DTS-2079 DTS-2077 DTS-2075

DTS-2079 DTS-2077 DTS-2075
WAVECREST Corporation
DTS-2079
DTS-2077
DTS-2075
User’s Guide and Reference Manual
207900-03
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:$9(&5(67&RUSRUDWLRQ continually engages in research related to
product improvement. New material, production methods, and design
refinements are introduced into existing products without notice as a
routine expression of that philosophy. For this reason, any current
:$9(&5(67 product may differ in some respect from its published
description but will always equal or exceed the original design
specifications unless otherwise stated.
Copyright 1998-2001
:$9(&5(67&RUSRUDWLRQ
$7HFKQRORJLHV&RPSDQ\
7626 Golden Triangle Drive
Eden Prairie, Minnesota 55344
(952) 831-0030
(800) 733-7128
www.wavecrest.com
All Rights Reserved
Patents Pending
Print rev. 1325
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DTS-207x User’s Guide and Reference Manual
Table of Contents
Preface
Purpose of this Manual........................................................................................ vii
Organization ........................................................................................................ vii
Section 1
General Description
INTRODUCTION............................................................................................... 1
1.1
Hardware Description ......................................................................... 1
1.2
How the DTS Works........................................................................... 2
1.3
Features/Capabilities........................................................................... 3
1.4
External Interface................................................................................ 4
1.5
Liquid Crystal Display (LCD) Menus................................................. 5
1.6
Summary of Menu Selections............................................................. 6
1.7
Modes of Operation ............................................................................ 7
1.8
Arming ................................................................................................ 7
1.9
Controls............................................................................................... 8
1.10
DTS Default Settings .......................................................................... 8
1.11
Taking Time Interval Measurements .................................................. 9
1.12
Summary of Features .......................................................................... 10
1.13
Performance Specifications ................................................................ 11
Section 2
Operation
INTRODUCTION............................................................................................... 15
2.1
Setup, Power-up, and Diagnostics ...................................................... 16
2.1-1 Setup ................................................................................................... 16
2.1-2 Power-up............................................................................................. 16
2.1-3 Diagnostics.......................................................................................... 16
2.2
Control Selection ................................................................................ 18
2.2-1 Menu Scroll/Cursor Control (Up/Down/Left/Right) .......................... 18
2.2-2 Increment/Decrement.......................................................................... 18
2.2-3 Go........................................................................................................ 19
2.2-4 Function .............................................................................................. 19
2.2-5 Pulse Find ........................................................................................... 19
2.3
Menu Selection ................................................................................... 20
Menu #1: Main Function............................................................. 20
Menu #2: Channel Voltage References....................................... 21
Menu #3: External Arming Voltage References ......................... 21
Menu #4: External Arming ......................................................... 23
Menu #5: Arming Sequence Selection........................................ 23
Menu #6: Arming Event Setting ................................................. 24
Menu #7: Voltage Measurement - DC & Strobed....................... 24
Menu #8: Time Filtering ............................................................. 25
Menu #9: Cable Measurement .................................................... 26
Menu #10: Part/Serial Number ..................................................... 26
iii
2.4
2.4-1
2.4-2
2.4-3
2.4-4
2.4-5
2.4-6
2.4-7
2.4-8
2.4-9
2.4-10
2.4-11
2.4-12
2.5
2.5-1
2.5-2
2.5-3
2.5-4
2.5-5
2.5-6
2.5-7
2.5-8
2.5-9
2.6
2.7
2.7-1
2.7-2
2.7-3
2.7-4
2.7-5
2.7-6
2.7-7
Menu #11: Port............................................................................................ 27
Menu #12: Memory - Name/Save/Recall.................................................... 27
Menu #13: Printer........................................................................................ 28
Menu #14: Statistics Setting - Size & Format............................................. 31
Menu #15: Pulse Find Peaks ....................................................................... 31
Menu #16: Statistics I Min/Max & Samples Taken.................................... 31
Mode Selection................................................................................................... 32
Internal Calibration (Labeled INT CAL) ........................................................... 32
Internal Calibration Optimization ...................................................................... 32
External Calibration (Labeled EXT CAL) ......................................................... 33
External Calibration Theory of Operation ......................................................... 33
DC Calibration ................................................................................................... 33
AC Calibration ................................................................................................... 34
Calibration Validity Checks ............................................................................... 34
Burst ................................................................................................................... 35
Special Case ....................................................................................................... 35
Continuous (Labeled CONT) ............................................................................. 35
Idle...................................................................................................................... 35
DC Calibration Reference Voltages ................................................................... 35
Arming Selections .............................................................................................. 36
Arming Source Selection ................................................................................... 36
Automatic Arm (Labeled AUTO) ...................................................................... 36
External Arm (Labeled EXT)............................................................................. 36
Manual Arm (Labeled MAN) ............................................................................ 36
Arming Sequence (Enable) Modes .................................................................... 37
Using the Arming Source & Sequence Together ............................................... 38
Ambiguity........................................................................................................... 40
Gating (Using Arm 2 Input) ............................................................................... 42
Measuring Voltage in Time (Strobing Voltmeter) ............................................. 43
Statistical Calculations - (Sample Size/Set Size/Statistics) ........................................ 44
Installation and Maintenance ............................................................................. 44
Installation Location........................................................................................... 44
Mounting ............................................................................................................ 45
Ventilation.......................................................................................................... 45
Maintaining Proper Instrument Ground ............................................................. 45
Fuse Replacement .............................................................................................. 45
Preventative Maintenance .................................................................................. 45
Intended Use of Equipment................................................................................ 45
Operator’s Quick Reference Guide ................................................................................... 46
iv
Section 3
GPIB Interface
3.1
3.1-1
3.1-2
3.1-3
3.1-4
3.1-5
3.1-6
3.1-7
3.1-8
3.2
3.2-1
3.3
Summary of DTS Commands..............................................................47
System Commands ..............................................................................47
Acquire Commands .............................................................................48
Calibrate Commands............................................................................49
Channel Commands.............................................................................49
Display Commands..............................................................................49
Measure Commands ............................................................................50
Trigger Commands ..............................................................................50
Hardcopy Commands ..........................................................................50
IEEE-488.1 Bus Commands (Hardware).............................................51
Common Commands ...........................................................................51
Root Commands ..................................................................................51
Figures and Tables
Figure 1-1
Figure 1-2
Figure 1-3
Figure 1-4
Figure 1-5
Figure 2-1
Figure 2-2
Figure 2-3
Figure 2-4
Figure 2-5
Figure 2-6
Figure 2-7
Figure 2-8
Figure 2-9
Figure 2-10
Figure 2-11
Figure 2-12
Figure 2-13
Figure 2-14
Figure 2-15
Figure 2-16
Figure 2-17
WAVECREST DTS Time Measurement Instrument .......................... 1
DTS Block Diagram ........................................................................... 2
Front Panel.......................................................................................... 4
Rear Panel ........................................................................................... 5
Rising to Rising Time Measurement .................................................. 9
Simplified Diagram of Operating Setup ............................................. 15
Front Panel.......................................................................................... 17
Rear Panel ........................................................................................... 17
Example of Pulse Find when Activated.............................................. 20
Menu Selections.................................................................................. 22
Arm on Stop and Start ........................................................................ 23
Band Pass Filter .................................................................................. 25
Histogram of Samples......................................................................... 30
Arm on Stop........................................................................................ 37
Arm Stop after Start............................................................................ 38
External Arm....................................................................................... 39
External Arm with Delay.................................................................... 39
Example 1 - Proper Readings ............................................................. 40
Example 2 - Arming Signal Delayed .................................................. 41
Example 3 - Positive & Negative Readings........................................ 42
Gating Mode ....................................................................................... 42
Delayed Scan for Measuring Voltage in Time.................................... 43
Table 1-1
Table 1-2
Table 2-2
DTS Default Settings .......................................................................... 9
Symbol Description Table .................................................................. 13
Operator’s Quick Reference Table ..................................................... 46
v
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iv
35()$&(
PURPOSE OF THIS MANUAL
This manual has been prepared to help the user achieve maximum results from the DTS in the
shortest possible time. The manual’s physical size, format, and content is designed to make it
easy for the new user as well as the established user.
ORGANIZATION
The manual is divided into three sections, each dealing with one phase of the instrument’s
operation. The following is a brief description of the information contained in each section.
For quick reference to specific information, refer to the Table of Contents.
Section 1 — General Description
Introduces you to the DTS. Capabilities and features are described. All hardware relating to
the use of the DTS is described. A complete table of the DTS performance specifications can
be found at the end of this section.
Section 2 — Operation
This section provides step-by-step procedures for all phases of operation, including power-up
and diagnostics, calibration and mode selection, triggering, controls, and selecting/using menus.
Diagrams outlining the sequence of operation provide detailed steps for getting the most from
your DTS and using it to its full potential. Also included is an Operator’s Quick-Reference
Table that conveniently allows at-a-glance referencing for controls and indicators.
Section 3 — GPIB Interface
Includes various parameters, value, and codes necessary for implementing remote control of
the DTS via the IEEE-488 Interface.
vii
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viii
6(&7,21²*(1(5$/'(6&5,37,21
This section contains a general overview and introduction to the :$9(&5(67 DTS-207x Digital
Time Scope. It also presents its capabilities, features and a brief description of the instrument’s
hardware. Performance specifications are included in this section.
INTRODUCTION
The :$9(&5(67 DTS-207x Series Digital Time Scope (DTS) is designed for applications
where timing accuracy is critical. The DTS provides direct, real-time measurements without the
associated errors during the sampling and transformation of data while waiting for a waveform to be
displayed. The result is a precision instrument capable of measuring time between two events with a
resolution of 800 femtoseconds and single-shot measurement accuracy of ±25 picoseconds (ps).
Figure 1-1 :$9(&5(67 DTS Time Measurement Instrument
The DTS represents a dramatic departure from the traditional digital sampling oscilloscope (DSO)
approach to critical timing functions. The DSO approach takes a time frame and then measures the
number of events occurring within that time frame to arrive at a figure for elapsed time between
each event. The DTS approaches the measurement algorithm as absolute; time between any two
events is actual, measurable and quantifiable.
The DTS is intended for AC characterization, with the added benefit of N.I.S.T. traceability, in
applications ranging from ATE test head deskew to bench top device test and computer clock
distribution. In addition, the DTS is well suited for scientific and engineering applications which
require timing accuracy and resolution more precise then other available instruments can provide.
The DTS achieves greater accuracy with fewer readings in less time than digital scopes or other
types of time domain measurement devices.
Long-term measurement accuracy and linearity of the DTS is due to built-in calibration options that
can be initiated by the user at any time.
1.1 HARDWARE DESCRIPTION
The DTS incorporates a three-card timing measurement subsystem, a single-card Central Processing
Unit, a comparator card, a front panel for operator control of the instrument, ovenized crystal oscillator,
power supplies, and an IEEE-488 interface. Signals to the DTS are inputted through SMA connectors on
the front panel. The front panel (Figure 1-3) provides the means for controlling, monitoring, and
communicating with all time measurement functions of the DTS.
Section 1 | General Description | 1
1.2
HOW THE DTS WORKS
The key to understanding the :$9(&5(67 DTS line of products is by comparing arming and
triggering devices.
Oscilloscopes have triggered time bases that require triggering to start the time base sweep
while events are displayed with respect to linear time.
The DTS is not triggered but ARMED, or ENABLED, to make a measurement of the
next event that occurs on the input channels.
V. Ref Start
Arming/Enabling Mux
Ch1
Start Path
CPU Ready
Ch2
Stop Path
V. Ref Stop
Arm 1
100 MHz Ovenized Oscillator
V. Ref Arm 1
Arm 2
V. Ref Arm 2
Figure 1-2 DTS Block Diagram
Figure 1-2 shows a simplified block diagram of the DTS. The 50Ω-to-ground inputs of the DTS
feed dual comparators on each channel. This enables the DTS to measure events such as Period,
Pulse Width and Rise/Fall time on a single channel in One-Shot mode. Propagation delay (TPD)
is measured using both channels.
Voltage Reference Start (V. Ref. Start) and Voltage Reference Stop (V. Ref. Stop) set the threshold
trip points for the comparator inputs. As the diagram shows, there is a Start and Stop reference
voltage on each channel.
“Auto Arming” enables the DTS to asynchronously, or randomly, measure time events. Selecting
an external arming mode option enables the DTS to synchronize with the event to be measured much
like an oscilloscope does when it is triggered. “Arming” the DTS is not the same as triggering an
oscilloscope, just similar.
The External arming inputs go to logic circuits within the DTS and, in conjunction with the
“Enable Modes,” select whether the DTS is to be synchronous or asynchronous with respect to
the signal to be measured.
The last signal that is of importance is the “CPU ready” signal which is generated whenever the CPU
is ready to process another measurement. This time duration is program controlled so that the
measurement or “Burst” rate can be varied.
2 | Section 1 | General Description
1.3
FEATURES/CAPABILITIES
The DTS features and capabilities include:
• Measuring several different characteristics of an electrical pulse.
Those characteristics are:
– Propagation Delay (TPD++, TPD--, TPD+-, and TPD-+)
– Rise/Fall Time (TT+, TT-)
– Period/Pulse Width/Frequency (PW+, PW-, PER, FREQ)
– Cable Measurement
– Strobing voltmeter - to digitize input waveforms
– 16-bit DVM on each channel
• Taking one measurement with a single-shot accuracy of ±25ps, or as many as 1,000,000
readings, and recording statistical data output with an accuracy of ±10ps.
• Two different operational modes and three different triggering methods.
• Both an internal and external AC and DC calibration mode.
• A front panel incorporating a two-line, 40-character liquid crystal display (LCD) for
access to a complete range of menus.
• Input voltage levels that can be set for rising or falling signals from ±1.1 volts in 0.15mV
increments. Minimum pulse amplitude of only 50mV peak to peak is required.
• A PULSE FIND capability that locates the signals and automatically sets voltage inputs
required for measurements. Selectable for finding either peaks or flat spots.
• System capability of taking 40,000 measurements per second and handling pulse trains up
to 1630MHz for the DTS-2079, 1300MHz for the DTS-2077 and 800Mhz for the DTS-2075.
• IEEE-488 Interface that allows for standardized integration into OEM products, giving
the user remote capabilities with selectable addressing and with an optional SCSI
interface available.
Section 1 | General Description | 3
1.4
EXTERNAL INTERFACE
Four external inputs and two signal outputs are routed through SMA connectors on the front
panel directly into the DTS. The six SMA connections on the front panel are:
CH1 ............... Used for a START event input pulse for TPD measurements. Inputs START
and STOP event pulses for all other measurement modes.
CH2 ............... Used for a STOP event input pulse for TPD measurements. Inputs STOP and
START event pulses for all other measurement modes.
External ....... Used for AC Deskew and DC offset and gain of DTS Inputs and for Coax
Cal 1/Cal 2 Cable Delay measurement.
External ....... Used as input for the External Arm, which starts the measurement of the next pulse
Arm1/Arm2 seen on the CH1 and CH2 connectors when Ext. Arm mode has been selected.
Standby
ON/OFF
MENU SCROLL
CONTROL (UP,
DOWN, LEFT, RIGHT)
LCD
FUNCTION
INCREMENT
CHARACTER
VALUE
GO
INTERNAL
CALIBRATE
EXTERNAL
CALIBRATE
DECREMENT
CHARACTER
VALUE
EXTERNAL ARM
BURST
CONTINUOUS
AUTO ARM
MANUAL ARM
CH1
SMA CONN.
CH2
SMA CONN.
CH1
SMA CONN.
CH2
SMA CONN.
Figure 1-3 Front Panel
4 | Section 1 | General Description
EXTERNAL
ARM 1
EXTERNAL
ARM 2
The rear panel (Figure 1-4) contains power and reset buttons as well as five additional interfaces:
AC Power/Line............. Used for the incoming AC power cord. When the power switch is ON,
Filter/Fuse
the crystal oven is ON. Power to the remainder of the system is controlled
by the STANDBY power switch on the front panel. The AC power
may be either 110VAC ±20v, or 220VAC ± 40v, single- phase. The
DTS typically draws 1.8 Amps, and is fused with two, 6.3 Amp, slowblow, 5x20mm fuses (:$9(&5(67 part number 400067-66).
IEEE-488........................ Permits remote operation of the DTS. Section 3 contains specific
Connector
information and instructions concerning IEEE-488 protocol.
Oscillator Reference.. Provides a ± 100mV 100MHz signal to check the accuracy of the
Out Signal - SMA
internal 100MHz Frequency Standard.
RS232/SCSI/ ................. Provides for option connections.
PARALLEL
RESET............................ A push-button is provided to reset the system. The power-up
diagnostics are not performed during a reset.
Vref ............................. Provides a reference voltage to check the accuracy of the internal
Voltage Standard. The voltage should measure +1mV of the voltage
indicated on the calibration label.
ID Label
Reset
Interface Ports
Calibration Label
Oscillator
Reference Out
Reference Voltage
Output, ~5vdc
Figure 1-4 Rear Panel
1.5
LIQUID CRYSTAL DISPLAY (LCD) MENUS
A two-line, 40-character liquid crystal display (LCD), located on the front panel of the
instrument, provides access to a variety of menus or screens. With the arrow keys, the user
can scroll to the appropriate menu to store information, view sampling information or define
program-specific measurement parameters as required by the customer's application. The LCD
(display) is also used to alert the operator, prompt action where necessary and displays
system status.
Section 1 | General Description | 5
1.6
SUMMARY OF MENU SELECTIONS
The operator has the option of selecting any one of 16 menu screens. These menus present the
operator with feature or parameter selections for I/O addressing, memory storage, printing, statistics,
pulse find, AC and DC measurement, cable measurement and filtering.Figure 2-6 illustrates the
order of the menus.
•
Main Function (Default Menu) - Provides for the selection of specific functions which define and
set up parameters associated with a function. Provides for the selection of a percentage of peak that the start/stop
references will be set to during a pulse find, the selection of the input channel to be used during
a measurement and displays the average and peak jitter after a measurement is completed.
• Time Measurement Parameters
Start/Stop Channel Voltage References - Displays the start and stop reference voltages
found during a pulse find. Provides an input of user defined reference voltages. The information
for each reference voltage is the edge direction, polarity and level.
External Arming Reference Voltage - Displays the external arming inputs for Arm 1and
Arm 2 recorded during a pulse find. Provides an input of user defined arming reference voltages. The information
for each reference voltage is the edge direction, polarity and level. Provide the turning
on/off of the Gating feature.
External Arming Selection - Select which arming input is used to arm the Start or Stop event.
Arming Sequence Selection - Selects the arming sequence to use in making a measurement.
Arm on Nth Event - Provides for the input of start and stop counts that will define the time of the
respective arming of start and stop.
•
Voltage Measurement Parameters - Selects the type of dc measurement that will be taken
when a function button is pressed. The three types are DC, Strobed by Arm 1 and Strobed by Arm 2. Provides
for the selection of input channel for measuring a voltage and for the input of a delay, from arming, for
strobing a voltage measurement as well as displays the voltage level of a dc or strobed voltage measurement.
•
Time Filtering - Provides an input of filtering limits, minimum and maximum, and turning the filtering
feature on or off.
•
Cable Measurement - Displays the average reading after a cable measurement and turns the cable
measurement on or off.
•
Serial and Part Numbering - User input of serial/part number of device being tested.
•
Port Addresses/Pulse Find Mode/Clear - Sets GPIB and SCSI addresses. Select Pulse Finder
modes of PEAK or FLAT. System Clear.
•
Memory - Provides for the saving, recalling and naming of ten (10) sets of parameters.
•
Printer - Provides the selection and control of printing.
•
Statistics Settings - Sets the sample and sets size and sets the unit the statistics will be displayed in.
•
Pulse Finder Peaks - Displays the minimum and maximum peak voltages found with a pulse find.
•
Statistics I - Displays the sample size and samples completed. Displays the minimum and maximum
readings of a time measurement. Displays duty cycle.
6 | Section 1 | General Description
1.7
MODES OF OPERATION
The DTS has five modes of operations the user can select. Four modes are controlled by pushbutton switches located on the front panel. At power on, the DTS is placed in the first mode,
Idle, which is a wait state. These five modes are:
1.8
Title
Function
Idle
The DTS is in the wait state if none of the other modes have been selected. Power On
or completion of Burst mode places the DTS into Idle mode.
EXTernal
CALibration
Used for External Calibration/Deskew of the CH1/CH2 inputs.
Automatically measures and corrects for input variations of the CH1/CH2 comparators,
then stores these values in memory to be used to correct all future measurements. Also
used to perform a DC gain and offset calibrations of the test probes.
INTernal
CALibration
The DTS automatically calibrates itself internally to a N.I.S.T. traceable 100Mhz
ovenized crystal oscillator in approximately 11 minutes.
BURST
The DTS will complete the number of readings equal to the sample size selected and
then stop. When the sample size is reached, the DTS displays the computed data.
CONTinuous
Continuously measures pulses in this mode. Once the number of pulses measured
equals the sample size, the newly computed data is displayed and the process begins
again to collect a new series of measurements equal to the sample size.
ARMING
The DTS has three user selectable arming capabilities. These selections are activated using three
push-buttons located on the front panel. The arming capabilities are:
Title
Function
MANual
Activates the system to take measurements when the GO button is pushed. Once
armed, the DTS measures the next pulse presented. Every time the GO button is
pushed, the sample size is incremented. The statistics are not updated until the
sample size has been achieved. If Burst mode is selected, no further pulses are
accepted after sample size is achieved; if Continuous is selected, a new series of
measurements will begin after the sample size is achieved.
AUTOmatic
This allows automatic measurement to the sample size, based on the edges of the
Start/Stop pulses. If Burst mode is selected, no further pulses are accepted after the
sample size is achieved; if Continuous is selected, a new series of measurements will
begin after the sample size is achieved.
EXTernal
Allows external signal source to arm the DTS for measurements. Once armed, the
DTS measures the next pulse presented. If Burst mode is selected, no further pulses
are accepted after sample size is achieved; if Continuous is selected, a new series of
measurements will begin after the sample size is achieved. Provides Gating/Burst
Trigger modes and external strobe for digitizing waveforms.
Section 1 | General Description | 7
1.9
CONTROLS
The DTS has five control functions that are available to the user. These five functions are located
on the front panel and are push-button switches (refer to Figure 1-3). Two of the functions have
multiple push-buttons. The five control functions are:
Title
Function
Menu Scroll
Allows the user to scroll from menu to menu and field to field inside a menu.
There are four push-buttons in this function: UP, DOWN, LEFT and RIGHT.
Increment/
Decrement
Allows the user to increase or decrease values in selected fields or change options,
both contained within the menus. There are two push-buttons in this function:
INCREMENT or DECREMENT.
Go
Allows the user to restart the DTS after certain modes that require external action are
taken by the user. The DTS always gives a prompt on the menu for the GO function.
Function
The FUNCTION push button is used for different functions for the different menus.
Menu Function:
Memory ....................................... Initiate RECALL/SAVE.
Statistics I .................................... Calculates unfiltered statistics.
Printer.......................................... Initiate a print.
Pulse Finder Peak ........................ Initiate a pulse find.
Main Function ............................. Initiate a pulse find.
Time Measurement Menu #2....... Initiate a pulse find.
Time Measurement Menu #3....... Initiate a pulse find.
Voltage Measurement.................. Initiate DC or strobed measurement.
Standby (Power)
1.10
Powers system On or Off. When power is On, the LCD background is illuminated
and remains on as long as power is applied to the system. The crystal oven is
activated whenever the power cord is connected to the AC power source and the main
power switch on the back panel is on. The front panel rocker switch controls the
power to other DTS circuits.
DTS DEFAULT SETTINGS
Function
Trig %
Channel
Arm
Source
Arming
Sequence
Start
Count
Stop
Count
TPD++ --------- 50-50------------- 1-2 -------------- Auto-------------Arm on Stop --------- 001 ------------ 001
TPD------------- 50-50------------- 1-2 -------------- Auto-------------Arm on Stop --------- 001 ------------ 001
TPD+----------- 50-50------------- 1-2 -------------- Auto-------------Arm on Stop --------- 001 ------------ 001
TPD-+---------- 50-50------------- 1-2 -------------- Auto-------------Arm on Stop --------- 001 ------------ 001
TT+------------- 10-90-------------- 1 --------------- Auto-------------Arm on Stop --------- 001 ------------ 001
TT--------------- 90-10-------------- 1 --------------- Auto-------------Arm on Stop --------- 001 ------------ 001
PW+ ------------ 50-50-------------- 1 --------------- Auto-------------Arm on Stop --------- 001 ------------ 001
PW-------------- 50-50-------------- 1 --------------- Auto-------------Arm on Stop --------- 001 ------------ 001
Period ---------- 50-50-------------- 1 --------------- Auto-------------Arm on Stop --------- 001 ------------ 002
Frequency ----- 50-50-------------- 1 --------------- Auto-------------Arm on Stop --------- 001 ------------ 256
Table 1-1 Default Settings
8 | Section 1 | General Description
1.11
TAKING TIME INTERVAL MEASUREMENTS
All time interval measurements made with the DTS follow a simple, four-step progression;
Arm, Function, Enable and Execute. The following should be considered before executing
a measurement:
•
•
•
•
What Arming source is required to make the measurement?
What Function is being measured?
What Enable mode is required to make the measurement?
Execute time interval measurement.
Whenever a time interval measurement is made, all four steps are completed. Using the DTS is
simple and repeatable because all four steps are defaulted for each measurement function of the
instrument. These defaults can be changed by the user as desired.
In addition to the default settings shown in Table 1-1, all channel Voltage References are set
to 0.00v unless changed by the execution of a PULSE FIND or set externally by the user. The
PULSE FIND command will set the reference voltages for each channel based on the TRIGGER
percent indicated in Menu #1 (See Section 2.3).
Ch1
Start
Path
Ch2
Stop
Path
1. "CPU Ready"
enables the Enable
mode in Step 2.
3. The TPD++ event
will then be measured.
2. If Auto Arm on Stop was selected,
first STOP pulse after "CPU Ready"
will arm DTS.
Figure 1-5 Rising to Rising Time Measurement
In Figure 1-5, a measurement is taken from the rising edge of Channel 1 to the rising edge of
Channel 2. The instrument is set up for an arming source of Auto and an arming sequence of
the Stop path (commonly stated as Auto on Stop).
The sequence of events that will happen in Figure 1-5 are:
1. The DTS signal ‘CPU ready’ provides a pre-arm.
2. The first (1) rising edge on Channel 1 stop path will arm the instrument.
3. The next rising to rising measurement between Ch1 and Ch2 will be taken.
If a sample size of 1000 was selected, then the above step will be repeated 999 more times. The
results of all 1000 one-shot measurements are stored in DTS memory and statistically analyzed
to display the AVERAGE, ±PEAK and RMS JITTER. The ±PEAK is the min/max spread of
the 1000 measurements. The RMS JITTER is the true statistical standard deviation for the
1000 measurements and represents the RMS jitter in a Gaussian distribution. The AVERAGE
is the center of the distribution.
Section 1 | General Description | 9
The instrument also has the ability to measure the voltage in time (strobed) with a resolution as
fine as 10ps. This can be used to help the user determine where to set the reference voltages.
With the help of a host computer, the complete waveform can be graphically displayed using
:$9(&5(67’s Virtual Instrument Signal Integrity™ software.
In addition, the instrument also has the ability to Gate the arming of the instrument. The GATING
mode is useful if the device to be tested has a “ready or lock” signal such as when a PLL is locked
onto some serial pattern. For instance, the user may want to measure only the period when the PLL
is locked while the data is high and measure again when the PLL is not locked while the data
is high to see the difference in frequency and jitter.
1.12
Summary of Features:
• 800 femtosecond resolution
• ±25ps single-shot accuracy
• ±10ps average accuracy
• 15,000 readings/sec. to 40,000 readings/sec. with “HiPer” option
• Input signal bandwidth of 2GHz or greater
• Time measured between ±2.5 seconds.
• Independently programmed voltage threshold ±1.1v
• Auto calibration
• IEEE-488 interface with SCSI option
• N.I.S.T. Traceable
• Strobing voltmeter
• 16-bit DVM to measure voltage on channels
• Digital filters to select data to measure
10 | Section 1 | General Description
1.13 PERFORMANCE SPECIFICATIONS
•
Timing Measurement Performance
Single Shot Accuracy .............................±25ps @ calibration frequency (3 sigma limit)
Accuracy with Averaging .......................±10ps @ calibration frequency (0.5v rms input)
±30ps over entire input range
Repeatability...........................................±2.0ps typical @ sample size = 1,000/burst
Resolution...............................................800fs internal
0.001fs displayed
Range......................................................0 to ±2.5 seconds
Measurement Rate ..................................>40,000-measurements/second maximum
Internal Jitter (Noise Floor) ....................6ps rms (3ps typical)
•
Input Signal Characteristics
Input Threshold Resolution ....................±1.1v, 0.15mV increments
Sensitivity ...............................................100mV
Impedance ..............................................DTS-2079: 50Ω ± 5Ω to 1.63GHz
DTS-2077: 50Ÿ“ŸWR*+]
DTS-2075: 50Ÿ“ŸWR*+]
Maximum Frequency..............................DTS-2079: 1630MHz
DTS-2077: 1300MHz
DTS-2075: 800MHz
Maximum Data Rate...............................DTS-2079: 3.2Gbps
DTS-2077: 2.5Gbps
DTS-2075: 1.3Gbps
Minimum Pulse Width............................DTS-2079: 300ps
DTS-2077: 380ps
DTS-2075: 625ps
Connectors..............................................SMA type
Slew Rate Bandwidth .............................DTS-2079: > 4.5GHz
DTS-2077: > 2GHz
DTS-2075: > 2GHz
•
(
.22
Minimum Input Rise Time (20%-80%)
)
Arming Functions
Automatic ...............................................Auto arms, starts and stops on incoming edges
Enable Modes:
Arm on Stop........................................Enable measurement on start channel 1
Arm on Start........................................Enable measurement on start channel 2
Arm Start First ....................................Enable measurement after start occurs, requires 1ns setup time
Manual....................................................Arms inputs with GO push-button to accept next incoming edge
External:
Input Threshold...................................±1.1v
Voltage Resolution..............................1mV
Sensitivity ...........................................25mV
Impedance........................................... “ WR*+]
Connectors ..........................................60$W\SH“ WR*+]
Max. Frequency......................................DTS-2079: 1000MHz
DTS-2077: 1000MHz
DTS-2075: 800MHz
Section 1 | General Description | 11
•
Statistical Functions
Average.................................................. Average of n readings
Jitter RMS
One standard deviation (1 sigma)
Min/Max Reading.................................. Lowest/Highest Reading
Peak ....................................................... +/- Difference between Min & Max Measurements divided by 2
•
2-Line LCD Display with Menu
Channel 1............................................... Voltage threshold; rising/falling edge
Channel 2............................................... Voltage threshold; rising/falling edge
Pulse Finder ........................................... Automatic selection, 50%, 10-90%, 20-80%, points of input signal
Arm........................................................ Voltage threshold
Force...................................................... Auto Trig. on Start; Auto Trig. on Stop; Enable Stop after Start
Filters..................................................... Set within ±2.5s, 1ps resolution (With filters on, max. samples is 8k)
Presets.................................................... Ten (10) memories
Set number of samples........................... 1 to 1,000,000
IEEE-488 and SCSI ............................... Select address
Choice of Display Units......................... Auto scale, seconds, ms, µs, ns, ps
Cable Length Measurement ................... Time delay
•
Measure Modes
Burst ...................................................... Perform n measurements, halt and update display
Continuous............................................. Continuously perform n measurements, update display after
each reading
•
Calibration Modes
Internal................................................... Internal calibration to self-contained N.I.S.T. traceable standard
in approx. 11 minutes
Extended Internal................................... For embedded code version 1.98 or greater. From approximately
5.5 minutes to approximately 2.5 hours via GPIB commands with user
program or Virtual Instruments Signal Integrity™, version 3.20 or greater.
External.................................................. Deskew/calibrate inputs
•
Timebase
High stability, low phase noise, ovenized, N.I.S.T. traceable, crystal oscillator.
Frequency .............................................. 100MHz
Aging/day .............................................. 5 x 10-8 seconds
Aging short term .................................... 5 x 10-11 seconds
Accuracy................................................ 1 x 10-6 seconds
•
IEEE-488 Interface
All front panel functions (and more) can be programmed.
12 | Section 1 | General Description
• Power Requirements
Voltage ...................................................100-115/230VAC ±10%
Frequency ...............................................47-63Hz
Power......................................................Less than 300W
• Environmental Requirements
Indoor use only:
Elevation (Altitude) ……………………to 6500 feet (2000 meters)
Temperature............................................Ambient room 15°C to 35°C (59ºF to 95ºF)
Temperature range..................................Calibration Temperature ± 5°C
to maintain Calibration
Humidity.................................................1 to 85% R.H. (Non-condensing)
Over Voltage Installation Category ……CAT II
Pollution Degree ……………………….2 per IEC664
• Size/Weight
Size .........................................................59.79cm (L) x 44.18cm (W) x 19.05cm (H)
Weight ....................................................17.5kg (38.5lbs)
All specifications are subject to change without prior notice.
Section 1 | General Description | 13
Table 1-2
Symbol Description Table
Specific cautionary or warning information may appear on the product or in this
manual where applicable. The following is a summary of their meanings.
CAUTION
This statement identifies conditions that can result in
damage to the DTS or property
WARNING
This statement identifies conditions that can result in
personal injury or loss of life.
!
This symbol indicates applicable cautionary information
is noted.
Protective earth ground.
14 | Section 1 | General Description
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This section leads you through the sequence of steps for using the DTS-207x. Flow diagrams and figures
supplement the textual descriptions. The diagrams have been designed as an aid for repeated referencing when
frequent recall of a particular step is required.
INTRODUCTION
Figure 2-1 is a simplified diagram of an operating setup and will be used as a reference to clarify statements in the
operation. For example, the device under test (DUT) output connection is defined as the connection point of the
cable at the DUT, not at the DTS For best results, all cabling must be double-shielded 50Ω coaxial. Also, highresolution accuracy depends on using good interface techniques. It is necessary to follow standard microwave
techniques for 50Ω environments.
The DTS does accept passive or active probe inputs with a 50Ω environment. Ideally, for optimum signal integrity,
all external signals should terminate to 50Ω environments at the SMA connectors. The 50Ω inputs are terminated
to ground.
Signal
Generator
CH1
SMA Conn.
External
Arm 1
External
Arm 2
CH2
SMA Conn.
Device
Under
Test
Figure 2-1 Simplified Diagram of Operating Setup
The DTS follows a series of events with each power-up. The normal operating procedure required from power-up
through the use of the instrument’s full capabilities is divided into six parts:
2.1
Set-up, Power-Up, and Diagnostics
2.2
Control Selections
2.3
Menu Selections
2.4
Mode Selections
2.5
Arming Selections
2.6
Calculations
2.7
Installation and Maintenance
Refer to Figures 2–2 and 2-3 for identification and locations of push-buttons, indicators, connections or other
components specified in the operating procedures contained in this section.
Section 2 | Operation | 15
2.1
SETUP, POWER-UP, AND DIAGNOSTICS
This subsection covers the setup, power-up, and diagnostics for the DTS. Also covered are the functions of
the IEEE-488 connector and the AC power switch.
2.1-1 SETUP
Refer to Section 2.7 for detailed instructions on the proper installation, ventilation, fuse replacement and
use of the DTS unit. A spare fuse is provided inside the fuse compartment. Refer to page 12 for power
requirements and Figure 2-3 for the location of AC power connection on the back of the DTS. Plug the
unit into a compatible AC power source.
IEEE-488
If IEEE-488 GPIB is used, plug the IEEE-488 cable into the connector at the rear of the unit. Refer to
SECTION 3 for information and instructions on the IEEE-488 protocol.
AC POWER SWITCH
The main AC power switch, located on the rear panel, controls power to the 100MHz crystal oven independent
from rest of the DTS unit. If the main AC power switch is ON, the oven is always ON. The standby switch on
the front panel must also be ON to provide power to the rest of the device.
2.1-2 POWER-UP
Push the Standby switch on the front panel. The LCD (display) will illuminate.
IMPORTANT: If the DTS is powered Off for any reason, wait for 5 sec. before powering back up.
This allows the power supplies to properly discharge avoiding potential damage.
2.1-3 DIAGNOSTICS
The first in a series of self-diagnostics will begin on power-up.
Test Name
Description
CPU.............. Test central processing unit circuits
Test Timer
Test Memory
Test Math processor
DCB.............. Test Digital Control Board
MSU ............. Test Measurement Setup Board
IQM............... Test Interval Quantizer Board
All of the above tests take less than 5 sec. to run. Upon successful completion of these tests, the DTS will
display the default menu, which is the Main Function (#1) menu (See Section 2.3).
IMPORTANT: The DTS is a precision instrument. The unit operates best after a minimum
30-minute warm-up period. Acceptable readings can be obtained after unit
warm-up period and calibration. See SECTION 2.4 for calibration information.
16 | Section 2 | Operation
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CONTROL SELECTION
Control Selection consists of four groups of push-buttons that provide the user control of the DTS from
the front panel. These four push-buttons are:
Menu Scroll/Cursor (UP/DOWN, LEFT/RIGHT)
Increment/Decrement
Go
Function
2.2-1 MENU SCROLL/CURSOR CONTROL (UP/DOWN, LEFT/RIGHT)
These four triangular push-buttons are located to the right of the LCD (display) and provide the user access
to all the menus of the DTS unit.
The UP/DOWN buttons permit scrolling up or down to select a desired menu on the LCD. The two-line
menus are scrolled between the two lines by using these buttons also.
The LEFT/RIGHT buttons permit movement of the cursor left or right to the desired data entry field within
the menu screen.
2.2-2 INCREMENT/DECREMENT
These two rectangular push-buttons are located below and to the right of the LCD display. The top pushbutton is the INCREMENT and the bottom push-button is the DECREMENT.
These two push-buttons enable the user to increase or decrease values in the menu field, or change options
in the menu field that have already been selected. For those fields that have multiple values or options,
each time the button is pushed the LCD will show the next value or option.
IMPORTANT: The DTS has no “enter” push-button to capture the field that is being
changed. Once the user has finished changing the field, the DTS must
recognize the changed field. This is accomplished simply by moving
the cursor off the field that was recently changed. Once the selection
of any set value or option has been made, the cursor must be moved
off the field for the selected value or option to be entered and recognized
by the DTS. (The only instance where this is not true is in The “Main
Function” menu and “Cable Delay Measure” menu, where turning cable
measure “On” immediately enables this mode without moving the cursor
any further.)
18 | Section 2 | Operation
2.2-3
GO
This rectangular push-button is located below the LCD and to the left of the Increment push-button. This
button is used when the user is required to initiate an action external to the DTS before proceeding. The
DTS will always prompt the user as to what is needed by displaying a message on the LCD and
illuminating the LED adjacent to the push-button.
There are two conditions during which the GO button will be pushed. These are:
Conditions
Action
External Calibration.......................................User must attach the cables which are
being compensated, selects AC and/or DC
calibration
Internal Calibration........................................Causes new calibration data to be taken
Strobe Calibration..........................................Causes strobe delay calibration to be taken
Manual Trigger ..............................................User is performing one reading at a time
2.2-4
FUNCTION
This rectangular push-button is located to the right of the two increment push-buttons. The Function
push-button has many uses depending on the selected menu. These are:
Action
Result
If pushed when in the Memory menu #12:........................ Recalls/Stores set-ups under the selected name
If pushed when in Statistics I menu #16 .......................... DTS calculates unfiltered data and updates menus
filter is On, mode is Idle:
If pushed when in Printer menu #13: ................................ Initiates a print.
If pushed when in Pulse Find, Main Function .................... Pulse Find is executed.
or Time Measurement menus - #1, #2, #3 and #15:
If pushed when in Voltage Measurement menu #7:...... Initiates a DC or strobed voltage measurement
2.2-5
PULSE FIND
There are several different results possible when the Pulse Find has been activated (Figure 2–4). Pulse
Find sets Start and Stop threshold reference voltages based on the minimum and maximum pulse level
found on each channel. In the Main Function (#1) menu, the following applies:
Function
Default
If FCN: TPD++, --, +-, -+,....... CH1 and CH2 voltages are set to 50% of each input channel
Period, PW+, -:
If FCN: TT+: .......................... The Pulse Find sets the Start reference voltage at 10% and the Stop
reference voltage at 90% point of the respective pulses presented at the
CH1 and CH2SMA connectors (refer to Note below)
If FCN: TT-: ........................... The Pulse Find sets the Stop reference voltage at 10% and the Start
reference voltage at 90% point of the respective pulses presented at the
CH1 and CH2 SMA connectors (refer to the Note below)
NOTE: If the Pulse Find is activated and no signal is on either Channel 1 or 2, the unit may find
termination voltage levels. If it finds no signal, including termination voltages, it will return
to its original setting.
Section 2 | Operation | 19
Pulse Find generally takes longer to find a small amplitude pulse. Pulses should occur at a reasonable rate
in order for the Pulse Find to work. The recommended minimum rate is 1,000/second.
Auto Finds the
Peak Levels
Auto Finds the
Flat Spot
CH1
CH2
Calculates the 50%, 20%-80%
and 10%-90% for each channel
depending upon the
mode.
Figure 2-4 Example of Pulse Find when activated
2.3
MENU SELECTION
The user has the option of selecting any one of 16 possible menu screens. The grouping of these menus is
graphically illustrated in Figure 2-5.
Upon Power-Up, the display screen defaults to the Main Function menu (Menu #1). Any desired menu can
then be selected by pressing either the UP or DOWN menu scroll push-buttons directly to the right of the LCD.
For example, with the default menu displayed, pressing the UP button one time steps the display to Menu #16;
pressing it again steps the display to Menu #15, etc. Conversely, pressing the DOWN button scrolls the display
to Menu #2 and continues through #16.
Within any menu screen, a blinking cursor appears, designating the field, which is active. This cursor may be
moved within the menu window by pressing either of the LEFT or RIGHT directional arrows.
Once the cursor has been positioned to the desired field, programming parameters within that field can be
entered by using the INCREMENT/DECREMENT buttons.
MENU #1: Main Function
FCN: TPD++
MEAS:
TR: 50% - 50% CH: 1-2
RG = ¦
JT =
FCN - Permits the user to select one (1) of ten (10) different measurement functions: TPD++, TPD--,
TPD+-, TPD-+, TT+, TT-, PW+, PW-, Period and Frequency. In addition, this menu allows the user to
select different start and stop voltage levels. These include 50%–50%, 20%–80%, 80%–20%, 10%–90%,
and 90%–10% which are automatically calculated for the user only after the Pulse Find has been initiated
by pressing the FUNC push button. User voltage settings can also be entered by changing the voltage
settings for the Start and Stop reference voltages manually, in Menu #2. When taking a single channel
measurement (TT+, TT-, PW+, PW-, PER and FREQ), the user is able to select either Channel 1 or 2 for
the measurement.
20 | Section 2 | Operation
Each measurement function has its own default setup for voltage settings, channel selection, level percentages,
and forced measurement modes. If for some reason these measurement setups need to be changed for a specific
application, the new setup becomes the default setup for that function.
The reference voltage level is also set on a channel-by-channel basis. This means that the user can have
different reference levels for each channel of the same function, such as Period or Pulse Width, etc. Toggling
between channels will change the reference trip point for the channel.
MENU #2: Channel Voltage References
CHAN 1 START VREF
CHAN 2 STOP VREF
+ 0.0000v
+ 0.0000v
Provides for the selection of voltage trip levels for the Start and Stop. Also the rising/ falling edge to be used
for the measurement Start and Stop is selectable.
The Pulse Find feature can be used to eliminate the need to set the trip reference voltage. This feature finds the
percentage of the input signals on Channel 1 and 2 and set the Start and Stop voltage reference to these values.
The voltage limits of the DTS are ±1.11 volts.
With the cursor positioned in this menu, pressing the FUNCTION button will initiate a pulse find.
See Section 2.2-5, Pulse Find, for more information.
MENU #3: EXTERNAL ARMING VOLTAGE REFERENCES
1
EXTERNAL ARM
2
GATE
+0.0000v
VREF
+0.0000v
Off H
Provide for the selection of voltage trip levels for the arming inputs. The rising/falling edge can also be set
for the arming inputs. The Pulse Find feature can be used to eliminate the need of setting the arming channel
voltage references if the 50% of peak to peak is the desired voltage.
Pulse Find will only search for the arming inputs if the trigger source (auto/external) is in external. Pulse
Find will also only find the arming input value if that arming input is selected in Menu #4, Select External Arm.
The voltage limits of the DTS are ±1.1 volts. See Section 2.2-5, Pulse Find, for more information.
Provides for the selection of External Arm 2 to be a level sensitive GATE. A selection of ON or OFF will
select gating.
The External Arm voltage reference input is used to select the direction and level of the gating. The operator
can select H (high) or L (low) which is the same as changing the External Arm 2 edge. See Section 2.5-8,
Gating, for more information.
Section 2 | Operation | 21
22
8
7
6
5
4
3
2
1
MEAS: 1ps
VREF
+0.0000v
+0.0000v
2
V LEVEL
+2.499999999999
+2.499999999999
Off
FILTER
000025.000ns +0.0000v
-LOWER LIMIT-
1
SELECT: CH 1
DELAY
STOP: 000002
- UPPER LIMIT-
CH
STROBE: ARM
START: 000001
SELECT ARM ON EVENT
Arm On Stop
Off H
GATE
STOP: Arm 1
SELECT ARM SEQUENCE
START: Arm 1
SELECT EXTERNAL ARM
EXTERNAL ARM
+ 0.0000v
+ 0.0000v
1
CHAN 2 STOP VREF
CHAN 1 START VREF
TR: 50% - 50% CH: 1-2 PK = ¦ 1.73ps JT = 2.57ps
FCN: TPD++
16
15
14
13
12
11
10
9
Save 1
Duty:
+0.0000
/ 00001000
+0.0000
MAX CHAN1 MIN
1,000,000
Save 4
0001
Ready
MN=
MX=
+0.0000
+0.0000
MAX CHAN2 MIN
Autoscale
DISPLAYED UNITS
Statistics
SIZE -- SAMPLE -- SETS
Off
Save 3
CLEAR
PRINT SELECT STATUS
Save 2
SCSI
0000000000
Off
MEASURE
ADDR = 05
Recall SETUPS
Peak
WAVEFORM
AUTO LOG
Setup
ADDR = 05
IEEE-488
SERIAL NUMBER: ¦
PART NUMBER:
DLY =
CABLE LENGTH MEASUREMENT
Figure 2.5 Menu Selections
Time Filtering
(Press Func to execute DC
measure or strobing)
Voltage
Measurement
Parameters
Arm on nth Event
Arming Sequence
Selection
Time Measurement
Parameters
Press Func for Pulse Find
Press Func for Pulse Find
Main Function
Statistics II
(Press Func to display
unfiltered values)
Statistics I
(Press Func for Pulse Find)
Pulse Find Peaks
Statistics Settings
(Press Func to execute)
Printer
(Press Func to RECALL/
SAVE on selected setup)
Memory
(Press Func to execute
when Clear selected)
Port Addresses/
Pulse Finder Mode
Assign part and
serial numbers
Cable Measurement
MENU #4: EXTERNAL ARMING SELECTION
SELECT EXTERNAL ARM
START: Arm 1
STOP: Arm 1
Select which arming input is used to arm the Start event and arm the Stop event. The DTS has two (2) arming
inputs, ARM1 and ARM2. See Section 2.5, Arming, for more information.
MENU #5: ARMING SEQUENCE SELECTION
SELECT ARM SEQUENCE
Arm On Stop
Selects the arming sequence to use in making a measurement. In the DTS, the arming sequence is selectable
with the trigger source either automatic or external.
There are three (3) sequence modes:
Arm On Stop
Arm On Start
Arm Start First
See Section 2.5, Arming, for more information
CH 1
Start Path
CH 2
Stop Path
Arm on Stop
Figure 2-6 Arm on STOP and START
Section 2 | Operation | 23
MENU #6: ARMING EVENT SETTING
SELECT ARM ON EVENT
START: 000001
STOP: 000002
Selects the Start or Stop event arm on nth event. The range is 1 to 131,071. This feature can be used to select
the number of edges or pulses to skip before starting or stopping a measurement.
See Section 2.5, Arming Selections for more information.
MENU #7: VOLTAGE MEASUREMENT - DC AND STROBED
STROBE ARM
CH
SELECT: CH 1
1
DELAY
V LEVEL
000025.000ns +0.0000v
Performs voltage measurement from the front panel.
Strobe Arm Select - Selects whether a DC or strobed voltage measurement will be performed.
Five (5) selections can be made:
DC - Measure the DC voltage on channel selected.
ARM1 - Measure the strobed DC voltage on selected channel at delay from selected arming
point using ARM1 input.
ARM2 - Measure the strobed DC voltage on selected channel at delay from selected arming point
using ARM2 input.
CH 1 or 2- Select input channel for DC or strobed voltage measurement.
Delay - Sets the delay from the arming trip point to the strobed measurement.
VLevel - Displays the measured voltage.
With the cursor in this menu, pressing the FUNC button will initiate a voltage measurement.
24 | Section 2 | Operation
MENU #8: TIME FILTERING
- UPPER LIMIT-
-LOWER LIMIT-
FILTER
+2.499999999999
+2.499999999999
Off
The DTS performs a digital band pass filter function.
This menu permits selection of upper and lower limits of values to be used in measurement calculations. Any readings
outside these limits are discarded.
Both the upper and lower limit may be selected from -2.5 sec to +2.5 sec, but the upper limit setting must be greater
than the lower limit setting. The DTS will not allow the user to violate this from the front panel. When entering the
upper limit first, always keep the values in the upper limit greater than the lower limit. Enter the lower limit second.
The maximum sample size allowed with filter enabled is 8,000. If the sample size is greater than 8,000 and the filter
function has been set to ON, the system sets the sample size to 8000.
One of the features of the time measurement used in the DTS is that the DTS will measure all of the pulses with respect
to one of its inputs, depending on which measurement mode is selected. For example, if TPD++ is selected and there are
10 pulses on Channel 2 for one on Channel 1, and if Arm on Stop is selected, and if a Burst of 1,000 is selected, then the
DTS will measure the TPD++ for each edge on the Channel 2 with respect to the one on the Channel 1. Then 100
measurements will be made for each TPD++ measured. Refer to START/STOP example below and the representation in
Figure 2-7.
(burst ÷ number of pulses = count/TPD) or (1,000 ÷ 10 = 100)
The band pass filter is used to select only the desired TPD you want displayed (Figure 2-7). Notice that all the data is in
the memory and each measurement can be read over the GPIB and the distribution for each of the 10 TPDs calculated
off-line by an external processor.
TPD
TPD
TPD
TPD
Figure 2-7 Band Pass Filter
Filter Theory
The user should understand the way measurements are taken when Filter = On. First, the data for the sample is collected
and each individual time is computed. Second, any values outside the limits are discarded. Third, statistics are calculated
based on the reduced number of readings.
When Filter = On, the average, standard deviation, and range does not include the readings outside the limits. The number
of readings displayed in the statistics menus will be the number of readings that were within the limits. Minimum and
maximum also reflects the readings inside the limits.
If Filter = On and no readings were within the limits, the sample completed number will be 0. The standard deviation
jitter will read -999,999,999 seconds and the message displayed will be:
NO VALUES IN RANGE
Section 2 | Operation | 25
MENU #9: CABLE MEASUREMENT
CABLE LENGTH MEASUREMENT
DLY =
MEASURE
Off
This menu allows the measurement of a cable to obtain its electrical length. The cables must be a 50Ω coax cable.
The procedure for measuring a cable is as follows:
Note: When measure is turned ‘on’ the hardware turns on a 1MHz sq. wave pulse at the Cal 1 & 2 outputs.
If desired, the user can use any frequency of signal as long as it is ‘0’ crossing and its period is longer
than the electrical length of the coax being measured.
1. Connect the “Cal 2” to the Channel 2 with a short length of 50Ω coax.
2. Connect the “Cal 1” to the Channel 1 with the cable measurement fixture to be used to measure all
subsequent 50Ω cables.
3. Enable the cable measurement mode by selecting ON in the menu.
4. Press the BURST push button.
The DTS will briefly display the following message:
SUBSEQUENT CABLES WILL USE THIS CABLE
ARRANGEMENT AS A REFERENCE.
Note: This means that the DTS “zeroed out” the particular cable arrangement just measured. To verify this,
press BURST a second time. The value read should be close to zero picoseconds.
5. Open the connector connecting the CAL 1 to Channel 1 and insert the cable to be measured.
6. Press the CONT or BURST push button.
The observed time is the electrical length of the cable being measured.
Note: Cable length measurement changes the front panel setup. It changes the forced measurement mode to
“Auto Arm on Start”, function to TPD++, START, STOP voltages to “0” volts.
Note: A signal validity check is made at the startup of cable measurement. A check that the signal is greater
than 30 millivolts is made and if not, a message is displayed:
SIGNAL LESS THAN 30 mV AMPLITUDE
CABLE MEASUREMENT FAILED
MENU #10: PART/SERIAL NUMBER
PART NUMBER:
SERIAL NUMBER: ¦
0000000000
This menu gives the user the means of recording individual device part numbers and serial numbers. The part
and serial numbers will accompany printed statistical data when using Printer Menu #13. An auto increment
feature is provided to increment or decrement the serial number.
26 | Section 2 | Operation
MENU #11: PORT
IEEE-488
WAVEFORM
ADDR = 05
Peak
SCSI
ADDR = 05
CLEAR
IEEE-488: Provide access for setting the IEEE-488 bus address from 1 to 31.
The default address setting from the factory is 05. To change the default setting to another address:
1.
2.
3.
Change the address to a new address using the Menu and Increment buttons.
Power down the instrument.
On successive Power-ups, the new address will be the default.
WAVEFORM: The Waveform selection of Peak or Flat directs the pulse find search and setting of the
reference voltages. With Peak selected, pulse find will search for the peaks and with Flat selected,
it will search for the major flat area of a waveform at the trailing edges of the waveform.
Note: See Section 2.2-5 for more information on Pulse Find.
SCSI: Allows the setting of the SCSI bus address from 1 to 7 hexadecimal.
The default address setting from the factory is 05. To change the default setting to another address:
1.
2.
3.
Change the address to a new address using the Menu and Increment buttons..
Power down the instrument.
On successive Power ON’s, the new address will be the default.
CLEAR: The CLEAR will cause the instrument to reset to the parameters of function TPD++. The front panel will display
the PORT menu with the cursor in the ADDR field. Sample size and sets size will be initialized to 1000.
MENU #12: MEMORY - NAME/SAVE/RECALL
Recall SETUPS
Setup
Save 1
Save 2
Save 3
Save 4
This menu is really three (3) menus in one (1). Place the cursor on Recall, the default selection, use the increment/
decrement buttons to move from Recall to NAME or Save.
There are ten (10) memories available for saving and recalling setups. The names of each memory can be changed using
any combination of A-Z and 0-9. To Save or Recall, select the respective submenu and place the cursor on the name and
press the Function button.
The names and information stored is not changed on a power down or clear. The information can only be changed by
the operator through the front panel or a host interface.
During a Save or Recall, the following parameters are saved for later recall, or recalled and used as DTS parameters:
Function Selection (defines edge direction)
Channel selection (Ch1/Ch2/Both)
Arming event arming sequence
Start reference voltage
Stop reference voltage
External Arm reference voltage
External Arm edge direction
Pulse find levels (percentages)
Start/Stop edge (rising or falling)
Sample size
Note:
Sets size
Start/Stop VOH (max peak) voltage
Start/Stop VOL (min peak) voltage
Filter On/Off
Filter minimum
Filter maximum
Start/Stop Arm on Nth count
Gating on/off
Start/Stop external arming inputs
Arming source
Strobe start point
Strobe stop point
Strobe increment value
Strobe number of points
Strobe arming channel
Strobe input channel
Strobe delay
DC channel
Cable measurement mode (on/off) not stored.
Parameters listed under Function Selection are saved for each function type.
External calibration values are not stored.
Section 2 | Operation | 27
MENU #13: PRINTER
AUTO LOG
Off
PRINT SELECT STATUS
Statistics
Ready
This menu allows the controlling of selected printouts. The printer supported is the Epson FX series of printers
emulating these basic features. Many modern printers support the basic features, but the operator might have to
manually select the mode.
Example: HP LaserJet II
1. Place printer OFF LINE.
2. Press MENU until FONT SRC appears on the first line of display.
3. Press +/- to select I (for internal fonts).
4. Press ENTER to save selection.
5. Press MENU to display FONT NUM.
6. Press +/- until font I018 is selected.
7. Press ENTER to save selection.
8. Press ON LINE to exit menu and place printer back on line.
The printer should now be ready for printout from the DTS. Similar types of setup to an IBM PC style of printer
may have to be performed to select font styles:
ABCDEfghijíó
#>@ˆ`{|
AUTO LOG - Directs the DTS to print out the statistics after each measurement.
Function
Measured
Maximum
Minimum
Range
Jitter
Period CH1 ........5,028.266ps......... 5,066ps ......... 5,006ps .......... 29.91ps ...........16.54ps
Period CH1 ........5,027.826ps......... 5,065ps ......... 5,002ps .......... 31.13ps ...........16.53ps
Period CH1 ........5,027.364ps......... 5,067ps ......... 5,002ps .......... 32.04ps ...........16.48ps
Period CH1 ........5,027.432ps......... 5,065ps ......... 5,004ps .......... 30.21ps ...........16.33ps
Period CH1 ........5,026.654ps......... 5,065ps ......... 5,003ps .......... 31.13ps ...........16.06ps
Period CH1 ........5,027.637ps......... 5,066ps ......... 5,004ps .......... 31.13ps ...........17.19ps
Period CH1 ........5,028.310ps......... 5,069ps ......... 5,001ps .......... 34.18ps ...........17.64ps
Period CH1 ........5,027.482ps......... 5,068ps ......... 5,004ps .......... 31.74ps ...........17.20ps
PRINT SELECT - Allows the selection of three (3) printouts when the ‘FUNC’ key is pushed:
1. STATISTICS - Statistics and instrument parameter used for those setups.
2. SETUP - Current instrument setup.
3. HISTOGRAM - Histogram of last measurement.
28 | Section 2 | Operation
STATISTICS Example:
Current Test Configuration
Measurement mode
Samples
Triggering
Gating with ARM2
User trip levels
Trip levels
Event sequence
Start arming cnt
Stop arming cnt
Filtering
:
:
:
:
:
:
:
:
:
:
Period Ch1
1001
Automatic
Disabled
Disabled
50% - 50%
Auto arm on stop
1
2
Disabled
:
:
:
+0.0004
+0.0004
+0.9617
:
:
:
:
:
:
:
1001
1
5,027.569 ps
5,067 ps
5,005 ps
30.52 ps
16.38 ps
:
:
:
:
:
:
:
:
:
:
:
:
:
:
Period Ch1
1001
Automatic
1
1
Disabled
Disabled
Auto arm on stop
1
2
Disabled
+2.499999999999
-2.499999999999
5
:
:
:
:
:
:
:
:
+0.0004
+0.0004
+0.0000 Rising
+0.0000 Rising
+0.9617
-0.9610
+0.0000
+0.0000
+0.0000
+0.0000
+0.0000
+0.0000
Trip Voltages
Start event
Stop event
Ch1 peak voltages
-0.9610
Test Results
Samples
Sets
Measured
Maximum
Minimum
Range
Jitter
SETUP Example:
Complete Setup
Measurement mode
Samples
Triggering
Start arming
Stop arming
Gating with ARM2
User trip levels
Event sequence
Start arming cnt
Stop arming cnt
Filtering
Filter maximum
Filter minimum
GPIB address
Trip Voltages
Start event
Stop event
Arm 1 trip level
Arm 2 trip level
Ch1 peak voltages
Ch2 peak voltages
Arm1 peak voltages
Arm2 peak voltages
Section 2 | Operation | 29
Measurement Mode: Period
CH1
Test Results
Samples
Sets
Measured
Maximum
Minimum
Range
Jitter
:1000
:1
:5,001.204ps
:5020ps
:4982ps
:18.62ps
:6.484ps
Figure 2-8 Histogram of Samples
30 | Section 2 | Operation
MENU #14: STATISTICS SETTING - Size & Format
SIZE -- SAMPLE -- SETS
0000100
DISPLAYED UNITS
0001
Autoscale
SAMPLE SIZE - Selects the number of measurements taken (1 to 1,000,000) for each burst used to
generate statistics.
SAMPLE SETS - Selects the count of a set of measurements used to generate statistics. The default set is 1.
Sample set and size work together to provide the number of measurements in a burst.
Example 1: Size = 1000
sets = 1
One (1) burst of 1000 measurements is taken
Example 2: Size = 1000
sets = 10
One thousand (1000) bursts of size ten (10) measurements are taken. Statistics for
each set (10) are generated and these statistics are used to generate the final
statistics which are displayed on the front panel.
DISPLAYED UNITS - Units to be displayed is selectable from seconds (s), milliseconds (ms), microseconds
VSLFRVHFRQGVSVDQGIHPWRVHFRQGVIV,Q$XWRVFDOH$7WKe display will start
up to nine (9) digits before shifting to the next wait of measurement in groups of three
(3) digits or scientific engineering notation.
MENU #15: PULSE FIND PEAKS
MAX CHAN1 MIN
MAX CHAN2 MIN
+0.0000
+0.0000
+0.0000
+0.0000
Displays the peak or flat level, determined by the waveform selection on Menu #11, of the input channel
reference voltages. See Section 2.2-5, Pulse Find, for more information.
With the cursor in this menu and the FUNCTION button pressed, the minimum and maximum voltages of
the input signal will be found.
MENU #16: STATISTICS I – Min/Max & Samples Taken
/ 00001000
Duty :
MX=
MN=
Samples Completed/Samples Size - The current number of measurements taken and the sample size are
displayed. The current samples completed are updated approximately
every one (1) second.
MX & MN - At the completion of a burst, the minimum and maximum values are displayed in this menu.
The displayed units are selected in Menu #14.
MX = Maximum value read
MN = Minimum value read
DC = Duty cycle is a percentage of the PW+ over Period, divided by 100
Section 2 | Operation | 31
2.4
MODE SELECTIONS
There are five hardware modes on the DTS:
Internal Calibration – Used to calibrate the internal circuits
External Calibration – Used to calibrate/deskew inputs
Burst – Used to take one set of readings equal to the Sample Size
Continuous – Used to take multiple sets of readings equal to the Sample Size
Idle – A wait state usually encountered after a Burst is completed or when instrument is Powered-Up.
2.4-1 INTERNAL CALIBRATION (Labeled INT CAL)
The DTS requires a minimum warm-up period of 30 min. for measurements and distributions to be within specification.
To initialize the internal calibration sequence after the recommended warm-up period, push the INT CAL button on the
front panel and a message will be displayed:
INTERNAL CALIBRATION
PRESS GO WITHIN 5s TO CONTINUE
If the user does not respond within 5 seconds the internal calculation will not be done.
When the GO button is pressed, a message will be displayed:
INTERNAL CALIBRATION 660 SECONDS TO GO
This indicates the amount of time remaining to accomplish all of the internal calibration procedures. The calibration
process is uninterruptable once the INT CAL switch is activated. The display will begin counting down from 660 sec.
When the countdown reaches 0 sec., the display will change to:
CALIBRATED
The previous mode and display then returns.
If a power loss occurs during the calibration and prevents its completion, the DTS will not complete the calibration and
will not change current calibration tables
2.4-2 INTERNAL CALIBRATION OPTIMIZATION
Internal calibration should be performed after the DTS has been powered-on for at least 30 minutes in a temperaturestable environment. The calibration is valid for varying time periods, depending on the operating environment. The
most important factor necessitating a re-calibration is a temperature change greater than published specifications. The
DTS ±25ps single shot accuracy depends on a recent calibration and temperature drift of less than ±5°C.
An external calibration should be performed after each internal calibration (See Section 2.4-3, External Calibration).
Internal calibration can be manually initiated at any time, without disconnecting external fixtures.
Extended Internal Calibration allows the user to reduce jitter due to the noise floor of the instrument through
the use of longer internal calibration periods. The selected multiplier, from 1 to 25, extends the base calibration period
of approximately 5.5 minutes by that factor. The table below shows typical results using the selected multipliers.
Calibration times are approximate.
Multiplier
Factor
1
2
6
24
32 | Section 2 | Operation
Cal
1-sigma
Time
jitter
5.5 min.
3.36
11 min.
2.56
33 min.
2.24
132 min.
2.19
0db Peak
Noise Floor
2.68ps
1.46ps
849fs
827fs
*** Embedded code version 1.98 or
greater must be installed for extended
internal calibration to work.
*** The extended internal calibration can
only be initiated via GPIB commands
with a user program or Virtual
Instruments™ version 3.20 or greater.
See Section 3 or the GPIB Programming
Guide for the command structure.
2.4-3
EXTERNAL CALIBRATION (Labeled EXT CAL)
External calibration for cables or probes can be accomplished in the same manner. When probes are used, an
appropriate probe tip to SMA adapter should be installed at the CAL1 and CAL2 SMA connectors.
To initialize External Calibration, push the EXT CAL push-button. This will initiate the sequence for measuring
and compensating for cable length. The display will read:
EXTERNAL CALIBRATION
PRESS GO WITHIN 5s TO CONTINUE
If the user does not respond within 5 seconds, the external calibration will not be done.
When the GO button is pressed, the following message will be displayed:
PRESS GO WITHIN 5s TO PERFORM
DC CALIBRATION PHASE
If the user does not respond within 5 seconds, the DC calibration phase will not be done. Go to AC calibration.
2.4-4
EXTERNAL CALIBRATION THEORY OF OPERATION
The user should understand the basic purpose of external calibration. It establishes zero reference points so subsequent readings can relate to the same condition as the “zero” point. External calibration does not just measure the
difference in the lengths of the cables; the process calculates the delays all the way to the logic inside the DTS. Note
that there is a separate path for each of the 16 possible combinations of the rising and falling signals so 16 offsets are
calculated and saved. This makes it unnecessary to recalibrate if you do an external cal in rising/rising mode and then
change to falling/falling. However, if cabling is changed, one must recalibrate to obtain valid, absolute measurements.
The DTS uses a zero-crossing 200MHz sine wave with a harmonic content of less than -50db. The references are set
to zero (0.000) volts during this calibration, and the input termination is set to GND.
After external calibration is complete, a quick check of the effectiveness of the calibration can be made by changing all
voltage references on the Start and Stop channels to 0.000 volts. Scroll through the measurement options and record the
measurement values for each option. Cross cable connections at Cal signal connectors. Scroll through the measurement
options again, and record their measurement values for each option. The average of the two measurements for each
option should be as follows:
1)
2)
3)
4)
TPD++, TPD--, TT+, TT-...................0ps ±10ps
PW+, PW-, TPD+-, TPD-+ ................2,500ps ±10ps
Period..................................................5,000ps ±10ps
Frequency............................................200MHz ±1kHz
Cable Length Restriction:
NOTE: Because of the 200MHz sine wave used for “EXT CAL”, the maximum cable length delta between CH1
and CH2 is 30.0cm.
2.4-5
DC CALIBRATION
When the GO button is pressed, the following messages will direct the user through the DC calibration:
APPLY SHORTING CAPS TO ALL INPUTS
PRESS GO
The shorting caps were shipped with the instrument and provide a ground to calibrate any offset from ground.
REMOVE SHORTING CAPS
PRESS GO
The DTS calibrates for any current compensation of the voltage divider network at the input of the A to D’s.
GROUND INPUTS FOR CH1 AND CH2
PRESS GO
Section 2 | Operation | 33
The DTS calibrates for any voltage reference difference caused by the probes being used between Channel 1 & 2.
DC CALIBRATION PHASE FINISHED
PRESS GO
2.4-6 AC CALIBRATION
CONNECT CH1 TO CAL1
CONNECT CH2 TO CAL2, PRESS GO
This message instructs the operator to connect the external cables or probes to be calibrated to the correct SMA
connectors. Once the connection is made, press GO and the instrument will automatically calibrate the cable
connected to CH1 and CH2. The LCD will then display the following:
CROSS CABLE CONNECTIONS AT
CAL SIGNAL CONNECTORS, PRESS GO
This message instructs the operator to connect the CH1 cable to CAL2 and CH2 cable to CAL1 (refer to NOTE
below). Once the connection is made, press GO and the instrument will automatically calibrate the cable connected
to CH1 and CH2. The LCD will then display the following for two seconds:
CALIBRATED
The previous mode and display then returns.
The unit has calibrated for the difference in the cable length of the external probes and the software will maintain
“constants” and will use these numbers when calculating time measurements.
Pressing any other switch during calibration also causes the previous mode and display to return. Calibration
values are still defined as before.
NOTE: Crossing the cables allows the DTS to isolate and ignore skew due to the calibration source. The
point where the signals are switched during AC calibration becomes the "zero reference point."
Any skew due to differences between that point and the DTS is calibrated out. If it is known that
there is negligible skew in the 200MHz calibration signal at the desired zero reference point, it is
not necessary to cross the cables.
2.4-7 CALIBRATION VALIDITY CHECKS
Before starting the calibration, a check is made to ensure the signal has an amplitude greater than 100 millivolts. If
not, a message is displayed:
PULSE < 100mV
After each calibration measurement, the jitter of the measurement is checked for less than 100 picoseconds. If not, a
message is displayed:
JITTER > 100ps
At the end of the External Calibration, a check is made that the measurements were reasonable. If not, a message
is displayed:
CAL NOT GOOD
34 | Section 2 | Operation
2.4-8 BURST (Labeled BURST)
Pressing the BURST mode push-button causes the DTS to begin taking readings. The indicator light will stay lit
until this mode has been completed.
The number of readings taken (1 to 1,000,000) will correspond to the sample size selected. When BURST has
completed taking the number of readings equal to the sample size, the new computed data is displayed and stored.
It can be observed by using statistics menus. The BURST indicator is extinguished and the DTS returns to an
idle state.
A Burst of up to 32,768 measurements is stored in the DTS memory and can be read over the GPIB for special
processing. When the filter is “On”, up to 8000 measurements are stored and read over the GPIB.
If BURST is interrupted by pressing any other mode push-button, the most recent computed data is returned (any
unprocessed data is lost).
BURST must be pressed again to accept another set of samples.
2.4-9 SPECIAL CASE
If FILTER is enabled, and BURST has been completed, only the number of readings taken within the bounds of the
filter will be displayed.
For example, if 1,000 readings were requested and 10 readings were outside the bounds of the filter, 990 readings
would be displayed along with the computed data of the 990 readings.
If the Statistics I menu is being displayed, the computed data for all 1,000 readings can be updated and displayed by
pressing the FUNCTION button.
If a new BURST is initiated without pressing the FUNCTION button, the data for the 10 readings outside the filter
boundaries are lost.
2.4-10 CONTINUOUS (Labeled CONT)
When the CONTinuous mode push-button is pressed, the DTS will begin taking readings. The indicator light will stay
lit as long as the DTS is in CONTinuous mode.
The DTS continues reading until it has measured the number of pulses (1 to 1,000,000) that was entered through the
front panel.
After CONT has completed taking the readings equal to the sample size, the new computed data is stored and displayed.
The process begins again to collect a new series of measurements equal to the entered sample size.
If CONT is interrupted by pressing any other mode push-button, the most recent computed data is displayed.
If FILTER is enabled, only the number of readings taken within the bounds of the filter will be displayed. For example,
if 1,000 readings were requested and 10 readings were outside the bounds of the filter, 990 readings would be displayed
along with the computed data of the 990 readings. The data for the 10 readings outside the filter boundaries is lost.
2.4-11 IDLE
Idle is a default mode, since it merely represents a defaulted, or waiting, condition usually after a BURST has been
completed.
2.4-12 DC CALIBRATION REFERENCE VOLTAGES
Used for measuring 5vdc reference voltage. Voltage should not deviate more than 1mV from recorded voltage on
rear panel. If reference voltage does change more than 1mV, contact your representative for service.
Section 2 | Operation | 35
2.5
ARMING SELECTIONS
The user can select any one of three Arming modes via the GPIB or from the front panel. There is a separate button
on the front panel for each of the three Arming modes. When one of the buttons is pressed, a light on the button will
illuminate to indicate which mode is active.
2.5-1 ARMING SOURCE SELECTION
The user has the option of selecting one of three Arming sources on the DTS. The Arm push-buttons are located
immediately above the Arm SMA connection on the lower right of the front panel.
Automatic Arm
External Arm
Manual Arm
The Default Arm mode is “Auto Arm.”
2.5-2 AUTOMATIC ARM (Labeled AUTO)
Pressing the Automatic Arm push-button allows readings based on the edges of the CH1 and CH2 pulses. The DTS
collects the number of samples selected, computes statistics, and displays them in the Statistics I and Main Function
menus, #1 and #16.
Enable/Arm mode (Menu #5) allows selection of several measurement modes and should be referenced when using
Auto Arm. The DTS selects the last used enable mode when powered up.
The number of measurements corresponds to the displayed sample size. When measurements equal to the sample size
have been collected, computations are made and displayed.
If Burst mode is selected, no further pulses are accepted without initializing Burst mode again.
If Continuous mode is selected, a new series of measurements will begin immediately.
Pressing any other Arming function switch deactivates the Automatic Arm and extinguishes the AUTO indicator light.
2.5-3 EXTERNAL ARM (Labeled EXT)
Pressing the External Arm push-button allows an external signal source to arm the instrument. The operator selects a
voltage level between ±1.11V, using Menu #3.
Once armed, the DTS measures the next pulse to be presented, with one measurement collected each time EXT Arm
signal is received. In ‘Gate’ mode the DTS measures as long as gate is in selected mode.
The number of measurements corresponds to the sample size selected. When the number of measurements equal to
the sample size is collected, computations are made and displayed in the statistics menus.
If Burst mode is selected, no further pulses are accepted without initializing Burst Mode again.
The required External Arm signal is any pulse of a minimum duration of 1ns pulse width occurring 3ns before the
signal on the Ch1 or Ch2 inputs.
See Section 2.5-8 for using External Arm input as “Gate.”
2.5-4 MANUAL ARM (Labeled MAN)
Pressing the Manual Arm push-button allows the GO switch to arm the Time Measurement Unit. Once armed, the
DTS measures the next pulse to be presented. One measurement is taken each time GO is pressed. The MAN indicator
light stays lit until a complete set of readings is taken. The number of measurements corresponds to the displayed sample
size. When measurements equal to the sample size have been collected, computations are made and displayed in the
statistics menu.
If Burst mode is selected, no further pulses are accepted without initializing Burst mode again.
If Continuous mode is selected, a new series of measurements can begin immediately.
Pressing any other Arming function switch deactivates the Manual Arm and extinguishes the MAN indicator light.
36 | Section 2 | Operation
2.5-5 ARMING SEQUENCE (ENABLE) MODES
Enable modes are program selectable from the GPIB or from the front panel Menu #5. The purpose of the
enable modes is to help resolve potential ambiguous situations that can occur, especially when Auto Arming.
An ambiguous occurrence would be measuring negative time when you wanted to measure positive time even
though both measurements would be valid.
All of the enable modes work in conjunction with which Arming source the user selects, Auto arm, External
arm, or Manual arm. The sequence of events for taking a measurement:
Note: The following sequence of events describes how the hardware works. It is important to note that
each Function in the DTS has an Enable Mode associated with it. From the front panel or GPIB
host interface, always select the function before changing a parameter association with a specific
function, such as the enable mode.
1.
2.
3.
4.
The selected Arming source is satisfied.
The selected Enable mode condition is satisfied.
The selected Function criteria is satisfied.
The measurement is made.
In the simplest case if the user is “Auto Arming” and wants to measure the TPD++ skew between two pins
of an IC, the sequence of events would be:
1.
2.
3.
4.
Select “AutoArm”.
Select “Enable Arm on Stop”.
Select the Function TPD++.
Make the measurement by executing the “Burst” command.
Executing the above sequence will enable the DTS to automatically Arm itself whenever the “CPU ready” is
up. The DTS then looks for a Stop event to occur on the “Stop Path” and then starts the measurement on the
next pulse whether it be on the START or STOP paths. In the case of a TPD++ measurement, see Figure 2-9.
Ch 1
Start
Path
Ch 2
Stop
Path
1. "CPU Ready"
enables the Enable
mode in Step 2.
2. Auto Arm on Stop is selected
so first STOP pulse after "CPU
Ready" arms DTS.
3. The TPD++ event
will then be measured.
Figure 2-9 Arm on Stop
“Enable Stop after Start” or “Enable Start after Stop”
This enable mode was developed for the cases where the customer wants to measure a TPD event on random
data with respect to a clock signal without any special external arming. In this figure, the application is to
measure the clock (cp) setup time with respect to the data input. The DTS execution sequence would be:
1.
2.
3.
4.
Select Arming mode “Auto or Ext”.
Select “Enable start first”.
Select function to be measured, “TPD++” or “TPD-+”.
Execute measurement.
Section 2 | Operation | 37
In Figure 2-9, selecting enable mode “Enable Start First” would have also worked. This later mode assures
positive time measurements when there are random events occurring. Although, in the case of differential
output skew, measurements using “Arm on Stop” assures the ability to make positive time measurements.
Ch 1 Start
Path
Ch 2 Stop
Path
Measures TPD++
1. Measure slected TPD mode only after Start event occurs.
Figure 2-10 Arm Start First
This enable mode enables the DTS to ignore clock (cp) pulses on Channel 2 that do not occur directly after
the selected data pulse on Channel 1 (See Figure 2-10). As before, the measurement will be in positive time
because of the “Start first” mode. In fact, if no event occurs that meets the above selected criteria the DTS
will not make a measurement but instead will return a “No Pulse Found” message.
2.5-6 USING THE ARMING SOURCE AND SEQUENCE TOGETHER
Auto Arm
The Default ARM source for the DTS is Auto Arm. With the DTS, there is much the user can do
without using any of the synchronous arming modes.
For example, measuring jitter with any of the measurement Functions using Auto Arm enables a worse
case jitter measurement. By using Auto Arm the DTS asynchronously or randomly measures the selected
parameters. If a statistically large enough sample size was selected for the jitter measurement, the user can
be assured of catching most any randomly occurring event. These events would escape detection with a
DSO sampling scope or any other triggered instrument. Refer to :$9(&5(67 App. Note 112 on measuring
Jitter for more details.
Because the DTS “Enable Modes” use the actual channel inputs for stimulus, “External Arming” is not
necessary for most types of measurements. In fact the only time the user must use External Arm is when
he/she wants to synchronize the DTS measurement with a specific event in the data stream.
A case like this would be a random data stream or vector set from an ATE tester. The user may want to
make a measure 101,356 cycles into the vector set. The External Arm input would be used to enable the
DTS prior to the parameter the user wants to measure.
In cases where the signal input is reoccurring or is a repeating pattern, then the DTS does not need to be
Armed externally. In fact the main benefit of running the DTS in Auto mode is to catch the stray random
event that would escape the real time or sampling oscilloscope (See Figure 2-10).
In Figure 2-10, the user wanted to measure the function TPD++. The user also selected Auto Arm and Enable
on Stop. Figure 2-10 shows the sequence of events leading up to the actual measurement. If a Sample Size
count was set to some number like 1000 then the above cycle would repeat itself 999 more times.
The results of all 1000 one-shot measurements are stored in DTS memory and statistically analyzed to
display the AVERAGE, ± PEAK and RMS JITTER. The ± PEAK is the min/max spread of the
1000 measurements and represents the RMS jitter in a Gaussian distribution. The AVERAGE is the center
of the distribution.
38 | Section 2 | Operation
External Arm
Arming inputs 1 and 2 are multifunctional. The following are selectable via the GPIB or front panel Menus 3 & 4.
Menu 3:
1.
Enter the external voltage reference trip point for Arm 1 & 2. If “Pulse Find” is executed while the DTS
is in External Arm mode, the Arming trip point levels will automatically be found and entered into these
registers for the user. The value entered will be the 50% point of the arm channel.
2.
Select the edge direction of the external Arm signal to arm the channel inputs by changing the direction
of the rising/falling symbols in front of each reference voltage.
Menu 4:
1.
Select which Arm, 1 or 2, to arm Channel 1 or 2. Arm 1 or 2 can arm Channel 1 and 2 separately, or Arm 1
or 2 can arm both channels (See Figure 2-11).
Arm Start Path
3ns min.
Measure Function Period
Ch 1 or 2
Arm Stop Path
Ext Arm
1 or 2
Figure 2-11 External Arm
For example, both channel inputs 1 and 2 can be armed by the same arm signal. To do this, connect the desired
arming signal through a power splitter to both arming inputs, 1 and 2. The user could then choose to arm Channel 1
on the rising edge of the Arm 1 and Channel 2 on the falling edge of Arm 2. In that way the pulse width of the arming
signal controls the time duration between the measurement taken between Channels 1 and 2 or on the same channel
(See Figure 2-12).
Skip ’N’ Pulses
Ch 1 or 2
3ns min setup time
Ext Arm
1 and 2
Arm pulse width used as delay
Figure 2-12 External Arm With Delay
Manual Arm
In the Manual Arm mode, the DTS is armed by pushing the GO button on the front panel or via the GPIB in the same
manner. The DTS would work in the same manner as if it were in the External Arm mode, except the external arming
would be done manually instead of electrically.
This mode is useful when the user wants to synchronize the DTS with some experiment such as the turning on of a
power supply to look at the power up jitter of a PLL. This mode is also useful in setting up the DTS to wait for some
randomly occurring event that the user is trying to catch in one-shot mode.
Section 2 | Operation | 39
2.5-7 AMBIGUITY
Whenever the DTS is making a time measurement, it is possible to get the CH1 and CH2 pulses in either order.
It is important to know the DTS always measures and displays time as follows:
Positive Time T................Always when CH1 occurs before CH2
Negative Time -T.............Always when CH2 occurs before CH1
The fact that the DTS keeps track of which pulse comes first in a typical measurement and can give both a positive and
negative result can cause some concern and confusion when taking readings. The DTS, with its different arming
modes, minimizes the possibility of ambiguity, but the user should be fully aware of the DTS arming capabilities
to avoid potential ambiguous readings.
The DTS offers several different arming capabilities to solve ambiguity. It is possible, especially with the requirement
that the EXT Arm pulse be 3ns prior to the signals to be measured, that a confusing set of readings can happen. The
example in Figure 2-13 shows a proper setup that will not give any ambiguous reading. The following two examples
(Figures 2-13 and 2–14) help explain a situation that would result in ambiguity.
Example 1 - Proper Setup: (See Figure 2-13)
1) The DTS is in EXT Arm mode and is waiting to be armed by the external signal.
2) A test setup is configured such that the EXT Arm signal is placed 3ns in front of the CH1 and CH2 pulses
at the setup.
3) There are three cables for CH1, CH2, and EXT Arm to the DTS which are exactly the same length.
4) The time expected to be read is t, the propagation delay represented in the diagram between the two pulses,
one on CH1 and one on CH2.
5) The “System Arm” represents the EXT Arm signal as seen at the DTS.
In this example, since the cables are the same length, the System Arm at the DTS arrived at the proper time -3ns prior
to the two events to be measured.
t
System
Arm
t
System
Arm
START
STOP
Figure 2–13 Example 1 - Proper Readings
In this case, the expected results were obtained, which was to see t, a positive propagation delay between CH1 and CH2.
40 | Section 2 | Operation
Example 2 - External Arm Delayed: (See Figure 2-14)
1) The DTS is in EXT Arm mode and is waiting to be armed by the external signal.
2) A test setup is configured such that the EXT Arm signal is placed 3ns in front of the CH1 and CH2 pulses at the setup.
3) There are two cables for the CH1 and CH2 that are exactly the same length. The third cable for the EXT Arm is a
little longer than the other two cables.
4) The time expected to be read is t, the propagation delay represented in the diagram between the two pulses, one on
CH1; one on CH2.
5) The “System Arm” represents the EXT Arm signal as seen at the DTS.
Notice in this example that since the cable for the EXT Arm was a little longer, the System Arm signal seen at the DTS
arrived at the wrong time. In fact, it arrives later than the CH1 signal, but before the CH2 signal.
t
System
Arm
t
START
STOP
Figure 2–14 Example 2 - Arming Signal Delayed
In this case, the expected results were not obtained, which was to see t, a positive propagation delay between CH1 and
CH2. Instead, the DTS measured the time between the CH2 and CH1 and the result was a -t. This could be interpreted
as an ambiguity reading.
These examples are not to imply that every situation can be solved by using the right cable length but to merely point out
the potential ambiguity.
Example 3 - Positive and Negative Readings
1) The DTS is in EXT or AUTO Arm mode.
2) If in EXT Arm mode, a test setup is configured such that the EXT Arm signal is placed near the edge of the Arm
window shown in Figure 2-15.
3) If in AUTO Arm mode, signals are applied to the CH1 and/or CH2 inputs and the DTS is making measurements.
4) As an example, the DTS is measuring TPD++ using AUTO ARM ON STOP
The DTS arms the start and stop paths approximately 3ns after the rising edge of the signal on the CH2 input. Because
of jitter, this can cause a condition to occur where the CH1 signal is missed until the next pulse occurs. A negative
reading for t will occasionally result when this situation exists. One method of eliminating any negative readings is
to delay the CH1 signal a known value. If dealing with the average statistic, these readings are just part of the average.
Section 2 | Operation | 41
START
3ns
PW+
PW-
’t’
STOP
Figure 2-15 Example 3 - Getting Both Positive & Negative Readings
The potential for positive and negative readings increase with faster pulses because of signal jitter. The band pass
filter capability can be used to filter out undesired readings of a measurement.
2.5-8 GATING (USING ARM 2 INPUT)
The instrument can use the Arm 2 input as a “gate” of arming.
When External arming, the Arm 2 input on the front panel can be used as an EDGE sensitive ARMING input or
as a LEVEL sensitive GATE. In Menu #3, the user selects how Arm 2 input will be used (See Figure 2-16).
Ch 1/2
measurement
Ch 1/2
Ext 1
Gate 2
Figure 2-16 Gating Mode
The main difference between using Arm 2 input as a gate vs. edge sensitive is the DTS will make measurements
whenever the gate meets the user selected criteria, whereas, if Arm 2 is edge sensitive the DTS will only make a
measurement once for every edge of the arming signal. In Menu 3 the user can turn the gate “ON” or “OFF” and
select whether to arm the DTS when the gate is HIGH or LOW.
In Figure 2-16 the DTS was set up to make measurements based on the following criteria:
1.
2.
3.
4.
Is the Gate High?
Is the Arm 1 input going high?
Enable Stop after Start.
Make the selected measurement; Period in this case.
The GATING mode is useful if the device to be tested has a “ready or lock” signal such as when a PLL is locked
onto some serial pattern. For instance, the user may want to only measure the period when the PLL is locked and
the data is high and measure again when the PLL is not locked while the data is high to see the difference in
frequency and jitter.
42 | Section 2 | Operation
2.5-9 MEASURING VOLTAGE IN TIME (STROBING VOLTMETER)
The Delayed Scan mode enables the DTS to measure the voltage on either channel at a point in time determined by the
delay setting programmed into the DTS, with respect to the arming signal referenced (See Figure 2-17).
The point where the DTS strobe digitizes is determined by the position of the arming signal plus the delay value
programmed into the delay register in Menu #7. The user can position the arming edge and/or the delay value to set
the point where the DTS strobe digitizes.
Menu #7 gives the user the ability to select the STROBE arming, INPUT CHANNEL to be measured, and the DELAY
with respect to the Arming input selected. By pushing the FUNC key on the front panel while in Menu #7, the DTS will
measure the voltage point on the channel selected. The voltage is then displayed under VLEVEL.
1. STROBE INPUT: ........... DC, CH1, CH2, Arm1 or Arm2
2. CHANNEL: .................... 1 or 2
3. DELAY:.......................... 25ns to 100µseconds
“STROBE INPUT” can be either DC, which means a 16 bit A/D converter will measure the average or steady state
voltage on the selected channel, or the user can select CH1, Ch2, Arm 1 or Arm 2 inputs to reference the programmed
delay value (See Figure 2-17).
The DTS uses a successive approximation technique in conjunction with the 150µV resolution voltage references at the
comparator inputs to find the voltage at the input channel at the end of the programmed delay period. The minimum
programmable delay is 25ns delayed from the selected slope of the Arming input referenced. See the DTS GPIB
Programming Guide for details on the programming and use of the Delayed Scan Mode.
Start
Scan
Stop
Scan
Ch. 1 or 2
Min.
Delay
ARM1 or 2
Window scan input channel.
Figure 2-17 Delayed Scan for Measuring Voltage in Time
If a “WINDOW” measure is executed over the GPIB, several statistical parameters are available, VAVERAGE,
VMINIMUM, VMAXIMUM, VDEVIATION and VDATA. For example, VDATA is a string of all of the voltage
data points taken in the WINDOW search. The user can choose to display these parameters graphically to show the
actual waveform on the channel or select one of the other parameters for a quick quantitative analysis.
In Figure 2-17, the signal on either of the DTS channels can be WINDOW scanned and the VDATA read to a PC or
workstation and then processed or displayed much as an oscilloscope would. In this case the DTS Arming input
selected would operate much like an oscilloscope trigger.
Section 2 | Operation | 43
2.6
STATISTICAL CALCULATIONS
The number of individual readings used to produce the statistics is determined by the settings of the sample
and set size in Menu 14.
Sample Size
The usual number of measurements taken is simply the sample size. In this mode the sets size is one (1) and
the sample size is some number between one (1) and one million (1,000,000).
In practice we recommend a sample size somewhere between fifty (50) and five hundred (500). Any fewer
than this will not run much faster and little more accuracy is gained with more than this.
Some special cases of sample size settings are:
Filtering - The maximum number of readings that can be filtered is eight thousand (8000). If the sample
size is set to greater than 8000 and the filtering is on, the instrument will take only 8000.
Cable Measurement - The minimum sample size of a cable measurement is five hundred (500).
Set Size
The set size can be used to measure the standard deviation of a set of measurements.
In this mode the instrument will take a measurement of set size, create statistics, and repeat this the number
of sample size times.
An example with a set size of 100 and a sample size of 1000, the instrument would take data from 1000
measurements of size 100. The statistics created and displayed would be generated from the statistics of
the 1000 sets of measurements.
This would typically show the standard deviation of a group of measurements over time which would be lower.
Statistics
The computation of statistics is straight forward.
Average is the sum of all individual readings divided by the sample size (assuming set size = 1).
Minimum is the algebraically smallest reading.
Maximum is the algebraically largest reading.
± Range is the (maximum - minimum/2).
Standard deviation is the square root of the sum of the squares of the difference between successive
individual readings and the average, divided by n-1, where n is the sample size.
The exception to this is when filtering is On. The sample size, for calculation of statistics, is the number of readings
within the filter range. The Statistics I menu, #16, indicates the sample completed in the filter range. Pressing the
Function button when on the Statistics I menu, #16, will display the unfiltered statistics of the last measurement.
2.7
INSTALLATION AND MAINTENANCE
The DTS is typically installed in a stand-alone or benchtop configuration. Optional accessories are available to
install the DTS in a rack mount configuration. Installation instructions for rack mounting are included with the rack
mounting kits.
This equipment is intended to be connected to supply mains with the power cord provided with the product. Transient
overvoltages are to be less than limits defined by installation category II, Annex J of EN 61010-1.
2.7-1 INSTALLATION LOCATION
The DTS should be installed in a clean, temperature stable environment. Although the operation temperature ranges
is 15°C to 35°C, the ambient temperature must be maintained within ±5°C to stay within calibration specifications.
The DTS should be installed in an area that allows unobstructed airflow of at least two inches on each side for
ventilation, and appropriate spacing in the front and back for cable routing.
The IEC plug on the AC power cord acts as the safety disconnect for the DTS. Whenever possible, always install the
DTS such that easy access is provided to the safety disconnect.
44 | Section 2 | Operation
2.7-2 MOUNTING
In the bench-top installation, the DTS should be mounted on a surface capable of carrying at least 80 pounds. When
mounted on a portable cart, such as a scope cart, the DTS can be secured with straps for added safety.
In the rack mount configuration, the DTS feet sit in detents on the mounting shelf preventing the unit from sliding. In
addition, mounting brackets allow the DTS to be attached to the 19-inch equipment frame. The weight is carried by
the rack mount shelf. (Detailed mounting instructions are provided with the rack mounting kit.)
2.7-3 VENTILATION
To provide adequate ventilation for the DTS, a minimum of two inches of unobstructed air flow must be maintained
on each side of the DTS. To maintain the highest accuracy, the DTS air intake should not be near sources that
would cause ambient temperature fluctuations. Temperature fluctuations greater than 5°C would require the DTS to
be re-calibrated.
2.7-4 MAINTAINING PROPER INSTRUMENT GROUNDING
Both 120VAC and 230VAC power sources require an earth ground at the power connection. Failure to provide this
safety ground could result in improper measurements and/or electrical shock danger to the operator.
Only qualified service personnel should perform maintenance procedures on the DTS. When maintenance is
performed, NO protective earth ground connections should be removed.
NOTE: Where this product is installed at areas requiring main power connections other than the three-pronged North
American power plug, the main power cord must be replaced with the cord and plug appropriate to the location. The
main supply cord must be rated to meet or exceed the current rating on the IEC connector (10 amps) and must meet the
requirements of H05VV power cords in IEC 227 or IEC 245. If the appropriate power cord cannot be obtained locally,
contact the :$9(&5(67 Corporation factory and one will be provided.
2.7-5 FUSE REPLACEMENT
The IEC plug-in at the back of the DTS provides the input connection for the AC power cord. A small compartment
on the IEC plug houses two 6.3AT/250V fuses (5x20mm). The manufacturer’s part number is Wickmann 19195-066.
To gain access to the fuses, remove the power to the DTS and disconnect the power cord. With a small screw driver,
pry open the fuse compartment on the IEC plug. Remove the fuses and install the new fuses prior to closing the
compartment and reinstalling the power cord.
2.7-6 PREVENTATIVE MAINTENANCE
There are no user required preventative maintenance requirements recommended other than annual calibrations to
NIST standards and routine cleaning of the exterior with a clean, damp cloth. Annual calibrations may be performed
by a qualified calibration laboratory or at the :$9(&5(67 factory in Eden Prairie, MN.
2.7-7 INTENDED USE OF EQUIPMENT
The DTS unit weight is approximately 40 pounds. To avoid injury or damage to the unit, the DTS should be carried
and installed by two people.
The DTS should be used only for its intended purpose as outlined in this manual. To avoid possible injury, the DTS
should not be operated with the top cover or other panels removed. Refer installation and maintenance to qualified
service personnel.
To avoid explosion, do not operate the DTS in or near an atmosphere of explosive gases
It is essential to maintain the protective earth ground through the grounding connector of the power cord. A loss of
the protective ground can cause electrical shock.
Section 2 | Operation | 45
OPERATOR’S QUICK REFERENCE TABLE
FRONT PANEL SWITCHES/INDICATORS
Switch/Indicator
Indicator ON
Function
Power ON/OFF
Power ON
Toggles Power On/Off.
INT CAL
Internal Calibrate activated
Automatically calibrates DTS.
EXT CAL
External Calibrate activated
Calibrates/Inputs Deskew.
BURST
Burst mode activated
Takes readings according to the setting
of Sample Size display. Then stops.
CONT
Continuous mode activated
Takes readings according to the setting
of Sample Size display. Then continues
to update readings and display.
MAN
Manual arm activated
Arm the DTS for measuring the
next pulse presented.
AUTO
Automatic arm activated
Allows automatic sample collection
with arming from a channel input.
EXT
External arm activated
Allows external signal to arm the DTS
for measuring the next pulse presented.
MENU SCROLL
Changes menus
Scrolls from menu to menu and field to
field inside a menu.
INCREMENT/
DECREMENT
Changes fields
Increase or decrease values in fields
or changes options.
GO
Starts DTS
Starts the DTS after required
external action taken by user.
FUNCTION
Pulse Find activated
Activates Pulse Find when pressed in
menu nos. 1,2,3 and 15. Updates filtered
statistics when in menu #16. Execute
clear in menu #11. Execute Save/Recall
in menu #12. Executes voltage measure
in menu #7.
Table 2-2 Operator’s Quick Reference Table
46 | Section 2 | Operation
SECTION 3 - GPIB INTERFACE
3.1
SUMMARY OF DTS COMMANDS
This section examines the layout of the syntax defined by IEEE-488.2. It consists of definitions and sub-definitions
for a “program message unit.”
In addition to the Common commands defined for all instruments by IEEE-488.2, the commands for the DTS are
organized into 8 different subsystem sets. They are:
System - Controls some basic function of the DTS.
Acquire - Provides access to the parameters for acquiring and storing data.
Calibrate - Provides the selection of different calibrate functions and retrieves data
generated by these functions.
Channel - Provides access to the parameters associated with the different channels.
Display - Provides access to the parameters for controlling how or what information will be
written to screen.
Measure - Selects the measurements to be made.
Trigger - Controls the trigger modes and parameters for each trigger mode.
Hardcopy - Controls printing of instrument configurations and measurement statistics.
3.1-1 SYSTEM COMMANDS
:SYSTem:ARMing< /trigger source/trigger sequence/start arm ................ Arming macro for speed.
/stop arm/arm 1 ref/arm 2 ref/arm 1 slope
/arm 2 slope/start count/stop count>
:SYSTem:CHANnel<1|2|BOTH> .............................................................. Set channel.
:SYSTem:CHANnel? ............................................................................... Read channel.
:SYSTem:DCCHANnel<1|2> ................................................................... Select dc measurement channel.
:SYSTem:DCCHANnel?.......................................................................... Read dc selected channel.
:SYSTem:ELAPsed/<OFF|ON> ............................................................... Select timed burst mode.
:SYSTem:ELAPsed? ............................................................................... Read current timed burst selection.
:SYSTem:EVENt/<OFF|ON>/<1|2>/<RISe|FALl> .................................... Select event mode.
:SYSTem:EVENt? .................................................................................... Read current event selection
:SYSTem:GATing<ON|OFF> ................................................................... Turn gating on or off.
:SYSTem:GATing? .................................................................................. Read gating selection.
:SYSTem:GO ............................................................................................ Execute GO button.
:SYSTem:NOGO ...................................................................................... Execute GO, but do not perform function.
:SYSTem:HEADer<OFF|ON> .................................................................. Select header type.
:SYSTem:HEADer? ................................................................................. Read header type selected.
:SYSTem:LONGform<OFF|ON> ............................................................. Select long or short form of headers.
:SYSTem:LONGform? ............................................................................ Read long or short-form selected.
:SYSTem:MACro/<function/channel/trigger source/trigger sequence ................... Macro used for speed.
/percent/start reference voltage/stop reference voltage>
:SYSTem:STAT/<AV><JI><MN><MX> ............................................... Selects sets of statistics to be saved.
:SYSTem:STAT?.............................................................................. Reads number of sets acquired
Section 3 | GPIB Interface | 47
:SYSTem:STRObeARM<CH1|CH2|ARM1|ARM2|DC><POS|NEG|RISe|FALl> ...................Select strobe arming input.
:SYSTem:STRObeARM? ......................................................................................Read strobe arming input.
:SYSTem:STRObeCAL..................................................................................Initiate a strobe calibration.
:SYSTem:STRObeCHANnel<1|2> .......................................................................Select strobe input channel.
:SYSTem:STRObeCHANnel?...............................................................................Read strobe channel.
:SYSTem:STRObeDELay<value> .........................................................................Set strobe delay.
:SYSTem:STRObeDELay? ...................................................................................Read strobe delay.
:SYSTem:STRObeINC<value> ..............................................................................Set step increments|value.
:SYSTem:STRObeINC? ........................................................................................Read step increments|value.
:SYSTem:STRObeLEVel/<1|2>/<ARM1|ARM2|CH1|CH2>/max start delay/max end ............ Set delays for strobe pulsefind.
delay/max delta/ min start delay/min end delay/min delta>
:SYSTem:STRObeSTARt<value> .........................................................................Set start delay.
:SYSTem:STRObeSTARt? ...................................................................................Read start delay.
:SYSTem:STRObeSTOP<value> ..........................................................................Set stop delay.
:SYSTem:STRObeSTOP? ....................................................................................Read stop delay.
:SYSTem:STRObe#<value> ...................................................................................Set number of steps.
:SYSTem:STRObe#? .............................................................................................Read number of steps.
:SYSTem:TIMEout<value> .....................................................................................Timeout on pulse measurement.
10 second default. Integer seconds.
:SYSTem:TIMEout? .......................................................................................Read timeout value.
:SYSTem:WAVe<PEAK|FLAT|STRObe> ................................................................Set pulse find to locate peaks or flat
spot (usually for a non-sine wave).
:SYSTem:WAVe? ...................................................................................................Read type of waveform search
to be used by pulsefind.
:SYSTem:WINDow</start value/stop value/<step increment#of steps> ...............Set parameters.
3.1-2
ACQUIRE COMMANDS
:ACQuire:ALL<TT+|TT-|PW+|PW-|PERiod|TPD++|TPD- -|TPD+-|TPD- +|FREQ> ....................Select function and return all statistics.
:ACQuire:ANALysisFUNCtion</Func/Chan/LowStartCount/HighStartCount .....................Select function/chan and return
/StopCountDesignator/Increment/DataDes>
function statistics
:ACQuire:ANALysisJITTer</Func/Chan/StartCount/LowStopCount .................................Select function/chan and
/HighStopCount/Increment/DataDes>
return jitter statistics.
:ACQuire:ANALysisRANGe</Func/Chan/StartCount/LowStopCount ...............................Select function/chan and
/HighStopCount/Increment/DataDes>
return (Max-Min)/2.
:ACQuire:COMPlete? .............................................................................................Number of readings taken.
:ACQuire:COUNt<value> .......................................................................................Set Sample Size.
:ACQuire:COUNt?...................................................................................................Read Sample Size.
:ACQuire:DUTY.......................................................................................................Returns duty cycle.
:ACQuire:FUNCtion<TT+|TT-|PW+|PW-|PERiod|TPD++|TPD- -|TPD+-|TPD-+|FREQ> ...........Select function.
:ACQuire:FUNCtion? ..............................................................................................Read function selected.
:ACQuire:LEVel .......................................................................................................Pulse Finder.
:ACQuire:MEASure.................................................................................................Takes a measurement and returns
average & standard deviation.
:ACQuire:RUN <TT+|TT-|PW+|PW-|PERiod|TPD++|TPD- -|TPD+-|TPD-+|FREQ> ...................Select function and return
average and jitter.
48 | Section 3 | GPIB Interface
:ACQuire:SETsCOUNt<value> ...........................................................................Set sets size.
:ACQuire:SETsCOUNt? .....................................................................................Read sets size.
:ACQuire:WINDow</start value/stop value/<step increment|#of points> ............Set parameters and return
voltage average.
3.1-3
CALIBRATE COMMANDS
:CALibrate:DATA<block>...................................................................................Set external calibration values.
:CALibrate:DATA? ..............................................................................................Read external calibration values.
:CALibrate:EXTernal...........................................................................................Initiate external calibration.
:CALibrate:INTernal ............................................................................................Initiate internal calibration.
:CALibrate:REF? .................................................................................................Return cal. reference voltage.
:CALibrate:SIGnal<“OFF, “8K,”1M”,”200M”> .......................................................Set internal calibration signal.
:CALibrate:SIGnal? .................................................................................... Read cal signal setting.
:CALibrate:XINTernal<ASCII value> ..................................................................Initiate extended internal calibration
:CALibrate:XINTernal? ............................................................................... Read extended internal cal value.
3.1-4
CHANNEL COMMANDS
:CHANnel<STARt|STOP>:EXTernalarm<ARM1|ARM2>..............................Select event external arm.
:CHANnel<STARt|STOP>:EXTernalarm?.......................................................Read selected external arm.
:CHANnel<STARt|STOP>:LEVel<value> ........................................................Set event trip level.
:CHANnel<STARt|STOP>:LEVel? ...................................................................Read event level.
:CHANnel<STARt|STOP>:<MIN|MAX>?.........................................................Read START or STOP min
or max peaks.
:CHANnel<STARt|STOP>:COUNt<1 to 131072> ..........................................Set event arm on Nth count.
:CHANnel<STARt|STOP>:COUNt? .................................................................Read event arm on Nth count.
:CHANnel<SWITchIDN? ............................................................................ Returns Version of DSM-16
:CHANnel<SWITch<NN> ........................................................................... Select DSM-16 chan. and switch
:CHANnel<SWITch?................................................................................... Returns selected chan. and switch
:CHANnel<SWITch<ON|OFF> ................................................................... Enables/disables DSM-16 front
panel switches.
3.1-5
DISPLAY COMMANDS
:DISPlay:FILTer<ON|OFF>..................................................................................Select filtering on or off.
:DISPlay:FILTer?.................................................................................................Read selected filtering.
:DISPlay:FILTer<MINimum|MAXimum><value> .............................................Set filter value.
:DISPlay:FILTer<MINimum|MAXimum>? .......................................................Read filter value.
:DISPlay:LEVel<value value> ..............................................................................Set percent.
:DISPlay:LEVel? ..................................................................................................Read pulse percent.
:DISPlay:LINE<quoted string>...........................................................................Display message on screen.
:DISPlay:PANel<ON|OFF> ................................................................................Turn front panel on or off.
:DISPlay:PANel? .................................................................................................Read panel mode.
:DISPlay:STATistics<ON|OFF>.........................................................................Turn update stats to display on / off.
:DISPlay:STATistics?..........................................................................................Read statistics mode.
:DISPlay:TEXTBLANk ........................................................................................Clear or restore display.
:DISPlay:USER<ON|OFF>.................................................................................Selects user reference voltages for
current function.
:DISPlay:USER?..................................................................................................Reads current user state.
Section 3 | GPIB Interface | 49
3.1-6
MEASURE COMMANDS
:MEASure:AVERage? ...................................................................... Read average.
:MEASure:DATA?............................................................................. Return measurement data.
:MEASure:DATA4? .................................................................... Return measurement data as floating point.
:MEASure:DATAT? .......................................................................... Return timed burst elapsed times.
:MEASure:DCvlevel?........................................................................ Read dc level.
:MEASure:EVENt?............................................................................ Returns event counter value (0-65536)
:MEASure:JITTer?............................................................................ Read jitter.
:MEASure:MIN? ................................................................................ Read minimum measured value.
:MEASure:MAX?............................................................................... Read maximum measured value.
:MEASure:RANGe?.......................................................................... Read range of measured values.
:MEASure:SDEViation? ................................................................... Read standard deviation.
:MEASure:STAT4? .......................................................................... Returns statistical data defined by :SYST:STAT
for number of samples as float
:MEASure:STRObeVLEVel?........................................................... Read strobed voltage level.
:MEASure:VMAXimum? .................................................................. Read strobed maximum voltage.
:MEASure:VMINimum?.................................................................... Read strobed minimum voltage.
:MEASure:VSDEViation?................................................................. Read voltage standard deviation.
:MEASure:VDATA? .......................................................................... Return strobed measured points.
:MEASure:VDATA4? ........................................................................ Return measurement data as floating point.
:MEASure:WINDow?........................................................................ Return average strobed voltage.
3.1-7
TRIGGER COMMANDS
:TRIGger:LEVel<ARM1|<ARM2|GATe><value> .......................... Set trigger level.
:TRIGger:LEVel<ARM1|<ARM2|GATe>? ..................................... Read trigger level setting.
:TRIGger:<MAX|MIN><ARM1|ARM2>.............................................. Read arming peaks.
:TRIGger:SEQuence<STARt|STOP|STARtFIRST>..................... Selects trigger sequence.
:TRIGger:SEQuence? ...................................................................... Reads trigger sequence.
:TRIGger:SLOPe<ARM1|<ARM2|GATe><POS ............................... Set arming direction.
|NEG|RISe|FALl|High|Low>
:TRIGger:SLOPe<ARM1|<ARM2|GATe>? ................................... Read arming direction.
:TRIGger:SOURce<EXTernal|AUTomatic|MANual> ................... Selects trigger source.
:TRIGger:SOURce?.......................................................................... Read trigger source.
3.1-8
HARDCOPY COMMANDS
:HARDcopy:HISTogram ................................................................... Print burst histogram.
:HARDcopy:PART<alpha-numeric> ............................................... Enter part number.
:HARDcopy:PART? .......................................................................... Return part number.
:HARDcopy:SERial<integer>...................................................... Enter serial number.
:HARDcopy:SERial?................................................................... Return serial number.
:HARDcopy:SERialDECRement ................................................ Decrease serial # by one.
:HARDcopy:SERialINCRement.................................................. Increase serial # by one.
:HARDcopy:SETup ........................................................................... Print DTS set-up.
:HARDcopy:STATistics .................................................................... Print statistics w/abbrev.
set-up information.
50 | Section 3 | GPIB Interface
3.2
IEEE-488.1 BUS COMMANDS (HARDWARE)
The following commands are IEEE-488.1 bus commands (hardware line ATN true).
Device Clear - The device clear (DCL) command causes the DTS to perform a warm boot.
Group Execute - Will cause the same action as the trigger (GET), RUN and *TRIG commands. The
DTS will acquire data.
Clear Interface (IFC) - Halts all bus activity.
3.2-1
COMMON COMMANDS
The following are common commands defined by IEEE-488.2 and supported by the DTS.
*CLS ............... Clear Status
*ESE ............... Event Status Enable
*ESE?.............. Query
*ESR?.............. Event Status Register Query
*IDN? ............... Identification Query
*OPC ............... Operation Complete
*OPC? ............. Query
*RCL .. <0-10> . Recall
*RST ............... Reset. Resets the input and output buffers, resets the parser, and clears any pending commands
*SAV .. <0-10> . Save
*SRE ............... Service Request Enable
*SRE?.............. Query
*STB? .............. Status Byte Query
*TRG ............... Causes the DTS to initiate a measurement
*TST? .............. Test Instrument Query
3.3
ROOT COMMANDS
:RUN .......Causes the DTS to initiate measurement. Performs the same function as the *TRG.
:TER? .....The TER query will read the TRG Event Register to be read. When the register is read it is
cleared. A one informs the program that the trigger has occurred. Monitor this bit to know when
a take sample (burst), pulse find, cable measure or an internal/external calibration is complete.
:LER? .....The LER query will read the Local Event Register. When the query is received and the
register is read, it is cleared. A non-zero indicates that a reset is in progress.
:SDS? .....The SDS query reads the Special Device Register. When the query is received and the
register is read, it is cleared. This register is used to indicate when some commands are
complete when they don’t set a TRG or MAV bit. Same as bit 3 of a serial poll.
Section 3 | GPIB Interface | 51
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52 | Section 3 | GPIB Interface
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