm Mode: L >
Arm Level: 80.0 dB
Arm Time: 2.0 second
Trigger Mode: L <
Trigger Level: 80.0 dB
Trigger Time: 00.0000 seconds
End Mode: Time
End Time: 3.0 seconds
RTA (optional)
11-15
•
Then: Stop
RT60-B
The RT60-B setup is designed to measure an RT60 by
exciting a room with impulsive noise such as a gunshot or a
balloon popping and is configured in the following way:
•
•
•
•
•
•
•
•
•
•
•
•
Detector: Linear
Detector Time: 0.01 seconds
Autostore: Yes
PreTrigger: 10
Save ByTime: Yes
Arm Mode: Now
Triggering: Yes
Trigger Source: 1 kHz
Trigger Mode: L>
End Mode: Time
End Time: 3.0 seconds
Then: Stop
Qualifying Background Noise: Rooms [RTA] ID
This ID sets up the System 824 to
measure and evaluate background
noise according to the RC and NCB
room noise criteria.
The System 824 has an Instrument Definition that makes it
easy to measure room criteria, NCB and RC, using the RTA
in 1/1 octave bandwidth. The setup is configured to take data
for 10 seconds at each location in a room. Each
measurement is automatically stored in the Autostore
ByTime history.
ROOMS.RTA is configured in the following way:
•
•
•
•
•
•
•
•
•
•
11-16
Bandwidth: 1/1 octave
Detector: Linear
Linear Detector Time: 00.1000 seconds
Autostore: Yes
ByTime: No
Triggering: ON
Trigger Mode: Now
End Mode: Time
End Time: 10.0000 seconds
End Then: Stop
824 Reference Manual
2/6/17
Display Views
This next section will explain the various displays available
under the V View key. Once a measurement has been
taken, the 824 allows you to view the results and manipulate
the data.
RTA Views
The RTA Display Views are accessed through the
View key. To select the RTA Display Views press the
View key. The following menu will appear:
V
V
Now press therright arrow key to bring up the “View
RTA” display view menu.
Use the uup and ddown arrow
keys to highlight the desired display.
The RTA display view menu offers 5 choices: Live, Leq,
Max, Min, and Times. Use the c check key to select the
Live display.
2/6/17
RTA (optional)
11-17
Live
If the sample time is greater than
0.25 seconds a display spectrum is
generated and displayed to keep the
live data current. If the sample time
is less than 0.25 seconds, the display
still updates every 1/4 second.
The RTA Live display shows the live spectrum and is the
current sampled data with a sample time based upon the
detector, detector time and detector store rate settings. The
Live display is updated regularly when the 824 is running.
Display label
Current filter level in dB
Bandwidth (1/1 or 1/3 oct.)
Selected filter frequency
Live spectrum’s duration
1/1 octave cursor
Leq
Press the VView key again to
display the “View RTA” menu. Press
the uup and ddown arrow
keys to highlight the desired display
and press the c check key to select
the highlighted display.
The Leq display shows the equivalent level of all the
samples. A current or overall reset will reset the Leq.
Display label
Filter level in dB
Bandwidth (1/1 or 1/3 oct.)
Selected filter frequency
Leq spectrum’s duration
1/1 octave cursor
NOTE: Leq, Max, and Min are measured only while triggered, if
triggering is enabled. If triggering is disabled they are measured
while the 824 is running by pressing the s R/S key. If Autostore is
enabled, Leq, Max, and Min will be reset at every trigger (or run if
Triggering is off), otherwise they will accumulate for each R/S
measurement until manually reset.
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Max
The Max spectrum shows the maximum level obtained by
each filter and the maximum broadband (Flat) level. This is
a bin-by-bin maximum level. The Max spectrum is reset by
a current or overall reset and the R/S key when Autostore is
enabled.
Display Label
Filter level in dB
Bandwidth (1/1 or 1/3 oct.)
Selected filter frequency
Leq spectrum’s duration
1/1 octave cursor
Min
Once in a display view, you can
simply use the uup and ddown
arrow keys to move between the
views.
The Min spectrum shows the minimum level obtained by
each filter along with the minimum broadband (Flat) level.
This is a bin-by-bin minimum level. The Min spectrum is
reset by a current or overall reset and the R/S key when
Autostore is enabled.
Display label
Filter level in dB
Bandwidth (1/1 or 1/3 oct.)
Selected filter frequency
Leq spectrum’s duration
1/1 octave cursor
Times
The Times display shows the date and time when the overall
measurement began and the date and time when the last
measurement ended. These times are not affected by the
automatic reset or the manual “Current” reset, but are reset
2/6/17
RTA (optional)
11-19
with an “OverAll” reset. The total running time is also
displayed. This is the total elapsed time of all measurements
since the previous “OverAll” reset.
Display label
Overall start date and time
Overall end date and time
Overall runtime
Trigger Views
The Trigger Display Views are accessed through the V
View key. To select the Trigger Display Views press the
VView key. The following menu will appear:
Use the uup and
“Trigger”.
ddown arrow keys to highlight
Now press therright arrow key to bring up the “View
Trigger” display view menu.
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The Trigger display view offers 2 choices: Status and Setup.
Use the c check key to select the Status display.
Status
The Trigger status display shows the current state of the
RTA, showing either Stopped, Ready, Armed, Triggered, or
End. This display shows a copy of the Live spectrum and its
graph. Also displayed is the repeat count when set to repeat
or repeat with average, and the number of samples gathered
pre or post trigger.
=
Display label
Trigger State
Filter level in dB
Selected filter frequency
Trigger source frequency
Repeat count
No. of pretrigger or triggered
ByTime samples
Setup
Use the ddown arrow key to move
to the Setup display or press the
VVIEW key, highlight Setup and
press the c Check key.
2/6/17
The Trigger Setup display shows the trigger settings in an
interpretive way. Only applicable settings are displayed.
RTA (optional)
11-21
Shows that triggering is turned on
Display label
Arm conditions
Trigger conditions
End conditions
Repeat measurement 2 times
The interpretation of the Trigger Setup display is as follows:
•
•
Pressing the c Check key provides
quick access to the trigger settings.
•
•
The 824 will arm when the 1 kHz filter is greater than
80.0 dB for a period of 1 second.
When the level of the 1 kHz filter drops below 80.0 dB
for 0 seconds (immediately), the 824 is triggered and
begins taking a measurement.
The measurement continues until the End condition is
met which means that the level must drop below 50 dB
for 2 seconds.
The measurement will repeat 2 more times before stopping for a total of 3 measurements.
As the settings are changed the Trigger Setup display will
show the relevant settings in an easy to read form.
Autostore Views
If triggering is enabled, the record is
stored when the End condition is met
or when the s R/S key stops the
measurement. If triggering is not
enabled the record is stored when the
s R/S key stops the measurement.
An Autostore is a historical record of triggered data that is
stored automatically when the Autostore setting is set to Yes.
The Autostore includes summary data (Leq, Max, and Min
spectra) covering the entire duration of the Autostore and,
optionally, ByTime spectra. RT-60 analysis of the ByTime
spectral time history is also provided.
If you just came from the Trigger
Setup display, press the lleft
arrow key to back out to the main
VIEW menu.
The Autostore Display Views are accessed through the V
VIEW key. To select the Autostore Display Views, press the
V VIEW key and the u up and ddown arrow keys to
highlight “Autostore”. The menu will appear like this:
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824 Reference Manual
2/6/17
Now press therright arrow key to bring up the “View
Autostore” view menu.
Press therright arrow key to select the available
Autostore summary data views which are Leq, Max, and
Min.Use the u up and d down arrow keys to highlight
the desired display.
Press the c check key to view the Leq display.
Leq
The autostore Leq display shows a bin by bin equivalent
level of all samples while the Autostore is triggered.
2/6/17
RTA (optional)
11-23
Autostore occurrence date and time
Display label
Record number
Filter level in dB
Bandwidth (1/1 or 1/3 oct.)
Selected filter frequency
Autostore duration
Number of autostore records
To move to the next Autostore display, press the
key and then the rright arrow key.
c check
Max
The Autostore Max display shows the maximum level
obtained by each filter and the broadband maximum level of
all samples while the Autostore is triggered.
Autostore occurrence date and time
Display label
Record number/total records
Filter level in dB
Bandwidth (1/1 or 1/3 oct.)
Selected filter frequency
Autostore duration
Number of autostore records
Min
The Autostore Min display shows the minimum level
obtained by each filter and the broadband minimum level of
all samples while the Autostore is triggered.
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824 Reference Manual
2/6/17
Autostore occurrence date and time
Display label
Record number
Filter level in dB
Bandwidth (1/1 or 1/3 octave)
Selected filter frequency
Autostore duration
Number of autostore records
Pressing the c check key twice while in any of these
display views will toggle you between the Leq, Max, and
Min autostore displays.
The uup and ddown arrow keys will move you to the
next or previous Autostore records.
Press the V View key to return to the “View
Autostore”sub- menu.
Press the lleft arrow key to back out to the main “View
Autostore” menu showing Autostore, ByTime, and RT-60
menu items.
Use the d down arrow key to highlight the “ByTime”
menu item and press the rright arrow key to access the
“ByTime” menu and displays.
2/6/17
RTA (optional)
11-25
The following “View ByTime” menu appears:
Press the c check key to view the ByTime spectrums
recorded during the Autostore.
Autostore ByTime Spectral History
The Autostore ByTime spectral history has two displays for
viewing the time history data. The first is called the ByTime
Spectrum and the second is called the ByTime Graph.
ByTime Spectrum
The Autostore ByTime Spectrum display shows just one
sample in time and the entire frequency spectrum with
frequency on the horizontal axis.
Autostore record number
Display label
Current ByTime sample number
Filter level in dB
Total number of ByTime samples
Selected filter frequency
ByTime sample time
This ByTime display shows that 600
spectra were taken and we are
currently looking at record number
597.
11-26
With the uup and ddown arrow keys you can view
each ByTime spectrum sample that was recorded. Use the
lleft and rright arrows to move the cursor to look at
each individual frequency.
824 Reference Manual
2/6/17
To move to the ByTime Graph
display, press the c check key
twice.
NOTE: Notice as you move through each ByTime sample that the
sample time changes. A minus sign in front of the time indicates
that they are pretrigger samples. 0 is the point where the trigger
occurred.
ByTime Graph
The Autostore ByTime Graph display is a time graph of just
one filter frequency, plotted with time as the horizontal axis.
This graph is useful in seeing the level “rise or fall”
characteristics of each individual filter.
Autostore record number
Display label
Current ByTime sample number
Filter level in dB
Total number of Bytime samples
Horizontal graph scaling
Selected filter frequency
ByTime sample time
The uup and ddown arrow keys move you through
each filter. The lleft and rright arrow keys move to
the previous and next ByTime sample.
ByTime Spectrum Check Menu
As discussed earlier, in order to move between the ByTime
spectrum display and the ByTime Graph display you pressed
the c check key twice (toggling between the ByTime
Spectrum view and the ByTime Graph view). Pressing the
c check key once when viewing the ByTime spectrum
display puts you in the check menu. The check menu is
shown below:
2/6/17
RTA (optional)
11-27
The check menu offers the following options:
The Locate menu helps you find the
record you would like to view.
•
•
ByTime Graph - View the time graph of one filter
Autostore - View the Autostore Leq, Max, and Min
spectra
•
Locate an Autostore/ByTime record
- Next - The next Autostore record
- Prev - The previous Autostore record
- First - The first ByTime record
- Last - The last ByTime record
- Find - Finds the specified ByTime record
The Spatial Averaging displays and
menus are covered later in this
chapter.
•
Average - Add spectrum to spatial average or view spatial spectra average
If 1/3 octave filters are selected, the
Rooms display gives you the Hearing
Threshold Level or HTL for this
spectrum.
•
Rooms - View NCB and RC Room Criteria for this spectrum (for 1/1 octave filters)
Graph - Adjusts the graph scale and offset (See 824 Reference Manual)
•
- Graph Level -Allows numerical entry of graph
level in dB.
- Graph Scale - Allows numerical entry of graph
scale
ByTime Graph Check Menu
Pressing the c check key once when viewing the ByTime
spectrum display puts you in the check menu. The check
menu is shown below:
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824 Reference Manual
2/6/17
The check menu gives you the following options:
The Locate menu helps you find the
record you would like to view.
•
•
ByTime Spectrum - View the Bytime spectrum
Autostore - View the Autostore Leq, Max, and Min
spectrum
•
Locate an Autostore ByTime record
- Next - The next Autostore record
- Prev - The previous Autostore record
- First - The first ByTime record
- Last - The last ByTime record
•
- Find - Finds the specified ByTime record
Graph-V - Adjusts the vertical graph scale and offset
- Graph Level -Allows numerical entry of graph
level in dB.
•
- Graph Scale - Allows numerical entry of graph
scale
Graph-H - Adjusts the horizontal graph scale
Press the uup and ddown arrow keys to
adjust the horizontal scale factor.
2/6/17
RTA (optional)
11-29
Press the c check key to exit.
RT-60
The RT-60 display is accessed by pressing the V View key
and highlighting “Autostore”. The menu appears like this:
Press the rright arrow key to bring up the “View
Autostore” display view menu.
Highlight “RT-60” and press the c check key.
RT60
The RT-60 analysis display uses the ByTime history to
calculate a room decay time. This time is calculated from the
cursor position to a point a number of dB down as set by the
“RT60 dB Down” setting and then extrapolated to a drop of
60 dB using a “Least Squares” slope calculation method.
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824 Reference Manual
2/6/17
RT-60 time in seconds at frequency shown
Display label
Current ByTime sample number
RT-60 dB down setting
RT-60 delta time
Horizontal graph scaling
Selected filter frequency
ByTime sample time
Total number of ByTime samples
The uup and ddown arrow
keys move you to the next higher and
lower filter frequency. The lleft
and rright arrow keys move you
to the previous and next ByTime
sample.
An auto-select routine will automatically locate the cursor to
be 5 dB below the maximum level. The auto-select is
executed on demand from the check menu and the first time
the RT-60 display is selected. There is a vertical line for the
cursor specifying the beginning of the measurement and a
horizontal line drawn at the dB down level.
If auto RT60 is set to “Yes”, the
auto-select routine will be performed
whenever a new filter is selected.
Auto-select also sets the horizontal zoom so that the whole
decay fits on screen.
RT60 Check Menu
Pressing the c check key when viewing the RT60 display
puts you in the RT60 check menu. The check menu is shown
below:
2/6/17
RTA (optional)
11-31
The horizontal graph adjustment,
(Graph-H), provides a useful feature
that allows you to view a large
amount of time data in the ByTime
Graph view. A scale factor of 1 to
1024 can be selected. A scale factor
of greater then 1 will cause multiple
pieces of time data to be graphed to
1 bar. The measured data can be
viewed by pressing the lleft or
rright arrow keys. The cursor
will not move to the next graph point
until the selected number of data
points
have
been
displayed
numerically. This facility allows up
to 1024 numeric data points to be
displayed for each graph cursor
point and allows the user to observe
an overall shape of the measured
data on screen without the need for
scrolling.
The check menu offers the following options:
•
•
•
•
•
•
RT60 dB Down - dB down setting for RT-60 calculation
Auto RT60 - Setting to enable an auto-select of RT60
whenever a new filter is selected
Auto-Select - Auto-Select cursor position
Graph-V - See page 2-13 for explanation
Graph-H - See page 2-13 for explanation
View Back - Returns you to the previous display
Spatial Avg Views
The Spatial Averaging facilities allow user selected spectra
to be averaged on an equal weighting basis. It is often used
to average the spectra that were measured at various
locations around a noise source or across the length of a wall
or partition. The resulting average is displayed and can be
stored into a history for later viewing.
The Spatial Avg Display Views are accessed through the V
View key. To select the Spatial Avg Display Views press the
V View key and highlight “Spatial Avg”. The following
menu will appear:
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824 Reference Manual
2/6/17
Now press therright arrow key to bring up the “View
Avg” display view menu.
The “View Avg” display view menu offers 2 choices: Spatial
Avg and Avg History. Use the c check key to select the
Spatial Avg display.
Spatial Avg
The “Spatial Avg” display shows the spectra which have
been currently averaged.
Display label
Bandwidth (1/1 or 1/3 oct.)
Selected filter frequency
Spatial averaged sample count
*Annunciator or note
Spatial averaged spectrum
NOTE: *If the right digit of the annunciator is numeric then it will
auto-increment with each spatial average store operation from the
check menu.
Any display which shows a spectrum
can be averaged using the
“+Average” item on its check menu.
Each display that can show a spectrum has a check menu
item, “+Average”, that, when selected, will prompt the user
“Add to Average?”. It then offers the following choices:
•
2/6/17
Yes -averages the spectrum being viewed to those previously averaged.
RTA (optional)
11-33
There is effectively no limit on the
number of spectra that may be
averaged.
•
•
No - the spectrum is not averaged into the previous average but the spatial average display is shown
Cancel - nothing happens and the previous display is
shown
Once, one or more spectra have been averaged, they can be
stored into the “Avg History”.
Spatial Avg Check Menu
The Spatial Avg check menu is shown below:
To access the check menu simply press the
when in the “Spatial Avg” display.
c check key
The check menu offers the following options:
The 824 will prompt you to reset the
“Spatial Avg” buffer. This does not
reset the “Avg History”.
•
Note- Note is used to describe this average which is to be
stored to the Avg History
•
•
•
•
•
•
Store - Store Spatial Average in Spatial Average History
Reset - Resets the Spatial Average buffer
Avg History - View the Spatial Average History
Rooms - View Room Criteria for this spectrum
View Back - Return to the previous display
Graph - Adjusts the vertical graph scale and offset
Avg History
If the data being viewed has come
from a stored file, the +average
function is not available and will
beep instead of bringing up the
prompt “Add to Average?”.
11-34
The Avg History display shows a history of the spatial
averages which have been stored using the “Store” function
in the “Spatial Avg” check menu. Use the V View menu or
the “Spatial Avg” check menu to access the “Avg History”
display.
824 Reference Manual
2/6/17
Occurrence date and time
Display label
Current average history record number
Level in dB of selected filter
Bandwidth (1/1 or 1/3 oct.)
Selected filter frequency
Number of spectra averaged
Spatial average history note field
Total number of spatial average history records
In order to clear the “Avg History”
records, an overall reset is required.
Use the uup and ddown arrow keys to move to the
previous and next spatial average history records.
To manipulate the “Avg History” records, press the
check key to access the “Avg History” check menu.
c
Avg History Check Menu
The “Avg History” check menu is shown below:
The check menu offers the following options:
•
•
Edit Note - Edit the note of this stored record.
Locate - Locate a Spatial Avg history record
- First - The first Spatial Avg history record
- Last - The last Spatial Average history record
- Find - Finds the specified Spatial Average history record
2/6/17
RTA (optional)
11-35
If you are viewing an “Avg History”
record use the +average function to
average records which are already in
the average history together.
Remember that all records are
weighted equally. If you have an
average history record which was
comprised of 100 samples it will be
averaged as one record.
•
•
•
•
+Average - Add spectrum to spatial average
Rooms - View Room Criteria for this spectrum
View Back - Return to the previous display
Graph - Adjusts the vertical graph scale and offset
Rooms Views
NCB and RC are calculated and
displayed from any spectral display
including snapshot or Averaged
Spectrum and are accessed from
their individual check menus.
The Rooms Views are accessed from the check menu of
every display that can show a spectrum.
The Rooms displays consist of RC, NCB and HTL. All these
measurements are based on ANSI S12.2-1995.
The NCB and RC Criteria for 1/1 octave data calculates the
following:
•
•
•
•
•
SIL - speech interference level
Pass/Fail on Rumble check
Pass/Fail on Hiss check
Mid-frequency average Lmf and RC
Neutral, Hiss, Rumble or Vibration/Rumble check
RC, NCB and HTL are accessed in the “Rooms” display
from any spectrum’s check menu.
NCB and RC are only displayed
when using 1/1 octave filters.
Rooms NCB
The Rooms NCB display calculates the noise criterion for
the spectrum being displayed when “Rooms” is chosen from
any spectrum check menu.
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Display label
Level in dB of selected filter
Selected filter frequency
Room level in dB
Room data
NCB status
NCB curve line, an annoyance or loudness spectrum indication
The “NCB status” indicator can show the following:
•
•
•
•
Under - indicates that SIL (speech interference level) is
under the defined range for NCB
Over - indicates that SIL is above the defined range for
NCB
(H) - indicates the NCB Hiss check failed
(R) - indicates the NCB Rumble check failed
Rooms RC
Use the uup and ddown arrow
keys to move between the RC and
NCB displays.
The Rooms RC display calculates the noise criterion for the
spectrum being displayed when “Rooms” is chosen from a
check menu.
Display label
Level in dB of selected filter
Selected filter frequency
Room midfrequency average level
Room data
RC status
RCB line, fixed slope annoyance or interference
The “RC status” indicator can show the following:
•
•
•
•
2/6/17
Under - indicates that Lmf (mid frequency average
level) is under the defined range for RC
Over - indicates that Lmf is above the defined range for
RC
(N) - indicates the RC is Neutral
(RV) - indicates the RC Vibration/Rumble check failed
RTA (optional)
11-37
•
(R) - indicates the RC Rumble check failed.
Rooms HTL
The “Rooms HTL” display is only
available when 1/3 octave filters are
selected.
The Rooms HTL display calculates the Hearing Threshold
Level for the spectrum being displayed when “Rooms” is
chosen from any spectrum’s check menu.
Display label
Level in dB of selected filter
Selected filter frequency
HTL status
The “HTL status” indicator can show the following:
•
•
11-38
Pass - indicates the recording environment is suitable to
produce recordings without audible background noise
Fail - indicates the recording environment is NOT suitable to produce recordings without audible background
noise
824 Reference Manual
2/6/17
CHAPTER
12
FFT (Optional)
The FFT option gives the 824 the ability to do narrow band
frequency analysis using the Fast Fourier Transform. This
chapter describes the features and functions of this option.
Features
The FFT option has the following features:
•
•
•
•
•
•
•
•
400 line FFT (1 Hz to 20 kHz)
Hanning, Flat-Top or Rectangular window
Bandwidths of 200Hz, 500Hz, 1kHz, 2kHz, 5kHz,
10kHz, and 20kHz
Count averaging (1 to 16384)
Snapshot data storage (no ByTime autostore)
Display zoom with a factor of 2, 4, or 8
Total Harmonic Distortion
User defined Linear Units
Settings Menu
The Settings menu for the FFT instrument is accessed from
the SETUP S key.
To select the FFT instrument, press the SETUP S key,
scroll down to the FFT instrument and press the Check c
key. The FFT display will appear. Press the SETUP S key
again to return to the SETUP menu. At the top of the Setup
menu “Edit Settings” will be highlighted. Press the Check
c key or the right rarrow key to edit the FFT settings
menu.
2/6/17
FFT (Optional)
12-1
NOTE: See “System 824 Virtual
Instruments” on page 6-1 for a more
detailed explanation on selecting
instrument definitions.
12-2
The menu layout of the FFT settings is shown in the table
below:
Menu Items
Available Settings Options
Title
User customized text entry
Gain
(dB)
-20
-10
+0
+10
+20
+30
+40
+50
Bandwidth
(Hz)
200
500
1k
2k
5k
10k
20k
Avg Count
1 to 16384
Repeat
No
Yes
Window
Rectngl
Hanning
Flt-top
Overload Skip
No
Yes
Transducer
Condnsr
Elctret
Direct
Random Corr
No
Yes
Linear Units
4 characters of text
Linear Scale
-128.99 to 127.99
Auto Snapshot
No
Yes
824 Reference Manual
2/6/17
Settings Descriptions
Title Setting
Use the title setting to create a title or heading for printed
reports. This title will be placed at the top of each FFT report
you print. You are allotted 30 characters. Printing of FFT
reports is not currently available.
Gain Setting
-20 & -10 dB gain are achieved by
desensitizing the microphone by
reducing its polarization voltage
from 200 volts to 20 volts. See “Gain
Setting - (SSA)” on page 7-6 for
more details.
The gain setting sets the measuring range of the instrument
in 10 dB steps by adjusting the amplification of the
microphone signal. This setting provides the following
options:
-20, -10, 0, +10, +20, +30, +40, +50
Bandwidth
The frequency resolution for each
line is the bandwidth divided by the
lines setting. With the bandwidth set
to 20kHz and 400 lines, the
frequency resolution is 50 Hz/line.
The frequency range of a baseband FFT analysis extends
upwards from zero to a selected maximum frequency. Thus,
the bandwidth, or the frequency range covered by the
analysis, can range from a maximum of 20kHz to a
minimum of 200Hz. This setting provides the following
options:
200Hz, 500Hz, 1kHz, 2kHz, 5kHz, 10kHz, 20kHz
The following table shows resolution and FFT calculation
times as a function of the frequency bandwidth.
2/6/17
Bandwidth, Hz
200
500
1k
2k
5k
10k
20k
Resolution, Hz/line
0.5
1.25
2.5
5
12.5
25
50
Calcuation Time, Seconds
0.50
0.20
0.10
0.05
0.02
0.01
0.05
FFT (Optional)
12-3
Avg Count
The 824 FFT is guaranteed to have
no more than 75% overlap.
The average count is the number of FFTs taken and averaged
together.
•
1 to 16384
FFT Repeat
Once the average count is completed you can choose to
continue repeating the FFT or have the FFT stop.
•
•
No - Stops the count when the average count has been
reached.
Yes - Repeats the count continuously.
Window
The Hanning window is typically
used for most measurements.
The time weighting window can be the following:
•
•
•
Rectangular; provides finest frequency resolution.
Hanning; good compromise between amplitude accuracy
and frequency resolution. Most commonly used for
general measurements.
Flat-top; provides best amplitude accuracy. Often used
for calibration.
The Rectangular window provides the best frequency
discrimination but can have significant filter leakage or
effects of a truncated series. The Hanning window
minimizes the filter leakage with the cost of a wider main
lobe. The Flat-top window gives better amplitude accuracy
in the passband.
Overload Skip
Overload skip allows you to throw away or keep spectra that
contain overloaded data.
•
•
12-4
No - Averages in spectra with overload data.
Yes - Does not average spectra in that contains
overloaded data.
824 Reference Manual
2/6/17
Transducer
When a condenser microphone is
used, the 824 requires a stabilization
time of approximately 45 seconds
before a measurement can be taken.
•
Gains of -20 and -10 dB are only
available
for
condenser
microphones.
•
•
Condenser - This indicates that the microphone being
used is an air condenser type and the 824 will generate
the appropriate polarization voltage.
Electret - This indicates that the microphone being used
is an “Electret” (pre-polarized) microphone. The 824
will not generate any polarization voltage.
Direct - This indicates that no microphone is being used
and electrical signals are being injected directly into the
preamplifier. No polarization voltage is generated. This
is the choice when using an accelerometer as the
transducer
Random Correction
The Random Corr setting gives you the option of turning on
a digital filter to provide the correction necessary to provide
a random incidence response when measuring with a freefield microphone.
See “Random Incidence Microphone
Correction” on page C-24 for the
random incidence correction filter’s
response.
No - Random incidence correction is turned off.
Yes - Random incidence correction is turned on.
NOTE: Random incidence correction can be used with the
2540, 377B41 and 2551 microphones.
Linear Units
If this field is left blank then no
linear value will be displayed. See
the section “Displaying Amplitude in
Linear Units” on page 12-13 for
more details.
Four characters of text are provided so the user can enter the
type of units being used for the measurement. It accepts any
alphanumeric character that can be found by scrolling with
the up uand down darrow keys.
Linear Scale
Allows you to enter the sensitivity of a transducer in
decibels relative to volts.
•
2/6/17
-128.99 to 127.99
FFT (Optional)
12-5
Auto Snapshot
This feature allows you to automatically capture an FFT
Snapshot on the completion of each FFT. If Repeat is set to
“Yes”, then it creates a pseudo Time History. The time
interval between spectra Snapshots will equal the FFT
calculation time (see “Bandwidth” on page 12-3) multiplied
by the number of counts selected for Count Averaging. For
more detail on Snapshots, see “Snapshot” on page 12-10.
FFT Display
The FFT data displays are accessed through the View V
key. To select the FFT displays press the View V key. The
following menu will appear:
“FFT” accesses the live FFT
spectrum and “Snapshot” displays
the FFT snapshot data.
With “FFT” highlighted, press the Check c key to enter the
FFT display.
FFT
The FFT display shows a live FFT spectrum.
Display label
Level at cursor
Selected filter frequency
Count avg
12-6
824 Reference Manual
2/6/17
The left land right rarrow keys move the cursor to
change the frequency and level displayed.
FFT Zoom
You can view approximately 80 bars
of the FFT at once. When you are
zoomed out you will notice that each
bar represents several frequencies or
lines. Pressing the right rarrow
key moves to the next line. The
cursor will not move to the next bar
until it shows all of the lines
represented by that bar of the graph.
The FFT zoom on the 824 allows you to view a
representation of all 400 lines or a portion of the 400 lines on
the display. This is called a display zoom.
The up uarrow key will zoom in the display by a factor of
2 to 8. This means that a zoom factor of 2 shows one half of
the 400 lines on the display. A zoom factor of 8 would show
one eighth of the 400 lines on the display. The down
darrow key zooms out to a full screen display of the FFT.
The zoom factor is shown graphically as a horizontal bar at
the bottom of the bar graph. The shorter the bar, the greater
the zoom.
The location of the zoom bar indicates the position of the
displayed area of the spectrum.
NOTE: When more than one frequency is
represented by a single bar, the largest
bar is represented on the display. As you
press the right and left arrow keys to
move the cursor across the display, you
will notice that the cursor does not move
until all of the frequencies represented by
that bar have been displayed.
Overall representation
of spectrum
(No zoom)
Some examples of zoomed displays are shown below:
Zoomed three to one
Cursor indicates 3
points on graph
Zoomed two to one
Cursor indicates 2 points
on graph
Cursor indicates 5 to 6
points on graph
Zoomed one to one
Bar shows one to one
zoom, meaning cursor
indicates one point on
graph
While zoomed, the display will scroll when the cursor nears
either the left or right edge of the display.
2/6/17
FFT (Optional)
12-7
FFT Check Menu
Pressing the Check c key while in the “FFT” display puts
you in the check menu shown below:
The check menu offers the following options:
The THD as calculated in the 824
satisfies all of the requirements for
ANSI S3.6.
•
Store Snapshot - Stores the current FFT spectrum at that
moment in time.
•
THD - Activates the THD display which shows the
calculated THD.
Settings - Activates the FFT settings menu.
Graph - Adjusts the vertical graph scale and offset (See
824 Reference Manual)
•
•
- Graph Level - Allows numerical entry of graph
level in dB.
- Graph Scale - Allows numerical entry of graph
scale
THD (Total Harmonic Distortion)
The THD display shows the results of the THD calculations.
Fundamental frequency
THD+n dB down
Harmonic dB down
THD+n percentile
Harmonic percentiles
4th & higher harmonic
percentile
12-8
4th & higher harmonic
824 Reference Manual
2/6/17
THD information is only available
on screen at the time of the
measurement and is not stored with a
file or printed to a report.
Results are reported in dB down difference and units of
percentile. The dB down difference is calculated by
subtracting the harmonic level from the fundamental level.
The percentage is equal to one hundred times ten raised to
the power of the result of the dB down difference divided by
twenty.
Entering the THD display will autoposition the cursor to the
fundamental frequency on the FFT
screen.
THD is calculated by scanning the full spectrum to find the
fundamental frequency and selecting the highest peak. The
actual frequency is extrapolated from the fundamental bin
frequency and the highest sideband bin frequency. The
second harmonic is found by doubling the fundamental
frequency, then finding the nearest bin frequency and
summing its level with it’s side-band levels. The third
harmonic is found by tripling the fundamental frequency,
then finding the nearest bin frequency and summing its level
with it’s side-band levels. The fourth and higher harmonics
are found by the process described above for the second and
third harmonics.
THD+n is calculated by summing the energy of the
fundamental bin with the five bins on each side, then
subtracting the energy sum of all the other levels.
For THD to be calculated, the following criteria must be
met:
•
•
•
•
•
2/6/17
The window must be in Hanning mode after an overall
reset. If not, “Available only in Hanning Window” is
shown.
The fundamental must be above the 4th bin or 10 Hz
whichever is higher. In the case where the fundamental
frequency is near the 5th bin and it’s skirt extends into
some or all of the first four bins, the fundamental energy
sum calculation will include only the 3rd and/or 4th bins
but not the 1st or 2nd bin. In any case the noise energy sum
calculation will never include the first four bins.
The fundamental must be higher than any of the first four
bins. There must not be excessive DC or near DC levels.
THD+n must be at least 10 dB below the fundamental
level. There must be an identifiable tone.
The fundamental frequency will be displayed whether
there is an identifiable tone or not.
FFT (Optional)
12-9
•
•
If a harmonic is less than 10 dB above the noise floor, the
level of the harmonic is marked with an asterisk. The
noise floor is calculated as the maximum of the
minimum in the two adjacent valleys.
If one of the harmonic side-bands is higher than the
harmonic then the harmonic is marked with an asterisk.
THD Check Menu
Pressing the Check c key while in the “THD” display puts
you in the check menu. The check menu is shown below:
The check menu offers the following options:
The bandwidth for each line is the
bandwidth setting divided by the
lines setting.
•
View FFT - Takes you back to the FFT display
•
Bandwidth - Allows you to reduce the frequency
bandwidth from 20kHz to 200Hz. This setting provides
the following options:
200Hz, 500Hz, 1kHz, 2kHz, 5kHz, 10kHz, 20kHz
Snapshot
Once you have stored an FFT snapshot by accessing “Store
Snapshot” from the FFT check menu, you can view the
snapshot data by pressing the View V key. The following
menu appears:
12-10
824 Reference Manual
2/6/17
Highlight “Snapshot” and press the Check c key to access
the snapshot data.
Date and time
Snapshot number/
total number
of snapshots
Use the up uand down
each record.
darrow keys to scroll through
Use the check menu to control the HORIZONTAL SCALE.
The date and time records when the snapshot was taken.
Snapshot Check Menu
To access the snapshot check menu, press the Check c key
while viewing the snapshot data. The following menu
appears:
The check menu offers the following options:
•
2/6/17
Locate Snapshot record
FFT (Optional)
12-11
- First - The first Snapshot record
- Last - The last Snapshot record
•
- Find - Finds the specified Snapshot record
Graph - Adjusts the graph scale and offset (See 824
Reference Manual)
- Graph Level - Allows numerical entry of graph
level in dB.
•
•
- Graph Scale - Allows numerical entry of graph
scale.
Zoom in - Allows you to see FFT spectrum with more
detail. (See page 6 for more information)
Zoom out - Allows you to see FFT spectrum with less
detail. (See page 6 for more information)
FFT Calibration
The FFT spectrum always displays the measured level in
decibels on a logarithmic scale. In fact, the use of the term
“level” implies a decibel value relative to a defined
reference value.
Acoustic measurements are in dB
relative to 20 µPa
When the System 824 has been calibrated using an acoustic
calibrator, whether from the ISM, SSA, LOG or FFT
instrument, the decibel levels are relative to 20 µPa (20
micro-Pascal).
Note, however, that it is possible to provide a digital readout
of the amplitude at the cursor position in linear units as
shown below in the section “Displaying Amplitude in Linear
Units” on page 12-13
Calibrating dB to a Different Reference
For measurements of non-acoustical parameters such as
acceleration, it is more appropriate to express the
measurement in decibels relative to a different reference
using units typical for that parameter. This is easily done
using a calibrator to excite the transducer to a known value.
12-12
824 Reference Manual
2/6/17
The decibel level of a measured parameter is calculated as
follows:
Lv = 20Log10[V/Vref]
where V = measured parameter
and Vref = reference value, same units as the measured
parameter
Calibrating to measure acceleration
in decibel units relative to an
acceleration unit (e.g. g, m/s2, ft/s2,
etc.)
For example, if we prefer to express acceleration in units of
“g”, we may select to represent the “acceleration level” in
decibels relative to 1 µg. Using an accelerometer calibrator
which excites the accelerometer at an rms amplitude of 1 g,
such as the PCB 394C06 Portable 1g Handheld Shaker, we
will perform a calibration and calculate that the level we
measure should be
Lv = 20Log10[1.0/(1.0 X 10 -6)] = 120 dB.
Thus, prior to performing the calibration using the
calibration item in the Tools menu, we set the Cal. Level to
120.
Similarly, should we wish to use the same calibrator to
measure in units of dB relative to 1 µm, we would set the
Cal. Level to
Lv = 20Log10[9.86/(1.0 X 10 -6)] = 139.9 dB
Displaying Amplitude in Linear Units
Providing a digital readout of the
measured amplitude at the cursor
position in linear units.
Although the measured level is always displayed in decibels
on a logarithmic scale with a digital readout at the cursor
position in dB, a second digital readout can be created which
will show the amplitude in linear units. This is particularly
useful when using an accelerometer and desiring to readout
the amplitude in units such as g, m/s2, ft/s2, etc.The accuracy
of the linear units value will be +/- 5 % of the true value.
This procedure requires evaluating the sensitivity of the
transducer in decibels relative to volts. The sensitivity of the
transducer is usually provided in the manufacturers
2/6/17
FFT (Optional)
12-13
specifications. To convert sensitivity to decibels use the
following formula:
When the linear scale is set to zero
the 824 will read the rms input
voltage.
Linear Scale (dB) = 20Log (1 volt / sensitivity)
Obtaining a readout in units of “g”.
Example: The sensitivity of an accelerometer is typically
provided in units of V/g. Using an accelerometer having a
sensitivity of 50 mV/g, the Linear Scale would be calculated
as follows:
+26.0 dB = 20Log [1 volt / 0.05V]
The following table gives some examples of some typical
Linear Scale values for common accelerometer sensitivities.:
Sensitivity
Linear Scale (dB)
Units
100 mV/g
20 dB
g
50 mV/g
26 dB
g
25 mV/g
32 dB
g
10 mV/g
40 dB
g
5 mV/g
46 dB
g
14.0 mV/Pa
37.08 dB
Pa (2540)
44.5 mV/Pa
27.03 dB
Pa (377B41)
11.7 mV/Pa
38.64 dB
Pa (2559)
47.5 mV/Pa
26.47dB
Pa (377A60)
Obtaining a readout in units other
than “g”.
If the desired linear units are different from those provided
by the manufacturer, m/s2 for example, calculate the
sensitivity in those units, Volt/m/s2, and use that value in the
equation for Linear Scale.
Setup of Linear Units Readout.
The items to be defined to implement this feature are
“Linear Units” and “Linear Scale” which appear in the FFT
12-14
824 Reference Manual
2/6/17
Edit Settings menu as shown in “Settings Menu” on page
12-1 and on the screen as shown below.
Linear Units
Linear Units is simply 4 alphanumeric characters defining
the units name as it will appear on the screen.
Linear Scale
Linear Scale is the value of Linear Scale calculated as shown
in the preceding sections.
Input the desired values for both Linear Units and Linear
Scale by highlighting the item, pressing the Check c key,
entering the values and pressing the Check c key again to
close the menu.
Below is an example of the FFT live display with linear
units:
Standard dB level at cursor
Linear amplitude
Linear Units
Frequency shown by cursor
The following explains each of the display’s components:
In this case it shows 20.12 milli-g
acceleration.
2/6/17
Standard dB level at cursor - This is the dB display which
appears whether or not the linear amplitude is displayed.
FFT (Optional)
12-15
Read out at cursor - This is the linear units level at the
cursor.
NOTE: The units level is displayed in engineering
exponential notation.
Linear Units - This is the unit entered by the user in the
menu for “Linear Units”. In this particular case we have
entered “g” for acceleration.
Frequency shown by cursor - This is the frequency as
shown by the cursor.
NOTE: The linear units level is
displayed in engineering exponential
notation. This notation expresses the
exponent with a single character: “n”
–9
–6
for nano ( 10 ), “  ” for micro ( 10 ),
–3
“m” for mili ( 10 ), a space for no
3
exponent, “k” for kilo ( 10 ), “M” for
6
9
mega ( 10 ) and “G” for giga ( 10 ).
Frequently Asked Questions Concerning FFT
What is the reference level for decibels (dB) levels in the FFT option of the 824?
The decibel levels displayed by the FFT option of the 824
are the same as those for SPL in other instruments such as
SSA or ISM and is 20 micro-Pascal (set during your
microphone calibration process). Now, that may not mean
much if you are viewing the output of an accelerometer
rather than a microphone. The linear units are available to
view the output of the accelerometer but the dB level may be
of use.
To calibrate the dB level to some usable value for
acceleration requires the use of an accelerometer calibrator.
We use the PCB 394C06 Portable 1g Handheld Shaker. Set
the calibration level to something like 140dB and run
through the calibration procedure. Then the 824 FFT will
read 140 dB when it is excited with 1g. This provides a
reference of 0.1 micro-g (also 1 micrometer per second
squared).
12-16
824 Reference Manual
2/6/17
How do I get the DNA software to read FFT data in linear units.
To get DNA to read FFT data in a linear unit such a g or m/s
the data must be converted from the decibel numbers that
DNA receives from the 824 to that linear units value. To do
this you need to know a reference level for the decibel
reading that the 824 provides. It will change depending on
the current calibration offset in the 824. The answers to the
next two questions will help you accomplish this
calculation.
How can I convert decibels (dB) levels from the FFT option of the 824 into linear units
in my spreadsheet?
There are two ways to calculate the linear units from
decibels.
Method 1
With the FFT instrument in the 824 the data can be outputted
to the display in linear values such as 'g' (gravity), or meters/
second, volts or Pascal. The 824 makes this calibration using
a setting that the user enters. This setting is the sensitivity of
the unit relative to 1 volt and entered in dB into the Linear
Scale setting (for example a 50mv/g accelerometer would
have a Linear Scale of 20 LOG(1/0.05) or +26.02dB). The
Linear Unit setting is a text field so that the units may be
annunciated as desired.
The Linear Value is calculated in this way:
1. Take the dB reading
2. Subtract off the calibration offset (this makes the number
bigger since the cal. offset is negative)
3. Subtract 167 dB from the previous result and the number
is now in dB volts
4. Add the Linear Scale setting
5. Divide by 20
6. Take 10 to this power, this is the Linear Value
2/6/17
FFT (Optional)
12-17
Here is an example:
The calibration offset is -45.41dB
The Linear Scale is +26dB (for a 50mV/g accelerometer)
The FFT displays a level of 121.7dB and 20.17g linear value
1. 121.7dBTake the dB reading
2. 121.7-(-45.41)=167.11dBSubtract calibration offset
3. 167.11-167=0.11dBVsubtract 167dB (180-13, dB volts)
4. 0.11+ 26 = 26.11dBgAdd the Linear Scale setting
5. -26.11/20 = 1.3055divide by 20
6. 10^1.3055 = 20.21gtake 10 to this power (result will be
close to the FFT display)
The difference (+0.2%) between the 824 display and this
calculation are primarily due to the precision of math done
in the 824 versus precision of the math functions in the
calculator.
Method 2
Take any FFT display reading that shows a dB and a linear
level directly from the 824 display.
Calculate the linear reference level (what linear level gives
0dB) using this formula:
R = L / (10^(D/20))
where R is the linear reference level for the current
calibration settings of the measurement,
where L is the linear level displayed (i.e. g or m/s), and
where D is the decibel level displayed.
12-18
824 Reference Manual
2/6/17
Here's an example. I have an 824 connected to a signal
generator supplying 0.5 volts RMS, the Linear Units setting
is "g" and the Linear Scale setting is "-26.00" dB. I run the
824 FFT for a while and press stop, the display now shows a
dB level of 121.7dB and a linear level of 50.87 milli-g.
R = L / (10^(D/20))
R =.05087g / (10^(121.7dB/20))
R =.05087g / 10^(6.085)
R =.05087g / 1216186
R = 4.182748 x 10^-8
now use this R as the reference to get the readings in linear
units from dB like this:
L = R * 10^(D/20)
L = 4.182748g x 10^-8 * 10^(121.7dB/20)
L = 4.182748g x 10^-8 * 10^(6.085)
L = 4.182748g x 10^-8 * 1216186
L = 0.05087g
Another example, this time down 20 dB:
L = 4.182748g x 10^-8 * 10^(101.7dB/20) = 5.087 x 10^-3 =
.005087g
How can I manually enter a calibration offset so that the decibel levels (dB) from the
FFT option of the 824 are relative to 1 micro-meter per second squared?
The calibration offset is calculated with this formula (±5%
accurate):
LCAL = 20 log(4.467 nanovolts / Vref)
Where LCAL is the calibration offset being calculated, Vref
is the desired reference voltage (the voltage that would read
2/6/17
FFT (Optional)
12-19
0 dB) and 4.467 nanovolts is a constant set by the 824's
electronic design (4.467x10-9).
Example: It is desirous to display 140dB for 1 g due to the
relationship that 1 g is 10 meters per second squared (m/s2)
and 1 micrometer per second squared (mm/s2) is a common
reference level. Given that an accelerometer with a
sensitivity of 0.1V/g has a sensitivity of 0.01 volts per meter
per second squared (10 mV/m/s2). The voltage at 1 mm/s2
would be 0.01 microvolt (calculated ratio-metrically since
1m/s2 outputs 0.01V then 1m m/s2 will have an output of
0.01mV).
LCAL = 20 log(4.467 nV / 0.01mV) = 20 log(0.4467) = 7.00dB
LCAL is stored with these steps for instruments that have
firmware version 4.065 or newer:
Press the TOOLS key
Highlight Calibration and press the right arrow key
On the Calibration menu scroll to the bottom of the list and
highlight Advanced
Press the right arrow key to open the Advanced calibration
menu
Highlight the ----Secure---- line and press the check key, this
will change the Cal Level value setting to a special key value
of 224.48 that allow the calibration settings to be entered
directly (the key is to prevent accidental calibration
alteration)
Highlight the CAL Offset setting line and press the check
key
Enter the LCAL value calculated above and press the check
key
Highlight the ----Secure---- line again and press the check
key, this will change the Cal Level value setting back to
114.00 and secure the calibration settings.
12-20
824 Reference Manual
2/6/17
Exit the menu by pressing the power key, pressing the left
arrow or pressing TOOLS
For firmware versions prior to 4.065 the calibration offset
(LCAL) is entered using a computer and the following steps.
LCAL is then entered via computer by these I/O commands
using HyperTerminal:
Command: "S1,1"Response: ""// Overall Reset
Command: "S 41,225.48"Response: ""// Key, unlock the
S227 command
Command: "S227,-7"Response: ""// Send LCAL, enter your
LCAL value
Command: "Q227"Response: "
verify your LCAL value
-7.00"// Verify LCAL,
Command: "S 41,114"Response: ""// Restore Calibrator
Level
Here are typical Calibration Offset Levels (dB) for several
accelerometer sensitivities (re. 1mm/s2):
Sensitivity1mV/g10 mV/g100 mV/g1 V/g10 V/g
Cal. Offset 23.00 dB13.00 dB-7.00 dB-27.00 dB-47.00 dB
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FFT (Optional)
12-21
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CHAPTER
13
AUD (Optional)
The System 824 precision sound level meter with the 824AUD firmware option is the heart of the Larson Davis audiometer calibration system. This instrument and its firmware
maintain and exceed the performance of previous Model
800B-based systems when used with the AUDit™ software.
However, the System 824 with 824-AUD firmware alone
still possesses numerous analysis features useful for audiometer testing tasks such as:
•
•
•
•
•
•
•
•
Level
Frequency
Linearity
Total harmonic distortion
Pulse measurements
Crosstalk
Frequency modulation
Narrow band, broad band and speech noise
Some of these tests are slightly more tedious when
performed manually. The following overview of the 824AUD instrument should be augmented by familiarizing
yourself with the 824 Reference Manual.
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AUD (Optional)
13-1
Connecting the Test System
For performing audiometric calibration measurements,
connect the components as shown below.
Weight
Audiometer
System 824
Audiometer
Earphone
Artificial Ear
Microphone Preamplifier
The microphone is threaded into a connection inside the
artificial ear and the microphone preamplifier is inserted into
the opening on the side of the artificial ear base and threaded
into place. A microphone extension cable connects the
microphone preamplifier to the input of the System 824.
One of the audiometer earphones, connected to the
audiometer via a cable (not visible here), is placed on top of
the artificial ear and then the weight is placed on top to hold
it firmly in place.
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2/6/17
Selecting the 824-AUD Operation Mode
To enable the 824 audiometer testing firmware option, turn
on the 824.
After the start screen is appears, press S SETUP and use
the arrow keys up/down arrows ud to highlight the
AudTest.AUD setup (or your customized AUD setup).
Press the check key c to retrieve the AudTest.AUD setup.
The Linearity FFT display will appear.
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AUD (Optional)
13-3
Microphone Sensitivity Calibration
Press the VIEW key V
to open the View Menu.
Highlight SLM/RTA and press the check key c to obtain
the SLM+RTA Live screen shown below.
A more detailed description of the
calibration procedure can be found
in the section “Turning On and
Calibrating the System 824” on page
4-1.
This screen shows the third octave spectrum. In this
example, the measurement is reset and the cursor is placed
on the 1000 Hz third octave frequency. At this time, the
instrument should be calibrated manually.
Press the Tools key T, use the down
darrow key to
highlight “Calibration”, press the check key c twice, use
the down darrow key to highlight “Change” and press
the check key c. Follow the prompts to perform the
calibration.. Please refer to the 824 Reference Manual for
information on calibrating the instrument.
AUD Modes
There are three measurement modes for the AUD
instrument:
•
•
•
13-4
SLM+RTA  used to measure 1/3 octave spectra and
broadband weighted SPL.
FFT  used to measure constant bandwidth narrow
band spectra with special functions to perform attenuator
linearity, frequency flatness and harmonic distortion
measurements.
Pulse/FM  used to measure pulse and frequency
modulation functions of the audiometer.
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The mode is controlled by the display being shown. The
View menu is divided into three sections for the three modes
and can be used to select the display needed for a particular
measurement. Most of the displays are also grouped together
and alternately accessed by pressing the up uand down
darrow keys.
View Menu
The structure of the View menu is described below. Press the
VIEW key V to open the View Menu.
SLM/RTA Submenu
Highlighting SLM/RTA and pressing the right arrow key
rwill produce the SLM+RTA Submenu.
FFT Submenu
Highlighting FFT and pressing the right arrow key rwill
produce the FFT Submenu.
Pulse/FM Submenu
Pulse/FM has no submenu. Pressing he right arrow key
rwill produce the Pulse/FM - a display screen.
The display screens associated with these menus will be
described in detail in the following sections.
Display Sequence
The primary displays are grouped together and will cycle
through the following in sequence by pressing the down
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AUD (Optional)
13-5
arrow key d(the up arrow key u
displays in the opposite order):
Note: The FFT Display mode can be
accessed from the VIEW menu or
from the THD check menu. See
“FFT Display” on page 24 for
details on this display type.
•
•
•
•
•
•
•
will sequence these
SLM+RTA Live
Any Level-a, Any Level -b
Linearity RTA
Linearity FFT (activated by default when AUD is
activated)
Flatness FFT
THD
Pulse/FM
SLM+RTA Live Display
The SLM+RTA Live display provides a display of the realtime fractional octave spectrum. To access this display, press
the VIEW key V to obtain the display shown below.
Then select the SLM/RTA with the up/down arrows ud
and press the check key c. This will produce the
SLM+RTA Live Display shown below.
The right and left arrow keys control the filter cursor.
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The check menu (accessed by pressing the check key c
while this display is active) provides the setting choices
shown in the next two screen shots.
SLM+RTA Live Check Menu
The SLM+RTA Live check menu items are:
•
•
•
•
•
Graph -Allows control over the resolution and scaling of
the spectrum graph.
Gain -Changes the gain setting of the instrument.
Generally use 0dB gain for levels at 70dB SPL and
above, and 30dB gain for levels less than 70dB SPL. The
Auto Gain Control (AGC) function of the linearity
displays step between 0 and 30 dB gain, if the gain
setting is something other than 0 or 30 the AGC function
is inhibited.
RTA Detector -This setting controls the rate of change
of RTA filter output, Slow or Fast, which provides 1
second or 1/8th second exponential time constants,
respectively.
Bandwidth -The fractional octave bandwidth of 1/1 or 1/
3 are selected with this setting.
RTA Weighting -This setting selects either A, C or Flat
frequency weighting as a filter prior to fractional octave
filtering.
To measure the level in dB (re. 20 micro Pascals), place the
cursor on the frequency of interest and read the frequency
and value on the left hand side of the screen. Levels must be
corrected by using coupler/earphone RETSPLs and
microphone or other such corrections to arrive at the dB HL
value.
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AUD (Optional)
13-7
Several
different
linearity
measurements can also be performed
as described in “Linearity RTA
Display” on page 13-9, “Linearity
FFT Display” on page 13-13and
“Flatness FFT Display” on page 1317.
Linearity evaluation can easily be performed by placing the
cursor on the audiometric presentation frequency, then
varying the hearing level output and monitoring the
measured level on the 824.
Similarly, cross talk measurements are performed with the
non-test earphone being measured, then comparing the test
earphone level to that measurement.
Any Level -a, -b and -c Displays
The Any Level Displays -a, -b and -c are accessed from the
SLM+RTA Live display by pressing the down arrow key
d
The Any Level -a display, shown below, displays Flat
weighted broadband SPL values for Fast and Slow
simultaneously.
The Any Level -b display, shown below, displays the Fast
SPL for A, C and Flat frequency weightings simultaneously.
Frequency is also available on the
FFT mode displays using a more
stable FFT frequency calculator.
13-8
Both the -a and -b displays show the output of the frequency
counter, showing Frequency and Period. The frequency
counter is a hardware count based on zero crossing;
significant amplitude is needed to ensure an accurate
reading.
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The Any Level -c display, shown below, displays the Slow
SPL, Leq and SEL for the selected frequency weightings
and the peak level with its frequency weighting.
Use the right and left arrow keys to step between the -a, -b
and -c displays.
Press the check key c to access the check menu, shown
below.
Any Level Check Menu
The Any Level check menu items are:
•
•
Gain -Changes the gain setting of the instrument.
Weighting -This setting selects either A, C or Flat
frequency weighting for the sound level meter and FFT
(not used by the Any Level displays).
Linearity RTA Display
The Linearity RTA display can also
be accessed from the View Menu as
shown in “View Menu” on page 135.
2/6/17
The Linearity RTA display, shown below, is accessed from
the Any Level a and b Displays by pressing the down arrow
key d.
AUD (Optional)
13-9
The Linearity RTA display shows the level of the highest
fractional octave RTA data relative to a set reference level.
Also shown are the filter frequency of the selected level and
the RTA Bandwidth setting. The frequency weighting set by
the RTA Weighting setting is used; Flat by default. For
testing attenuator linearity at 1 kHz, it is recommended to
use A weighting to reduce low frequency ambient noise that
my be coupled into the microphone.
Set the reference level to the current level by pressing the
check key c. This will open the Linearity RTA check menu,
shown below.
Highlight “Set Reference” and press the check key c
again.
The reference can also be set to an absolute level using the
"Reference Lvl" setting on the check menu.
Once the reference has been set the level is shown relative to
the reference level as shown below.
This display is used to measure the attenuator linearity of an
audiometer. The highest amplitude fractional octave RTA
bin is found and displayed in the lower left corner of the
display. The chosen reference level is displayed in the lower
right corner.
This display has a manual and an automatic filter lock
feature to lock to the desired filter frequency when going to
low amplitudes when other noise signalsambient noises
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824 Reference Manual
2/6/17
or vibrations present in the environmentmay be higher
than the signal being output by the audiometer. The right and
left arrow keys control the lock mode. Press right once to
manually lock to the current frequency; a lock icon will
appear. Press the left arrow key once to activate the
automatic lock mode, a diamond shaped icon will appear.
Auto Icon
The lock mode will step in sequence from unlocked to
manual locked to automatic and back to unlocked with the
right arrow. The left arrow will sequence through the modes
in the reverse order.
Manual Lock
For manual operation select unlock while at a high
amplitude (70dB HL or above) where the highest amplitude
filter can be detected easily. When the correct frequency is
displayed press the right arrow to manually lock the filter so
that it does not change when measuring low amplitudes.
AGC is not active in the manual unlock or lock modes.
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AUD (Optional)
13-11
Automatic Lock
For automatic operations select the auto mode by pressing
the left (or right) arrow key until the diamond icon appears
as shown below.
Auto Icon
A trigger level setting is found on the check menu that
defines the amplitude below which the lock is set. When
above the trigger level the filter frequency will track the
highest amplitude signal. When the level of that filter drops
below the trigger level the lock is activated and the filter
frequency is unchanged. The icons will show this condition
with the lock and diamond icons as shown below.
Auto-Lock
Note: To change to another filter in auto mode, just increase
the amplitude until the level is above the trigger level.
When in automatic mode the Automatic Gain Control will
be activated. When the gain is set to 0dB, it will be changed
to +30dB when the signal is more than 45dB below the
overload level for 1.5 seconds. When the gain is set to
+30dB, the gain will be changed to 0dB whenever the
instrument becomes overloaded or the level is within 8dB of
the overload level for 1.5 seconds. The instrument will beep
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824 Reference Manual
2/6/17
once when the gain is changed automatically to 0dB and
twice when it is automatically changed to +30dB.
Linearity RTA Check Menu
Press the check key c to open the Linearity RTA check
menu, shown below.
The Linearity RTA check menu contains the following
items:
•
•
•
•
•
Set Reference -Set the reference level to the current
level, i.e. zero the display.
Reference Lvl -Reference level setting that may be
entered manually.
Gain -Changes the gain setting of the instrument.
Generally use 0dB gain for levels at 70dB SPL and
above, and 30dB gain for levels less than 70dB SPL. The
Auto Gain Control (AGC) function of the linearity
displays step between 0 and 30 dB gain, if the gain
setting is something other than 0 or 30 the AGC function
is inhibited.
RTA Weighting -This setting selects either A, C or Flat
frequency weighting as a filter prior to fractional octave
filtering.
Trigger Level -The Trigger Level setting defines the
level below which the automatic frequency lock becomes
active.
Linearity FFT Display
The Linearity FFT display can also
be accessed from the View Menu as
shown in “View Menu” on page 135.
2/6/17
The Linearity FFT display, shown below, is accessed from
the Linearity RTA display by pressing the down arrow key
dto produce the display shown below.
AUD (Optional)
13-13
.
Fundamental minus Reference
Reference Frequency
Fundamental Level
Reference Level
The Linearity FFT display shows the relative level of the
highest FFT bin and the true frequency of the input signal
derived from FFT data. The frequency weighting selected by
the Weighting setting is used, A by default, to offer reduced
out of band noise influence.
This display is used to measure the attenuator linearity of an
audiometer. The highest amplitude FFT bin is found and its
level is displayed in the lower left corner of the display. The
chosen reference level is displayed in the lower right corner.
A precise measurement of the frequency is displayed to the
center right of the display. If the level is greater than the
trigger level setting the THD plus noise value will be
displayed in the upper right corner.
To set the reference level to the current level first press the
check key c to display the check menu shown below.
Then highlight "Set Reference" and press the check key c
once more. The reference can also be set to an absolute level
using the "Reference Lvl" setting on the check menu. This
zero level may be set at the 70dB HL point as a reference.
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824 Reference Manual
2/6/17
Once the reference has been set the level is shown relative to
the reference level as shown below.
This display has a manual and an automatic filter lock
feature to lock to the desired filter frequency when going to
low amplitudes where other noise signalsambient noises
or vibrations present in the environmentmay be higher
than the signal being output by the audiometer. The right and
left arrow keys control the lock mode. Press right once to
manually lock to the current frequency; a lock icon will
appear as shown below.
Lock Icon
Press the left arrow key once to activate the automatic lock
mode, a diamond shaped icon will appear. The lock mode
will step in sequence from unlocked to manual locked to
automatic and back to unlock with the right arrow. The left
arrow will sequence through the modes in the reverse order.
Manual Lock
For manual operation select unlock while at a high
amplitude (70dB HL or above) where the highest amplitude
filter can be detected easily. When the correct frequency is
displayed press the right arrow to manually lock the filter so
that it does not change when measuring low amplitudes.
AGC is not active in the manual unlock or lock modes.
Automatic Lock
For automatic operations select the auto mode by pressing
the left (or right) arrow key until the diamond icon appears.
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AUD (Optional)
13-15
A trigger level setting is found on the check menu that
defines the amplitude below which the lock is set. When
above the trigger level the filter frequency will track the
highest amplitude signal. When the level of that filter drops
below the trigger level the lock is activated and the filter
frequency is unchanged. The icons will show this condition
with the lock and diamond icons.
Note: To change to another filter in auto mode, just increase
the amplitude until the level is above the trigger level.
When in automatic mode the Automatic Gain Control will
be activated. When the gain is set to 0dB, it will be changed
to +30dB when the signal is more than 45dB below the
overload level for 1.5 seconds. When the gain is set to
+30dB, the gain will be changed to 0dB whenever the
instrument becomes overloaded or the level is within 8dB of
the overload level for 1.5 seconds. The instrument will beep
once when the gain is changed automatically to 0dB and
twice when it is automatically changed to +30dB.
Linearity FFT Check Menu
Press the check key c to open the Linearity FFT check
menu, shown below.
The Linearity FFT check menu contains the following items:
•
•
•
13-16
Set Reference -Set the reference level to the current
level, i.e. zero the display.
Reference Lvl -Reference level setting that may be
entered manually.
Gain -Changes the gain setting of the instrument.
Generally use 0dB gain for levels at 70dB SPL and
above, and 30dB gain for levels less than 70dB SPL. The
Auto Gain Control (AGC) function of the linearity
displays step between 0 and 30 dB gain, if the gain
setting is something other than 0 or 30 the AGC function
is inhibited.
824 Reference Manual
2/6/17
•
•
Weighting -This setting selects either A, C or Flat
frequency weighting as a filter prior to FFT filtering.
Trigger Level -The Trigger Level setting defines the
level below which the automatic frequency lock becomes
active.
Note: The Linearity FFT display when using A or C
weighting should not be used to measure frequency response
and is not good to use for absolute amplitude measurement.
Always zero the display at your reference point and use the
relative level to see changes in amplitude relative to that
reference. Note also that the FFT's A and C weighting filters
may have up to ±0.2dB variation compared to the FFT Flat
weighting (due to component variations and tolerance).
Flatness FFT Display
The Flatness FFT display can also
be accessed from the View Menu as
described in “View Menu” on page
13-5.
The Flatness FFT display, shown below, is can be accessed
from the Linearity FFT display by pressing the down arrow
key d.
The Flatness FFT display shows the relative level of the
highest FFT bin, the true frequency of the input signal
derived from the FFT data and the THD plus noise metric.
The frequency weighting for this display is forced to Flat
regardless of the Weighting setting.
This display is used to measure the frequency response of an
audiometer. The highest amplitude FFT bin is found and its
level is displayed in the lower left corner of the display. The
chosen reference level is displayed in the lower right corner.
A precise measurement of the frequency is displayed to the
center right of the display. If the level is greater than the
trigger level setting the THD plus noise value will be
displayed in the upper right corner.
2/6/17
AUD (Optional)
13-17
The example display shown above is for a measurement at
1kHz. Measurements at 8kHz and 125Hz would appear as
shown below.
The operation and menus for this display are the same as
Linearity FFT; please refer above for operation instructions.
THD Display
The THD display, shown below, is accessed from the
Flatness FFT display by pressing the down arrow key d
.
THD+n percentile
Fundamental frequency
THD+n dB down
Harmonic
percentiles
Harmonic dB down
4th & higher harmonics
4th and higher percentiles
The THD display provides harmonic distortion
measurements of an audiometer and its phones. The FFT
capabilities of the 824 are used to measure the fundamental
13-18
824 Reference Manual
2/6/17
level, fundamental frequency and harmonics. THD data is
output in dB down from the fundamental level and in
percent. The display also shows the level and frequency of
the fundamental. An asterisk following a THD percentage
indicates that influences of system noise floor are present.
Results are reported in dB down difference and units of
percentile. The dB down difference is calculated by
subtracting the harmonic level from the fundamental level.
The percentage is equal to one hundred times ten raised to
the power of the result of the dB down difference divided by
twenty.
Entering the THD display will autoposition the cursor to the
fundamental frequency on the FFT
screen.
THD is calculated by scanning the full spectrum to find the
fundamental frequency and selecting the highest peak. The
actual frequency is extrapolated from the fundamental bin
frequency and the highest sideband bin frequency. The
second harmonic is found by doubling the fundamental
frequency, then finding the nearest bin frequency and
summing its level with its side-band levels. The third
harmonic is found by tripling the fundamental frequency,
then finding the nearest bin frequency and summing its level
with its side-band levels. The fourth and higher harmonics
are found by the process described above by summing the
energy of these harmonics.
THD+n is calculated by summing the energy of the
fundamental bin with the five bins on each side, then
subtracting the energy sum of all the other levels.
The THD as calculated in the 824
satisfies all of the requirements for
ANSI S3.6.
For THD to be calculated, the following criteria must be
met:
•
•
•
2/6/17
The window must be in Hanning mode after an overall
reset. If not, “Available only in Hanning Window” is
shown.
The fundamental must be above the 4th bin or 10 Hz,
whichever is higher. In the case where the fundamental
frequency is near the 5th bin and it’s skirt extends into
some or all of the first four bins, the fundamental energy
sum calculation will include only the 3rd and/or 4th bins
but not the 1st or 2nd bin. In any case the noise energy sum
calculation will never include the first four bins.
The fundamental must be higher than any of the first four
bins. There must not be excessive DC or near DC levels.
AUD (Optional)
13-19
•
•
•
•
THD Check Menu
THD+n must be at least 10 dB below the fundamental
level. There must be an identifiable tone.
The fundamental frequency will be displayed whether
there is an identifiable tone or not.
If a harmonic is less than 10 dB above the noise floor, the
level of the harmonic is marked with an asterisk. The
noise floor is calculated as the maximum of the
minimum in the two adjacent valleys.
If one of the harmonic side-bands is higher than the
harmonic then the harmonic is marked with an asterisk.
Press the check key c to open the THD check menu. This
menu contains the following items.
•
•
•
View FFT -View the current FFT spectrum.
Gain -Changes the gain setting of the instrument.
Generally use 0dB gain for levels at 70dB SPL and
above, and 30dB gain for levels less than 70dB SPL. The
Auto Gain Control (AGC) function of the linearity
displays step between 0 and 30 dB gain, if the gain
setting is something other than 0 or 30 the AGC function
is inhibited.
Bandwidth -Setting to select the FFT bandwidth,
choices are include 200, 500, 1k, 2k, 5k, 10k and 20k
Hertz. The default is 10kHz. If the THD of signals with
fundamental frequencies above 2500Hz is to be measure,
choose a Bandwidth of 20kHz so that the 2nd through
4th harmonics are captured.
Pulse/FM Display
The Pulse/FM displays provide measurements to qualify the
pulsed amplitude and frequency modulation (FM) response
of an audiometer.
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824 Reference Manual
2/6/17
There are two Pulse/FM displays. The Pulse/FM-a display,
shown below, is accessed from the THD display by pressing
the down arrow key d
The Pulse/FM-b display is obtained by pressing the right
arrow key.
The left and right arrow keys left or right arrow lrcan
be used to toggle between the Pulse/FM-a and the Pulse/FMb displays.
Pulse/FM-a Display
The Pulse/FM-a display shows all the required values for the
calibration of the pulsed tone capabilities of an audiometer.
Present the pulsed tone at a proper level and press the RUN/
STOP key s. The stability of the measurement can be
evaluated visually. To retrieve data, press RUN/STOP again
s and read the values from the screen.
The following values are displayed: rise time, fall time, on
time, off time, plateau duration, in milliseconds, as well as
overshoot in dB.
See Figure 13-1 on page 13-22 for
greater clarification of the values
displayed.
•
•
2/6/17
Rise Time (B-C) - time in milliseconds between the -20
dB point (referred to the maximum level) and -1 dB point
on the rising edge of the pulsed signal envelope,
nominally between 20 and 50 ms
Fall Time (E-G) - time in milliseconds between the -1
dB point and -20 dB point on the falling edge of the
pulsed signal envelope, nominally between 20 and 50 ms
AUD (Optional)
13-21
•
“ xxxx ” indicates that the On/Off
level ratio is greater than 20 dB.
•
•
•
On Time (J-K) - time in milliseconds between
successive -5 dB points of the envelope of the pulsed
signal during which the signal is present, nominally
between 190 and 260 ms
Off Time (F-J)) - time in milliseconds between
successive -5 dB points of the envelope of the pulsed
signal during which the signal is absent, nominally
between 190 and 260 ms
Plateau or Pulse Width (C-E) - duration in milliseconds
of the plateau during which the signal is within -1 dB of
its nominal value
Overshoot (Lov) - the level in dB that the signal rises
above the normal “ON” level (SPL on).
Figure 13-1 Pulse
13-22
Parameters
824 Reference Manual
2/6/17
Pulse/FM-b Display
This screen displays required values for the calibration of
the frequency modulated tone capabilities of an audiometer.
Present the frequency modulated tone at an appropriate level
and press the RUN/STOP key s.
When the “stable” message is displayed, as shown below,
press RUN/STOP s again and read the values from the
screen.
The following values are displayed, all in units of Hz:
•
•
•
•
Pulse/FM Check Menu
Carrier frequency
Maximum frequency
Minimum frequency
Modulation rate
While in either the Pulse/FM-a screen or Pulse/FM-b screen
the check menu can be accessed by pressing the check key
c.
This menu contains the following items.
•
2/6/17
Gain -Changes the gain setting of the instrument.
Generally use 0dB gain for levels at 70dB SPL and
above, and 30dB gain for levels less than 70dB SPL.
AUD (Optional)
13-23
•
High Pass Wght -This setting enables the high pass
filter section of the A or C weight filters which provide
low frequency noise reduction while measuring pulses or
FM signals; can be set to Flat weighting also. The default
is A weighting high pass.
FFT Display
The FFT display will show the FFT spectrum. This display,
shown below, is activated via the VIEW menu, Press VIEW
key V, highlight FFT and press check key c.
It can also be activated from the THD check menu. The right
and left arrow keys control the frequency cursor and the up
and down arrow keys control the display horizontal zoom
feature.
FFT Check Menu
Press the check key c to open the FFT check menu. This
menu contains the following items.
•
•
•
•
13-24
View THD -View the THD of the current FFT spectrum.
Gain -Changes the gain setting of the instrument.
Generally use 0dB gain for levels at 70dB SPL and
above, and 30dB gain for levels less than 70dB SPL. The
Auto Gain Control (AGC) function of the linearity
displays step between 0 and 30 dB gain, if the gain
setting is something other than 0 or 30 the AGC function
is inhibited.
Bandwidth -Setting to select the FFT bandwidth,
choices are include 200, 500, 1k, 2k, 5k, 10k and 20k
Hertz. The default is 10kHz. If the THD of signals with
fundamental frequencies above 2500Hz is to be measure,
choose a Bandwidth of 20kHz so that the 2nd through
4th harmonics are captured.
Window -Setting for the FFT window type. Choices are
Rectangular, Hanning and Flat-top. Hanning is required
for THD and frequency calculations.
824 Reference Manual
2/6/17
•
Weighting -Frequency weighting setting for the FFT.
This setting controls an analog filter prior to analog to
digital conversions whereas the RTA/SLM and Pulse/FM
mode use Flat analog weighed electronics and digital
filtering. The default value is A weighting so that the
Linearity FFT display has the greatest noise rejection.
The Flatness FFT display overrides this setting and
forces the electronics to be Flat weighted.
Note: The Linearity FFT display when using A or C
weighting should not be used to measure frequency response
and is not good to use for absolute amplitude measurement.
Always zero the display at your reference point and use the
relative level to see changes in amplitude relative to that
reference. Note also that the FFT's A and C weighting filters
may have up to ±0.2dB variation compared to the FFT Flat
weighting (due to component variations and tolerance).
To make absolute or flat weighted measurements, ensure
that the Weighting setting is set to Flat.
2/6/17
AUD (Optional)
13-25
13-26
824 Reference Manual
2/6/17
APPENDIX
A
Serial Port Interface Remote
Control
The System 824 is fully controllable remotely via the Serial
Port interface. Settings and the operational mode can be
changed by sending commands through the serial port. Data
can also be downloaded to and settings queried and set by
the controlling computer.
The System 824 may be connected to the computer directly
or through a modem. A network of many instruments can be
formed, all controlled by one computer by using the addressability mode.
This chapter will describe the Serial Port interfacing of the
System 824 and the various interface commands with their
syntax. Modem control is also covered.
Command text files and programming examples are
available
upon
request
via
email
to
techsupport@LarsonDavis.com.
Interface Cables
The communication parameters are
the following: The baud rate is
adjustable from 300 to 115200 baud,
8 data bits, parity is “None” and
stop bits are “1”. See section
“Communication” on page 3-33 for
a description of the communication
parameters)
2/6/17
Serial Port communications are made through the 8-pin
connector at the base of the Model 824. The instrument’s
signals conform to the RS-422 standard and are compatible
with RS-232C. The connectors use the same pin out and
cables as Apple® Macintosh® computers.
CBL006
824 to computer cable (9 pin female ‘D’)
CBL002
824 to serial printer (25-pin male ‘D’)
CBL003
824 to modem cable (25 pin male ‘D’)
CBL091
824 to HP LaserJet (9 pin male ‘D’)
A-1
Connection to a computer
using CBL006
Step 1
With the instrument turned off, insert the cable
connector in the instrument’s 8-pin port.
Step 2
Connect the CBL006 cable to the serial port of the
computer, using the supplied 9 to 25 pin adapter as
necessary.
Pin configurations for the CBL006
824 8-pin Connector End
HSO
HSI
Type
Computer 9-pin RS-232 Connector End
Type
Pin 1 Handshake Out
O
RS-232 DSR
CTS
Pin 6 DataSetReady
Pin 8 Clear to Sent
I
O
Pin 2 Handshake In
O
RS-232 DTR
Pin 4 Data Terminal Ready
O
TXD-
Pin 3 Transmitted Data (-)
O
RS-422 RD
Pin 2 Receive Data
I
GND
Pin 4 Ground
X
RS-422 GND
Pin 5 Ground
X
RXD-
Pin 5 Received Data (-)
I
RS-422 SD
Pin 3 Send Data
O
TXD+
Pin 6 Transmitted Data (+) O
RS-422
No Connection
CXI
Pin 7 Com. Extra Input
I
RS-232
No Connection
RXD+
Pin 8 Received Data (+)
I
RS-422 GND
Pin 5 Ground
Note that the pin configurations for the newer “thin”
CBL006 with the wrap-around label are slightly different as
shown below. Both versions work properly with the Model
824.
A-2
824 Reference Manual
2/6/17
‘Daisy Chain Addressing
The following instruments are
compatible on a common network:
Models 712, 720, 812, 814, 824, 870,
and TAC100. Future instruments
may also be compatible with this
network.
A network of instruments may be interconnected to one
computer using the appropriate cabling, and each may be
controlled individually. Each is given a unique address. By
default, all 824s are given an address based on their serial
number from 1 to 100. Serial numbers that end with two
zeros will be addressed as 100. The addresses are sent as a
single byte ranging in value from 129 to 228 representing
address 1 to 100 respectively (address plus 128), while
addresses 101 through 127 are reserved. At power-on all
824s are address enabled (as if they had just received their
address). Whenever an address byte is received, only the
corresponding instrument is enabled to receive and respond
to commands.
A broadcast command can be sent. By sending an address of
zero, CHR$(128), all units on the chain will become
addressed and accept the commands that follow. Only the
device with an address of 1 will respond to the commands.
This will allow all units to be started at the same moment, or
to have the same setting sent to all devices with one
command, i.e. set all clocks to the current time.
824 Network, Addressing Commands
NOTE: Hexadecimal notation: The dollar symbol “$” is used to indicate hexadecimal notation. Example: $1A is the
hexadecimal notation for the decimal
value of 26.
Command
0
2/6/17
The addressing of multiple 824s on a RS-422 network has
been enhanced so as to allow binary data blocks to be sent to
the 824 (and not be interpreted as an address), to
automatically identify all 824s on the network, and to
control the baud rate from the computer more easily. The
command details follow:
Description
Address 0 ($80), Broadcast, will enable addressing of all 824s on the net in a
broadcast receive mode. Only the 824 with address 1 will respond; all will
receive the command.
A -3
127
Address 127 ($FF), Address All, will enable all 824s to receive and respond to
commands; in other words it will disable the addressing feature of all 824s on
the net. Useful when only one device is connected.
126
Address 126 ($FE), Disable All, will disable all 824s and none will respond to
commands received. This is useful when trying to communicate with one device
on the net that has addressing disabled by having its address set to zero.
125
Address 125 ($FD), Lock, will lock the current addressing of all 824s on the net
so that binary setting data may be sent to the currently addressed 824. To cancel
the lock so that addressing may be changed a <break> is sent.
124
Address 124 ($FC), Auto ID, will initiate an Auto-Identification of all 824s on
the net using a timing scheme based on each unit's address. The data received
will be the address byte from every device on the net delayed by 10mS times the
address; thus it will take a maximum of 1 second to receive the byte from unit
100.
<break>
A short break will cancel the addressing lock initiated with the 125 address command, so that addressing may be changed.
<break>
<break>
Two breaks in a row will re-initialize the I/O and Printer tasks and the clear the
data and command buffers. It will also address all instruments (first command
should be an address).
<break>
<break>
<break>
Three breaks in a row will cause all 824s on the network to temporarily change
to 9600 baud to ensure that all devices on the net can be communicated with.
Note: The baud rate is not changed if in modem mode and connected. These
should be “Long” breaks (>50ms) to accommodate a unit set at 300 bps. Use the
S2283, n command to temporarily set the I/O baud rate where ‘n’ indicates the
new rate (see pg. B-30)
Commands
The commands are a series of ASCII characters with an
alpha command and one or two numeric operands followed
by a carriage return, ASCII 13. The commands may be
spelled out though only the first character is significant. i.e.
READ 123 may be abbreviated to R123. Every command
has a response to acknowledge that it was received correctly
and to provide data requested. For high reliability systems
A-4
824 Reference Manual
2/6/17
there is an error-checking protocol that will ensure proper
command data transferal. See “Error Checking Protocol”.
Commands will be discussed according to the following list:
Commands
Symbol
Mode Commands
M
Read Commands
R
Settings Commands
S
History Oriented Commands
E, I, D, L, C, H, T
Print Commands
P
Error Messages & Warnings Commands
Modem Control Commands
Miscellaneous Commands (unsupported)
Key Simulation Commands
K
Remote Control Commands (Detailed)
Mode Commands
Format for the Mode Commands is:
Command
Description
M1
Power On (clear error message list and reset display functions to “–a” windows)
M2
Power Off (cease sending further commands or the 824 will power back on)
M3
Run (begin accumulating data)
M4
Stop (stop accumulating data)
M4,1
Pause/Continue or View/End view (if stopped) (See R152 through R154)
2/6/17
A -5
M5
View (view the current Sound Pressure Level without accumulating data)
M6 or
M6,0
Set standard mark
M6,1
Set mark 1, Aircraft
M6,2
Set mark 2, Automobile
M6,3
Set mark 3, Truck
M6,4
Set mark 4, Train
M6,5
Set mark 5, Animal
M7 or
M7,0
Reset current data (instantly resets the current data set)
M7,1
Overall Reset (Resets the Current and Overall SLM function and histories [synonym
of S1,1 Reset-All command]
M7,2
Purge All (Resets ALL data and erases ALL data files [To purge, error checking
must be on; the check character for M7,2 is “b”; therefore, the complete purge command is M7,2b (case is significant!)]
M8
Reset Histories Only (clears all histories and places a RESET record in the run log)
M 9,1
Enable High Resolution Levels (nnn.nn for all sound level data (to I/O channel))
M 10
Lock 824 (leaves 824’s power on)
M 11
Lock 824 and Power Off (cease sending further commands)
M 12
Disconnect Modem (terminate connection and hang up)
M 13
Extend Modem Connect Time-out (can be set up to 255 seconds and allows time for
modem diagnostics)
M1000
Test RAM (non-destructive walking bit test; data left intact)
M1001
Test RAM (destructive pattern fill & test, setup recalled from EEPROM)
M2222
Store current setup to EEPROM (Response (“Stored!”) takes ~20 seconds)
@
Enable I/O Error Check Scheme (documentation available on request. S205,0F or 2
to 3 <CR> in a row will disable Error Checking)
A-6
824 Reference Manual
2/6/17
“Read” Commands (Reads out data variables)
The various read commands are detailed in the following
tables. The tables list the variable number, the variable
name, a description, data format, and instrument types for
which it is valid. Some of the Read commands also utilize a
second operand.
Syntax
Instrument
Type
Description
Response
R1
All
Device manf. and model (30 characters)
String
R1, 1
All
Option feature identification. (8 characters)
Used to determine optional features of the system. The
returned string will show the availability of a filter card,
the ENV firmware option and the memory options. The
filter has 3 options: None (F0), 1/1 octave filters (F1) and
1/1 plus 1/3 octave filters (F3). The Environmental noise
analyzer option is either present (E1) or not (E0).
The memory has 4 options.
Standard 1/2 megabyte (M0), 1 megabyte (M1), 1.5 megabyte (M2) and 2 megabyte (M3).
Example: “F3 E0 M3” means there is a 1/3 octave filter
installed, there is no ENV option, and the memory is the
standard 2 megabytes.
F3 E0 M3
R1,2
All
Read Model string “824”
824
R1,3
All
Read Flash Identification “hhhh” Manf/Device Code (IF
13)
IF 13
R1,4
All
hhhh (options installed in hex)
R1,5
All
Reads out the RTC’s (real-time clock) serial number in
hexadecimal
R1,128
All
Read ConfigFlag “hh” (in hex)
R1, n
All
Test selected bits in Configflag. (n=129-255)
Selected bits in ConfigFlag can be tested. If any of the
specified bits are set = 1, then the response will be “Yes”
2/6/17
A -7
otherwise the response is “No”. The following examples
show how bits in ConfigFlag can be tested. (The binary
number shown is the binary value of the decimal operand of
the R1 command.)
Command
Instrument
Type
Binary Value
ConfigFlag Bits
Tested
R1,129
All
10000001
0
R1,130
All
10000010
1
R1,132
All
10000100
2
R1,192
All
11000000
6
R1,170
All
10101010
1,3,5
NOTE: the 7th bit of ConfigFlag cannot be tested.
Syntax
Instrument
Type
Description
Response
R2
ALL
Current Date and Time
ddd ddmmmyyyy hh:mm:ss
R3
ALL
Status
Run mode, Lock, Logic In,
Alarm, Archive 0
R3,1
ALL
Short status string
cccccc
R3,2
ALL
Short status string and reset alarm
tripped status
cccccc
A short status string for R3,1 and R3,2 has a 6 character
response (cccccc).
•
•
•
A-8
The first character is an “s” when stabilizing or a space
when stable.
The second character is the current mode: “S” for
Stopped, “R” for Running, “P” for Paused, “C” for Calibrating, “V” for View mode, “O” for stopped with overall data reset and “C” for stopped with Current data set
reset.
The third character is the instrument Lock Status and is
either an “L” or a “U”.
824 Reference Manual
2/6/17
•
•
•
The fourth character is the Logic Input Status and is a
“1” if high and a “0” if low.
The fifth character will be an “a” if an Alarm has been
detected, otherwise it will be a space.
The sixth character is the modified status of the active
setup (ID), space for unmodified and “A” for archive.
R3,3
ALL
Status of Active ID
Archive Status, “A” indicates that it has
been modified since being uploaded.
Changed Status, “C” indicates that it has
been changed and not saved back to it’s
ID.
ID from file, “F” indicates that it has
been recalled from a data file.
ccc
R3,4
ALL
Active File Number
ccc
R3,5
ALL
Reads out the number of DEMOs used
xx
R4,x
ALL
Current SPL
nnn.nn dB
R5
ALL
OverAll Runtime
hhhhh:mm:ss.s
R6
ALL
OverAll Start Date and Time
ddmmmyy hh:mm:ss
R7
ALL
Current Runtime
hhhhh:mm:ss.s
R8
ALL
Current Start Date and Time
ddmmmyy hh:mm:ss
R9,w
LOG
Overall TWA (Time Wght Avg)
nnn.n dB
R10
SSA, ISM,
LOG
Overall Exchange Rate Text
ccccc
R11,w
SSA, ISM,
LOG
Current TWA (Time Wght Avg)
nnn.n dB
R 12
SSA, ISM,
LOG
Current Exchange Rate Text
ccccc
R13,w
LOG
Overall SEL
nnn.n dB
2/6/17
A -9
R14,w
SSA, ISM,
LOG
Current SEL
nnn.n dB
R15,x
LOG
OverAll Minimum Level
nnn.n dB
R16,x
LOG
OverAll Lmin Date and Time
ddmmmyy hh:mm:ss
R17,x
SSA, ISM,
LOG
Current Minimum Level
nnn.n dB
R18,x
SSA, ISM,
LOG
Current Lmin Date and Time
ddmmmyy hh:mm:ss
R19,x
LOG
OverAll Maximum Level
nnn.n dB
R20,x
LOG
OverAll Lmax Date and Time
ddmmmyy hh:mm:ss
R21,x
SSA, ISM,
LOG
Current Maximum Level
nnn.n dB
R22,x
SSA, ISM,
LOG
Current Lmax Date and Time
ddmmmyy hh:mm:ss
R23,w
LOG
OverAll Peak Level
nnn.n dB
R24,w
LOG
OverAll Lpeak Date and Time
ddmmmyy hh:mm:ss
R25,w
SSA, ISM,
LOG
Current Peak Level
nnn.n dB
R 26,w
SSA, ISM,
LOG
Current Lpeak Date and Time
ddmmmyy hh:mm:ss
R27,w
LOG
OverAll UWPk Level (Peak Level 1)
nnn.n dB
R28,w
LOG
OverAll Luwpk Date and Time
ddmmmyy hh:mm:ss
R29,w
SSA, ISM,
LOG
Current UWPk Level (Peak Level 1)
nnn.n dB
R30,w
SSA, ISM,
LOG
Current UWPk Date and Time
ddmmmyy hh:mm:ss
R31
LOG
OverAll RMS Exceedances #1
nnnnn
R32
LOG
OverAll RMS Exceedances #2
nnnnn
A-10
824 Reference Manual
2/6/17
R33
LOG
OverAll Peak Exceedances
nnnnn
R 34
LOG
OverAll UWPk Exceedances
nnnnn
R35
ALL
Overloads
nnnnn
R36
ALL
Number of PAUSES
nnnnn
R37
ALL
PAUSE Time (OFF Time not inc.)
hhhhh:mm:ss
R38
LOG, SSA
Ln 1
nnn.n dB
R39
LOG, SSA
Ln 2
nnn.n dB
R 40
LOG, SSA
Ln 3
nnn.n dB
R 41
LOG, SSA
Ln 4
nnn.n dB
R42
LOG, SSA
Ln 5
nnn.n dB
R43
LOG, SSA
Ln 6
nnn.n dB
R44
LOG
Overall Dose
nnnnn.n%
R45
SSA, ISM,
Current Dose
nnnnn.n%
R46
LOG
Overall Projected Dose
nnnnn.n%
R47
SSA, ISM,
LOG
Current Projected Dose
nnnnn.n%
R54
ALL
Last Level Relative to REFLVL
-nnn.n
R55
LOG
Display Histogram Selected
ccc
R 56
LOG
Display Total Counts in Ln Table
nnnnnk
R 57
LOG
Overall Leq
nnn.n dB
R 58
LOG
Daily Leq
nnn.n dB
R 59
LOG
Current Hourly Leq
nnn.n dB
R60,h
LOG
Hourly Leq (h= 0-23)
nnn.n dB
R61,h
LOG
Hourly Leq partial indicator(h=0-23)
nnn.n dB
R62
LOG
Overall LDN
nnn.n dB
2/6/17
A -11
R63
LOG
Daily LDN
nnn.n dB
R64
LOG
Hourly LDN
nnn.n dB
R65
LOG
Overall CNEL
nnn.n dB
R66
LOG
Daily CNEL
nnn.n dB
R67
LOG
Hourly CNEL
nnn.n dB
R68
LOG
Total EXCD Leq
nnn.n dB
R69
LOG
Total EXCD Time
hhhhh:mm:ss.s
NOTE: The exceedance Leq, R68, and
exceedance time, R69, include data from
qualified events that are stored in the
EXCD History. If an event is discarded
because it was shorter than the minimum
duration then it will not be included in
these values.
R70
LOG
Background Leq
nnn.n dB
R86
ALL
Battery Level
nnn%
R87
ALL
Battery Source (INT/EXT)
ccc
R88
ALL
Temperature
-nnn.n
R89
ALL
Serial Number
ccccc
R90
ALL
Firmware Rev. & Rev. Date
n.nnn ddmmmyyyy
R91
ALL
Free Memory
nnnnnnn
R92
LOG
Number of RUN/STOP Records
nnnnn
R93
LOG
Number of EXCD Records
nnnnn
R94
ALL
Number of INTV Records
nnnnn
R95
LOG
Number of HIST Records
nnnnnnn
R96
LOG
Number of Daily Records
nnnnn
R97
LOG
Number of Cal Records
nnnnn
A-12
824 Reference Manual
2/6/17
R98,n
ALL
Error Message List (n= 1 to 8)
cccccccccccccccccccccc
n = 1 to the last error. If
n=0 or omitted then the 8
error codes are output as
number. (nnn, nnn, . . .
nnn).
R99
ALL
Logic Output 1 State
[On/Off}
R100
ALL
Logic Output 2 State
[On/Off}
R101
ALL
Report Number
nnnnn
R102
ALL
Page Number
nnnnn
R103
ALL
Printer Line Number
nnn
R104
ALL
Calibration Date/Time
ddmmmyy hh:mm:ss
R105
ALL
Cal Check Date/Time
ddmmmyy hh:mm:ss
R106
ALL
Cal Offset
nnn.n
R107
ALL
Cal check Level
nnn.n + OFFSET
R108
SSA, ISM, LOG
RMS Exceedance Flag 1
*
R109
SSA, ISM, LOG
RMS Exceedance Flag 2
*
R110
SSA, ISM, LOG
PEAK Exceedance Flag
*
R111
SSA, ISM, LOG
UWPK Exceedance Flag
*
R112
ALL
System Overload Flag
*
R113
LOG
Excd Exchange Rate Text
ccccc
R114
LOG
Intv Exchange Rate Text
ccccc
R115
ALL
Auto-Advance History Indicator
+
R116
ALL
Current Wind Speed, Frequency or
Tach
nnn.n or nnnnn
R132
LOG
Today’s Minimum Level
nnn.n dB
R 133
LOG
Today’s Maximum Level
nnn.n dB
2/6/17
A -13
R 134
LOG
Today’s Peak Level
nnn.n dB
R135
LOG
Today’s UWPk Level
nnn.n dB
R136
LOG
Today’s Runtime
hh:mm:ss | mm:ss.ss
R137
SSA, LOG
Next Alarm Time
hh:mm
R138
SSA, LOG
Interval Date and Time of Occurrence
ddmmmyy hh:mm:ss
R139
SSA, LOG
Interval Duration
hh:mm:ss / mm:ss.ss
R140
SSA, LOG
Interval Lint
nnn.n dB
R141
SSA, LOG
Interval SEL
nnn.n dB
R142
SSA, LOG
Interval Lmin
nnn.n dB
R143
SSA, LOG
Interval Lmax
nnn.n dB
R144
SSA, LOG
Interval Lpeak
nnn.n dB
R145
SSA, LOG
Interval UnWeighted Peak
nnn.n dB
R146
SSA, LOG
AUTO-SEND HISTORY LEQ
nnn.n dB
R150
ALL
Number of RUNS & CONTINUES
nnnnn
R151
ALL
Power On Fault Cause Character
c
D - Data Checksum Corrupt
E - EEPROM Checksum Corrupt
K - Key Reset (R+ l+ v)
P - setting Checksum Corrupt
O - Opcode Error
R - RAM Setup Register Corrupt
T - Test Memory Corrupt
W - Watchdog Reset
An indicator has been added to the ON display on the top
line of the 824’s display to show faults that were detected by
A-14
824 Reference Manual
2/6/17
the power on test procedure. The R151 command will
display the fault character to a computer.
R152
ALL
Internal RMS detector level
nnn.nn dB
R153
ALL
Internal PEAK detector level
nnn.nn dB
R154
ALL
Internal UwPk detector level
nnn.nn dB
R155
ALL
Number of Bytes in Keyboard Stack
This is used with keyboard simulation
to prevent the loss of keys.
nnn
R156
LOG
Background Leq Time
hhhhh:mm:ss.ss
R157
ALL
Calibration Status
Done, Wait, Waiting, Stable,
Unstable, Too High, Too
Low.
R158
ALL
Total Memory Available
nnnnnn
R159
ALL
Memory Available in percent
nnn.nn
R160
ALL
OVERALL OVERLOAD FLAG
c
R161
RTA
Number of RTA Records
nnnnn
R162
LOG
Overall Sound Exposure
nnnnn.n P2H
Sound Exposure (E) is calculated and displayed in pascal
squared hours as needed in some of the European Countries.
2/6/17
A -15
This value is read with the R162 command and is available
in the top line of the DOSE-a display. The formula used is:
E = T • (10^(Leq/10)) • 20µPa2,
where E is the Exposure, T is the elapsed time in hours, and
20µPa2 is the reference sound pressure 20 micro pascal
squared.
R163,x
SSA, ISM,
LOG
TAKT 3
nnn.n dB
R164,x
SSA, ISM,
LOG
TAKT 5
nnn.n dB
R165
LOG
PassBy Time of Occurrence
ddmmmyy hh:mm:ss
R166
LOG
PassBy Event Duration
hh:mm:ss / mm:ss.ss
R167
LOG
PassBy Lmax
nnn.n
R168
LOG
PassBy Leq
nnn.n
R169
LOG
PassBy SEL
nnn.n
R170
ALL
External Battery Level in Volts
nn.n V
R171,f
SSA, AUD,
TAL
RTA filter - LIVE Level
*f is ANSI filter
nnn.n dB
R172,f
SSA, TAL
RTA filter - CURRENT Leq
*f is ANSI filter
nnn.n dB
R173,f
SSA, TAL
RTA filter - OVERALL Leq
*f is ANSI filter
nnn.n dB
R174,f
SSA, LOG,
RTA, AUD,
TAL
RTA filter selected frequency
*f is ANSI filter
cccccHz
R175
ALL
OverAll End Date and Time
ddmmmyy hh:mm:ss
R176
ALL
Current End Date and Time
ddmmmyy hh:mm:ss
R177
ALL
OverAll Reset/Began Text
“Reset” or “Began”
A-16
824 Reference Manual
2/6/17
R178
ALL
Current Reset/Began Text
“Reset” or “Began”
R179
ALL
Total bytes of RAM installed in the
SLM
nnnnnnn
R180
ALL
Current Instrument Type
ccc
R181
ALL
Number of Data File Records
nnn
R182
ALL
Data File History Record Size
nnnnnnn
R187
ALL
SLM Firmware Rev. Number &
Revision Date
n.nnn ddmmmyyyy
R188
SSA
RTA Spectra at Lmax
nnn.n dB
R189
ALL
Logic Input State
‘On’ or ‘off’
R190
ALL
Noise Floor Indicators
c or cccc, flags
R191
AUD
Audiometric Test, Rise Time
nnnnn.nn
R192
AUD
Audiometric Test, Fall Time
nnnnn.nn
R193
AUD
Audiometric Test, On Time
nnnnn.nn
R194
AUD
Audiometric Test, Off Time
nnnnn.nn
R195
AUD
Audiometric Test, Plateau Time
nnnnn.nn
R196
AUD
Audiometric Test, Overshoot Level
nnn.n
R197
AUD
Audiometric Test, Level
nnn.n
R198
AUD
Audiometric Test, FFT Frequency
nnnnn.nn
R199
AUD
Audiometric Test, Carrier Frequency
nnnnn.nn
R200
AUD
Audiometric Test, Max Frequency
nnnnn.nn
R201
AUD
Audiometric Test, Min Frequency
nnnnn.nn
R202
AUD
Audiometric Test, Modulation Frequency
nnnnn.nn
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R203,l
AUD
FFT Live Spectrum Level (,
line_number) l=line#, 0 - 400
nnn.nn
R204,l
AUD
FFT Live Spectrum Frequency
(,line_number) l=line#, 0 - 400
nnnnn
R205
FFT, AUD
FFT Live Broadband Level
nnn.n
R206,f
SSA
RTA Minimum Level per Spectrum
Filter
nnn.n
R207,f
RTA
Live Spectrum (f=ANSI filter number or -1 for Flat)
nnn.n
R208
RTA
Live Spectrum’s Duration
s.ssss
R209
RTA
Live Spectrum’s Overload Status
‘Ovld’
R210,f
RTA
Leq Spectrum (f=ANSI filter number or -1 for Flat)
nnn.n
R211
RTA
Leq Spectrum’s Duration
hhhhh:mm | hh:mm:ss |
mm:ss.ss | ss.ssss
R212
RTA
Leq Spectrum’s Overload Status
‘Ovld”
R213,f
RTA
Lmax Spectrum ,n (n=ANSI filter
number or -1 for Flat)
nnn.n
R214,f
RTA
Lmin Spectrum (f=ANSI filter number or -1 for Flat)
nnn.n
R215
RTA
Trigger State
‘Stop, Ready, Armed, Trigd,
Ended’
R216
RTA
Pre-Trigger Samples
nnn
R217
RTA
Triggered ByTime Samples
R218, n
RTA
Triggering String (,n) 1&2=ARM,
3&4=Trig, 5&6=End, 7=Repeat 21
character string, 0=all strings
character string
R219,f
RTA
Spatial Averaged Spectrum
(f=ANSI filter number or -1 for
Flat)
nnn.n
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R220
RTA
Spatial Averaged sample count
nnnnnk
R221,f
RTA
Room Spectrum (f=ANSI filter
number or -1 for Flat)
nnn.n
R222,f
RTA
Room Class Spectrum (f=ANSI filter number or -1 for Flat)
nnn.n
R223
RTA
Room Level, SIL or Lmf in dB
nnn.n
R224
RTA
Room Data, NCB or RC
nn
R225
RTA
Room Flags: Over/Under/Hiss/
Rumble/Vibra
ccccc
R226,n
ALL
Display the Last history record type
0 - Last record type string
1 - Date/Time of last record
2 - Duration/Runtime of last rec.
3 - Record Size (bytes)
4 - Instrument type of record
ccccccccc
ddmmmyyyy, hh:mm:ss
hhhhh:mm, hh:mm:ss, mm:ss.ss
nnnnnnn
ccc
R227
TAL
Tonal Frequency in Hz
nnnnn
R228
TAL
Tonal delta Frequency in Hz
nnnnn
R229
TAL
Tonal Level
nnn.n
R230
TAL
Tonal Group Level
nnn.n
R231
TAL
Tonal Background Level
nnn.n
R232
TAL
A weight Impulse Leq, Overall
nnn.n
R233
TAL
Tonality Run Time
hh:mm:ss
R233
LOG
Excd Duration
mm:ss.ss
R234,f
SSA
Ln 1 Spectrum, dB (f=ANSI filter
number)*
nnn.n
R235,f
SSA
Ln 2 Spectrum, dB (f=ANSI filter
number)*
nnn.n
R236,f
SSA
Ln 3 Spectrum, dB (f=ANSI filter
number)*
nnn.n
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R237,f
SSA
Ln 4 Spectrum, dB (f=ANSI filter
number)*
nnn.n
R238,f
SSA
Ln 5 Spectrum, dB (f=ANSI filter
number)*
nnn.n
R239,f
SSA
Ln 6 Spectrum, dB (f=ANSI filter
number)*
nnn.n
R240,n
SSA
Ln percentage stored with the spectra (n=the percentage number from
1 to 6)**
nn.nn
R241,n
AUD, FFT
Total harmonic distortion & frequency
see following commands
R241,
512
AUD, FFT
Extract harmonic distortion data
from FFT Live
no output data
R241,
1024
AUD, FFT
Extract harmonic distortion data
from FFT Snapshot
no output data
R241,0
AUD, FFT
Show precise frequency of fundamental
nnnnnn Hz
R241,
256
AUD, FFT
Show level of fundamental
nnn.n dB
R241,n
AUD, FFT
Show distortion of harmonic ‘n’,
n=1 to 20
n.nn %
R241,
n+256
AUD, FFT
Show harmonic levels minus fundamental level ‘n’, n=1 to 20
-nnn.n dB
R241,
n+512
AUD, FFT
Show distortion of harmonic levels
‘n’ and above
n.nn %
R241,
n+768
AUD, FFT
Show distortion of harmonic ‘n’,
and above minus fundamental level,
n=1 to 20
-nnn.n dB
R241,
n+1024
AUD, FFT
Show noise floor influence indicator
for harmonic ‘n’, n=1 to 20 (valleys
have less than 10 dB from harmonic)
“ “ if no influence
“*” if influence detected
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824 Reference Manual
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R242
ISM, LOG,
SSA, AUD,
TAL
Live Leq detector sample
(Weight setting applies)
nnn.n dB
R243
ISM, LOG,
SSA, AUD,
TAL
Live Lmax detector sample
(Weight and Detector settings apply)
nnn.n dB
*If f=0 then all 33 filter levels will be output in a comma
delimited string.
**If n=0 then all 6 percentages will be output in a comma
“ANY DATA” READ COMMANDS
The 824 measures SPL data with three frequency weightings
and with three time weighting detectors simultaneously, as
well as peak and integrated levels with three frequency
weightings. To access this additional data use these Read
Commands using the second operand indicated:
{SSA, ISM, LOG and ENV instruments only}
R 4,x
SSA, ISM, LOG
Current SPL
(Any Wght/
Dect)
nnn.n dB
R 9,w
SSA, ISM, LOG
OVERALL TWA
(Any Wght)
nnn.n dB
R 11,w
SSA, ISM, LOG
CURRENT TWA
(Any Wght)
nnn.n dB
R 13,w
SSA, ISM, LOG
OVERALL SEL
(Any Wght)
nnn.n dB
R 14,w
SSA, ISM, LOG
CURRENT SEL
(Any Wght)
nnn.n dB
R 15,x
SSA, ISM, LOG
OverAll Minimum
Level
(Any Wght/
Dect)
nnn.n dB
R 16,x
SSA, ISM, LOG
OverAll Lmin Date
and Time
(Any Wght/
Dect)
ddmmmyy hh:mm:ss
R 17,x
SSA, ISM, LOG
Current Minimum
Level
(Any Wght/
Dect)
nnn.n dB
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R 18,x
SSA, ISM, LOG
Current Lmin Date
and Time
(Any Wght/
Dect)
ddmmmyy hh:mm:ss
R 19,x
SSA, ISM, LOG
OverAll Maximum
Level
(Any Wght/
Dect)
nnn.n dB
R 20,x
SSA, ISM, LOG
OverAll Lmax Date
and Time
(Any Wght/
Dect)
ddmmmyy hh:mm:ss
R 21,x
SSA, ISM, LOG
Current Maximum
Level
(Any Wght/
Dect)
nnn.n dB
R 22,x
SSA, ISM, LOG
Current Lmax Date
and Time
(Any Wght/
Dect)
ddmmmyy hh:mm:ss
R 23,w
SSA, ISM, LOG
OverAll Pk Level
(Any Wght)
nnn.n dB
R 24,w
SSA, ISM, LOG
OverAll Lpk Date
and Time
(Any Wght)
ddmmmyy hh:mm:ss
R 25,w
SSA, ISM, LOG
Current Pk Level
(Any Wght)
nnn.n dB
R 26,w
SSA, ISM, LOG
Current Lpk Date
and Time
(Any Wght)
ddmmmyy hh:mm:ss
R163,x
SSA, ISM, LOG
TAKT 3
(Any Wght/
Dect)
nnn.n dB
R164,x
SSA, ISM, LOG
TAKT5
(Any Wght/
Dect)
nnn.n dB
Where “x” indicates a number to represent a combination of
weighting and detector which has these values:
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1
A weight, Slow detector
2
A weight, Fast detector
3
A weight, Impl detector
4
C weight, Slow detector
5
C weight, Fast detector
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6
C weight, Impl detector
7
Flat weight, Slow detector
8
Flat weight, Fast detector
9
Flat weight, Impl detector
If “x” is not provided or it is zero then the value indicated by
the Wght and Detc settings is given.
NOTE: Impulse detector is not applicable for Takt levels
Where “w” indicates a number to represent the weighting
which has these values (Detector is not applicable for these
measurements):
1
A weight
2
C weight
3
Flat weight
If “w” is not provided or it is zero then the value indicated
by the Wght settings is given.
Other Read Commands
Other read commands are macro commands that send
multiple “R” variables, so multiple data can be retrieved
from the 824 with one command. Other commands O 1, O 2,
and O 4 are preprogrammed macros while O 3 is a userdefined macro which is programmed by the Group
command.
Code
Description
Response
O1
Read SLM data
nnn.n, nnn.n, nnn.n, nnn.n<CR><LF> R 4 (SPL), R 11
(TWA), R 17, (Lmin), R 21 (Lmax)<CR><LF>)
O2
Read Wind Data
nnn.n, ccc, nnn.n, nnn.n, ccc<CR><LF>
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Code
Description
Response
O3
Read Group of “R” variables programmed by the
group programming command G n,r
<as programmed>
O4
Read 824’s LCD Display,
bit mapped in a binary format
<SOH><HIGH_COUNT><LOW_COUNT><...data...><C
HKSM><CR><LF>
• There are 1024 bytes of screen data (8 lines of 128 bytes
each)
• Bits in each byte represent a vertical column of 8 pixels
with the lsb on top
O6
All History Records: R92
(Run Log), R93 (Excd),
R94 (Intv), R95 (Time
History), R96 (Daily), R97
(Cal. Log)
nnnnnn,nnnnnn,nnnnnn,nnnnnn,nnnnnn,nnnnnn
O8
AUD, FFT
Read THD data: Fund. Frequency, Fund Level, THD+n,
2nd, 3rd, 4th, 5th and above.
nnnnnn, nnn.n, n.nn,n.nn,n.nn,n.nn
O9
AUD, FFT
Read Fund. Frequency and Fund. Level
nnnnnn, nnn.n
Group Read Programming
The group command permits the programming of a userdefined macro with up to eight (8) Read variables. The
macro is executed with the G0 or O[ther] 3 commands
which returns the list of defined read variables.
Use the following command syntax to program each desired
read variable and its position in the macro.
Syntax
Response
G[roup]n, var_no
<cr><lf>
Example: G1, 4 <cr>
assigns the current SPL to the first group option
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824 Reference Manual
2/6/17
Example: G2, 15 <cr>
assigns Lmin to the second option
Example: G3, 19 <cr>
assigns Lmax to the third option
Example: G4, 0 <cr>
terminates group command programming
Where n is from 1 to 8, indicating the macro position and
var_no is the number of the “R” variable associated with the
position. Use a var_no of “0” to define the last position
when less than eight are desired.
After programming this group read list, the response to G0 is
59.5, 38.6, 102.2; the SPL, Lmin and Lmax.
Setting Commands
The Settings select what functions are enabled and
determine how the measurements are performed. Settings
can be both set (S) and queried (Q). The setting numbers
provided below in the “Setting List” section are for both the
Set (S) and Query (Q) commands.
•
•
•
•
Option e.g. [Sun|Mon|Tues…|Sat]
Numeric e.g. (123.45)
Character e.g. (Gas Flare, Test 1); can be up to 30 characters
Template e.g. (hh:mm:ss)
Brackets [ ] indicate optional characters or operands.
<cr> = carriage return; <lf> = line feed; _ = space
Querying Settings
The current setting is retrieved with the Query (Q)
command. The syntax for the query command is
Q[uery ]setting_number[,options] where setting_number is
2/6/17
A -25
the number of the desired setting and options is a number to
select the appearance of the response.
Brackets [ ] indicate optional characters or operands. <cr> =
carriage return; <lf> = line feed; _ = space
Syntax
Response
Q[uery]item_number[,flag]
Depends on flag
Option flags elicit the following responses:
Flag
Response
none
Current setting
1
Setting name and current setting
2
Current setting (including spaces) in brackets or parentheses
3
Setting name and current setting (including spaces) in brackets or parentheses
32
Option number for option setting
Flag values may be added together for desired combinations:
Example:
Response
1.Q74
No
2.Q74, 1
Excd History Enable=No
3.Q74, 2
[_No]
4.Q74, 32
0
5.Q74, 3
Excd History Enable=[_No]
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Responses are denoted by (x) if Yes/No or (n) if numerical.
Ln Query Commands (SSA)
Commands
Instrument Type
Description
Comments
Q 63
SSA
Ln 1 Percent
nn.nn
Q 64
SSA
Ln 2 Percent
nn.nn
Q 65
SSA
Ln 3 Percent
nn.nn
Q 66
SSA
Ln 4 Percent
nn.nn
Q 67
SSA
Ln 5 Percent
nn.nn
Q 68
SSA
Ln 6 Percent
nn.nn
Q 139
SSA
Enable Lns
[No/Yes]
Q 224
SSA
Start Level
nn
Entering Settings
Option Settings
2/6/17
Settings are entered with the Set command. The syntax for
the Set command is S[ET ]setting_number, setting_value or
S[ET ]setting_number;option_text where setting_number is
the setting number, setting_value is the desired setting, and
A -27
option_text is the textual setting for the option settings
(those that have one setting from a list of possible settings).
Option settings can be set in two ways: a. option number and
b. actual option settings text.
a.Option Number
Syntax
Response
S[et]item_number,option_number
<cr><lf>
Example: S9, 3
sets setting 9:Baud Rate to option 3 which
sets the baud rate to 9600
Example: S674, 1
sets Excd History Enable to Yes.
Example: S95, 0
sets Hist Period Units to _1/32s
Example: S95, 1
sets Hist Period Units to _1.0s
b.Option Setting Text
Querying an option with a flag of 2
will return the setting’s value
enclosed in brackets as needed when
using the option text syntax.
Option settings texts is preceded by a semicolon and
enclosed by brackets. Option settings text must include the
same number of characters that are given when queried,
including spaces, which are indicated below with “__”.
Syntax
Response
S[et]item_number; [option_text]
<cr><lf>
Example: S9; [_9600]
sets Baud Rate to 9600.
Example: S74; [Yes]
sets Excd History Enable to Yes.
Example: S95; [_1/32s]
sets Hist Period Units to 1/32s
Example: S95; [_1.0s]
sets Hist Period Units to 1.0s
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824 Reference Manual
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Numeric Settings
Syntax
Response
S[et]item_number, setting_value
<cr><lf>
Example: S62, 120
sets RMS Excd Level 2 to 120.
Character String Settings
To include leading spaces in a character string setting,
precede the character string with a “`” (leading single quote
or grave accent, ASCII 96 or hexadecimal 60).
Syntax
Response
S[et]item_number, character_string
<cr><lf>
Example: S2; `
sets Name to ABC Acoustics.
ABC Acoustics
Template Settings
For example, when entering a date, the month, day, and year
are entered in that order; two numeric digits each and are
separated by “/”. The display shows date, month
(abbreviated), and year in that order normally, or in year,
month and date for ISO-8601 format (ddmmmyyyy or
yyyymmmdd).
Syntax
Response
S[et]item_number; mm/dd/yy
<cr><lf>
S28, 05/23/89
sets Timer Run Date to 23May1989.
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Times are entered in hour, minutes, and seconds order and
are separated by “:”. (24 hour clock time is used: i.e. hours 0
to 23.
Syntax
Response
S[et]item_number; hh:mm:ss
<cr><lf>
Example: S30, 09:25:00
Example: S6, 23:05:33
sets Timer Run Time 1 to 09:25:00.
sets current time to 23:05:33 (11:05:33pm)
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824 Reference Manual
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Setting List
Command
Instrument
Type
Description
S1,x
ALL
RESET-ALL
S2,c
ALL
HEADING LINE #1
S3,c
ALL
HEADING LINE #2
S4,c
ALL
HEADING LINE #3
S5,c
ALL
MEASUREMENT TITLE
S6,t
ALL
CURRENT TIME
S7,t
ALL
CURRENT DATE
S8,x
ALL
DAY OF WEEK
S9,x
ALL
Serial Communications Baud Rate
S10,n
ALL
Serial Communications Address
S11,x
ALL
Serial Communications Output Flow
Control
S12,x
ALL
Printer Serial Bit Rate
S13,x
ALL
Printer Serial Output Flow Control
S14,x
ALL
Logic-Output, Activation Mode
S15,n
ALL
Logic-Output Line Timer
S16,x
ALL
Logic-Output Line #2, Activation
Mode {Heater control line}
S17,n
ALL
Logic-Output Line #2 Timer
S18,x
ALL
LOGIC-IN LINE MODE
Comment
[None | Pause | Toggle | Level | Alarm]
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Where c = character, t = template, n = numeric, and x =
option index.
S19
ALL
External Power Type [AC Pwr|Battery]
S20
ALL
External Power-Off Voltage
S21
ALL
POWER SAVE OPTIONS [Blank
LCD / Auto Off / Manual Off]
S22
ALL
Standby Time (LCD Blank & Comm
Off) (nn)
0 to 99 minutes
S23
ALL
Auto-Off Time (nn)
0 to 99 minutes
S24
ALL
Backlight Power Off Time (nn)
0 to 99 seconds
S25
ALL
Backlight On/Off
S26
ALL
LCD Contrast 0 to 99% (nn)
S27
SSA, LOG
TIMER MODE
S28
SSA, LOG
TIMER RUN DATE
S29
SSA, LOG
TIMER STOP DATE
S30
SSA, LOG
TIMER RUN TIME1
S31
SSA, LOG
TIMER STOP TIME 1
S32
SSA, LOG
TIMER RUN TIME 2
S33
SSA, LOG
TIMER STOP TIME 2
S34
ALL
LOCK COMBINATION
S35
ALL
LOCK R/S KEY
S36
ALL
LOCK SETUP
S37
ALL
LOCK FUNCTION
S38
ALL
LOCK RESET
S39
ALL
LOCK THE ‘ON’ KEY
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824 Reference Manual
Protects External Battery
2/6/17
S40
ALL
LOCK I/O
S41
ALL
CAL LEVEL
S42
ALL
CALIBRATOR S/N
S43
LOG
AUTO-CALIBRATION MODE
S44
LOG
AUTO CAL TIME
S45
SSA, ISM,
LOG, AUD
DETECTOR
S46
SSA, ISM,
LOG, AUD
FREQUENCY WEIGHTING
S48
ALL
AC/DC Output Control [AC-1 AC-2 |
AC-1 DC | AC-2 DC | AC-2 AC-1]
S49
SSA, ISM,
LOG, AUD
Pk Detector Weighting [A | C | Flat]
S50
SSA, ISM,
LOG
RANGE [Normal | Low | High]
S51
ALL
Transducer Type [Air Condenser| Electret | Direct}
S52
SSA, ISM,
LOG, AUD
Simple SLM Displayed Value
S53
SSA, ISM,
LOG
CURRENT EXCHANGE RATE
S53
RTA
RTAf FILTER BANDWIDTH
S54
SSA, ISM,
LOG
CURRENT THRESHOLD
S54
RTA
RTAf DETECTOR
S55
LOG
CURRENT CRITERION
S55
RTA
LINEAR DETECTOR TIME
S56
LOG
OVERALL EXCHANGE RATE
2/6/17
[1/1, 1/3] OCTAVE
[LIN, EXP] TIME
WEIGHTING
SS.SSS SECONDS
A -33
S56
RTA
RTAf EXPONENTIAL DETECTOR
TIME
S57
LOG
OVERALL THRESHOLD
S57
RTA
RTAf EXPONENTIAL DETECTOR
STORAGE RATE
S58
LOG
OVERALL CRITERION
S58
RTA
RTAf RTAf AUTOMATIC RESET AT
TRIGGER
S59
LOG
CRITERION TIME (HOURS)
S59
RTA
RTAf AUTOMATICALLY STORE
EVENT RECORDS
S60
LOG
LDL EXCHANGE RATE
S60
RTA
RTAf ENABLE EVENT BYTIME
HISTORY
S61
LOG
LDL THRESHOLD
S61
RTA
RTAf EVENT BYTIME PRETRIGGER SAMPLES
S62
LOG
LDL CRITERION
S62
RTA
RTAf EVENT TRIGGERING
ENABLE
S63
LOG
Lnn 1 PERCENT
S63
RTA
RTAf TRIGGER SOURCE LEVEL
S64
LOG
Lnn 2 PERCENT
S64
RTA
RTAf ARM MODE
S65
LOG
Lnn 3 PERCENT
S65
RTA
RTAf ARM LEVEL
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824 Reference Manual
[1/64, 1/32, 1/16, 1/8, 1/4,
1/2, 1, 2, 4, 8, 16, 32, 64]
SECONDS
[1/2, 1/8] SECONDS
[NO, YES]
[YES, NO]
[NO, YES]
(NNN)
[NO, YES]
[12.5, 16.0 . . . 16.0K,
20.0K, FLAT] Hz.
[NOW, L<, L=, L>, INPUT,
TIME, COUNT]
(NNN.N) dB
2/6/17
S66
LOG
Lnn 4 PERCENT
S66
RTA
RTAf ARM TIME
S67
LOG
Lnn 5 PERCENT
S67
RTA
RTAf ARM SAMPLES
S68
LOG
Lnn 6 PERCENT
S68
RTA
RTAf ARM LOGIC INPUT TRUE
LEVEL
S69
SSA, ISM,
LOG
SPL Exceedance Level 1
S69
RTA
RTAf TRIGGER MODE
S70
SSA, ISM,
LOG
SPL Exceedance Level 2
S70
RTA
RTAf TRIGGER LEVEL
S71
SSA, ISM,
LOG
Peak-II Exceedance Level
S71
RTA
RTAf TRIGGER TIME
S72
SSA, ISM,
LOG
Peak-I Exceedance Level
S72
RTA
RTAf TRIGGER SAMPLES
S73
SSA, ISM,
LOG
EXCD HYSTERESIS
S73
RTA
RTAf TRIGGER LOGIC INPUT
TRUE LEVEL
S74
LOG
ENABLE EXCD HISTORY
S74
RTA
RTAF RUN MODE LOGIC INPUT
TRUE LEVEL
2/6/17
(SS.SSSS) SECONDS
(FOR LEVEL AND TIME
ARM MODE CONDITIONS)
(NNNN)
[LOW, HIGH]
[NOW, L<, L=, L>, INPUT,
TIME, COUNT]
(NNN.N) dB
(SS.SSSS) SECONDS
(NNNN)
[LOW, HIGH]
[LOW, HIGH]
A -35
S75
LOG
EXCD EXCHANGE RATE
S75
RTA
RTAf LOGIC OUTPUTS CONTROL
SETTING
S76
LOG
EXCD MINIMUM DURATION
S76
RTA
RTAf END MODE
S77
LOG
EXCD TIME-HIST ENABLE
S77
RTA
RTAf END LEVEL
S78
LOG
EXCD TIME-HIST PERIOD
S78
RTA
RTAf END TIME
(SS.SSSS) SECONDS
S79
RTA
RTAf END SAMPLES
(NNNNN)
S80
LOG
EXCD Passby Trigger Mode
S80
RTA
RTAf END LOGIC INPUT TRUE
LEVEL
S81
LOG
EXCD Occurrence Time [Start | Max]
S81
RTA
RTAf END THEN, REPEAT MODE
[STOP, REPEAT, AVERAGE]
S82
LOG
TIMED EXCD PERIOD
MM:SS
S82
RTA
RTAf REPEAT COUNT
(NNN) O TO 255 TIMES
S83
SSA, LOG
ENABLE INTV HISTORY
S83
RTA
RTAf AVERAGE COUNT
S84
SSA, LOG
INTV EXCHANGE RATE
S84
RTA
RTAf ANNUNCIATOR
S85
SSA, LOG
INTV THRESHOLD
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824 Reference Manual
(BIT MAPPED WORD: 3
OUTPUTS BY 5 STATES)
[NEVER, L<, L=, L>,
INPUT, TIME, COUNT]
(NNN.N) dB
[LOW, HIGH]
(N) 0 TO 9 TIMES
(CCCCCCCC) IF RIGHT
DIGIT IS NUMERIC IT
WILL AUTO-INCREMENT
2/6/17
S85
RTA
RTAf RT-60 CALCULATION dB
DOWN SETTING
S86
SSA, LOG
INTV PERIOD
S86
RTA
HORIZONTAL GRAPH SCALING
S87
SSA, LOG
INTV TIME SYNC
S88
LOG
INTV SAVE Ln’S
S90
SSA, LOG
INTV AUTO STOP
S91
LOG
ENABLE TIME HIST
S92
LOG
TIME HISTORY RESOLUTION
S93
LOG
Other TIME HISTORY Level
S94
LOG
TIME HISTORY PERIOD
S95
LOG
TIME HISTORY PERIOD UNITS
S96
LOG
HIST BASE
S97
LOG
HIST BASE MODE
S98
LOG
HISTOGRAM TABLE RESOLUTION
S99
LOG
ENABLE DAILY LDN HISTORY
S100
LOG
SAVE 6 DAILY Ln VALUES
S101
ALL
DATA REPORT
S102
SSA, LOG
R/S AND CAL LOG
S103
ALL
SETUP REPORT
2/6/17
[5, 10, 20, 30]
[1, 2, 3, 4, 6, 8, 11, 16, 23,
32, 45, 64, 90, 128, 181,
256, 362, 512, 724, 1024]
A -37
Histogram Reports
The RMS, Peak and UWPk histogram reports have been
implemented with this revision. The unformatted reports
have also been developed and the format is the level of the
first bin followed by the number of samples in each bin (in
hex, 0-9 & a–F). There are 1024 RMS bins and 128 Peak
and UWPk bins, this corresponds to 1/8th dB resolution for
RMS and 1dB resolution for the peak tables.
S104
LOG
SPL HISTOGRAM TABLE
(x)
S105
LOG
SPL HISTOGRAM TABLE LOW
VALUE
(n)
S106
LOG
SPL HISTOGRAM TABLE HI
VALUE
(n)
S107
LOG
SPL HISTOGRAM TABLE RESOLUTION
(x)
S108
LOG
PEAK-II HISTOGRAM TABLE
(x)
S109
LOG
PEAK-II HISTOGRAM TABLE
LOW VALUE
(n)
S110
LOG
PEAK-II HISTOGRAM TABLE HI
VALUE
(n)
S111
LOG
PEAK-II HISTOGRAM TABLE
RESOL
(x)
S112
LOG
PEAK-I HISTOGRAM TABLE
(x)
S113
LOG
PEAK-I HISTOGRAM TABLE LOW
VALUE
(n)
S114
LOG
PEAK-I HISTOGRAM TABLE HI
VALUE
(n)
S115
LOG
PEAK-I HISTOGRAM TABLE
RESOL
(x)
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824 Reference Manual
2/6/17
Tailored Report
S116
RTA
EXCD REPORT
S117
SSA, ISM,
LOG
INTV REPORT
S118
LOG
HIST REPORT
S119
LOG
DAILY NOISE REPORT
S120-142 Reserved settings
Miscellaneous
S143
AUD
Audiometric Calibrator Mode [SLM/
RTA | FFT | Pulse/FM]
S144
FFT
FFT Lines [100 | 200 | 400]
S145
AUD, FFT
FFT Bandwidth [200 to 20KHz]
S146
FFT
FFT Averaging Count (1 to 65535)
S147
AUD, FFT
FFT Window Type [Rectangular |
Hanning]
S148
SSA, RTA,
FFT, AUD,
INT
RTA Gain (Range control for SLM/
RTA instruments) [-20 | -10 | +0 | +10 |
+20 | +30 | +40 | +50]
S149
SSA, AUD
RTA Detector Rate [Slow | Fast]
S150
SSA, ISM,
AUD
RTA BANDWIDTH [1/1 | 1/3]
S151
ALL
Number of Allocated RAM Slots
S152
ALL
ELECTROSTATIC ACTUATOR
OFF/ON
S153
ALL
HEATER LINE OFF/ON
2/6/17
A -39
S154
ALL
MODEM MODE
S155
ALL
MODEM DIAL OUT MODE
S156
ALL
MODEM PHONE NUMBER
S157
ALL
Monitor Number
S158
ALL
MODEM INIT STRING
Special Functions - Advanced use only. Remaining commands are not available on SETUP
menu.
S159-166 Reserved settings
S167
ALL
RELATIVE LEVEL REFERENCE
S174
ALL
UNFORMATTED REPORTS
(x)
S175 Reserved setting
S176
ALL
PRINTER TYPE
(x)
S177
ALL
DATA REPORT
(x)
S178
SSA, LOG
R/S AND CAL LOG
(x)
S179
ALL
SETUP REPORT
(x)
S180
LOG
RMS HISTOGRAM TABLE
(x)
S181
LOG
RMS HISTOGRAM TABLE LOWEST VALUE
(n)
S182
LOG
RMS HISTOGRAM TABLE HIGHEST VALUE
(n)
S183
LOG
RMS HISTOGRAM TABLE RESOLUTION
(x)
S184
LOG
PEAK-II HISTOGRAM TABLE
(x)
S185
LOG
PEAK-II HISTOGRAM TABLE
LOWEST VALUE
(n)
A-40
824 Reference Manual
2/6/17
S186
LOG
PEAK-II HISTOGRAM TABLE
HIGHEST VALUE
(n)
S187
LOG
PEAK-II HISTOGRAM TABLE
RESOL
(x)
S188
LOG
PEAK-I HISTOGRAM TABLE
(x)
S188
RTA
RTAf PRINT LIVE SUMMARY OR
EVENT DATA
[NO, YES]
S189
LOG
PEAK-I HISTOGRAM TABLE LOW
VALUE
(n)
S189
RTA
RTAf PRINT LEQ SUMMARY OR
EVENT DATA
[NO, YES]
S190
LOG
PEAK-I HISTOGRAM TABLE HI
VALUE
(n)
S190
RTA
RTAf PRINT MAX SUMMARY OR
EVENT DATA
[NO, YES]
S191
LOG
PEAK-I HISTOGRAM TABLE
RESOL
(x)
S191
RTA
RTAf PRINT MIN SUMMARY OR
EVENT DATA
[NO, YES]
S192
LOG
EXCD REPORT
(x)
S192
RTA
EVENT WORKING REPORT
ENABLE
[NO, SHORT, LONG]
S193
LOG, RTA
EXCD REPORT LOWEST RECORD
(n)
S194
LOG, RTA
EXCD REPORT HIGHEST RECORD
(n)
S195
SSA, ISM,
LOG
INTV REPORT
(x)
S195
RTA
SPATIAL AVERAGE HISTORY
REPORT ENABLE
[NO, YES]
S196
SSA, ISM,
LOG
INTV REPORT LOWEST RECORD
(n)
2/6/17
A -41
S197
SSA, ISM,
LOG
INTV REPORT HIGHEST RECORD
(n)
S198
LOG
HIST REPORT
(x)
S199
LOG
HIST REPORT LOWEST RECORD
(n)
S199
RTA
EVENT BYTIME REPORT LOWEST RECORD
[0 . . . 65535]
S200
LOG
HIST REPORT HIGHEST RECORD
(n)
S200
RTA
EVENT BYTIME REPORT HIGHEST RECORD
S201
LOG
DAILY NOISE REPORT
(x)
S201
RTA
TEMPORARY NOTE FIELD FOR
SPATIAL AVERAGE
[0 . . . 65535]
S202
ALL
CALIBRATION MODE [Off | Check |
Change | Chk NF]
S203
ALL
UNLOCK PASSWORD
S204
ALL
SETUP FILENAME
S205
ALL
ENABLE ERROR CHECKING I/O
Error Checking I/O
The error checking I/O protocol verifies that commands and
data are transferred without errors.
•
•
To enable error checking the @ command or S205,1
command is used.
To disable error checking two <CR> characters in a row
may be sent (if not in the Modem Mode) or the S205, 0F
command is sent.
The “F” is the check character for the S205, 0 command. A
detailed description of the protocol is available from Larson
A-42
824 Reference Manual
2/6/17
Davis and the latest revisions of software utilize the
protocol.
S206 Reserved setting
S207
ALL
NOISE FLOOR LEVEL
This setting is set to the noise floor of the instrument so that
it can properly indicate “Near Noise Floor” messages when
within 10dB of the noise floor. It is also used with NF
Compensate, Q208, which will place the System 824 in an
extended Linearity Range Mode. The true noise floor of the
entire system must be measured and entered in Q207. This
will vary with the selected input weighting or microphone
sensitivity. An equivalent microphone capacitance can be
used after calibration to determine the noise floor. It may
also be possible to remove the microphone bias to obtain this
value. When properly set up the linearity range can be
increased by 10dB.
NOTE: The mode is always turned off
with a CAL Change.
S208
SSA, ISM,
LOG
NOISE FLOOR COMP MODE
S209 Reserved setting
S210
ALL
AUX CONTROL REG
S211
LOG
EXCD RECORD NUMBER
S212
SSA, ISM,
LOG, RTA
INTV RECORD NUMBER
S213
LOG
HIST RECORD NUMBER
S213
RTA
BYTIME HISTORY RECORD
S214
LOG
RUN-LOG RECORD NUMBER
S215
LOG
DAILY RECORD NUMBER
S216
LOG
CALIBRATION RECORD NUMBER
2/6/17
(NNNNN)
A -43
S217
LOG
HISTOGRAM TABLE LEVEL
S218
ALL
Data File Record Number
S219
ALL
Graph Vertical Scale, dB per pixel
S220
ALL
Graph Base Level (range from -99 to
+999)
S221
ALL
Request to send Output Control Mode
S224
LOG, RTA
Start Level (nn) for Ln and ExTH
S227
ALL
OVERALL CALIBRATION OFFSET
(uses 225.48 lock)
S230
ALL
BIAS OFFSET - For High Range Calibration (uses 225.48 lock)
S231 Reserved setting
S232
ALL
Temperature Calibration (Cal level
must be 225.48)
S233
ALL
SERIAL NUMBER Entry (secured setting)
S234
ALL
Model Number Entry (secured setting)
S235
ALL
Invalid Setting’s data block
A-44
824 Reference Manual
2/6/17
RTA Settings Commands
S53
RTA
Filter Bandwidth [1/1 | 1/3]
S54
RTA
Detector [Lin | Exp] Time Weighting
S55
RTA
Linear Detector Time (ss.ssss) seconds
S56
RTA
Exponential Detector Time [1/64 | 1/32
| 1/16 | ... 32 | 64]
S57
RTA
Exponential Detector Sample Rate [1/2
| 1/8]
S58
RTA
Auto-Store Records [No | Yes]
S59
RTA
Event By-Time Pretrigger Samples
(nnn)
S60
RTA
Event Triggering Enable [No | Yes]
S61
RTA
Trigger Source Level [12.5 | 16.0 |... |
16.0K | 20.0K | Flat] Hz
S62
RTA
Store By-Time Samples of Event [No |
Yes]
S63
RTA
Arm Mode [... | L < | L = | Input | Time |
Count]
S64
RTA
Arm Level (nnn.n) dB
S65
RTA
Arm Time (ss.ssss) Sec (for Level and
Time Arm Mode Conditions)
S66
RTA
Arm Samples (nnnnn)
S67
RTA
Arm Logic Input TRUE Level [Low |
High]
S68
RTA
Trigger Mode [... | L < | L = | Input |
Time | Count]
S69
RTA
Trigger Level (nnn.n) dB
S70
RTA
Trigger Time (ss.ssss) Sec
2/6/17
A -45
S71
RTA
Trigger Samples (nnnnn)
S72
RTA
Trigger Logic Input TRUE Level [Low
| High]
S73
RTA
Run via Logic Input [no, Yes]
S74
RTA
Run Mode Logic Input TRUE Level
[Low | High]
S75
RTA
Logic Outputs Control Setting (bit
mapped word: 3 outputs X 5 states)
S76
RTA
End Mode [Never| L < | L = | Input |
Time | Count]
S77
RTA
End Level (nnn.n) dB
S78
RTA
End Time (ss.ssss) Sec
S79
RTA
End Samples (nnnnn)
S80
RTA
End Logic Input TRUE Level [Low |
High]
S81
RTA
End Then, Repeat Mode [Stop | Repeat
| Average]
S82
RTA
Repeat Count (nnn) 0 to 255 times
S83
RTA
Average Count (n) 0 to 9 times
S84
RTA
Annunciator (cccccccc) if right digit is
numeric it will auto-increment
S85
RTA
RT-60 calculation dB down setting [5 |
10 | 20 | 30]
S86
RTA
Horizontal Graph Scaling [1, 2, 3, 4 ... ,
725, 1024]
S188
RTA
Print Live Summary or Event Data [No
| Yes]
S189
RTA
Print Leq Summary or Event Data [No |
Yes]
A-46
824 Reference Manual
2/6/17
S190
RTA
Print Max Summary or Event Data [No
| Yes]
S191
RTA
Print Min Summary or Event Data [No
| Yes]
S192
RTA
Event working report enable [No |
Short | Long]
S199
RTA
Event ByTime REPORT LOWEST
RECORD
nnnnn
S200
RTA
Event ByTime REPORT HIGHEST
RECORD
nnnnn
S213
RTA
ByTime History Record
(nnnnn)
S195
RTA
Spatial Average History Report Enable
S201
RTA
Temporary Note Field for Spatial Average
S139
RTA
FFT Repeat on Count complete [0 =
No, 1 = Yes]
S138
RTA
FFT Enable Overload Skipping [0 =
No, 1 = Yes]
History Records
Histories are records of stored data based on time or a
particular event. One record is available at a time. The
current record number is selected by using the Advance,
Backup, and Find commands (see below) or the Setting
S211 through S217.
The various histories of the System 824 are each accessed in
a similar fashion. The Find command is the primary method
of locating a history record for random (nonsequential)
access. For example, to find the one hundred twenty-fifth
Exceedance record you send the command F125,1 <cr>
where the [,1] specifies that it is an Exceedance record to be
found (as defined in the “history_number” column below).
2/6/17
A -47
The Advance and Backup commands are generally used
next. They extract data after the initial find command.
The Find command takes longer to execute as the record
number increases in size, therefore, for sequential data
extraction locate the first desired record with the Find
command and then use the Advance command. The
[,relative_rec] option can be used to retrieve data forward or
backward from the current record number without changing
that record number; it is a signed 8-bit value, i.e. 1 to 127 is
positive 1 to 127 while 128 to 255 is -128 to -1 respectively.
Refer to settings 211 through 217 to query the current record
number. Setting these to a desired record number is an
alternate form of the Find command.
Brackets in the syntax indicate optional characters and
operands.
<cr> = carriage return; <lf> = line feed
Types of History
Each history is assigned a number (history_number) so that
it can be identified explicitly with the Advance, Backup, and
Find commands and is shown below.
Denoted in syntax by history_number:
1=Exceedance (E)
2=Interval (I)
3=Daily (D)
4=Run Log (L)
5=Calibration (C)
6=Time (H)
7=Histogram Table (T)
Advance
Advance a number of records from present record number. If
no num_record (number of records) is provided, 1 is
assumed.
Syntax
Response
A[dvance][num_record][, history_number]
<cr><lf>
Example: A
Example: A5
Example: A9,5
Advance current history 1 record
Advance current history 5 records
Advances calibration history by 9 records
A-48
824 Reference Manual
2/6/17
Backup
Backup a number of records from present record number. If
no num_record (number of records) is provided, 1 is
assumed.
Syntax
Response
B[ackup][num_record][, history_number]
<cr><lf>
Example: B
Example: B5
Example: B9,5
Backup current history by 1 record
Backup current history by 5 records
Backup the calibration history by 9 records
from the current calibration history
Find
Find record number directly.
Syntax
Response
F[ind]num_record[, history_number]
<cr><lf>
Example: F9,5
Locates calibration history record 9
Generally you use the Find command to get to the first
record (F1,2) and the Advance command (A) to move up
through the records.
History Data Variables
Exceedance History Variables
Brackets in the syntax indicate optional characters and
operands.
Syntax
Response
E[xceedance]var_no
Excd_var
Example: E9
__2 (Overload count from current record)
2/6/17
A -49
Commands
Instrument
Type
Description
Commnet
E1
LOG RTA
Date and Time of Occurrence
ddmmmyy hh:mm:ss
E2
LOG, RTA
Duration
hh:mm:ss / mm:ss.ss
E3
LOG
TWA
nnn.n dB
E3,f
RTA
Leq Filter
E4
LOG
SEL
E4,f
RTA
Max filter
E5
LOG
Lmax
E5,f
RTA
Min Filter
E6
LOG
Lpeak
E6
RTA
Overload
E7
LOG
UnWeighted Peak
E7
RTA
Pretrigger Samples
E8
LOG
Peak Exceedance Count
E8
RTA
Trigger Samples
E9
LOG
Overload Counts
E9
RTA
Total Samples
E0
LOG
Illegal Indication
E10
RTA
Pre/ Post Trigger indication
E11,n
RTA
Sets ByTime Sample
E12,f
RTA
By Time Sample Filter Level
E13,n
RTA
ByTime Sample Time
A-50
824 Reference Manual
nnn.n dB
nnn.n dB
nnn.n dB
nnn.n dB
nnn
nnn
BEEP +”ILLEGAL”
If n<0, no change just
report current sample
2/6/17
Commands
Instrument
Type
Description
E14,n
RTA
By Time Sample Duration
E15,n
RTA
By Time Overload
E16
RTA
RT60 calculation at current filter.
Filter set by E 3, E 4, E 5, or E 12.
E17
LOG
Excd Time-Hist Samples
E17,n
RTA
Extracts ByTime History and
returns nothing
E18[n]
LOG
Excd Time-History
E18
RTA
RT60 delta time.
Commnet
nnn
nnn.n dB
NOTE: Value is determined by prior E 16, or E
17.
E19<,n>
LOG
Excd T.H. Time
-sss.ss
E20<,n>
LOG
Excd T.H. Number
-nnn
E21<,n>
LOG
Excd T.H. Bargraph
*********************
*
E101
LOG
Excd Macro Variables 1-10, 25
Macro
E102
LOG
Excd Macro Time-Hist 17, 18...
Macro
Interval History Variables (“I” Commands)
The Interval History is a long-duration time history of
statistical data. It is enabled by Setting 83, Interval Enable
[No|Yes] (see Settings 83 through 90). The period of the
2/6/17
A -51
interval is selectable from one second up to 99 hours, 59
minutes, and 59 seconds (99:59:59).
Brackets in the syntax indicate optional characters and
operands.
Syntax
Response
I[nterval]var_no
Intv_var
Examples:
I1
I 1,-5
I1,5
01Jan1997 01:25:00
01Jan1997 01:20:00 (from 5 previous)
01Jan1997 01:30:00 (from 5 after)
The time syncing feature can be used to synchronize the
interval history records to the instruments real-time clock. If
the Interval Period is set to the time shown in the first
column below, the first interval of each new measurement
will end at the real time indicated in the second column (the
hh means any hour and the hh:m means any hour and tens of
minutes). All subsequent intervals will now be synchronized
to the real-time clock:
A-52
Intv
Period
Sync On
Sync to nearest
01:00
hh:00
hour
00:30
hh:00, hh:30
half hour (30 minutes)
00:20
hh:00, hh:20, hh:40
one-third hour (20 minutes)
00:15
hh:00, hh:15, hh:30, hh:45
one-fourth hour (15 minutes)
00:10
hh:m0
one-sixth hour (10 minutes)
00:05
hh:m0, hh:m5
one-twelfth hour (5 minutes)
00:0x
hh:mm
minute
824 Reference Manual
2/6/17
Commands
Instrument
Type
Description
Comments
I0, I101
RTA
or variable greater that 4 will run
macro by default.
I1
SSA, LOG,
RTA, FFT,
TAL
Date and Time of Occurrence
ddmmmyy hh:mm:ss
I2
SSA, LOG,
TAL
Duration
hh:mm:ss / mm:ss.ss
I2
RTA
Number of Samples Averaged
nnnn
I2
FFT
Count
nnn
I3
SSA, LOG
TWA
nnn.n dB
I3
RTA
Spectral or Flat Level (n=ANSI
filter#)
nnn.n dB
I3
FFT
OVER LOAD
cccc
I3
TAL
Overload Counts
nnn
I4
SSA, LOG
SEL
nnn.n dB
I4
RTA
Note Field
cccccccc
I4
FFT
Overall Level
nnn.n
I4
TAL
Mode [SLM | RTA | Tonal]
I5
SSA, LOG
Lmin
nnn.n dB
I5,n
FFT
FFT Line Level (n=0 to 400)
nnn.n
I5,n
RTA
RTA Live Spectrum Level
nnn.n dB
I6,n
RTA
RTA Leq Spectrum Level
nnn.n dB
I6
SSA, LOG
Lmax
nnn.n dB
I7
SSA, LOG
Lpeak
nnn.n dB
2/6/17
A -53
Commands
Instrument
Type
Description
Comments
I8
SSA, LOG
UnWeighted Peak
nnn.n dB
I9
SSA, LOG
RMS Exceedance Count
nnn
I10
SSA, LOG
Peak Exceedance Count
nnn
I11
SSA, LOG
UnWeighted Peak Excd Count
nnn
I 12
SSA, LOG
Overload Counts
nnn
I13
LOG
Intv Ln 1 Percent
nn
I14
LOG
Intv Ln 1 Level (dB)
nnn.n
I15
LOG
Intv Ln 2 Percent
nn
I16
LOG
Intv Ln 2 Level (dB)
nnn.n
I17
LOG
Intv Ln 3 Percent
nn
I18
LOG
Intv Ln 3Level (dB)
nnn.n
I19
LOG
Intv Ln 4 Percent
nn
I20
LOG
Intv Ln 4 Level (dB)
nnn.n
I21
LOG
Intv Ln 5 Percent
nn
I22
LOG
Intv Ln 5 Level (dB)
nnn.n
I23
LOG
Intv Ln 6 Percent
nn
I24
LOG
Intv Ln 6 Level (dB)
nnn.n
I37,n
SSA
RTA Filter Leq (n = ANSI filter#)
nnn.n dB
I38,n
SSA
RTA Filter Leq (n = ANSI filter#)
nnn.n dB
I101
SSA, LOG
Intv Macro Variables
1-12, 37-38
I101
RTA
Macro 1 to 4
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824 Reference Manual
2/6/17
“I” Commands for Basic SLM Mode:
Commands
Instrument
Type
Description
Comments
I5,n
SSA, LOG
Any SPL; n=1 to 9
nnn.n
I6,n
SSA, LOG
Any Max; n=1 to 9
nnn.n
I7,n
SSA, LOG
Any Leq; n=1 to 9
nnn.n
I8
SSA, LOG
LAFTM5 (Takt5 A Fast)
nnn.n
I9
SSA, LOG
Intv Impulse A Leq (dB)
nnn.n
I10
SSA, LOG
Intv Ln 1 Percent
nn
I11
SSA, LOG
Intv Ln 1 Level (dB)
nnn.n
I12
SSA, LOG
Intv Ln 2 Percent
nn
I13
SSA, LOG
Intv Ln 2 Level (dB)
nnn.n
I14
SSA, LOG
Intv Ln 3 Percent
nn
I15
SSA, LOG
Intv Ln 3 Level (dB)
nnn.n
I16
SSA, LOG
Intv Ln 4 Percent
nn
I17
SSA, LOG
Intv Ln 4 Level (dB)
nnn.n
I18
SSA, LOG
Intv Ln 5 Percent
nn
I19
SSA, LOG
Intv Ln 5 Level (dB)
nnn.n
I20
SSA, LOG
Intv Ln 6 Percent
nn
I21
SSA, LOG
Intv Ln 6 Level (dB)
nnn.n
I22,n
SSA, LOG
Differences 0 to 2
[LAFTM5 - LAeq | LCeq - LAeq |
LAIeq - LAeq]
2/6/17
A -55
“I” Commands for Tonal Mode:
Commands
Instrument
Type
Description
Comments
I5
TAL
Ftone
nnnnn Hz
I6
TAL
Dfc
nnnnn Hz
I7
TAL
Ltone
nnn.n dB
I8
TAL
Lgroup
nnn.n dB
I9
TAL
Ltone-Lgroup
nnn.n dB
Daily History Variables - (D1-D102)
Brackets in the syntax indicate optional characters and
operands.
Syntax
Response
D[aily]var_no[,hour]
daily_var
Example: D5, 5
hourly noise level for hour 5 to 5:59:59 a.m.
A-56
D1
LOG
Date
ddd ddmmmyyyy
D2
LOG
Daily Leq
nnn.n dB
D3
LOG
Daily LDN
nnn.n dB
D4
LOG
Daily CNEL
nnn.n dB
D 5,hn
LOG
HNL (for hour 0-23)
nnn.n dB
D 6,hn
LOG
HNL partial hour indicator
c
D7
LOG
Daily Lmin
nnn.n dB
D8
LOG
Daily Lmax
nnn.n dB
824 Reference Manual
2/6/17
2/6/17
D9
LOG
Daily Lpeak
nnn.n dB
D 10
LOG
Daily Luwpk
nnn.n dB
D 11
LOG
Daily Run Time
hh:mm:ss | mm:ss.ss
D 19
LOG
Daily Ln Table in hexadecimal
hhhhhh, hhhhhh,...hhhhhh
<ih>
D 20
LOG
Intv Ln 1 Percent
nn
D 21
LOG
Intv Ln 1 Level (dB)
nnn.n
D 22
LOG
Intv Ln 2 Percent
nn
D 23
LOG
Intv Ln 2 Level (dB)
nnn.n
D 24
LOG
Intv Ln 3 Percent
nn
D 25
LOG
Intv Ln 3Level (dB)
nnn.n
D 26
LOG
Intv Ln 4 Percent
nn
D 27
LOG
Intv Ln 4 Level (dB)
nnn.n
D 28
LOG
Intv Ln 5 Percent
nn
D 29
LOG
Intv Ln 5 Level (dB)
nnn.n
D 30
LOG
Intv Ln 6 Percent
nn
D 31
LOG
Intv Ln 6 Level (dB)
nnn.n
D 32,h
LOG
Intv Ln 1 Percent
nn
D 33,h
LOG
Hourly EXCD Leq
(h=hour=0-23)
nnn.n dB
D 101
LOG
Hourly BkGd Leq (h=hour=023)
nnn.n dB
D 102
LOG
Daily HNLs 5(0-23),6(0-23)
Macro
A -57
Run Log Variables (SSA, ISM, LOG, TAL)
Brackets in the syntax indicate optional characters and
operands.
Syntax
Response
L[og]var_nolog_var
Example: L1
Run/Stop number
L1
Run/Stop Number
nnnnn
L2
Run/Stop Type
(RUN/STOP/CONT/PAUSE/MARK)
L3
Cause
(TIMER/KEY/A:D-n/HALT/INTV/
BATT)
L4
Day, Date and Time
ddd ddmmmyyyy hh:mm:ss
L 101
Run-Log Macro Variables L1-L5
Macro
Calibration History Variables (LOG)
Brackets in the syntax indicate optional characters.
Syntax
Response
C[alibration]var_no
cal_var
Example: C1
114.0 (checked level)
C1
Checked Level
nnn.n
C2
Day, Date and Time
ddd ddmmmyyyy hh:mm:ss
C3
Calibration Mode
[Manual/Auto]
A-58
824 Reference Manual
2/6/17
C4
Cal Status
[OK/Bad]
C 101
Cal Variables 1-4
Macro
Time History Variables (SSA, LOG, TAL)
Brackets in the syntax indicate optional characters and
operands.
H1
SSA, LOG,
TAL
Leq (RMS Level)
nnn.n dB
H2
LOG
Other level (Pk-I, Pk-II, or Lmax)
nnn.n
If Other Level is set to Advc then
“___”
H3
SSA, LOG,
TAL
Run time of sample
hhhhh:mm/hh:mm:ss/mm:ss.ss
H4
SSA, LOG,
TAL
HISTORY BARGRAPH
==========-----
H 5,
n
SSA, LOG,
TAL
Return the advanced value where ‘n’
comes from a list of available levels
The optional parameter ‘n’ is
available only when advanced
time history is enabled. When
‘n’is omitted or 0, all enabled
values are transmitted
H 6,
n
SSA, LOG,
TAL
Return descriptive text for the
advanced level
‘n’ is an optional parameter, when
it is omitted or equals 0, the
descriptive text for all enabled
levels is returned.
H 7,
n
SSA
Return RTA Leq/Live data from an
advanced time history.
‘n’ is the ANSI filter number for
requesting a single filter level.
When ‘n’ is omitted or equals 0,
all filter levels are transmitted.
2/6/17
A -59
H
101
SSA, LOG,
TAL
Same as doing an H 1 + H 5, 0
H
102
SSA, LOG,
TAL
Same as doing an H 1 and H 6, 0
For the LOG instrument type H5 and H6 are for when
“Other Level” setting is set to [Advc] to enable the advanced
time history.
Time History Variables (SSA, LOG, TAL)
Brackets in the syntax indicate optional characters and
operands.
Syntax
Response
H[istory]var_no
time_var
H2
123.4 (Peak level in current record)
H1
Leq (RMS Level)
nnn.n dB ‘n’
H2
Peak Level
nnn.n dB
H3
Run Time of Sample (calc)
hhhhh:mm/hh:mm:ss/mm:ss.ss
H4
HISTORY BARGRAPH
==========-----
Histogram Table Variables
Brackets in the syntax indicate optional characters and
operands.
Table:
•
•
•
A-60
1=RMS,
2=Peak,
3=Unweighted Peak.
824 Reference Manual
2/6/17
Default is last used table or RMS.
Syntax
Response
T[able]var_no[, table]
table_var
Example: T1,1
-75.0 (RMS current bin level)
T 1 [na]
LOG
Level of current bin
nnn.n dB
T 2 [n]
LOG
Count of samples
nnnnnc (c= K or M for Kilo or
Mega)
T 3 [n]
LOG
Percent of total
nnn.nn%
T 5 [ n]
LOG
Prints the accumulated time for the
current level/bin. The table number is
optional.
hhhhh:mm:ss.s
T n+64
LOG
Shows total of bins less than this level
T
n+128
LOG
Shows total of bins greater than this
level, plus resolution
a. Where n equals the table number: 1-RMS, 2-Peak, & 3-UnWeighted Peak.
Print Command
Brackets in the syntax indicate optional characters.
<cr> = carriage return; <lf> = line feed
Syntax
Response
P[rint]print_no
<cr><lf>
2/6/17
A -61
Example: P1
Data Report is printed to computer.
P9
S177,1
S178,1
S192,1
P100
(1) sets all report enables in setup to [No]
(2) sets the Data report, Run-log, and EXCD report enables
(short) to [Yes] and
(3) begins printing to the computer
Syntax
Instrument
Type
Description
P0
ISM, SSA,
LOG, RTA
Tailored Report (Formatted from normal setup settings 89-113)
P1
ISM, SSA,
LOG, RTA
Data Report
P2
SSA, LOG
Data & Histograms
P3
SSA, LOG
Short Full Report (Histories with SHORT option)
P4
SSA, LOG
Long Full Report (Histories with LONG option)
P9
ISM, SSA,
LOG, RTA
All Report Enables Turned OFF
P 10
SSA, LOG
Select All except Histograms in Unformatted Style
P 11
SSA, LOG
Select All including Histograms in Unformatted Style
P 100
ISM, SSA,
LOG, RTA
Begin Printing through current I/O command channel (See X100 Command)
P 101
ISM, SSA,
LOG, RTA
Begin Printing through channel selected by “Print Command”
P 999
ISM, SSA,
LOG, RTA
Abort Printing
A-62
824 Reference Manual
2/6/17
X 100
ALL
XMODEM Begin Printing (same as P100 except through the XMODEM
communication protocol) Use with UnFormatted Reports to download a
file to be viewed in a spreadsheet program. Also use this to download
reports for printing on a computer’s printer, rather than directly from the
824; this lets reports to be printed on a nice laser printer connected to a
computer without having to disconnect it from the computer.
^X^X
ISM, SSA,
LOG, RTA
CANcel transfer mode, 2 in a row (ASCII <CAN> or CHR$(24))
Error Messages and Warnings
The code listed is the number provided by R98.
All error messages begin with: CHR$(7), “ERROR - ”
Error
Code
Message
1
“COUNT OVERFLOW”
2
“EXPONENTIAL OVERFLOW”
3
“RTX TASK SELECT”
4
“BAD EXCHANGE RATE”
5
“UNKNOWN IRQ”
6
“WATCHDOG RESET”
7
“RAM BANK”
8
“OPCODE ERROR”
2/6/17
A -63
All warning messages begin with: CHR$(7), “WARNING ”
Warning
Code
Message
128
“Out of Memory”
129
“Divide by Zero”
130
“Battery Low”
131
“POWER FAILURE”
132
“External Power Failure”
133
“Power Off”
134
“Time Not Set!”
135
“Timer Pending”
136
“Printer is Busy”
137
“DPC Format”
138
“Key No Effect”
139
“Stop Required”
140
“Setting Wrong”
141
“Overall Reset Required”
142
“OPEN #”
143
“Already Open”
144
“No History Yet”
145
“At End of History”
146
“At Start of History”
147
“History Format Bad”
A-64
824 Reference Manual
2/6/17
148
“EEPROM Fault”
149
“Out of Memory”
150
“Memory was Lost”
151
“Unimplemented”
152
“System Locked”
153
“A:D Stack Full”
154
“A:D Over-Run”
155
“Serial Port Framing”
156
“Serial Port Line Noisy”
157
“Serial Port Over-Run”
158
“Unknown I/O Command”
159
“Operand 1 Range”
160
“Operand 2 Range”
161
“I/O Overflow”
162
“Can’t Calibrate”
163
“Calibration Invalid”
164
“Analog Calibration Bad”: often an indication of a faulty EPRM
165
“ID is Active”
166
“ID is in ROM’”
167
“ID is Read Only”
168
“ID is in a File”
169
“ID has Changed”
170
“ID Space Full”
171
“Purge Required”
2/6/17
A -65
172
“No Data”
173
“Not Available”
174
“Demo Mode”
175
“Setting Conflict”
Modem Control Mode (All Instruments)
The modem control mode enables the Model 824 to
automatically dial out upon an exceedance or a low memory
condition. This mode also enables the Model 824 to answer
the phone so that instructions can be received. The modem
must be Hayes (TM) compatible and set to respond to
commands using numeric codes (non-verboses).
Modem Mode
If the Modem Mode is [Yes], the Model 824 will dial the
Phone# on the events selected by the Dial Out Mode defined
below.
Dial Out Mode
•
None: The Model 824 will not dial a computer for any
reason.
Excd: The Model 824 will dial a computer to report
when an illegal exceedance is logged into memory. An
illegal exceedance is when Excd Lmax > RMS Excd
Level 2. The phone will also be dialed if the memory is
low.
Phone#: The valid characters in Phone# are those recognized by the modem to which the Model 824 is attached
and generally include:
•
•
A-66
W
will wait for another dial tone
P
selects pulse dialing
824 Reference Manual
2/6/17
T
selects tone dialing
,
will pause dialing for 2 s
space or -
used to make the number more readable.
T9W 1-412-5551212
indicates to use tone dialing, dial 9
for an outside line, wait until the dial
tone is detected, and then dial the
number.
Monitor Number
The monitor number is used to specifically address the
monitor.
824 Phone Dialing Procedure
The Model 824 dialing process is as follows:
Step 1
The Model 824 recognizes an exceedance or low
memory condition.
Example: 824 sends: ATDT 1555-1234(Enter)
Step 2
The Model 824 asks the modem to dial the phone
number.
Modem
(Enter)
Step 3
The modem informs the Model 824 that a connection has been made. The Model 824 modifies its
baud rate to that of the connected modem. If the
connection is unsuccessful, the procedure is
retried in 4 min.
Step 4
The Model 824 sends the following announcement: “824: 824A0123:001:2” (enter), where
(0123) is the Model 824’s serial number, (001) is
the monitor number entered, and (2) is a flag: 1Alarm 2-Exceedance 4-Low Memory. More than
one of these can be set at a time, in which case x is
the sum of all set flags.
2/6/17
sends:
824A0123:001:2
A -67
Computer
824A0123:11111111
sends:
824 sends: “Ready”
Step 5
The Model 824 awaits a response code, which
should be: “824A0123:11111111” (enter), where
(0123) is the Model 824’s serial number and
(11111111) is the Lock Combination (setting 28)
which is required whether or not the Model 824 is
currently locked. If the response is incorrect, the
announcement is resent. Four chances are given to
respond correctly. A “3 cr” sequence will cause
the Model 824 to hang up.
Step 6
When a correct response is received, the Model
824 indicates it is ready to send data when
requested with “824:Ready”(enter).
Model 824 Answering Procedure
Step 1
The modem informs the Model 824 that a
connection has been requested; that is, the phone
is ringing.
Step 2
The Model 824 answers the phone.
Modem sends: 824A0123:001:0
Step 3
The modem informs the Model 824 that a connection has been made. The Model 824 modifies its
baud rate to that of the connected modem. If the
connection is unsuccessful, the procedure is
retried in 4 min.
Modem sends: 10 (enter)
Step 4
The Model 824 sends the following announcement: “824:824A0123:001:0” (enter), where
(0123) is the Model 824’s serial number, (001) is
the monitor number entered, and (0) is a flag: 1Alarm 2-Exceedance 4-Low Memory. More than
one of these can be set at a time, in which case x is
the sum of all set flags.
Step 5
The Model 824 awaits a response code, which
should be: “824A0123:11111111” (enter), where
(0123) is the Model 824’s serial number and
Modem sends: 2
Computer
824A0123:11111111
A-68
sends:
824 Reference Manual
2/6/17
(11111111) is the Lock Combination (setting 28)
which is required whether or not the Model 824 is
currently locked. If the response is incorrect, the
announcement is resent. Four chances are given to
respond correctly. A “3 cr” sequence will cause
the Model 824 to hang up.
824 sends: “Ready”
Step 6
When a correct response is received, the Model
824 indicates it is ready to send data when
requested with “824: Ready” (enter).
Each line ends with a <CR> and line feed <LF>.
Unsupported Miscellaneous Commands
NOTE: Use of these commands is up to
the discretion of the programmer, they
are considered undocumented and
unsupported. Larson Davis makes NO
warranties for their proper operation
and is unable to support them with further documentation or through customer
support. They are used by proprietary
Larson Davis software and are documented here on an as-is basis for those
who may desire to explore, unaided,
these advanced features.
The operation of these commands is subject to change
without notice of any kind.
X 16x
XMODEM binary data dump, x = bit flags;
Add 1 to 'x' to automatically reset histories at completion of transfer
Add 2 to 'x' to inhibit the pause just before sending
OverAll data (the pause provides for cohesive data)
Add 4 to 'x' to begin where last download ended (always starts at the beginning of stored
data if not set)
Add 8 to 'x' to disable waiting for acknowledgment at the end of each block transfer
(used with error checking modems, i.e. MNP 4 or V.42)
Add 16 to enable the Xmodem download at 57.6 kilobaud (Comm. Port 1 ONLY). The
resulting binary file structure is undocumented and unsupported.
The advantages of the binary features can be obtained by utilizing Larson Davis software
(turnkey application, data translators or function library support is available).
^X^X
CANcel transfer mode, 2 in a row (ASCII <CAN> or CHR$(24)).
2/6/17
A -69
>a,b
Read 824's memory from address (a) and bank (b)
^
Read Excd T.H. Buffer. This command is used to create an SPL vs. Time plot that is time
cohesive. Resolution is, by default, 1 dB with one byte/sample being sent. Each byte
has 32 added to it to avoid confusion with ASCII control codes, subtract 32 to use. Only
the samples taken since the last read are sent, up to the buffer size of 128 samples. The
time of day is appended to the end of the string to permit time stamping of the SPL
graph. A delimiter byte (ASCII 212 in decimal, which is the letter “T” with 128 added
to it) precedes the time string.
Full resolution including the fractional part of the level is sent if enabled by the M9,1
command. With full resolution, 2 bytes per level are sent. The first byte being the integer portion, which is the same as described above. The second byte is the fractional
portion. it is converted by subtracting 32 from the byte and then dividing it by 128 to
make it a fraction. The fractional part is then added to the integer part to form the level.
@
Enable IO Error Check Scheme. S205,0F or 2 <CR> in a row to disable.
Data File Commands
The &F I/O command reads out information about stored
data or FILES and has facilities to store and recall files.
These work in conjunction with Advance, Backup and Find
to navigate through the File records of this history (just like
Intervals).
&F1
FILE NAME
cccccccc
&F2
FILE EXTENSION (InstType)
ccc
&F3
FILE DESCRIPTION
cccccccccccccccccccccccccccccc
&F4
CURRENT START TIME
ddmmyy hh:mm:ss
&F5
CURRENT END TIME
ddmmyy hh:mm:ss
&F6
OVERALL START TIME
ddmmyy hh:mm:ss
&F7
OVERALL END TIME
ddmmyy hh:mm:ss
&F8
SIZE OF FILE
nnnnnnn
&F101
Read macro &F variables 1 through 8
A-70
824 Reference Manual
2/6/17
&F102
Recall a FILE into active memory
&F103
Store the current data (in active memory) to a
FILE
2/6/17
A -71
Keyboard Simulation
The keys on the 824’s keyboard may be simulated with the
‘K’ I/O command.
Each key is given an ASCII character as shown in the table
below.
A space delimiter following the ‘K’ is required before nonnumeric operands. (i.e. K ;6<)
The keyboard buffer will hold up to 8 keys. (K12345678 is
acceptable).
ASCII Character:
A-72
Key that is simulated:
0
CHECK KEY
1
POWER KEY
2
RESET KEY
3
PAUSE KEY
4
RUN/STOP KEY
5
UP ARROW
6
DOWN ARROW
7
LEFT ARROW
8
RIGHT ARROW
9
FUNCTION KEY #1 (VIEW)
:
FUNCTION KEY #2 (DATA)
;
FUNCTION KEY #3 (SETUP)
<
FUNCTION KEY #4 (TOOLS)
824 Reference Manual
2/6/17
=
FUNCTION KEY #5 (PRINT)
Operation Notes
When using the Logic Input line in the ‘LEVEL’ mode both
I/O and keyboard Runs and Stops are inhibited. If the line is
High the 824 takes data and if the line is Low no data is
taken. The ‘Pause’ mode will pause the data taking process
while the line is high; this may be triggered by high wind
speed. In the ‘Toggle’ mode when the Logic Input line goes
high the 824 toggles between RUN and STOP modes.
2/6/17
A -73
A-74
824 Reference Manual
2/6/17
APPENDIX
B
Integrated Level Calculations
Basic Integrated Level Calculations
The Larson Davis System 824 calculates all of its integrated levels based on equations from IEC standard 804. IEC-804 Section 3.3 defines Leq as follows:
Equivalent continuous A-weighted sound pressure level (also average A-weighted sound pressure
level) is defined as follows
L Aeq,T

  t2


 1 2

2
= 10lg   ---  p A  t dt  p 0 dB
T




 t1
where:
LAeq,T is the equivalent continuous A-weighted sound pressure level re 20 µPa, determined over a
time interval T=t2-t1
pA(t) is the instantaneous A-weighted sound pressure of the sound signal
p0 is the reference sound pressure of 20 µPa
When, a frequency weighting other than A is used, the frequency weighting used shall be included
explicitly in the title and the formula of the quantity, for example equivalent continuous C-weighted
sound pressure level:
2/6/17
B-1
L Ceq,T

  t2

 1 2
2

= 10lg  --- p C  t dt  p 0 dB



T

t

 1

If no frequency weighting is used, the quantity is simply called equivalent continuous sound pressure
level.
The Larson Davis System 824 calculates many time-integrated levels or time-weighted averages
(TWA) based on different parameters and time intervals. They are all designed and programmed to
perform the equation specified in IEC 804 (above) with allowances for the following:
A, C and Flat frequency weighting characteristics
Various interval times, both fixed interval TWAs and variable interval event TWAs
Exchange-rates, or “doubling rates” can be entered that effect certain TWA measurements
Certain TWA measurements include a programmable threshold with only levels above this threshold
contributing to the measurement
The titles for the measurements are designed to indicate the current exchange rate in force: “Leq” is
used to designate TWAs based upon a 3dB exchange rate, “LDOD” (for United States Department of
Defence) is used to designate TWAs based upon a 4dB exchange rate, “LOSHA” (for the United States
Occupational Safety and Health Association) is used to designate TWAs based upon a 5dB exchange
rate, “LAvg” (for average) is used to designate TWAs based upon a 6dB exchange rate.
No attempt is made to meet the IEC-804 requirement to title the TWA by frequency weighting and
time interval within the analyzer’s display or report system. It is represented though, by placing the
weighting designation following the “dB” units indication associated with the numerical output. The
actual measurement time is also provided for each TWA value to fulfil the time interval description
requirements.
For example, the System 824’s Logging SLM Overall-a display shows the current SPL (Sound Pressure Level) in 1/10th decibel (dB) resolution. The actual real-time resolution is 1/32nd dB. The displayed SPL is followed by the text “dB” and then the frequency weighting in effect—set to A in this
example.
The System 824’s Logging SLM Overall-e display shows the overall measurement period and TWA.
In this case the measurement is Leq (because of the 3dB exchange rate). The quantity is A-weighted
and has a measurement elapsed time of 11:43.1 (11 hours, 43 minutes, and 1 second).
B-2
824 Reference Manual
2/6/17
Scrolling SPL history
Current SPL while running or at the time a stop
occurred
The currently-selected frequency weighting for
SPL
The currently-selected detector
Elapsed measurement time, shown as mm:ss.ss,
hh:mm:ss or hhhhh:mm
Overall time weighted average (Leq in this case)
Time-weighted average (TWA) descriptor for
the overall measurement
Overall exchange rate
Overall sound exposure level (SEL)
Elapsed measurement time, shown as mm:ss.ss,
hh:mm:ss or hhhhh:mm
The actual equations used within the analyzers are based on that for IEC-804 and are implemented
according to this equation:
n
L TWA
Ls  

------k

10  – log  n 
= L cal + k  log



s = 1

where:
L(s) is the current SPL at sample s (for measurements that include a threshold, L(s) is set to -× if L(s) is
less than the Threshold Level Lt)
k is the exchange rate constant which is equal to:
10.00 for an exchange rate of 3dB (Leq)
13.29 for an exchange rate of 4dB (LDOD)
2/6/17
B -3
16.61 for an exchange rate of 5dB (LOSHA)
20.00 for an exchange rate of 6dB (LAvg)
n is the total number of samples taken in the measurement; the sample rate is 32 samples per second,
and
Lcal is the calibration offset that corrects for various sensitivities of microphones
Accuracy is maintained by having large fixed point variables for the number of samples and the summation accumulator. The limit of s is 4,294,967,295 samples and is stored in a 32 bit integer variable
within the System 824. This limit is greater than 1553 days or greater than 4 years and 4 months. The
value that can be stored in the summation accumulator, a 96 bit integer, can be the overload level
(maximum allowable signal amplitude into the System 824) for the maximum number of samples.
Using large fixed point variables prevents the inaccuracies obtained in systems based upon floating
point variables.
SEL Calculations
SEL is available for both the overall and current measurements and is calculated using this formula:
n
L TWA
Ls  

------k

10  – log  32 
= L cal + k  log



s = 1

Since the sample rate is 32 samples per second and SEL is based on time in seconds, the log(32) is
subtracted from the log of the accumulation to perform a division by 32. All of the SEL energy values
in the analyzers utilize the Threshold and Exchange Rate settings. Care should be taken when modifying these settings since some standards or governments require SEL to be taken without a Threshold
(set it to zero) and with an Exchange Rate of 3dB.
Dose and Projected Dose Calculations
Dose is a measure of Sound Exposure and is defined in ANSI S1.25 Section 4.7 as:
where:
D(Q) is the percentage criterion exposure for exchange rate Q
TC is the criterion sound duration = 8 hours
B-4
824 Reference Manual
2/6/17
T
L – L c
 ------------q 

100
D  Q  =  ---------  10
 Tc 

dt
0
T is the measurement duration in hours
t is the time in hours
L is the SLOW, (or FAST) A-weighted sound level, a function of time, when the sound level is greater
than or equal to L, or equals -× when the A-weighted sound level is less than Lt
Lt is the threshold sound level specified by the manufacturer
LC is the criterion sound level specified by the manufacturer
Q is the exchange rate in dB, and q = the parameter that determines the exchange rate, where:
q = 10 for a 3dB exchange rate
q = 5/log(2) for a 5dB exchange rate
q = 4/log(2) for a 4dB exchange rate
The factor of 100 in the equation produces a result that is a percentage.
Dose is obtained from the accumulations made for TWA and SEL using the formula:
where,
L(s) is the current SPL at sample s; for measurements that include a threshold L(s) is set to × if L(s) is
less than the Threshold Level Lt
k is the exchange rate constant which is equal to:
10.00 for an exchange rate of 3dB (Leq, or Ý 3dB/log(2))
2/6/17
B -5
n
L 

s
---------- 

Lc
k
log 
10  – ----- – log  T c 115200  + log  100 

 k
s=1


DOSE = 10
%
13.29 for an exchange rate of 4dB (LDOD, or = 4dB/log(2))
16.61 for an exchange rate of 5dB (LOSHA, or = 5dB/log(2))
20.00 for an exchange rate of 6dB (LAvg, or Ý 6dB/log(2)),
n is the total number of samples taken in the measurement; the sample rate is 32 samples per second,
TC is the criterion sound duration as set by the System 824’s “Criterion Time Hours” setting which by
default is set to 8 hours (since the time base for the instrument is 1/32nd samples per second, the number of hours is multiplied by 115200 to make samples per hour—60 minutes/hour times 60 seconds/
minute times 32 samples/sec equals 115200 samples/second)
LC is the criterion sound level as set by the System 824’s “Overall Criterion” or “Current Criterion”
settings
Addition of the term “log(100)” was used to implement the 100 multiplier of the ANSI equation that
creates the percentage. Subtracting the log of the Criterion Time was used to implement the division of
Criterion Time of the ANSI equation.
Projected Dose in the analyzers is obtained with an equation similar to that of Dose except that the
actual duration (time) of the measurement is used rather than a Criterion Time, as thus:
n
PROJDOSE = 10
L 

s
----------

LC
k
log 
10  – ------ – log  n  + log  100 

 k
s=1


%
where the log(n) is the actual time factor, n being the total number of samples taken.
B-6
824 Reference Manual
2/6/17
APPENDIX
C
Technical Specifications
NOTE: Where possible, tests were
performed electrically using an ADP005
microphone adapter (18 pF).
The specifications contained in this chapter are subject to
change without notice. Please refer to calibration and test
results for data on a specific unit.
These specifications are valid for all System 824’s using the
following options:
•
PRM902 preamplifier
•
377B41 (or 377A60) free-field (or random) high sensitivity microphone
•
2540 (or 2559) free-field (or random) normal sensitivity
microphones
Standards Met:
•
ANSI S1.4 - 1985 Type 1
•
IEC 61672-1 Class 1 (tested with 377B41 microphone
only)
•
IEC 60651 - 1979 Type 1
•
IEC 60804 - 1985 Type 1
•
IEC 60651 - 1993 Type 1
•
IEC 60804 - 1993 Type 1
•
IEC 61260 - 1994 Class 1
Declaration of Conformity
Larson Davis Inc. declares that:
Model 824 Sound Level Meter and Realtime
Analyzer
having been tested in representative configuration with:
PRM902 preamplifier, 377B41 microphone and the
2/6/17
C-1
following cables: EXA010 microphone extension cable,
CBL042 AC/DC output cable, CBL006 serial interface cable
is in accordance with the European Community EMC
Directive (2004/108/EC) and the Low Voltage Directive
(2006/95/EC) by meeting the following standards:
•
89/336/EEC The Electromagnetic Compatibility Directive and its amending directives
has been designed and manufactured to the following
specifications:
NOTE: The 824 does not meet IEC
61672-1, IEC60804 or ANSI S1.4
specifications when used with a high
sensitivity microphone (377B41 or
377A60) and a 20 volt bias. The bias is
changed to 20 volts for high range
measurements in the ISM and LOG
modes, and -10dB or -20dB gain in all
other modes.
C-2
•
IEC 61326-1:2005 Electrical equipment for measurement, control, and laboratory use - EMC requirements.
•
IEC 61010-1:2010 Safety requirements for electrical
equipment for measurement, control, and laboratory use
– Part 1: General requirements.
System 824 Main Characteristics:
824 Reference Manual
2/6/17
Class 1 Precision Integrating Sound Level Meter with real-time
1/3 Octave Filters, classified as group X for the emission of,
and susceptibility to, radio frequency fields.
2MB standard memory
Large backlit graphic display (64 X 128 pixels)
Icon-driven graphic user interface
Soft rubber backlit keys
Large dynamic range
RMS Detectors: Slow, Fast, Impulse
Triple Peak Detectors: A, C, FLat
Interval History (statistical)
Time History
Ln statistics (L0.01 through L99.9 available)
Histogram tables
Direct report printouts to laser printer
WindowsTM-based software for setup, control, and high speed
data download and reporting
Advanced WindowsTM-based software packages (optional)
provides data archiving/search capabilities, post-measurement analysis features, and advanced sorting and graphics/
report generation tools.
Multi-tasking processor allows measuring while viewing data,
transferring data, or printing
Programmable Run/Stop timer for automatic measurements
AC/DC outputs to recorder
Field-upgradable firmware: keeps instrument current with the
latest features via ROM disk upgrades
Two-year limited warranty
General Specifications
2/6/17
Reference level:
114.0 dB SPL
Reference level range
ISM Mode: Normal
SSA Mode: 0 dB Gain
Reference frequency:
1000 Hz
Reference direction:
0° for a free field
microphone and 80°
for a random incidence
microphone
Temperature:
± 0.5 dB error
between
-10° C and 50°C
C -3
Storage temperature:
-10°C to 60°C
Humidty:
± 0.5 dB error
between 30 and 90%
relative humidity at
40°C
Equivalent mic
impedance:
18 pF for Larson Davis
1/2” microphone
Range level error:
< ±0.1 dB relative to
the reference range
Calibration procedure: Using a Larson Davis CAL200 or
equivalent calibrator, insert the microphone fully into the
calibrator. Set the calibrator to 114 dB SPL. On the 824 press
the toolsTkey, arrow down to “Calibration” and press the
right arrow rkey. From the calibration menu use the down
arrowd key and highlight “Change”. Press the check c
key to initiate the calibration. The 824 will prompt you to turn
the calibrator on with “Calibrator Active?”. Select “Yes” after
turning the calibrator on and press the check c key. The 824
performs the calibration change.
C-4
Effect of Magnetic
Field:
80 A/m ( 1 Gauss) @
60 Hz produces a
change of < 0.3 dB
SPL - passes Class 1
according to IEC
61672
Vibration Sensitivity:
(worst case)
73.7 dB with linearweighting at 1.0 m/
sec2
referenced to 58.1 dB
Warm-up Time:
45 sec
Digital Display Update
Rate
Four times per second
(0.25 sec between
updates). First display
indication is available
0.25 seconds after
initiation of a
measurement.
Effect of an extension
cable (EXAxxx) on
calibration:
none (up to 500 feet)
824 Reference Manual
2/6/17
AC/DC Output
AC output voltage
range:
±3 Volts peak
DC output voltage
range:
0 to +3 Volts
SPL – Start level
Vo = -------------------------------------------0.028
dB
SPL = Vo  0.028 ------- + Start level
V
AC/DC output
impedance:
~600 Ohms, AC ouput error: <0.1 dB for input
impedances > 52 K Ohms (instrument readings
are not affected by AC or DC output loading)
AC/DC output connector:
3.5mm stereo jack
Power Supply
Batteries:
3 AA alkaline cells or NiMH battery pack
Internal charge
time:
approx. 7 - 10 hours (BAT010 2300 mAH pack)
approx. 6 hours (BAT010 1200 mAH pack)
depending on capacity at time of charge
DC power input
6-15 Volts at 1/2 amp, max.
Typical DC power
150 mA @ 12 Volts
DC power
connector
5.5mm x 2.5mm coaxial power plug
Battery Operating Time (full capacity, continuous operation, reference environmental conditions,
individual cells may vary in performance)
Battery Type
ISM or LOG Mode
SSA Mode
BAT010 1200 mAH NiMH Pack (Supplied prior to January 2005)
BAT010 2300 mAH NiMH Pack (Supplied after January 2005)
4.1 hours
6.5 hours
3 hours
4.5 hours
2/6/17
C -5
Battery Operating Time (full capacity, continuous operation, reference environmental conditions,
individual cells may vary in performance)
Standard Alkaline AA (eg.Duracell MN1500, type LR6)
4.3 hours
2.8 hours
High Drain Rate Alkaline AA (e.g. Duracell Ultra MX1500, type LR6)
> 4.4 hours
4.4 hours
Photo Lithium AA (e.g. Energizer e2 L91)
 7.5 hours
7.5 hours
2000 mAH NiMH AA Fast Recharging
(e.g. Ray-O-Vac I-C3 15-minute charging time)
5.5 - 6.8 hours
4.5 - 5.5 hours
Memory Retention
Memory retention without batteries or
external power
5 minutes minimum
Physical Characteristics
C-6
Length:
9.9 inches
25.1 cm
Width:
3.4 inches
8.6 cm
Depth:
1.6 inches
4.0 cm
Weight:
18 oz
0.51 kg
824 Reference Manual
2/6/17
Resolution
Levels:
0.1dB (0.01 dB via I/O)
Dose:
0.01%
Elapsed time:
Highspeed RTA, as rapid as every 2.5 mS
all other instruments, 0.1 second
Real time clock
1 second
Calendar:
01 Jan 2000 - 31 Dec 2099
Cable Drive Capability (with PRM902 preamp)
Frequencies to 20 kHz:
700 feet
213 meters
Frequencies to 10 kHz:
1000 feet
305 meters
Maximum Input Voltage* (overload)
Gain
VRMS
Vpeak
dBuV
0 dB
2.54
7.2
128
10 dB
0.74
2.1
118
20 dB
0.254
0.72
108
30 dB
0.080
0.227
98
40 dB
0.025
0.072
88
50 dB
0.008
0.023
78
* Absolute maximum AC input voltage: 10Vpp
Permitted DC voltage range: - 3Vdc to + 30Vdc
2/6/17
C -7
Frequency Weightings for ISM, SSA, LOG and TAL instruments
Nominal
Frequency.
Exact
Frequency.
A
Weight
C Weight Flat
Flat with
Random
Incidence
correction
(except
SSA)
Flat with
Random
Incidence
correction
(for SSA)
Electrical
Tolerance
Microphone.
Tolerance
*
10
10.00
-70.4
-14.3
-6.0
-6.0
-0.3
±1.8
±2.2
12.5
12.59
-63.4
-11.2
-4.2
-4.2
-0.2
±1.5
±2.0
16
15.85
-56.7
-8.5
-2.9
-2.9
-0.2
±1.2
±1.8
20
19.95
-50.5
-6.2
-1.9
-1.9
-0.1
±1.0
±1.5
25
25.12
-44.7
-4.4
-1.3
-1.3
-0.1
±0.9
±1.1
31.5
31.62
-39.4
-3.0
-0.8
-0.8
-0.0
±0.7
±0.8
40
39.81
-34.6
-2.0
-0.5
-0.5
-0.0
±0.7
±0.8
50
50.12
-30.2
-1.3
-0.3
-0.3
-0.0
±0.5
±0.5
63
63.10
-26.2
-0.8
-0.2
-0.2
-0.0
±0.5
±0.5
80
79.43
-22.5
-0.5
-0.1
-0.1
-0.0
±0.5
±0.5
100
100.00
-19.1
-0.3
-0.1
-0.1
-0.0
±0.5
±0.5
125
125.00
-16.1
-0.2
0.0
0.0
-0.0
±0.5
±0.5
160
158.50
-13.4
-0.1
0.0
0.0
-0.0
±0.5
±0.5
200
199.50
-10.9
0.0
0.0
0.0
-0.0
±0.5
±0.5
250
251.20
-8.6
0.0
0.0
0.0
-0.0
±0.5
±0.5
315
316.20
-6.6
0.0
0.0
0.0
-0.0
±0.4
±0.6
400
398.10
-4.8
0.0
0.0
0.0
-0.0
±0.4
±0.6
500
501.20
-3.2
0.0
0.0
0.0
-0.0
±0.4
±0.6
630
631.00
-1.9
0.0
0.0
0.0
0.0
±0.4
±0.6
800
794.30
-0.8
0.0
0.0
0.0
0.0
±0.4
±0.6
1000
1000.00
0.0
0.0
0.0
0.0
0.0
±0.4
±0.6
1250
1259.00
0.6
0.0
0.0
0.0
0.0
±0.4
±0.6
1600
1585.00
1.0
-0.1
0.0
0.1
0.1
±0.4
±0.6
2000
1995.00
1.2
-0.2
0.0
0.2
0.2
±0.4
±0.6
2500
2512.00
1.3
-0.3
0.0
0.3
0.3
±0.4
±0.6
3150
3162.00
1.2
-0.5
0.0
0.5
0.5
±0.4
±0.6
4000
3981.00
1.0
-0.8
0.0
0.8
0.8
±0.4
±0.6
5000
5012.00
0.5
-1.3
0.0
1.3
1.3
±0.5
±-1.0
6300
6310.00
-0.1
-2.0
0.0
1,9
1,9
0.5, -0.7
1.0, -1.4
8000
7943.00
-1.1
-3.0
0.0
2.8
2.8
0.5, -1.0
1.0, -2.0
10000
10000.00
-2.5
-4.4
0.0
4.0
4.0
0.7, -1.3
1.3, -2.7
12500
12590.00
-4.3
-6.2
0.0
5.4
5.4
1.0, -2.0
2.0, -4.0
16000
15850.00
-6.6
-8.5
0.0
6.9
6.9
1.0, -3.0
2.0,
20000
19950.00
-9.3
-11.2
0.0
8.1
8.1
1.0, -4.0
2.0,


* Flat frequency response for SSA instrument is extended at the low frequency end when Random Incidence
Correction is enabled.
C-8
824 Reference Manual
2/6/17
Infrasonic Frequency Response
824 Infrasound Response
Frequency (Hz)
0.1
1
10
100
1000
0.0
Attenuation (dB)
10.0
20.0
30.0
40.0
50.0
RTA
SLM
LOG and ISM Mode Specifications
2/6/17
Time weighting:
Slow, Fast, Impulse,
TWA and Peak
Frequency Weightings
A, C and Flat (see table
on page C-7)
Dynamic range:
> 115 dBA (Overload to
noise floor)
Linearity range:
> 105 dBA
Pulse range:
> 108 dBA
RMS noise floor:
< 16 dBA typical (with
PRM902 and 377B41
mic)
Reference range:
Normal range (0 dB
gain)
Exchange rates:
3, 4, 5, or 6 dB
Sample rate:
48,000 Hz
Peak rise time
50 S
C -9
Peak Detector Frequency Response Graph
AC/DC Output (LOG and ISM modes only)
824 Menu
3.5mm Connector Tip
3.5 mm Connector Ring
AC-1 AC-2
Flat AC output
Flat AC output with 30dB
gain
AC-1 DC
Flat AC output
Weighted DC output
AC-1 DC
Flat AC output with 30
dB gain
Weighted DC output
AC-2 AC-1
Flat AC output with 30
dB gain
Flat AC output
NOTE: In low range, all AC outputs will
provide an additional 20 dB of gain
C-10
824 Reference Manual
2/6/17
.
RMS Measurement Range (LOG and ISM modes only)
2/6/17
Electrical
Noise Floor
Low
Limit
High
Limit
Range
Pulse
Range
A-WT (high)
< 22
< 43
151
> 108
> 108
A-WT (normal)
< 12
< 23
131
> 108
> 108
A-WT (low)
< 10
< 20
111
> 91
> 91
C-WT (high)
< 38
< 48
151
> 103
> 103
C-WT (normal)
< 18
< 28
131
> 103
> 103
C-WT (low)
< 14
< 25
111
> 86
> 86
FLAT (high)
< 40
< 50
151
> 101
> 101
FLAT (normal)
< 20
< 30
131
> 101
> 101
FLAT (low)
< 15
< 25
111
> 86
> 86
C -11
NOTE: Ranges are in dBSPL using a
typical 377B41 microphone with a
sensitivity of 44.5 mV/Pa and a 200V
polarization voltage. A 2540 normal
sensitivity microphone produces high
limit values approximately 10.0 dB
higher.
NOTE: Ranges are in dBSPL using a
typical 377B41 microphone with 44.1
mV/Pa sensitivity. The range is measured
between a low limit of peak error > 0.5
dB and a high limit of overload.
C-12
Peak Measurement Range (LOG and ISM modes only)
Low Limit
High Limit
Range
A-WT (high)
73
148
75
A-WT (normal)
53.0
128.0
75.0
A-WT (low)
53.0
108.0
55.0
C-WT (high)
73
148
75
C-WT (normal)
53.0
128.0
75.0
C-WT (low)
53.0
108.0
55.0
FLAT (high)
80
148
68
FLAT (normal)
60.0
128.0
68.0
FLAT (low)
60.0
108.0
48.0
SSA Mode Specifications (IEC 61260 Class 1)
Broadband Overall
time weighting:
Slow, Fast, Impulse,
TWA and Peak
1/3 octave filter time
weighting:
Slow, Fast
Broadband Frequency
Weightings
A, C and Flat (see
table on page C-7)
Dynamic range:
> 93 dBA (overload to
noise floor)
Linearity range:
> 80 dBA
Pulse range:
> 83 dBA
RMS noise floor:
< 33 dBA typical with
PRM902, 377B41
microphone, and 0 dB
gain
Reference level range:
0 dB gain
Exchange rates:
3, 4, 5, or 6 dB
Sample rate:
51,200 Hz
1/3 octave band
frequencies:
12.5 Hz - 20 kHz
824 Reference Manual
2/6/17
Prefilter Frequency
Weightings
A, C and Flat
Filter integrated
response:
 ±0.15dB for all filters.
Real-time operation:
±0.3 dB error for all
filters tested with a
swept sinusoidal input.
Anti-aliasing:
 75 dB
Summation of output
signals:
£ ± 1.0 dB (±0.4 dB
typical)
Flat frequency range:
10 Hz - 20 kHz,
relative attenuation < ±
0.15 dB
Filter type:
Digital
Octave frequency
ratio:
Base 2 (See IEC
61260 Annex A)
AC/DC Output (SSA mode only)
824 Menu
3.5mm Connector Tip
3.5 mm Connector Ring
AC-1 AC-2
Flat AC output
C-weighted AC output
AC-1 DC
Flat AC output
Weighted DC output
AC-2 DC
C-weighted AC output
Weighted DC output
AC-2 AC-1
C-weighted AC output
Flat AC output
NOTE: AC output gain matches the input
gain setting.
2/6/17
C -13
Measurement Range (SSA mode only)
0dB Gain
NF
Start
End
33
32
32
2
3
4
2
3
12
10
15
14
14
48
48
48
45
43
40
40
37
33
32
32
32
32
128
128
128
128
128
128
128
128
128
128
128
128
128
AW
CW
FLA
16.0
31.5
63.0
125
250
500
1000
2000
4000
8000
10dB Gain
Rang
e
80
80
80
83
85
88
88
91
95
96
96
96
96
NF
Start
End
24
23
25
2
1
0
-2
-3
4
2
6
7
7
38
38
38
35
35
33
27
25
25
20
20
20
20
118
118
118
118
118
118
118
118
118
118
118
118
118
20db Gain
Rang
e
80
80
80
83
83
85
91
93
93
98
98
98
98
NOTE: A-weighting, C-weighting, and
Flat are measured to ANSI S1.4 and IEC
60651 standards for SLM linearity. 1/3
octave filters listed are measured to the
IEC 61260 standard for Class 0 linearity
which is ±0.3 dB. The numbers in the
table represent SPL levels with a typical
377B41 microphone which has 44.1 mV/
Pa sensitivity.
C-14
NF
Start
End
15
16
21
1
1
1
-3
-3
-3
-4
-2
0
1
28
28
33
25
23
23
28
15
15
15
15
15
15
108
108
108
108
108
108
108
108
108
108
108
108
108
30dB Gain
Rang
e
80
80
75
83
85
85
80
93
93
93
93
93
93
NF
Start
End
8
9
21
2
2
0
-2
-4
-4
-5
-5
-2
-1
23
23
33
25
25
22
18
15
13
13
13
13
13
98
98
98
98
98
98
98
98
98
98
98
98
98
40dB Gain
Rang
e
75
75
65
73
73
76
80
83
85
85
85
85
85
NF
Start
End
7
8
26
-1
-4
-7
-9
-10
-10
-10
-8
-6
-2
20
20
33
28
22
15
11
8
6
6
8
8
12
88
88
88
88
88
88
88
88
88
88
88
88
88
50dB Gain
Rang
e
68
68
50
60
66
73
77
80
82
82
80
78
76
NF
Start
End
6
8
23
1
-4
-7
-8
-9
-10
-10
-8
-6
-3
20
20
40
23
23
18
8
8
8
8
8
8
13
78
78
78
78
78
78
78
78
78
78
78
78
78
Rang
e
58
58
38
55
55
60
70
70
70
70
70
70
65
*NF is electrical noise floor.
AUD Mode Specifications
AC/DC output:
For AUD, AC and DC
outputs are undefined.
Pulse mode:
The pulse test output is
computed from a
Discrete Hilbert
Transform which is
sampled every ½
millisecond. The
Discrete Hilbert
Transform produces a
mathematically correct
sample of the input
waveform envelope.
Time resolution:
0.5 ms to 1.0 seconds
in 0.5 ms increments
Time accuracy:
±1.0 ms
Hilbert transform
magnitude error:
< 0.1 dB
Dynamic range:
> 80 dB
Hilbert transform
Sample rate:
2000 Hz
824 Reference Manual
2/6/17
On level computation:
After the “ON” state has
been detected, the
“ON” level is computed
as the average of 32
samples.
Overshoot computation:
Overshoot is calculated
as the maximum
sample level minus the
averaged “ON” level
Measurement
conditions:
Conditions that must be
met to produce output:
•
ON/OFF modulation must be
greater than 20 dB (90%).
•
The “ON” state must be stable
within ±0.5dB for at least 20
ms.
•
Pulse transition from high to
low must occur within 2 seconds of the transition from low
to high for the fall time to be
calculated. If this time is
greater than 2 seconds, the
824 will revert to looking for the
pulse rise time.
FM Modulation Tests
The FM modulation test code computes the minimum and
maximum periods of the input waveform. The minimum and
maximum frequencies are the inverse of the average of the
last 8 periods. The carrier frequency is an exponential average of all waveform periods. Signal will be flagged as stable
if the carrier period varies less than 8 microseconds for 1
second.
Carrier frequency (Fc):
20 Hz  fc  16000 Hz
Modulating frequency (fm):
3 Hz  fm  100 Hz
Carrier to modulating frequency ratio:
fc > fm * 5
Signal amplitude:
Overload -35dB Overload
SLM/RTA
The 1/3 octave filters used in the audiometric calibration
firmware are the same filters as are used in the SSA firmware and meet the same specifications, (page D-8).
2/6/17
C -15
400 Line FFT
Averaging:
Count
Window:
Rectangular or Hanning
Linearity range:
>85 dB with Hanning window,
20 kHz bandwidth, and PRM902
Dynamic range:
>100 dB
Flat SPL linearity range:
>75 dB
Highpass frequency vs. filter bandwdth for 824 FFT
Bandwidth
C-16
Hz/Bin
-0.2 dB
20,000
50.00
9.5
10,000
25.00
6.5
5,000
12.50
5.5
2,000
5.00
0.85
1,000
2.50
0.85
500
1.25
0.85
200
0.50
0.85
824 Reference Manual
2/6/17
Typical response of AUD A-weight and C-weight high
pass filters
Frequency Weightings
Nominal
Freq.
2/6/17
Exact
Freq.
Flat
A Weight
C Weight
10
10.00
0.0
-72.6
-14.5
12.5
12.59
0.0
-65.5
-11.4
16
15.85
0.0
-58.8
-8.6
20
19.95
0.0
-52.5
-6.3
25
25.12
0.0
-46.8
-4.5
31.5
31.62
0.0
-41.5
-3.1
40
39.81
0.0
-36.6
-2.1
50
50.12
0.0
-32.2
-1.4
63
63.10
0.0
-28.2
-0.9
80
79.43
0.0
-24.5
-0.6
100
100.00
0.0
-21.1
-0.4
125
125.00
0.0
-18.1
-0.2
160
158.50
0.0
-15.3
-0.1
200
199.50
0.0
-12.8
-0.1
250
251.20
0.0
-10.6
-0.1
315
316.20
0.0
-8.6
0.0
400
398.10
0.0
-6.7
0.0
500
501.20
0.0
-5.2
0.0
630
631.00
0.0
-3.8
0.0
800
794.30
0.0
-2.8
0.0
1000
1000.00
0.0
-1.9
0.0
1250
1259.00
0.0
-1.3
0.0
1600
1585.00
0.0
-0.9
0.0
2000
1995.00
0.0
-0.6
0.0
2500
2512.00
0.0
-0.4
0.0
3150
3162.00
0.0
-0.2
0.0
4000
3981.00
0.0
-0.2
0.0
5000
5012.00
0.0
-0.1
0.0
6300
6310.00
0.0
-0.1
0.0
8000
7943.00
0.0
0.0
0.0
10000
10000.00
0.0
0.0
0.0
12500
12590.00
0.0
0.0
0.0
16000
15850.00
0.0
0.0
0.0
20000
19950.00
0.0
0.0
0.0
C -17
RTA Mode Specifications
Filter types:
Flat, A or C
preweighted 1/3 or 1/1
octave filters with
broadband SPL
Averaging
C-18
Exponential:
1/32, 1/16, 1/8, 1/4, 1/2,
1, 2, 4, 8, 16, 32, 64
seconds
Linear:
0.0025 to 99.995
seconds
Overall time:
> 1 year
Linearity range:
> 80 dB 1/3 octave
>75 dB 1/1 octave
Reference level range:
0 dB gain
Sample rate:
51,200 Hz
1/3 octave band
frequencies:
12.5 Hz - 20 kHz (33
filters)
1/1 octave band
frequencies:
16 Hz - 16 kHz (11
octaves)
Filter integrated
response:
 ±0.15 dB for all filters
Real-time operation:
±0.3 dB error for all
filters tested with a
swept sinusoidal input
Anti-aliasing:
 75 dB
Summation of output
signals:
±1.0 dB (±0.4 typical)
Flat frequency
response:
10 Hz - 20 kHz, relative
attenuation <±0.15 dB
Filter type:
Digital
Octave frequency ratio:
Base 2
824 Reference Manual
2/6/17
AC/DC output:
AC out 1 is flat
weighted and follows
the gain (tip); AC out 2
is C-weighted with 0 dB
gain (ring)
Measurement range:
Flat is measured to
ANSI S1.4 and IEC
60651 standards for
SLM linearity. 1/3 and
1/1 octave filters are
measured to IEC 1260
standard for Class 0
linearity which is ±0.3
dB. The numbers in the
table represent SPL
levels with a typical
377B41 microphone
that has 44.1 mV/Pa
sensitivity.
Measurement Range (RTA mode only)
0dB Gain
FLAT
NF
Start
32
48
10dB Gain
Rang
e
128
80
End
20db Gain
NF
Start
End
25
38
118
Rang
e
80
30dB Gain
NF
Start
21
33
Rang
e
108
75
End
40dB Gain
NF
Start
End
21
33
98
Rang
e
65
50dB Gain
NF
Start
End
26
38
88
Rang
e
50
NF
Start
End
23
40
78
Rang
e
38
1/3 Octave Filters
16.0
2
45
31.5
3
43
63.0
4
40
125
2
40
250
3
37
500
12
33
1000
10
32
2000
15
32
4000
14
32
8000
14
32
16000
15
36
128
128
128
128
128
128
128
128
128
128
128
83
85
88
88
91
95
96
96
96
96
92
2
1
0
-2
-3
4
2
6
7
7
9
35
35
33
27
25
25
20
20
20
20
25
118
118
118
118
118
118
118
118
118
118
118
83
83
85
91
93
93
98
98
98
98
93
1
1
1
-3
-3
-3
-4
-2
0
1
2
25
23
23
28
15
15
15
15
15
15
15
108
108
108
108
108
108
108
108
108
108
108
83
85
85
80
93
93
93
93
93
93
93
2
2
0
-2
-4
-4
-5
-5
-2
-1
1
25
25
22
18
15
13
13
13
13
13
15
98
98
98
98
98
98
98
98
98
98
98
73
73
76
80
83
85
85
85
85
85
83
-1
-4
-7
-9
-10
-10
-10
-8
-6
-2
0
28
22
15
11
8
6
6
8
8
12
15
88
88
88
88
88
88
88
88
88
88
88
60
66
33
77
80
82
82
80
78
76
73
1
-4
-7
-8
-9
-10
-10
-8
-6
-3
1
23
23
18
8
8
8
8
8
8
13
18
78
78
78
78
78
78
78
78
78
78
78
55
55
60
70
70
70
70
70
70
65
60
1/1 Octave Filters
16.0
2
50
31.5
3
48
63.0
4
45
125
2
45
250
3
42
500
12
38
1000
10
37
2000
15
37
4000
14
37
8000
14
37
16000
15
41
128
128
128
128
128
128
128
128
128
128
128
78
80
83
83
86
90
91
91
91
91
87
2
1
0
-2
-3
4
2
6
7
7
9
40
40
48
32
30
30
25
25
25
25
30
118
118
118
118
118
118
118
118
118
118
118
78
78
70
86
88
88
93
93
93
93
88
1
1
1
-3
-3
-3
-4
-2
0
1
2
30
28
28
31
20
20
20
20
20
20
20
108
108
108
108
108
108
108
108
108
108
108
78
80
80
77
88
88
88
88
88
88
88
2
2
0
-2
-4
-4
-5
-5
-2
-1
1
30
30
37
23
20
18
18
18
18
18
20
98
98
98
98
98
98
98
98
98
98
98
68
68
61
75
78
80
80
80
80
80
78
-1
-4
-7
-9
-10
-10
-10
-8
-6
-2
0
33
27
20
26
13
11
11
13
13
17
20
88
88
88
88
88
88
88
88
88
88
88
55
61
68
62
75
77
77
75
78
71
68
1
-4
-7
-8
-9
-10
-10
-8
-6
-3
1
28
28
23
13
13
13
13
13
13
18
23
78
78
78
78
78
78
78
78
78
78
78
50
50
55
65
65
65
65
65
65
60
55
* NF is electrical noise floor
2/6/17
C -19
1/1 and 1/3 Octave Filters
The 1/1 and 1/3 octave filters (SSA and RTA Options)
comply with all requirements of IEC 61260:1995 including
amendment 1 (2001) for Class 1. These digital filters are
sampled at a rate of 51,200 samples per second, with base 2
center frequencies and having real-time performance for all
filters. The 0 dB gain setting is the reference range and the
reference input signal is 1 Volt rms at 1 kHz.
Frequency Range
1/1 Octave Filters: 16 Hz to 16 kHz
1/3 Octave Filters: 12.5 Hz to 20 kHz
Filter Shapes:
Filters are characterized by the shape of their filter skirts and
the shape of the passbands, which must fit within those
specified by the standards. The following figures present
these for the 1/3 octave band centered at 1 kHz. Overlaid
with these curves are the limit curves associated with IEC
61260:1995 Class 1.
1000 Hz Passband
IEC Class 1 Limits
amplitude (dB)
125.00
120.00
115.00
0.8
0.85
0.9
0.95
1
1.05
1.1
1.15
1.2
Relative Frequency
Figure 13-2 Passband of 1kHz 1/3 Octave Filter
C-20
824 Reference Manual
2/6/17
.
130.00
1000 Hz Filter Skirts
IEC Class 1 Limits
120.00
110.00
100.00
amplitude (dB)
90.00
80.00
70.00
60.00
50.00
40.00
30.00
20.00
10.00
0.1
1
10
Relative Frequency
Figure 13-3 Filter Skirts of 1kHz 1/3 Octave Filter
2/6/17
C -21
Ambient Pressure Response of Free-Field Microphones
(Variation over Static Pressure)
Pressure
65 kPa
75 kPa
85 kPa
93 kPa
101 kPa
110kPa
2520
.38 dB
.20 dB
.14 dB
.069 dB
0.000
-.047 dB
2540
.34 dB
.24 dB
.15 dB
.08 dB
0.000
-.075 dB
377B41
.43 dB
.31 dB
.19 dB
.099 dB
0.000
-.10 dB
NOTE: Results in dB referenced to 101
kPa
Position of Instrument and Operator:
When making a measurement, it is recommended that the
observer be positioned as far behind and to the right of the
instrument as possible to minimize interference of the sound
field at the microphone resulting from body reflections.
When using the 824, the meter is held in one hand with the
arm extended away from the body. Better results can be
obtained by using a tripod.
Effect of Windscreen:
The Corrections which should be subtracted from the
measured data when using the Larson Davis Model WS001
3½ inch diameter windscreen with a ½ inch Larson Davis
microphone are as indicated in the following graphs.
C-22
824 Reference Manual
2/6/17
Windscreen Response with Respect to No
Windscreen
2/6/17
C -23
Frequency Response
Random Incidence Microphone Correction
When random incidence correction is turned on in the 824, a
digital filter is added which gives the necessary correction to
provide random incidence response when measuring with a
free-field microphone.
NOTE: Tested with the preamplifier
and microphone attached directly to
the 824.
C-24
The graphs below show the response of the free-field
microphones before and after the random incidence
correction has been added.
824 Reference Manual
2/6/17
Graph 1 - The 824 in normal range with the 2540 free-field
microphone showing the uncorrected random response.
Graph 2 - The 824 in normal range with the 2540 free-field
microphone showing the corrected random response.
2/6/17
C -25
Graph 3 - The 824 in normal range with the 377B41 freefield microphone showing the uncorrected random response.
Graph 4 - The 824 in normal range with the 377B41 freefield microphone showing the corrected random response.
C-26
824 Reference Manual
2/6/17
Graph 5 - The 824 in normal range with the 2551 free-field
electret microphone showing the uncorrected random
response.
Graph 6 - The 824 in normal range with the 2551 free-field
electret microphone showing the corrected random response.
2/6/17
C -27
Graph 7- The 824 in normal range with the 2551 free-field
electret microphone showing random response with the
random corrector.
Microphone Response Tests with 824
The 824 was oriented with the LCD
facing up for these tests.
The following graphs show the effects on the performance
of the 824 caused by the following:
•
Windscreen
•
Instrument Case
•
High Range
NOTE: The graphs below show typical
results.
C-28
824 Reference Manual
2/6/17
Graph 1 - The 824 in normal range with the 2540
microphone
Graph 2 - The 824 in normal range with the 2540
microphone and windscreen
2/6/17
C -29
Graph 3 - The 824 in high range with the 2540 microphone
Graph 4 - The 824 in high range with the 2540 microphone
and windscreen
C-30
824 Reference Manual
2/6/17
Graph 5 - The 824 in normal range with the 377B41
microphone
Graph 6 - The 824 in normal range with the 377B41
microphone and windscreen
2/6/17
C -31
Graph 7 - The 824 in high range with the 377B41
microphone and windscreen
Graph 8 - The 824 in normal range with the 2551 free-field
microphone.
C-32
824 Reference Manual
2/6/17
Graph 9 - The 824 in normal range with the 2551 free-field
microphone and windscreen.
Directional Characteristics of the 824 with the
2540, 377B41 and 2551 free field microphones
Test Setup
•
The 824 was tested in two different configurations as follows:
- 824 oriented with the LCD facing up
- 824 oriented on it’s side
Definitions
2/6/17
•
The XY plane is defined as the 824 oriented with it’s
LCD facing up.
•
The YZ plane is defined as the 824 oriented on it’s side.
C -33
Graph 1 - 824 in the XY plane fitted with the 2540
microphone @ 1 kHz
Graph 2 - 824 in the XY plane fitted with the 2540
microphone @ 2kHz
C-34
824 Reference Manual
2/6/17
Graph 3 - 824 in the XY plane fitted with the 2540
microphone @ 4 kHz
Graph 4 - 824 in the XY plane fitted with the 2540
microphone @ 8 kHz
2/6/17
C -35
Graph 5 - 824 in the XY plane fitted with the 2540
microphone @ 12.5 kHz
Graph 6 - 824 in the YZ plane fitted with the 2540
microphone @ 1 kHz
C-36
824 Reference Manual
2/6/17
Graph 7 - 824 in the YZ plane fitted with the 2540
microphone @ 2 kHz
Graph 8 - 824 in the YZ plane fitted with the 2540
microphone @ 4 kHz
2/6/17
C -37
Graph 9 - 824 in the YZ plane fitted with the 2540
microphone @ 8 kHz
Graph 10 - 824 in the YZ plane fitted with the 2540
microphone @ 12.5 kHz
C-38
824 Reference Manual
2/6/17
Graph 11 - 824 in the XY plane fitted with the
377B41377B41 microphone @ 1 kHz
Graph 12 - 824 in the XY plane fitted with the 377B41
microphone @ 2 kHz
2/6/17
C -39
Graph 13 - 824 in the XY plane fitted with the 377B41
microphone @ 4 kHz
Graph 14 - 824 in the XY plane fitted with the 377B41
microphone @ 8 kHz
C-40
824 Reference Manual
2/6/17
Graph 15 - 824 in the XY plane fitted with the 377B41
microphone @ 12.5 kHz
Graph 16 - 824 in the YZ plane fitted with the 377B41
microphone @ 1 kHz
2/6/17
C -41
Graph 17 - 824 in the YZ plane fitted with the 377B41
microphone @ 2 kHz
Graph 18 - 824 in the YZ plane fitted with the 377B41
microphone @ 4 kHz
C-42
824 Reference Manual
2/6/17
Graph 19 - 824 in the YZ plane fitted with the 2551
microphone @ 8 kHz
Graph 20 - 824 in the YZ plane fitted with the 377B41
microphone @ 12.5 kHz
2/6/17
C -43
Graph 21 - 824 in the XY plane fitted with the 2551
microphone @ 1 kHz
Graph 22 - 824 in the XY plane fitted with the 2551
microphone @ 2 kHz
C-44
824 Reference Manual
2/6/17
Graph 23 - 824 in the XY plane fitted with the 2551
microphone @ 4 kHz
Graph 24 - 824 in the XY plane fitted with the 2551
microphone @ 8 kHz
2/6/17
C -45
Graph 25 - 824 in the XY plane fitted with the 2551
microphone @ 12.5 kHz
Graph 26 - 824 in the YZ plane fitted with the 2551
microphone @ 1 kHz
C-46
824 Reference Manual
2/6/17
Graph 27 - 824 in the YZ plane fitted with the 2551
microphone @ 2 kHz
Graph 28 - 824 in the YZ plane fitted with the 2551
microphone @ 4 kHz
2/6/17
C -47
Graph 29 - 824 in the YZ plane fitted with the 2551
microphone @ 8 kHz
Graph 30 - 824 in the YZ plane fitted with the 2551
microphone @ 12.5 kHz
C-48
824 Reference Manual
2/6/17
Power/Current Draw of 824 Using External Power
Off
Power
Stopped
LOG
LOG
SSA
SSA
Running with
backlight OFF
Running with
backlight ON
Running with
backlight OFF
Running with
backlight ON
Not Charging
0.012
W
0.96 W
1.28 W
1.73 W
1.72 W
2.21 W
Power
N/A
2.25 W
2.53 W
3.05 W
3.00 W
3.50 W
15 V
0.9 mA
65 mA
85 mA
118 mA
116 mA
150 mA
12 V
1.1 mA
80 mA
107 mA
144 mA
143 mA
184 mA
9V
1.3 mA
105 mA
137 mA
191 mA
189 mA
243 mA
15 V
N/A
155 mA
170 mA
204 mA
202 mA
236 mA
12 V
N/A
187 mA
211 mA
254 mA
248 mA
291 mA
9V
N/A
248 mA
278 mA
339 mA
338 mA
402 mA
Current
Charging
Current
Not Charging
Charging
2/6/17
C -49
C-50
824 Reference Manual
2/6/17
APPENDIX
D
Glossary
Allowed Exposure Time (Ti)
This appendix contains technical definitions of key
acoustical and vibration terms commonly used with Larson
Davis instruments. The reader is referred to American
National Standards Institute document S1.1-1994 for
additional definitions. Specific use of the terms defined are
in the main body of the text.
It is the allowed time of exposure to sound of a constant Aweighted sound level given a chosen Criterion Level,
Criterion Duration, and Exchange Rate. The equation for it
is
Tc
Tc
T i = ----------------------------------------- = ----------------------------------------L
– Lc   Q
L
– Lc   q
2 avg
10 avg
where Lc is the Criterion Level, Tc is the Criterion Duration,
Q is the Exchange Rate, K is the Exchange Rate Factor and
Lavg is the Average Sound Level.
Example: If Lc = 90, Tc = 8, Q = 3 and Li = 95 then
8
8
- = 5.656 = 5 hours and 39 minu
= ------------------------------= ------------------------ 95 – 90   10
 95 – 90   3
10
2
This means that if a person is in this area for 5 hours and 39
minutes he will have accumulated a Noise Dose of 100%.
Standard: ANSI S12.19
Average Sound Level (Lavg)
2/6/17
It is the logarithmic average of the sound during a
Measurement Duration (specific time period), using the
chosen Exchange Rate Factor. Exposure to this sound level
over the period would result in the same noise dose and the
D-1
actual (unsteady) sound levels. If the Measurement Duration
is the same as the Criterion Duration, then Lavg=LTWA(LC)
T
L avg
 2

L t  q 
1
= qLog 10  --- 10 p
dt
T

 T


1
where the Measurement Duration (specified time period) is
T=T2-T1 and q is the Exchange Rate Factor. Only sound
levels above the Threshold Level are included in the
integral. Standard: ANSI S12.19
Community Noise Equivalent
Level (CNEL, Lden)
1
L
= 10log  ----den
10
 24
A rating of community noise exposure to all sources of
sound that differentiates between daytime, evening and
nighttime noise exposure. The equation for it is
0700

0000
1900
10
 L + 10   10
i
+

2200
10
L  10
i
0700
+

1900
2400
10
 L + 5   10
i
+

2200
10
 L + 10   10
i



The continuous equivalent sound level is generally
calculated on an hourly basis and is shown in the equation as
L. The levels for the hourly periods from midnight to 7 a.m.
have 10 added to them to represent less tolerance for noise
during sleeping hours. The same occurs from 10 p.m. to
midnight. The levels for the hourly periods between 7 p.m.
and 10 p.m. have 5 added to them to represent a lessened
tolerance for noise during evening activities. They are
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824 Reference Manual
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energy summed and converted to an average noise exposure
rating.
Criterion Duration (Tc)
It is the time required for a constant sound level equal to the
Criterion Level to produce a Noise Dose of 100%. Criterion
Duration is typically 8 hours.
Example: If the Criterion Level = 90 dB and the Criterion
Duration is 8 hours, then a sound level of 90 dB for 8 hours,
will produce a 100% Noise Dose. See Noise Dose. Standard:
ANSI S12.19
Criterion Sound Exposure
(CSE)
The product of the Criterion Duration and the mean square
sound pressure associated with the Criterion Sound Level
when adjusted for the Exchange Rate. It is expressed in
Pascals-squared seconds when the exchange rate is 3 dB.
where q is the Exchange Rate Factor. See Exchange Rate.
CSE = T c 10
Lc  q
Standard: ANSI S1.25
Criterion Sound Level (Lc)
It is the sound level which if continually applied for the
Criterion Duration will produce a Noise Dose of 100%. The
current OSHA Criterion Level is 90 dB.
Standard: ANSI S12.19
Daily Personal Noise Exposure
(LEP,d)
It is the level of a constant sound over the Criterion Duration
that contains the same sound energy as the actual, unsteady
sound over a specific period. The period is generally shorter,
so the sound energy is spread out over the Criterion Duration
period.
Example: If the Criterion Duration = 8 hours and the specific
period is 4 hours and the average level during the 4 hours is
86 dB, then the LEP,d = 83 dB.
Day-Night Average Sound
Level (DNL, Ldn)
A rating of community noise exposure to all sources of sound that differentiates between daytime and
nighttime noise exposure. The equation for it is
2/6/17
D -3
1
L
= 10log  ----den
10
24

0700

1900
10
 L + 10   10
i
+

0000
2200
10
L  10
i
+
0700
1
L
= 10Log  ----dn
10
24


10
1900
0700

2400
 L + 5   10
i
10
0000
+

0700

10
 L + 10   10
i
2200
2200
 L + 10   10
i
+
2400
10
L  10
i
+

2200
10
 L + 10   10
i






The continuous equivalent sound level (See definition) is generally calculated on an hourly basis and
is shown in the equation as L.
The values for the hourly periods from midnight to 7 a.m.
have 10 added to them to represent less tolerance for noise
during sleeping hours. The same occurs from 10 p.m. to
midnight. They are energy summed and converted to an
average noise exposure rating.
Decibel (dB)
D-4
A logarithmic form of any measured physical quantity and
commonly used in the measurement of sound and vibration.
Whenever the word level is used, this logarithmic form is
implied. The decibel provides us with the possibility of
representing a large span of signal levels in a simple manner
as opposed to using the basic unit Pascal for e.g. acoustic
measurements.
824 Reference Manual
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It is not possible to directly add or subtract physical
quantities when expressed in decibel form since the addition
of logarithmic values correspond to multiplication of the
original quantity.
The word level is normally attached to a physical quantity
when expressed in decibels; for example, Lp represents the
sound pressure level.
The difference between the sound pressure for silence versus
loud sounds is a factor of 1,000,000:1 or more, and it is very
unpractical to use these large numbers. Therefore, a measure
that would relate to “the number of zeros” would help, for
example, 100,000 would be equal to 50 and 1000 would be
equal to 30 and so on. This is the basic principal of the dB
measure.
All dB values are unit free and therefore, the dB value is not
the value of the quantity itself, but the ratio of that quantity
to an actual reference quantity used. Thus, for every level in
decibels there must be a well defined reference quantity.
Sound versus vibration uses different references, but the dB
principal is the same. When the quantity equals the reference
quantity the level is zero. To keep dB values above zero, the
reference is generally set to be the lowest value of the
quantity that we can imagine or normally wish to use.
Before explaining the calculation of dB values, it is useful to
remember the following rules of thumb when dB values are
used for sound levels:
- Doubling of the Sound Pressure = 6 dB
- Doubling of the Sound Power = 3 dB
- Doubling of the Perceived Sound Level = (approx) 10 dB
Note: The latter is frequency and level dependent, but the
value “10 dB” is a good rule of thumb, especially around 1
kHz.
Table 1 shows the actual value of a specific item, such as
sound power, for which the sound level is calculated. First,
the sound power value is divided with the reference used and
then the ten-based logarithm is applied. This value is then
2/6/17
D -5
multiplied by 10 to create the decibel value (see equation D1 below).
For every 10 decibels, a unit called Bel is created. The
decibel stands for: deci for “one tenth” and bel for “Bel”
(compare decimeter). The relationship between Bel and
decibel is thus: 1 Bel = 10 decibels. It is not possible to
directly add or subtract decibel values, since addition of
logarithmic values correspond to multiplication of the
original quantity.
(eq. D-1)
Table 1
Power form, squared units
Ration of Value to Reference
1
10
100
200
1,000
10,000
100,000
1000,000
Exponential Form of
Ratio
100
101
102
102.3
103
104
105
106
Level form
10•Exponent
0
10
20
23
30
40
50
60
Each time the sound pressure level increases by 6 dB, the
corresponding sound pressure value is doubled and thus
multiplied by 2. Each time the sound power level increases
by 3 dB, the sound power value is multiplied by 2. Thus, it is
important to notice that a doubling of the sound power is
equal to 3 dB, and a doubling of the sound pressure is equal
to 6 dB, since a doubling of the sound pressure will result in
a quadruple increase of the sound power. The advantage
with using dB is simply that they remain the same even if we
use sound pressure or sound power. Compare this to the use
of voltage and power units in electrical engineering, units
being related by P~V2. In table 2 an illustration is made of
values calculated on sound pressure, non-squared units.
The original definition of decibel was intended for powerlike quantities, such as sound power. If we consider sound
pressure levels instead (usually denoted P in acoustics), the
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824 Reference Manual
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equation will be the same, since the “two” in the squared
units will move from within the bracket and become a 20 log
instead of a 10 log and thus compensate for using linear or
quadratic units. Please note that it is not allowed to use 20
log for squared units, since that expression assumes that we
use linear units, like sound pressure in acoustics or voltage
in electrical engineering. This is illustrated in equation D-1
below:
2
P
P
dB = 10 Log 10 -------2- = 20 Log ----P
0
P0
;p 0 = 20 Pa
Table 2 illustrates how a a tenfold increase of the sound
pressure will result in an increase in 20 dB steps, while
sound power increases in 10 dB steps. See the linear form
(Table 2) and compare with equation D-1. In conclusion, dB
values are always the same, independent of using sound
power or sound pressure as the base unit. A 6 dB increase
implies four times the sound power or two times the sound
pressure.
Table 2
Linear form, non-squared units
Ration of Value to Reference
1
10
100
200
1,000
10,000
100,000
1000,000
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Exponential Form of
Ratio
100
101
102
102.3
103
104
105
106
Level form
20•Exponent
0
20
40
46
60
80
100
120
D -7
Department of Defense Level
(LDOD)
The Average Sound Level calculated in accordance with
Department of Defense Exchange Rate and Threshold Level.
See Average Sound Level
Dose
(See Noise Dose)
Detector
The part of a sound level meter that converts the actual
fluctuating sound or vibration signal from the microphone to
one that indicates its amplitude. It first squares the signal,
then averages it in accordance with the time-weighting
characteristic, and then takes the square root. This results in
an amplitude described as rms (root-mean-square).
Eight Hour Time-Weighted
Average Sound Level (L TWA(8))
It is the constant sound level that would expose a person to
the same Noise Dose as the actual (unsteady) sound levels.
The equation for it is
D
L TWA  8  = L c + qLog 10  ---------
 100
NOTE: This definition applies only for a Criterion Duration
of 8 hours.
Standard: ANSI S12.19
Energy Equivalent Sound Level
(Leq)
The level of a constant sound over a specific time period that
has the same sound energy as the actual (unsteady) sound
over the same period.
T2 2
p  t  dt
T1
L eq = 10Log 10 -------------------------2
po T

where p is the sound pressure and the Measurement
Duration (specific time period) T=T2-T1. See Sound
Exposure Level.
Exchange Rate (Q), Exchange
Rate Factor (q), Exposure
Factor (k)
D-8
It is defined in ANSI S1.25 as “the change in sound level
corresponding to a doubling or halving of the duration of a
sound level while a constant percentage of criterion
exposure is maintained.” The rate and the factors are given
824 Reference Manual
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in the table below.
Standard: ANSI S12.19
Exchange Rate, Q
3.01
4
5
6.02
Far Field
Exchange Rate
Factor, q
10
13.333
16.667
20
Exposure Factor, k
1
.75
.60
.50
There are two types of far fields: the acoustic far field and
the geometric far field.
Acoustic Far Field: The distance from a source of sound is
greater than an acoustic wavelength. In the far field, the
effect of the type of sound source is negligible. Since the
wavelength varies with frequency (See the definition of
Wavelength), the distance will vary with frequency. To be in
the far field for all frequencies measured, the lowest
frequency should be chosen for determining the distance.
For example, if the lowest frequency is 20 Hz, the
wavelength at normal temperatures is near 56 ft. (17 m); at
1000 Hz, the wavelength is near 1.1 ft. (1/3 m). See the
definition of Acoustic Near Field for the advantages of in the
acoustic far field.
Geometric Far Field: The distance from a source of sound is
greater than the largest dimension of the sound source. In the
far field, the effect of source geometry is negligible. Sound
sources often have a variety of specific sources within them,
such as exhaust and intake noise. When in the far field, the
sources have all merged into one, so that measurements
made even further away will be no different. See the
definition of Geometric Near Field for the advantages of
being in the geometric far field.
Free Field
A sound field that is free of reflections. This does not mean
that the sound is all coming from one direction as is often
assumed, since the source of sound may be spatially
extensive. See the definitions of near and far fields for more
detail. This definition is often used in conjunction with
reverberant field.
Frequency (Hz, rad/sec)
The rate at which an oscillating signal completes a complete
cycle by returning to the original value. It can be expressed
2/6/17
D -9
in cycles per second and the value has the unit symbol Hz
(Hertz) added and the letter f is used for a universal
descriptor. It can also be expressed in radians per second,
which has no symbol, and the greek letter  is used for a
universal descriptor. The two expressions are related through
the expression =2f.
Frequency Band Pass Filter
The part of certain sound level meters that divides the
frequency spectrum on the sound or vibration into a part that
is unchanged and a part that is filtered out. It can be
composed of one or more of the following types:
Low Pass: A frequency filter that permits signals to pass
through that have frequencies below a certain fixed
frequency, called a cutoff frequency. It is used to
discriminate against higher frequencies.
High Pass: A frequency filter that permits signals to pass
through that have frequencies above a certain fixed
frequency, called a cutoff frequency. It is used to
discriminate against lower frequencies.
Bandpass: A frequency filter that permits signals to pass
through that have frequencies above a certain fixed
frequency, called a lower cutoff frequency, and below a
certain fixed frequency, called an upper cutoff frequency.
The difference between the two cutoff frequencies is called
the bandwidth. It is used to discriminate against both lower
and higher frequencies so it passes only a band of
frequencies.
Octave band: A bandpass frequency filter that permits
signals to pass through that have a bandwidth based on
octaves. An octave is a doubling of frequency so the upper
cutoff frequency is twice the lower cutoff frequency. This
filter is often further subdivided in 1/3 and 1/12 octaves (3
and 12 bands per octave) for finer frequency resolution.
Instruments with these filters have a sufficient number of
them to cover the usual range of frequencies encountered in
sound and vibration measurements.The frequency chosen to
describe the band is that of the center frequency. Note table
in Frequency Filter - Frequency Weighting.
Frequency Filter - Weighted
D-10
A special frequency filter that adjusts the amplitude of all
parts of the frequency spectrum of the sound or vibration
824 Reference Manual
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unlike band pass filters. It can be composed of one or more
of the following types:
A-Weighting: A filter that adjusts the levels of a frequency
spectrum in the same way the human ear does when exposed
to low levels of sound. This weighting is most often used for
evaluation of environmental sounds. See table below.
B-Weighting: A filter that adjusts the levels of a frequency
spectrum in the same way the human ear does when exposed
to higher levels of sound. This weighting is seldom used.
See table below.
C-Weighting: A filter that adjusts the levels of a frequency
spectrum in the same way the human ear does when exposed
to high levels of sound. This weighting is most often used
for evaluation of equipment sounds. See table below.
Flat-Weighting: A filter that does not adjust the levels of a
frequency spectrum. It is usually an alternative selection for
the frequency-weighting selection.
Center Frequencies, Hz
1/3 Octave
20
25
31.5
40
50
63
80
100
125
160
200
2/6/17
1 Octave
31.5
63
125
Weighting Network Frequency
Response
A
B
C
-50.4
-24.2
-6.2
-44.7
-20.4
-4.4
-39.4
-17.1
-3.0
-34.6
-14.2
-2.0
-30.2
-11.6
-1.3
-26.2
-9.3
-0.8
-22.5
-7.4
-0.5
-19.1
-5.6
-0.3
-16.1
-4.2
-0.2
-13.4
-3.0
-0.1
-10.9
-2.0
0
D -11
Center Frequencies, Hz
1/3 Octave
250
315
400
500
630
800
1000
1250
1600
2000
2500
3150
4000
5000
6300
8000
10000
12500
16000
20000
1 Octave
250
500
1000
2000
4000
8000
16000
Weighting Network Frequency
Response
A
B
C
-8.6
-1.3
0
-6.6
-0.8
0
-4.8
-0.5
0
-3.2
-0.3
0
-1.9
-0.1
0
-0.8
0
0
0
0
0
0.6
0
0
1.0
0
-0.1
1.2
-0.1
-0.2
1.3
-0.2
-0.3
1.2
-0.4
-0.5
1.0
-0.7
-0.8
0.5
-1.2
-1.3
-0.1
-1.9
-2.0
-1.1
-2.9
-3.0
-2.5
-4.3
-4.4
-4.3
-6.1
-6.2
-6.6
-8.4
-8.5
-9.3
-11.1
-11.2
Leq
See “Energy Equivalent Sound Level”, “Sound Level”,
Energy Average”, and “Time Weighted Average”
Level (dB)
A descriptor of a measured physical quantity, typically used
in sound and vibration measurements. It is attached to the
name of the physical quantity to denote that it is a
logarithmic measure of the quantity and not the quantity
itself. The word decibel is often added after the number to
express the same thing. When frequency weighting is used
the annotation is often expressed as dB(A) or dB(B).
Measurement Duration (T)
The time period of measurement. It applies to hearing
damage risk and is generally expressed in hours.
Standard: ANSI S12.19
Microphone Guidelines
Microphone - Types: A device for detecting the presence of
sound. Most often it converts the changing pressure
associated with sound into an electrical voltage that
duplicates the changes. It can be composed of one of the
following types:
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824 Reference Manual
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Capacitor (Condenser): A microphone that uses the motion
of a thin diaphragm caused by the sound to change the
capacitance of an electrical circuit and thereby to create a
signal. For high sensitivity, this device has a voltage applied
across the diaphragm from an internal source.
Electret: A microphone that uses the motion of a thin
diaphragm caused by the sound to change the capacitance of
an electrical circuit and thereby to create a signal. The
voltage across the diaphragm is caused by the charge
embedded in the electret material so no internal source is
needed.
Microphone - Uses: The frequency response of
microphones can be adjusted to be used in specific
applications. Among those used are:
Frontal incidence (Free Field): The microphone has been
adjusted to have an essentially flat frequency response when
in a space relatively free of reflections and when pointed at
the source of the sound.
Random incidence: The microphone has been adjusted to
have an essentially flat frequency response for sound waves
impinging on the microphone from all directions.
Pressure: The microphone has not been adjusted to have an
essentially flat frequency response for sound waves
impinging on the microphone from all directions.
What a microphone measures: A microphone detects more
than just sound. The motion of a microphone diaphragm is
in response to a force acting on it. The force can be caused
by a number of sources only one of which are we interested:
sound. Non-sound forces are: (1) direct physical contact
such as that with a finger or a raindrop; (2) those caused by
the movement of air over the diaphragm such as
environmental wind or blowing; (3) those caused by
vibration of the microphone housing; and (4) those caused
by strong electrostatic fields.
Rules:
1. Do not permit any solid or liquid to touch the microphone
diaphragm. Keep a protective grid over the diaphragm.
2. Do not blow on a microphone and use a wind screen over
the microphone to reduce the effect of wind noise.
3. Mount microphones so their body is not subject to
vibration, particularly in direction at right angles to the plane
of the diaphragm.
2/6/17
D -13
4. Keep microphones away from strong electrical fields.
A microphone measures forces not pressures. We would like
the microphone to measure sound pressure (force per unit
area) instead of sound force. If the pressure is applied
uniformly over the microphone diaphragm a simple constant
(the diaphragm area) relates the two, but if the pressure
varies across the diaphragm the relationship is more
complex. For example, if a negative pressure is applied on
one-half the diaphragm and an equal positive pressure is
applied to the other half, the net force is zero and essentially
no motion of the diaphragm occurs. This occurs at high
frequencies and for specific orientations of the microphone.
Rules:
1. Do not use a microphone at frequencies higher than
specified by the manufacturer; to increase the frequency
response choose smaller microphones.
2. Choose a microphone for free field or random incidence
to minimize the influence of orientation.
A microphone influences the sound being measured. The
microphone measures very small forces, low level sound can
run about one-billionth of a PSI! Every measurement
instrument changes the thing being measured, and for very
small forces that effect can be significant. When sound
impinges directly on a microphone the incident wave must
be reflected since it cannot pass through the microphone.
This results in the extra force required to reflect the sound
and a microphone output that is higher than would exist if
the microphone were not there. This is more important at
high frequencies and when the microphone is facing the
sound source.
Rules:
1. Do not use a microphone at frequencies higher than
specified by the manufacturer; to increase the frequency
response choose smaller microphones.
2. Choose a microphone for free field or random incidence
to minimize the influence of orientation.
A microphone measures what is there from any direction:
Most measurements are intended to measure the sound level
of a specific source, but most microphones are not
directional so they measure whatever is there, regardless of
source.
Rules:
1. When making hand-held measurements, keep your body
at right angles to the direction of the sound you are
interested in and hold the meter as far from your body as
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824 Reference Manual
2/6/17
possible. Use a tripod whenever possible.
2. Measure the influence of other sources by measuring the
background sound level without the source of interest. You
may have to correct for the background.
Near Field
There are two types of near fields: the acoustic near field
and the geometric near field.
Acoustic Near Field: The distance from a source of sound is
less than an acoustic wavelength. In the near field, the effect
of the type of sound source is significant. Since the
wavelength varies with frequency (See the definition of
Wavelength), the distance will vary with frequency. The
most common example of a near field is driving an
automobile with an open window. As you move your ear to
the plane of the window, the sound pressure level builds up
rapidly (wind noise) since most of the pressure changes are
to move the air and very little of it compresses the air to
create sound. Persons not far way, can hardly hear what you
hear. The acoustic near field is characterized by pressures
that do not create sound that can be measured in the far field.
Therefore measurements made here are not useful in
predicting the sound levels far way or the sound power of
the source.
Geometric Near Field: The distance from a source of sound
is less than the largest dimension of the sound source. In the
near field, effect of source geometry is significant. Sound
sources often have a variety of specific sources within them,
such as exhaust and intake noise. When in the near field, the
sound of a weaker, but close, source can be louder than that
of a more distant, but stronger, source. Therefore
measurements made here can be used to separate the various
sources of sound, but are not useful in predicting the sound
levels and sound spectrum far from the source.
Noise
Typically it is unwanted sound. This word adds the response
of humans to the physical phenomenon of sound. The
descriptor should be used only when negative effects on
people are known to occur. Unfortunately, this word is used
also to describe sounds with no tonal content (random):
Ambient: The all encompassing sound at a given location
caused by all sources of sound. It is generally random, but
need not be.
2/6/17
D -15
Background: The all encompassing sound at a given location
caused by all sources of sound, but excluding the source to
be measured. It is essentially the sound that interferes with a
measurement.
Pink: It is a random sound that maintains constant energy
per octave. Pink light is similar to pink noise in that it has a
higher level at the lower frequencies (red end of the
spectrum).
White: It is a random sound that contains equal energy at
each frequency. In this respect, it is similar to white light.
Noise Dose (D)
It is the percentage of time a person is exposed to noise that
is potentially damaging to hearing. Zero represents no
exposure and 100 or more represents complete exposure. It
is calculated by dividing the actual time of exposure by the
allowed time of exposure. The allowed time of exposure is
determined by the Criterion Duration and by the sound level
(the higher the level, the shorter the allowed time). The
sound levels must be measured with A-frequency weighting
and slow exponential time weighting. See Projected Noise
Dose.
100 T  L – L   q
D = ------------ 10 i c
Tc
where
T is Measurement Duration
Tc is Criteria Time
Li is TWA
Lc is Criteria Level
q is exchange rate factor; see page D-8 "Exchange Rate (Q),
Exchange Rate Factor (q), Exposure Factor (k)"
Standard: ANSI S12.19
D-16
824 Reference Manual
2/6/17
Noise Exposure
(See Sound Exposure)
OSHA Level (LOSHA)
The Average Sound Level calculated in accordance with the
Occupational Safety and Health Administration Exchange
Rate and Threshold Level.
Preamplifier
A part of the sound level meter that matches a particular
model of microphone to the meter. It must be chosen in
conjunction with a microphone and a cable that connects
them.
Projected Noise Dose
It is the Noise Dose expected if the current rate of noise
exposure continues for the full Criterion Duration period.
Single Event Noise Exposure
Level (SENEL, LAX)
The total sound energy over a specific period. It is a special
form of the Sound Exposure Level where the time period is
defined as the start and end times of a noise event such as an
aircraft or automobile passby.
Sound
The rapid oscillatory compressional changes in a medium
(solid, liquid or gas) that propagate to distant points. It is
characterized by changes in density, pressure, motion, and
temperature as well as other physical quantities. Not all
rapid changes in the medium are sound (wind noise) since
they do not propagate.
The auditory sensation evoked by the oscillatory changes.
Difference between sound and noise: Sound is the physical
phenomenon associated with acoustic (small) pressure
waves. Use of the word sound provides a neutral description
of some acoustic event. Generally, noise is defined as
unwanted sound. It can also be defined as sound that causes
adverse effects on people such as hearing loss or annoyance.
It can also be defined as the sound made by other people. In
every case, noise involves the judgment of someone and
puts noise in the realm of psychology not physics.
Rules:
1. Use word sound to describe measurements to remove the
emotional overtones associated with the word noise. Some
sound metrics use noise in their name and it is proper to use
the name as it is.
2/6/17
D -17
Sound Exposure (SE)
It is the total sound energy of the actual sound during a
specific time period. It is expressed in Pascals-squared
seconds.
T2
SE =
2
 pA  t  dt
T1
where pA is the sound pressure and T2 - T1 is the
Measurement Duration (specific time period).
When applied to hearing damage potential, the equation is
changed to
T2
SE =
  p  t   dt
k
2
A
T1
where k is the Exposure Factor. See Exchange Rate.
Standard: ANSI S1.25
Sound Exposure Level (SEL,
LET)
The total sound energy in a specific time period. The
equation for it is
T2

2
p  t  dt
T
1
SEL = 10 Log 10 -----------------------2
p0 T
The sound pressure is squared and integrated over a specific
period of time (T2-T1) this is called the sound exposure and
has the units Pascal squared- seconds or Pascal squaredhours. P0 is the reference pressure of 20 µPa and T is the
reference time of 1 second. It is then put into logarithmic
D-18
824 Reference Manual
2/6/17
form. It is important to note that it is not an average since the
reference time is not the same as the integration time.
Sound Pressure
The physical characteristic of sound that can be detected by
microphones. Not all pressure signals detected by a
microphone are sound (e.g., wind noise). It is the amplitude
of the oscillating sound pressure and is measured in Pascals
(Pa), Newtons per square meter, which is a metric equivalent
of pounds per square inch. To measure sound, the oscillating
pressure must be separated from the steady (barometric)
pressure with a detector. The detector takes out the steady
pressure so only the oscillating pressure remains. It then
squares the pressure, takes the time average, and then takes
the square root (this is called rms for root-mean square).
There are several ways this can be done.
Moving Average: The averaging process is continually
accepting new data so it is similar to an exponential moving
average. The equation for it is
t
p rms =
– t –    T
1 2
--- p   e
d
T

ts
The sound pressure is squared and multiplied by a
exponential decay factor so that when the time of integration
is near the current time (t) it is essentially undiminished. For
times older (less) than the current time, the value is
diminished and so becomes less important. The rate at which
older data are made less influential is expressed by the
constant T. The larger is it the slower the decay factor
reduces and the slower the response of the system to rapid
changes. These are standardized into three values called
Time Weighting. See the values below.
2/6/17
D -19
Fixed Average: The averaging process is over a fixed time
period. The equation for it is
T2
p rms =
2
1
----------------------- p  t  dt
 T2 – T1 

T1
The sound pressure is squared and averaged over a fixed
time period. Unlike the moving average, the sound pressures
in all time intervals are equally weighted.
Sound Pressure Level (SPL, Lp)
The logarithmic form of sound pressure. It is also expressed
by attachment of the word decibel to the number. The
logarithm is taken of the ratio of the actual sound pressure to
a reference sound pressure which is 20 MicroPascals ( Pa).
There are various descriptors attached to this level
depending on how the actual sound pressure is processed in
the meter:
Instantaneous: The time varying reading on a meter face on
in a meter output due to changes in the sound pressure. The
reading will depend on the time-weighting applied.
The fundamental relationship between the two is logarithmic
p rms
L p = 20log 10 --------p0
p rms = p 0 10
L p  20
where p0 is the reference sound pressure of 20 µPa. The
square of the sound pressure is a power-like quantity that
can be expressed in the original form of the level definition
2
L p = 10log 10
D-20
824 Reference Manual
p rms
---------2
p0
2
2
p rms = p 0 10
L p  10
2/6/17
Sound Pressure Level can be converted to sound pressure as
follows. If the sound pressure is 1 Pascal, then the sound
pressure level is
1
- = 20log 10  50000  = 20  4.699  = 94.0 dB
L p = 20log 10 --------------------–6
20  10
Calibrators often use a level of 94 dB so they generate a
sound pressure of 1 Pascal.
If the sound pressure level = 76.3 dB, then the sound
pressure is
Pa = 20  10
–6
 10
76.3  20
= 20  10
3.815 – 6
= 20  10
– 2.185
= 20  0.0065  = 0.13
Energy Average (Leq): The value of a steady sound measured
over a fixed time period that has the same sound energy as
the actual time varying sound over the same period. This
descriptor is widely used. It is a fixed average (See Sound
Pressure).
Impulse: The value of an impulsive sound. The reading will
depend on the time-weighting applied.
Unweighted Peak: The peak value of a sound with a meter
that has flat frequency weighting and a peak detector.
Weighted Peak: The peak value of a sound with a meter that
has a frequency weighting other than flat and a peak
detector.
Sound Power(W)
The sound power emitted by a sound source. It is measured
in Watts.
Sound Power Level (PWL, Lw)
The logarithmic form of sound power. It is also expressed by
attachment of the word decibel to the number. The logarithm
is taken of the ratio of the actual sound power to a reference
sound power, which is 1 pico-watt. Sound power level
cannot be measured directly, but can only be deduced
2/6/17
D -21
through measurements of sound intensity or sound pressure
around the source. The equation for it is
W
L w = 10log 10 ------W0
Sound Speed, (c,)
W = W 0 10
L w  10
The speed at which sound waves propagate. It is measured
in meters per second. It should not be confused with sound
or particle velocity which relates to the physical motion of
the medium itself.
c = 20.05 degC + 273
c = 49.03 degF + 460
m  sec
ft  sec
Spectrum (Frequency
Spectrum)
The amplitude of sound or vibration at various frequencies.
It is given by a set of numbers that describe the amplitude at
each frequency or band of frequencies. It is often prefixed
with a descriptor that identifies it such as sound pressure
spectrum. It is generally expressed as a spectrum level.
Threshold Sound Level (Lt)
The A-weighted sound level below which the sound
produces little or no Noise Dose accumulation and may be
disregarded. It is used for hearing damage risk assessment.
Standard: ANSI S1.25
Time Weighted Average Sound
Level (TWA, LTWA(TC))
It is the level of a constant sound over the Criterion
Duration, that would expose a person to the same Noise
Dose as the actual (unsteady) sound over the same period. If
the Exchange Rate is 3 dB then the TWA is equal to the Leq.
where Tc=T2-T1 and K is the Exchange Rate Factor. It is
used for hearing damage risk assessment.
Standard: ANSI S12.19
D-22
824 Reference Manual
2/6/17
T
 2 L t  K 
1
p
L TWA  TC  = Klog 10  --- 10
dt
T

 T


1
Time Weighting
The response speed of the detector in a sound level meter.
There are several speeds used.
Slow: The time constant is 1 second (1000 ms). This is the
slowest and is commonly used in environmental noise
measurements.
Fast: The time constant is 1/8 second (125 ms). This is a less
commonly used weighting but will detect changes in sound
level more rapidly.
Impulse: The time constant is 35ms for the rise and 1.5
seconds (1500 ms) for the decay. The reason for the double
constant is to allow the very short signal to be captured and
displayed.
Vibration
The oscillatory movement of a mechanical system
(generally taken to be solid). It is used as a broad descriptor
of oscillations.
Wavelength (l)
The distance between peaks of a propagating wave with a
well defined frequency. It is related to the frequency through
the following equation
c
 = -f
where c is the sound speed and f is the frequency in Hz. It
has the dimensions of length.
Wavenumber (k)
2/6/17
A number that is related to the wavelength of sound and is
used to compare the size of objects relative to the
D -23
wavelength or the time delay in sound propagation. It is
related to wavelength through the following equation

2
2f
k = ------ = -------- = ---c
c

where  is the wavelength, c is the sound speed, f is the
frequency in Hz, and  is the radian frequency. It has the
dimensions of inverse length.
D-24
824 Reference Manual
2/6/17
APPENDIX
E
Memory Usage
The System 824 has a memory size of 2 MB. This is
generally more than adequate for measurements performed
on a day-by-day basis. However, for applications such as
noise monitoring where measurements are performed and
stored automatically over a period of days or weeks, it is
important to be able to calculate the rate at which memory
will be consumed in order to download data before the
memory capacity is reached. The information in this
Appendix will be useful to accomplish this task. Memory
usage for the LOG and SSA instruments will be presented
separately. An example in the form of a Memory Usage
Worksheet will be included for the LOG instrument.
LOG Memory Usage
Each of the 824's History Functions use space out of a common memory. The amount each record
takes is based on the options selected. The following information is provided to assist in determining
the amount of data that can be stored according to the option desired. The example will be show
assuming that all of the memory is available for one measurement though many measurement files
may be stored at one time.
Exceedance Records (Exceedance History Enabled)]
Table E-1: LOG
2/6/17
Memory Use: Exceedance Records
E-1
Interval Records (Intv History Enabled)
Options — add bytes shown if enabled
Basic Interval Record
Intv Save Ln's=[Yes]
Intv Ln Table
Bytes
34
+18
+384
Enabled by “Store Complete Histogram” setting on “Interval” tab of 824 Utility
Wind/Tach = [Yes]
Table E-2: LOG
+5
Memory Use: Interval Records
Daily Records (Daily History Enabled)
Options — add bytes shown if enabled
Basic Daily Record
Save Daily Ln=[Yes]
Daily Ln Table
Bytes
175
+18
+440
Enabled by “Store Complete Histogram” on “Daily” tab in 824 Utility
W ind/Tach = [Yes]
Table E-3: LOG
+19
Memory Use: Daily Records
Time History Records (Time History Enabled)
Options
Hist Resolution
[1.0dB]
[0.1dB]
[1.0dB]
[0.1dB]
[1.0dB]
[0.1dB]
[1.0dB]
[0.1dB]
Table E-4: LOG
Other Level
[ No]
[ No]
[Peak|UwPk|Max]
[Peak|UwPk|Max]
[Advc]
[Advc]
[Advc], Wind/Tach = [Yes]
[Advc]. Wind/Tach = [Yes]
Bytes per record
1
2
2
4
1 plus number of  (enabled levels)
2 plus 2 times each  (enabled levels)
2
4
Memory Use: Time History Records
Other Histories and Memory Usage
Other Histories and Memory Usage
Run Log History
Calibration Log History
LOG File (Store) with Wind/Tach = [No]
LOG File (Store) with Wind/Tach = [Yes]
Table E-5: LOG
E-2
bytes
20 bytes per record
17 bytes per record
7423 each
7481 each
Memory Use: Other Histories and Memory Usage
824 Reference Manual
2/6/17
Estimating Memory Usage:
The easiest way to estimate the memory usage is to work on a time basis such as one day. Estimate
how many Exceedances will occur in a normal day. Calculate the number of Interval, Time History,
Daily, Run Log and Calibration Check records that will be performed in a day. Based on the options
chosen calculate the number of bytes required for each record type and multiply by the number of
records expected per day, sum these values and this is the number of bytes required per day. Divide
this value into the amount of available memory in the 824 (see Tools | Memory display, generally
about two million) and this is the number of days that can be gathered.
As an example, let's assume a job requires monitoring the noise made by trucks coming and going
from a factory near a residential area. From an initial site survey it is discovered that all trucks are over
65dBA at the boundary of the road and residential property and that there seems to be a truck passing
the site every 3 minutes. The occupants of the residential area want to know how many trucks are
traveling this road and why they are disturbed by more than others. The Exceedance Function will be
used to detect events over 65dBA and there are 20 events per hour expected or 240 per day (20 events/
hour time 12 hours/day) assuming that the plant operations will be reduced during the night. Each
event is expected to last 20 seconds and the Excd T.H rate is 1 sample per second. Statistics based on
hourly intervals and a one minute time history are desired to identify disturbance patterns. The time
history will give the A weight Leq normally and we will also get the A Lmax, C Leq and C Lmax. The
following completed worksheet shows the calculations for this example:
2/6/17
E -3
Line
16
17
18
19
Time History Memory Calculation
Resolution
Other Level
[1.0dB]
[None]
[0.1dB]
[None]
[1.0dB]
[Pk-II|Pk-I |Lmax]
[0.1dB]
[Pk-II|Pk-I |Lmax]
1
2
2
4
20
[1.0dB]
[Advc]
1 plus number of 
21
[0.1dB]
[Advc]
2 plus 2 times each 
22
TOTAL bytes / Hist Record
Select the appropriate number of bytes
from lines 16 to 21 above
23
Hist Records / Day
24 hours divided by Hist Period in hours
Enter Number Calculated
i.e. 24/(60 sec/3600 sec per hour)=1440
24
TOTAL Hist Bytes / Day
Multiply lines 22 & 23 – copy to line 28
Line
(enabled levels)
Memory Use per Day Calculation
from line 5
26
Interval History bytes / day
from line 11
27
Daily History bytes / day
from line 22
28
Time History bytes / day
from line 29
2
Run Log bytes / day
n = number of Run Log records / day
30
Calibration Log bytes / day
31
Setup RAM Registers bytes used
32
TOTAL bytes used / day
33
824's Memory Size 2,000,000
34
TOTAL Run Time in days until out of memory
Calculate
8
A Leq & Max, C
Leq & Max

8
1,440
11,520
Bytes
Exceedance History bytes / day
x 20 =
n x 20 bytes/record
1
n = number of Cal Log records / day
x 17 =
n x 17 bytes/record
0
n = number of registers stored
Table E-6: Example
Calculate
(enabled levels)
25
29
E-4
Bytes per record / Used
x 506 =
n x 506 bytes/record
Sum lines 25 to 31
see TOOLS | Memory
Enter total memory shown
divide line 38 by line 37
18,720
1,368
312
11,520
40
17
0
31,977
2,047,485
64 days
LOG Memory Usage Calculation:
824 Reference Manual
2/6/17
824-LOG Memory Usage Worksheet
1
2
3
Exceedance Memory Estimation
Basic Exceedance Record
Excd Time-Hist n=estimated number of samples (129 bytes max)
Wind/Tach=[Yes]
4
5
TOTAL Bytes / Excd
Anticipated Excd / Day
6
TOTAL Excd Bytes / Day
Line
2/6/17
Bytes
32
21+n
3
Used
Bytes Needed
Add lines 1 thru 2
Enter Number
Multiply lines 4 & 5 – copy to line 30
E -5
7
8
9
10
Interval Memory Calculation
Basic Interval Record
Intv Save Ln's
Intv Save Ln Table
Wind/Tach=[Yes]
11
12
TOTAL Bytes / Intv
Anticipated Intv / Day
Line
13
Bytes
Sum lines 7to 10
TOTAL Intv Bytes / Day
Multiply lines 11& 12– copy to line 31
Bytes
14
15
Daily Save 6 Ln Values
18
16
Daily Save Ln Table
440
17
Wind/Tach=[Yes]
19
18
TOTAL Daily Bytes / Day
Line
19
20
21
22
Bytes per record / Used
1
2
2
4
[Advc]
1 plus number of 
24
[0.1dB]
[Advc]
2 plus 2 times each 
25
26
27
[1.0dB]
[0.1dB]
TOTAL bytes / Hist Record
[Advc]
[Advc]
Wind/Tach=[Yes]
Wind/Tach=[Yes]
Line
30
31
32
33
34
36
Calculate
(enabled levels)
Calculate
(enabled levels)
2
4
Select the appropriate number of bytes
from lines 19to 26above
Hist Records / Day
24 hours divided by Hist Period in hours
Enter Number Calculated
i.e. 24/(60 sec/3600 sec per hour)=1440
TOTAL Hist Bytes / Day
Multiply lines 27& 28– copy to line 33
Bytes
Memory Use per Day Calculation
Exceedance History bytes / day
Interval History bytes / day
Daily History bytes / day
Time History bytes / day
Run Log bytes / day
from line 6
from line 13
from line 18
from line 29
x 20 =
n = number of Run Log records / day
35
Bytes Needed
Sum lines 14to 17– copy to line 32
Time History Memory Calculation
Resolution
Other Level
[1.0dB]
[None]
[0.1dB]
[None]
[1.0dB]
[Pk-II|Pk-I |Lmax]
[0.1dB]
[Pk-II|Pk-I |Lmax]
[1.0dB]
29
n x 20 bytes/record
Calibration Log bytes / day
x 17 =
n = number of Cal Log records / day
n x 17 bytes/record
Setup RAM Registers bytes used
x 506 =
n = number of registers stored
n x 506 bytes/record
37
TOTAL bytes used / day
38
824's Memory Size 2,000,000
39
TOTAL Run Time in days until out of memory
Table E-7: LOG
E-6
Used
175
23
28
Bytes Needed
Enter Number Calculated
Daily History Memory Calculation
Basic Daily Record
Line
Used
34
18
384
5
Sum lines 30 to 36
see TOOLS | Memory
Enter total memory shown
divide line 38 by line 37
Memory Usage Worksheet
824 Reference Manual
2/6/17
824-SSA Memory Usage
Interval Records (Intv History Enabled)
Table E-8: SSA Memory
2/6/17
Usage: Interval Records
E -7
Time History Records (Time History Enabled)
Basic Leq (selected by the Weighting setting)
(option)
Leq
A
(option)
Leq
C
(option)
Leq
Flat
(option)
Peak
A
(option)
Peak
C
(option)
Peak
Flat
(option)
Lmax Slow A
(option)
Lmax Slow C
(option)
Lmax Slow Flat
(option)
Lmax Fast A
(option)
Lmax Fast C
(option)
Lmax Fast Flat
(option)
Lmax Impl
A
(option)
Lmax Impl
C
(option)
Lmax Impl
Flat
(option)
Lmin Slow A
(option)
Lmin Slow C
(option)
Lmin Slow Flat
(option)
Lmin Fast A
(option)
Lmin Fast C
(option)
Lmin Fast Flat
(option)
Lmin Impl
A
(option)
Lmin Impl
C
(option)
Lmin Impl
Flat
(option)
Live
SPL Slow A
(option)
Live
SPL Slow C
(option)
Live
SPL Slow Flat
(option)
Live
SPL Fast A
(option)
Live
SPL Fast C
(option)
Live
SPL Fast Flat
(option)
Live
SPL Impl
A
(option)
Live
SPL Impl
C
(option)
Live
SPL Impl
Flat
Leq Spectrum (option)
Live Spectrum (option)
(option)
Wind / Tach
(option)
Temperature (internal to instrument)
(option)
External Power Voltage
(option)
Battery Voltage
Bytes per record
Resolution [0.1dB]
Resolution [1dB]
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
66
33
66
33
4
2
2
1
2
1
2
1
Table E-9: SSA Memory Usage: Time History Records
E-8
824 Reference Manual
2/6/17
Other Histories and Memory Usage
Run Log History
Calibration Log History
SSA File (Store) with ‘Enable Ln’ = [ No]
SSA File (Store) with ‘Enable Ln’ = [Yes]
Table E-10: SSA Memory
2/6/17
bytes
20 bytes per record
17 bytes per record
2503 each file
7623 each file
Usage: Other Histories and Memory Usage
E -9
E-10
824 Reference Manual
2/6/17
APPENDIX
F
SLM Testing to IEC61672-1
Reference Sound Pressure
Level:
This chapter presents information for testing the sound level
meter function of the System 824 according to IEC61672-1
Section 9.3. These data represent the performance of the
instrument when used with the Larson Davis Model 377B41
microphone.
114 dB
Reference Level Range:
Mode
Microphone Reference Point:
2/6/17
Reference Level Range
ISM
Normal
SSA
0 dB Gain
LOG
Normal
FFT
0 dB Gain
RTA
0 dB Gain
AUD
0 dB Gain
TAL
0 dB Gain
Center of diaphragm of Model 377B41 microphone
F-1
Average Frequency Response
Corrections
0 
Free Field
Frequency, Hz
Response
dB
251.19
316.23
398.11
501.19
630.96
794.33
1000.00
1059.25
1122.02
1188.50
1258,93
1333.52
1412.54
1496.24
1584.89
1678.80
1778.28
1883.65
1995.26
2113.49
2238.72
2371.37
2511.89
2660.73
2818.38
2985.38
3162.28
3349.65
3548.13
3758.37
3981.07
4216.97
4466.84
4731.51
5011.87
5308.84
5623.41
5956.62
6309.57
F-2
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.1
0.1
0.1
0.2
0.2
0.2
0.2
0.2
-0.2
-0.2
-0.3
0.1
0.1
0.3
0.2
0.2
0.1
0.1
-0.1
-0.1
0.1
0.4
0.2
0.0
0.1
0.0
0.4
0.1
0.0
-0.1
0.3
The following table presents the corrections for the average
frequency response of the System 824 using a PRM902
preamplifier and a Model 377B41 free-field microphone,
with and without a windscreen. This data include the effects
of reflections and diffraction.
0
Effect of
Free Field
Windscreen
1
Correctons
dB
dB
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
-0.1
-0.1
-0.1
-0.2
-0.2
-0.2
-0.2
-0.2
0.2
0.2
0.3
-0.1
-0.1
-0.3
-0.2
-0.2
-0.1
-0.1
0.1
0.1
-0.1
-0.4
-0.2
0.0
-0.1
0.0
-0.4
-0.1
0.0
0.1
-0.3
Windscreen on
824,
0 Free Field
dB
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.1
0.0
0.0
0.1
0.1
0.1
0.2
0.1
0.2
0.2
0.2
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.2
0.1
0.0
-0.1
-0.2
-0.2
-0.3
-0.3
-0.2
-0.2
-0.1
-0.1
0.0
824 Reference Manual
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.1
0.1
0.1
0.3
0.3
0.3
0.3
0.3
0.0
0.1
-0.1
0.3
0.4
0.6
0.5
0.5
0.4
0.4
0.1
0.0
0.1
0.3
0.0
-0.2
-0.2
-0.3
0.2
-0.1
-0.1
-0.2
0.3
0 
Free Field
Corrections
with Wind
Screen on 824
dB1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
-0.1
-0.1
-0.1
-0.3
-0.3
-0.3
-0.3
-0.3
0.0
-0.0
0.1
-0.3
-0.4
-0.6
-0.5
-0.5
-0.4
-0.4
-0.1
0.0
-0.1
-0.3
0.0
0.2
0.2
0.3
-0.2
-.1
0.1
0.2
-0.3
Expanded
uncertainty
of
Corrections
@95% dB
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.30
0.30
0.30
0.30
0.30
0.30
0.30
0.30
0.30
0.30
0.30
0.30
0.35
0.35
0.35
0.35
0.35
0.35
0.35
0.35
0.35
2/6/17
0 
Free Field
Frequency, Hz
Response
dB
6683.4
7079.46
7498.94
7943.28
8413.95
8952.51
9440.61
1000.00
10592.54
11220.18
11885.01
12589.25
13335.21
14125.38
14962.36
15848.93
16788.04
17782.79
18836.49
19952.62
1
0.5
-0.1
0.1
0.5
0.2
0.5
0.7
0.7
0.5
0.7
0.7
0.6
0.1
0.3
0.8
1.3
1.2
0.9
0.7
0.5
0
Effect of
Free Field
Windscreen
Correctons1
dB
dB
-0.5
0.1
-0.1
-0.5
-0.2
-0.5
-0.7
-0.7
-0.5
-0.7
-0.7
-0.6
-0.1
-0.3
-0.8
-1.3
-1.2
-0.9
-0.7
-0.5
-0.2
-0.2
-0.3
-0.5
-0.4
-0.3
-0.5
-0.3
-0.6
-0.4
-0.8
-0.6
-0.6
-0.7
-0.8
-1.0
-1.0
-0.8
-0.7
-1.0
Windscreen on
824,
0 Free Field
dB
0.3
-0.3
-0.2
-0.1
-0.2
0.2
0.2
0.5
0.0
0.3
-0.1
0.0
-0.5
-0.4
0.0
0.3
0.2
0.1
0.0
-0.5
0 
Free Field
Corrections
with Wind
Screen on 824
dB1
-0.3
0.3
0.2
0.1
0.2
-0.2
-0.2
-0.5
0.0
-0.3
0.1
0.0
0.5
0.4
0.0
-0.3
-0.2
-0.1
0.0
0.5
Expanded
uncertainty
of
Corrections
@95% dB
0.35
0.35
0.35
0.40
0.40
0.40
0.40
0,45
0,45
0,45
0,45
0.50
0.50
0.50
0.50
0.60
0.60
0.60
0.60
0.75
Add numbers in this column to levels read on the 824 to correct the level at a specific frequency
2/6/17
F -3
Periodic Testing of A-Weighted
Sound Levels
The following table presents adjustment data to be used to determine A-weighted sound levels
equivalent to the response to plane sinusoidal sound waves incident from the reference direction
produced by a calibrated multi-frequency sound calibrator and an electostatic actuator.
0 
Free Field Corrections from
B&K4226 Calibrator1
dB
0 
Free Field Corrections with Wnd
Screen from
B&K4226 Calibrator1
dB
0 
Free Field Corrections from
B&K UA0033
Electrostatic
Actuator1
dB
0 
Free Field Corrections with
Wnd Screen
from B&K4226
Calibrator1
dB
31.62
0.1
0.1
0.0
0.0
0.25
63.10
0.1
0.1
0.0
0.0
0.25
125.89
0.1
0.1
0.0
0.0
0.25
251.19
0.1
0.1
0.0
0.0
0.25
501.19
0.0
0.0
-0.1
-0.1
0.25
1000.00
0.0
0.0
0.0
0.0
0.25
1995.26
-0.2
-0.1
-0.1
0.1
0.30
3981.07
1.3
1.3
1.3
1.3
0.35
7943.28
3.1
3.1
3.6
3.7
0.40
12589.25
6.0
6.0
6.4
6.4
0.50
15848.93
8.2
7.9
7.8
7.5
0.60
Frequency,
Hz
1
Expanded uncertaintly of Corrections @95%
confidence,
dB
Add numbers in this column to levels read on the 824 to correct the level at a specific frequency
F-4
824 Reference Manual
2/6/17
A-Weighted Sound Levels at
Upper and Lower Limits of the
Linear Operating Range
The following table presents the nominal A-weighted sound
levels at the upper and lower limits of the linear operating
ranges for each level range. The starting point for testing the
level linear errors of the reference range is 114 dB.
31.5 Hz
1 kHz
4 kHz
8 kHz
12.5 kHz
Normal
Range
63 dB to 128 dB
19 dB to 128 dB
18 dB to 128 dB
21 dB to 128 dB
26 dB to 128 dB
Low Range
59 dB to 108 dB
18 dB to 108 dB
18 dB to 108 dB
19 dB to 108 dB
22 dB to 108 dB
0 dB Gain
83 dB to 128 dB
43 dB to 128 dB
43 dB to 128 dB
47 dB to 128 dB
49 dB to 128 dB
10 dB Gain
73 dB to 118 dB
33 dB to 118 dB
32 dB to 118 dB
35 dB to 118 dB
39 dB to 118 dB
20 dB Gain
64 dB to 108 dB
24 dB to 108 dB
23 dB to 108 dB
25 dB to 108 dB
29 dB to 108 dB
30 dB Gain
58 dB to 98 dB
19 dB to 98 dB
18 dB to 98 dB
20 dB to 98 dB
23 dB to 98 dB
40 dB Gain
58 dB to 88 dB
18 dB to 88 dB
17 dB to 88 dB
19 dB to 88 dB
22 dB to 88 dB
50 dB Gain
58 dB to 76 dB
18 dB to 78 dB
17 dB to 78 dB
19 dB to 78 dB
22 dB to 78 dB
SLM (ISM)
SLM&RTA
(SSA)
Electrical Signal Input Device:
The electrical design of the input device to insert electrical
signals into the preamplifier is a series 18pF ± 5% capacitor.
The Larson Davis ADP005 is used for this purpose. The
ADP005 can be used for noise floor testing by attaching the
included short on the front of the ADP005.
Inherent Noise:
The inherent Noise on the low range in ISM mode or 50 dB
gain in SSA mode:
Frequency Weighting
2/6/17
1
Total Noise
Electrical Noise
2
A
16
7
C
19
13
Flat
24
21
F -5
1
Combination of electronic and thermal noise of the
microphone at 20C measured in a sealed cavity and
vibration isolated.
2
Electronic noise of the instrument with an ADP005 adaptor
in place of the microphone
Maximum Sound Pressure
Level:
The highest sound pressure level the Larson Davis 824 is
designed to accommodate at the level of overload is 128 dB.
The peak-to-peak voltage at this level is 6.25 Vpp input
through the ADP005.
Power Supply Voltage Range:
The battery power supply voltage range for which the
System 824 conforms to this standard is 2.3 to 4.8 volts.
The System 824 will shut down if the battery is below 2.3
volts when used with alkaline batteries and below 3.3 volts
when used with NiMH batteries.
Display Device
The display device will display all levels over the entire
linear operating range on all ranges.
Stabilization Time Following
Changes of Environmental
Conditions:
The typical time interval needed to stabilize after changes in
environmental conditions is as follows:
Electric Field Strength Above
10 V/m:
•
For a temperature change of 5 C, the time is 30 minutes
•
For a static pressure change of 5 kPa, 15 seconds
•
For a humidity change of 30% (non-condensing), 30
minutes
The Larson Davis model 824 was not tested for field
strengths greater than 10 V/m.
Greatest Radio Frequency
Emission Levels:
NOTE: For the specification of emission
of and susceptibility to, radio frequency
fields, the System 824 is classified as
group X sound level meter.
F-6
The mode of operation of the 824 that produced the greatest
radio frequency emission levels was with the 824 set to ISM
mode and with an EXA010 (10' microphone extension
cable) used to connect the PRM902 to the 824. All ranges
were the same. Radio frequency emission in other modes
824 Reference Manual
2/6/17
(LOG and SSA) are the same. Adding the RS232 cable did
not increase the radio frequencies emission levels.
Effect of Electrostatic
Discharges
The System 824 is not affected by electrostatic discharges.
However, standard ESD precautions should be taken with
the 824's more sensitive Control and Serial Ports.
Greatest Susceptibility to AC
Power and Radio Frequency
Fields:
The mode of operation of the 824 that produced the greatest
susceptibility to A.C power frequency and radio frequency
fields was with the 824 set to ISM mode, RS232 cable
attached and with an EXA010 (10' microphone extension
cable) between the PRM902 and the 824.
2/6/17
F -7
F-8
824 Reference Manual
2/6/17
APPENDIX
G
Miscellaneous Information
This appendix contains additional information about the 824
in the form of questions and answers.
Question #1
How can I delete the Instrument Definitions (ID) in the
Setup menu that are labeled permanent?
Answer
There are ten permanent IDs that come with the 824 that are
the factory default settings for the various instruments in the
824. They are there as a starting point from which to make
your own Setups and cannot be deleted. Modify each one
that you need and then save that ID with your own unique
name.
You may test drive or demo any of
the non-purchased permanent
SETUP options. Up to 20 demos are
available if the instrument is reset
(press RESET > Reset Options >
Purge All Data Files). Data cannot
be stored, downloaded or printed but
may be viewed on the display.
You can, however, separate the permanent IDs from your
own custom IDs with a special ID whose name is all
underscore characters. Your setup menu could look like this:
You can have as many as 50 custom
SETUPs besides the 10 permanent
setups.
1)
2)
3)
4)
5)
6)
7)
8)
9)
10)
11)
12)
13)
14)
15)
16)
p
p
p
p
p
p
p
p
p
p
Slow-A
Fast-C
My
My
5s_Hist
_______
SLM&RTA
SLM
AudTest
demo
ROOMS
FFT
Logging
RT60B
TA-LARM
RT60-A
ISM
ISM
ISM
SSA
SSA
ISM
SSA
ISM
AUD
LOG
RTA
FFT
LOG
RTA
TAL
RTA
Integrating SLM set to Slow A weighted SPL
Integrating SLM set to Fast C weighted SPL
Integrating SLM with my personal preferences
Customized SSA with my personal settings
SSA with time histories set for 5 seconds
(dividing line setup, not used otherwise)
Menu items 1 through 6 are custom IDs. Note that for ID
number 6 underscores were used as a separator to put a
2/6/17
G-1
break in the list between the permanent settings and the user
setting. The list is sorted by what is used most often so if a
permanent ID is used it will be seen above the line. In other
words, the IDs that are used most often float to the top of the
list and those that are not used sink to the bottom.
Hint:
To make the underscore filename easily, do the following:
1. Recall an ISM instrument (or any other ID as desired).
2. Press SETUP and highlight the top line, “Edit Settings”, and press
the TOOLS key.
3. Highlight the top line, “Save ID”, and press the check key.
4. A window pops up labeled “ID Name”.
5. Press the RESET key to clear the old name.
6. Push the right arrow key seven times to get to the last name character.
7. Press the down arrow key about eleven times until the underscore
character is showing.
8. Press the check key.
9. Now recall all of the IDs that you want to be above the separator
line.
Question #2
G-2
What is the power or current drawn by the 824 through the
external power jack?
824 Reference Manual
2/6/17
Here is a sample of external power expectation showing
both wattage and current:
Answer
Off
Power
Stopped
LOG
LOG
SSA
SSA
Running with
backlight OFF
Running with
backlight ON
Running with
backlight OFF
Running with
backlight ON
Not Charging
0.012
W
0.96 W
1.28 W
1.73 W
1.72 W
2.21 W
Power
N/A
2.25 W
2.53 W
3.05 W
3.00 W
3.50 W
15 V
0.9 mA
65 mA
85 mA
118 mA
116 mA
150 mA
12 V
1.1 mA
80 mA
107 mA
144 mA
143 mA
184 mA
9V
1.3 mA
105 mA
137 mA
191 mA
189 mA
243 mA
15 V
N/A
65 mA
85 mA
118 mA
116 mA
150 mA
12 V
N/A
80 mA
107 mA
144 mA
143 mA
184 mA
9V
N/A
105 mA
137 mA
191 mA
189 mA
243 mA
Current
Charging
Current
Not Charging
Charging
NOTE: Current (milliamperes) draw
varies with voltage while the power consumed (watts) is constant.
Question #3
What is the minimum RT-60 that can be measured with the
824 RTA?
Answer
The graph on the next page shows the minimum RT-60 that
can be measured. This is also called the “Residual RT-60”
and is a function of the 1/3 octave filter response times.
2/6/17
G -3
Hz
10
100
0
100
00
100
000
100 00
0
1.0
0.1
0.0
0.0
000
100
Seconds
Residual RT-60
010
Question #4
What does “Start Level” do as found in the SSA and LOG
instruments’ “Ln” settings menu?
Answer
The “Start Level” setting indicates where the histogram
table from which Ln data is calculated begins. The table
only has a range of 128 dB yet the 824 can measure over a
150 dB range when the Gain or Range settings are
considered. The default value for “Start Level” is 15 dB and
provides Ln data and SPL histograms from 15 dB up to
142.9 dB.
“Start Level” is also used with the main weighted Leq in the
Time History. Due to internal data encoding, the range is
limited to 127 dB and uses “Start Level” to determine the
desired measurement range. Since the time history is a data
logging function and the likelihood of changing the Gain or
Range setting is slim, this is sufficient range. The other
Advanced Time-History levels do not have such restrictions.
G-4
824 Reference Manual
2/6/17
Since you can select the main Leq to be A-weighted and also
enable another A-weighted Leq (TWA indication in 824
Utility) the two levels will be identical except when the main
Leq is limited by “Start Level”. When set to 15 dB the
lowest time-history Leq will be 16 dB due to the fact that the
lowest value byte (0) is used as a delimiter in the data
structure.
What is a good value to set “Start Level” to? 15 dB is a good
value for most applications since it is just below the thermal
noise rating of most condenser and pre-polarized
microphones. If you need to measure lower and have a
transducer with a lower noise floor, then reduce the value to
just below or at the noise floor. If you are measuring levels
that may be above 143 dB then you will want to raise “Start
Level” to a higher value (a 1/4” microphone can measure
upward of 160 dB so a “Start Level” of 35 dB will give a
range of 35 dB up to 162.9 dB).
Question #5
How are Leq values calculated in the 824 and how is that
different than traditional non-DSP (Digital Signal Processor)
instruments.
Answer
First let's look at the tradition instrument and then the DSP
instrument.
In mixed analog/digital instruments (such as the LD 870 or
820, or the B&K 2236 or 2238) Leq is calculated by
sampling and integrating the output of a True-RMS detector
circuit that has an exponential time constant (generating a
voltage proportional to SPL with the Slow or Fast response)
with an ADC (Analog to Digital Converter). That sample
rate is many times per second to ensure accurate Leq
readings. If an Leq time-history is taken in this type of
instrument, and the storage rate is fast enough, you will see
that the Leq will not decay any faster than the detector rate
of the SPL it is sampling.
New DSP based sound level meters do not have the analog
detector, but rather detect the SPL and Leq digitally by
sampling at a rate that is double the highest desired
frequency (Nyquist) and then processing the waveform. The
System 824 uses a sample rate of 51,200 samples per
second. The Leq detector and the SPL detectors can be
totally isolated without any additional circuitry (the cost to
2/6/17
G -5
do this with analog circuitry would be very prohibitive). So
what is an Leq? It is the energy average of a signal over a
period of time. Now with separate digital detectors, the Leq
does not have to exhibit the decay of the SPL exponential
detector but can be true to its definition. That means that if
an Leq time-history is taken in this type of instrument, you
will not see any SPL decay effects.
Is this good or bad? It is different more than good or bad, but
there are benefits from that difference.
Good: Many scientists feel that this is good because Leq
time-histories show the true dynamics of the signal without
the residual decay effects of an exponential detector. For
example if you measure a sonic boom with a fast Leq timehistory, it can show the two impulses of the 'N' wave and
possibly even an echo or two. On the other hand, the older
instruments will show one pulse that may take upward of 20
seconds to return to the background level.
Bad(?): If you are comparing data from traditional
instruments it is important to be aware of this phenomenon,
but it is not necessarily bad. If the Leq values being
compared are of long duration (one minute or longer) then
there is little blur caused by the exponential detectors of the
older instruments and the data are very comparable.
Question #6
If I choose to save C-weighted SPLs every two seconds in
the LD824's Time-History, what am I getting?
Answer
You get the instantaneous SPL at the end of the two-second
period.
Question #7
How does this compare with C-weighted Leqs?
Answer
The Leq is the true equivalent level for that two-second
period as if the signal level were constant amplitude.
Detailed Explanation:
So what's the difference between sampled SPL and an Leq
for the same period? It depends on whether you are using
fast or slow SPL and the dynamics of the signal, of course,
but the concept is still the same. It all goes back to your
statistics classes and sampling theories. For an integration to
G-6
824 Reference Manual
2/6/17
be accurate, it must sample the data sufficiently fast enough
so that the errors are minimized for a given data variability.
Thus for fast, the amplitude variability is greater so the
sample rate must be faster.
Inside the 824 we sample fast enough that the integration is
always accurate and gives you the Leq data at the time
period desired, i.e. all the energy received for that Leq
period is contained within the Leq. The old instruments
sampled the SPL detectors and integrated the sample
number, so they had to sample them pretty quickly (32
samples per second for the LD 820 & 870).
You indicated that you are looking at a C weighted (the
frequency weighting doesn't matter) SPL sampled every two
seconds. The worst case error between the Leq and the SPL
is with an Impulse whose onset is immediately after a
sample has been taken. The decay for Slow is about 4dB per
second and fast is 8 times faster at 32dB/s. In two seconds
the next sample will read 8dB below that maximum for Slow
and 64dB below the maximum for Fast. Mind you that this is
worst case. You can plug that sawtooth waveform into a
calculator and do an integration to get the Leq, but you see
that there can be a great difference potentially. For example
if the impulse had a max of 108dB and the sample two
seconds after the max was 100dB the Leq would be 105.6
dB; the SPL would be 5.6dB lower than the Leq would be
for that worst case signal.
In the real world we do not get that type of signal too often.
Lightning might be the closest thing to it. Statistically the
confidence can be determined. The timing of these pulses
will not fall so precisely with the sampling and there are not
such narrow impulses that can form this sawtooth waveform,
so we do not see that much error in reality.
Question #8
What is the difference between the Max and Peak level that
can be stored in the LD824's Time-History? What is the
relationship of SPL, Leq, Max and Peak?
Answer
For further information, see
Appendix D on page D-1 and the
preceding Question.
2/6/17
SPL is the instantaneous Slow, Fast or Impulse sound
pressure level as defined by in the ANSI S1.4 and IEC 651
standards. They are true-RMS (root-mean-squared) levels.
G -7
The "detector time constant" for Slow is one second and for
Fast it is one-eighth of a second. The "detector time
constant" for the Impulse detector is 35ms with a fixed
decay time of about 3dB per second.
The Leq is the energy average of the waveform encountered
during the duration of the time-history period.
The Max level is the maximum SPL obtained for the
selected detector during the duration of the time-history
period.
The Peak is the instantaneous maximum amplitude of the
incoming waveform encountered during the duration of the
time-history period. The peak of a continuous sine wave is
3dB higher than its RMS or SPL value.
Question #9
Is it possible to control the 824 'Run' and 'Stop' from an
external signal (example 0 to 5 volt)?
Answer
Yes. The Logic Input line on the control connector at the
base of the 824 can be set to control the Run/Stop of the
instrument. This input takes a zero to five volt digital signal
and performs the function selected by the Logic-In setting
found in the Controls menu (SETUP > Edit Settings >
Controls > Logic-In).
When set to Toggle it works just like the Run/Stop key. You
can connect a momentary push-button switch from the five
volt wind direction power (pin 6) to the logic input control
line (pin 3).
When set to Level it forces the unit to be in run mode when
the logic input is high (+5 Volts) and forces a stop when it is
low (0 Volts). You can connect a toggle switch from the
wind direction power (pin 6) to the Logic Input (pin 3) the
824 will run when the switch is ON and be stopped when the
switch is off. Note: The Level setting will override the Run/
Stop key on the instrument and the M3 & M4 I/O
commands!!!
The 9-PIN Miniature DIN connector needed can be
purchased at www.digikey.com as P/N CP-2090-ND.
Question #10
G-8
What is the key sequence to perform a User Reset?
824 Reference Manual
2/6/17
Answer
2/6/17
By holding down the RESET, the CHECK and the POWER
keys simultaneously to turn the 824 on will activate a User
Reset. This User Reset will perform a complete memory
test, reset all data, erase all user setup IDs (Instrument
Definition or setup file) and recall from EEPROM one SSA,
one LOG and one ISM setup ID. These three setup ID are
created from the Tools > Memory > Create EEPROM
Backup menu item. You may want to perform a User Reset
if the settings stored in the memory of the 824 have become
corrupted. A User Reset is performed whenever the
firmware is upgraded. It advisable to make archive copies of
all setup IDs using 824 Utility software regularly.
G -9
G-10
824 Reference Manual
2/6/17
See Keys
’Control keys ................................................................................................................................. 3-2
Numerics
824
Components ............................................................................................................................ 1-8
Features ................................................................................................................................... 1-5
Optional equipment ................................................................................................................ 1-14
System Diagram ..................................................................................................................... 1-11
Terminal assembly .................................................................................................................. 1-18
824 Utility
Adding Notes to Download File ............................................................................................. 10-21
Additional Features ................................................................................................................ 10-32
Changing download file name ................................................................................................ 10-20
Connecting to a PC ................................................................................................................. 10-2
Creating a New Setup ............................................................................................................. 10-14
Deleting a Setup ..................................................................................................................... 10-16
Downloading Measurement Data ........................................................................................... 10-17
Downloading selected measurements ..................................................................................... 10-22
export data .............................................................................................................................. 10-32
File Extensions ....................................................................................................................... 10-24
Histograms .............................................................................................................................. 10-32
Installation .............................................................................................................................. 10-1
Locking and Unlocking Setups .............................................................................................. 10-17
Modifying Setups ................................................................................................................... 10-9
Opening Setup Disk Files ....................................................................................................... 10-12
Printing a Translated File ....................................................................................................... 10-29
Retrieving setups from 824 .................................................................................................... 10-7
RT60 Select Options ............................................................................................................... 10-33
Saving Setups to Disk Files .................................................................................................... 10-12
Selecting a Data set to view .................................................................................................... 10-27
Selecting Active Measurements ............................................................................................. 10-21
Setup Window ........................................................................................................................ 10-6
Specifying a Destination File ................................................................................................. 10-18
Spreadsheet Program .............................................................................................................. 10-31
Starting ................................................................................................................................... 10-2
Storing Setups ......................................................................................................................... 10-9
Tool Bar .................................................................................................................................. 10-4
Translating Downloaded Files ................................................................................................ 10-25
Viewing Translated File ......................................................................................................... 10-31
824 Utility Software. See 824 Utility
A
About
824 .......................................................................................................................................... 3-20
824 display .............................................................................................................................. 3-20
this manual .............................................................................................................................. 1-1
AC Power ....................................................................................................................................... 3-8
AC power adaptor .......................................................................................................................... 1-17
AC Susceptibility ........................................................................................................................... F-7
Above 10 V/m ........................................................................................................................ F-6
AC/DC Output
connector ................................................................................................................................ 6-5
control settings ........................................................................................................................ 7-12
Filter ....................................................................................................................................... 6-6
Accessories/Optional Equipment ................................................................................................... 1-14
Active ID ....................................................................................................................................... 411 to ................................................................................................................................. 4-12
Advanced Time History
marker text .............................................................................................................................. 7-35
Allocated ID’s ................................................................................................................................ 3-28
Any Data
Check Menu ............................................................................................................................ 7-69
definition ................................................................................................................................. 2-3,
9-5
Read Commands ..................................................................................................................... A-21
Any Impulse
format ..................................................................................................................................... 5-8
Any Time
View ....................................................................................................................................... 5-8
Arrow Keys .................................................................................................................................... 3-11
AUD ............................................................................................................................................... 13-1
Any Level Displays ................................................................................................................ 13-8
Display Sequence ................................................................................................................... 13-5
FFT Display ............................................................................................................................ 13-24
FFT Submenu ......................................................................................................................... 13-5
Flatness FFT Display .............................................................................................................. 13-17
Linearity FFT Display ............................................................................................................ 13-13
Linearity RTA Display ........................................................................................................... 13-9
Microphone Sensitivity Calibration ....................................................................................... 13-4
Modes ..................................................................................................................................... 13-4
Pulse/FM Display ................................................................................................................... 13-20
Pulse/FM Submenu ................................................................................................................ 13-5
Selecting Mode ....................................................................................................................... 13-3
SLM/RTA Submenu ............................................................................................................... 13-5
SLM+RTA Live Display ........................................................................................................ 13-6
THD Display .......................................................................................................................... 13-18
View Menu ............................................................................................................................. 13-5
Audiometer Testing ....................................................................................................................... 13-1
Autostore
ByTime Graph ........................................................................................................................ 11-26
ByTime Spectral History ........................................................................................................ 11-26
ByTime Spectrum ................................................................................................................... 11-26
Leq .......................................................................................................................................... 11-23
Views ...................................................................................................................................... 11-22
B
Back Erase ..................................................................................................................................... 3-10
Back erase function ........................................................................................................................ 2-8
Backlight Time .............................................................................................................................. 3-5
Backup
EEPROM ................................................................................................................................ 3-19
Battery
Compartment .......................................................................................................................... 1-18
Cover ...................................................................................................................................... 1-18
Operating time ........................................................................................................................ C-5
Pack ........................................................................................................................................ 1-16
Terminal Assembly ................................................................................................................ 1-18
Baud Rate ....................................................................................................................................... 3-34
Block Timer ................................................................................................................................... 3-25
Bookmarks ..................................................................................................................................... 1-1
ByTime .......................................................................................................................................... 11-8
C
Cables
Interface .................................................................................................................................. A-1
Microphone extension ............................................................................................................ C-7
Calibration ..................................................................................................................................... 2-14
Change .................................................................................................................................... 4-3
Display .................................................................................................................................... 3-23
High Range ............................................................................................................................. 4-4
History Variables .................................................................................................................... A-58
noise floor ............................................................................................................................... 3-23
Temp/Pressure Compensation ................................................................................................ 2-17
Calibrator
CAL200 .................................................................................................................................. 1-15
CAL250 .................................................................................................................................. 1-15
Recommended ........................................................................................................................ 9-3
Changing
amplitude range ...................................................................................................................... 2-10
detector ................................................................................................................................... 2-8
frequency weighting ............................................................................................................... 2-9
IDs .......................................................................................................................................... 4-11
Instrument Definitions ............................................................................................................ 3-29
secondary parameter ............................................................................................................... 2-10
Settings Menu ......................................................................................................................... 4-17
Check Key ..................................................................................................................................... 3-11
Check Menu ................................................................................................................................... 7-57
Any Data ................................................................................................................................. 7-63
Control Settings ...................................................................................................................... 7-62
example ................................................................................................................................... 7-58
Exceedance History ................................................................................................................ 7-73
Exposure ................................................................................................................................. 7-70
Graph Menu ............................................................................................................................ 7-61
Intervals .................................................................................................................................. 7-64,
7-73
Ln Centiles .............................................................................................................................. 7-67,
7-71
LOG Any Data ....................................................................................................................... 7-69
Mark Display .......................................................................................................................... 7-60
Other Logging Check Menus ................................................................................................. 7-69
Other SSA Check Menus ........................................................................................................ 7-63
RTA ........................................................................................................................................ 7-63
Run Log .................................................................................................................................. 7-66,
7-72
Settings ................................................................................................................................... 7-62
SLM Current/Overall .............................................................................................................. 7-70
SLM Options .......................................................................................................................... 7-60
Stats ........................................................................................................................................ 7-71
Time History ........................................................................................................................... 7-65,
7-72
Clock/Timer ................................................................................................................................... 3-23
CNEL ............................................................................................................................................. 5-59
comma separated variables ............................................................................................................ 10-31
Communication .............................................................................................................................. 3-33
Connecting
PC cable .................................................................................................................................. A-2
to a serial printer ..................................................................................................................... 8-1
Connector
AC/DC Output connector ....................................................................................................... 1-11
Control Connector .................................................................................................................. 1-9
Serial Connector ..................................................................................................................... 1-10
Control
connector ................................................................................................................................ 1-9
keys ......................................................................................................................................... 3-2
Control Settings
AC/DC out .............................................................................................................................. 7-12
Check Menu ............................................................................................................................ 7-62
common .................................................................................................................................. 7-10
E.A. cal tone ........................................................................................................................... 7-16
heater on ................................................................................................................................. 7-16
ISM ......................................................................................................................................... 7-10
Logic input .............................................................................................................................. 7-12
Logic Output ........................................................................................................................... 7-13
Logic Output #2 ...................................................................................................................... 7-16
Logic Output #2.time .............................................................................................................. 7-16
Logic Output time ................................................................................................................... 7-15
SSA, LOG ............................................................................................................................... 7-10
Criterion ......................................................................................................................................... D-3
sound level .............................................................................................................................. D-3
time ......................................................................................................................................... 7-19
Current
Criterion .................................................................................................................................. 7-20
Exchange ................................................................................................................................ 7-19
SLM Views ............................................................................................................................. 5-25
Threshold ................................................................................................................................ 7-19
Cursors (Arrow Keys) .................................................................................................................... 3-2
Customizing
printing ................................................................................................................................... 3-38
SSA settings ............................................................................................................................ 7-2
D
Daily
Enable ..................................................................................................................................... 7-41
History Check Menu ............................................................................................................... 7-74
History Variables .................................................................................................................... A-56
Ln’s ......................................................................................................................................... 7-42
Views ...................................................................................................................................... 5-57
Daisy Chain Addressing ................................................................................................................ A-3
Data
Files ........................................................................................................................................ 3-12
Key ......................................................................................................................................... 3-12
Report ..................................................................................................................................... 7-43
Storage .................................................................................................................................... 2-13
Data Files ....................................................................................................................................... 10-21
Date Format ................................................................................................................................... 3-21
Day-Night Level (Ldn) .................................................................................................................. 5-59
Decibel ........................................................................................................................................... D-4
Deleting
IDs .......................................................................................................................................... 3-17
individual records ................................................................................................................... 3-31
last record ............................................................................................................................... 3-28
last stored record ..................................................................................................................... 3-29
stored data ............................................................................................................................... 3-29
Demonstration Mode
Unenabled IDs ........................................................................................................................ 2-6
Department of Defense
level ........................................................................................................................................ D-8
Detector .......................................................................................................................................... D-8
Diagram
System .................................................................................................................................... 1-13
Display
Indicators ................................................................................................................................ 5-1
Preview ................................................................................................................................... 3-10
Status Icons ............................................................................................................................. 5-1
Display Device
Integrating Measurement ........................................................................................................ 9-12
Levels/Ranges ......................................................................................................................... F-6
Displays
SSA ......................................................................................................................................... 5-11
SSA display+spectra ............................................................................................................... 5-11
SSA Intervals .......................................................................................................................... 5-13
SSA tabular+spectra ............................................................................................................... 5-11
SSA Time History .................................................................................................................. 5-15
Time History Displays ............................................................................................................ 5-12
Displays Logging SLM
Current/Overall-b SLM Displays ........................................................................................... 5-27
Current/Overall-c SLM Displays ........................................................................................... 5-28
Current/Overall-e SLM Displays ........................................................................................... 5-30
Exposure-b Display ................................................................................................................ 5-33
Exposure-c Display ................................................................................................................ 5-34
Ln-a Display ........................................................................................................................... 5-35
Ln-b Display ........................................................................................................................... 5-36
Stats-b Display ........................................................................................................................ 5-38
Stats-c Display ........................................................................................................................ 5-39
Duration
measurement ........................................................................................................................... D-12
E
E.A. Cal Tone ................................................................................................................................ 7-16
EEPROM Backup .......................................................................................................................... 3-19
Eight Hour TWA ........................................................................................................................... D-8
Electrical Input ............................................................................................................................... F-5
Electrostatic Discharges
Effect on 824 .......................................................................................................................... F-7
Entering Settings ............................................................................................................................ A-27
Exceedance
general .................................................................................................................................... 6-8
History Check Menu ............................................................................................................... 7-73
History Display ....................................................................................................................... 5-51
History settings ....................................................................................................................... 7-39
Time History Display ............................................................................................................. 5-55
Exceedance History
Enable ..................................................................................................................................... 7-40
Exceedance Time .................................................................................................................... 7-41
Minimum Duration ................................................................................................................. 7-40
Time History ........................................................................................................................... 7-40
Time History Period ............................................................................................................... 7-40
Timed Excd Period ................................................................................................................. 7-41
Triggering ............................................................................................................................... 7-39
Exchange Rate
glossary ................................................................................................................................... D-8
Exchange Rate Factor
glossary ................................................................................................................................... D-8
Exposure
Check Menu ............................................................................................................................ 7-70
Views ...................................................................................................................................... 5-31
Exposure Factor
glossary ................................................................................................................................... D-8
External Power ............................................................................................................................... 1-16
External Power Source .................................................................................................................. 1-18
F
Fall time ......................................................................................................................................... 13-21
Far Field ......................................................................................................................................... D-9
acoustic ................................................................................................................................... D-9
geometric ................................................................................................................................ D-9
Features .......................................................................................................................................... 1-5
FFT
Bandwidth ............................................................................................................................... 12-3
Calibration .............................................................................................................................. 12-12
Changing dB Reference .......................................................................................................... 12-12
Check Menu ............................................................................................................................ 12-8
Count Averaging .................................................................................................................... 12-4
dB reference level ................................................................................................................... 12-16
Display .................................................................................................................................... 12-6
Display in Linear Units .......................................................................................................... 12-13
FAQs ....................................................................................................................................... 12-16
Features ................................................................................................................................... 12-1
Gain Settings .......................................................................................................................... 12-3
Getting linear units in DNA ................................................................................................... 12-17
Linear Units Display ............................................................................................................... 12-13
Overload Skip ......................................................................................................................... 12-4
Repeat measurements ............................................................................................................. 12-4
Settings Descriptions .............................................................................................................. 12-3
Settings Menu ......................................................................................................................... 12-1
Snapshot Check Menu ............................................................................................................ 12-11
Snapshot Data Storage ............................................................................................................ 12-10
Snapshot, Automatic ............................................................................................................... 12-6
THD Measurement ................................................................................................................. 12-8
Time Domain Windows ......................................................................................................... 12-4
Zoom ....................................................................................................................................... 12-7
Filters
1/1, 1/3 Octave Filter Shapes .................................................................................................. C-20
Fractional Octave Bandwidth ................................................................................................. 7-10
Fractional Octave Detector ..................................................................................................... 7-9
Fractional Octave Display ...................................................................................................... 5-11
Fractional Octave Fast Autostore ........................................................................................... 11-1
Fractional Octave Weighting .................................................................................................. 7-9
Fractional Octave, general ...................................................................................................... 6-3
Formatting Conventions ................................................................................................................ 1-4
Free field ........................................................................................................................................ D-9
Frequency
band pass filter ........................................................................................................................ D-10
glossary ................................................................................................................................... D-9
Hz, rad/sec .............................................................................................................................. D-10
Frequency Response
Average Corrections ............................................................................................................... F-2
Frequency Response Specifications .............................................................................................. C-24
Frequency Spectrum ...................................................................................................................... D-22
G
Getting Started ............................................................................................................................... 1-12
Graph Menu ................................................................................................................................... 7-61
H
Heater
Control .................................................................................................................................... 7-16
High Range
calibration ............................................................................................................................... 4-4
linearity range ......................................................................................................................... 2-4
Histogram
reports ..................................................................................................................................... A-38
Start Level .............................................................................................................................. G-4
History
Advanced Time History ......................................................................................................... 7-34
Daily History .......................................................................................................................... A-56
Enable ..................................................................................................................................... 7-32
Exceedance History ................................................................................................................ A-49
History Data Variables ........................................................................................................... A-49
Interval History ....................................................................................................................... A-51
Marker Text ............................................................................................................................ 7-35
Other Level ............................................................................................................................. 7-33
Period ...................................................................................................................................... 7-32
Period Units ............................................................................................................................ 7-32
Resolution ............................................................................................................................... 7-34
I
ID Name ......................................................................................................................................... 3-16
ID Setting Files
Advanced Menu Layout ......................................................................................................... 7-54
Bandwidth Setting .................................................................................................................. 7-10
Common SLM Settings .......................................................................................................... 7-5
Customizing ............................................................................................................................ 7-2
customizing example .............................................................................................................. 7-2
Customizing Settings .............................................................................................................. 7-2
Detector Settings .................................................................................................................... 7-5
Gain Setting ............................................................................................................................ 7-6
ISM Menu Layout .................................................................................................................. 7-48
LOG and SSA Intervals .......................................................................................................... 7-35
LOG and SSA Ln ................................................................................................................... 7-20
LOG and SSA Time History .................................................................................................. 7-30
Logging SLM Define Report .................................................................................................. 7-42
Logging SLM Exceedance ..................................................................................................... 7-39
Logging SLM Menu Layout ................................................................................................... 7-50
Logging SLM TWA ............................................................................................................... 7-16
Peak Weighting ...................................................................................................................... 7-9
Random Incidence Microphone ............................................................................................. 7-8
Range Setting .......................................................................................................................... 7-7
Recalling ................................................................................................................................. 7-1
RTA Detector ......................................................................................................................... 7-9
RTA Weighting ...................................................................................................................... 7-9
Separating permanent from custom ........................................................................................ G-1
Settings Descriptions .............................................................................................................. 7-4
SSA Menu Layout .................................................................................................................. 7-45
Tilde Symbol .......................................................................................................................... 4-13
Title Setting ............................................................................................................................ 7-5
Transducer Setting .................................................................................................................. 7-8
Weighting Setting ................................................................................................................... 7-6
IEC61672-1
Testing to ................................................................................................................................ F-1
Input
Electrical ................................................................................................................................. F-5
Instrument Definitions
Delete ...................................................................................................................................... 2-2
FFT ......................................................................................................................................... 12-1
Logging (LOG) ....................................................................................................................... 2-4
Name ....................................................................................................................................... 3-16
Rooms (RTA) ......................................................................................................................... 11-1
RT60-A/B (RTA) ................................................................................................................... 11-15
SLM (ISM) ............................................................................................................................. 2-4
SLM&RTA (SSA) .................................................................................................................. 2-2
Types ...................................................................................................................................... 2-2
Write Enable ........................................................................................................................... 2-2
Write Protect ........................................................................................................................... 2-2
Integrated Level Calculations ........................................................................................................ B-1
Interface Cables ............................................................................................................................. A-1
Interval
Auto Stop ................................................................................................................................ 7-38
Check Menu ............................................................................................................................ 7-73
displays ................................................................................................................................... 5-44
Enable ..................................................................................................................................... 7-36
Exchange ................................................................................................................................ 7-38
History .................................................................................................................................... 6-7
Period ...................................................................................................................................... 7-37
save Ln’s ................................................................................................................................. 7-37
Spectral Lns ............................................................................................................................ 5-14
spectrum ................................................................................................................................. 7-39
Threshold ................................................................................................................................ 7-38
time sync ................................................................................................................................. 7-37
ISM Measuring Ranges ................................................................................................................. 6-9
K
Key
Arrow Keys ............................................................................................................................ 3-11
Check Key .............................................................................................................................. 3-11
Data Key ................................................................................................................................. 3-12
navigation ............................................................................................................................... 3-2
Pause Key ............................................................................................................................... 3-10
Power Key .............................................................................................................................. 3-3
Print Key ................................................................................................................................. 3-37
Reset Key ................................................................................................................................ 3-9
Run|Stop Key .......................................................................................................................... 3-8
Setup Key ............................................................................................................................... 3-14
Tools Key ............................................................................................................................... 3-18
View Key ................................................................................................................................ 3-12
Keypad ........................................................................................................................................... 3-1
L
Leq
DSP instrurments vs analog .................................................................................................... G-5
glossary ................................................................................................................................... D-8
Leq vs sampled SPL ............................................................................................................... G-5
Level .............................................................................................................................................. D-12
Dept of Defense ...................................................................................................................... D-8
Linear Range
A-Weight Limits ..................................................................................................................... F-5
Links
Manual (pdf) ........................................................................................................................... 1-3
Ln
Spectral ................................................................................................................................... 5-20
Ln Centiles ..................................................................................................................................... 5-19
Check Menu ............................................................................................................................ 7-71
Views ...................................................................................................................................... 5-35
Ln Settings
Defining Ln’s .......................................................................................................................... 7-21
Enable ..................................................................................................................................... 7-21
Spectral Ln’s ........................................................................................................................... 7-22
LOG ............................................................................................................................................... 7-25,
7-30, ................................................................................................................................. 7-35
LOG ID .......................................................................................................................................... 2-4
LOG Measuring Ranges ................................................................................................................ 6-9
LOG Settings ................................................................................................................................. 7-50
Logging .......................................................................................................................................... 7-42
Logic Input
setting ..................................................................................................................................... 7-12
Logic Output
setting ..................................................................................................................................... 7-13
Logic Output #2
setting ..................................................................................................................................... 7-16
Logic Output #2 Time
setting ..................................................................................................................................... 7-16
Logic Output Time
setting ..................................................................................................................................... 7-15
M
Manual
Bookmarks .............................................................................................................................. 1-1
Links (pdf) .............................................................................................................................. 1-3
Special Features (pdf) ............................................................................................................. 1-1
Mark Display ................................................................................................................................. 7-60
Measuring Ranges
ISM ......................................................................................................................................... 6-9
LOG ........................................................................................................................................ 6-9
SSA ......................................................................................................................................... 6-4
Memory .......................................................................................................................................... 3-27
display ..................................................................................................................................... 3-27
low free memory icon ............................................................................................................. 5-3
structure .................................................................................................................................. 3-29
usage ....................................................................................................................................... E-1
Menu Scrolling .............................................................................................................................. 4-11,
4-13
Metrics Display .............................................................................................................................. 5-65,
5-68
Microphone
guidelines ................................................................................................................................ D-12
what it measures ..................................................................................................................... D-13
Microphones
capacitor ................................................................................................................................. D-13
Conforming ............................................................................................................................. C-1
electret .................................................................................................................................... D-13
uses ......................................................................................................................................... D-13
Modem
answering procedure ............................................................................................................... A-68
Control Mode .......................................................................................................................... A-66
Dial Out Mode ........................................................................................................................ A-66
dialing procedure .................................................................................................................... A-67
initialization ............................................................................................................................ 3-36
mode control ........................................................................................................................... 3-35
monitor numbers ..................................................................................................................... A-67
N
Near Field
acoustic ................................................................................................................................... D-15
geometric ................................................................................................................................ D-15
glossary ................................................................................................................................... D-15
Noise
ambient ................................................................................................................................... D-15
Background ............................................................................................................................. D-15
compensate ............................................................................................................................. A-43
daily personal exposure .......................................................................................................... D-3
dose(D) ................................................................................................................................... D-16
exposure .................................................................................................................................. D-17
floor ........................................................................................................................................ A-43
floor input ............................................................................................................................... 3-23
glossary ................................................................................................................................... D-2,
D-15
Inherent ................................................................................................................................... F-5
pink ......................................................................................................................................... D-16
projected noise dose ............................................................................................................... D-17
single event exposure level ..................................................................................................... D-17
white ....................................................................................................................................... D-16
Note
adding to downloaded file ...................................................................................................... 10-21
O
Off time .......................................................................................................................................... 13-22
On time .......................................................................................................................................... 13-22
OSHA
level ........................................................................................................................................ D-17
Other .............................................................................................................................................. 7-69
Other Level
Views ...................................................................................................................................... 5-43
Overall
Criterion .................................................................................................................................. 7-18
Criterion Level setting ............................................................................................................ 7-18
Exchange ................................................................................................................................ 7-17
SLM Views ............................................................................................................................. 5-25
Threshold ................................................................................................................................ 7-18
overshoot ........................................................................................................................................ 13-22
P
Parameter
character strings ...................................................................................................................... A-25
indexed ................................................................................................................................... A-25
numeric ................................................................................................................................... A-25
setting ..................................................................................................................................... A-25
template .................................................................................................................................. A-25
Passby ............................................................................................................................................ 5-67
Pause
function ................................................................................................................................... 2-8
key .......................................................................................................................................... 3-10
measurement ........................................................................................................................... 2-8
Performing a Measurement ............................................................................................................ 2-7
Periodic Testing
A-Weighted Levels ................................................................................................................. F-4
Permanent IDs ............................................................................................................................... 4-14
Power
AC Adaptor ............................................................................................................................ 1-18
Battery .................................................................................................................................... 1-16
conservation ............................................................................................................................ 3-8
Display .................................................................................................................................... 3-3
display ..................................................................................................................................... 3-3
External ................................................................................................................................... 1-18
External Power current draw .................................................................................................. C-49
External power current draw .................................................................................................. G-2
Internal .................................................................................................................................... 1-16
key .......................................................................................................................................... 3-3
Monitor ................................................................................................................................... 3-32
power conservation ................................................................................................................. 3-8
Settings ................................................................................................................................... 3-5
settings .................................................................................................................................... 3-5
Powering Up .................................................................................................................................. 4-1
No Display .............................................................................................................................. 3-4
Preamplifier
definition ................................................................................................................................. D-17
input connector ....................................................................................................................... 1-11
Preparing for a Measurement ......................................................................................................... 4-15
Preview Display ............................................................................................................................. 3-10
Print Key ........................................................................................................................................ 3-37
Printing
All, Long Report ..................................................................................................................... 8-14
All, Short Report .................................................................................................................... 8-14
Custom Report ........................................................................................................................ 8-23
Recall Format ......................................................................................................................... 8-7
Reports .................................................................................................................................... 8-2
RTA Reports ........................................................................................................................... 8-26
serial printer connection ......................................................................................................... 8-1
Summary Report ..................................................................................................................... 8-8
tailored report ......................................................................................................................... 8-4
Pulse Tone Definitions
Fall Time ................................................................................................................................ 13-21
Off Time ................................................................................................................................. 13-22
On Time .................................................................................................................................. 13-22
Rise Time ................................................................................................................................ 13-21
Width ...................................................................................................................................... 13-22
Pulse Trigger Voltage
setup ........................................................................................................................................ 7-29
Pulse Width .................................................................................................................................... 13-22
Q
Querying Settings .......................................................................................................................... A-25
R
Random Incidence Correction ....................................................................................................... 7-8
Read Commands ............................................................................................................................ A-7
Recall
Data ......................................................................................................................................... 2-13
Formatted Reports .................................................................................................................. 8-8
ID Setting Files ....................................................................................................................... 7-1
stored data ............................................................................................................................... 4-9
Reference
Level Range ............................................................................................................................ F-1
Point, microphone ................................................................................................................... F-1
Sound Pressure Level ............................................................................................................. F-1
Remote Commands
Setting Commands .................................................................................................................. A-25
Remote Control
"Any Data" Read Commands ................................................................................................. A-21
Addressing Commands ........................................................................................................... A-3
Advance Records .................................................................................................................... A-48
Backup Records ...................................................................................................................... A-49
Calibration History Variables ................................................................................................. A-58
Character String Settings ........................................................................................................ A-29
Commands .............................................................................................................................. A-4
Daily History Variables .......................................................................................................... A-56
Daisy Chain addressing .......................................................................................................... A-3
Data File Commands .............................................................................................................. A-70
Entering Settings .................................................................................................................... A-27
Error Checking I/O ................................................................................................................. A-42
Error Messages ....................................................................................................................... A-63
Exceedance History Variables ................................................................................................ A-49
Find Records ........................................................................................................................... A-49
Group Read Programming ...................................................................................................... A-24
Histogram Reports .................................................................................................................. A-38
Histogram Table Variables ..................................................................................................... A-60
History Data Variables ........................................................................................................... A-49
History Records ...................................................................................................................... A-47
Interface Cables ...................................................................................................................... A-1
Interval History Variables ...................................................................................................... A-51
Keyboard Simulation .............................................................................................................. A-72
Ln Query Commands (SSA) .................................................................................................. A-27
Mode Commands .................................................................................................................... A-5
Modem Control ...................................................................................................................... A-66
Modem Mode ......................................................................................................................... A-66
Numeric Settings .................................................................................................................... A-29
Operation Notes ...................................................................................................................... A-73
Option Settings ....................................................................................................................... A-27
Other Read Commands ........................................................................................................... A-23
Print Commands ..................................................................................................................... A-61
Querying Settings ................................................................................................................... A-25
Read Commands ..................................................................................................................... A-7
RS-232 interface ..................................................................................................................... A-1
RTA Settings Commands ....................................................................................................... A-45
Run Log Variables .................................................................................................................. A-58
Setting Commands .................................................................................................................. A-25
Setting List .............................................................................................................................. A-31
Tailored Report ....................................................................................................................... A-39
Template Settings ................................................................................................................... A-29
Time History Variables .......................................................................................................... A-59
Types of History ..................................................................................................................... A-48
Unsupported Misc. Commands .............................................................................................. A-69
Warnings ................................................................................................................................. A-63
Report
All, Long Report ..................................................................................................................... 8-14
All, Short Report .................................................................................................................... 8-14
Custom .................................................................................................................................... 8-23
Data ......................................................................................................................................... 7-43
History Report ........................................................................................................................ 7-44
Interval Report ........................................................................................................................ 7-44
Peak 1 Histogram ................................................................................................................... 7-43
Peak 2 Histogram ................................................................................................................... 7-44
printing ................................................................................................................................... 8-2
Recall Format ......................................................................................................................... 8-7
RTA ........................................................................................................................................ 8-26
Setup ....................................................................................................................................... 7-43
SPL Histogram ....................................................................................................................... 7-43
Summary ................................................................................................................................. 8-8
Tailored ................................................................................................................................... 8-4
Reset
Using key sequence ................................................................................................................ G-9
Reset Key ....................................................................................................................................... 3-9
RF Emission
Greatest ................................................................................................................................... F-6
group classification ................................................................................................................. C-3
RF Susceptibility
Greatest ................................................................................................................................... F-7
Rise time ........................................................................................................................................ 13-21
Rooms Views ................................................................................................................................. 11-36
RTA ............................................................................................................................................... 7-63
"Then" Settings Menu ............................................................................................................ 11-12
Arm Level ............................................................................................................................... 11-9
Arm Logic In .......................................................................................................................... 11-9
Arm Mode .............................................................................................................................. 11-8
Arm Samples .......................................................................................................................... 11-9
Arm Settings Menu ................................................................................................................. 11-8
Arm Time ............................................................................................................................... 11-9
Auto RT60 .............................................................................................................................. 11-14
Autostore ................................................................................................................................ 11-7
Autostore Settings Menu ........................................................................................................ 11-7
Autostore Views ..................................................................................................................... 11-22
Average
History Check Menu ....11-35
Average Count ........................................................................................................................ 11-13
Avg History Check Menu ....................................................................................................... 11-35
Bandwidth Setting .................................................................................................................. 11-5
ByTime Graph Check Menu .................................................................................................. 11-28
ByTime Spectral History ........................................................................................................ 11-26
ByTime Spectrum Check Menu ............................................................................................. 11-27
Check Menu ............................................................................................................................ 11-31
Detector Setting ...................................................................................................................... 11-5
Display Views ........................................................................................................................ 11-17
End Level ................................................................................................................................ 11-11
End Logic In ........................................................................................................................... 11-12
End Mode ............................................................................................................................... 11-11
End Samples ........................................................................................................................... 11-12
End Settings ............................................................................................................................ 11-11
End Settings Menu ................................................................................................................. 11-11
End Then ................................................................................................................................ 11-12
End Time ................................................................................................................................ 11-12
Exponential Detector Time ..................................................................................................... 11-6
Exponential Store Rate ........................................................................................................... 11-6
Gain Setting ............................................................................................................................ 11-5
Leq .......................................................................................................................................... 11-18
Linear Detector Time ............................................................................................................. 11-6
Live ......................................................................................................................................... 11-18
Logic Output ........................................................................................................................... 11-13
Max ......................................................................................................................................... 11-19
measurement times ................................................................................................................. 11-19
Min ......................................................................................................................................... 11-19
Minimum RT-60 ..................................................................................................................... G-2
Minimum RT-60 value ........................................................................................................... G-3
Note ........................................................................................................................................ 11-15
Pretrigger ................................................................................................................................ 11-7
Random Incidence Correction ................................................................................................ 11-7
Repeat Count .......................................................................................................................... 11-12
Reverberation Time ................................................................................................................ 11-14
Room Views ........................................................................................................................... 11-36
Rooms ..................................................................................................................................... 11-16
Rooms NCB ............................................................................................................................ 11-36
Rooms RC .............................................................................................................................. 11-37
RT-60 display ......................................................................................................................... 11-30
RT60-A/B ............................................................................................................................... 11-15
RTA Views ............................................................................................................................. 11-17
Run Logic In ........................................................................................................................... 11-13
Run on Input ........................................................................................................................... 11-13
Save ByTime .......................................................................................................................... 11-8
Settings Descriptions .............................................................................................................. 11-5
Settings Menu ......................................................................................................................... 11-1
Spacial Average
History .............................11-34
Spatial Ave Check Menu ........................................................................................................ 11-34
Spatial Average Views ........................................................................................................... 11-32
Title Setting ............................................................................................................................ 11-5
Transducer .............................................................................................................................. 11-6
Trig Logic In ........................................................................................................................... 11-11
Trig Samples ........................................................................................................................... 11-11
Trigger Level .......................................................................................................................... 11-10
Trigger Mode .......................................................................................................................... 11-10
Trigger Settings Menu ............................................................................................................ 11-10
Trigger Source ........................................................................................................................ 11-8
Trigger Time ........................................................................................................................... 11-10
Trigger Views ......................................................................................................................... 11-20
Triggering ............................................................................................................................... 11-8
Run ................................................................................................................................................. 7-66
External trigger ....................................................................................................................... G-8
Run Date ........................................................................................................................................ 3-26
Run Log
Check Menu ............................................................................................................................ 7-72
Display .................................................................................................................................... 5-40
Run Time ....................................................................................................................................... 3-26
Run/Stop Key ................................................................................................................................. 3-8
S
SEL Calculations ........................................................................................................................... B-4
Selecting
ID ............................................................................................................................................ 4-11
Measurement Setup ................................................................................................................ 2-6
Views ...................................................................................................................................... 2-11
Serial Address ................................................................................................................................ 3-34
Serial connector ............................................................................................................................. 1-10
Settings
Example .................................................................................................................................. 7-2
Menu ....................................................................................................................................... 4-15
power ...................................................................................................................................... 3-5
Setup
824Utility ................................................................................................................................ 10-10
Key ......................................................................................................................................... 3-14
Menu ....................................................................................................................................... 4-11
Report ..................................................................................................................................... 7-43
SLM Check Menu Options ............................................................................................................ 7-60
Smart Charger ................................................................................................................................ 3-6
Sound
average level (lavg) ................................................................................................................ D-1
day-night average level ........................................................................................................... D-3
energy average(Leq) ............................................................................................................... D-21
exposure .................................................................................................................................. D-18
exposure level ......................................................................................................................... D-18
fixed average .......................................................................................................................... D-20
glossary ................................................................................................................................... D-17
impulse ................................................................................................................................... D-21
instantaneous .......................................................................................................................... D-20
intensity .................................................................................................................................. D-21
moving average ...................................................................................................................... D-19
pressure ................................................................................................................................... D-19
sound pressure level(SPL,Lp) ................................................................................................ D-20
unweighted peak ..................................................................................................................... D-21
weighted peak ......................................................................................................................... D-21
Sound Exposure ............................................................................................................................. 6-8
Sound Level
threshold(Lt) ........................................................................................................................... D-22
Sound Level Measurement ............................................................................................................ 9-1
Averaging ............................................................................................................................... 9-12
Calibration .............................................................................................................................. 9-3
Exceedance Measurements
Sound Level Measurement
Level Trigger 9-16
Linearity ................................................................................................................................. 9-12
Max, Min, Peak ...................................................................................................................... 9-14
Measurement Mode ................................................................................................................ 9-1
Measurement Parameters ........................................................................................................ 9-5
Measurement Range ............................................................................................................... 9-9
Microphone Parameters .......................................................................................................... 9-3
Noise Floor ............................................................................................................................. 9-4
Overload ................................................................................................................................. 9-13
Overload Reset ....................................................................................................................... 9-14
Performing .............................................................................................................................. 9-11
Positioning .............................................................................................................................. 9-7
Preset Integration Time .......................................................................................................... 9-15
SLM Display .......................................................................................................................... 9-9
Timer Mode ............................................................................................................................ 9-15
Under Range ........................................................................................................................... 9-14
Windscreen ............................................................................................................................. 9-7
Sound Power Level ........................................................................................................................ D-21
Sound Pressure Level (see Sound) ................................................................................................ D-20
Sound Speed .................................................................................................................................. D-22
Spatial Average .............................................................................................................................. 11-33
Specifications
AC/DC Output ........................................................................................................................ C-5
AC/DC Output (ISM, LOG) ................................................................................................... C-10
AC/DC Output (SSA) ............................................................................................................. C-13
AUD Mode ............................................................................................................................. C-14
cable driving capacity ............................................................................................................. C-7
general .................................................................................................................................... C-3
ISM and LOG Modes ............................................................................................................. C-9
Main Characteristics ............................................................................................................... C-2
Max Input Voltage .................................................................................................................. C-7
Measurement Range (ISM, LOG) .......................................................................................... C-11
Measurement Range (SSA) .................................................................................................... C-14
Peak Detector .......................................................................................................................... C-10
Peak Range (ISM, LOG) ........................................................................................................ C-12
Physical Characteristics .......................................................................................................... C-6
Power Supply .......................................................................................................................... C-5
Resolution ............................................................................................................................... C-7
RTA Mode .............................................................................................................................. C-18
SSA Mode .............................................................................................................................. C-12
Spectral Lns ................................................................................................................................... 5-20,
7-21
SSA ................................................................................................................................................ 2-2
Measuring Ranges .................................................................................................................. 6-4
Settings ................................................................................................................................... 7-45
Stabilization Time
Environmental Changes .......................................................................................................... F-6
Standby Time ................................................................................................................................. 3-7
Start Level ...................................................................................................................................... 7-21
Starting Measurements .................................................................................................................. 2-8
Statistical Views ............................................................................................................................ 5-37
Stats ................................................................................................................................................ 7-71
Check Menu ............................................................................................................................ 7-71
Status Screen .................................................................................................................................. 8-4
Stop
Date ......................................................................................................................................... 3-26
External trigger ....................................................................................................................... G-8
Function .................................................................................................................................. 2-8
Time ........................................................................................................................................ 3-26
Stopping Measurements ................................................................................................................. 2-8
Storing
Data ......................................................................................................................................... 2-13
System Diagram ............................................................................................................................. 1-13
System Settings .............................................................................................................................. 10-9
T
Takt ................................................................................................................................................ 3-21
Taktmaximal .................................................................................................................................. 2-4
TAL ................................................................................................................................................ 6-2
Template Settings .......................................................................................................................... A-29
THD Measurement
FFT Instrument ....................................................................................................................... 12-8
Tilde Symbol
ID Setup .................................................................................................................................. 4-13
Time
allowed Exposure time(Ti) ..................................................................................................... D-1
On/Off ..................................................................................................................................... 13-22
weighting ................................................................................................................................ D-23
Time History .................................................................................................................................. 6-7
Check Menu ............................................................................................................................ 7-72
Displays .................................................................................................................................. 5-12
Exceedance ............................................................................................................................. 5-55
Max vs Peak level ................................................................................................................... G-7
SSA Display ........................................................................................................................... 5-15
Views ...................................................................................................................................... 5-41
Timer .............................................................................................................................................. 3-23
Timer Mode ................................................................................................................................... 3-25
Title ................................................................................................................................................ 3-15
Title Setting ................................................................................................................................... 7-5
Tools Key ....................................................................................................................................... 3-18
Transducer ..................................................................................................................................... 12-5
Transducer Setting ......................................................................................................................... 7-8
Triggering
Hysteresis ............................................................................................................................... 7-24
Peak Excd Lvl 1 ...................................................................................................................... 7-24
Peak Excd Lvl 2 ...................................................................................................................... 7-24
SPL Excd Lvl 1 ...................................................................................................................... 7-23
SPL Excd Lvl 2 ...................................................................................................................... 7-23
TWA(TC) ...................................................................................................................................... D-22
U
Unenabled IDs
Demo Mode ............................................................................................................................ 2-6
Unpacking and Inspection ............................................................................................................. 1-12
Unsupported Commands ............................................................................................................... A-69
Utility Software. See 824 Utility
V
Vibration ........................................................................................................................................ D-23
View Key ....................................................................................................................................... 3-12
Views ............................................................................................................................................. 2-11
Any Data ................................................................................................................................. 5-7
Any Impulse ........................................................................................................................... 5-8
Any Level ............................................................................................................................... 5-7
Any Time ................................................................................................................................ 5-8
Choices ................................................................................................................................... 2-12
Daily ....................................................................................................................................... 5-57
Daily, wind conditions ............................................................................................................ 5-60
Daily, windy percent .............................................................................................................. 5-62
Exceedance History ................................................................................................................ 5-51
Exceedance Time History ....................................................................................................... 5-55
Exceedance, wind conditions ................................................................................................. 5-54
Exposure ................................................................................................................................. 5-31
general .................................................................................................................................... 5-4
Hourly Leq .............................................................................................................................. 5-63
Intervals .................................................................................................................................. 5-44
Intervals, wind conditions ...................................................................................................... 5-50
Ln Centiles .............................................................................................................................. 5-19,
5-35
Logging SLM ......................................................................................................................... 5-23
Metrics .................................................................................................................................... 5-65
other levels .............................................................................................................................. 5-43
PassBy .................................................................................................................................... 5-67
Run Log .................................................................................................................................. 5-18,
5-40
SLM ........................................................................................................................................ 5-4
SLM Current ........................................................................................................................... 5-25
SLM Overall ........................................................................................................................... 5-25
Spectral Lns ............................................................................................................................ 5-20
SSA ......................................................................................................................................... 5-9
SSA Displays .......................................................................................................................... 5-11
Stats ........................................................................................................................................ 5-37
Time History ........................................................................................................................... 5-41
Wind/Tach .............................................................................................................................. 5-68
Virtual Instruments ........................................................................................................................ 6-1
W
Wavelength(l)
glossary ................................................................................................................................... D-23
Wavenumber
glossary ................................................................................................................................... D-23
Weighting
frequency ................................................................................................................................ D-10
time ......................................................................................................................................... D-23
Weighting Setting .......................................................................................................................... 7-6
Wind/Tach
enable ...................................................................................................................................... 7-28
Pause Enable ........................................................................................................................... 7-29
pulse source ............................................................................................................................ 7-29
pulse trigger voltage ............................................................................................................... 7-29
settings .................................................................................................................................... 7-25
setup ........................................................................................................................................ 7-25
views ....................................................................................................................................... 5-68
Wind Direction Units ............................................................................................................. 7-27
wind display ............................................................................................................................ 5-60
wind exceedance level ............................................................................................................ 7-28
wind hysteresis ....................................................................................................................... 7-29
wind pause enable ................................................................................................................... 7-29
wind units ............................................................................................................................... 7-27
windy threshold ...................................................................................................................... 7-28
Windows printer ............................................................................................................................ 10-30
Windy Percent
views ....................................................................................................................................... 5-62
Windy Threshold
setup ........................................................................................................................................ 7-28
Write
enable ...................................................................................................................................... 3-17
protect ..................................................................................................................................... 3-17
Write-protected IDs ....................................................................................................................... 4-14
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