Noise Figure Analyzers NFA Series User’s Guide Manufacturing Part Number: N8972-90115

Noise Figure Analyzers NFA Series User’s Guide Manufacturing Part Number: N8972-90115
Noise Figure Analyzers
NFA Series
User’s Guide
Manufacturing Part Number: N8972-90115
February 2013
Supersedes January 2011
© Copyright 2001-2013 Agilent Technologies
Safety Notices
This product and related documentation must be reviewed for familiarization with
safety markings and instructions before use.
This instrument has been designed and tested in accordance with IEC Publication
61010-1+A1+A2:1991 Safety Requirements for Electrical Equipment for
Measurement, Control and Laboratory Use and has been supplied in a safe
condition. The instruction documentation contains information and warnings which
must be followed by the user to ensure safe operation and to maintain the instrument
in a safe condition.
The information contained in this document is subject to change without notice.
Agilent Technologies makes no warranty of any kind with regard to this material,
including but not limited to, the implied warranties of merchantability and fitness
for a particular purpose. Agilent Technologies shall not be liable for errors contained
herein or for incidental or consequential damages in connection with the furnishing,
performance, or use of this material.
The following safety symbols are used throughout this manual. Familiarize yourself
with the symbols and their meaning before operating this instrument.
WARNING
Warning denotes a hazard. It calls attention to a procedure which, if not
correctly performed or adhered to, could result in injury or loss of life. Do not
proceed beyond a warning note until the indicated conditions are fully
understood and met.
CAUTION
Caution denotes a hazard. It calls attention to a procedure that, if not correctly
performed or adhered to, could result in damage to or destruction of the instrument.
Do not proceed beyond a caution sign until the indicated conditions are fully
understood and met.
NOTE
Note calls out special information for the user’s attention. It provides operational
information or additional instructions of which the user should be aware.
2
WARNING
This is a Safety Class 1 Product (provided with a protective earthing ground
incorporated in the power cord). The mains plug shall only be inserted in a
socket outlet provided with a protected earth contact. Any interruption of the
protective conductor inside or outside of the product is likely to make the
product dangerous. Intentional interruption is prohibited.
WARNING
If this product is not used as specified, the protection provided by the
equipment could be impaired. This product must be used in a normal condition
(in which all means for protection are intact) only.
WARNING
No operator serviceable parts inside. Refer servicing to qualified personnel. To
prevent electrical shock do not remove covers.
WARNING
For continued protection against fire hazard, replace line fuses only with the
same type and ratings (115V range; type F 5A 125V; 239V range F 5A 250V).
The use of other fuses or materials is prohibited.
CAUTION
To prevent electrical shock, disconnect the instrument from the mains (line) before
cleaning. Use a dry cloth or one slightly dampened with water to clean the external
case parts. Do not attempt to clean internally.
Environmental requirements: This product is designed for indoor use only and to
meet the following environmental conditions:
•
Operating temperature: 0° C to +55° C
3
•
Operating humidity: <95% relative
•
Altitude: up to 4500 m
Warranty
This Agilent Technologies instrument product is warranted against defects in
material and workmanship for a period of three years from date of shipment. During
the warranty period, Agilent Technologies Company will, at its option, either repair
or replace products which prove to be defective.
For warranty service or repair, this product must be returned to a service facility
designated by Agilent Technologies. Buyer shall prepay shipping charges to Agilent
Technologies and Agilent Technologies shall pay shipping charges to return the
product to Buyer. However, Buyer shall pay all shipping charges, duties, and taxes
for products returned to Agilent Technologies from another country.
Agilent Technologies warrants that its software and firmware designated by Agilent
Technologies for use with an instrument will execute its programming instructions
when properly installed on that instrument. Agilent Technologies does not warrant
that the operation of the instrument, or software, or firmware will be uninterrupted
or error-free.
LIMITATION OF WARRANTY
The foregoing warranty shall not apply to defects resulting from improper or
inadequate maintenance by Buyer, Buyer-supplied software or interfacing,
unauthorized modification or misuse, operation outside of the environmental
specifications for the product, or improper site preparation or maintenance.
NO OTHER WARRANTY IS EXPRESSED OR IMPLIED. AGILENT
TECHNOLOGIES SPECIFICALLY DISCLAIMS THE IMPLIED WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
4
EXCLUSIVE REMEDIES
THE REMEDIES PROVIDED HEREIN ARE BUYER’S SOLE AND
EXCLUSIVE REMEDIES. AGILENT TECHNOLOGIES SHALL NOT BE
LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR
CONSEQUENTIAL DAMAGES, WHETHER BASED ON CONTRACT, TORT,
OR ANY OTHER LEGAL THEORY.
Where to Find the Latest Information
Documentation is updated periodically. For the latest information about Agilent
NFA Noise Figure Analyzers, including firmware upgrades and application
information, please visit the following Internet URL:
http://www.agilent.com/find/nf/
5
6
Contents
1. Getting Started
What You will Find in this Chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
The Noise Figure Analyzer Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Product Family . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
3.0 GHz Mechanical Switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Microwave Front Panel Connector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Product Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Overview of the Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Overview of the Rear Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Overview of the Front Panel Keys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
How the Front Panel Keys are Organized . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Navigating Through the Menu System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Display Annotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Making a Fixed Frequency Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
Performing Common File Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
Formatting a Diskette . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
Saving a File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
Loading a File. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
Renaming a File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
Copying a File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
Deleting a File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
Working with Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
Using the Alpha Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46
2. Making Basic Measurements
What You will Find in this Chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50
7
Contents
Entering Excess Noise Ratio (ENR) Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Selecting a Common ENR Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Entering ENR Table Data for Normal Noise Sources . . . . . . . . . . . . . . . . . . . . . 52
Saving an ENR Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Entering a Spot ENR Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Entering a Spot Thot Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Using a Smart Noise Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Setting the Tcold value. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Setting the Measurement Frequencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Selecting Sweep Frequency Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Selecting List Frequency Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Selecting Fixed Frequency Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Setting the Bandwidth and Averaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Effect of Bandwidth and Averaging on Speed, Jitter, and Measurement Accuracy
71
Selecting a Bandwidth Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Setting Averaging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Calibrating the Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
To perform a calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Selecting the Input Attenuation Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Displaying the Measurement Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Selecting the Display Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Selecting Result Types to Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Graphical Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Setting the Scaling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Working with Markers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Indicating an Invalid Result. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
RF Input Over and Under Range Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . 103
IF Input Over and Under Range Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Example of a Basic Amplifier Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
8
Contents
Calibrating the Noise Figure Analyzer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105
Making Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .108
3. Advanced Features
What You will Find in this Chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
Setting up Limit Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Creating a Limit Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Using Loss Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Examples where Loss Compensation is applied . . . . . . . . . . . . . . . . . . . . . . . . 119
Configuring Fixed Loss Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Configuring Table Loss Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122
Working with S2P, S1, and S2 File Formats . . . . . . . . . . . . . . . . . . . . . . . . . . .127
Setting Temperature of Loss. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129
Making Manual Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .131
Manual Measurements Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133
4. Making Extended Frequency Measurements
What You will Find in this Chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .136
Overview of Configuring Extended Frequency Measurements. . . . . . . . . . . . . . .137
Measurement Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .139
Basic Measurement — No Frequency Conversion . . . . . . . . . . . . . . . . . . . . . .140
Frequency Down-converting DUT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .142
Frequency Up-converting DUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .145
System Downconverter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .148
Comparison of the 8970B and the NFA Series Measurement Modes . . . . . . . . . .151
Choosing and Setting Up the Local Oscillator. . . . . . . . . . . . . . . . . . . . . . . . . . . .152
Selecting a Local Oscillator for Extended Frequency measurements with the NFA
152
Selecting a Local Oscillator for the NFA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .153
9
Contents
Setting up the NFA to drive the Local Oscillator. . . . . . . . . . . . . . . . . . . . . . . . 154
Connecting the System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
Setting Up the Noise Figure Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
Measuring a Frequency-Converting DUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
Sidebands and Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
Signal Leakage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
LO Leakage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
LO Harmonics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
Other signals from the DUT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
Single Sideband Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
Double Sideband Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
Fixed IF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
Fixed LO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
Making Frequency-Converting DUT Measurements . . . . . . . . . . . . . . . . . . . . . . 172
Making Down-Converting DUT Measurements using a Fixed IF and Variable LO
(8970B Mode 1.3)172
Making Down-converting DUT Measurements using a Variable IF and Fixed LO
(8970B Mode 1.4)181
Making Up-converting DUT Measurements using a Fixed IF and Variable LO
(8970B Mode1.3 with SUM)182
Making Up-converting DUT Measurements using a Variable IF and Fixed LO
(8970B Mode1.4 with SUM)183
Measurements with a System Downconverter . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
USB, LSB or DSB? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
Measurement Modes with a DSB System Downconverter . . . . . . . . . . . . . . . . 186
Measurement Modes with an SSB System Downconverter . . . . . . . . . . . . . . . 187
FIXED IF, LSB: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
FIXED IF, USB:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
FIXED LO, LSB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
FIXED LO, USB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
10
Contents
Making System Downconverter Measurements . . . . . . . . . . . . . . . . . . . . . . . . . .194
Using a Fixed IF and Variable LO (8970B Mode1.1) . . . . . . . . . . . . . . . . . . . .195
Using a Variable IF and Fixed LO (8970B Mode1.2) . . . . . . . . . . . . . . . . . . . .204
Frequency Restrictions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .207
Glossary of Restricted Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .207
General Restrictions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .208
Frequency-Downconverting DUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .209
Frequency Up-converting DUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
System Downconverter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .213
5. Performing System Operations
What You will Find in this Chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .218
Setting the GPIB Addresses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .219
To Set the GPIB Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .219
Configuring the Serial Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .221
Configuring the Characteristics of an External LO . . . . . . . . . . . . . . . . . . . . . . . .223
Custom Command Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .223
Settling Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .226
Minimum and Maximum Frequencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .226
Multiplier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .227
Configuring the Internal Alignment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .228
Turning Alignment Off and On . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .228
Changing Alignment Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .228
Alignment of the YIG Tuned Filter (YTF). . . . . . . . . . . . . . . . . . . . . . . . . . . . .229
Displaying Error, System and Hardware Information . . . . . . . . . . . . . . . . . . . . . .230
Displaying the Error History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .230
Displaying System Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .230
Displaying Hardware Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .230
Presetting the Noise Figure Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .231
11
Contents
Defining the Power-On/Preset Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
Setting the Power On Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
Setting the Preset Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
Restoring System Defaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
Setting the Time and Date . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
To turn the time and date on and off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
To set the time and date . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
Configuring a Printer with the NFA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
To Configure a Printer with the NFA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
Testing Correct Printer Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
6. Front Panel Key Reference
MEASURE Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
Frequency/Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
Averaging/Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
Calibrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
Meas Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
Mode Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
ENR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
DISPLAY Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258
Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258
Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
Result . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
Marker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
CONTROL Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
Loss Comp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
Limit Lines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277
Full Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280
Corr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281
12
Contents
Sweep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .284
Restart. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .288
SYSTEM Keys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .289
System (Local) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .289
File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .302
Save Trace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .309
Preset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .309
Print Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .310
Print . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .312
Data Entry Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .313
Numeric Keys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .313
Back Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .313
Enter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .313
Up/Down Arrow Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .313
Display and Menu Control Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .314
Viewing Angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .314
On . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .314
Standby . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .314
Next Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .315
Zoom. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .315
Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .315
Tab Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .316
ÜPrev . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .316
Esc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .316
Preset/Power Up Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .317
Preset/Power Up — “Persistent” Group Items. . . . . . . . . . . . . . . . . . . . . . . . . .317
Preset/Power Up - “Survive Preset” Group Items . . . . . . . . . . . . . . . . . . . . . . .319
Unsaved Items . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .320
State Items . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .320
Default States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .321
13
Contents
7. Troubleshooting
What You’ll Find in This Chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 328
Before You Call Agilent Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329
Check the Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329
Read the Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330
Service Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330
Connector Care . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331
Contacting Agilent Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331
How to Return Your Analyzer for Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332
Detailing the Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332
Original Packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332
Other Packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334
NFA Battery Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335
Error Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336
Informational Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337
Error Queues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340
Error Message Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341
Error Message Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342
0: No Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343
-499 to -400: Query Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344
-199 to -100: Command Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346
-399 to -300 and 201 to 799: Device-Specific Errors . . . . . . . . . . . . . . . . . . . . 352
-299 to -200:
Execution Errors371
14
1
Getting Started
This chapter introduces you to basic features of the Noise Figure Analyzer,
including front panel and rear panel descriptions, and an overview of the
display annotation. You also learn how to make a basic fixed frequency
measurement.
15
Getting Started
What You will Find in this Chapter
What You will Find in this Chapter
This chapter introduces the basic functions of the Noise Figure
Analyzer (NFA). This chapter covers the following:
•
The Noise Figure Analyzer Features
•
Overview of the Front Panel
•
Overview of the Rear Panel
•
Display Annotation
•
Overview of the Front Panel Keys
•
Making a Fixed Frequency Measurement
•
Performing Common File Operations
•
Working with Tables
•
Using the Alpha Editor
16
Chapter 1
Getting Started
What You will Find in this Chapter
Figure 1-1
NFA with a Normal Noise Source connected
Chapter 1
17
Getting Started
The Noise Figure Analyzer Features
The Noise Figure Analyzer Features
Product Family
The Agilent Series Noise Figure Analyzer (NFA) family comprises the
following models:
•
The N8972A (NFA); frequency range 10 MHz to 1.5 GHz.
•
The N8973A (NFA); frequency range 10 MHz to 3.0 GHz.
•
The N8974A (NFA); frequency range 10 MHz to 6.7 GHz.
•
The N8975A (NFA); frequency range 10 MHz to 26.5 GHz.
3.0 GHz Mechanical Switch
The N8974A and N8975A NFA models have a mechanical switch fitted to
allow them to switch between the 10 MHz to 3.0 GHz frequency range and
the 3.0 GHz to 6.7 GHz and the 3.0 GHz to 26.5 GHz frequency ranges
respectively. If the frequency range you are working in crosses the 3.0 GHz
point, the mechanical switch operates. The mechanical switch has a limited
number of cycles over which it is reliable.
To maximize the switches reliable life, switching over the 3.0 GHz switch
should be limited where possible.
Microwave Front Panel Connector
The N8974A and N8975A NFA models are fitted with a precision 3.5mm
male input connector. The models are supplied with a Precision 3.5mm
Coaxial Adaptor (83059B). When making connection you need to ensure
you apply the correct torque and you use the adaptor where needed. Correct
torque value guidance is in the Agilent NFA Series Performance
Verification and Calibration Guide.
18
Chapter 1
Getting Started
The Noise Figure Analyzer Features
Product Options
The NFA family offers the following product options:
•
1D5 The Hi-Stability 10 MHz option.
Main Features
The NFA includes the following main features:
•
A dedicated user interface to allow easy measurement set up and
interpretation of results
•
A GPIB port to allow remote operation
•
Built-in 17cm color LCD display
•
Measurement results can be displayed in graphical, table or meter mode
•
Dual-trace display allows simultaneous display of any two of the
following noise parameters: Noise Figure, Gain, Y-Factor, Phot, Pcold,
Teffective
•
Measurement modes equivalent to the Agilent 8970B Noise Figure
Meter
•
Single-sideband and double-sideband measurements
•
Fully compatible with Agilent’s existing range of Noise Sources, for
example the 346 and 347 series
•
A dedicated 2nd GPIB allows control of a local oscillator
•
An internal disk drive and a 3.5" floppy disk drive for storing ENR
tables, instrument states, limits, frequency lists, loss compensation tables,
and screen captures
•
A Centronics printer port
•
An RS232 serial port for serial communication
•
Normal noise source ENR table entry from front panel, floppy disk, or
over the GPIB
•
Limit lines with pass/fail notification
Chapter 1
19
Getting Started
The Noise Figure Analyzer Features
•
Marker functions to display measurement data on a trace or a recalled
trace
•
Manual measurements which can be made on a single frequency point or
over a number of points over a frequency range
•
A Smart Noise Source (SNS) port, when connected to an SNS allows the
facility to automatically upload it’s ENR values and monitor the ambient
temperature of the SNS
20
Chapter 1
Getting Started
Overview of the Front Panel
Overview of the Front Panel
Figure 1-2
Table 1-1
Front Panel Overview
Front Panel Item Descriptions
Item
Description
1
Viewing Angle keys allow you to adjust the display so that it can be
optimally viewed from different angles.
2
The Esc (escape) key cancels any entry in progress. Esc clears error
messages from the display status line, clears data input entries, and
aborts a print (if one is in progress).
Chapter 1
21
Getting Started
Overview of the Front Panel
Table 1-1
Front Panel Item Descriptions
Item
Description
3
Menu keys are the unlabeled keys next to the screen. The menu key
labels are shown on the display next to these unlabeled keys.
See Chapter 6 , “Front Panel Key Reference” for a more extensive
description of all the keys.
4
The MEASURE functions allow you to configure the NFA parameters
needed for making measurements.
The Frequency/Points and Averaging/Bandwidth keys activate the
primary set up function menu keys.
The Calibrate key removes any second stage noise contribution from
the measurement. The ENR key accesses the ENR menu.
The Meas Mode and Mode Setup keys are used to configure the NFA
to measure mixers and devices at frequencies greater than the basic
frequency of the NFA using a Local Oscillator.
5
The DISPLAY functions allow you to configure the display results.
The Scale key allows you to set the scale of the graph results. The
Format key allows you to set the format of the result. The Marker key
allows you to control the markers and search the trace. The Result key
allows you set which measurements you want to display.
6
The CONTROL functions allow you to setup the NFA’s advanced
features. These are Loss Comp, Limit Lines, correction (Corr key)
setting including input calibration ranges, Sweep mode including
Manual Meas. Also, measurement Restart and a Full Screen display.
The Full Screen functions in all display formats.
7
SYSTEM functions affect the state of the NFA. Various setup and
alignment routines are accessed with the System key.
The green Preset key resets the NFA to a known state.
The File key menu allows you to save and load the various NFA file
types and access the File Manager. The Save Trace key executes the
Save function defined under File.
The Print Setup menu keys allow you to configure hardcopy output.
The Print key sends hardcopy data to the printer.
22
Chapter 1
Getting Started
Overview of the Front Panel
Table 1-1
Front Panel Item Descriptions
Item
Description
8
The Media Door on the right side of the front panel accesses the 3.5
inch disk drive.
9
The Data Entry Keys, which include the Up/Down arrow keys, RPG
(rotatable knob), and numeric keys, allow you to enter or change the
numeric value of an active function.
The Numeric Keys allows entry of exact values for many of the NFA
functions. To terminate a numeric, where no unit labels have been
presented, press the Enter key.
The RPG allows continuous change of functions such as marker
position.
The Up/Down arrow keys allow discrete increases or decreases of the
active function value.
10
EXT KEYBOARD. The EXT KEYBOARD connector is a 6-pin
mini-DIN connector for future use with PC keyboards. Not currently
supported.
11
PROBE POWER provides power for other accessories.
12
The ⇐ Prev key accesses the previously selected menu. Continuing to
press ⇐ Prev key takes you to earlier menus in the present menu
system.
13
NOISE SOURCE DRIVE OUTPUT +28V PULSED this connector
provides a 28 Vdc level to switch the noise source on. The noise source
is off when no voltage is applied.
14
Tab Keys are used to move between, table input fields, fields on forms,
and to move within the fields of the dialog box accessed by the File
menu keys.
15
INPUT 50Ω This is the input connector for the NFA.
N8972/3A models have a Type-N connector.
N8974/5A models have a precision 3.5 mm connector.
Chapter 1
23
Getting Started
Overview of the Front Panel
Table 1-1
Front Panel Item Descriptions
Item
Description
16
The
is active.
Next Window key selects which graph or result parameter
Pressing
Zoom key while in graph mode allows you to switch
between the dual-graph and single-graph display.
17
Press the Help key and then any front panel or menu key to get a short
description of the key function and the associated remote command.
The next key you press removes the help window from the display.
18
The Smart Noise Source (SNS) connector provides the interface to
upload the ENR data, monitor the ambient temperature, and switch the
SNS off and on.
19
The ?(On) key turns the NFA on, while the O (Standby) key switches the
NFA to standby.
After turning on the NFA, with the factory default Alignment running,
allow 60 minutes of warm-up time to ensure the NFA meets its
specifications.
24
Chapter 1
Getting Started
Overview of the Rear Panel
Overview of the Rear Panel
Figure 1-3
Table 1-2
Rear Panel Overview
Rear Panel Item Descriptions
Item
Description
1
Power input is the input for the AC line-power source. Make sure
that the line-power source outlet has a protective ground contact.
Chapter 1
25
Getting Started
Overview of the Rear Panel
Table 1-2
Rear Panel Item Descriptions
Item
Description
2
Line Fuse. The fuse is removed by twisting counterclockwise 1/4
turn. Replace only with a fuse of the same rating. See the label on the
rear panel and information in the Setup Guide.
3
Service Connector. The service connector is for service use only.
4
VGA OUTPUT drives an external VGA compatible monitor with a
signal that has 31.5 kHz horizontal, 60 Hz vertical synchronizing rate,
non-interlaced.
5
PARALLEL interface port is for printing only.
6
RS-232 interface supports remote instrument operation.
7
Presel Tune Connector it is not currently supported.
8
10 MHz REF IN accepts an external frequency source to provide the
10 MHz, −15 to +10 dBm frequency reference used by the NFA.
9
10 MHz REF OUT provides a 10 MHz, 0 dBm minimum, timebase
reference signal.
10
LO GPIB port is for the control of an external LO by the NFA.
11
MAIN GPIB interface port supports remote instrument operation.
12
AUX OUT (TTL) it is not currently supported.
13
AUX IN (TTL) it is not currently supported.
14
Power On Selection selects an instrument power preference. This
preference applies after power has been absent for > 20 seconds. The
PWR NORM position causes the instrument to remain off when power
is applied. The PWR ALWAYS ON position causes it to turn on. The
PWR ALWAYS ON mode is useful if an external power switch is used
to control a rack of several instruments.
26
Chapter 1
Getting Started
Overview of the Front Panel Keys
Overview of the Front Panel Keys
How the Front Panel Keys are Organized
The front panel keys are divided into four main groups:
•
MEASURE keys, which are used to configure the measurement
parameters, such as frequency range, bandwidth, number of
measurement points and so forth.
•
CONTROL keys, which are used to configure advanced measurement
parameters, such as Loss Compensation and Limit Lines
•
SYSTEM keys, which perform system-level operations such as
configuring the NFA’s GPIB address, displaying status information and
configuring an external LO.
•
DISPLAY keys, which adjust the display characteristics of the
measurement, for example setting which parameters are displayed,
whether the display format is graph, table or meter, adjusting the scaling
etc.
In addition to the four main groupings, the keys are also further grouped
according to key size and closeness to the display. The large keys placed in
column nearest the display (Frequency/Points, Averaging/Bandwidth,
Calibrate, Scale and Format) are typically the keys which you use most
frequently when performing a measurement.
Navigating Through the Menu System
Menu keys
Pressing any of the grey front panel keys in the MEASURE, DISPLAY,
RESULT or SYSTEM key groupings accesses menus of functions that are
displayed along the right-hand side of the display. These keys are called
menu keys. See Figure 1-4.
Chapter 1
27
Getting Started
Overview of the Front Panel Keys
Figure 1-4
Menu Keys
Action keys
Pressing any of the white keys (Calibrate, Full Screen, Restart, Save
Trace and Print) invokes an action and these keys are called action keys.
To activate a
menu key
function
To activate a menu key function, press the key immediately to the right of
the screen menu key. The menu keys that are displayed depend on which
front panel key is pressed and which menu level or page is selected.
When a menu key value is selected, it is called an active function. The
function label of the active function is highlighted after that key is selected.
For example, if you press the Frequency/Points key the menu of related
configuration parameters appears. If you now press the menu key labeled
Start Freq key, the Start Freq appears in the active function area. The Start
Frequency can be changed using any of the data entry controls.
Selecting a
Some menu keys have functions contained within them, for example, On
function within a and Off. To turn the function on, press the menu key so that On is
menu key
underlined. To turn the function off, press the menu key so that Off is
underlined.
28
Chapter 1
Getting Started
Overview of the Front Panel Keys
In some menus, one key label is always highlighted to show which key is
selected but the menu is immediately exited when a selection is made. For
example, when you press the Orientation key (a Print Setup menu key) its
own menu of keys appears. The Portrait key, which is the Orientation menu
default key, is highlighted. When you press another Orientation menu key,
the highlight moves to that key to show it is selected.
For a summary of all front panel keys and their related menu keys, see
Chapter 6 , “Front Panel Key Reference.”
Chapter 1
29
Getting Started
Display Annotation
Display Annotation
The display annotation, shown in Figure 1-5, is referenced by numbers.
Table 1-3 has a description and, where appropriate, a function key indicating
which key activates the function related to the annotation. Refer to Chapter
6 , “Front Panel Key Reference” for more information on a specific key.
Figure 1-5
Display Annotation
2
1
3
4
5
6
7
8
31
9
30
29
28
27
10
26
25
24
23
22
11
21
12
20
19
30
18
17
16
15
14
13
Chapter 1
Getting Started
Display Annotation
Each item is given a description and where applicable a function key
associated with it.
Table 1-3
Display annotation item descriptions
Item
Description
1
The active function area displays the label and value of the
currently active key.
2
The time and date display, controlled by the Time/Date menu
key, under the System key menus.
3
The marker numbers are displayed in this column, each row
displays the markers results. It is controlled by the Marker and
the State menu keys.
4
The markers frequency is displayed in this column. It is
controlled by the Marker and the State menu keys.
5
The upper trace measurement result is displayed in this column.
It is controlled by either the Result, Marker, State menu keys.
6
The lower trace measurement result is displayed in this column.
It is controlled by either the Result, Marker, State menu keys.
7
The GPIB annunciators RLTS.
The following GPIB modes are possible:
•
R — Remote operation
•
L — GPIB Listen
•
T — GPIB Talk
•
S — GPIB SRQ (Service Request)
8
The data invalid indicator appears when a measurement starts. It
disappears after a complete sweep.
9
The key menu title, this is dependent on which key is selected.
10
The key menu, see key label descriptions in Chapter 6 , “Front
Panel Key Reference”.
Chapter 1
31
Getting Started
Display Annotation
Table 1-3
Item
11
Display annotation item descriptions
Description
The frequency span or stop frequency, controlled by the
Freq Span or Stop Freq key.
12
Displays the measurement correction state, uncorrected or
corrected. Controlled by the calibration state and the Corr key.
13
Displays the Loss Compensation status, On or Off. Controlled
by the Loss Comp key.
14
The number of points, controlled by the Points menu key.
15
Displays the value of attenuation being applied. The left item is
the RF attenuator and the right item is the microwave attenuator.
On the N8972/3A only the RF attenuator status is displayed.
16
The bandwidth, controlled by the Bandwidth menu key.
This is fixed at 4 MHz on the N8972A model.
17
The number of averages, controlled by the Averages menu key.
18
The center frequency or start frequency, controlled by the
Center Freq or Start Freq menu keys.
19
The Tcold temperature value, controlled by the Tcold menu key.
20
The display status line, displays instrument status and error
messages.
21
The lower trace lower limit, controlled by the Lower Limit menu
key.
22
The lower trace unit of measurement on the Y-axis, controlled
by the Result key or Scale menu key.
23
The lower trace scale, controlled by the Scale/Div menu key.
24
The lower trace result type, controlled by the Result key.
25
The lower trace upper limit, controlled by the Upper Limit menu
key.
26
The upper trace lower limit, controlled by the Lower Limit menu
key.
32
Chapter 1
Getting Started
Display Annotation
Table 1-3
Figure 1-6
Display annotation item descriptions
Item
Description
27
The upper trace unit of measurement on the Y-axis, controlled
by the Result key or Scale menu key.
28
The upper trace scale, controlled by the Scale/Div menu key.
29
The upper trace result type, controlled by the Result key.
30
The upper trace upper limit, controlled by the Upper Limit menu
key.
31
The limit line failure indicator.
Shown in
Figure 1-6
The measurement mode status, controlled by the Meas Mode
key. This information is displayed by default. The status
disappears when the marker results are switched on.
Measurement Mode Status
Basic Setup Measurement Mode
Using a Converter Measurement Mode
Chapter 1
33
Getting Started
Making a Fixed Frequency Measurement
Making a Fixed Frequency Measurement
The Fixed Frequency Measurement is the simplest type of measurement to
explain, in terms of getting you started making measurements.
NOTE
You can experiment with the keys without damaging the NFA. To return to a
known state at anytime, press the green Preset key.
Noise figure measurements are made by measuring the output power of the
DUT for two different input noise power levels. Typically, the high power
input comes from a calibrated noise source, and the low power input uses the
noise power generated at ambient temperature.
A fixed frequency measurement is made by measuring a device at a specific
frequency. To display the result on the NFA use the meter display format, as
this is ideal for displaying fixed results. To make a fixed frequency
measurement on a device using the method described, its operating
frequency range must be within the frequency range of the NFA and requires
no frequency conversion.
The techniques used in the procedure are explained in greater detail in
Chapter 2 , “Making Basic Measurements”.
You need an appropriate noise source, either an SNS or a normal noise
source. The normal noise source input is connected to the 28V OUTPUT
using a BNC cable and its output is connected to the INPUT 50 W. The SNS
input is connected to the SNS port using the 11730A cable and its output is
connected to the INPUT 50 W.
34
Chapter 1
Getting Started
Making a Fixed Frequency Measurement
The following example measures the corrected noise figure and gain of a
device at a frequency of 900 MHz and verifies it meets the manufacture’s
specification listed in Table 1-4. The averaging is On and set to 10. The
bandwidth is set to the default 4 MHz.
Table 1-4
The Example DUT Specifications
Frequency Range
Typical Gain
Minimum Gain
Typical Noise
Figure
900 MHz
23 dB
17 dB
3.5 dB
When you are making measurements, follow the procedure and change the
values to meet your needs.
Step 1. Turn the instrument on by pressing On and wait for the power-up process to
complete.
NOTE
To obtain greater accuracy, it is recommended the NFA warm up for at least
one hour with Alignment(On). The default setting is Alignment(On)
Step 2. Press System, More 1 of 3, Power On/Preset, Preset (Factory).
Press the green Preset key.
NOTE
If the noise source ENR measurement table has been entered previously, you
can use this data to calibrate the NFA. The NFA interpolates points
automatically. Hence, you ignore Steps 3 and 4. See “Entering Excess Noise
Ratio (ENR) Data” on page 51.
The normal noise source ENR values are typically found on the body of the
noise source, the certificate of calibration, or on the diskette supplied with
the noise source. The SNS ENR values are uploaded to the NFA.
Step 3. Press the ENR key, and set the ENR Mode menu key to ENR Mode(Spot).
Chapter 1
35
Getting Started
Making a Fixed Frequency Measurement
Step 4. Press the Spot ENR menu key and enter an ENR value if different from the
default value.
If the frequency you want to measure is not a listed ENR value, then you
need to interpolate to an appropriate value. The default value is 15.200 dB.
Step 5. Select the frequency you want to measure using the Frequency/Points key.
Press the Frequency/Points key. Press the Freq Mode menu key and select
the Fixed menu key. The Freq Mode menu key has Fixed mode displayed.
Press the Fixed Freq menu key and enter the numeric frequency value you
want to measure using the numeric key pad. On this occasion enter 900.
Terminate the value using the unit label keys. On this occasion MHz.
Step 6. Select the averaging and bandwidth you want using the
Averaging/Bandwidth key.
Press the Averaging/Bandwidth key and set the averaging to On, by
selecting the Averaging(On) menu key.
Press the Averages menu key and enter the value you want, on this occasion
enter 10. Terminate it with the Enter key. The default value is 1.
NOTE
On the N8972A model, the average mode menu key is unavailable. The
average mode is performed at the default Average Mode(Point). On other
models set the averaging mode to Average Mode(Point). See “Selecting the
Averaging Mode” on page 72 for an explanation of these averaging modes.
Essentially in Fixed Frequency mode either averaging mode gives an
identical result.
Press the Bandwidth menu key and select the bandwidth value you want
from the list presented to you. On this occasion, the default 4 MHz value is
used. The N8972A only offers a 4 MHz bandwidth.
36
Chapter 1
Getting Started
Making a Fixed Frequency Measurement
Step 7. Connect the normal noise source input to the NFA’s 28V OUTPUT with a
BNC cable or if using an SNS connect it to the SNS port. Connect the
preferred noise source’s output to the INPUT 50 W.
NOTE
When using the N8974A and N8975A care must be taken to torque the
precision 3.5mm connector to the correct value. To find the correct value of
torque to apply, see the Performance Verification and Calibration Guide.
Step 8. Set the display mode to meter mode.
Press the Format key, the Format menu key and select the Meter menu key.
Step 9. Press the Calibrate key twice.
The first time you press the key you will be prompted to press it again. This
two-stroke calibration is a safety feature, it keeps you from accidentally
pressing the Calibrate key and erasing any previous calibration data.
The calibration corrects for any second stage noise contribution caused by
the NFA. When the calibration is complete the Uncorr text in the bottom
right hand corner changes to Corr text.
The calibration is performed at the default input attenuator settings. If you
need to change these settings, see “Selecting the RF Input Attenuation
Range” on page 78.
Step 10. Connect the device under test between the noise source output and the NFA’s
input.
The measurement result is displayed in meter format, similar to Figure 1-7.
Chapter 1
37
Getting Started
Making a Fixed Frequency Measurement
Figure 1-7
Typical Fixed Frequency Measurement Result in Meter Format.
The result displayed in Figure 1-7 shows the DUT noise figure and gain at
900 MHz.
Thus the DUT meets the manufacturer’s specification as listed in Table 1-4.
38
Chapter 1
Getting Started
Performing Common File Operations
Performing Common File Operations
This section describes how to use the functions located under the front-panel
File key. This section covers:
•
•
•
•
•
•
Formatting a diskette
Saving a file
Loading a file
Renaming a file
Copying a file
Deleting a file
Formatting a Diskette
You can format a diskette in the NFA. The format is MS-DOS. It is not
necessary to format your diskette with the NFA; pre-formatted disks can be
used with the NFA.
Step 1. Place the diskette you wish to format into the diskette drive (A:) of the NFA.
Step 2. Access the file manager menu by pressing File key, File Manager. See
Figure 1-8.
Chapter 1
39
Getting Started
Performing Common File Operations
Figure 1-8
File Manager Menu
Step 3. Start the format process by pressing Format, then Enter.
CAUTION
To abort disk format press any key, except Enter.
When a disk is formatted all data on the disk is destroyed. A dialog box
appears on the NFA display to warn you, allowing you the opportunity to
abort formatting.
Step 4. Press Enter, a second time to format the disk.
The format process takes approximately three minutes.
You are now ready to save files to the disk.
40
Chapter 1
Getting Started
Performing Common File Operations
Saving a File
You can save files (ENR tables, states, traces, limits, frequency lists, loss
tables, or screens) to a floppy disk (A:), or the internal drive (C:) of the
NFA.
Step 1. To access the Save menu press File, Save.
Step 2. Select the type of file you want to save.
For example, if you have limit line table data present and want to save it,
press Limits.
Step 3. Select the limit line table file you wish to save (1, 2, 3 or 4).
For example, to save file 2, press 2.
Step 4. Enter a filename using the Alpha Editor menu keys. See “Using the Alpha
Editor” on page 46.
NOTE
You must select a unique filename and no greater than eight characters. The
NFA does not allow you to overwrite an existing file. If you select a file
name that already exists, the NFA displays the error message: File
already exists.
Step 5. Select the drive you wish to save to by pressing Tab →, to move to directory
and file list, press Select.
NOTE
If the correct drive is not listed in the Path: field, highlight “..” at the top
of the directory list. This enables you to move up a directory. Press Select.
To highlight the desired drive,[-A-] or [-C-]) use the arrow keys or the
RPG, press Select when highlighted.
Step 6. Press Enter, to save the file to the drive.
Chapter 1
41
Getting Started
Performing Common File Operations
Loading a File
You can load files (ENR tables, states, limits, frequency lists, or loss tables)
from a floppy disk (A:\), or the internal drive (C:\).
NOTE
Files saved in previous versions of firmware can not be loaded into a NFA
with newer firmware.
NOTE
Not all the file types you save can be loaded back into the NFA. For
example, screen files and trace files. The trace file is in a CSV (comma
separated value) format, designed for use with a PC.
Step 1. To access the Load menu press File, Load.
Step 2. Select the type of file you want to load (ENR tables, states, limits, frequency
lists, or loss tables).
Step 3. Select the drive where your file is located by pressing Tab →. Use the RPG
to highlight [-C-] or [-A-], then press Select.
Step 4. Select the file you want to load into the NFA by changing the highlighted file
with the up or down arrow keys to highlight the file name.
Step 5. Press Enter to load the specified file.
Renaming a File
You can rename a file in the [-C-] or [-A-] drive as follows:
Step 1. Press File, File Manager, Rename to access the Rename menu items.
Step 2. Select the type of file you want to rename (ENR tables, states, traces, limits,
frequency lists, loss tables, or screens).
For example, if you are renaming a ENR table file, press ENR.
Step 3. Select the drive where your file is located, by pressing the Tab → key, press
Select. To change drive, use the arrow keys to highlight [-C-] or [-A-],
then press Select.
42
Chapter 1
Getting Started
Performing Common File Operations
Step 4. Select the file you want to rename by moving the cursor with the RPG or
arrow keys to highlight the file name.
Step 5. Press Tab → to enter the Alpha Editor menu. File names are limited to eight
(8) characters.
Step 6. Press Enter and your file is now renamed and visible within the directory
displayed on your NFA.
Copying a File
This allows you to copy a file to a different location on both the [-C-] and
[-A-] drive.
Step 1. To access the Copy menu press File, File Manager, Copy.
Step 2. Put a formatted floppy in the A: drive.
Step 3. Select the type of file you want to copy (ENR tables, states, traces, limits,
frequency lists, loss tables or screens).
For example, if you are copying a State file, press State.
Step 4. Select the drive where your file is located, by pressing Tab → to highlight
the From:Path: field. Select the drive, using the RPG or arrow keys to
highlight [-C-] or [-A-], then press Select.
Step 5. Select the file you wish to copy by highlighting the filename using the
front-panel knob or arrow keys.
Step 6. Press Tab → to move to the To:Path: field and select the drive where you
want to copy the file using the RPG or arrow keys then press Select.
NOTE
If the correct drive is not listed in the Path: field, highlight “..” at the top
of the directory list. This enables you to move up a directory. Press Select,
to highlight the desired drive, ([-A-] or [-C-]) then press Select again.
Step 7. Copy the file by pressing Enter.
Chapter 1
43
Getting Started
Performing Common File Operations
Deleting a File
This allows you to delete a file from the [-C-] or [-A-] drive.
Step 1. To access the Delete menu press File, File Manager, Delete.
Step 2. Select the type of file you want to delete (ENR tables, states, traces, limits,
frequency lists, loss tables, or screens).
Step 3. Select the drive where the file you wish to delete is located, by pressing Tab
→ then using the RPG or arrow keys to highlight [-C-] or [-A-], then
press Select.
NOTE
If the correct drive is not listed in the Path: field, highlight “..” at the top
of the directory list. This enables you to move up a directory. Press Select,
to highlight the desired drive, ([-A-] or [-C-]) then press Select again.
Step 4. Select the file you want to delete by moving the cursor with the RPG or
arrow keys to highlight the file name.
Step 5. Press Enter and your file is now deleted and is no longer visible in the
directory displayed on your NFA.
44
Chapter 1
Getting Started
Working with Tables
Working with Tables
The Frequency List, ENR Table, Limit Line Editor, and Loss Compensation
Tables use table forms. The following is an overview of how to use the
features in these tables.
Table 1-5
Using Tables
To...
Use the...
Move the highlight bar within the table
Tab keys
Bring the highlight bar to the top of the
table
Home key
Clear the table of all entries
Clear Table menu key
Delete a single row entry
Delete Row menu key
Add a new entry
Add menu key
Move the highlight bar up one row
Row Up menu key
Move the highlight bar down one row
Row Down menu key
Move the table up a page block
Page Up menu key
Move the table down a page block
Page Down menu key
Enter a value
Numerical key pad
Terminate a value
The unit values presented by the
menu keysa
Connect Limit Line points
The arrow keys or the RPG
a. A limit line value is a unitless value and it depends on the
result’s scale unit used.
Chapter 1
45
Getting Started
Using the Alpha Editor
Using the Alpha Editor
The Alpha Editor is a menu driven text entry system. You enter the character
data with the menu keys. If numeric data is needed also use the numeric
keypad. To edit the data use the Back Space key. After completing the entry
terminate it by pressing the Enter key.
The Alpha Editor allows you to:
•
name files when saving.
•
enter the alphabetical portion of the model ID and the serial number of
the noise source in an ENR table.
•
create suffix and prefix commands used to set the External LO frequency
and power levels.
The LO Commands Alpha Editor have more character options available, see
Figure 1-9.
46
Chapter 1
Getting Started
Using the Alpha Editor
Figure 1-9
Alpha Editor Character Set
The Alpha Editor is used as follows. In the example, a three character file
name, NEW, is created.
Step 1. Press the HIJKLMN key.
Step 2. Press the N key.
Step 3. Press the ABCDEFG key.
Step 4. Press the E key.
Step 5. Press the VWXYZ key.
Step 6. Press the W key.
Chapter 1
47
Getting Started
Using the Alpha Editor
48
Chapter 1
2
Making Basic Measurements
This chapter describes how to make basic noise figure measurements using
your NFA and also covers the most common measurement related tasks.
49
Making Basic Measurements
What You will Find in this Chapter
What You will Find in this Chapter
This chapter describes the procedures to set up the NFA and uses a basic
example to demonstrate the NFA measuring noise figure and gain of a
device which has no frequency conversion.
•
Entering Excess Noise Ratio (ENR) Data
•
Setting the Measurement Frequencies
•
Setting the Bandwidth and Averaging
•
Calibrating the Analyzer
•
Displaying the Measurement Results
•
Example of a Basic Amplifier Measurement
50
Chapter 2
Making Basic Measurements
Entering Excess Noise Ratio (ENR) Data
Entering Excess Noise Ratio (ENR) Data
You can enter ENR data for the noise source you are using as a table of
values or as a single spot value. The table of values are used for
measurements at several frequencies. The single spot value is used for single
frequency measurements or it is applied across the whole frequency
measurement range.
There are two types of noise source. The first type, for example,
Agilent 346B, a normal noise source. These need their ENR data to be
entered manually either using the ENR data stored previously on a diskette
or by using the keypad. The other type, for example, Agilent N4000A, a
Smart Noise Source (SNS), can upload the data automatically or when
requested.
Selecting a Common ENR Table
You can use the same, Common, ENR table for calibration and making
measurements, or you can use separate, Meas and Cal, ENR tables when a
different noise source is used during DUT measurements from that used for
calibration.
NOTE
ENR tables can contain up to 81 frequency points.
To use the same ENR table for calibration and measurement, press the
Common Table menu key to select Common Table(On); see Figure 2-1.
This is the default setting. In this mode the Cal Table is not accessible.
Chapter 2
51
Making Basic Measurements
Entering Excess Noise Ratio (ENR) Data
Figure 2-1
Menu Keys showing Common ENR Table On
To use different ENR tables for calibration and measurement, press the
Common Table menu key to select Common Table(Off); see Figure 2-2.
In this mode, the Cal Table menu key is accessible. This is the ENR table of
the noise source used to calibrate the NFA. The Meas Table is used to make
measurements. In Common Table(Off) mode the ENR Table is the
Meas Table in the Common Table(On) mode.
Figure 2-2
Menu Keys showing Common ENR Table Off
NOTE
If you are using an SNS when Common Table(Off) is set, you need to set
Auto Load ENR(Off) and use the Fill Table From SNS menu key. See
“Loading the SNS ENR data to the Measurement or Calibration Table.” on
page 61.
Entering ENR Table Data for Normal Noise Sources
You can enter ENR data in the form of an ENR table in four ways:
•
52
manually by inputting the required frequencies and corresponding ENR
values
Chapter 2
Making Basic Measurements
Entering Excess Noise Ratio (ENR) Data
NOTE
•
loading the ENR data from a diskette, on which the data has been
previously stored
•
loading the ENR data from the internal memory, where the data has been
previously stored
•
loading the ENR data over GPIB, see the Programmer’s Reference for
more details
Agilent normal noise sources have the ENR values printed on the body of
the device. These ENR values are also provided within separate text in the
form of a calibration report, and on a diskette which is supplied with every
Agilent noise source.
To enter ENR table data manually
NOTE
If the NFA has arrived from the factory, and you are entering ENR data for
the first time, the ENR table is empty. You can create this condition with an
NFA which has been used previously by pressing Clear Table. The typical
display is shown in Figure 2-3.
Enter the ENR data manually as follows:
Step 1. Press the ENR key, and the ENR Table menu key.
An ENR Table appears on the display with the first frequency point in the
table highlighted, see Figure 2-3. For details on working with tables, see
“Working with Tables” on page 45.
Chapter 2
53
Making Basic Measurements
Entering Excess Noise Ratio (ENR) Data
Figure 2-3
An Empty ENR Table
Step 2. Optional Step
Press the Serial Number menu key and enter the noise source serial number
using the numeric keys and the Alpha Editor.
For details on using the Alpha Editor, see “Using the Alpha Editor” on page
46.
Step 3. Optional Step
Press the ID menu key and enter the noise source model number using the
numeric keys and the Alpha Editor.
Step 4. Press the Edit Table menu key to enter the noise source ENR values.
The table editing and navigation menu items now appear.
Step 5. Enter the frequency value in the table using the numeric keys. Terminate it
using the unit menu keys.
Step 6. Press the Tab —> key to move the highlight to the ENR Value column and
enter the corresponding ENR value of the ENR list.
54
Chapter 2
Making Basic Measurements
Entering Excess Noise Ratio (ENR) Data
When terminating the ENR value you can use either dB, K, C, or F menu
keys. The K, C, or F entry is converted to appear in the table as dB.
Step 7. Press the Tab —> key to move the highlight to the Frequency column and
enter the next frequency value on the ENR list.
Step 8. Repeat steps 5 to 7 until all the frequency and ENR values you need are
entered.
Step 9. After completing the ENR table entries, press the Prev key or ENR key to
return to the ENR menu.
Step 10. Optional Step
Once you have completed entering the ENR data, save the ENR table using
the File key.
For details on saving files, see “Saving an ENR Table” on page 58.
NOTE
ENR table data survives a power cycle and preset (except
Restore Sys Defaults). You only need to save the ENR data to save you
from entering the data again.
Chapter 2
55
Making Basic Measurements
Entering Excess Noise Ratio (ENR) Data
Figure 2-4
A Typical ENR Table after data entry
NOTE
You can insert the frequencies into the ENR Table entry in any order, as the
NFA automatically sorts the frequency list into ascending order.
NOTE
When results are needed at non-cardinal ENR data points, a linearly
interpolated value is automatically used at these points.
To load ENR data from memory
If the noise source you are using has its ENR data supplied or previously
stored on a diskette or internal memory, you can load this ENR data into the
NFA as follows.
Step 1. If the ENR file is on diskette, insert the diskette into the floppy drive of the
NFA.
For more details on loading files, see “Loading a File” on page 42.
Step 2. Press the File key.
56
Chapter 2
Making Basic Measurements
Entering Excess Noise Ratio (ENR) Data
Step 3. Press the Load menu key to access the file system.
Step 4. Press the ENR menu key.
Step 5. Press either the Meas Table or Cal Table menu key.
A list of available files on the [-A-] or [-C-] drive is displayed. Use the
arrow keys to access the appropriate file.
Step 6. Press the Enter key.
A Loading File Warning: this may take some time prompt
appears on the display and disappears when complete. On completion a
message, for example, C: xxx.ENR file loaded appears in display
status line.
Chapter 2
57
Making Basic Measurements
Entering Excess Noise Ratio (ENR) Data
Saving an ENR Table
You can save an ENR table to the NFA’s internal memory or to floppy disk
as follows:
Step 1. Press the File key.
Step 2. Press the Save menu key.
Step 3. Press the ENR menu key.
Step 4. Press either the Meas Table or Cal Table menu key. Also, if you are using an
SNS, an SNS menu key is available to select.
The Alpha Editor now appears, allowing you to create a name for the file.
Step 5. Input the name of the ENR table.
See “Using the Alpha Editor” on page 46 for details on using editor.
Step 6. Select using the arrow keys whether you want to save the files to the [-A-]
or [-C-] drive.
Step 7. Press Enter to save the file.
Entering a Spot ENR Value
When making a measurement in fixed frequency mode you can enter a
specific spot ENR value corresponding to the fixed frequency. The spot
ENR value can also be applied across the whole measurement frequency
range.
To enter a Spot ENR value:
Step 1. Press the ENR key, then the Spot menu key.
Step 2. Press the Spot ENR menu key.
Step 3. Enter an ENR value using the numeric keys and terminate it using the unit
termination menu keys. The default value is 15.20 dB.
NOTE
If you are using a noise source with a calibrated ENR list and the frequency
you want to measure is not a listed ENR value, then you need to interpolate
the ENR list to an appropriate value.
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Chapter 2
Making Basic Measurements
Entering Excess Noise Ratio (ENR) Data
To Enable Spot ENR Mode
Step 1. Press the ENR key, and select the ENR Mode(Spot) menu key.
Step 2. Press the Spot menu key, and select the Spot Mode(ENR) menu key.
Entering a Spot Thot Value
When making a manual measurement you can enter a specific spot Thot
value. The spot Thot value is applied across the whole measurement
frequency range
To enter a Spot Thot value:
Step 1. Press the ENR key, then the Spot menu key.
Step 2. Press the Spot Thot menu key.
Step 3. Enter a Thot value using the numeric keys and terminate it using the unit
termination menu keys. The default value is 9892.80 K.
To Enable Spot Thot Mode
Step 1. Press the ENR key, and select the ENR Mode(Spot) menu key.
Step 2. Press the Spot menu key, and select the Spot Mode(Thot) menu key.
Chapter 2
59
Making Basic Measurements
Entering Excess Noise Ratio (ENR) Data
Using a Smart Noise Source
NOTE
If there is an SNS connected to the NFA’s Smart Noise Source port, the NFA,
by default, selects the SNS as its noise source. If an SNS is not connected the
NFA uses the normal noise source.
Selecting the Source Preference
If noise sources are connected to both ports you need to select a preference
either Preference(Normal) or Preference(SNS). The default setting is
Preference(SNS).
To select a noise source preference:
Step 1. Press the ENR key.
Step 2. Press the SNS Setup menu key.
Step 3. Press the Preference menu key changing it from the default
Preference(SNS) to Preference(Normal).
Loading the SNS ENR data to the Common Table.
You can enable the NFA to automatically upload the ENR data to the
Common Table. To enable automatic loading on power up or the connection
of the SNS to the NFA’s Smart Noise Source port, set Auto Load ENR(On).
This enables the ENR data to load into the Common Table automatically. If
you do not want to automatically upload the ENR data into the Common
Table, press Auto Load ENR(Off).
If you have selected Auto Load ENR(Off), you can use the
Fill Table From SNS menu key to upload the ENR data from the SNS. The
Fill Table From SNS menu key is found under the ENR Table menu key. It
is only active when an SNS is connected. This allows you to choose when to
upload the ENR data to the ENR Table.
CAUTION
Do not disconnect the noise source from the NFA port while the data is being
transferred.
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Chapter 2
Making Basic Measurements
Entering Excess Noise Ratio (ENR) Data
Loading the SNS ENR data to the Measurement or Calibration Table.
NOTE
When an SNS is connected and Auto Load ENR(On) enabled, the
Common Table(On) is set automatically. Hence, the SNS ENR data is
loaded into the common ENR table.
You can use the Fill Table From SNS menu key to upload the ENR data
from the SNS. This allows you to choose between Meas Table or Cal Table,
as the destination for the ENR data.
Step 1. Press the ENR key.
Step 2. Press the SNS Setup menu key.
Step 3. Press the Auto Load ENR menu key setting it to Auto Load ENR(Off).
Step 4. Press the Common Table menu key setting it to Common Table(Off).
Step 5. Press the Meas Table or Cal Table menu key.
Step 6. Press the Fill Table From SNS menu key and wait until all the data is
uploaded.
CAUTION
Do not disconnect the noise source from the NFA port while the data is being
transferred.
Chapter 2
61
Making Basic Measurements
Entering Excess Noise Ratio (ENR) Data
Setting the Tcold value
When making measurements in different ambient temperature conditions
you can change the Tcold value.
The default temperature value is set at 296.50K. The Tcold menu key is set to
Tcold(Default) to confirm this default temperature.
There are three methods of changing the Tcold value. These are dependant on
the type of noise source you are using.
•
The first method is applicable when using either type of noise source and
allows you to enter a Tcold value manually. This method is explained in
“Changing the User Tcold value manually” on page 62.
•
The second method is applicable when using the SNS noise source and it
uploads the value automatically and updates the value after every sweep.
This method is explained in “Setting the SNS Tcold value to Update
Automatically” on page 63.
•
The third method is applicable when using the SNS where you can set the
value to be updated as you need. This method is explained in “Setting the
SNS User Tcold value” on page 64.
Changing the User Tcold value manually
To change the User Tcold value:
Step 1. Press the ENR key.
Step 2. Press the Tcold menu key.
NOTE
When using an SNS, the SNS Tcold menu key must set to SNS Tcold(Off)
for this feature to work.
Step 3. Press the User Tcold menu key setting it from the default User Tcold(Off)
to User Tcold(On).
The Tcold menu key, under the ENR menu keys, is now set to Tcold(User)
to confirm you are using this temperature mode.
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Entering Excess Noise Ratio (ENR) Data
Step 4. Press the User Value menu key.
Enter a Tcold value using the numeric keys and terminate it using the unit
termination menu keys.
The unit termination menu keys are in K (Kelvin), C (Celsius) or
F (Fahrenheit).
NOTE
The lower limit is 0K and upper limit is 29,650,000K. The default value is
296.5K. The K value is always displayed. The K values are converted from
the entered oC and oF.
Setting the SNS Tcold value to Update Automatically
This feature is only available when an SNS is connected to the NFA.
To set the SNS Tcold value:
Step 1. Press the ENR key.
Step 2. Press the Tcold menu key.
Step 3. Press the SNS Tcold menu key, if required, setting it to SNS Tcold(On).
The Tcold menu key, under the ENR menu keys, is now set to Tcold(Auto)
to confirm you are using this temperature mode.
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Entering Excess Noise Ratio (ENR) Data
Setting the SNS User Tcold value
This feature only works when an SNS is connected to the NFA.
To change the User Tcold value:
Step 1. Press the ENR key.
Step 2. Press the Tcold menu key.
NOTE
When using an SNS, SNS Tcold must set to SNS Tcold(Off) for this feature
to work.
Step 3. Press the User Tcold menu key changing it from the default
User Tcold(Off) to User Tcold(On).
Step 4. Press the User Tcold From SNS menu key.
The NFA uploads the Tcold value from the SNS and displays the value in the
User Value menu key.
The Tcold menu key, under the ENR menu keys, is now set to Tcold(User)
to confirm you are using this temperature mode.
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Setting the Measurement Frequencies
Setting the Measurement Frequencies
Before you set the frequencies you want to measure, you need to select a
frequency mode. Three frequency modes are available:
•
Sweep — the measurement frequencies are obtained from the start and
stop (or equivalent center and span) frequencies and the number of
measurement points.
•
List — the measurement frequencies are obtained from the frequency list
entries.
•
Fixed — where the measurement frequency is taken at a single fixed
frequency. An example of using this mode is explained in “Making a
Fixed Frequency Measurement” on page 34.
Selecting Sweep Frequency Mode
In sweep frequency mode you set the start and stop frequencies (or
equivalent center and span frequencies) over which the sweep is made. You
also need to set the number of measurement points. These measurement
points are equally spaced over the frequency span. The maximum number of
points is 401and the default number of points is 11.
CAUTION
The N8974A and N8975A NFA models have a mechanical switch fitted to
allow them to switch between the RF frequency range and the microwave
frequency range. If the frequency range you are working in crosses the
3.0 GHz point, the mechanical switch operates. The mechanical switch has a
limited number of cycles over which it is reliable.
Switching over the 3.0 GHz switch should be limited where possible.
NOTE
You can press Full Span at anytime to return the frequency range to the
specific NFA model’s full range setting. If you do this after a calibration and
the calibration has been made over a narrower frequency range, the
calibration is invalid.
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Setting the Measurement Frequencies
To make a measurement over a specific frequency range:
Step 1. Press the Frequency/Points key.
Step 2. Press the Freq Mode menu key to select frequency mode to
Freq Mode(Sweep).
Step 3. Set the frequency range by either entering the Start Freq and Stop Freq
frequencies, or the Center Freq and the Freq Span.
Use the numeric key pad to enter the value you want. Use the unit menu keys
to terminate the number.
Step 4. Press the More 1 of 2, Points menu keys.
Step 5. Enter the number of measurement points using the numeric keys. Press the
Enter key to terminate.
NOTE
The greater number of frequency points selected, the greater the time
required by the measurement.
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Setting the Measurement Frequencies
Selecting List Frequency Mode
List frequency mode allows you to enter the frequency points where
measurements are made. This allows you to specify measurement points, for
example, in areas of interest that would have less coverage than in the sweep
mode to allow unevenly spaced measurement points.
Frequency lists are limited to 401 entries.
To set the NFA to use the data in the frequency list table:
Step 1. Press the Frequency/Points, Freq Mode menu keys.
Step 2. Press the Fixed menu key to set the frequency mode to Freq Mode(List).
You can create a frequency list in the following ways:
•
Manually, by specifying each individual point.
•
From the swept points, by specifying the measurement frequency range
and setting the NFA to generate equally spaced points within that range,
using the Fill menu key.
•
Loading a list from the internal memory or diskette, where the data has
been previously stored.
•
Loading a list over GPIB; see the Programmer’s Reference if you want
to use this method.
To Create a Frequency List Manually
Step 1. Press the Frequency/Points key and press the More 1 of 2 menu key.
Step 2. Press the Freq List menu key.
A Frequency List table appears on the display.
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Setting the Measurement Frequencies
Figure 2-5
An Empty Frequency List
NOTE
You do not need to enter the frequency values in ascending order, as the NFA
continually sorts the values into ascending order.
Step 3. Press the More 1 of 2, Clear Table menu keys.
You are prompted to press this key again, this feature ensures you do not
accidently clear a valid Frequency list table. Press the Clear Table menu key
again. Clearing the table allows you to start entering points knowing there
are no previous entries remaining.
The first frequency point in the table is highlighted.
Step 4. Enter the frequency value you want using the numeric keys. Terminate it
using the unit menu keys which are presented to you.
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Step 5. Press the Tab —> key or Row Down menu key.
The next frequency point on the table is highlighted.
Enter the next frequency value by using the numeric key pad and the unit
termination keys.
Step 6. Repeat step 5 until your list is complete.
Step 7. Save the Frequency List to the NFA internal memory or to a diskette if
required using the File key. See “Saving a File” on page 41 for an
explanation of this.
NOTE
If you do not save the frequency list, you may lose the data. This depends on
your Power On/Preset condition. See “Defining the Power-On/Preset
Conditions” on page 232 for an explanation of these.
Creating a Frequency List from Swept Points
You can create a frequency list from the swept mode frequency and points
data.
To set the NFA to use the swept mode data:
Step 1. Press the Frequency/Points, More 1 of 2 menu keys.
Step 2. Press the Freq List, More 1 of 2 menu keys.
Step 3. Pressing the Fill menu key.
This clears the current frequency list and fills the list with the frequencies
generated by the sweep frequency mode.
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Setting the Measurement Frequencies
Selecting Fixed Frequency Mode
The fixed frequency mode is used when you want to make a measurement at
a single frequency. See “Making a Fixed Frequency Measurement” on
page 34 for more details of this mode.
NOTE
If you have not entered the noise source ENR data which you intend using
for the fixed frequency mode measurement, you need to specify a spot ENR
value and set the ENR mode to spot.
To set a fixed frequency:
Step 1. Press the Frequency/Points, Freq Mode menu keys.
Step 2. Press the Fixed menu key to set the frequency mode to Freq Mode(Fixed).
The Fixed Freq menu key is now available.
Step 3. Press the Fixed Freq menu key and enter the frequency value using the
numeric keys and the unit termination menu keys.
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Setting the Bandwidth and Averaging
Setting the Bandwidth and Averaging
Effect of Bandwidth and Averaging on Speed, Jitter, and
Measurement Accuracy
Jitter is a natural occurrence when measuring noise. To reduce jitter you
must increase the number of averages or increase the measurement
bandwidth.
If the bandwidth is reduced, you need to increase the number of averages to
maintain the same uncertainty.
The greater the number of averages chosen, the more accurate the
measurement, as this reduces jitter on the measurement. However, this has to
be considered against how long it takes to complete the measurement.
Therefore, there is a trade off between speed and the accuracy/uncertainty of
a measurement.
NOTE
On the N8972A model, the average mode menu key is unavailable. Point
mode averaging is used on this model.
Selecting a Bandwidth Value
The default bandwidth is 4MHz. To change the bandwidth value:
Step 1. Press the Averaging/Bandwidth key.
The current bandwidth is shown on the Bandwidth menu key.
Step 2. Press the Bandwidth menu key and select the bandwidth you want from the
list of available options.
NOTE
On the N8972A model, the bandwidth menu key is unavailable. The
bandwidth is fixed at 4MHz.
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Setting the Bandwidth and Averaging
Setting Averaging
Increased averaging reduces jitter and provides more accurate measurement
results. However, the measurement speed is sacrificed. The maximum
number of averages allowed is 999. The default value is 1 and this
equivalent to setting averaging to off.
Enabling
averaging
Averaging can be enabled by setting the Averaging(On). To disable
averaging set Averaging(Off)
Setting the Number of Averages
To set the number of averages you want:
Step 1. Press the Averaging/Bandwidth key, and then the Averages menu key.
Step 2. Enter the numeric value you want using the numeric key pad. Terminate it
with the Enter key.
Selecting the Averaging Mode
Averaging Mode can be set to Average Mode(Point) or
Average Mode(Sweep).
The difference between the averaging modes is:
•
In Point mode, the selected number of averages are measured at each
point before moving to the next measurement point in the sweep. The
measurement is complete after one sweep. The measurement restarts if
Sweep(Cont) mode is selected.
•
In Sweep mode, a single value is measured at each point in the sweep.
The result at each point is built up by averaging the results from multiple
sweeps until the selected number of averages have been measured at each
point. The average counter is incremented at the end of each sweep. If
Sweep(Sing) mode is selected the measurement is complete. If
Sweep(Cont) mode is selected the measurement continues, using
exponential averaging at each point.
Point averaging provides the fastest overall measurement time, as only one
sweep is required to obtain the averages at each measurement point.
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Setting the Bandwidth and Averaging
Sweep averaging takes longer overall, as multiple sweeps are required to
obtain the averages at all frequencies. However, initial results are obtained
quickly at all frequencies.
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Calibrating the Analyzer
Calibrating the Analyzer
To compensate for the noise contribution of the NFA, the associated cabling,
and so forth in the measurement path, a calibration is necessary. The
calibration measures the NFA’s noise contribution with no DUT (device
under test) in place. This correction is often referred to as the second stage
calibration. The correction is then applied to the measurement with the DUT
in place.
To perform calibration you need to enter the ENR values and set up the
frequency range, number of measurement points, the bandwidth, the
averaging, and measurement mode to be used during the measurement.
If you alter the frequency range after you have calibrated the NFA, it
changes NFA’s status to uncorrected or interpolated corrected states. You
need to recalibrate before you make another measurement to obtain as
accurate a measurement result as possible.
Corrected
measurements
You can make corrected measurements only at frequencies which are
covered by the current calibration. Attempting to make corrected
measurements at frequencies less than the lowest calibration frequency or
greater than the highest calibration frequency generates an error and
invalidates the calibration.
To proceed you must either:
•
perform a calibration over the desired measurement frequency range,
•
perform uncorrected measurements,
•
change the measurement frequency to that covered by the existing
calibration.
When to perform You must calibrate the NFA whenever:
calibration
• you power cycle the NFA
•
you Preset the NFA
•
you select a measurement frequency or frequency range outside the
currently calibrated range
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Calibrating the Analyzer
•
you change the fixed IF frequency in certain modes
•
you change frequency mode
•
you change measurement mode
•
there is a large temperature variation since the last calibration
•
the input signal level can no longer be measured using one of the
calibrated input attenuator ranges
•
when an invalid result is detected and the condition is indicated by a
“xx”. See “Indicating an Invalid Result” on page 102 for an explanation
of these condition.
Interpolated
results
You obtain interpolated results from the NFA whenever you change certain
measurement parameters, for example, the number of points.
Calibration
indicator
Whenever anything within the NFA changes to invalidate the current
calibration, the Corr field at the bottom right-hand corner of the display
switches to Uncorr. Figure 2-6 shows this indicator.
Figure 2-6
Corrected/Uncorrected indicator
Corrected/Uncorrected indicator
Interpolated
calibration
Whenever anything within the NFA changes to force the current calibration
to interpolate the measurement results, the white Corr field at the bottom
right-hand corner of the display switches to a yellow Corr.
For Agilent
8970B users
All the NFA models have more RF ranges than the Agilent 8970B and unlike
the Agilent 8970B, all of these ranges can be calibrated using a 15dB ENR
noise source without the need for external amplification.
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Calibrating the Analyzer
To perform a calibration
Step 1. Verify that the correct ENR table is loaded in the NFA, or input the ENR
values of the noise source into the NFA.
See “Entering Excess Noise Ratio (ENR) Data” on page 51 for more details.
Step 2. Configure the measurement parameters (frequency range, number of points,
bandwidth, averages, and measurement mode) you want to use for the
measurement.
Step 3. Connect the noise source output directly to the NFA input.
NOTE
If you are following this procedure using an N8974A or an N8975A models
care needs to be taken when connecting the precision 3.5 mm connector by
applying the correct torque. For an explanation of the connectors and
guidance on the correct torque values, see the Performance Verification and
Calibration Guide.
Figure 2-7
NFA Calibration with Normal Noise Source
Noise Source
NOTE
You may need to use connector adaptors to connect the noise source output
to the NFA input during calibration. The connectors you use need to be
included in the measurement. If you remove the connectors from the
measurement you need to apply Loss Compensation to compensate for any
loss caused by the connectors removal. See “Using Loss Compensation” on
page 119 for an explanation of this.
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Step 4. If required select an input attenuator range by pressing the Corr key and the
Input Cal menu key to set the minimum and maximum input attenuation.
See “Selecting the RF Input Attenuation Range” on page 78 for more details
on input attenuation.
Step 5. Press the Calibrate key twice to initiate the calibration.
The first time you press the key you are prompted to press it again. This
two-stroke key press feature prevents you from accidentally pressing
Calibrate and erasing the calibration data.
The NFA performs the calibration, displaying a percentage counter while
this is happening.
When the calibration is finished the calibration indicator changes from a
white Uncorr display to a white Corr display. Also the Corrected menu
key is now available to you. This allows you to make corrected or
uncorrected measurements by switch between Corrected(On) and
Corrected(Off) respectively.
NOTE
When performing a calibration only noise figure and effective temperature
result types are calculated by the NFA. If you wish to see the results during a
calibration you need to select either of these two result types to display them.
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Calibrating the Analyzer
Selecting the Input Attenuation Range
Selecting the RF Input Attenuation Range
When working in the RF frequency range of 10 MHz to 3.0 GHz, the NFA
has a default input attenuation range for calibration of 0dB to 20dB. In the
default mode the calibration takes 5 sweeps as 5 attenuator ranges need to be
calibrated. The greater the attenuator range selected, the greater the number
of calibration sweeps there are, hence, the longer the calibration routine.
When measuring a high-gain device you may need to increase the input
attenuation. If you do not know the gain of the DUT, you can perform
calibration using the default range, note what error codes are presented and
then calibrate again using increased attenuation value. The attenuation value
is indicated on the display as shown in Figure 2-8 and Figure 2-9. If the NFA
continues to display error codes, there is a need to add external attenuator
pads and correct for this attenuation using the Loss Compensation feature.
For an explanation of how to use the feature, see “Using Loss
Compensation” on page 119.
If an error message occurs while calibrating, you need to recalibrate. For a
complete list of error codes see Chapter 7 “Troubleshooting”.
To select the RF input attenuation:
Step 1. Press the Corr (Corrected) key.
Step 2. Press the Input Cal menu key and select the attenuation range you want
Step 3. Set the attenuator range using the Min RF Atten and Max RF Atten menu
keys, and select the attenuation values you want from the list.
Figure 2-8
N8972A and N8973A Attenuator Indicators
Invalid Indicator
78
Valid Indicator
Chapter 2
Making Basic Measurements
Calibrating the Analyzer
Figure 2-9
N8974A and N8975A Attenuator Indicators
Invalid Indicators
Valid Indicators
Invalid RF Indicator and Valid Microwave Indicator
Selecting Microwave Input Attenuation Range
The N8974A and N8975A models have a microwave frequency range.
When working in the microwave frequency range of 3.0 GHz to 26.5 GHz,
the NFA has a default input attenuation for calibration of 0 dB. Unlike the
RF attenuators, the microwave attenuators cannot autorange. Therefore there
is a risk of overdriving the instrument. In most cases 0 dB attenuation is
adequate. A guide to the input powers that each range can handle can be seen
in Table 2-1.
Table 2-1
Power Detection and Ranging
Attenuation
Maximum Input
Power
DUT Parameters
0 dB
−30 dBm
Combined NF and Gain of DUT
≤25 dB over full bandwidth
15 dB
−20 dBm
Combined NF and Gain of DUT
> 25 dB and ≤35 dB over full bandwidth
30 dB
−10 dBm
Combined NF and Gain of DUT
>35 dB and <45 dB over full bandwidth
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To select the microwave input attenuation:
Step 1. Press the Corr (Corrected) key.
Step 2. Press the Input Cal menu key and select the attenuation range you want
Step 3. Set the attenuator range using the Min mW Atten and Max mW Atten menu
keys, and select the attenuation values you want from the list.
Setting the Microwave Input Attenuation after a Calibration
The microwave attenuators cannot autorange. Hence, when making a
microwave measurement you must manually set the microwave input
attenuation to avoid overdriving the NFA. To set the microwave input
attenuation:
Step 1. Press the Sweep key.
Step 2. Press the Manual Meas, More 1 of 2 menu key.
Step 3. Press the Fixed mW Att menu key and select the attenuation range you
want.
Step 4. Press the More 2 of 2 menu key.
Step 5. Press the RF/mW Atten menu key to enable RF/mW Atten(Fixed).
NOTE
If you want to set the RF input attenuation, “Setting the Microwave Input
Attenuation after a Calibration” procedure can be applied to RF input
attenuation. The procedure is similar except you need to substitute
Fixed RF Att in Step 3.
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Displaying the Measurement Results
Displaying the Measurement Results
The NFA features a 17 cm color display and a comprehensive set of display
features to allow you to analyze the measurement results in detail, or quickly
obtain pass/fail indication.
The following display format features are available:
NOTE
•
Graph, Table or Meter mode display
•
Single or dual-graph display allowing any two available result types to be
displayed simultaneously
•
Zoom to display only one result graph on the display
•
Combine option to display two result types on the same graph
•
Markers for searching the trace
•
Display an active trace, a memory trace, or both
•
Save the current active trace data to memory
•
Switch the graticule on or off
•
Switch display annotation on or off
If the NFA’s display has been previously disabled in Remote mode, you need
to press the System (LOCAL) key to activate the display.
Selecting the Display Format
You can display the measurement results in either:
•
•
•
Graph format
Table format
Meter format
The default display provides a display of noise figure and gain on the
dual-graph display. The upper graph is noise figure and the lower graph is
gain.
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In all formats you can choose two result parameters you want to display.
To set the display format:
Step 1. Press the Format key.
Step 2. Press the Format menu key and select the Graph, Table or Meter menu key
to select the display mode you want. See Figure 2-10.
Figure 2-10
Format modes
Navigating Around the Display
Active Graph
The active graph is highlighted by a green border. Noise Figure is the active
graph by default.
NOTE
When in table or meter format the active measurement parameter title has a
green border around it.
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Figure 2-11
Dual-graph display
Changing the
Active Graph
To change the active graph, press the
key below the display. This
key allows you to set the upper or lower graph as the active graph.
NOTE
When in table or meter format the
Viewing the Full
Screen
You can fill the entire display and remove the menu keys, the active function
area annotation, and the display status line annotation from the display. Press
the Full Screen key to view the full screen. Pressing the Full Screen key
again returns it to the previous display. All other key presses are ignored
except: Zoom, Next Window, Save Trace, Help, Preset, Print, Power
Standby, and the Viewing Angle keys.
NOTE
The Full Screen key also functions in table or meter format.
Chapter 2
key changes the active parameter.
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Making Basic Measurements
Displaying the Measurement Results
Selecting Result Types to Display
You can choose to display any pair of measurement results in all of the
display format modes.
NOTE
You cannot display the same result type in both graphs. If you attempt this,
an error message Each result type selected must differ from
all others is displayed in the status line.
The measurement result types are as follows, with their units in parenthesis:
•
Noise Figure (dB or linear)
•
Gain (dB or linear)
•
Y Factor (dB or linear)
•
Teffective (Kelvin, K; Celsius, C; Fahrenheit, F)
•
Phot (dB or linear)
•
Pcold (dB or linear)
To specify which measurement results are displayed
Step 1. Select which measurement result is active using the
key.
The active measurement is highlighted by a green border.
Step 2. Press the Result key and select the result type that you want to display.
Step 3. Press the
key to make the other measurement result active.
Step 4. Press the Result key and select the result type you want to display.
NOTE
When you press the Scale key, the active measurement result’s scale menu
keys are shown.
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Graphical Features
Viewing a single graph
While in graph format mode, you can press the
key located below the
display and the active graph fills the display as a single graph, as shown in
Figure 2-12. Pressing the key again returns the display to dual-graph.
Figure 2-12
Displaying a single graph
NOTE
When in single graph mode, pressing the
single graph.
Chapter 2
key displays the other
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Making Basic Measurements
Displaying the Measurement Results
Combining two graphs on the same graph
You can combine the upper and lower graphs from a dual-graph display into
a single combined display. The default setting is Combined(Off) and the
graphs are not combined.
NOTE
When combining two graphs the Y-scale result limits are not re-scaled and
both graphs have their own Y-scale result limits.
To combine the two graphs:
Step 1. Press the Format key and ensure Format(Graph) is selected.
Step 2. Press the Combined(On) menu key to combine the two currently displayed
graphs on the same graph.
Figure 2-13
Typical display with two traces combined on the same graph
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Displaying the Current Data Trace and the Recalled Memory Trace
When a trace finishes its first complete sweep, the Data -> Memory menu
key becomes active.
To save a trace to memory, press the Data -> Memory menu key. After
pressing the Data -> Memory menu key, the Trace menu key becomes
active.
To view the saved trace, press the Trace menu key, followed by the Memory
menu key. The memory trace is presented in the display.
To view both the saved trace and the current active trace, press the Trace
menu key, followed by the Data & Memory menu key.
To view the current data trace only, press the Trace menu key, followed by
the Data menu key. This is the default setting.
NOTE
Pressing Autoscale does not re-scale a memory trace.
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Turning the Graticule On and Off
When Graticule(On) is set, the graticules are displayed on the screen. This is
the default setting. When Graticule(Off) is set the graticules are not
displayed on the screen.
To turn the graticule on or off:
Step 1. Press the Format key.
Step 2. Press the Graticule menu key to select the Graticule(Off) or Graticule(On) as
required.
Figure 2-14
Typical Graph with Graticule Switched Off
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Turning the Display Annotation On or Off
When Annotation(On) is set, the annotation is displayed on the screen. This
is the default setting. When Annotation(Off) is set the annotation is not
displayed on the screen.
To turn the annotation on or off:
Step 1. Press the Format key.
Step 2. Press the Annotation menu key to select Annotation(Off) or
Annotation(On) as required.
Figure 2-15
Typical Graph with Annotation Switched Off
NOTE
When Annotation(Off) is selected and limit lines are set to Test(On) the
limit line failure indicator is disabled.
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Setting the Scaling
You can set the result’s scale parameters in the active graph. To set the scale,
press the Scale key.
NOTE
To change the active graph, press the Result key and select another
measurement parameter’s menu key. Press the Scale key to set the scale of
the measurement parameter.
Figure 2-16
Typical Noise Figure Displayed on a Graph
You can set the scale for the measurement parameter or press the Autoscale
menu key. Pressing Autoscale selects the optimum values for Upper Limit,
Lower Limit, and Scale/Div.
NOTE
If limit lines are set to Display(On), and Autoscale is pressed or the scale is
changed, the limit lines may no longer appear in the display.
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NOTE
If a memory trace is set to display, and Autoscale is pressed or the scale is
changed, the memory trace may no longer appear in the display.
Setting Noise Figure Scale
NOTE
The following procedure can also be applied to other result types
To make Noise Figure the active screen and set up the noise figure
parameters use the following procedure.
Step 1. Press the Result key.
Step 2. Press the Noise Figure menu key.
Step 3. Press the Scale key.
Step 4. Press the Units menu key and select, either logarithmic ratio Units(dB) or
linear ratio Units(Linear).
Step 5. Press the Upper Limit menu key. Change the upper limit value using the
RPG or the numeric keys. Values are entered using the numeric keys, and
terminated using the Enter key if the units are dB. If your units are linear,
terminate them using the engineering multiplier menu keys presented.
Step 6. Press the Lower Limit menu key. Change the lower limit value using the
RPG or the numeric keys. Values are entered using the numeric keys, and
terminated using the Enter key if the units are dB. If your units are linear
terminate them using the engineering multiplier menu keys presented.
NOTE
The upper limit, lower limit, and scale per division values are coupled,
therefore changing one of these may affect the others.
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Step 7. Press the Scale/Div menu key. Change the scale per division value using the
RPG or the numeric keys. Values are entered using the numeric keys, and
terminated using the Enter key if the units are dB. If your units are linear
terminate them using the engineering multiplier menu keys presented.
Setting the Reference Level
NOTE
The reference level minimum and maximum limits are restricted to the
values of the upper and lower scale settings.
NOTE
The reference level is only visible when the Display Ref(On) is enabled.
Step 1. Press the Display Ref menu key if you want the reference level displayed in
the active graph. The default setting is Display Ref(Off). Set the
Display Ref(On) to switch the reference level on.
Step 2. Press the Ref Level menu key. Change the reference level value using the
RPG or the numeric keys. Values that are entered using the numeric keys are
terminated using the Enter key.
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Working with Markers
NOTE
The marker functions only apply when you are working in graph format.
Marker functions measure the frequency and measurement result by placing
a diamond-shaped marker at a point on the trace. The measurement result
displayed depends on the result type selected.
You can compare results by placing markers on a previously saved
(memory) trace and the current (data) trace and measuring the difference.
The NFA has four markers, Marker(1), Marker(2), Marker(3), and
Marker(4). The markers are coupled to both the lower graph trace and upper
graph trace.
Each marker can be enabled as a normal, delta, or band pair marker. The
active marker’s frequency is displayed in the active function area. The
enabled marker’s results are displayed in the annotation above the upper
graph where the measurement mode status is displayed when all the markers
are off.
Selecting Markers
To select a marker:
Step 1. Press the Marker key.
Step 2. Press the Marker menu key to select the marker of interest.
The active marker is identified by being underlined in the Marker menu key
label. See Figure 2-17.
Figure 2-17
The Active Marker is Underlined
Step 3. Press the State menu key and press the Normal menu key to highlight it.
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Figure 2-18
A Normal State Marker
A single coupled pair of markers are now placed on both traces. Turn the
RPG to place the markers at the point on the trace you want to measure or
use the numeric keys to enter the frequency of interest. The marker
frequency and measurement parameter are annotated above the graph. Its
frequency value is displayed in the active function area.
To turn an active To turn an active marker off, press the State menu key and press the Off
marker off
menu key. This also removes the marker annotation above the graph and the
marker frequency from active function area.
To change the
active marker
The default active marker setting is Marker(1). To change the active marker,
press the Marker menu key. This moves the active marker from Marker(1) to
Marker(2). Press it again and it moves the active marker from Marker(2) to
Marker(3). This process is repeated until it returns to the Marker(1).
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Figure 2-19
Four Normal State Markers
To Switch all the To switch all the markers off press Markers All Off. This turns off all the
Markers Off
markers and associated annotation.
Changing the Marker States
To use Delta
Markers
The State(Delta) menu key places a reference marker at the current position
of the active marker. The delta markers enable you to measure the difference
between the reference marker and the delta marker position on the trace.
Turn the RPG to place the delta marker to the point on the trace you want to
measure. The position of the reference marker remains fixed. The delta
marker has its frequency and measurement result value differences
annotated relative to the reference marker above the upper graph. Its actual
frequency value is displayed in the active function area. See Figure 2-20.
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Figure 2-20
The Delta Marker State enabled
To activate a Delta marker:
Step 1. Press the Marker key.
Step 2. Press the Marker menu key to select the marker of interest.
Step 3. Press the State menu key and press the Delta menu key to highlight it. Use
the RPG to move the Delta marker from the reference. The annotation
displays the difference.
To use Band Pair The State(Band Pair) menu key places two markers allowing you to choose
Markers
to move either the normal marker or the reference marker. This feature is
similar to the State(Delta) except you can choose to move either marker.
The position of the reference marker remains fixed until Band Pair(Normal)
menu key is pressed and the active marker becomes the fixed marker. This
can be altered by pressing the Band Pair(Ref) menu key to enable the
reference marker as the active marker. The active marker has its frequency
and measurement result value differences annotated above the graph. Its
actual frequency value is displayed in the active function area. See Figure
2-21.
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Figure 2-21
Band Pair with Reference Marker Enabled
To activate the Band Pair markers:
Step 1. Press the Marker key.
Step 2. Press the Marker menu key to select the marker of interest.
Step 3. Press the State menu key and press the State(Band Pair) menu key to
highlight it.
The Band Pair(Ref) and Band Pair(Normal) menu keys in the Band Pair
menu key is no longer disabled.
Step 4. Use the RPG to move the active marker from the reference. The annotation
displays the difference between the reference and the normal markers
position.
Step 5. Pressing the Band Pair menu key sets the Band Pair(Normal) as the fixed
marker allowing you to move the reference marker. Pressing the Band Pair
menu key again sets the Band Pair(Ref) as the fixed marker allowing you to
move the normal marker.
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Figure 2-22
Band Pair with Normal Marker Enabled
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Marking Memory Traces
Markers can be placed on a memory trace. See “Displaying the Current Data
Trace and the Recalled Memory Trace” on page 87 to obtain an explanation
on memory traces. The default setting is Trace(Data) where the marker is
placed on the active trace.
To place a marker on the recalled memory trace:
Step 1. Enable the Trace(Memory) menu key.
Step 2. Set the marker you want to use to Normal, Delta, or Band Pair.
The marker is placed on the memory trace. If Trace(Data&Memory) on the
format menu is enabled, switching between Trace(Data) and
Trace(Memory) switches the marker between the traces.
NOTE
If a marker is set to Trace(Memory) and the Memory trace is not displayed,
the marker and its annotation are not displayed.
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Searching with Markers
The Search menu key accesses a further menu which allows you to place an
active marker on the minimum and maximum points of a trace, while in
Normal or Delta state. When in Band Pair state you can search for the
Minimum Peak to Maximum Peak on the trace. You can set these to repeat
continuously, or by manually pressing the Find menu key as required.
NOTE
If you are searching continuously the markers have additional annotation
which identifies which marker is the minimum and the maximum. The
annotation is “∨” a minimum, “∧” a maximum. If you change the active
graph the annotation remains on the original graph.
Searching for
You need to have activated a Normal or Delta marker state to perform a
Min or Max point minimum or maximum search.
Figure 2-23
Typical Trace showing Maximum Point Found
To search for the maximum point:
Step 1. Press the Search menu key.
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Step 2. Press the Search Type menu key to select the Search Type(Max).
Step 3. Press the Find menu key.
The marker is now placed at the maximum point of the trace.
If you want to continuously find the maximum point on the trace, select
Continuous(On).
Searching for
Peak to Peak
points
You need to have activated a marker state to Band Pair to perform a Peak to
Peak search.
Figure 2-24
Peak to Peak Found
Step 1. Press the Search menu key.
Step 2. Press the Search Type menu key to select Pk-Pk.
Step 3. Press the Find menu key.
The markers are now on the maximum and minimum points of the trace.
If you want to continuously find the maximum and minimum points on the
trace, select Continuous(On).
The annotation displays the difference between the two points.
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Indicating an Invalid Result
Indicating an Invalid Result
When an invalid result is detected while in graph display format, the graph is
drawn at the top of the screen for the current measurement point and a
special marker indicator is displayed. Also in table and meter formats the
same special indicators are used to display an invalid result.
Several invalid result conditions may exist simultaneously. These conditions
are ranked in order of severity and only the most severe condition present is
displayed.
The ranking order is:
Table 2-2
Ranking Order
Ranking Order of Invalid Result Conditions
Invalid Result Condition
Marker Indicator
1
Hot power ≤ cold power
“==”
2
Corrected calculation not possible
“xx”
3
Measurement result calculation invalid
“--”
The ranked order 2 only occurs if a corrected measurement is requested and
either:
•
The input range used at this measurement point is not calibrated.
•
The input range is calibrated, but the calibration data is invalid at this
point.
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Indicating an Invalid Result
RF Input Over and Under Range Conditions
The NFA can detect when the RF input power is either too large for the
current input attenuation or too small for the current input attenuation. This
causes the RF input to over range or under range respectively.
These conditions are indicated beside a marker readout or table/meter entry
as RFO or RFU, for RF input over or under range respectively.
The over range condition could occur when the RF input power is so large
that even with the maximum input attenuation, the output power from the
input stage is still sufficiently large to create a non-linear response at
subsequent stages. This problem could be solved by using external
attenuation.
The under range condition could occur when, for example, the RF input
attenuation has been fixed at such a value that the level of input power, less
attenuation would not lead to compression of the subsequent stages. This
problem could be solved by either allowing the RF input attenuators to
autorange or choosing a lower value of fixed attenuation.
IF Input Over and Under Range Conditions
The NFA can detect when the power presented to the IF input section
detector is either too large for the current IF input attenuation or too small
for the current IF input attenuation. This causes the IF input section to over
range or IF input section to under range respectively.
These conditions are indicated beside a marker readout or table/meter entry
as IFO or IFU, for IF input section over or under range respectively.
The over range condition could occur when the RF attenuation is fixed at a
too small a value for the level of input power and subsequently the IF
section’s input power is so large that even with the maximum IF attenuation,
the power level at the IF detector is too large to obtain linear measurements.
This problem could be solved by using more RF input attenuation or
allowing the RF input attenuators to autorange.
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Example of a Basic Amplifier Measurement
Example of a Basic Amplifier Measurement
Noise figure measurements are made by measuring the output power of the
DUT for two different input noise power levels. Typically, the high power
input comes from a calibrated noise source, and the low power input uses the
noise power generated at ambient temperature.
This section uses a DUT to show how a basic noise figure measurement and
various basic operations are performed. The DUT used is a low noise
amplifier with a usable frequency range of 20 MHz to 3.0 GHz. The
specifications of interest to the example are listed in Table 2-3.
Table 2-3
The Example DUT Specifications
Frequency Range
Typical Gain
Minimum Gain
Typical Noise
Figure
20 MHz to 3 GHz.
19 dB
14 dB
3.8 dB
The example sets a frequency range of interest of 1.0 GHz to 2.0 GHz. The
purpose of the measurement is to verify the specified table results are as
stated over the frequency range of interest.
When you are making measurements, follow the procedure and change the
values to meet your needs.
NOTE
For these basic measurements confirm the NFA Meas Mode is in the default
setting. This status is displayed above the graphs as follows:.
•
DUT: Amplifier
•
System Downconverter: Off
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Calibrating the Noise Figure Analyzer
The first step is to calibrate the NFA to obtain the corrected measurement
you wish to make.
Step 1. Turn the instrument on by pressing On and wait for the power-up process to
complete.
NOTE
To obtain greater accuracy, it is recommended the NFA warm up for at least
one hour with Alignment(On). The default setting is Alignment(On)
Step 2. Press System, Power On/Preset, Preset (Factory) and press the green
Preset key to return the NFA to its factory-default state.
Step 3. Press ENR, ENR Mode(Table), Common Table(On), ENR Table to enter
the ENR values of the noise source.
In this example, a 346B noise source is used which has the following
Frequency/ENR pairs up to 2 GHz (covering the required frequency range of
1.0 GHz to 2.0 GHz):
Table 2-4
Example Noise Source ENR/Frequency values
Frequency
GHz
ENR
dB
.01
15.29
.10
15.39
1.0
15.17
2.0
15.10
Step 4. Press the Frequency/Points key to set the frequency parameters of the
measurement:
•
•
•
•
Freq Mode — Sweep
Start Freq — 1.0 GHz
Stop Freq — 2.0 GHz
Points — 15
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Step 5. Press the Averaging/Bandwidth key to set the bandwidth and averaging you
want.
This example uses the following settings:
•
Averaging — On
•
Averages — 5
•
Average Mode — Point
•
Bandwidth — 4 MHz
Step 6. Press Corr, Input Cal to set the minimum and maximum input attenuation, if
required.
This example uses the default minimum and maximum input attenuation of
Min RF Atten(0 dB) and Max RF Atten(20 dB), respectively.
Step 7. Connect the noise source input to the 28V OUTPUT port using a BNC cable,
and connect the output to the INPUT 50 W port as shown in Figure 2-25.
NOTE
When using the N8974A and N8975A models care must be taken to torque
the precision 3.5mm connector to the correct value. To find the correct value
of torque to apply, see the Performance Verification and Calibration Guide.
Figure 2-25
Calibration Setup with Normal Noise Source
Noise Source
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Step 8. Press the Calibrate key twice to calibrate the NFA.
Once you have set the frequency span, averaging, bandwidth, and calibrated;
a graph similar to Figure 2-26 is now displayed.
With calibration completed and no device under test inserted, both gain and
noise figure with Corrected(On) are near zero dB. This shows that the NFA
has removed the noise contribution from the measurement system. Since the
input is noise, there is some variation above and below zero.
Figure 2-26
Typical Graph after calibration is complete
Press the Format key to select Format menu key to Table. A result similar
to Figure 2-27 is now displayed. The expectation is 0 dB of noise figure and
gain. It may be better to view these results using table format mode.
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Figure 2-27
Typical Tabulated Results after Calibration
Making Measurements
To make noise figure measurements once calibration is complete:
Step 1. Disconnect the noise source from the 50Ω input of the NFA
Step 2. Connect the DUT to the 50Ω input of the NFA.
Step 3. Connect the noise source to the DUT as shown in Figure 2-28.
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Figure 2-28
Connecting the DUT to make a measurement
Noise Source
DUT
After the DUT and noise source are connected, the measurement result
appears on the NFA’s display. If it does not, press Restart. If you want to get
a continuous update ensure Sweep(Cont) is enabled. This is the default
setting.
A result similar to Figure 2-30 is now displayed.
Figure 2-29
Typical Tabulated Results after Measurement
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Step 4. Press the Format key to select Format menu key to Graph. A graphical
result similar to Figure 2-29 is now displayed.
Figure 2-30
Typical Graphical Results after Measurement
The results shown in Figure 2-29 and Figure 2-30 shows the DUT has an
average noise figure of 3.35 dB and a gain of 18.50 dB. The device under
test therefore meets its manufacturer’s specification over the frequency
range of interest.
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Advanced Features
This chapter describes how to use the Limit Lines and Loss Compensation
features on your Noise Figure Analyzer. It also covers how to make manual
measurements.
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What You will Find in this Chapter
What You will Find in this Chapter
This chapter covers:
•
Setting up Limit Lines and using them for pass/fail testing of the
measurements.
•
Using Loss Compensation and using this to correct for system losses in
cabling, switches, or connectors and so forth. Also, the use of S2P file
formats to create Loss Compensation Tables.
•
Making Manual Measurements.
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Setting up Limit Lines
Setting up Limit Lines
Limit lines can be set to mark lower or upper boundaries of the active traces
and they can also be set to notify you of a failure when a trace passes over a
limit line. Two limit lines can be applied to a single trace, for example,
allowing an upper and lower boundary limit to be specified.
The NFA features four independent Limit Lines. The Limit Line(1›) and
Limit Line(2›) are applied to the upper graph, and Limit Line(3fl) and
Limit Line(4fl) are associated with the lower graph.
To change the
Limit Line
The default limit line setting is Limit(1›). To change the active indicator,
press the Limit Line menu key. This moves the active indicator from
Limit Line(1›) to Limit Line(2›), press it again and it moves the active
indicator from Limit Line(2›) to Limit Line(3fl). This process is repeated
until it returns to the Limit Line(1›).
Setting the Type
of Limit Line
You can set the Limit Line to be an upper limit or lower limit and test the
trace against this limit line setting.
To set the limit line type, choose Type(Upper) if you want it to be above the
trace or Type(Lower) if you want it to be below the trace. Each of the four
limit line needs to be set up separately.
NOTE
There can be instances when you want to have two limit lines on a screen
configured as Upper or Lower type, where one limit line could be a tolerance
limit fail and the other an absolute limit fail.
Enabling Testing You can set the Limit Line to test against the trace. If a result fails testing it is
against a Limit
reported in the upper left hand corner of the display as shown in Figure 3-1.
Line
In table mode you also see the reported result failure.
To set the testing of the trace against the limit line, choose Test(On) if you
want the result reported or Test(Off) if you do not want the result reported.
Each of the four limit lines need to be set up separately.
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Setting up Limit Lines
NOTE
After a failure the LIMITS FAIL: indicator remains displayed until you
either switch Test(Off), change the limit line type, or press Restart.
Figure 3-1
Limit Fail Indicator
Limit Fail Indicator
To Display a
Limit Line
You can choose to display a Limit Line.
To display the limit line on the graph, choose Display(On). To not display
the limit line on the graph, choose Display(Off). Each of the four limit line
needs to be set up separately.
To Switch all the To switch all the Limit Lines off, press Limit Lines All Off. This
Limit Lines Off
simultaneously switches off all Limit Lines, regardless of what graph or
trace they are associated with and setting both Test(Off) and Display(Off).
NOTE
When a limit line is switched off the limit line data is not affected.
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Setting up Limit Lines
Creating a Limit Line
To set up limit lines, you need to specify the frequencies, the Y-axis value
and whether it is to be connected to the previous limit line point or not. The
limit line consists of a table of entries each of which is a
frequency-limit-connected group.
The Limit or Y-axis value is a dimensionless unit, hence you need to know
what Y-axis scale you are working in before you set this.
NOTE
When you change the result parameter, the Limit or Y-axis value is not
converted. This is due to the value being dimensionless.
To create a limit line:
Step 1. Press the Limit Lines key and select the limit line you want to create.
Step 2. Press the Editor menu key.
You are presented with a Limit Line table.
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Figure 3-2
Limit Line Table
Step 3. Enter the first Frequency value. Press the Tab key.
Step 4. Enter the first Limit or Y-axis unit value. Press the Tab key.
For a limit line value to be useful, it should be derived from the scale values
you are using to display the trace.
Step 5. Press the arrow key to change Connected to either Yes or No.
When Connected is set to Yes it connects the point to the previous point to
form a continuous line. To disconnect a point, set Connected to No, this
disconnects it from the previous point. Figure 3-3 shows the connections and
Figure 3-4 shows the graphical result with limit line Display(On).
NOTE
When the Limit Line is set to Test(On), and a trace crosses over the limit
line, the test is only performed between connected points. Also, if you are
making a fixed frequency measurement you only need to specify that
frequency value and the limit line can be tested on the single point.
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Step 6. Repeat this process until the limit line is defined. Limit line tables can have a
maximum of 201 entries.
The limit line is now defined. Press the Prev key or Limit Line key to return
to the limit line menu. When saving a limit line table you need to specify
which limit line number. See “Saving a File” on page 41.
For a greater explanation of table use, See “Working with Tables” on page
45.
NOTE
You can load a previously saved Limit Line table. However, you need to
specify which limit line number you want loaded. See “Loading a File” on
page 42.
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Figure 3-3
Typical Limit Line Connections in Table
Figure 3-4
Limit Line Connections Displayed
Limit Line Not Connected to Previous point
Connected Limit Line
Connected Limit Line
Trace
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Using Loss Compensation
Using Loss Compensation
You can configure the NFA to compensate for losses due to cabling,
connectors and temperature effects that occur in the measurement setup.
These can be between the Noise Source and the DUT, Before DUT, and/or
between the DUT and the NFA input, After DUT. Loss compensation can be
set either by specifying a single, fixed loss value which gets applied at all
frequencies, or using various loss values, specified in a table, applied across
the frequency span. In the table mode, linearly interpolated values are used
between each table entry. You can also specify a temperature value which is
applied at all frequencies.
You can also use S2P data file formats output from a Network Analyzer to
create Loss Compensation tables. The NFA converts the S2P file format to a
Loss Compensation table.
Examples where Loss Compensation is applied
This is important in cases such as:
1. Amplifiers with waveguide input, where a lossy waveguide-to-coax
adapter is needed.
2. Transistors, where input and output tuners are required.
3. Non-50Ω converters (such as TV tuners and amplifiers) where matching
pads or transformers are required.
4. Compensation for fixed attenuators used to improve SWR.
5. Double sideband measurement modification (of receivers and mixers) to
approximate single sideband results.
Configuring Fixed Loss Compensation
To configure fixed loss compensation follow the example below:
Step 1. Press the Loss Comp key.
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Step 2. Press the Setup menu key to access the Loss Compensation Setup
form, see Figure 3-5.
Figure 3-5
Loss Compensation Setup Form
Step 3. When configuring loss compensation before the DUT, use the Tab key to
navigate to the Before DUT field and set before DUT to fixed by selecting
the Fixed menu key to highlight it.
NOTE
A fixed loss compensation value cannot be entered or changed if the
Before DUT field or the After DUT field is not set to fixed. It is selected by
highlighting the Fixed menu key.
Step 4. To set the loss compensation value before the DUT, use the Tab key to
navigate to the Before DUT Fixed Value field and input the required value
for the loss occurring before the DUT, see Figure 3-6.
Enter a value using the numerical keypad and terminate it using the unit keys
presented to you, linear or dB.
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The lower limit is −100.000 dB, the upper limit is 100.000 dB, and the
default is 0.000 dB.
Step 5. When configuring loss compensation after the DUT, use the Tab key to
navigate to the After DUT field and set after DUT to fixed by selecting the
Fixed menu key to highlight it, see Figure 3-6.
Step 6. To set the loss compensation value after the DUT, use the Tab key to navigate
to the After DUT Fixed Value field and input the required value for the loss
occurring after the DUT.
Enter a value using the numerical keypad and terminate it using the unit keys
presented to you, linear or dB.
The lower limit is −100.000 dB, the upper limit is 100.000 dB and the
default is 0.000 dB.
Figure 3-6
Loss Compensation Setup Form with Fixed Selected
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Configuring Table Loss Compensation
To configure table loss compensation proceed as follows.
Step 1. Press the Loss Comp key.
Step 2. Press the Setup menu key to access the Loss Compensation Setup
form, see Figure 3-7.
Figure 3-7
Loss Compensation Setup Form
Step 3. When configuring table loss compensation before the DUT, use the Tab key
to navigate to the Before DUT field and select the Table menu key to
highlight it, see Figure 3-8.
The table loss compensation used is as specified in the Loss Compensation
Before DUT Table. See “Creating a Loss Compensation Table” on page 124.
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Step 4. When configuring table loss compensation after the DUT, use the Tab key to
navigate to the After DUT field and select the Table menu key to highlight it,
see Figure 3-8.
The table loss compensation used is as specified in the Loss Compensation
After DUT Table. See “Creating a Loss Compensation Table” on page 124.
Figure 3-8
Loss Compensation Setup Form with Table Selected
NOTE
You can load a previously saved Loss Compensation table. However, you
need to specify whether the Loss Compensation table is an After Table or a
Before Table. See “Loading a File” on page 42.
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Creating a Loss Compensation Table
Loss Compensation tables can have a maximum of 201 entries. To create a
loss compensation table proceed as follows:
NOTE
The example shows how to enter a Before DUT Table. If you want to enter
an After DUT Table follow the procedure, changing the Before Table key
presses to After Table key presses.
NOTE
If you want to enter new loss compensation data and there is previous loss
compensation data in the NFA, you can delete the previous data by pressing
Clear Table. An empty table is shown in Figure 3-9.
NOTE
The Loss Compensation table frequency limits in the Before DUT Table are
specified in terms of the DUT’s input frequencies and the After DUT Table
are specified in terms of the DUT’s output frequencies. This is important
when making frequency-converting DUT measurements or using a system
downconverter.
Step 1. Press the Loss Comp key, and the Before Table menu key.
A Loss Compensation Before DUT Table appears on the display
with the first loss frequency point in the table highlighted, see Figure 3-9.
The table editing and navigation menu items now appear. For details on
working with tables, see “Working with Tables” on page 45.
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Figure 3-9
An Empty Loss Compensation Table
Step 2. Enter the Loss Frequency value in the table using the numeric keys.
Terminate it using the unit menu keys.
Step 3. Press the Tab key to move the highlight to the Loss Value column and enter
the corresponding Loss Value.
When terminating the Loss Value you can use either dB or linear menu
keys. However, the result appears in the table in dB.
Step 4. Press the Tab key to move the highlight to the Loss Frequency column and
enter the next Loss Frequency Value.
Step 5. Repeat steps 2 to 4 until all the Loss Frequency and Loss Values you need
are entered.
Step 6. After completing the Loss Compensation table entries, press the Prev key or
Loss Comp key to return to the Loss Compensation menu.
Step 7. Once you have completed entering the Loss Compensation data, save the
Loss Compensation table using the File key.
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For details on saving files, See “Saving a File” on page 41.
NOTE
If you do not save the Loss Compensation table, you may lose the data. This
depends on your Power On/Preset condition. See “Defining the
Power-On/Preset Conditions” on page 232 for an explanation of these.
NOTE
You can insert the Loss Frequency/Loss Values in the Loss Compensation
Table entry in any order, as the NFA automatically sorts the table list into
ascending frequency order.
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Working with S2P, S1, and S2 File Formats
The S2P data file formats are described as frequency dependent linear
network parameters for 2 port components. The S2P file is output from a
Network Analyzer in the standard ASCII Touchstone S2P format. The
output format includes frequency values, S11, S21, S12, and S22 network
parameters. Not all these parameters are used by the NFA. The NFA uses the
frequency parameter which it reads as a loss frequency and the S21
parameter which it converts to a loss value.
NOTE
When saving S2P data format from a Network Analyzer you need to ensure
the data is saved in an ascending frequency order.
The S2P file format is loaded as a Loss Compensation table in the NFA,
either as a Before DUT or an After DUT Table. The NFA accepts any files
with the following extensions: S2P, S1, and S2.
The NFA can only load S2P file formats, it cannot save them. However, they
can be copied, deleted and renamed using the NFA’s file manager functions.
NOTE
If saving a previously loaded S2P file in the NFA, it is saved as a LOS file.
Loading an S2P, S1, or S2 File
To load a S2P format file into the NFA, the process is identical to loading a
loss compensation (LOS) file which has been stored previously on a diskette.
The choice needs to be made using the file manager’s list of available file
formats of LOS, S2P, S1, and S2.
Step 1. Insert the diskette into the floppy drive of the NFA.
For more details on loading files, see “Loading a File” on page 42.
Step 2. Press the File key.
Step 3. Press the Load menu key to access the file system.
Step 4. Press the Loss menu key.
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Step 5. Press either the Before Table or After Table menu key.
A list of available files on the [-A-] drive is displayed. Use the arrow keys
to access the appropriate file. The options have the following file extensions
S2P, S1, and S2
Step 6. Press the Enter key.
A Loading file prompt appears on the display and when this disappears
the file has been successfully loaded.
NOTE
To verify a successful loading of the S2P file as loss compensation table
data, view the Loss Compensation Before or After DUT Table form.
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Advanced Features
Using Loss Compensation
Setting Temperature of Loss
To set temperature of loss proceed as follows:
Step 1. Press the Loss Comp key.
Step 2. Press the Setup menu key to access the Loss Compensation Setup
form, see Figure 3-10.
Figure 3-10
Loss Compensation Setup Form with Temperature Selected
Step 3. To set the temperature value before the DUT, use the Tab key to navigate to
the Before Temperature field and input the required temperature of loss
value occurring before the DUT.
Enter a value using the numerical keypad and terminate it using the unit keys
presented to you, either in degrees K, C or F. Entries terminated using the C
or F menu keys are converted to K.
The lower limit is 0.0 K, the upper limit is 29,650,000.0 K and the default is
0.0 K.
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Using Loss Compensation
Step 4. To set the temperature value after the DUT, use the Tab key to navigate to
the After Temperature field and input the required temperature of loss value
occurring after the DUT.
Enter a value using the numerical keypad and terminate it using the unit keys
presented to you, either in degrees K, C or F. Entries terminated using the C
or F menu keys are converted to K.
The lower limit is 0.0 K, the upper limit is 29,650,000.0 K and the default is
0.0 K.
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Advanced Features
Making Manual Measurements
Making Manual Measurements
This feature is for making manual measurements with a hot/cold noise
source. It is primarily for users who do not use SNS or 346 Series noise
sources. These measurements are more difficult and slower than those made
automatically using a Noise Source with the NFA. The technique can be
applied using either a normal or SNS noise source to make Phot and Pcold
measurements by turning the noise source on and off.
The measurement is similar to one made using a Noise Source, except that a
hot source and a cold source must be physically connected for each noise
power reading. The difficulty in working with a cold source, for example,
liquid nitrogen, is in correcting for temperature gradients, condensation, and
so forth. This can introduce errors unless the measurement is very carefully
performed. If a normal noise source is used it can act as the hot/cold source.
The Noise Source is turned on or off by the appropriate Noise Source(On)
and Noise Source(Off), for example, Noise Source(On) provides Phot.
The following paragraphs give a step-by-step procedure for making the
measurement. Several steps are required for measurements at each
frequency point.
NOTE
The N8972A and the N8973A models do not have microwave hardware
installed and the menu keys are also different. Hence, in the following
procedures the RF/mW Att menu key should be referred to as the RF Att
menu key. Also the Fixed mW Att menu key is unavailable.
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Making Manual Measurements
Four important details you need to note when making manual
measurements:
1. A stable reading must be stored in the NFA memory before any change is
made to the physical connections.
A reading is stored by pressing the Accept menu key in the sequence
before changing connections.
2. The DUT must first be connected to the measurement system and then
the NFA’s input attenuators set. The input attenuators must be fixed for
the entire manual measurement by selecting either RF/mW Att(Hold) or
RF/mW Att(Fixed). When using the fixed mode the fixed attenuator
values are specified using the Fixed RF Att/Fixed mW Att menu keys.
3. The IF attenuators must be allowed to autorange between calibration and
measurement.
4. The IF attenuators must be held fixed for both calibration readings (noise
source on and off) and also for both measurement readings (noise source
on and off) by selecting either IF Att(Hold) or IF Att(Fixed). When using
the fixed IF mode the fixed IF attenuator value is specified using the
Fixed IF Att menu key.
NOTE
When calibrating a series of frequency points and an error is made on one of
the points, you need to start calibrating the series of frequency points again.
Press the Calibrate key to reset the calibration.
NOTE
When measuring a series of frequency points and an error is made on one of
the points, you need to start measuring the series of frequency points again.
Press the Restart key to reset the measurement.
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Advanced Features
Making Manual Measurements
Figure 3-11
Manual Measurement Display in Meter Format
Manual Measurements Procedure
NOTE
Between each stage of this procedure, ensure you wait until the data invalid
indicator has disappeared before you proceed.
The steps of a typical measurement are as follows:
Step 1. Find and hold RF/μW attenuators.
1. Connect the hot source, Th, to the DUT input, and the DUT output to the
NFA.
2. Press Noise Source(On) to measure noise power with the source at Th.
3. Press RF/mW Att(Hold) to hold RF attenuators for the entire
measurement.
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Making Manual Measurements
Step 2. Calibrate.
1. Remove the DUT and connect the noise source to the NFA
2. Press Calibration (On) to calibrate with noise source at Phot.
3. Press IF Att(Hold) to hold the IF attenuators fixed at the new value or use
the previously defined IF Att(Fixed) value.
4. Press Accept to store the Phot calibration reading.
5. Press Noise Source(Off) to select the Pcold calibration reading.
6. Press Accept to store the Pcold calibration reading.
Step 3. Measure.
1. Press Calibration (Off).
2. Connect Noise Source to the DUT and the DUT to the NFA.
3. Press Noise Source(On) to select the Phot reading.
4. Press IF Att(Auto) to allow the IF attenuators to autorange.
5. Press IF Att(Hold) to hold the IF attenuators fixed at the new value or use
the previously defined IF Att(Fixed) value.
6. Press Accept to store Phot measurement result.
7. Press Noise Source(Off) and press Accept to store Pcold measurement.
NOTE
If you have set up to measure a number of points over a frequency range.
You need to change the point number by pressing the Point menu key and
entering the point number and repeat the procedure from the next
measurement point. Repeat this until all the points have been measured.
The points need not be measured sequentially.
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4
Making Extended Frequency
Measurements
This chapter describes how to make measurements outside the baseband
frequency range of your Noise Figure Analyzer.
135
Making Extended Frequency Measurements
What You will Find in this Chapter
What You will Find in this Chapter
This chapter covers:
•
Overview of Configuring Extended Frequency Measurements
•
An overview of the Measurement Modes
•
Comparison of the 8970B and the NFA Series Measurement Modes
•
Choosing and Setting Up the Local Oscillator
•
Connecting the System
•
A description of Measuring a Frequency-Converting DUT
•
Making Frequency-Converting DUT Measurements using examples
•
A description of Measurements with a System Downconverter
•
Making System Downconverter Measurements using examples
•
Frequency Restrictions
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Making Extended Frequency Measurements
Overview of Configuring Extended Frequency Measurements
Overview of Configuring Extended Frequency
Measurements
Configuring extended frequency measurements involves four steps.
Step 1. Press the System key and configure the measurement system parameters as
required using the GPIB and External LO menu items.
Table 4-1
System Parameters
Parameter
Description
NFA Address
This sets the NFA’s GPIB address.
Valid addresses are from 0 to 30.
The default address is 8.
External LO Address
This sets the GPIB address of the
External LO attached to the LO GPIB
port.
Valid addresses are from 0 to 30.
The default address is 19.
LO GPIB Address
This sets the address through which
other devices, attached to the LO GPIB,
communicate with the NFA.
Valid addresses are from 0 to 30.
The default address is 8.
Command Set
This sets the External LO command
language. The default setting is
Command Set(SCPI) to operate a SCPI
compliant LO. Command Set(Custom)
is used when the External LO is not
SCPI compliant and operated using the
custom command strings.
LO Commands
This accesses the External LO
Commands Form. The form is used to
enter the commands used to control a
non-SCPI-compliant External LO.
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Making Extended Frequency Measurements
Overview of Configuring Extended Frequency Measurements
Table 4-1
System Parameters
Parameter
Description
Settling Time
This sets the settling time of the
External LO. This is used as a settling
period after the External LO frequency
is changed.
Min and Max Frequency
This sets the minimum and maximum
frequencies of the External LO.
Multiplier
This sets the multiplier value of the
External LO frequency.
Step 2. Press the Meas Mode key to configure the measurement mode of the Noise
Figure Analyzer.
For more details on the available measurement modes, see “Measurement
Modes” on page 139.
Step 3. Press the Mode Setup key to configure the measurement mode parameters
for the specific measurement mode you have selected.
Step 4. Configure the measurement (measurement frequency range, number of
measurement points and averages and so forth) using the Frequency/Points
and Averaging/Bandwidth keys.
For more details on configuring measurements, including calibration, see
Chapter 2 , “Making Basic Measurements,” on page 49.
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Making Extended Frequency Measurements
Measurement Modes
Measurement Modes
Available modes The Noise Figure Analyzer offers the following measurement modes
through the Meas Mode key on the front panel:
NOTE
•
The DUT is an amplifier-type device with no frequency conversion. This
is the basic measurement mode where the measurement frequency is
within the NFA’s frequency range. It is described in “Example of a Basic
Amplifier Measurement” on page 104.
•
The DUT is an amplifier-type device with frequency downconversion
occurring in the measurement test setup (system downconversion). The
LO can be either fixed or variable in this case.
•
The DUT is a frequency downconverter (that is, frequency
downconversion occurs in the DUT itself and not in the measurement test
setup). The LO can be fixed or variable.
•
The DUT is a frequency upconverter (that is, frequency up conversion
occurs in the DUT itself and not in the measurement test setup). The LO
can be fixed or variable.
The Amplifier measurement mode is for any DUT that does not perform
frequency conversion and includes amplifiers, filters, attenuators and so
forth.
Noise figure measurements involving mixers are necessary when:
•
The frequency conversion is part of the DUT. For example, the DUT is a
mixer or a receiver.
•
The frequency conversion is part of the measurement test set-up. The
DUT is to be measured at a higher frequency than the NFA’s frequency
range covers, hence an external mixer and local oscillator are added to
the measurement test set-up to convert this frequency to a frequency
within the NFA's range.
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Making Extended Frequency Measurements
Measurement Modes
The NFA can make a single frequency conversion, either in the DUT, or as
an added System Downconverter, which configures the NFA as a
frequency range extender. The NFA can also control an LO source remotely
using the SCPI commands or the custom commands. Under this control the
LO can be swept.
Basic Measurement — No Frequency Conversion
The basic measurement setup is shown in Figure 4-1, allowing you to
compare more complex setups with it.
Figure 4-1
Basic Noise Figure Measurement — No Frequency Conversion
Calibration Setup
Noise Source
Measurement Setup
Noise Source
DUT
When an uncorrected measurement is performed, the result is the measured
Noise Figure of all of the components after the noise source. When the
calibration setup is connected and the calibration performed, the NFA
measures its own noise figure and the connection set up. When a corrected
measurement is performed, the contribution of the calibration setup is
removed from the uncorrected result, giving a corrected measurement of the
DUT only.
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Measurement Modes
For these measurements the NFA mode is set to
DUT
Amplifier
System Downconverter
Off
NOTE
The RF input section on all NFA models has a built-in 3.0 GHz Low Pass
Filter. This filter needs to accounted for when planning your filter
requirements during calibration and measurement.
NOTE
On the N8974A and the N8975A models the microwave input section has no
filtering. This needs to accounted for when planning your filter requirements
for calibration and measurement. This is also important when making
measurements which cross over the 3.0 GHz switch.
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Making Extended Frequency Measurements
Measurement Modes
Frequency Down-converting DUT
In this mode, the DUT contains a frequency down-converting device, for
example, a mixer or receiver.
There are two modes to choose from:
1. A variable frequency LO and fixed IF.
Making this measurement, the NFA remains locked at one frequency and
the LO sweeps.
2. A fixed frequency LO and variable IF.
Making this measurement, the LO remains locked at one frequency and
the NFA sweeps.
NOTE
Filtering is needed to remove the unwanted sideband when making
single-sideband measurements in both modes. Ideally these filters should be
included in the calibration path and measurement path. However, if it is not
in the path, you can enter loss compensation to account for any additional
error.
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Making Extended Frequency Measurements
Measurement Modes
Fixed IF Variable LO (8970B Mode 1.3)
This is an overview of the key presses needed to set up the mode. See
“Frequency Restrictions” on page 207, for the restrictions applicable to this
mode. See “Making Frequency-Converting DUT Measurements” on
page 172 for an example of this mode. This shows a procedure for making
an LSB, Fixed IF and Variable LO measurement. However, you need to
change the settings and apply the appropriate filtering. For greater detail on
this see “Measuring a Frequency-Converting DUT” on page 159.
In the Measurement Mode Form set the following:
DUT
Downconv
System Downconverter
No Access
LO Mode
Variable
In the Mode Setup Form set the following:
NOTE
IF Frequency
Enter a value
Sideband
LSB, USB or DSB
LO Control
On
External LO Power Level
Enter value and
terminate using either
dBm or W
The External LO Power Level is displayed on the NFA as dBm.
In the Frequency menu, frequencies are specified as RF (input to DUT)
frequencies.
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Making Extended Frequency Measurements
Measurement Modes
Variable IF Fixed LO (8970B Mode 1.4)
These are an overview of the key presses needed to set up the mode. See
“Frequency Restrictions” on page 207, for the restrictions applicable to this
mode. See “Making Frequency-Converting DUT Measurements” on
page 172 for an example of this mode. This shows how to make an LSB,
Fixed IF and Variable LO measurement. However, you need to change the
settings and apply the appropriate filtering. For greater detail on this see
“Measuring a Frequency-Converting DUT” on page 159.
In the Measurement Mode Form set the following:
DUT
Downconv
System Downconverter
No Access
LO Mode
Fixed
In the Mode Setup Form set the following:
NOTE
LO Frequency
Enter a value
Sideband
LSB, USB or DSB
LO Control
Off or On
External LO Power Level
Enter value and
terminate using either
dBm or W
The External LO Power Level is displayed on the NFA as dBm.
In the Frequency menu, frequencies are specified as IF (output from DUT)
frequencies.
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Making Extended Frequency Measurements
Measurement Modes
Frequency Up-converting DUT
In this mode, the DUT contains a frequency up-converting device, for
example, a transmitter.
There are two modes to choose from:
1. A variable frequency LO and fixed IF.
Making this measurement, the NFA remains locked at one frequency and
the LO sweeps.
2. A fixed frequency LO and variable IF.
Making this measurement, the LO remains locked at one frequency and
the NFA sweeps.
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Making Extended Frequency Measurements
Measurement Modes
Fixed IF Variable LO (8970B Mode 1.3 with SUM Sideband)
These are an overview of the key presses needed to setup using this mode.
See “Frequency Restrictions” on page 207, for the restrictions applicable to
this mode. See “Making Frequency-Converting DUT Measurements” on
page 172 for an example of this mode. This shows a procedure how to make
an LSB, Fixed IF and Variable LO measurement. However, you need to
change the settings and apply the appropriate filtering. For greater detail on
this see “Measuring a Frequency-Converting DUT” on page 159. In this
mode, the DSB measurement is not allowed.
In the Measurement Mode Form set the following:
DUT
Upconv
System Downconverter
No Access
LO Mode
Variable
In the Mode Setup Form set the following:
NOTE
IF Frequency
Enter a value
Sideband
LSB or USB
LO Control
On
External LO Power Level
Enter value and
terminate using either
dBm or W
The External LO Power Level is displayed on the NFA as dBm.
In the Frequency menu, frequencies are specified as RF (input to DUT)
frequencies.
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Making Extended Frequency Measurements
Measurement Modes
Variable IF Fixed LO (8970B Mode 1.4 with SUM Sideband)
These are an overview of the key presses needed to set up using this mode.
See “Frequency Restrictions” on page 207, for the restrictions applicable to
this mode. See “Making Frequency-Converting DUT Measurements” on
page 172 for an example of this mode. This shows a procedure how to make
an LSB, Fixed IF and Variable LO measurement. However, you need to
change the settings and apply the appropriate filtering. For greater detail on
this see “Measuring a Frequency-Converting DUT” on page 159. In this
mode, the DSB measurement is not allowed.
In the Measurement Mode Form set the following:
DUT
Upconverter
System Downconverter
No Access
LO Mode
Fixed
In the Mode Setup Form set the following:
NOTE
LO Frequency
Enter a value
Sideband
LSB or USB
LO Control
Off or On
External LO Power Level
Enter value and
terminate using either
dBm or W
The External LO Power Level is displayed on the NFA as dBm.
In the Frequency menu, frequencies are specified as IF (output from DUT)
frequencies.
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Making Extended Frequency Measurements
Measurement Modes
System Downconverter
The DUT is a non-frequency converting device, for example an amplifier or
filter, and its frequency is higher than the NFA’s measurement range.
Frequency down-conversion is required within the measurement system,
using a mixer, external to the DUT, to convert the signal of interest to the
frequency range of the NFA.
There are two modes to choose from:
1. A variable frequency LO and fixed IF.
Making this measurement, the NFA remains locked at one frequency and
the LO sweeps.
2. A fixed frequency LO and variable IF.
Making this measurement, the LO remains locked at one frequency and
the NFA sweeps.
NOTE
Filtering is needed to remove the unwanted sideband when making
single-sideband measurements in both modes. Ideally any filtering is
included in the calibration path and measurement path. However, if it is not
in the path, you can enter loss compensation to account for any additional
error.
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Making Extended Frequency Measurements
Measurement Modes
Fixed IF Variable LO (8970B Mode 1.1)
These are an overview of the key presses needed to set up using this mode.
See “Frequency Restrictions” on page 207, for the restrictions applicable to
this mode. See “Making System Downconverter Measurements” on
page 194 for an example of this mode. This shows a procedure how to make
a DSB, Fixed IF and Variable LO measurement. However, you need to
change the settings and apply the appropriate filtering. For greater detail on
this see “Measurements with a System Downconverter” on page 184.
In the Measurement Mode Form set the following:
DUT
Amplifier
System Downconverter
On
LO Mode
Variable
In the Mode Setup Form set the following:
NOTE
IF Frequency
Enter a value
Sideband
LSB, USB or DSB
LO Control
On
External LO Power Level
Enter value and
terminate using either
dBm or W
The External LO Power Level is displayed on the NFA as dBm.
In the Frequency menu, frequencies are specified as RF (input to DUT)
frequencies.
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Making Extended Frequency Measurements
Measurement Modes
Variable IF Fixed LO (8970B Mode 1.2)
These are an overview of the key presses needed to set up using this mode.
See “Frequency Restrictions” on page 207, for the restrictions applicable to
this mode. See “Making System Downconverter Measurements” on
page 194 for an example of this mode. In this mode, a DSB measurement is
not allowed. This shows a procedure how to make a DSB, Fixed IF and
Variable LO measurement. However, you need to change the settings and
apply the appropriate filtering. For greater detail on this see “Measurements
with a System Downconverter” on page 184.
In the Measurement Mode Form set the following:
DUT
Amplifier
System Downconverter
On
LO Mode
Fixed
In the Mode Setup Form set the following:
NOTE
LO Frequency
Enter a value
Sideband
LSB or USB
LO Control
Off or On
External LO Power Level
Enter value and
terminate using either
dBm or W
The External LO Power Level is displayed on the NFA as dBm.
In the Frequency menu, frequencies are specified as RF (input to DUT)
frequencies.
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Making Extended Frequency Measurements
Comparison of the 8970B and the NFA Series Measurement Modes
Comparison of the 8970B and the NFA Series
Measurement Modes
Table 4-2 is to assist 8970B users map the 8970B measurement modes to the
NFA Series measurement modes.
Table 4-2
8970B Mode Comparison
8970B
NFA Series
Mode 1.1: Swept LO
System Downconverter
Fixed IF Variable LO
Mode 1.2: Fixed LO
System Downconverter
Variable IF Fixed LO
Mode 1.3: Swept LO
Downconverting
Fixed IF Variable LO
Mode 1.4: Fixed LO
Downconverting
Variable IF Fixed LO
Mode 1.3 with SUM Sideband: Swept LO
Upconverting
Fixed IF Variable LO, USB
Mode 1.4 with SUM Sideband: Fixed LO
Upconverting
Variable IF Fixed LO, USB
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Making Extended Frequency Measurements
Choosing and Setting Up the Local Oscillator
Choosing and Setting Up the Local Oscillator
Selecting a Local Oscillator for Extended Frequency
measurements with the NFA
Because of reciprocal mixing, noise components in the LO are converted
into the IF band applied to the NFA. This converted LO noise causes the
measured noise figure to be higher than the actual noise figure of the mixer.
If the mixer is to be used with a particular LO in its final application, its
noise figure should be measured with that LO. The measurement then gives
the actual noise figure of the extended frequency device - LO combination in
the final system.
For testing of extended frequency measurements, the LO must have a low
noise floor over frequencies equal to the LO ± IF.
Effect of high LO spurious signals and noise on mixer measurements
with low L-to-I rejection.
The LO’s spurious level also has to be low. At frequencies where there is a
high spurious signal the noise figure measured will have a peak at that IF.
For example, ideally the LO’s noise, including spurious, needs to be below
-90 dBm. If a mixer has higher isolation, then the LO’s noise can be higher
since the mixer will be better able to reject the LO’s noise.
This is especially necessary if the mixer has a poor balance, or L-to-I
isolation. With low isolation, the mixer is more likely to pass the LO noise
through and thus increase the measured noise figure.
NOTE
L-to-I rejection is the mixers ability to reject the LO’s spurious signals and
not allow them to pass through to the IF output.
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Making Extended Frequency Measurements
Choosing and Setting Up the Local Oscillator
Selecting a Local Oscillator for the NFA
Here are several criteria that must be met when choosing the LO:
1. It should have a frequency range appropriate to the DUT’s frequency
range, IF range, and sideband chosen.
2. It should be controllable over GPIB if variable LO measurements are to
be made.
3. It should have sufficient power to drive mixers (typically, +7 dBm)
4. It should have excellent frequency accuracy and repeatability (typically,
the same as the NFA you are using.)
The last point, frequency accuracy, deserves further comment. There are
three frequency-dependent components in an NFA measurement that must
all be aligned to make an accurate measurement at the IF. The need for
frequency accuracy is the main reason for recommending a synthesized
source for the LO, such as the Agilent 83712B Synthesized CW Generator.
Other LOs may be used, but should be tested to determine that their noise is
sufficiently low, as LO noise can cause a increase in noise figure for the
mixer/LO combination, and calibration of the system may not be possible. A
broadband, high gain amplifier at the LO output usually generates
unacceptable noise. This is almost always the case when a heterodyne-type
sweep oscillator or signal generator is used.
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Making Extended Frequency Measurements
Choosing and Setting Up the Local Oscillator
Setting up the NFA to drive the Local Oscillator
The following procedures are general to all the measurement mode settings.
These can be done independently of setting up the measurement.
•
Setting the External LO address
•
Setting the Minimum and Maximum LO Frequencies
•
Setting the Settling Time
Setting the External LO address
Step 1. Press the System key, the GPIB menu key.
The System GPIB Form appears on the display.
Step 2. Using the Tab key, highlight the External LO Address field, Figure 4-2
shows the form and the selected address. Set the External LO Address using
the numeric keypad and terminate it using the Enter key.
Figure 4-2
External LO Address
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Making Extended Frequency Measurements
Choosing and Setting Up the Local Oscillator
NOTE
If an error message GPIB Error, Write command timeout appears in
the NFA’s display status line, this indicates the external LO cannot be written
to. The problem is most likely one of the following:
•
The GPIB cable is either not attached or is not making proper contact.
•
The external LO is not turned on.
•
The NFA has the wrong address for the external LO.
If the NFA does not appear to be controlling the LO as described above,
check your setup to make sure all connections are properly made. Also
check for any bad connections or cables and that the LO is working properly.
Setting the Minimum and Maximum LO Frequencies
Step 1. Press the System key, the External LO menu key.
Step 2. Press the Min Freq menu key and enter the minimum frequency value.
Using the numeric keypad, terminate it using the unit menu keys, or use the
RPG and rotate it to the required value. Set the External LO to have a
minimum frequency equivalent to the LO you are using. The default value is
10 MHz.
Step 3. Press the Max Freq menu key and enter the maximum frequency value.
Using the numeric keypad, terminate it using the unit menu keys, or use the
RPG and rotate it to the required value. Set the External LO to have a
maximum frequency equivalent to the LO you are using. The default value is
40.0 GHz.
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Making Extended Frequency Measurements
Choosing and Setting Up the Local Oscillator
Figure 4-3
Setting Maximum and Minimum Frequencies and Settling Time and
Multiplier of the External LO
Setting the Settling Time
Step 1. Press the System key, the External LO menu key.
Step 2. Press the Settling Time menu key and enter the Settling Time value.
Using the numeric keypad, terminate it using the unit menu keys, or use the
front panel knob and rotate it to the required value. The default value is
100 mS.
Setting the Multiplier
Step 1. Press the System key, the External LO menu key.
Step 2. Press the Multiplier menu key and enter the multiplier value.
Using the numeric keypad, terminate it using the Enter key, or use the front
panel knob and rotate it to the required value. The default value is 1. The
maximum value is 1000000000.
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Connecting the System
Connecting the System
Figure 4-4 and Figure 4-5 show the connection diagram options you can use
to calibrate the NFA and after calibration, to measure a DUT, whether it is a
down-converter mixer, up-converter mixer, amplifier, or filter. It does not
show where to place a filter to remove any unwanted sideband or input
noise.
Setting Up the Noise Figure Analyzer
NOTE
You may connect the 10 MHz timebase frequency reference. Hence, the
NFA and the LO are locked at the same frequency reference. This can be
done from the NFA’s 10 MHz Ref Out to the LO’s 10 MHz Ref In or the
LO’s 10 MHz Ref Out to the NFA’s 10 MHz Ref In. It can also be provided
by an external reference. Ideally use the best standard reference available.
To connect the NFA to make measurements.
Step 1. Connect a GPIB cable between the NFA’s LO GPIB rear panel connector
and the Local Oscillator’s GPIB connector.
Step 2. Turn on both instruments and press the Preset key to return the NFA to a
known state.
The NFA can control the Local Oscillator, over its General Purpose Interface
Bus (LO GPIB) without the need for an external controller. The NFA does
not send LO controlling commands over it’s main GPIB. LO control is only
done over it’s LO GPIB.
Step 3. Enter the ENR values in to the NFA. See “Entering Excess Noise Ratio
(ENR) Data” on page 51 for the procedures to do this.
Step 4. Follow the procedure to calibrate the system, and measure the DUT, in the
mode to suit your needs.
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Connecting the System
Figure 4-4
System Downconverter Mode
LO
LO GPIB
Calibration Setup
Noise Source
LO
Measurement Setup
LO GPIB
Noise Source
DUT
Figure 4-5
Frequency Converting DUT Measurement Modes
Calibration Setup
Noise Source
LO
LO GPIB Control
Measurement Setup
Noise Source
DUT
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Measuring a Frequency-Converting DUT
Figure 4-6
Frequency Converting DUT Measurement Modes
Calibration Setup
Noise Source
LO
LO GPIB Control
Measurement Setup
Noise Source
DUT
In this mode, the DUT has frequency conversion in the measurement setup.
However, there is no frequency conversion in the calibration setup, this is
shown in Figure 4-6. The purpose of the calibration setup is to allow the
NFA to measure its own noise figure and sensitivity with the noise source.
This must be performed across the frequency range the NFA will tune over
in the measurement setup. When the measurement is made, the NFA
calculates the input frequency to the DUT, and using the appropriate values
from the noise source ENR table, interpolating as necessary, measures the
DUT.
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To allow the frequencies in the measurement setup to be calculated, the
frequency parameters for the measurement are entered into the NFA. There
are two possible sweep options:
1. The DUT LO is swept and the NFA is set to a fixed IF for the DUT.
2. The DUT LO is fixed and the NFA tuned frequency is swept.
If the DUT includes a fixed LO, then only option two is possible. If the DUT
uses an external LO, then either option is possible. The frequency
parameters for the measurement are entered into the NFA, hence it is
convenient to allow the NFA to perform all the frequency calculations and
control the LO.
For these measurements the NFA mode is set to
•
NOTE
DUT: Upconv or Downconv
The Upconverter and Downconverter modes include any DUT performing
frequency conversion, whether a simple single mixer or a complex receiver
structure.
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Sidebands and Images
For any measurement involving frequency conversion, you need to consider
the exact frequency ranges involved, and make decisions about the filtering
requirements for the specific measurement. For example, there may be
several different methods of measuring a mixer, and the method chosen may
be set by the choice of available filters.
Figure 4-7
Sidebands and Images
Amplitude
Fusb-Flo
mixing
FLO
Flo-Flsb
mixing
Broadband Noise
NFA Input
Band
Frequency
LSB Input
USB Input
Simple, ideal, mixers output signals on both the sum and difference of their
RF and LO frequencies. Hence, for a fixed output frequency and a fixed LO
frequency, there are two different input frequencies that are converted to the
output frequency. This is shown in Figure 4-7.
The noise sources used in noise figure measurements are broad-band, hence,
there is a probability that noise will be presented to a simple mixer in both
the upper and lower input frequency bands that are converted into the same
IF output band that the NFA is tuned to. The NFA receives mixer-created
noise from the two frequency bands superimposed. The noise is random,
hence the two power levels combine by simple addition. Similarly, the NFA
receives noise-source-created noise from the two frequency bands combined
as added power. Any measurement where two mixing products are
combined like this is usually termed Double-Sideband, DSB.
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It is conventional to call the higher frequency band of an image pair the
Upper-Sideband, USB, and the lower frequency band of an image pair the
Lower-Sideband, LSB.
Non-ideal mixers exhibit some unwanted behaviors:
1. Some of the input signal leaks directly to the output.
2. Some of the LO signal, and its harmonics, leak directly to the output.
3. Mixing products are created between the input signal and the harmonics
of the LO.
There are other unwanted products involving input signal harmonics, but
these tend to be less troublesome than those above, provided the mixer is
operated at a level within its linear range.
Signal Leakage
Direct signal leakage of input signal through to a mixer's output can occur,
because the noise sources cover a broad frequency range. Signal leakage is
not normally a problem unless the noise source has a large variation in ENR,
or the mixer's RF-to-IF leakage is high.
LO Leakage
The LO power is normally greater than the largest input signal that a mixer is
intended to operate with. The LO power leaking from the mixer's output is at
a high level compared to the signal levels involved in the noise figure
measurement. Hence, LO leakage needs to considered when measuring
noise figure of a frequency converting DUT.
If the LO frequency is low enough to be passed by the NFA's RF section’s
input filter (a 3.0 GHz Low Pass Filter), the LO leakage will force the NFA's
RF input attenuator to autorange onto a very insensitive range. This will
prevent successful measurement of the DUT noise figure. Desensitization by
LO leakage can be avoided by adding a filter between the DUT and the NFA
to remove the LO frequency component.
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LO Harmonics
Many mixers are operated by sinusoidal LO signals, LO harmonics can be
formed in the mixer at significantly high levels. It is common for the
specified LO input level for a diode mixer to be chosen to operate the diodes
between saturation and off conditions, hence making the mixer act as a
switch. LO harmonic derived products from industry standard
double-balanced mixers may be similar in level to what they would have
been with a square-wave LO signal. Instead of just being sensitive at one
pair of frequencies [ FLO ± FIF ] , the mixer input is sensitive at a series of
pairs:
Equation 4-1
[ F LO ± F IF ] + [ 2F LO ± F IF ] + [ 3F LO ± F IF ] + [ 4F LO ± F IF ] + [ 5F LO ± F IF ] + …
Filtering is needed to eliminate the noise input to the DUT at these higher
order frequencies. However, their frequencies may be great enough that the
mixer attenuates them, making them insignificant.
Other signals from the DUT
NFA RF input attenuator auto-ranging has already been covered in “LO
Leakage” on page 162. However, signals close to the tuned frequency can
de-sensitize the NFA measurements by forcing auto-ranging of the NFA's IF
gain control. The NFA has a similar, internal, limitation set by the LO
leakage of its own first mixer, and the requirement for the NFA to tune down
to 10 MHz. The NFA's analogue IF filter is designed for high rejection for
signals more than 10 MHz away from the tuned frequency. This is not
changed when narrow bandwidths are selected. An unwanted signal within
10 MHz of the tuned frequency could corrupt a noise figure measurement.
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Single Sideband Measurements
Most mixer applications involve single sideband (SSB) mixing - either LSB
or USB, hence it is ideal to make noise figure measurements on a mixer in
the circumstances in which it is used. Making an SSB measurement requires
suitable filters to remove the unwanted image, any LO leakage, and other
unwanted mixer products. This may require filters that are not available, or
expensive, and a DSB measurement may be chosen as a compromise. There
is no general guidance on what filtering is needed. Each case needs
individual consideration.
Items to be considered are:
1. Decide the frequency ranges that must be covered; Input, LO, and
Output.
2. Calculate the frequency range that the unwanted image will cover.
3. Calculate the frequency range that the LO harmonic modes will cover.
4. Choose a filter to go between the noise source and the DUT, that will
pass the wanted input band and stop the unwanted input bands.
5. Consider the LO frequency range (and harmonics), is a filter needed to
protect the NFA input being desensitized by LO leakage in the
0 - 3.5 GHz range?
6. Choose a filter, if necessary to go between the DUT and the NFA
If any of these ranges conflict, making the filter requirements impossible, the
measurement could be split into a group of smaller ranges, with different
filters for each.
If the DUT is a complicated mixer, it may already contain filters to operate
the mixer in single sideband mode over the frequency range of interest. A
mixer in its final application exhibits the same problems that make noise
figure measurement difficult, hence the application will need similar
filtering to that needed during noise figure measurement.
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Figure 4-8
Single Sideband Mixer Measurements
Amplitude
FLO
Flo-Flsb
mixing
Depending on Flo, a DUT
output filter may be needed
to reject LO leakage
Noise reaching mixer from
the DUT Input filter
Frequency
NFA Input
Band
LSB Input
USB Input
Figure 4-8 shows an SSB mixer measurement (Downconverter, LSB) where
a filter makes it single sideband. If the IF frequency is lowered - the NFA is
tuned to a lower frequency, the USB and LSB bands will move closer to the
LO frequency. This makes filtering more difficult, and if the IF is lowered
further, a point is reached where filtering is not possible and SSB
measurements cannot be made. The width of the filter limits where the LO
or IF frequencies sweep to make a measurement.
The NFA performs frequency calculations, controls the NFA frequency, and
the LO frequency, for a variety of mixer modes. However, you have to
determine the filter requirements, and provide those filters in the
measurement setup.
Downconverter means that the output frequency, (IF) is lower than the input,
(RF).
Upconverter means that the output frequency, (IF) is higher than the input
(RF).
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The NFA can handle SSB mixer measurements in modes defined by the
following combinational choices:
•
DUT: Upconverter or Downconverter
•
LO Mode: Fixed or Variable.
•
Sideband: LSB or USB.
Double Sideband Measurements
DSB techniques can make useful noise figure measurements. Consider the
following:
•
What if adequate filters for image-free SSB measurements are not
available?
•
What if frequency ranges have to be covered that make SSB filters
impractical or impossible?
DSB measurements do not eliminate the need for filtering, however, it can
greatly simplify the filtering needed. This benefit is achieved at the loss of
frequency resolution.
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Figure 4-9
Double Sideband Measurements
Amplitude
Fusb-Flo
mixing
FLO
Flo-Flsb
mixing
Frequency
NFA Input
Band
LSB Input
USB Input
Figure 4-9 shows a double sideband, downconversion, mixing. Noise from
two separated RF bands are mixed into the IF band, where the power
addition takes place.
DSB measurements are made with the noise from a pair of separate bands,
symmetrically arranged about the LO frequency. The selection of the IF
frequency value should be a low frequency. Hence this technique maintains
the two bands close together. The reason is to justify making the assumption
that the variations in noise source ENR, gain and noise figure are linear
between the two bands. This means that the averaging of results for the two
bands, due to the power summation, gives a result which can be assigned to
the centre frequency - the LO frequency.
Figure 4-9 shows that noise from two bands are combined during the
measurement, while during calibration, when the DUT was not connected,
only one band (at the IF frequency) was used.
If the assumptions about the parameters being flat over frequency between
the two sidebands are valid, this causes a doubling in power (3 dB increase)
in noise level during the measurement. This does not happen during
calibration. This can be corrected for, using the Loss Compensation
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facility, and entering Before DUT Value of -3 dB and selecting Fixed in the
Before DUT field. The DSB power addition occurs for both the Hot and
Cold noise from the noise source, and the noise created in the input of the
DUT. A temperature value can be assigned to this loss using the
Before Temperature. Using the Cold temperature of the noise source (often
assumed to be 290 Kelvin) corrects for this, and the NFA will give corrected
results comparable to those that would have been given by an SSB
measurement.
If you must use a high IF frequency, or if it has variations in performance
over frequency, then the assumption is invalid.
DSB measurements are not appropriate for making measurements where
DUT performance, or noise source ENR, have significant variation over the
frequency range [ FLO ± FIF ]
DSB measurements need care to determine their filtering needs.
LO Leakage (with specific DSB information)
LO leakage is a problem and is avoided by tuning the LO at frequencies
greater than 3.5 GHz. Below 3.0 GHz, the LO leakage drives the NFA to add
input attenuation to prevent overload, making the NFA insufficiently
sensitive to measure the noise component at the input. Above 3.0 GHz, the
NFA's input filter progressively attenuates the LO signal. For a DSB
downconverter measurement with the LO going below about 3.5 GHz, a
lowpass filter will be needed. The cutoff frequency must be chosen to pass
the IF frequency of the measurement. The amount of attenuation over the
LO frequency range has to be sufficient to reduce the LO leakage down to
the broadband (10.0 MHz - 3 GHz) noise level presented to the NFA input.
With most DSB Downconverter measurements, the IF is made low, with
respect to, the RF and LO frequencies, so filter needs are not complex.
NOTE
Low pass filters with cutoffs at low frequencies, may exhibit spurious
resonances and leakage at low microwave frequencies. It may be necessary
to use a pair of lowpass filters, one microwave, one RF, in order to assure a
stopband attenuation over a wide frequency range.
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LO Harmonics (with specific DSB information)
Many mixers have product pairs associated with harmonics of the LO.
Depending on the mixer, these could be at a sufficient level to distort the
measured noise figure results. To avoid this insert an input filter between the
noise source and the DUT. A Highpass filter may also be needed in this
location if signal leakage is a problem.
There is no general guidance on what filtering is needed. Each case needs
individual consideration:
1. Decide the frequency ranges that have to be covered; Input, LO, and
Output.
2. Calculate the frequency range that the LO harmonic modes will cover.
3. If LO harmonic related products are a problem, choose a filter to go
between the noise source and the DUT, that will pass the wanted input
band and stop the LO harmonic modes. If the frequency ranges are wide,
the measurement may have to be split into frequency ranges with
different filters for each.
4. Consider the LO frequency range (and harmonics), is a filter needed to
protect the NFA input being desensitized by LO leakage in the 0-3.5GHz
range?
5. Choose a filter, if necessary to go between the DUT and the NFA
The NFA can handle DSB mixer measurements in modes defined by the
following combinational choices:
•
DUT: Upconverter or Downconverter
•
LO Mode: Fixed or Variable.
•
Sideband: DSB.
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Fixed IF
In the fixed IF mode, the IF frequency at the NFA’s input is constant, and the
LO frequency is swept to perform the measurement.
Figure 4-10
Fixed IF Measurements
Sweep Point
Stop
Fusb-Flo
mixing
LSB Input
FLO
Flo-Flsb
mixing
USB Input
Frequency
Start
FIF
Figure 4-10 shows how the different frequencies in a DSB, downconverter,
fixed IF, measurement vary as the measurement sweep proceeds. This mode
measures the DUT's noise figure across a range of DUT input frequencies.
This is the main use of the DSB mode.
A similar diagram could be drawn, if needed, showing the LO harmonic
mixing modes at higher frequencies, with flatter slopes due to frequency
multiplication.
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Fixed LO
The fixed LO mode produces no sweep at the DUT input, as the two
sideband input pairs diverge their average remains fixed. This mode could
be useful for measuring a complex DUT where the effect of variation of
performance of the post-mixer stage over IF frequency is of interest.
Because the LO frequency is held constant it is the IF frequency at the NFA
input that is swept. Figure 4-11 illustrates this mode.
Figure 4-11
Fixed LO Measurements
Sweep Point
Fixed LO
Stop
Fusb-Flo
mixing
Flo-Flsb
mixing
LSB Input
USB Input
Start
FIF
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Frequency
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Making Frequency-Converting DUT Measurements
An example is provided where the NFA remains locked at one frequency and
the LO sweeps. A lower sideband measurement of a mixer is made. The
example can be modified to make measurements using a fixed LO where the
IF is swept. Also, from the example, upper and double side band
measurements can be made. The changes in the example’s procedure are
explained in each case.
Calibration of the measurement system is similar to a basic calibration, the
noise source is connected directly to the RF input of the NFA and a
calibration is made. The DUT is then placed between the noise source and
the NFA, and a corrected measurement is made.
NOTE
The RF input section on all NFA models has a built-in 3.0 GHz Low Pass
Filter. This filter needs to accounted for when planning your filter
requirements during calibration and measurement.
NOTE
On the N8974A and the N8975A models the microwave input section has no
filtering. This needs to accounted for when planning your filter requirements
for calibration and measurement. This is also important when making swept
IF measurements which cross over the 3.0 GHz switch.
Making Down-Converting DUT Measurements using a Fixed IF
and Variable LO (8970B Mode 1.3)
Lower Sideband Measurement (Fixed IF and Variable LO)
The example lower sideband measurement is made using a N8973A model.
The result is obtained by using a fixed IF of 1.0 GHz. Setting the RF
frequency of interest to be 3.7 GHz to 4.2 GHz, giving an LO sweep from
4.7 to 5.2 GHz. This also meets with the need to maintain the LO frequency
out of the NFA’s passband.
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The example uses a Signal Generator as a local oscillator. The system is used
to measure a mixer over a 3.7 to 4.2 GHz frequency range. The noise figure
for this mixer typically varies from 7 to 15 dB and the gain (conversion loss)
from -5 to -15 dB over this frequency band.
See Figure 4-12.
NOTE
In the example, a 4.4 GHz Low Pass Filter with an out of band rejection by
4.6 GHz is used to remove the upper sideband. (see Figure 4-12).
Figure 4-12
Fixed IF and Variable LO, LSB Spectrum
LPF
IF
3.7
1
2
3
RF 4.2
4
4.7 LO 5.2
Rejected
5.7 USB 6.2
5
6 (GHz)
Initial Setup Procedure Follow the overview procedure of the initial set
up.
Step 1. Power Up the NFA and the LO. You need to wait for the recommended
warm up time to get accurate measurement results
Step 2. Connect the GPIB cables and the 10 MHz reference, if required. See
“Connecting the System” on page 157 for more detail.
Step 3. Load the ENR values. See “Entering Excess Noise Ratio (ENR) Data” on
page 51 for more detail.
Step 4. Set up the LO and the NFA’s LO settings. See “Choosing and Setting Up the
Local Oscillator” on page 152 for more detail.
Step 5. Set the LO address
Step 6. Connect the system and add filtering where required. Figure 4-5 on page
158 shows the connections
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Selecting Measurement Mode
Figure 4-13
Measurement Mode Form
Step 1. Press the Meas Mode key. A Meas Mode Form is displayed (Figure 4-13).
Confirm that the Device Under Test field is set to Downconv (select the
Downconv menu key to highlight it).
The default Device Under Test setting is Amplifier.
NOTE
The System Downconverter field is no longer accessible to you in this
measurement mode.
Step 2. Press the Tab key to navigate to the LO Mode field and press the Variable
menu key for a variable LO setup.
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Selecting Mode Setup
Figure 4-14
Mode Setup Form
Step 1. Press the Mode Setup key. A Mode Setup Form is displayed (Figure
4-14).
This form allows you to enter values for the IF frequency, setup the LO
parameters and choose the sideband required.
Step 2. Press the Tab key to navigate to the IF Frequency field. Set the IF Frequency.
In the example, enter 1.0 GHz using the numeric keypad and terminate it
using the unit keys which are presented to you.
Step 3. Press the Tab key to navigate to the Sideband field. Set the Sideband.
In the example, enter LSB using the menu keys which are presented to you.
Step 4. Press the Tab key to navigate to the LO Control field. Set the LO Control.
In the example, enter on by pressing the On menu key which is presented to
you.
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Step 5. Press the Tab key to navigate to the External LO Power Level field. Set the
External LO Power Level.
In this example, enter 10 dBm using the numeric keypad and terminate it
using the unit keys which are presented to you.
Setting Frequency, Point, Bandwidth, Averaging
Step 1. Configure the measurement with the Frequency/Points and
Averaging/Bandwidth keys. For a description of these keys “Setting the
Measurement Frequencies” on page 65 and “Setting the Bandwidth and
Averaging” on page 71.
Set start and stop frequencies and number of points for the amplifier to be
tested. For the example microwave amplifier, the appropriate figures are:
NOTE
•
Start: 3700 MHz
•
Stop: 4200 MHz
•
Points: 15
•
Averaging: On
•
Averages: 5
•
Average Mode: Point
The N8972A Average Mode is set to point by default, as sweep mode is only
available on the other NFA models.
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Calibration of the Microwave Setup Calibration of the microwave
measurement system is similar to a basic RF calibration. If not done already,
connect the Noise Source output to the NFA input, see Figure 4-15.
Figure 4-15
Frequency Converting DUT Measurement Modes
Calibration Setup
Noise Source
LO
LO GPIB Control
Measurement Setup
Noise Source
DUT
Step 1. Press the Calibrate key twice
The first time you press the key you are prompted to press it again. This
two-stroke calibration is a safety feature to prevent you from accidentally
pressing Calibrate and erasing the calibration data.
When calibration is complete the measurement system is calibrated at the
mixer input. The white Uncorr text changes to Corr text in the lower right
hand side of the display.
NOTE
The calibration is only made at the fixed IF frequency.
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Calibration of the Microwave Setup
Step 1. Figure 4-16 shows typical results in table format after calibration.
Figure 4-16
Typical Calibration Results after a Restart is Pressed
NOTE
After calibration the instrument will not show 0 dB + jitter with no DUT
inserted. This is because the instrument is now using the microwave
frequency ENR, while the input is tuned to the IF. When DUT is added, the
NFA measures the noise figure of the DUT. If the configuration is arranged
to reject one sideband, the SSB result is displayed. If both sidebands are
converted by the mixer the DSB result is displayed.
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Making the Corrected Noise Figure and Gain Measurement A
measurement corrected for the second stage contribution may now be made.
Insert the DUT into the system as shown in Figure 4-15. The results are
displayed on the display using the same steps as those described in
“Displaying the Measurement Results” on page 81. A typical display of
noise figure and gain (conversion loss) is shown in Figure 4-17.
Figure 4-17
Typical Microwave Results
NOTE
Once you have successfully made your measurement you may want to save
the set up for future measurements. This can be done by saving the state. See
“Saving a File” on page 41 for more details.
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Upper Sideband Measurement (Fixed IF and Variable LO)
The upper single sideband measurement set up is similar to the LSB
measurement procedure described in “Lower Sideband Measurement (Fixed
IF and Variable LO)” on page 172. However, you need to provide filtering
to remove the LSB image. Follow the LSB procedure, and in the Mode
Setup Form select the USB in the sideband option.
NOTE
During measurement with the DUT inserted, it is important that the filter is
placed on the mixer input. Otherwise some added noise from the device
under test will likely be in the unwanted sideband and create a measurement
error. The filter must be in place for both calibration and measurement.
Double Sideband Measurement (Fixed IF and Variable LO)
The double sideband measurement set up is similar to the LSB measurement
described in “Lower Sideband Measurement (Fixed IF and Variable LO)” on
page 172. However, you need to provide filtering. Follow the LSB
procedure, and in the Mode Setup Form select the DSB in the sideband
option.
NOTE
During measurement with the DUT inserted, it is important that the filter is
placed on the mixer input. Otherwise some added noise from the device
under test will likely be in the unwanted sideband and create a measurement
error. The filter must be in place for both calibration and measurement.
NOTE
The calibration is only made at the IF frequency
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Making Down-converting DUT Measurements using a Variable
IF and Fixed LO (8970B Mode 1.4)
Both double and single sideband measurements may be made in this mode.
This measurement may be useful to choose the optimum IF for a mixer or
receiver, or to measure how a mixer’s or a receiver’s noise figure and gain
vary with IF.
Double Sideband Measurement (Variable IF and Fixed LO)
The double sideband measurement set up is similar to the LSB measurement
procedure described in “Lower Sideband Measurement (Fixed IF and
Variable LO)” on page 172. Follow the LSB procedure, and in the Mode
Setup Form select the DSB in the sideband option. On the Meas Mode
Form set the LO Mode to Fixed.
Lower Sideband Measurement (Variable IF and Fixed LO)
The lower sideband measurement set up is similar to the LSB measurement
procedure described in “Lower Sideband Measurement (Fixed IF and
Variable LO)” on page 172. However, you need to provide filtering. Follow
the LSB procedure, and in the Mode Setup Form select the LSB in the
sideband option. On the Meas Mode Form set the LO Mode to Fixed.
Upper Sideband Measurement (Variable IF and Fixed LO)
The upper sideband measurement set up is similar to the LSB measurement
procedure described in “Lower Sideband Measurement (Fixed IF and
Variable LO)” on page 172. However, you need to provide filtering. Follow
the LSB procedure, and in the Mode Setup Form select the USB in the
sideband option. On the Meas Mode Form set the LO Mode to Fixed.
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Making Up-converting DUT Measurements using a Fixed IF and
Variable LO (8970B Mode1.3 with SUM)
Making an up-converter measurement is similar to measuring down
converters. The terminology is the same as the downconverter mode, the
input to the NFA is called the IF and the noise source output is called the RF.
In the Meas Mode Form set the Device Under Test to Upconv.
Lower Sideband Measurement (Fixed IF and Variable LO)
The lower sideband measurement set up is similar to the LSB measurement
procedure described in “Lower Sideband Measurement (Fixed IF and
Variable LO)” on page 172. However, you need to provide filtering. Follow
the LSB procedure, and in the Mode Setup Form ensure the LSB in the
sideband option is selected. On the Meas Mode Form set the LO Mode to
Variable.
Upper Sideband Measurement (Fixed IF and Variable LO)
The upper sideband measurement set up is similar to the LSB measurement
procedure described in “Lower Sideband Measurement (Fixed IF and
Variable LO)” on page 172. However, you need to provide filtering. Follow
the LSB procedure, and in the Mode Setup Form select the USB in the
sideband option. On the Meas Mode Form set the LO Mode to Variable.
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Making Up-converting DUT Measurements using a Variable IF
and Fixed LO (8970B Mode1.4 with SUM)
Lower Sideband Measurement (Variable IF and Fixed LO)
The lower sideband measurement set up is similar to the LSB measurement
procedure described in “Lower Sideband Measurement (Fixed IF and
Variable LO)” on page 172. However, you need to provide filtering. Follow
the LSB procedure, and in the Mode Setup Form ensure the LSB in the
sideband option is selected. On the Meas Mode Form set the LO Mode to
Fixed.
Upper Sideband Measurement (Variable IF and Fixed LO)
The upper sideband measurement set up is similar to the LSB measurement
procedure described in “Lower Sideband Measurement (Fixed IF and
Variable LO)” on page 172. However, you need to provide filtering. Follow
the LSB procedure, and in the Mode Setup Form select the USB in the
sideband option. On the Meas Mode Form set the LO Mode to Fixed.
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Measurements with a System Downconverter
A system downconverter can be thought of as a frequency extender for the
NFA, to allow measurements to be made on DUTs at frequencies the NFA
does not cover with it’s frequency range.
Figure 4-18
System Downconverter Mode
LO
l LO GPIB
Calibration Setup
Noise Source
LO
Measurement Setup
LO GPIB
Noise Source
DUT
A system downconverter is part of the measuring system, and is present in
both the calibration setup and the measurement setup, see Figure 4-18.
During calibration the noise performance of both the NFA and the system
downconverter are measured. Because of this, when corrected measurements
are performed, the results apply to the DUT only. ENR data for the same
frequency range is used for both calibration and measurements
The NFA has the capability to control a single frequency conversion, so
system downconverter measurements under the NFA's control are limited to
non-frequency converting DUTs.
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The NFA can be used in much more complex systems, with multiple
frequency conversions between the DUT and measurement system.
However, the control of such systems is application-specific. You need to
perform frequency calculations to suit that particular system, account for the
effects of any DSB conversions, determine filter requirements, and calculate
the appropriate ENR values for calibration and measurement.
USB, LSB or DSB?
If the DUT is broadband, a system downconverter could operate in USB,
LSB, or DSB mode, and the same circumstances occur in both calibration
and measurements, hence DSB sideband power addition corrections are not
needed. Corrected measurements cancel any sideband summation effects.
If the DUT is narrowband and a DSB system downconverter is used, the
calibration setup will operate in true DSB mode. However, the measurement
setup mode will be influenced by the DUT’s selectivity.
The possibilities fit into two groups and a third situation which should be
avoided:
1. The DUT bandwidth is much greater than the LSB-USB separation, so a
normal DSB measurement results.
2. The DUT bandwidth is much less than the LSB-USB separation, and the
sweep width is less than the USB-LSB separation, so an SSB
measurement results. This needs a gain correction factor due to the DSB
calibration
NOTE
There is a third situation and this must be avoided. Where the DUT
selectivity can resolve the individual sidebands of the DSB measurement
and the sweep is wide enough to scan the DUT across them. Different parts
of the measurement plot are in different modes. USB, LSB and DSB could
occur in different places on the same plot, with gradual changes between
them, set by the shape of the DUT's frequency response. Variable gain
correction would be needed across the plot and the corrections needed would
change if adjustments to the DUT changed its shape.
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Measurement Modes with a DSB System Downconverter
The NFA supports only one DSB System Downconverter mode; where the
IF is fixed and the system downconverter LO is swept. The benefits of a
DSB measurement are, minimal filter requirements, and wide frequency
coverage. DSB measurements are appropriate for wideband DUTs. Their
disadvantages, covered in the “USB, LSB or DSB?” section, make them
inappropriate for narrowband DUTs. The usual aim is to choose as low a
frequency IF as possible, in order to minimize the separation between the
sidebands, thus get the optimum resolution possible. Figure 4-19 shows this.
Figure 4-19
DSB System Downconverter Measurements
Amplitude
Fusb-Flo
Flo-Flsb
LSB Input
USB Input
FLO
Broadband Noise
Frequency
NFA Input
Band
DSB system downconverter measurements have implicit linear averaging of
DUT characteristics and ENR values between the USB and LSB
frequencies. Results are made against the average frequency of the two
bands - the LO frequency.
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Figure 4-20
DSB System Downconverter Measurements
Sweep Point
Stop
Fusb-Flo
mixing
LSB Input
FLO
USB Input
Flo-Flsb
mixing
Frequency
Start
FIF
For microwave measurements, above 3.5 GHz, the NFA's input filter will
reject LO leakage from the downconverter, otherwise a filter is needed
between the system downconverter and the NFA. Also, considerations about
mixer LO harmonic modes apply.
Measurement Modes with an SSB System Downconverter
The NFA can perform frequency calculations and LO control for either USB
or LSB system downconverter conversions. It is the provision of filtering
that makes a mode USB or LSB.
The filtering requirements will be measurement-specific.
Figure 4-21 shows how filtering makes an LSB measurement, and Figure
4-22 shows a USB downconversion measurement.
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Figure 4-21
LSB System Downconverter Measurements
Amplitude
FLO
Flo-Flsb
mixing
Depending on Flo, a
downconverter output filter
may be needed to reject
LO leakage
Noise reaching mixer from
the DUT Input filter
Frequency
NFA Input
Band
Figure 4-22
LSB Input
USB Input
USB System Downconverter Measurements
Amplitude
Fusb-Flo
mixing
FLO
Noise reaching System
Downconverter is band
limited by filtering
Depending on Flo, a
downconverter output filter
may be needed to reject
LO leakage
Frequency
NFA Input
Band
188
LSB Input
USB Input
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Ideally choose a high IF frequency for the conversion to separate the USB
and LSB bands, thus reducing the filter requirements.
The filter needed to make an SSB measurement could be part of the DUT, or
a measurement-specific filter must be obtained and applied at the input to
the system downconverter.
The bandwidth of the SSB filter limits the maximum frequency range that a
measurement can be swept over. Therefore SSB measurements are not suited
to very wideband DUTs. However, variable LO (Fixed IF) SSB
measurements can be made over wider sweep widths than variable IF (Fixed
LO) measurements can be.
The NFA can perform frequency calculations and LO control for both USB
and LSB. It can perform both variable LO (NFA frequency fixed) and fixed
LO (NFA frequency swept). The fixed LO mode is useful where the
downconverter, has a fixed LO system. The sweep of the NFA's tuned
frequency causes the frequencies at which the system downconverter is
sensitive to sweep. Filtering is needed to select the wanted sideband. A
swept noise figure measurement is then possible even if the system LO
cannot be swept.
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FIXED IF, LSB:
Figure 4-23
LSB Measurements
Sweep Point
Filter Passband
LSB
FIF
Stop
FLO
USB
Flo-Flsb
mixing
Frequency
Start
Figure 4-23 shows a fixed-IF, LSB, system downconverter where the NFA
steps the LO through the sweep.
A filter is used to pass the LSB and reject the USB. Manufactured filters
cannot have infinite transition-band slopes, hence some margin is needed
between the maximum frequency of the LSB component (at the end of the
sweep) and the minimum frequency of the USB component (at the start of
the sweep). Choosing a high IF separates the USB and LSB frequencies
more, and allows a wider sweep, or a simpler filter. The filter could be a
lowpass or a bandpass, it must pass the range that the LSB frequency sweeps
over, while rejecting the range that the USB frequency sweeps over. Figure
4-23 shows that the sweep width cannot exceed twice the IF frequency.
You need to make an allowance for the filter's transition band.
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FIXED IF, USB:
Figure 4-24
USB Measurements
Sweep Point
Stop
Filter Passband
FIF
LSB
FLO
USB
Fusb-Flo
mixing
Frequency
Start
The fixed IF, USB mode is similar to the fixed IF, LSB mode. It allows the
measurement to extend up to 3.0 GHz higher than the maximum LO
frequency (1.5GHz with N8972A). The filter needs to be a bandpass or
highpass. A bandpass filter has an advantage in rejecting LO harmonic
mixing modes. This mode is shown in Figure 4-24, again, the sweep width is
limited to less than twice the IF frequency, less an allowance for the filter
transition band.
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FIXED LO, LSB
The main benefit of the fixed LO system downconverter modes is that a
programmable synthesized LO is not needed. The disadvantage is the
limited sweep width available, and the increased demands placed on the
sideband selection filters. These modes are suited to the measurement of
DUTs with narrow frequency bands of less than 4 MHz.
Figure 4-25
LSB Measurements
Sweep Point
Filter Passband
FIF
Stop
LSB
FLO
USB
Flo-Flsb
mixing
Start
Frequency
Figure 4-25 shows how the NFA sweeps its own input frequency backwards
from high to low frequency so that as the LSB tunes, the frequency increases
across the sweep. The filter required is either; a lowpass or a bandpass. The
maximum sweep width is now limited to the maximum IF frequency, less an
allowance for the filter transition band.
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FIXED LO, USB
Figure 4-26
USB Measurements
Sweep Point
Filter passband
FIF
LSB
FLO
USB
Stop
Fusb-Flo
mixing
Start
Frequency
Figure 4-26 shows as the NFA tunes in the normal direction for the fixed LO
USB mode. The filter can be a bandpass or highpass, and the sweep width is
again limited to the maximum IF frequency, less an allowance for the filter
transition band.
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Making System Downconverter Measurements
To make a System Downconverter measurement requires an external mixer
and local oscillator. In this mode the frequency conversion is in the
measurement system, not in device under test.
An example is provided where the NFA remains locked at one frequency and
the LO sweeps with the noise source input frequency. A double sideband
measurement of an amplifier is made. The example can be modified to make
measurements using a fixed LO where the IF is swept. Also, from the
example, upper and lower side band measurements can be made. The
changes in the example’s procedure are explained in each method.
NOTE
The RF input section on all NFA models has a built-in 3.0 GHz Low Pass
Filter. This filter needs to accounted for when planning your filter
requirements during calibration and measurement.
NOTE
On the N8974A and the N8975A models the microwave input section has no
filtering. This needs to accounted for when planning you filter requirements
for calibration and measurement. This is also important when making
measurements which cross over the 3.0 GHz switch.
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Using a Fixed IF and Variable LO (8970B Mode1.1)
In this mode the LO sweeps with the input frequency and the NFA is set at a
fixed IF frequency. The IF frequency and the measurement input frequency
range values are entered into the analyzer. The NFA calculates the set of
frequencies that the LO will be swept over.
Double Sideband Measurement (Fixed IF and Variable LO)
The example double sideband measurement is made using a N8973A model.
The result is obtained, by using a fixed IF of 1.0 GHz. Setting the frequency
of interest to be 3.6 GHz to 4.0 GHz, giving an LO sweep from 3.6 GHz to
4.0 GHz. This also meets with the need to maintain the LO frequency out of
the NFA’s passband.
NOTE
Typically select an low IF, as there may be differences in ENR values. Also,
differences in gain performance at the two sidebands.
The example uses the a Signal Generator as a local oscillator, and a mixer to
downconvert to the frequency range of the NFA. The system is used to
measure a 2000 to 4300 MHz amplifier over a 3.6 to 4.0 GHz frequency
range. The noise figure for this amplifier typically varies from 6 to 10 dB
and the gain from 15 to 5 dB over this reduced frequency band. Figure 4-27
shows the frequencies involved.
NOTE
Filtering is not needed in the DSB mode. Ensure the LO frequencies are out
of the passband range of the NFA, Hence, LO sweep is always greater than
3.5 GHz over its swept range.
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Figure 4-27
Variable LO, Fixed IF, DSB Spectrum
LO
RF
IF
1
3.6
2
3
4.0
4
6 (GHz)
5
Initial Setup Procedure
Follow the overview procedure of the initial set up.
Step 1. Power Up the NFA and the LO. You need to wait for the recommended
warm up time to get accurate measurement results
Step 2. Connect the GPIB cables and the 10 MHz reference, if required. See
“Connecting the System” on page 157 for more detail.
Step 3. Load the ENR values. See “Entering Excess Noise Ratio (ENR) Data” on
page 51 for more detail.
Step 4. Set up the LO and the NFA’s LO settings. See “Choosing and Setting Up the
Local Oscillator” on page 152 for more detail.
Step 5. Set the LO address
Step 6. Connect the system and add filtering where required. Figure 4-4 on page
158 shows the connections
NOTE
The LO GPIB menu key accesses the System LO GPIB Form. This
feature is currently not supported, as currently only the NFA can act as GPIB
controller. Hence, if the LO Control is set to On in the
Mode Set Up Form, the NFA controls the LO.
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Selecting Measurement Mode
Figure 4-28
Measurement Mode Form
Step 1. Press the Meas Mode key. A Meas Mode Form is displayed (Figure 4-28).
Confirm that the Device Under Test field is set to Amplifier.
Use the Tab key to move round the form and in the Device Under Test field
select the Amplifier menu key to highlight it. The default
Device Under Test setting is Amplifier.
Step 2. Press the Tab key to navigate to the System Downconverter field and press
the On menu key to turn on system down conversion.
Step 3. Press the Tab key to navigate to the LO Mode field and press the Variable
menu key for a variable LO setup.
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Selecting Mode Setup
Figure 4-29
Mode Setup Form
Step 1. Press the Mode Setup key. A Mode Setup Form is displayed (Figure
4-29).
This form allows you to enter values for the IF frequency, setup the LO
parameters and choose the sideband required.
Step 2. Press the Tab key to navigate to the IF Frequency field. Set the IF
Frequency.
In the example, enter 1.0 GHz using the numeric keypad and terminate it
using the unit keys which are presented to you.
Step 3. Press the Tab key to navigate to the Sideband field. Set the Sideband.
In the example, enter DSB using the menu keys which are presented to you.
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Step 4. Press the Tab key to navigate to the LO Control field. Set the LO Control.
In the example, enter on by pressing the On menu key which is presented to
you.
Step 5. Press the Tab key to navigate to the External LO Power Level field. Set the
External LO Power Level.
In this example, enter 10 dBm using the numeric keypad and terminate it
using the unit keys which are presented to you.
Setting Frequency, Point, Bandwidth, Averaging
Step 1. Configure the measurement with the Frequency/Points and
Averaging/Bandwidth keys. For a greater description of these keys, see
“Setting the Measurement Frequencies” on page 65 and “Setting the
Bandwidth and Averaging” on page 71.
Set start and stop frequencies and number of points for the amplifier to be
tested. For the example amplifier, the appropriate figures are:
NOTE
•
Start: 3600 MHz
•
Stop: 4000 MHz
•
Points: 15
•
Averaging: On
•
Averages: 5
•
Average Mode: Point
•
Bandwidth: 4 MHz
The N8972A Average Mode is set to point by default, as sweep mode is only
available on the other NFA models.
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Calibration of the DSB Setup Calibration of the DSB measurement setup
requires, if not done already, you to attach the mixer LO port to the output of
the LO, connect the Noise Source output to the mixer RF input, and connect
the mixer IF output to the NFA input, see Figure 4-30.
Figure 4-30
System Downconverter Mode
LO
LO GPIB
Calibration Setup
Noise Source
LO
Measurement Setup
LO GPIB
Noise Source
DUT
Step 1. Press the Calibrate key twice
The first time you press the key you are prompted to press it again. This
two-stroke calibration is a safety feature to prevent you from accidentally
pressing Calibrate and erasing the calibration data.
When the calibration is complete the measurement set up is calibrated at the
mixer input. The white Uncorr text changes to yellow Corr text in the
lower right hand side of the display. The second stage calibration now
includes the mixer, the LO, the cables, adapters, and the NFA.
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Figure 4-31 shows typical results in table format after calibration. It is good
practice to measure the gain and noise figure of the direct connection before
the DUT is inserted.
Figure 4-31
Typical Calibration Results after a Restart is Pressed
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Making the Corrected Noise Figure and Gain Measurement A
measurement corrected for the second stage contribution may now be made.
Insert the DUT into the system as shown in Figure 4-30. The results are
displayed on the display using the same steps as those described in
“Displaying the Measurement Results” on page 81. A typical display of
noise figure and gain is shown in Figure 4-32.
Figure 4-32
Typical DUT Results
NOTE
Once you have successfully made your measurement you may want to save
the set up for future measurements. This can be done by saving the state. See
“Saving a File” on page 41 for more details.
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Lower Single Sideband Measurement (Fixed IF and Variable LO)
The lower single sideband measurement set up is similar to the DSB
measurement. However, you need to provide filtering to remove the USB
image. Follow the DSB procedure, however in the Mode Setup Form
select the LSB in the sideband option.
NOTE
During measurement with the DUT inserted, it is important that the filter be
on the mixer input rather than the noise source output. Otherwise some
added noise from the device under test will likely be in the unwanted
sideband and create a measurement error. The filter must be in place for both
calibration and measurement.
Upper Single Sideband Measurement (Fixed IF and Variable LO)
The upper single sideband measurement set up is similar to the DSB
measurement. However, you need to provide filtering to remove the LSB
image. Follow the DSB procedure, however in the Mode Setup Form
select the USB in the sideband option.
NOTE
During measurement with the DUT inserted, it is important that the filter be
on the mixer input rather than the noise source output. Otherwise some
added noise from the device under test will likely be in the unwanted
sideband and create a measurement error. The filter must be in place for both
calibration and measurement.
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Using a Variable IF and Fixed LO (8970B Mode1.2)
In this mode the NFA sweeps with the input frequency and the LO is set to a
fixed frequency. The LO frequency and the measurement input frequency
range values are entered into the analyzer. The NFA calculates the set of
frequencies that the IF is swept over.
NOTE
Even if the LO is not controlled by the NFA the LO’s frequency value must
be entered in the Mode Setup Form.
A measurement with a variable IF, always requires a single-sideband
measurement. Hence the need to filter the unwanted sideband in the
measurement setup.
Calibration in this mode is the same as for the variable LO single-sideband
modes, and you need to ensure that the filter is in place for both the
calibration and the measurement.
Connecting the System
To connect the calibration and measurement set up for this mode see Figure
4-33. If the NFA is the controller as in the previous section, and the LO is
one that can respond over GPIB, this automatically sets the LO frequency.
If the LO cannot respond over GPIB or using the custom commands, you
can set the frequency and amplitude manually to a fixed value. However, the
frequency value must be entered in the Mode Setup Form in the NFA.
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Figure 4-33
System Downconverter Mode
LO
LO GPIB
Calibration Setup
Noise Source
LO
Measurement Setup
LO GPIB
Noise Source
DUT
Lower Sideband Measurement (Variable IF and Fixed LO)
The lower single sideband measurement set up is similar to the DSB
measurement example, see “Double Sideband Measurement (Fixed IF and
Variable LO)” on page 195. However, you need to provide filtering to
remove the USB image. Follow the DSB procedure, and the Mode Setup
Form select the LSB in the sideband option. On the Meas Mode Form
select the LO Mode to Fixed.
NOTE
During measurement with the DUT inserted, it is important that the filter be
on the mixer input rather than the noise source output. Otherwise some
added noise from the device under test will likely be in the unwanted
sideband and create a measurement error. The filter must be in place for both
calibration and measurement.
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Upper Sideband Measurement (Variable IF and Fixed LO)
The upper single sideband measurement set up is similar to the DSB
measurement example, see “Double Sideband Measurement (Fixed IF and
Variable LO)” on page 195. However, you need to provide filtering to
remove the LSB image. Follow the DSB procedure, and the Mode Setup
Form select the USB in the sideband option. On the Meas Mode Form
select the LO Mode to Fixed.
NOTE
During measurement with the DUT inserted, it is important that the filter be
on the mixer input rather than the noise source output. Otherwise some
added noise from the device under test will likely be in the unwanted
sideband and create a measurement error. The filter must be in place for both
calibration and measurement.
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Frequency Restrictions
Frequency Restrictions
To assist you troubleshoot problems encountered when setting up these
measurement modes, there are restrictions that apply to the mode of
operation.
Glossary of Restricted Terms
Table 4-3 is a description of the terms used in the restrictions
Table 4-3
Restricted Terms
Term
Description
fFIF
Fixed IF
fFLO
Fixed LO frequency
fLO
External LO frequency
fSIF
System input frequency
fSTART
Start frequency
fSTOP
Stop frequency
IF
The output from DUT frequency or
the tuned frequency of the NFA
RF
The input to DUT frequencies
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General Restrictions
In the measurement modes the following general restrictions apply:
NOTE
•
The Fixed IF frequency, fFIF, limits are defined by the NFA's minimum
and maximum system input frequencies, fSIF(MIN) and fSIF(MAX)
respectively. For example, the N8973A has fSIF(MIN) = 10 MHz and
fSIF(MAX) = 3 GHz.
•
Fixed LO frequency, fFLO, limits are defined by the external LO's
minimum and maximum frequencies, fLO(MIN) and fLO(MAX)
respectively, as entered in the System?External LO menu.
Whether the input frequencies are RF or IF frequencies, the Frequency menu
is used to enter these frequency values.
•
For modes with a fixed IF, the frequency span, fSPAN, is limited to fSTOP
- fSTART.
•
For modes with a variable IF, the frequency span, fSPAN, is limited to
fSIF(MAX) - fSIF(MIN).
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Frequency Restrictions
Frequency-Downconverting DUT
In this mode, the DUT contains a frequency down-converting device. For
example, a mixer or receiver.
Fixed IF Variable LO
These are the restrictions applicable to this mode.
LSB Restrictions In the LSB, Fixed IF Variable LO mode the following
restrictions apply:
•
fRF(START) > fFIF
If this restriction is broken, Mode setup error;Start freq must
be greater than fixed IF freq is generated.
To resolve this error condition, decrease fFIF or increase fRF(START).
USB Restrictions In the USB, Fixed IF Variable LO mode the following
restrictions apply:
•
fLO(START) > fFIF
If this restriction is broken, Mode setup error;Start LO freq
must be greater than fixed IF freq is generated.
To resolve this error condition, decrease fFIF or increase fRF(START).
DSB Restrictions In the DSB, Fixed IF Variable LO mode the following
restrictions apply:
•
fRF(START) > fFIF
If this restriction is broken, Mode setup error;Start freq must
be greater than fixed IF freq is generated.
To resolve this error condition, decrease fFIF or increase fRF(START).
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Variable IF Fixed LO
These are the restrictions applicable to this mode.
LSB Restrictions In the LSB, Variable IF Fixed LO mode the following
restrictions apply:
•
fIF(STOP) < fRF(STOP)
If this restriction is broken, Mode setup error;Stop freq must
be less than stop RF freq is generated.
To resolve this error condition, increase fFLO or decrease fIF(STOP).
USB Restrictions In the USB, Variable IF Fixed LO mode the following
restrictions apply:
•
fIF(STOP) < fFLO
If this restriction is broken, Mode setup error;Stop freq must
be less than fixed LO freq is generated.
To resolve this error condition, increase fFLO or decrease fIF(STOP).
DSB Restrictions In the DSB, Variable IF Fixed LO mode the following
restrictions apply:
•
fIF(STOP) < fRF(STOP)
If this restriction is broken, Mode setup error;Stop freq must
be less than stop RF freq is generated.
To resolve this error condition, increase fFLO or decrease fIF(STOP).
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Frequency Restrictions
Frequency Up-converting DUT
In this mode, the DUT contains a frequency up-converting device. For
example, a transmitter.
Fixed IF Variable LO
These are the restrictions applicable to this mode.
LSB Restrictions In the LSB, Fixed IF Variable LO mode the following
restrictions apply:
•
fRF(STOP) < fFIF
If this restriction is broken, Mode setup error;Stop freq must
be less than fixed IF freq is generated.
To resolve this error condition, increase fFIF or decrease fRF(STOP).
USB Restrictions In the USB, Fixed IF Variable LO mode the following
restrictions apply:
•
fRF(STOP) < fLO(STOP)
If this restriction is broken, Mode setup error;Stop freq must
be less than stop LO freq is generated.
To resolve this error condition, increase fFIF or decrease fRF(STOP).
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Variable IF Fixed LO
These are the restrictions applicable to this mode.
LSB Restrictions In the LSB, Variable IF Fixed LO mode the following
restrictions apply:
•
fIF(STOP) < fFLO
If this restriction is broken, Mode setup error;Stop freq must
be less than fixed LO freq is generated.
To resolve this error condition, increase fFLO or decrease fIF(STOP).
•
fIF(START) > fRF(START)
If this restriction is broken, Mode setup error;Start freq must
be greater than start RF freq is generated.
To resolve this error condition, decrease fFLO or increase fIF(START).
USB Restrictions In the USB, Variable IF Fixed LO mode the following
restrictions apply:
•
fIF(START) > fFLO
If this restriction is broken, Mode setup error;Start freq must
be greater than fixed LO freq is generated.
To resolve this error condition, decrease fFLO or increase fIF(START).
•
fRF(STOP) < fFLO
If this restriction is broken, Mode setup error;Stop RF freq
must be less than fixed LO freq is generated.
To resolve this error condition, increase fFLO or decrease fIF(STOP).
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System Downconverter
The DUT is a non-frequency converting device, for example an amplifier or
filter measurement, and its frequency is outside the NFA’s measurement
range (frequencies less than 10 MHz or greater than 3.0 GHz). Frequency
down-conversion is required within the measurement system, in other
words, using a mixer, external to the DUT, to convert the signal of interest to
the frequency range of the NFA.
Fixed IF Variable LO
These are the restrictions that apply to this mode.
DSB Restrictions
In the DSB, Fixed IF Variable LO mode the following restrictions apply:
•
fRF(START) > fFIF
If this restriction is broken, Mode setup error;Start freq must
be greater than fixed IF freq is generated.
To resolve this error condition, decrease fFIF or increase fRF(START).
LSB Restrictions
In the LSB, Fixed IF Variable LO mode the following restrictions apply to
the set up:
•
fRF(START) > fFIF
If this restriction is broken, Mode setup error;Start freq must
be greater than fixed IF freq is generated.
To resolve this error condition, decrease fFIF or increase fRF(START).
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USB Restrictions
In the USB, Fixed IF Variable LO mode the following restrictions apply to
the set up:
•
fRF(START) > fFIF
If this restriction is broken, Mode setup error; Start freq must
be greater than fixed IF freq is generated.
To resolve this error condition, decrease fFIF or increase fRF(START).
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Frequency Restrictions
Variable IF Fixed LO
These are the restrictions applicable to this mode.
LSB Restrictions
In the LSB, Variable IF Fixed LO mode the following restrictions apply:
•
fRF(STOP) < fFLO
If this restriction is broken, Mode setup error;Stop freq must
be less than fixed LO freq is generated.
To resolve this error condition, increase fFLO or decrease fRF(STOP).
•
fRF(START) > fIF(START)
If this restriction is broken, Mode setup error;Start freq must
be greater than start IF freq is generated.
To resolve this error condition, decrease fFLO or increase fRF(START)
•
fFLO - fRF(STOP) > fSIF(MIN)
If this restriction is broken, Mode setup error;LO - Stop freq
must be >= min system input freq is generated.
To resolve this error condition, increase fFLO or decrease fRF(STOP)
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Frequency Restrictions
USB Restrictions
In the LSB, Variable IF Fixed LO mode the following restrictions apply:
•
fRF(START) > fFLO
If this restriction is broken, Mode setup error; Start freq must
be greater than fixed LO freq is generated.
To resolve this error condition, decrease fFLO or increase fRF(START).
•
fIF(STOP) < fFLO
If this restriction is broken, Mode setup error; Stop IF freq
must be less than fixed LO freq is generated.
To resolve this error condition, increase fFLO or decrease fRF(STOP).
•
fRF(START) - fFLO > fSIF(MIN)
If this restriction is broken, Mode setup error; Start - LO freq
must be >= min system input freq is generated.
To resolve this error condition, decrease fFLO or increase fRF(START).
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Performing System Operations
This chapter describes how to perform the system-level tasks, such as
configuring the Noise Figure Analyzer’s GPIB address, defining the preset
conditions and so forth.
217
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What You will Find in this Chapter
What You will Find in this Chapter
This chapter covers:
•
Setting the GPIB Addresses
•
Configuring the Serial Port
•
Configuring the Characteristics of an External LO
•
Configuring the Internal Alignment
•
Displaying Error, System and Hardware Information
•
Presetting the Noise Figure Analyzer
•
Defining the Power-On/Preset Conditions
•
Restoring System Defaults
•
Setting the Time and Date
•
Configuring a Printer with the NFA
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Setting the GPIB Addresses
Setting the GPIB Addresses
Purpose of the
GPIB and LO
GPIB
The NFA has two GPIB connectors on its rear panel. One connector is used
for communicating with a computer using the remote command set and the
other connector, the LO GPIB, is used by the NFA to control an external
local oscillator. The NFA acts as the controller over the LO GPIB.
To Set the GPIB Addresses
Step 1. Press the System key
Step 2. Press the GPIB menu key.
The System GPIB Form now appears in the display. See Figure 5-1.
Figure 5-1
System GPIB Form
Step 3. Using the Tab key to navigate through the form configure the GPIB
parameters as required.
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Setting the GPIB Addresses
The System GPIB parameters are described in Table 5-1.
Table 5-1
System GPIB parameters
Parameter
Description
Noise Figure Analyzer
Address
The instrument’s GPIB address.
Valid addresses are from 0 to 30.
Default is 8.
External LO Address
The GPIB address of the External LO attached to
the LO GPIB.
Valid addresses are from 0 to 30.
Default is 19.
LO GPIB Address
The address through which devices, attached to the
LO GPIB, communicate with the instrument.
Valid addresses are from 0 to 30.
Default is 8
NOTE
Ensure the Remote Port menu key is set Remote Port(GPIB).
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Configuring the Serial Port
Configuring the Serial Port
The NFA has a serial port on the rear panel to allow the it to communicate
using the remote command set.
To configure the serial port:
Step 1. Press the System key
Step 2. Press the Serial menu key.
The System Serial Form now appears. See Figure 5-2
Figure 5-2
System Serial Form
Step 3. Use the Tab keys to navigate through the form and the menu keys to
configure the serial parameters as required.
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Configuring the Serial Port
The System serial port parameters are described in Table 5-2.
Table 5-2
Serial port parameters
Parameter
Description
Data Terminal Ready
Sets the DTR line control.
Request To Send
Baud
•
OFF de-asserts DTR, hence disabling the serial
port
•
ON asserts DTR, hence enabling the serial port
•
IBF tells the driver to use DTR for data pacing
Sets the RTS line control.
•
OFF de-asserts RTS, hence disabling the serial
port
•
ON asserts RTS, hence enabling the serial port
•
IBF tells the driver to use RTS for data pacing
Sets the Baud rate of the NFA’s serial port.
Note: The value you set here must match the Baud
rate of the connected device.
Receive Pacing
Transmit Pacing
NOTE
Sets the receive pacing handshake characters.
•
NONE
•
XON/XOFF
Sets the transmit pacing handshake characters.
•
NONE
•
XON/XOFF
Ensure the Remote Port menu key is set Remote Port(Serial). The NFA
needs a power cycle to take effect if you changed it from
Remote Port(GPIB),
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Configuring the Characteristics of an External LO
Configuring the Characteristics of an External LO
The NFA can control an external LO using its LO GPIB port. The External
LO menu allows you to configure the following characteristics of the
external LO:
NOTE
•
Type of command set used: the default is SCPI, however, the NFA also
allows you to create and use custom command sequences for LOs that do
not use SCPI commands.
•
The minimum and maximum input frequencies of the LO: See
“Minimum and Maximum Frequencies” on page 226.
•
The settling time of the LO: See “Settling Time” on page 226.
•
The frequency multiplier of the LO: See “Multiplier” on page 227.
•
Auxiliary command, if any used, for example, Continuous Wave (CW) or
Modulation type.
The custom command sequence is stored as part of the “persistent”
instrument state.
Custom Command Set
The custom command set allow you to customize a command set to define
the operation of a non-SCPI compliant LO.
The custom command set supports an LO that could use a maximum of
seventy-nine characters in the prefix and suffix. These characters include the
prefix characters and the suffix characters.
The purpose of the frequency prefix and suffix is to correctly format the
commands from the NFA to the LO. The format is different for different
LOs. The frequency information is determined by the frequency parameters
entered into the NFA during the measurement setup and by the measurement
mode in which the NFA is operating.
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Configuring the Characteristics of an External LO
The purpose of the Power prefix and suffix is to set the output signal power
level of the LO. The allowable range is from -100 to +100 dBm. The actual
output signal power level is limited by the output signal power level
capability of the LO.
The purpose of the auxiliary command is to set other features in the LO, for
example, enable RF output (OUTP:STAT ON).
To access the menu to configure the command characteristics of an external
LO follow the procedure:
Step 1. Press the System key.
Step 2. Select the External LO menu key.
Step 3. Select the LO Commands menu key.
You are presented with an External LO Commands Form.
Figure 5-3
External LO Commands Form
NOTE
The default suffix commands have an intentional space inserted.
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Step 4. Press the Tab key to move the highlight to the required position in the form.
You can choose to enter the Prefix and Suffix of the power commands and
frequency commands. Also you can enter an auxiliary command. This
procedure explains this process using the auxiliary commands.
Figure 5-4
External LO Auxiliary Menu Keys
•
Selecting the Clear Command menu key, clears the current command.
See Figure 5-4 showing the Auxiliary menu keys.
•
Selecting the Change Command menu key, you are presented with an
Alpha Editor. This and the numeric keys allows you to enter a command
string, see Figure 5-5. Press the Prev key to enter the command. The
command string can have up to a maximum of seventy-nine characters.
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Configuring the Characteristics of an External LO
Figure 5-5
External LO Auxiliary Command Changes
Settling Time
The purpose of the settling time is to ensure that the NFA waits a sufficient
amount of time after issuing a frequency or power command to allow the
LO’s output to stabilize.
Pressing the Settling Time menu key allows you to set the settling time of
NFA. Valid settling times are between 0 ms and 100 s. The default value is
100 ms.
Minimum and Maximum Frequencies
The minimum and maximum frequencies represent the frequency capability
of the LO. They are only used by the NFA to determine if the frequencies
needed by the measurement are acceptable.
Pressing the Min Freq menu key allows you to set the minimum frequency
the NFA expects the External LO to have. The default value is 10 MHz.
Pressing the Max Freq menu key allows you to set the maximum frequency
the NFA expects the External LO to have. The default value is 40.0 GHz.
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Configuring the Characteristics of an External LO
Multiplier
The external LO frequency multiplier value sets the frequency multiplying
factor of the external LO.
Pressing the Multiplier menu key allows you to set the multiplier frequency
of the External LO. The default value is 1.
NOTE
When using the multiplier feature and setting the minimum and maximum
frequencies capabilities of the external LO, note that these limits refer to the
multiplied frequency input to the DUT. For example, with a multiplier of 4,
and an external LO which can operate from 10 MHz to 20 GHz, the limits
should be set to 40 MHz and 80 GHz.
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Configuring the Internal Alignment
Configuring the Internal Alignment
Data from the internal alignment routine is necessary for accurate NFA
operation. When enabled, the internal alignment routine runs continuously to
ensure that the NFA is using current alignment data which improves the
NFA’s accuracy.
Alignment is the process of routing a known internally generated signal
through a selected signal path and measuring the signal. This measured
value is then compared with the expected value in order to derive the
correction needed to convert the measured value to the expected value.
No external connections are needed.
Turning Alignment Off and On
Step 1. Press the System key.
Step 2. Press the Alignment menu key to access the Alignment menu.
Step 3. Press the Alignment menu key selecting Alignment(On) or Alignment(Off)
as required.
The default setting is Alignment(On).
Changing Alignment Mode
Step 1. Press the System key.
Step 2. Press the Alignment menu key to access the Alignment menu.
Step 3. Press the Alignmnt Mode menu key selecting Alignmnt Mode(Point) or
Alignmnt Mode(Sweep) as required.
The default mode setting is Alignmnt(Sweep).
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Configuring the Internal Alignment
Alignment of the YIG Tuned Filter (YTF)
NOTE
The YTF alignment feature only applies to the N8974A and the N8975A
models.
Step 1. Press the System key.
Step 2. Press the Alignment menu key to access the Alignment menu.
Step 3. Press the Align YTF menu key to set the YTF alignment.
You are prompted to press this key again. This feature ensures you do not
accidently erase the current YTF alignment data.
Step 4. Wait until the Alignment routine has completed.
Step 5. Press the Save YTF Alignment menu key to store the Alignment data.
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Displaying Error, System and Hardware Information
Displaying Error, System and Hardware Information
Displaying the Error History
The 10 most recent errors are stored in an error queue which you can display
as a full size table. The most recent messages appear at the top of the table.
To display the error queue:
Step 1. Press the System key and the More 1 of 3 menu key.
Step 2. Press Show Errors menu key to view the error queue.
To clear the error screen, press Clear Error Queue.
Displaying System Information
You can display the instrument product number, serial number, memory,
loaded firmware details and fitted options.
Step 1. Press the System key and the More 1 of 3 menu key.
Step 2. Press Show System menu key to view system information.
Displaying Hardware Information
Step 1. Press the System key and the More 1 of 3 menu key.
Step 2. Press Show Hdwr menu key to view hardware information.
The name and version numbers of the hardware modules in the instrument
are now displayed.
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Presetting the Noise Figure Analyzer
Presetting the Noise Figure Analyzer
Pressing the Preset key places the NFA in a known state and provides a
convenient starting point for making most measurements. You can specify
the preset state with the Preset menu key located under the System key.
To preset the analyzer using its factory defaults:
Step 1. Turn the NFA on by pressing the On key and wait for the power on process
to complete.
Step 2. Press System key, More 1 of 3, Power On/Preset, Preset (Factory) menu
keys.
Step 3. Press the green Preset key.
The instrument preset function performs a processor test but does not affect
alignment data. Pressing Preset clears both the input and output buffers. The
status byte is set to 0.
NOTE
Turning on the analyzer performs an instrument preset. Turning on the
analyzer also fetches alignment data; clears both the input and output
buffers; and sets the status byte to 0. The last state of the analyzer before it
was turned off is recalled when Power On(Last) is selected (under the
System key).
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Defining the Power-On/Preset Conditions
Defining the Power-On/Preset Conditions
The power up and preset conditions can be different if required. You can set
the NFA to return it to a user-defined state after a power on or preset.
Setting the Power On Conditions
Step 1. Press the System key and the More 1 of 3 menu key.
Step 2. Press the Power On/Preset menu key.
Step 3. Set Power On to Power On(Last) or Power On(Preset) as required.
‘Last’ means that the instrument, upon power on returns to the state it was in
when it was powered off.
‘Preset’ means the instrument returns to its defined preset state.
Setting the Preset Conditions
You can set the NFA to return to its factory default state or a user defined
state upon preset. The configured user defined state is provided by pressing
the Save User Preset menu key to save the current NFA state
To set the preset conditions to factory default
Step 1. Press the System key and the More 1 of 3 menu key.
Step 2. Press the Power On/Preset menu key.
Step 3. Enable the Preset(Factory) menu key.
To set the preset conditions to user defined
Step 1. Configure the NFA to the desired state.
Step 2. Press the System key and the More 1 of 3 menu key.
Step 3. Press the Power On/Preset menu key.
Step 4. Enable the Preset(User) menu key.
Step 5. Press the Save User Preset menu key to save the current NFA state.
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Restoring System Defaults
Restoring System Defaults
This will reset the NFA to the original factory default settings. It will also
clear the non-volatile memory of ENR tables, limit lines, address setting,
and so forth.
To restore the system defaults:
Step 1. Press the System key
Step 2. Press the More 1 of 3 menu key.
Step 3. Press the Restore Sys Defaults menu key.
Press the Restore Sys Defaults menu key again.
NOTE
You are prompted to press this key again. This feature ensures you do not
accidently restore the original factory default settings.
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Setting the Time and Date
Setting the Time and Date
The NFA allows you to set and display the time and date. The date can be set
in US or European format as required.
To turn the time and date on and off
Step 1. Press the System key.
Step 2. Press the More 1 of 3 menu key.
Step 3. Press the Time/Date menu key.
Step 4. Press the Time/Date menu key to select Time/Date(On) or Time/Date(Off)
as required.
The default is Time/Date(On).
To set the time and date
Step 1. Press the System key.
Step 2. Press the More 1 of 3 menu key.
Step 3. Press the Time/Date menu key.
Step 4. Set the Date Mode to either US format MDY (Month/Day/Year) or European
format DMY (Day/Month/Year).
US format is the default setting.
Step 5. Enter the time in hhmmss (hours, minutes, seconds) format.
Step 6. Enter the date in yyyymmdd (year, month, day) format.
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Configuring a Printer with the NFA
Configuring a Printer with the NFA
Printer
requirements
•
IEEE 1284 compliant printer cable.
•
Supported printer equipped with a parallel interface. A supported printer
is one that accepts Printer Control Language Level 3 or 5.
— PCL3 printers include most HP DeskJet printers.
— PCL5 printers include most HP LaserJet printers and the HP 1600C
DeskJet printer.
Printer
connection
To connect your printer to the NFA, connect the printer to the parallel I/O
interface connector of the NFA using an IEEE 1284 compliant parallel
printer cable.
If appropriate, configure your printer (see your printer documentation for
more details on configuring your printer).
To Configure a Printer with the NFA
Step 1. Power on the NFA and the printer.
Step 2. Press the Print Setup key and then press the Printer Type menu key.
Step 3. Press Printer Type to access the Printer Type menu keys and press Auto to
make the NFA attempt to identify the connected printer.
When you select Auto as the Printer Type, the NFA responds in one of the
following three ways:
•
The Print Setup menu is displayed with the Auto key selected and no
new message is displayed in the display status line. This indicates that
the NFA recognizes the connected printer and no further setup is
required. As long as Auto remains selected in the Printer Type menu, the
NFA attempts to identify the printer when you press the front panel Print
key. The selected printer is displayed by pressing System, More 1 of 3,
Show System.
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Configuring a Printer with the NFA
•
The Print Setup menu is displayed with the Custom key selected and
one of the following diagnostic messages is displayed in the display
status line:
Unknown printer, Define Custom to set up printer
No printer response, Define Custom to set up printer
Invalid printer response, Define Custom to set up
printer
This indicates that the NFA is unable to automatically identify the
connected printer, and Custom is selected in the Printer Type menu.
Press Print Setup, Define Custom to select specific printer
characteristics such as the printer language (PCL3 or PCL5) and color
printing capability. Once you have set these characteristics to match
those of your connected printer, the printer setup process is complete. As
long as Custom remains selected in the Printer Type menu, the NFA
does not attempt to automatically identify the connected printer when
you press the front panel Print key.
•
The Print Setup menu is displayed with the None key selected and the
following message appears in the display status line:
Unsupported printer, Printer Type set to None
This indicates that the NFA recognizes the connected printer, but the
printer is not supported by the NFA. As long as None is selected in the
Printer Type menu, the NFA responds to any print command by
displaying the message Printer Type is None in the display status
line.
The Printer Type accesses the following keys:
None
None disables the NFA from attempting to print to a
printer. This is the appropriate setting if no printer is
connected to the NFA.
Custom
Custom allows you to access the Define Custom menu
keys. The Define Custom menu keys allow you to
specify printer characteristics such as PCL Level and
printer color capability.
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Auto
Chapter 5
Auto enables the NFA to automatically attempt to identify
the connected printer when the Print key is pressed or
when Printer Type is set to Auto.
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Configuring a Printer with the NFA
Testing Correct Printer Operation
When printer setup is complete test correct printer operation by pressing
Print Setup, Print (Screen) and then pressing the Print key to print a test
page.
If the printer is ready and printer setup is successful, a printout of the NFA
display is printed. If the printer is not ready, the message Printer
Timeout appears on the NFA display. Printer Timeout remains on the
display until the printer is ready or until you press ESC to cancel the printout
request.
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Front Panel Key Reference
This chapter describes each key and menu item contained within the user
interface of the NFA. The keys are listed in their key groupings and are listed
with their corresponding menu keys as they appear in the key menus.
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Front Panel Key Reference
MEASURE Keys
MEASURE Keys
Figure 6-1
Measure Key Group
Frequency/Points
This accesses the menu keys that control the measurement frequency range
and the number of discrete measurement points in the frequency range. It
also accesses the menus allowing you to set a spot measurement frequency
and create frequency lists.
The center frequency and frequency span, or start and stop frequency values
appear in the lower annotation on the display. This is dependent on which of
these options you have selected.
When entering a frequency value you specify units of Hz, kHz, MHz, or
GHz using the menu keys presented.
NOTE
The frequency range upper limits are model dependent. All models have a
lower limit of 10 MHz and each model’s upper limit is as follows:
•
•
•
The N8972A upper limit is 1.5 GHz.
The N8973A upper limit is 3.0 GHz.
The N8974A upper limit is 6.7 GHz.
•
The N8975A upper limit is 26.5 GHz.
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NOTE
Models, N8974A and N8975A have their default frequency ranges set to
avoid crossing the 3.0 GHz switch. See “3.0 GHz Mechanical Switch” on
page 18 for an explanation of this.
NOTE
When varying the External LO, the frequency limits are specified by you.
The limits applied depend on whether the LO or IF is being varied. See
“Making Extended Frequency Measurements” on page 135 for a further
explanation of this.
Figure 6-2
A Typical Frequency/Points Menu Map
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Freq Mode
This selects between swept, list and fixed frequency modes. The frequency
mode which is selected is displayed in the menu key.
The frequency modes available are:
•
Sweep where the frequencies are generated from the frequency range
selected and the number of measurement points.
•
List where the frequencies are taken from the frequency list.
•
Fixed where the measurement is taken at the fixed frequency.
Start Freq
This allows you to set the frequency at which the measurement sweep starts.
In the graphical format, the trace starts at the left side of the graticule. When
Start Freq is selected its value is displayed in the lower annotation.
Stop Freq
This allows you to set the frequency at which the measurement sweep stops.
In the graphical format, the trace stops at the right side of the graticule.
When Stop Freq is selected its value is displayed in the lower annotation.
Center Freq
This allows you to set the center frequency at which the measurement
frequency range is centered. When Center Freq is selected its value is
displayed in the left lower annotation.
Freq Span
This allows you to set the frequency range symmetrically about the centre
frequency. When Freq Span is selected its value is displayed in the right
lower annotation.
Fixed Freq
This allows you to set the frequency point used in fixed frequency
measurements. When Fixed Freq is selected its value is displayed in the left
and right lower annotation as start and stop values respectively.
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Points
This allows you to set the number of discrete equidistant measurement
frequency points at which measurements are made during Sweep frequency
mode. The maximum number of points allowed is 401. Default value is 11.
The number of points are shown at the bottom of the display.
NOTE
The maximum number of 401 points are conditional, as they are limited by
the frequency span. This is because the minimum resolution between any
two points is set at 10 KHz. Hence, to achieve 401 points, the frequencies
measurement range must be greater than 4 MHz.
Full Span
This changes the measurement span to the full span of the NFA showing the
full frequency range. The full span of the NFA is model dependant. See “The
Noise Figure Analyzer Features” on page 18 for your model’s frequency
range.
Freq List
This allows you access to a form to enter or edit a frequency list.
The frequency list allows you to enter a list of frequencies at which
measurements are to be made. Frequency lists are limited to 401 entry
points. The number of points are shown at the bottom of the display. The
frequencies are automatically sorted in ascending order.
Row Up
This allows you to select a particular entry in the table by
pressing this menu key to move up to its position in the
table one entry at a time.
Row Down
This allows you to select a particular entry in the table by
pressing this menu key to move down to its position in the
table one entry at a time.
Page Up
This allows you to move up the table entries in page
blocks.
Page Down
This allows you to move down the table entries in page
blocks.
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Add
This allows you to add a new entry. It adds the entry to the
bottom of the table after the last valid entry. It sequences
the entry in the correct ascending order when the entry is
terminated. To terminate an entry use the frequency unit
value keys presented to you.
Delete Row
This removes the highlighted row entry from the table.
Clear Table
This removes all entries from the table. You need to press
this menu key twice.
The first time you press the key you are prompted to press
it again. This two-stroke key press is a safety feature to
prevent you from accidentally pressing Clear Table and
erasing the table data.
Fill
244
This clears then fills the frequency list with current
frequencies generated by swept frequency mode.
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MEASURE Keys
Averaging/Bandwidth
This accesses the menu keys that control the measurement averaging and
bandwidth parameters.
Figure 6-3
Averaging/Bandwidth Menu Map
N8972A Menu
All Other Models Menus
Averaging
This allows you to enable or disable the averaging function. To enable the
averaging set the Averaging(On) function. To disable the averaging set the
Averaging(Off) function.
NOTE
If the averaging number is set to 1 and averaging is enabled, this gives the
same result as averaging disabled.
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Averages
This sets the number of times each data points is to be averaged. This is a
value between 1 and 999. The default value is 1, meaning that no averaging
is performed. You can either scroll using the RPG to the average value you
want, or enter the numerical value you want with the numerical keypad and
press Enter to terminate it. The value is annotated in the bottom of the
display.
Average Mode
This allows you to choose the type of averaging mode. To average at each
point enable the Average Mode(Point) function. To average at each sweep
enable the Average Mode(Sweep) function. See “Selecting the Averaging
Mode” on page 72 for an explanation on the difference between the two
modes.
NOTE
The sweep average function is not available on the N8972A.
Bandwidth
This allows you to set the measurement bandwidth to one of the following
values listed below. See page 71 for an explanation of measurement
bandwidth.
NOTE
•
100kHz
•
200kHz
•
400kHz
•
1MHz
•
2MHz
•
4MHz
The bandwidth menu key is unavailable on the N8972A and its bandwidth
value is set at the default 4MHz.
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Calibrate
This performs the internal calibration routine. The calibration is similar to a
measurement except that the device under test is not in the measurement
path. It is used to correct any noise added by the second stage test system.
You must press the Calibrate key twice before calibration starts. After the
first press you are presented with a popup dialogue box that prompts you to
press the calibrate key a second time to start the calibration, or to press
Escape to abandon the calibration.
The values generated during a calibration are used to correct subsequent
measurements as long as the calibration remains valid or until the next
calibration.
Figure 6-4
Calibration Warning Pop Up Box
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Meas Mode
This key accesses the Meas Mode Form, which allows you to select the
measurement mode of the NFA. You can choose which type of Device
Under Test and, if applicable, whether the LO is fixed or variable using this
form.
Use the Tab keys to highlight items in the form. When an item is highlighted
you can change its value. Its value is displayed in the highlighted area and in
the active function area.
Device Under Test This selects which type of DUT you want to measure.
•
Amplifier
•
Downconv
•
Upconv
System
Downconverter
This selects whether or not the downconverter is On or Off. This is only
accessible if the Device Under Test is set to Amplifier.
LO Mode
This selects whether the LO mode is Fixed or Variable.
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Figure 6-5
Meas Mode Menu Maps
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MEASURE Keys
Mode Setup
This key accesses the Mode Setup Form, which allow you to setup the
measurement mode of the NFA you selected under the Meas Mode key. This
allows you to choose the fixed frequency value, sideband, the NFA control
of the LO, and the LO power level to be used.
Use the Tab keys to highlight items in the form. When an item is highlighted
you can change it’s value. Its value is displayed in the highlighted area and
in the active function area.
IF Frequency
This allows you to set a fixed IF frequency when the LO Mode is set to
variable.
LO Frequency
This allows you to set a fixed LO frequency when the LO Mode is set to
fixed.
Sideband
This allows you to set the measurement side-band selection, where the
selected measurement mode allows, to either lower side-band (LSB),
upper side-band (USB), double side-band (DSB).
LO Control
This allows you to set whether the external LO is controlled by the NFA,
LO Control(On), or if the LO is set up manually, LO Control(Off). If you are
working with a fixed LO, you can set up the LO manually, however you are
required to enter the LO’s frequency value in the LO Frequency.
External LO Power This allows you to set the power level of the external LO. It only functions if
Level
the NFA’s LO control is set to LO Control(On). To enter a value, you can
either scroll using the RPG to the value you want, or enter the numerical
value you want with the numerical keypad. Press the units menu keys
presented to you to terminate it.
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Figure 6-6
Mode Setup Form with Sideband Menu Map Displayed
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ENR
This accesses a menu which allows you to select a noise source preference,
enter the ENR tables, specify a Tcold temperature, specify a spot Thot
temperature, and select a spot frequency ENR value.
Figure 6-7
ENR Menu Maps
ENR Mode
This switches between ENR Mode(Table) and ENR Mode(Spot) modes.
The default is ENR Mode(Table).
When ENR Mode(Spot) is enabled the ENR table data is ignored and a
single value specified by Spot ENR or Spot Thot is used.
Common Table
This switches between Common Table(On) and Common Table(Off)
modes. The default is Common Table(On).
When Common Table(On) is enabled, the same noise source ENR data is
used during both the measurement and calibration. When
Common Table(Off) is enabled, separate noise source ENR data is used for
the measurement and calibration.
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ENR Table
This allows you to enter, alter, or check data in the ENR table.
Edit Table
•
Row Up
•
Row Down
•
Page Up
•
Page Down
•
Add
•
Delete Row
•
Clear Table
The allows you to enter or edit an ENR table of
frequency/ENR pairs from which ENR values are
interpolated. See “Working with Tables” on page 45.
This allows you to select a particular entry in the table,
by pressing this menu key you move up to its position
in the table one row at a time.
This allows you to select a particular entry in the table,
by pressing this menu key you move down to its
position in the table one row at a time.
This allows you to move up the table entries in page
blocks.
This allows you to move down the table entries in
page blocks.
This allows you to add a new entry. It adds the entry to
the bottom of the table and sequences it in the correct
ascending frequency order when the row is complete.
To terminate the ENR Value entry use the unit keys
presented to you. You can also terminate using the
Enter key and it uses the dB unit value by default.
This removes the single row which is highlighted from
the table.
This removes all entries from the table. You need to
press this menu key twice.
The first time you press the key you are prompted to
press it again. This two-stroke key press is a safety
feature to prevent you from accidentally pressing
Clear Table and erasing the table data.
Serial Number
Chapter 6
This allows you to enter the serial number of the noise
source associated with the ENR table. To enter a value,
you use the Alpha Editor which is presented and the
numerical keypad. To complete the entry press the Prev
key. Its value is displayed in the highlighted area and in
the active function area.
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ID
Fill Table
From SNS
This allows you to enter the model number of the noise
source associated with the ENR table. To enter a value,
you use the Alpha Editor which is presented and the
numerical keypad. To complete the entry press the Prev
key. Its value is displayed in the highlighted area and in
the active function area.
This allows you to automatically upload the ENR Table
information from a SNS. This menu key is only active
when an SNS is connected. This information may already
be present, if the Auto Load ENR(On) is set.
Meas Table
This allows you to enter, alter, or check data in the measurement ENR table.
Cal Table
This allows you to enter, alter, or check data in the calibration ENR table.
NOTE
An ENR table can have a maximum of 81 entries.
Figure 6-8
Typical ENR Table with Table Entry Menu Map Displayed
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Spot
This allows you to select a specific ENR value or Thot value. The selected
value is applied across the entire frequency range during calibration and
measurement. To operate ENR Mode(Spot) must be enabled. The default
setting is Spot ENR(15.200 dB).
Spot Mode
This switches between the Spot Mode(ENR) and the
Spot Mode(Thot) modes. The default is
Spot Mode(ENR).
Spot ENR
This allows you to enter a spot ENR value which is
applied across the entire frequency range during
calibration and measurement. The value is applied when
Spot Mode(ENR) and ENR Mode(Spot) are enabled. The
default value is 15.200 dB.
The ENR value is entered using the numeric key pad and
terminated by selecting unit menu keys.
NOTE
The dB limits have a lower limit of -7.0 dB and an upper limit of 50.0 dB.
The K, C, and F limits are converted to the dB limits.
Spot Thot
This allows you to enter a spot Thot value which is applied
across the entire frequency range during calibration and
measurement. The value is applied when
Spot Mode(Thot) and ENR Mode(Spot) are enabled. The
default value is 9892.80 K.
The Thot value is entered using the numeric key pad and
terminated by selecting unit menu keys.
NOTE
The K limits have a lower limit of 0.00K and an upper limit of
29000290.0 K.
The C and F limits are converted to the K limits.
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Tcold
This menu key give access to the Tcold functions. When no Tcold functions
are enabled the default Tcold value of 296.50 K is used and the menu key is
set to Tcold(Default). When Tcold(User) is enabled, it uses your entered
User Value, or if an SNS is connected, the User Tcold From SNS value is
used. When Tcold(Auto) is enabled, it uses the SNS ambient temperature
value and updates this value after every measurement sweep. These SNS
features use the built-in SNS temperature sensor. The NFA can upload this
value and use it to calculate an accurate Tcold value.
SNS Tcold
This allows you to automatically upload the Tcold value
from the SNS built-in temperature sensor. The value
updates after every sweep. This feature is only enabled
when a SNS is connected.
When SNS Tcold(On) is selected the NFA uploads the
Tcold values from the attached SNS. Also, when
SNS Tcold(On) is selected the other Tcold menu keys are
unavailable. When the default SNS Tcold(Off) is selected
no automatic Tcold upload occurs.
User Tcold
This allows you to change the Tcold value. When
User Tcold(On) is selected it uses the value set in the
User Value. When the User Tcold(Off) is selected, the
NFA uses the default 296.50 K value.
User Value
This allows you to enter either a Tcold value manually, or
if an SNS is connected, by pressing the
User Tcold From SNS the value is automatically
uploaded from the SNS built-in temperature sensor. The
value is only valid when User Tcold(On) is enabled.
When entering a value manually use the numeric key pad
and terminated using one of the menu keys which are
presented to you.
User Tcold
From SNS
256
Pressing this menu key allows you to upload the Tcold
value from the SNS built-in temperature sensor. The value
is only valid when User Tcold(On) is enabled. This
feature is only enabled when a SNS is connected.
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SNS Setup
This allows you to select which type of noise source you prefer to use. Also,
if you are using an SNS, it allows you to choose to load it’s ENR values
automatically.
Preference
Selecting Preference(Normal) uses the +28V NOISE
SOURCE OUTPUT PORT and selecting
Preference(SNS) uses the SNS PORT, if an SNS is
connected. It is possible to have both an SNS and a +28V
driven normal noise source connected to the NFA at the
same time. However, the NFA’s +28V drive can only
drive one noise source at a time. Hence, you need to select
which noise source should be used. The default setting is
Preference(SNS) as this is typically expected to be the
preferred option. However, if an SNS is not connected the
NFA uses the +28V NOISE SOURCE OUTPUT PORT
even when Preference(SNS) is selected.
Auto Load ENR Selecting Auto Load ENR(On) enables the SNS to
automatically upload it’s ENR values and associated data
to the Common ENR Table. This happens when the NFA
is powered on or an SNS is connected to the SNS port.
Selecting Auto Load ENR(Off) disables the automatic
loading of the SNS data.
NOTE
When an SNS is connected and Auto Load ENR(On) enabled, the
Common Table(On) is set automatically. Hence, the SNS ENR data is
loaded into the common ENR table.
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DISPLAY Keys
Figure 6-9
Display Key Group
Scale
This key allows you to specify the units and limits for each active
measurement result type. The units are available in all display formats,
however, the limits only apply to the graph format.
Only the active measurement result graph units and limits are displayed. The
scale menu displayed is dependent on the active measurement result
selected. See Figure 6-10 showing the six measurement parameter scale
menu keys.
The graph limits and levels only affect how the data is displayed and do not
affect the measurement process or results.
Autoscale
Creates the graph limits to provide an optimum view of the result data.
NOTE
Autoscale does not scale a memory trace only the current data trace.
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Figure 6-10
Scale Menu Keys
Units
This sets the units used to display the data. It is dependent on which result
parameter you selected. The options are displayed in Table 6-1
Table 6-1
Result Parameter and Unit, Limit, and Scale/Div Type
Result Parameter
Units, Limits, and Scale/Div
Noise Figure
dB or Linear
Gain
dB or Linear
Y Factor
dB or Linear
Teffective
K, C or F
Phot
dB or Linear
Pcold
dB or Linear
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Upper Limit
This sets the upper graph limit on the y-axis. The linear scale values use
engineering multipliers to terminate the entry, see Figure 6-11. As the scale
per division values are coupled to the upper limit, setting the upper limit
causes the scale per division value to be adjusted.
Lower Limit
This sets the lower graph limit on the y-axis. The linear scale values use
engineering multipliers to terminate the entry, see Figure 6-11. As the scale
per division values are coupled to the lower limit, setting the lower limit
causes the scale per division value to be adjusted.
Ref Level
This allows you to enter a reference level value. The linear scale values use
engineering multipliers to terminate the entry, see Figure 6-11. It is
displayed as a horizontal line in the graph, if the Display Ref(On) is
enabled. To enter a value, use the numerical keypad.
NOTE
The Ref Level value can only be set within the Upper Limit value and
Lower Limit value.
Display Ref
This allows you to show or hide the reference level on the graph. To show
the reference level set Display Ref(On). To hide the reference level set
Display Ref(Off), this is the default setting.
Scale/Div
This sets the units per division on the y-axis. The linear scale values use
engineering multipliers to terminate the entry, see Figure 6-11. Setting this
causes the upper and lower limits to be adjusted as the items are coupled.
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Figure 6-11
Scale Linear Termination Menu Keys
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Format
This accesses menu keys to select which display format you want the
measurement data presented. You can choose between graph, table and
meter format.
When Format is set to Graph, you can combine the two graphs, save a trace
to volatile memory and recall it later. Also, the annotation and graticules can
be switched off or on.
Figure 6-12
Format Menu Keys
Format
This selects between Format(Graph) where a graphical display is shown,
Format(Table) where the measurement results are shown in tabular form, or
Format(Meter) where the measurement results are shown in single
frequency point result display format. The default setting is Graph.
Combined
When Combined(On) is enabled it combines the upper and lower graphs
from a dual graph display into a single graphical display. It overlays both
upper and lower graphs simultaneously. When Combined(Off) is enabled
the graphs are not combined, this is the default setting.
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Trace
The Trace menu key only becomes available after you have pressed the
Data->Memory menu key.
When Trace(Data) is enabled, it displays the current measurement trace.
This is the default setting.
When Trace(Memory) is enabled, it displays the measurement trace you
saved to memory when the Data->Memory menu key was pressed.
When Trace(Data&Memory) is enabled, it displays the measurement trace
you saved to memory when the Data->Memory menu key was pressed and
the current measurement trace. This allows you to compare two traces.
Data->Memory
When the Data->Memory menu key is pressed the current trace is stored in
volatile memory and remains there until change the measurement parameter,
you switch the NFA off, preset it, or press the Data->Memory menu key
again saving another trace. After you have pressed the Data->Memory menu
key the Trace menu key becomes available. The Data->Memory menu key
is only available after a complete sweep of data is made.
Graticule
When Graticule(On) is enabled, it switches the graph graticule on. This is
the default setting. When Graticule(Off) is enabled, it switches the graph
graticule off and the graticule is removed from the graph.
Annotation
When Annotation(On) is enabled it switches the screen annotation
surrounding the graphs on, and the annotations are displayed. This is the
default setting. When Annotation(Off) is enabled it switches the screen
annotation surrounding the graphs off and the annotations are removed from
the display. However, menu key annotation remains on the screen.
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Result
This key allows you to specify which measurement result parameter you
want to display in the active measurement. This is applicable to all display
formats.
NOTE
You cannot make the same two measurement result active, as each
measurement result type selected must differ from the other.
NOTE
The result menu shows the current, active measurement result. To obtain the
other result parameter use the
Figure 6-13
key.
Result Menu Key
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Noise Figure
This selects noise figure as the measurement result.
Gain
This selects gain as the measurement result.
NOTE
This gain measurement result is only valid after a calibration has been
performed and Corrected(On) is selected.
Y Factor
This selects Y-Factor as the measurement result.
Teffective
This selects equivalent temperature as the measurement result.
Phot
This selects hot power density as the measurement result.
Pcold
This selects cold power density as the measurement result.
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Marker
This accesses the marker control keys which select the marker type,
placement, number, and switch them on and off. Markers are
diamond-shaped characters that identify points of traces. Up to four pairs of
markers are available. They can be distributed on the various traces and may
appear on the display simultaneously; only one pair can be controlled at a
time. The marker that is controlled is called the “active” marker.
Above the graph, all the enabled marker’s results are displayed. When a
marker is activated, its frequency value is displayed in the active function
area.
Figure 6-14
Marker Menu Maps
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Marker
Selects one of the four possible marker pairs, Marker(1), Marker(2),
Marker(3), and Marker(4). Only one of the markers can be active, although
they can, if required, all be enabled. To make a marker active, you need to
underline the marker, for example, Marker(1) is active and while active it’s
frequency value is displayed in the active function area.
State
Off
This switches off an active marker and removes it from
the graph. It also removes the marker annotation from the
display. This is the default state.
Normal
Places a single marker on the graph's trace. If a marker
has been displayed previously and is reactivated, the
marker is enabled at the marker's previously selected
position. The marker number is indicated above the
marker.
Use the RPG to control the position of the marker. Its
frequency value is displayed in the active function area
and frequency and measurement parameter values are
reported above the graph.
Pressing Normal when the Delta or Band Pair function is
enabled, switches off the reference marker.
Delta
Activates a second marker at the position of the first
marker. It is identified as a reference marker and its
position is fixed. (If no marker is present, the marker
appears at the center of the graph, or if the marker has
been previously active it appears in the last marker
position) The marker number is indicated above the delta
marker, and the same number is indicated with an R (for
example, 1R) above the reference marker. Use the RPG to
position the delta marker.
The delta marker’s frequency value is displayed in the
active function area. Also frequency and measurement
parameter values are reported above the graph to indicate
the difference between the two markers. The reference
marker's position remains fixed until delta is disabled.
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Band Pair
Enters a mode that allows adjustment of the two markers
independently. It is similar to the delta marker mode,
except you can choose to move the normal marker or the
reference marker. Pressing Band Pair(Ref) and
Band Pair(Normal) menu keys, switches between the
reference and normal markers. The reference marker
number is indicated with a number and an R (for example,
1R) and the normal marker is indicated with a marker
number.
The band pair marker’s frequency value is displayed in
the active function area. Also the frequency and
measurement parameter values are reported above the
graph to indicate the difference between the two markers.
Band Pair
This menu key is only accessible when State(Band Pair) has been selected.
Band Pair(Ref) and Band Pair(Normal) menu keys, switch between the
reference and normal markers. The reference marker number is indicated
with a number and an R (for example, 1R) and the normal marker is
indicated with a marker number. Use the RPG to position the currently
selected marker.
Trace
This menu key becomes active after Data->Memory has been pressed. It is
used to place a marker on either the data or memory trace. Trace(Data)
places a marker on the active trace. This is the default setting.
Trace(Memory) places a marker on the memory trace.
For example, when the recalled and active traces are both displayed,
pressing this key causes the marker to hop from the data trace to the memory
trace.
NOTE
If you disable the memory trace display with a marker on, the marker
disappears
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Search
This menu key allows you access to a further menu where you can configure
a marker search on the trace. The type of search is dependent on the setting
type.
Marker
The Marker menu key allows you to change the active
marker. See “Marker” on page 267 for an explanation.
Search Type
When the Search Type menu key is pressed a further
optional choice can be made. The options are: •
When Search Type(Min) is enabled, the active marker
is placed at the minimum point of the trace.
This key is not accessible when the Marker state is
Band Pair.
•
When Search Type(Max) is enabled, the active
marker is placed at the maximum point of the trace.
This key is not accessible when the Marker state is
Band Pair.
•
When Search Type(Pk-Pk) is enabled, the active band
pair markers are placed on the highest and lowest trace
points. The reference marker is placed on the highest
peak while the normal marker is placed on the lowest
trough. Its frequency and measurement parameter
values are reported above the graph to indicate the
difference between the two markers.
This key is only accessible when the Marker state is
Band Pair.
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Continuous
NOTE
If you are searching continuously the markers have additional annotation
which identifies which marker is the minimum and the maximum. The
annotation is “∨” a minimum, “∧” a maximum. If you change the active
graph the annotation remains on the original graph.
Find
Markers All Off
When Continuous(On) is enabled, the active marker
continuously finds the maximum, minimum, or
peak-to-peak on the trace as successive sweep results are
reported. This is dependent on which search type is
selected. When Continuous(Off) is enabled, the marker
search is controlled by the Find menu key.
Pressing the Find menu key manually places an active
search marker. This functions when Continuous(Off) and
a Marker is enabled. The annotation displays the
frequency and measurement parameter differences. Also
in the Find mode the marker’s frequency value is
displayed in the active function area.
This switches off all of the markers, including the marker annotation.
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CONTROL Keys
Figure 6-15
Control Key Group
Loss Comp
This key accesses features which allow the NFA to compensate for losses,
for example, due to additional cabling, before and/or after the DUT’s
measurement, by allowing you to specify the compensation loss. This loss
can either be the same fixed value over the whole frequency span or it can
vary across the frequency span using values specified in a table.
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Figure 6-16
Loss Compensation Menu Keys
Setup
This accesses the Loss Compensation Setup form.
Figure 6-17
Loss Compensation Setup Form
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You use the Tab keys to highlight items in the form. When an item is
highlighted its value or option is also displayed in the menu key, allowing
you to change its status or value.
Before DUT
This controls the compensation before the device under
test. It is either,
•
Off, where there is no compensation before device
under test. The default status is Off.
•
Fixed, where the Before DUT Fixed Value
compensation is used.
•
Before DUT
Fixed Value
Before
Temperature
After DUT
Table where the values in the Before DUT Table
are used.
This sets the amount of compensation, before the device
under test, as a fixed value. This is only valid if the
Before DUT(Fixed) is enabled. You can enter the value as
dB or linear. However, the linear value is converted to dB.
The lower limit is -100.000 dB and the upper limit is
100.000 dB. The default value is 0.000 dB.
This sets the temperature of loss compensation, before the
device under test, as a fixed value. This is only valid if
Before DUT is enabled. You can enter the value as K, C,
or F. However, the C and F values are converted to K. The
lower limit is 0.00K and the upper limit is 29,650,000.0K.
The default value is 0.00K.
This controls the compensation after the device under test.
It is either,
•
Off, where there is no compensation after device under
test. The default status is Off.
•
Fixed, where the After DUT Fixed Value
compensation is used.
•
Table where the values in the After DUT Table are
used.
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After DUT
Fixed Value
After
Temperature
274
This sets the amount of compensation, after the device
under test, as a fixed value. This is only valid if
After DUT(Fixed) is enabled. You can enter the value as
dB or linear. However, the linear value is converted to dB.
The limit and default values are the same as Before DUT.
This sets the temperature of loss compensation, after the
device under test, as a fixed value. This is only valid if
After DUT is enabled. You can enter the value as K, C, or
F. However, the C and F values are converted to K. The
limit and default values are the same as Before DUT.
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Before DUT
Table
Figure 6-18
This accesses the Loss Compensation Before DUT Table form.
This allows you to enter a Loss table of frequency/value pairs from which
loss values are interpolated. See “Working with Tables” on page 45 or the
following description.
Loss Compensation Before DUT Table
You use the Tab keys to highlight items in the form. When an item is
highlighted it is also displayed in the menu key, allowing you to change its
status or value.
Row Up
This allows you to select a particular row in the table, by
pressing this menu key you move up to its position in the
table one entry at a time.
Row Down
This allows you to select a particular row in the table, by
pressing this menu key you move down to its position in
the table one entry at a time.
Page Up
This allows you to move up the table entries in page
blocks.
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Page Down
This allows you to move down the table entries in page
blocks.
Add
This allows you to add a new entry. It adds the entry to the
bottom of the table and sequences it in the correct
ascending order of frequency when it is terminated.
To terminate the value entry use the unit keys presented to
you. You can also terminate the loss value using the Enter
key and it uses the dB unit value by default.
Delete Row
This removes the highlighted single row entry from the
table.
Clear Table
This removes all entries from the table. You need to press
this menu key twice.
The first time you press the key you are prompted to press
it again. This two-stroke key press is a safety feature to
prevent you from accidentally pressing Clear Table and
erasing the table data.
After DUT Table
This accesses the Loss Compensation After DUT Table form.
This allows you to enter an Loss table of frequency/value pairs from which
loss values are interpolated. See “Working with Tables” on page 45 or the
descriptions under the “Before DUT Table” on page 275.
NOTE
A Loss Compensation table can have a maximum of 201 entries.
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Limit Lines
The limit lines mark boundary limits of a trace. Limit lines feature four
independent lines numbered from 1 to 4. Limit line 1 and 2 are associated
with the upper graph, and limit line 3 and 4 are associated with the lower
graph. The limit lines can be set to inform you when the trace of interest
crosses one of the limit lines. The limit lines can be set as an upper or lower
limit. They can also be displayed on the their associated graph.
Figure 6-19
Typical Limit Line Menu Map
Limit Line
Selects one of the four possible limit lines. Limit Line(1›) and Limit Line(2›)
are associated with the upper graph trace, and Limit Line(3fl) and
Limit Line(4fl) are associated with the lower graph trace. The selected limit
line is underlined and the other limit line menu items apply to it.
Type
This menu key sets the selected limit line to, either Type(Upper) or
Type(Lower). The limit line is tested against the trace if Test(On) is enabled.
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Test
This menu key becomes active after limit line data has been entered. It sets
the selected limit line to test against the trace. To enable the test, set
Test(On). If a limit line failure occurs, the result is reported in the upper left
hand corner of the display annotation. To disable the test, set Test(Off). This
is the default setting.
Editor
This accesses a Limit Line editor which allows you to enter or edit the
selected limit line. Figure 6-20 shows the editor.
Limit lines are limited to 201 frequencies. The limit line entries are
automatically sorted in ascending frequency order, after the point has been
entered. The limit unit is the unit of the selected graph.
Figure 6-20
Limit Line Editor with Table Entry Menu Map
Frequency
This sets the frequency value of the current entry.
Limit
This sets the limit value of the current entry. The limit line
is a unitless value. The values are dependent on the
associated graphical limits.
Connected
This is used to connect the current point to, or disconnect
the current point from the previous point. Setting it to
Yes, connects the point to the previous point. Setting it to
No, the point is not connected to the previous point.
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See “Working with Tables” on page 45 or the following descriptions on how
to enter values into a table.
•
Row Up
•
Row Down
•
Page Up
•
Page Down
•
Add
•
Delete Row
•
Clear Table
This allows you to select a particular entry in the table,
by pressing this menu key you move up to its position
in the table one row at a time.
This allows you to select a particular entry in the table,
by pressing this menu key you move down to its
position in the table one row at a time.
This allows you to move up the table entries in page
blocks.
This allows you to move down the table entries in
page blocks.
This allows you to add a new entry. It adds the entry to
the bottom of the table and sequences it in the correct
ascending frequency order when the row is complete.
This removes the single row which is highlighted from
the table.
This removes all entries from the table. You need to
press this menu key twice.
The first time you press the key you are prompted to
press it again. This two-stroke key press is a safety
feature to prevent you from accidentally pressing
Clear Table and erasing the table data.
Display
This menu key becomes active after limit line data has been entered. It
displays the selected limit line on the graph. To enable the limit line display,
set Display(On). To disable the limit line display, set Display(Off), this is the
default setting.
Limit Lines All
Off
This switches off all of the limit lines, including any limit line test result and
annotation.
NOTE
When a limit line is switched off the limit line data is unchanged and can be
retrieved if the limit line is switched on again.
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Full Screen
This allows the measurement window to expand over the entire display
removing the menu keys, the active window annotation, and the display
status line annotation. This functions in all formats, graph, table and meter.
Press the Full Screen key again to return to the previous display. All other
key presses are ignored except; Zoom, Next Window, Save Trace, Help,
Preset, Print, Power Standby, and the Viewing Angle keys.
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Corr
This key allows you to switch corrected measurements off or on. The default
status is dependent on whether a calibration has been made previously.
You can change the choice of input attenuation of the NFA used during
calibration, allowing you to make the calibration faster, or measure higher
gain DUTs.
Figure 6-21
N8972A and N8973A Corrected Menu Maps
Corrected
This allows you to select between corrected and uncorrected results.
You have the option of doing the measurement with the Corrected(On) or
the Corrected(Off). The correction uses the calibration data of the second
stage and accounts for errors associated with this.
After you have made a calibration the annotation Corr is displayed at the
bottom right corner of the display.
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NOTE
If you change the frequency range to greater than the current calibration, the
NFA changes to Uncorr. If you want corrected measurements over a greater
range, you need to re-calibrate the NFA again before making this
measurement. If you change the frequency range to less than the current
calibration, the NFA changes to a yellow Corr. This demonstrates the NFA
is using interpolated results and interpolated errors may be introduced.
Input Cal
The menu key gives you access to menu keys allowing you to set the
maximum and minimum attenuator values.
Figure 6-22
N8974A and N8975A Microwave Attenuator Menu Maps
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NOTE
On the N8972A and N8973A models there are no Min mW Atten and
Max mW Atten menu keys. The microwave attenuator is only available on
the N8974A and N8975A models.
Min Atten
This menu key allows you to change the RF attenuator’s
minimum input attenuation during calibration. The RF
attenuator’s frequency range is less than or equal to
3.0 GHz. The choice is from 0dB to 40dB in 5 dB steps.
The default value is 0dB.
Max Atten
This menu key allows you to change the RF attenuator’s
maximum input attenuation during calibration. The RF
attenuator’s frequency range is less than or equal to
3.0 GHz. The choice is from 0dB to 40dB in 5 dB steps.
The default value is 20dB.
Min mW Atten
This menu key allows you to change the microwave
attenuator’s minimum input attenuation during
calibration. The microwave attenuator’s frequency is
greater than 3.0 GHz. The choice is from 0dB to 30dB in
15 dB steps. The default value is 0dB.
Max mW Atten
This menu key allows you to change the microwave
attenuator’s maximum input attenuation during
calibration. The microwave attenuator’s frequency is
greater than 3.0 GHz. The choice is from 0dB to 30dB in
15 dB steps. The default value is 0dB.
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Sweep
Sweep Mode
This menu key is used to control the NFA’s measurement repetition, so that it
is performed once or multiple times.
To set the measurement to perform once, enable Sweep Mode(Single). To
set the measurement to repeat continuously, enable Sweep Mode(Cont), this
is the default setting.
Figure 6-23
Sweep Menu Map (N8974/5A Models)
Manual Meas
This allows you access to the Manual Measurement menu keys. This also
allows you to manually set the RF attenuator, the IF attenuator, and the
microwave attenuator on the N8974/5A models. See “Manual
Measurements Procedure” on page 133.
NOTE
The microwave attenuator is only available on the N8974A and N8975A
models.
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NOTE
On the N8972A and N8973A models the RF/mW Att menu key is labelled
RF Att. Also, there is not a Fixed mW Att menu key.
Manual State
This allows you to either enable the Manual State(On) or
disable the Manual State(Off) in the Manual
Measurement Mode. The default status is
Manual State(Off) and the other menu keys in the Manual
Measurement Menu are disabled, except the RF
attenuator, microwave attenuator, and IF attenuator keys.
Accept
Press this menu key when you are satisfied that the
reading is sufficiently settled to be used in the manual
measurement calculations. When pressed, the NFA will
use the current power reading in the manual measurement
calculations.
This menu key is disabled when Manual Meas(Off) is
selected.
Calibration
This menu key allows you to control whether the NFA is
performing a calibration or measurement. Selecting
Calibration(On) a calibration is performed at a selected
frequency point. Selecting Calibration(Off) a
measurement is performed at a selected frequency point.
The default status is Calibration(Off).
This menu key is disabled when Manual Meas(Off) is
selected.
Noise Source
This allows you to switch the noise source on and off.
Selecting Noise Source(On) a Phot measurement is
performed at a selected frequency point. Selecting
Noise Source(Off) a Pcold measurement is performed at
a selected frequency point. The default status is
Noise Source(Off).
This menu key is disabled when Manual Meas(Off) is
selected.
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RF/mW Att
This is used to control the RF and microwave attenuator
setting. Selecting RF/mW Att(Auto) enables the RF
and/or microwave attenuator auto-ranging. This is the
default value. Selecting RF/mW Att(Hold) enables the
current RF attenuator setting to be held until the selection
is changed. Selecting RF/mW Att(Fixed) enables the
values specified in Fixed RF Att value or Fixed mW Att
value to be used.
IF Att
This is used to control the IF attenuator setting. Selecting
IF Att(Auto) enables the IF attenuator auto-ranging. This
is the default value. Selecting IF Att(Hold) enables the
current IF attenuator setting to be held until the selection
is changed. Selecting IF Att(Fixed) enables the values
specified in Fixed IF Att value to be used.
Point
This allows you to specify the frequency point at which
you want to make the measurement. The points are the
number of sweep points in the frequency settings.
This menu key is disabled when Fixed Freq or
Manual Meas(Off) is selected.
Fixed RF Att
This allows you to specify a fixed value of the RF
attenuator, where the frequency is less than or equal to
3.0 GHz. It is applied when RF/mW Att(Fixed) is
enabled.
The choice is from 0dB to 40dB with a 5 dB step option.
The default value is 0dB.
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NOTE
The Fixed mW Att menu key is only available on the N8974A and N8975A
models.
Fixed mW Att
This allows you to specify a fixed value of the microwave
attenuator, where the frequency is greater than 3.0 GHz. It
is applied when RF/mW Att(Fixed) is enabled.
The choice is from 0dB to 30dB with a 15 dB step option.
The default value is 0dB.
Fixed IF Att
This allows you to specify a fixed value of the IF
attenuator. It is applied when IF Att(Fixed) is enabled.
The maximum attenuation allowed is 70 dB. The default
value is 59 dB.
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Restart
When a measurement is in progress and the Restart key is pressed, it stops
the measurement and a new one is started. Depending on the sweep setting,
the measurement is either made once or continuously.
When in Manual Measurement Mode pressing Restart causes the
measurement to start again and all the previous data is lost.
NOTE
The Restart key can also be used to stop a calibration routine.
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SYSTEM Keys
Figure 6-24
System Key Group
System (Local)
This key has two functions. When the instrument is in remote mode pressing
this key returns it to local mode.
Pressing System (Local) after the NFA has been placed in the remote mode,
places the NFA in the local mode and enables front panel control. During
remote operation, R appears in the upper-right corner of the screen. A T, L or
S may appear during remote operation, indicating talk, listen, or service
request. Pressing the System (Local) key removes the R symbol in the
upper-right corner.
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Figure 6-25
System(Local) Menu Maps
Remote Port
This allows you to select between Serial and GPIB remote modes.
You have the option of using the Remote Port(Serial) or the
Remote Port(GPIB)
NOTE
The NFA needs to be power cycled before the remote port change takes
effect.
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GPIB
The GPIB menu key accesses the System GPIB Form. This allows access
to the GPIB address of the NFA and the LO GPIB related addresses.
Figure 6-26
System GPIB Form with a Menu Displayed
You use the Tab keys to highlight items in the form. When an item is
highlighted it is also displayed in the menu allowing you to change its value.
Noise Figure
Analyzer Address This sets the instrument GPIB address. Valid addresses
are from 0 to 29. The default address is 8.
External LO
Address
This sets the GPIB address of the External LO attached to
the LO GPIB. Valid addresses are from 0 to 30. The
default address is 19
LO GPIB Address This sets the address through which devices, attached to
the LO GPIB, communicate with the NFA. Valid
addresses are from 0 to 30. The default address is 8.
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Serial
The Serial menu key accesses the System Serial Form. This allows
access to the Serial port configuration of the NFA.
You use the Tab keys to highlight items in the form. When an item is
highlighted it is also displayed in the menu allowing you to change its value.
Figure 6-27
System Serial Form with Baud Rate Menu Map Displayed
Data Terminal
Ready
Request To
Send
292
This sets the DTR line control. To disable the serial port
and de-assert the DTR, press OFF, this is the default
setting. To enable the serial port and assert the DTR, press
ON. To enable the driver to use the DTR for receive data
pacing, press IBF.
This sets the RTS line control. To disable the serial port
and de-assert the RTS, press OFF, this is the default
setting. To enable the serial port and assert the RTS, press
ON. To enable the driver to use the RTS for receive data
pacing, press IBF.
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Baud
This sets the baud rate. The following list is the Baud rate
values. The default setting is 9600.
•
1200
•
2400
•
4800
•
9600
•
19200
•
38400
Receive Pacing This sets the receive pacing handshake characters. To
disable the software receive pacing, press NONE, this is
the default setting. To enable the XON/XOFF characters,
press XON/XOFF.
Transmit Pacing This sets the transmit pacing handshake characters. To
disable the software transmit pacing, press NONE, this is
the default setting. To enable the XON/XOFF characters,
press XON/XOFF.
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External LO
This menu is used to set the External LO limits and commands. The
frequency and power limits that are included in the system LO menu to stop
the External LO from being controlled outside its working range. The NFA
is unable to check the validity of the inputs.
Figure 6-28
External LO Menu Map
Command Set
This sets the External LO command language. Set the
Command Set(SCPI) to use the built in commands to
drive an LO which is SCPI compliant. Set the
Command Set(Custom) when the External LO is not
SCPI compliant and enter the custom command strings.
LO Commands
This accesses the External LO Commands Form.
This form allows you to enter the commands used to
control a non-SCPI-compliant External LO. To enter a
command use the Alpha Editor and the numeric keypad.
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NOTE
When entering an External LO Command, spaces after the prefix and before
the suffix may be important.
Figure 6-29 External LO Commands Form with Menu Keys
•
Power Prefix, sets the prefix for the command used to
set the External LO's power level.
•
Power Suffix, sets the suffix for the command used to
set the External LO's power level.
•
Freq Prefix, sets the prefix for the command used to
set the External LO's frequency.
•
Freq Suffix, sets the suffix for the command used to
set the External LO's frequency.
•
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Auxiliary, other commands required to properly
control the External LO (for example, to preset the LO
or to put the LO in a CW operation).
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Settling Time
This sets the settling time of the NFA’s command to the
External LO. This is used as a settling period after
commands are sent to the LO. Valid settling times are
between 0 ms and 100 s. The default value is 100 ms.
Min Freq
This sets the minimum frequency the NFA expects the
External LO to have. The default value is 10 MHz.
Max Freq
This sets the maximum frequency the NFA expects the
External LO to have. The default value is 40.0 GHz.
Multiplier
This sets the value of the External LO frequency
multiplier. The default value is 1.
Alignment
Accesses the Alignment menu keys which align the internal circuitry of the
NFA and allow you to choose the alignment mode.
Figure 6-30
Alignment Menu Map
Alignment
296
Selecting Alignment(On) enables the automatic
alignment of the NFA, this is the default setting. Selecting
Alignment(Off) disables automatic alignment.
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IMPORTANT
In unstable temperature environments or where a lot of averaging is being
applied, it is better to align more often. Hence, point mode should be more
accurate.
Alignmnt Mode Selecting Alignmnt Mode(Sweep) enables the alignment
of the NFA to align at the beginning of a sweep. This is
the default setting. Selecting Alignmnt Mode(Point)
enables alignment to align at each point of the sweep.
Align YTF
Save YTF
Alignment
This aligns the tuning current of the YIG Tuned Filter
(YTF) against frequency. To avoid an accidental key press
you need to press Align YTF menu key again.
This saves the YTF alignment data to persistent memory.
This is stored in the NFA’s non-volatile RAM and remains
there after a preset or a power cycle. It also remains in
memory after Restore Sys Defaults menu key is pressed.
To avoid an accidental key press you need to press
Save YTF Alignment menu key again.
NOTE
On N8972A and N8973A models the Align YTF and Save YTF Alignment
menu keys are unavailable.
Show Errors
Accesses a display of the last 10 errors reported. The most recent errors
appear at the top of the list.
Clear Error Queue Clears the error queue in the Show Errors display.
Show System
Displays the instrument model name, product number, serial number,
host ID, firmware revision number, bootrom revision, and amount of RAM
and ROM. Also displayed are the hardware modules in each card slot,
options fitted, the printer type, and a time counter.
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Show Hdwr
Displays the instrument model name, product number, serial number,
firmware revision number, bootrom revision, and amount of RAM and
ROM. Also, displayed are the assembly name and where appropriate the part
number, serial number and version numbers of the hardware modules in your
NFA.
Power On/Preset Accesses menu keys to change the setting of the NFA state which is recalled
at power on. The power on preset system controls the power on state of the
NFA.
Figure 6-31
Power On/Preset Menu Map
Power On
298
Determines the preferred state of the NFA when the NFA
is powered on. If the function is set to Power On(Preset),
the power on state of the NFA is the same as it is after the
Preset is pressed. If the function is set to Power
On(Last), then the state that the NFA was in when it was
powered off is recalled when it is powered on.
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NOTE
The setting Power On is not changed by pressing Preset.
Preset
This sets the preset state to be used when
Power On(Preset) is the selected state. The NFA is put in
the preset state by pressing the Preset key. Selecting
Preset (Factory) allows the NFA to be in the default
configuration originally set at the factory. Selecting
Preset (User) allows the NFA to be in the settings defined
by the Save User Preset key. See “Preset” on page 309
in this chapter.
Save User Preset Saves the current instrument active state of the NFA into
your Preset register for recall on Preset if Preset(User) is
selected.
Restore Sys
Defaults
Pressing this menu key restores the NFA to the factory default settings. This
key needs to be pressed twice, as it has this safety feature to stop you
accidently pressing this key.
The restored items are, for example, the GPIB address, that are unaffected
by a power cycle or a preset.
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Time/Date
Accesses menu keys used to set and display the real-time clock in the Date
Window.
Figure 6-32
Time/Date Menu Map
Time/Date
Enable Time/Date(On) to switch the display of the
real-time clock on, or enable Time/Date(Off) to switch the
display of the real-time clock off.
Date Mode
Enable Date Mode(MDY) to display the date in a
month-day-year format, or enable Date Mode(DMY) to
display the date in a day-month-year format.
Set Time
This allows you to set the time of the real-time clock.
Enter the time in 24 hour HHMMSS format, using the
numeric keypad and pressing Enter to terminate it. Valid
hour (HH) values are from 00 to 23. Valid minute (MM)
and second (SS) values are from 00 to 59.
Set Date
This allows you to set the date of the real-time clock.
Enter the date in the YYYYMMDD format using the
numeric keypad and press Enter. Valid year (YYYY)
values are 0000 through 9999. Valid month (MM) values
are from 01 to 12, and valid day values are from 01 to 31.
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Diagnostics
Accesses the Front Panel Test menu key.
Front Panel Test Allows you to verify the functionality of each front panel
key (except Preset). The number next to each key name
increments once each time the key is pressed. Rotating the
RPG causes the number of pulses to be counted. Press
Esc to exit.
Service
Accesses the Service menu keys which requires a password for further
access. For information, refer to the Noise Figure Analyzers NFA Series
Performance Verification and Calibration Guide.
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File
This accesses the menu keys used to load, save, and manage data on a floppy
disk or the internal NFA drives. The file system consists of two DOS
compatible volumes. The first, volume A, is the floppy disk. The second,
volume C, is the internal flash file system.
The file menu keys also access dialog boxes appropriate for the selected
function. You can store and retrieve information to and from files in the file
systems and perform file system management functions. The Tab keys allow
you to move between the dialog box fields and set up a desired operation.
Press the Enter key to execute an operation.
The file select submenu changes in format depending on where it was
entered from. From the Load File and File Manager menus it has a single
softkey which is used to select a file name from a scrollable list of files.
From the Save File menu it uses the Alpha Editor to enter new file names. It
also numbers the files with default names sequentially.
Load
Accesses menu keys that allow you to load ENR values, states, limits,
frequency lists, loss compensation tables into the NFA from a floppy (A:)
drive or internal flash (C:) drive. To load a file, use the following steps:
1. Select the type of data you wish to load by pressing the appropriate menu
key. For example, if you select Limits, you also have to select which
limit line 1, 2, 3, or 4.
2. The drive letter name is activated in the Path dialog box. Select the
source of the data. Select the desired drive with the Select key. If you are
already in a drive, press Select while “..” is active to select a different
drive. Use the  and  keys or the RPG to activate the desired drive.
Press Select.
3. When you are ready to load the data, press Enter.
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ENR
ENR files contain tables of ENR/frequency pairs used to
characterize a noise sources. Files of this type have the
three letter suffix (ENR). You need to decide whether the
ENR file is either, a Meas Table or a Cal Table by
pressing the appropriate menu key.
State
State files contain the instrument settings. Loading a state
file restores the settings to the previously saved values.
Files of this type have the three letter suffix (STA).
Limits
Limits files contain limit line specifications and provides
data sets to determine whether a trace has crossed the
limit line specifications. You need to decide whether the
limits file is either, a limit line 1, 2, 3, or 4, by pressing the
appropriate menu key. Files of this type have the three
letter suffix (LIM).
Frequency List Frequency list files contain specified list of frequencies at
which measurements are to be made. Files of this type
have the three letter suffix (LST).
Loss
Loss files contain loss compensation data. You need to
decide whether the loss file is either a Before Table or
After Table by pressing the appropriate menu key. Files of
this type have the three letter suffix (LOS).
The NFA can also load S2P file formats. The NFA accepts
any files with the following extensions: S2P, S1, and S2.
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Save
Accesses menu keys that allow you to save the NFA’s ENR, states, traces,
limits, frequency lists, loss compensation tables, and screen data to a floppy
(A:) drive or internal flash (C:) drive.
NOTE
The Save Menu is similar to the Load Menu, except that it supports two
additional file types, these are, trace and screen. It also only allows you to
save loss compensation as .LOS files. The S2P formats are only available to
load into the NFA.
To save a file, use the following steps:
1. Select the type of data you wish to save by pressing the appropriate menu
key. For example, if you select ENR, you need to select either
Meas Table or Cal Table.
2. If appropriate, in the Format dialog box, select the desired format.
3. If the auto-selected name is not acceptable, enter a name using the Alpha
Editor menu keys. File names are limited to eight characters.
4. The Path dialog box becomes active, allowing you to change the
destination drive of the data. Select the desired drive with the Select key.
If you are already in a drive, press the Select key while “..” is activated
to select a different drive. Use the  and  keys or the RPG to activate the
desired drive. Press Select.
5. When you are ready to save, press Enter.
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ENR
ENR files contain tables of ENR/frequency pairs used to
characterize a noise sources. ENR allows you to save an
ENR table in memory. You need to decide whether the
ENR file is a Meas Table, a Cal Table, or an SNS table
by pressing the appropriate menu key.
State
State files contain the instrument settings. State allows
you to save an NFA state in memory.
Trace
A trace is saved in a Comma Separated Value (CSV)
format, and is readable by a spreadsheet on your PC.
However, it cannot be loaded back into the NFA.
Limits
Provides data sets to determine whether a trace has
exceeded allowed specified limits. You need to decide
whether the limits file is either, a limit line 1, 2, 3, or 4 by
pressing the appropriate menu key. Limits can only be
saved individually.
Frequency List Frequency list files contain your specified list of
frequencies at which measurements are to be made.
Loss
Loss files contain loss compensation data. You need to
decide whether the loss file is either a Before Table or
After Table by pressing the appropriate menu key. Files of
this type have the three letter suffix (LOS).
Screen
Saves the screen image to a file and allows you to choose
between bitmap and metafile formats. The Bitmap saves
the screen image in Graphics Interchange Format (GIF)
and the Metafile saves the screen image in Windows
Metafile (WMF) format. Also, the screen images can be
saved as reverse images where the colors are reversed.
Press Reverse Bitmap or Reverse Metafile menu key to
save a reverse image. Screen images cannot be loaded
back into the NFA.
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File Manager
Accesses menu keys that allow you to perform functions such as copying,
deleting, and renaming files.
The file manager allows you to perform house keeping functions on saved
data.
Copy
Allows you to copy a file to another file with a different
name or to a different drive (in which case the same name
is acceptable).
Copy accesses the following menu keys:
ENR
Allows you to copy ENR files.
State
Allows you to copy state files.
Trace
Allows you to copy trace files.
Limits
Allows you to copy limits files.
Frequency List
Allows you to copy frequency list files.
Loss
Allows you to copy loss compensation files.
Screen
Allows you to copy screen files.
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Delete
Allows you to delete a file from a floppy disk or the
NFA’s internal memory.
ENR
Allows you to delete ENR files.
State
Allows you to delete state files.
Trace
Allows you to delete trace files.
Limits
Allows you to delete limits files.
Frequency List
Allows you to delete frequency list files.
Loss
Allows you to delete loss compensation files.
Screen
Allows you to delete screen files.
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Rename
Allows you to rename a file. File names are limited to
eight (8) characters.
ENR
Allows you to rename ENR files.
State
Allows you to rename state files.
Trace
Allows you to rename trace files.
Limits
Allows you to rename limits files.
Frequency List
Allows you to rename frequency list files.
Loss
Allows you to rename loss compensation files.
Screen
Allows you to rename screen files.
Format
308
Formats a double-density floppy disk to 1.44 MB format.
760 KB disks are not supported.
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Save Trace
This is an action key which saves what is set-up under File. When you need
to change the parameters to be saved, press File and change them. See “File”
on page 302 for an explanation of setting up of saving files.
Preset
This key provides a convenient starting point for making most
measurements. Pressing the Preset key sets the instrument into a preset
state, the actual state depends on the Power On/Preset menu selections. See
the “Preset/Power Up Groups” on page 317, for the conditions established
by pressing Preset.
The instrument preset function performs a processor test, but does not affect
alignment data. Pressing Preset clears both the input and output buffers and
sets the status byte is set to 0. See “Preset/Power Up Groups” on page 317
for a description of the preset states.
NOTE
Switching on the NFA performs an instrument preset, and also fetches
alignment data. The last state of the NFA (before it was powered off) is
recalled when Power On (Last) is selected (under the System key).
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Print Setup
Accesses the menu keys which allow you to define a printer and select the
printer options.
This menu allows you choose the information to be printed, the layout of
that information on the printed page, and the type of printer.
Figure 6-33
Print Setup Menu Maps
Print
Pressing Print (Screen) and then the Print action key, prints out what is on
the NFA display. Pressing Print (Report) and then the Print action key,
prints out the NFA information displayed under the Show System menu
key. Show System information includes the NFA’s product number, serial
number, firmware revision, and installed options.
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Printer Type
Define Custom
Orientation
Accesses the Printer Type menu keys. When you connect your printer and
press the Print key, the NFA attempts to identify your printer. If
identification is unsuccessful, None or Custom are automatically set in the
Printer Type menu. You can select one of the following options:
None
The Printer Type is automatically set to None when you
press the Print key and there is no attached printer or an
unsupported printer is connected to your NFA.
Custom
When you press the Print key and the NFA cannot
identify your printer, Custom is automatically set in the
Printer Type menu. Setting the Printer Type menu key to
Custom allows you to define your printer using the
Define Custom menu keys.
Auto
When Auto is selected, and the Print key is pressed, the
NFA attempts to communicate with the printer and obtain
its identification. If the printer is identified, the print is
successful and no message appears on the display. If the
NFA is not able to identify the printer, the Printer Type is
automatically set to Custom and an error message asking
you to press Define Custom to set up your printer is
displayed. If the printer is not supported, the Printer Type
is automatically set to None and an error message informs
you that your printer is unsupported.
Allows you to define your printer.
Language
Allows you to define your printer as a Language(PCL3),
Deskjet type printer, or Language(PCL5), Laserjet type
printer.
Color Capable
Allows you to define the color capability of your printer.
When Color Capable(Yes) is enabled, the printer is color
capable. When Color Capable(No) is enabled, the printer
is not color capable.
Allows you to select either Portrait or Landscape printing. Landscape is
not available with a PCL3 (Deskjet) printer.
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Front Panel Key Reference
SYSTEM Keys
Color
Prints/Page
Allows you to select between color or black and white printing. This key
does not function when pressed unless the connected printer supports color.
When Color(Off) is set color printing is disabled. When Color(On) is set
color printing is enabled.
Selects the number of prints per page when orientation is set to Portrait. In
Landscape printing, Prints/Page is always set to 1.
When Prints/Page(1) is enabled, the printer ejects the page after making a
single printout. When Prints/Page(2) is enabled, the printer ejects the page
after making a second printout.
Eject Page
This causes the printer to eject the current page.
Print
Pressing the Print key initiates an output of the display data to a previously
specified graphics printer. See “Configuring a Printer with the NFA” on
page 235 of this manual for detailed information about printing.
Press the Print key to immediately print the screen to the currently-defined
printer. The screen remains frozen (no further sweeps are taken) until the
data transfer to the printer is complete. Refer to the “Print Setup” key
description in this chapter for more information about the structure and
definitions of the printer keys.
If you need to abort a print in progress, use the Esc (escape) key.
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Data Entry Keys
Data Entry Keys
Numeric Keys
These keys are used to enter numeric data. After each complete numerical
entry you need to terminate it using the units menu keys when presented to
you or the Enter key.
Back Space
Used to correct front panel numeric input value or an Alpha Editor entry.
Press the Bk Sp ⇐ key and tab back to where you need the correction over
written.
Enter
Terminates and enters into the NFA a numerical value that has been entered
from the front panel using the numeric keypad.
NOTE
For certain applications, you must use the units menu keys to terminate an
entry.
When using the File key menus, the Enter key is also used to save, load,
copy, delete, or rename a file.
Up/Down Arrow Keys
These keys are used to increment and decrement active function values, and
also to move up and down file selection lists.
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Front Panel Key Reference
Display and Menu Control Keys
Display and Menu Control Keys
Viewing Angle
Controls the optimum viewing angle of the display. The viewing angle keys
are located next to each other at the upper left-hand corner of the NFA,
bordering the display. These two keys allow you to adjust the intensity of the
display so that it can be optimally viewed from different angles.
The Viewing Angle keys automatically repeat when they are continually
pressed down.
On
This powers up the NFA.
Standby
Removes power from the NFA, except for a small portion of circuitry inside
the power supply. No internal timebase circuitry, or any other function
outside of the power supply is powered when the NFA is in Standby mode.
To remove power from the small portion of circuitry inside the power supply
which remains powered when the NFA is in Standby mode, you need to
disconnect the power cord from the rear of the NFA.
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Display and Menu Control Keys
Next Window
The Next Window key is used to switch the selection between the upper and
lower windows in dual and single graph display layout. The active window
has a green border.
NOTE
The Next Window key is also used in table and meter formats to change the
active measurement parameter. The active measurement parameter title has a
green border.
Zoom
Allows you to switch between the dual graph split-screen and full-sized
display of the active window.
The graph selected by the next window key is the one that is expanded to
create the single graph display.
NOTE
The Zoom key is only active when in graph format.
Help
This accesses a short description of any front panel key or menu key. After
pressing Help, an explanation of the next key pressed appears on the display.
The help key provides on-line help for other keys on the front panel. The
help is context sensitive so that the key’s help is specific to its current
function.
NOTE
After the help text is displayed, pressing any key, except Preset, removes
the help window. Pressing ESC allows you to remove the help window
without changing functions.
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Display and Menu Control Keys
Tab Keys
These are three Tab keys that are used to select entries in tables when editing
or viewing them. They are used in the forms to select the entry to allow you
to edit it. Also, these keys move between entry fields in the file selection
menus.
•
The up-left arrow moves to the first entry in the table.
•
The left arrow moves to the previous table entry.
•
The right arrow moves to the next table entry.
⇐Prev
Returns you to the previous menu. Repeated presses of this key move back
through previously selected menus. When a menu requiring a yes or no key
press has been accessed, the Prev key does not respond.
Esc
Deactivates the active function and clears the active function text from the
display. This ensures that no data can be accidentally entered using the RPG,
front panel keys, or numeric keypad.
Pressing Esc also aborts a print, clear input or output overloads, and clear
error messages from the status line along the bottom of the display.
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Preset/Power Up Groups
Preset/Power Up Groups
The NFA has preset and power up settings which are allocated into four
groupings. These occur on Preset/Power Up and recalling a State file.
These are as follows: •
A persistent group which remains in memory after a preset or a power
cycle and is not saved as part of a State file.
•
A “survive preset” group which remains in memory after a preset or a
power cycle and can be saved as part of a State file.
•
A No Save group which does not remain in memory after a preset or a
power cycle. It is not saved or recalled as part of a State file.
•
A State group which remains in memory after a preset or a power
cycle. It contains data which is reset by preset or a power cycle and is
stored and recalled as a State file.
Preset/Power Up — “Persistent” Group Items
The “persistent” group is stored in the NFA’s non-volatile RAM and remains
there after a preset or a power cycle. It is not stored as part of a State file,
hence is not affected when a State file is recalled. It is reset to its initial
value by Restore Sys Default, which is under the System key.
The “persistent” group items are listed in the following list: •
Automatic Filename Counter
•
Viewing Angle
•
Remote Port (Serial) or (GPIB)
•
GPIB (Noise Figure Analyzer Address)
•
GPIB (External LO Address)
•
GPIB (LO GPIB Address)
•
Serial (Data Terminal Ready)
•
Serial (Request To Send)
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Preset/Power Up Groups
•
Serial (Baud)
•
Serial (Receive Pacing)
•
Serial (Transmit Pacing)
•
Power On (Last) or (Preset)
•
Preset (Factory) or (User)
•
Time/Date (On) or (Off)
•
Date Mode (MDY) or (DMY)
•
Printer Type
•
Orientation (Portrait) or (Landscape)
•
Color (On) or (Off)
•
Prints/Page (1) or (2)
•
Language (PCL3) or (PCL5)
•
Color Capable (No) or (Yes)
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Preset/Power Up Groups
Preset/Power Up - “Survive Preset” Group Items
The “survive preset” group is stored in the NFA’s non-volatile RAM and
remains there after a preset or a power cycle. It typically contains table data
which you do not want to re-enter when the NFA is preset or power cycled.
The group can also be stored as part of a State file, hence it is refreshed
when a State file is recalled. It is reset to its initial value by Restore Sys
Default, which is under the System key.
These group items are detailed in the following list: •
Limit Lines
This also includes Type. However, it does not include Test (On) or (Off)
and Display (On) or (Off)
•
Freq List data
•
Before DUT Table and After DUT Table Loss Compensation data
•
LO Commands
The custom command strings (Power Prefix, Power Suffix, Freq Prefix,
Freq Suffix, Auxiliary)
NOTE
•
External LO, Settling Time
•
External LO, Min Freq
•
External LO, Max Freq
The ENR Table data, both Meas Table and Cal Table, is part of the “survive
preset” group. However, it is not stored as part of this group in a State file.
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Front Panel Key Reference
Preset/Power Up Groups
Unsaved Items
This data does not need to remain after a preset or a power cycle. It contains
data which is not saved or recalled from a State file. The data is reset on
power up or preset
These unsaved items are listed in the following list:
•
The current menu
•
The editing position within a table
•
The marker selection number
•
The limit line selection number
•
The file type
State Items
State saved items are stored in the NFA's non-volatile RAM and remain
there after a power cycle. These contain data which is normally reset by
preset or a power cycle. They are stored as part of a State file. It contains
all menu/remote settings except those listed in the “Unsaved Items” section.
NOTE
An NFA’s State file also stores the Calibration Data and Marker Memory
Trace Data. Hence, this data is recalled with a State file.
NOTE
Calibration Data is volatile and is lost after a power cycle. However, it is not
lost after a preset.
NOTE
Memory Trace Data is volatile and is lost after a preset or a power cycle.
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Preset/Power Up Groups
Default States
Table 6-2 shows the NFA’s system default states. Where the value is initially
not active, its activated default state is shown in parenthesis
Table 6-2
Default States
Menu Key
Default States
After DUT
Off
After DUT Fixed Value
Inactive (0.000 dB)
After Temperature
0.00 K
Alignment
On
Alignment Mode
Sweep
Annotation
On
Auto Load ENR
On
Average Mode
(Key not available on the N8972A)
Point
Averages
1
Averaging
Off
Band Pair
Inactive (Ref)
Bandwidth
4 MHz
Baud
9600
Before DUT
Off
Before DUT Fixed Value
Inactive (0.000 dB)
Before Temperature
0.00 K
Cal Table
Inactive
Center Freq (N8972A)
755.0 MHz
Center Freq (N8973A)
1.505 GHz
Center Freq (N8974A)
1.505 GHz
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Preset/Power Up Groups
Table 6-2
Default States
Menu Key
Default States
Center Freq (N8975A)
14.75 GHz
Color
Off
Combined
Off
Command Set
SCPI
Common Table
On
Continuous
Inactive (Off)
Corrected
Inactive (Off)
Define Custom
Inactive
Data->Memory
Inactive
Date Mode
MDY
Data Terminal Ready
OFF
Device Under Test
Amplifier
Display
Inactive (Off)
Display Ref
Off
ENR Mode
Table
ENR Table
Active
External LO Address
19
External LO Power Level
0.0000 dB
Find
Inactive (Off)
Fixed Freq
Inactive
Format
Graph
Freq Span (N8972A)
1.490 GHz
Freq Span (N8973A)
2.990 GHz
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Preset/Power Up Groups
Table 6-2
Default States
Menu Key
Default States
Freq Span (N8974A)
2.990 GHz
Freq Span (N8975A)
23.50 GHz
Freq. Mode
Sweep
Graticule
On
IF Frequency
Inactive (30.0 MHz)
Limit Line
1
LO Control
Off
LO Frequency
30.0 GHz
LO GPIB Address
8
LO Mode
Inactive
Marker
1
Manual State
Off
Meas Table
Inactive
Min RF Atten
0 dB
Max RF Atten
20 dB
Min μW Atten
(Key selection not on the N8972/3A)
0 dB
Max μW Atten
(Key selection not on the N8972/3A)
0 dB
Multiplier
1
Noise Figure Analyzer Address
8
Orientation
Inactive (Portrait)
Points
11
Power On
Preset
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Preset/Power Up Groups
Table 6-2
Default States
Menu Key
Default States
Preference
SNS
Preset
Factory
Print
Screen
Printer Type
Auto
Prints/Page
1
Receive Pacing
XON/XOFF
Ref. Level
4.000
Request To Send
OFF
Remote Port
GPIB
Search Type
Inactive (Max)
Sideband
LSB
Spot ENR
15.200 dB
Spot Mode
ENR
Spot Thot
9892.80 K
SNS Tcold
Inactive (On)
Start Freq (not N8975A model)
10.00 MHz
Start Freq (only N8975A model)
3.000000001 GHz
State
Off
Stop Freq (N8972A)
1.50 GHz
Stop Freq (N8973A)
3.00 GHz
Stop Freq (N8974A)
3.00 GHz
Stop Freq (N8975A)
26.50 GHz
Sweep Mode
Cont
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Preset/Power Up Groups
Table 6-2
Default States
Menu Key
Default States
System Downconverter
Off
Tcold
SNS (if connected)
Default (if SNS not connected)
Test
Inactive (Off)
Time/Date
On
Trace
Inactive (Data)
Transmit Pacing
XON/XOFF
Type
Upper
Units (Default Noise Figure)
dB
User Tcold
Off
User Tcold from SNS
Inactive
User Value
296.50K
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Front Panel Key Reference
Preset/Power Up Groups
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Chapter 6
7
Troubleshooting
This chapter includes information on how to check for a problem with your
Noise Figure Analyzer, and how to return it for service. It also includes
descriptions of all of the analyzer built-in messages.
327
Troubleshooting
What You’ll Find in This Chapter
What You’ll Find in This Chapter
This chapter includes information on how to check for a problem with your
Noise Figure Analyzer, and how to return it for service. It also includes
descriptions of all of the analyzer built-in messages.
Your analyzer is built to provide dependable service. However, if you
experience a problem, or if you desire additional information or wish to
order parts, options, or accessories, Agilent’s worldwide sales and service
organization is ready to provide the support you need.
In general, a problem can be caused by a hardware failure, a software error,
or a user error. Follow these general steps to determine the cause and to
resolve the problem.
1. Perform the quick checks listed in “Check the Basics” in this chapter. It
is possible that a quick check may eliminate your problem altogether.
2. If the problem is a hardware problem, you have several options:
•
Repair it yourself; see the “Service Options” section in this chapter.
•
Return the analyzer to Agilent Technologies for repair; if the analyzer
is still under warranty or is covered by an Agilent maintenance
contract, it is repaired under the terms of the warranty or plan (the
warranty is at the front of this manual).
If the analyzer is no longer under warranty or is not covered by an
Agilent maintenance plan, Agilent Technologies notifies you of the
cost of the repair after examining the instrument. See “Contacting
Agilent Technologies” and “How to Return Your Analyzer for
Service” for more information.
WARNING
No operator serviceable parts inside the analyzer. Refer servicing to
qualified personnel. To prevent electrical shock do not remove covers.
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Before You Call Agilent Technologies
Before You Call Agilent Technologies
Check the Basics
A problem can often be resolved by repeating the procedure you were
following when the problem occurred. Before calling Agilent Technologies
or returning the analyzer for service, please make the following checks:
? Check the line fuse.
? Is there power at the receptacle?
? Is the analyzer turned on? Make sure the fan is running, which indicates
that the power supply is on.
? If the display is dark or dim, press the upper Viewing Angle key in the
upper-left corner of the front panel. If the display is too bright, adjust the
lower Viewing Angle key in the upper-left corner of the front panel.
? If other equipment, cables, and connectors are being used with your
Noise Figure Analyzer, make sure they are connected properly and
operating correctly.
? Review the procedure for the measurement being performed when the
problem appeared. Are all the settings correct?
? If the analyzer is not functioning as expected, return the analyzer to a
known state by pressing the Preset key.
Some analyzer settings are not affected by a Preset. If you wish to
reset the analyzer configuration to the state it was in when it was
originally sent from the factory, press System, Power On/Preset,
Preset (Factory).
? Is the measurement being performed, and the results that are expected,
within the specifications and capabilities of the analyzer? Refer to the
“Technical Specifications” chapter in the Agilent NFA Series
Performance Verification and Calibration Guide for the NFA
specifications.
? In order to meet specifications, the analyzer must be aligned. Press
Chapter 7
329
Troubleshooting
Before You Call Agilent Technologies
System, Alignment and enable Alignment(On). If Alignment(Off) is
enabled the analyzer must be aligned whenever the temperature changes
more than 3° centigrade.
? Is the analyzer displaying an error message? If so, refer to “Error
Messages” in this chapter.
? If the necessary test equipment is available, perform the performance
verification tests in the Agilent NFA Series Performance Verification
and Calibration Guide. Record all results on a Performance Verification
Test Record form which follows the tests.
Read the Warranty
The warranty for your analyzer is at the front of this manual. Please read it
and become familiar with its terms.
If your analyzer is covered by a separate maintenance agreement, please be
familiar with its terms.
Service Options
Agilent Technologies offers several optional maintenance plans to service
your analyzer after the warranty has expired. Call your Agilent Technologies
sales and service office for full details.
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Before You Call Agilent Technologies
Connector Care
Cleaning connectors with alcohol shall only be done with the instruments
power cord removed, and in a well-ventilated area. Allow all residual
alcohol moisture to evaporate, and the fumes to dissipate prior to energizing
the instrument.
WARNING
If flammable cleaning materials are used, the material shall not be
stored, or left open in the area of the equipment. Adequate ventilation
shall be assured to prevent the combustion of fumes, or vapors.
For information on proper connector care and cleaning, go to the following
URL:
http://cp.literature.agilent.com/litweb/pdf/08510-90360.pdf
Contacting Agilent Technologies
For assistance, contact your nearest Agilent Technologies Sales and Service
Office. To find your local Agilent office access the following URL, or if in
the United States, call the following telephone number:
http://www.agilent.com/find/assist
1-800-829-4444 (8 am - 8 pm ET, Monday - Friday)
In any correspondence or telephone conversations, refer to your analyzer by
its product number, full serial number, and firmware revision.
Press System, More (1 of 3), Show System, and the product number, serial
number, and firmware revision information will be displayed on your
analyzer screen. A serial number label is also attached to the rear panel of
the analyzer.
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Troubleshooting
How to Return Your Analyzer for Service
How to Return Your Analyzer for Service
Detailing the Problem
If you are returning your analyzer to Agilent Technologies for servicing,
enter details of the problem and send them with the analyzer. Please be as
specific as possible about the nature of the problem. If you have recorded
any error messages that appeared on the display, or have completed a
Performance Test Record, or have any other specific data on the
performance of your analyzer, please send a copy of this information with
your analyzer.
Original Packaging
Before shipping, pack the unit in the original factory packaging materials if
they are available. If the original materials were not retained, see “Other
Packaging”.
NOTE
Ensure that the instrument handle is in the rear-facing position in order to
reduce the possibility of damage during shipping. Refer to Figure 7-1.
NOTE
Install the transportation disk into the floppy drive to reduce the possibility
of damage during shipping. If the original transportation disk is not
available, a blank floppy may be substituted.
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Troubleshooting
How to Return Your Analyzer for Service
Figure 7-1
Chapter 7
333
Troubleshooting
How to Return Your Analyzer for Service
Other Packaging
CAUTION
Analyzer damage can result from using packaging materials other than those
specified. Never use styrene pellets in any shape as packaging materials.
They do not adequately cushion the equipment or prevent it from shifting in
the carton. They cause equipment damage by generating static electricity
and by lodging in the analyzer louvers, blocking airflow.
You can repackage the instrument with commercially available materials, as
follows:
1. Attach the details of the problem to the instrument.
2. Install the transportation disk or a blank floppy disk into the disk drive.
3. If you have a front-panel cover, install it on the instrument. If you do not
have a front panel cover, make sure the instrument handle is in the
forward-facing position to protect the control panel.
4. Wrap the instrument in antistatic plastic to reduce the possibility of
damage caused by electrostatic discharge.
5. Use a strong shipping container. The carton must be both large enough
and strong enough to accommodate the analyzer. A double-walled,
corrugated cardboard carton with 159 kg (350 lb) bursting strength is
adequate. Allow at least 3 to 4 inches on all sides of the analyzer for
packing material.
6. Surround the equipment with three to four inches of packing material and
prevent the equipment from moving in the carton. If packing foam is not
available, the best alternative is S.D.-240 Air Cap™ from Sealed Air
Corporation (Hayward, California, 94545). Air Cap looks like a plastic
sheet filled with 1-1/4 inch air bubbles. Use the pink-colored Air Cap to
reduce static electricity. Wrapping the equipment several times in this
material should both protect the equipment and prevent it from moving in
the carton.
7. Seal the shipping container securely with strong nylon adhesive tape.
8. Mark the shipping container “FRAGILE, HANDLE WITH CARE” to
assure careful handling.
9. Retain copies of all shipping papers.
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NFA Battery Information
NFA Battery Information
The NFA uses a single 3V lithium battery to enable the internal memory to
retain data. The date when the battery was installed is on a label on the rear
panel of the NFA.
The minimum life expectancy of the battery is 7 years at 25°C, or 1
year at 55°C. If you experience problems with the battery or the
recommended time period for battery replacement has elapsed,
contact Agilent Technologies. Refer to “Contacting Agilent
Technologies” on page 331.
If you wish to replace the battery yourself, you can by following the service
documentation that provides all necessary test and maintenance information.
You can order the service documentation for an Agilent NFA through your
Agilent Sales and Service office.
After replacing the NFA battery, write the date of battery replacement on the
rear panel label.
WARNING
Danger of explosion if battery is incorrectly replaced. Replace only with
the same or equivalent type recommended. Discard used batteries
according to the manufacturer’s instructions.
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Troubleshooting
Error Messages
Error Messages
The analyzer can generate various messages that appear on the display
during operation. There are three types of messages.
•
Informational Messages provide information that requires no
intervention. These messages appear in the status line at the bottom of
the display, in green if you have a color display. The message remains
until you preset the analyzer, press ESC, or another message is displayed
in the status line.
•
User Error Messages appear when an attempt has been made to set a
parameter incorrectly or an operation has failed (such as saving a file).
These messages are often generated during remote operation when an
invalid programming command has been entered. These messages appear
in the status line at the bottom of the display, in yellow if you have a
color display. The message remains until you preset the analyzer, press
ESC, or another message is displayed in the status line. A summary of
the last 10 error messages may be viewed by pressing, System then
Show Errors. When generated by activity on the remote interface, the
messages are output to the remote bus. When output to the remote
interface, they are preceded by an error number. Note that the error
number is not displayed under the System, Show Errors key sequence.
•
Pop-up Messages indicate a condition that may require intervention.
They display in the middle of the display in a framed box. The message
remains until the appropriate intervention has taken place or the
condition is corrected.
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Error Messages
Informational Messages
The following messages provide information that requires no intervention.
These type of messages are in green. The information provided in brackets,
for example <filename> or <name> is a variable that represents a specific
input provided previously.
<filename> file loaded
The filename indicated has been successfully loaded.
<filename> file saved
The filename indicated has been successfully saved.
<filename> file copied
The filename indicated has been successfully copied.
<filename> file deleted
The filename indicated has been successfully deleted.
<filename1> file renamed to <filename2>
Filename1 has been successfully renamed to filename2.
Duplicate frequency entered in table,
old entry replaced
A duplicate entry was made in either the ENR table,
frequency list, limit line table or loss table. The previous
entry is replaced with the new entry.
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Troubleshooting
Error Messages
Each result type selected must differ
from all others
An attempt was made to select the same result type for
both of the two displayed result types.
Volume <name> formatted
The indicated disk has been successfully formatted.
Zoom active in graph mode only
The
key is only active when display format is set
to Graph.
Zoom inactive when showing combined
graph
The
key is not active if the display format is set to
Combined.
User cal now valid
Previously invalidated user cal is now valid due to change
of instrument parameter(s).
Invalid frequency list for measurement
mode
A frequency within the frequency list cannot be used to
make a measurement in the current mode.
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Error Messages
ENR table will be extrapolated
The measurement requires ENR values beyond the limits
of the existing ENR table.
User cal will be interpolated
For a corrected measurement, the measurement
frequencies do not coincide with the user cal frequencies.
Memory trace invalidated
A change of instrument parameter has caused the memory
trace to be invalidated (removed from screen and no
longer selectable).
Maximum number of entries in table reached
The maximum number of entries in the ENR table,
frequency list or limit line table has been reached.
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Troubleshooting
Error Messages
Error Queues
When a user-error condition occurs in the instrument as a result of SCPI
activity, it is reported to both the front-panel display-error queue and the
SCPI (remote interface) error queue. If it is a result of front-panel activity it
reports to the front panel display error queue, and may also report to the
SCPI error queue depending on the error. These two queues are viewed and
managed separately.
Error messages have a signed error number followed by some error text in
double quotes. Negative error numbers are for predefined SCPI errors, for
example error -350, “Queue overflow” which is issued if an error occurs
when the error queue is already full. Positive errors are instrument specific.
The query used to get the head of the error queue is
SYSTEM:ERROR:NEXT?. It can only retrieve one error at a time.
The special error message +0, “No error” indicates that the error queue is
empty. You can query the error queue as often as you like, when it is empty
you just keep getting +0, “No error”.
A single command or query can generate more than one error message. For
this reason it is best to drain the error queue after each command or query. If
not, you will lose track of what commands caused what errors.
Errors can occur that are not directly related to the last command issued. You
can use status information to find out if your command generated an error.
Status information can also tell you if some other type of error has occurred.
However, if the status information indicates there are different types of error
in the error queue, you cannot know which of the errors was caused by the
last command unless it is obvious from the error itself.
340
Chapter 7
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Error Messages
Table 7-1
Characteristics of the Error Queues
Characteristic
Front Panel Display
Error Queue
SCPI Remote Interface
Error Queue
Capacity (#errors)
10
30
Overflow Handling
Circular (rotating).
Drops oldest error as new error
comes in.
Linear, first-in/first-out.
Replaces newest error with:
-350,Queue overflow
Viewing Entries
Press: System, Show Errors
Use SCPI query
SYSTem:ERRor?
Clearing the Queue
Press: System, Show Errors,
Power up
Send a *CLS command
Read last item in the queue
Clear Error Queue
Error Message Format
The system-defined error numbers are chosen on an enumerated (“1 of N”)
basis. The error messages are listed in alphabetical order within each error
message type section.
In this chapter, an explanation is included with each error to further clarify
its meaning. The last error described in each class (for example, -400, -300,
-200, -100) is a “generic” error.
Error messages appear at the bottom of the display.
Chapter 7
341
Troubleshooting
Error Messages
Error Message Types
Events do not generate more than one type of error. For example, an event
that generates a query error will not generate a device-specific, execution, or
command error.
-499 to
-400: Query
Errors
These errors indicate that the instrument output queue control has detected a
problem with the message exchange protocol described in IEEE 488.2,
Chapter 6. Errors in this class set the query error bit (bit 2) in the event status
register (IEEE 488.2, section 11.5.1). These errors correspond to message
exchange protocol errors described in IEEE 488.2, 6.5. In this case:
•
Either an attempt is being made to read data from the output queue when
no output is either present or pending, or
•
data in the output queue has been lost.
-199 to
These errors indicate that the instrument parser detected an IEEE 488.2
-100: Command syntax error. Errors in this class set the command error bit (bit 5) in the event
Errors
status register (IEEE 488.2, section 11.5.1). In this case:
-399 to -300 and
201 to
799: Device-Spe
cific Errors
•
Either an IEEE 488.2 syntax error has been detected by the parser
(a control-to-device message was received that is in violation of the IEEE
488.2 standard. Possible violations include a data element which violates
device listening formats or whose type is unacceptable to the device.), or
•
an unrecognized header was received. These include incorrect
device-specific headers and incorrect or non-implemented IEEE 488.2
common commands.
These errors indicate that a device operation did not properly complete,
possibly due to an abnormal hardware or firmware condition. These codes
are also used for self-test response errors. Errors in this class set the
device-specific error bit (bit 3) in the event status register (IEEE 488.2,
section 11.5.1).
The <error_message> string for a positive error is not defined by SCPI.
342
Chapter 7
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Error Messages
-299 to -200:
These errors indicate that an error has been detected by the instrument’s
Execution Errors execution control block. The occurrence of any error in this class shall cause
the execution error bit (bit 4) in the event status register (IEEE 488.2, section
11.5.1) to be set. One of the following events has occurred:
•
A <PROGRAM DATA> element following a header was evaluated by
the device as outside of its legal input range or is otherwise inconsistent
with the device’s capabilities.
•
A valid program message could not be properly executed due to some
device condition.
Execution errors shall be reported by the device after rounding and
expression evaluation operations have taken place. Rounding a numeric data
element shall not be reported as an execution error. Events that generate
execution errors shall not generate Command errors, device-specific errors,
or Query errors.
0: No Error
0
No error
The queue is empty. Every error in the queue has been
read or the queue was purposely cleared by power-on or
*CLS.
Chapter 7
343
Troubleshooting
Error Messages
-499 to -400: Query Errors
The instrument output queue control has detected a problem with the
message exchange protocol described in IEEE 488.2, Chapter 6. Errors in
this class set the query error bit (bit 2) in the event status register (IEEE
488.2, section 11.5.1). These errors correspond to message exchange
protocol errors described in IEEE 488.2, 6.5.
In this case, either an attempt is being made to read data from the output
queue when no output is either present or pending, or data in the output
queue has been lost.
-430
Query DEADLOCKED
Indicates that a SCPI output queue has filled, preventing
further SCPI command execution, and there is no more
room left in the corresponding SCPI input queue to accept
a query to read from the output queue. The system
automatically discards output to correct the deadlock.
-400
Query Error
This is a generic query error for devices that cannot detect
more specific errors. The code indicates only that a query
error as defined in IEEE 488.2, 11.5.1.1.7 and 6.3 has
occurred.
-410
Query INTERRUPTED
Indicates that a condition causing an INTERRUPTED
query error occurred (see IEEE 488.2, 6.3.2.7). For
example, a query was followed by DAB or GET before a
response was completely sent.
-420
Query UNTERMINATED
Indicates that a condition causing an UNTERMINATED
query error occurred (see IEEE 488.2, 6.3.2.2). For
example, the device was addressed to talk and an
incomplete program message was received.
344
Chapter 7
Troubleshooting
Error Messages
-440
Query UNTERMINATED after indefinite
response
Indicates that a query was received in the same program
message after a query requesting an indefinite response
was executed (see IEEE 488.2, 6.3.7.5).
Chapter 7
345
Troubleshooting
Error Messages
-199 to -100: Command Errors
The instrument parser detected an IEEE 488.2 syntax error. Errors in this
class set the command error bit (bit 5) in the event status register (IEEE
488.2, section 11.5.1). In this case:
•
Either an IEEE 488.2 syntax error has been detected by the parser
(a control-to-device message was received that is in violation of the IEEE
488.2 standard. Possible violations include a data element which violates
device listening formats or whose type is unacceptable to the device.), or
•
an unrecognized header was received. These include incorrect
device-specific headers and incorrect or non-implemented IEEE 488.2
common commands.
-160
Block data error
This error, and also error -168, is generated when parsing
a block data element. This particular error message is
used if the device cannot detect a more specific error.
-168
Block data not allowed
A legal block data element was encountered, but not
allowed by the device at this point in the parsing.
-140
Character data error
This error, as well as errors -144 and -148, are generated
when parsing a character data element. This particular
error message is used if the device cannot detect a more
specific error.
-148
Character data not allowed
A legal character data element was encountered where
prohibited by the device.
346
Chapter 7
Troubleshooting
Error Messages
-144
Character data too long
The character data element contains more than twelve
characters (see IEEE 488.2, 7.7.1.4).
-100
Command error
This is a generic syntax error for devices that cannot
detect more specific errors. The code indicates only that a
command error as defined in IEEE 488.2, 11.5.1.1.4 has
occurred.
-110
Command header error
An error was detected in the header. This message is used
when the device cannot detect the more specific errors
described for errors -111 through -119.
-104
Data type error
The parser recognized a data element that is not allowed.
For example, numeric or string data was expected, but
block data was encountered.
-123
Exponent too large
The magnitude of an exponent was greater than 32000
(see IEEE 488.2, 7.7.2.4.1).
-170
Expression error
This error, as well as error -178, is generated when
parsing an expression data element. This particular error
message is used if the device cannot detect a more
specific error.
Chapter 7
347
Troubleshooting
Error Messages
-178
Expression data not allowed
A legal expression data was encountered, but was not
allowed by the device at this point in parsing.
-105
GET not allowed
A Group Execute Trigger was received within a program
message (see IEEE 488.2, 7.7). Correct the GPIB
controller program so that the GET does not occur within a
line of GPIB program code.
-111
Header separator error
A character which is not a legal header separator was
encountered while parsing the header.
-114
Header suffix out of range
The value of a header suffix attached to a program
mnemonic makes the header invalid.
-161
Invalid block data
A block data element was expected, but was invalid (see
IEEE 488.2, 7.7.6.2). For example, an END message was
received before the end length was satisfied.
-101
Invalid character
A syntactic command contains a character which is
invalid for that type. For example, a header containing an
ampersand, SETUP&. This error might be used in place
of error numbers -114, -121, -141 and some others.
348
Chapter 7
Troubleshooting
Error Messages
-141
Invalid character data
Either the character data element contains an invalid
character or the particular element received is not valid
for the header.
-121
Invalid character in number
An invalid character for the data type being parsed was
encountered. For example, an alpha in a decimal numeric
or a “9” in octal data.
-171
Invalid expression
The expression data element was invalid (see IEEE 488.2,
7.7.7.2). For example, unmatched parentheses or an
illegal character.
-103
Invalid separator
The parser was expecting a separator and encountered an
illegal character. For example, the semicolon was omitted
after a program message unit.
-151
Invalid string data
A string data element was expected, but was invalid (see
IEEE 488.2, 7.7.5.2). For example, an END message was
received before the terminal quote character.
-131
Invalid suffix
The suffix does not follow the syntax described in IEEE
488.2, 7.7.3.2, or the suffix is inappropriate for this
device.
Chapter 7
349
Troubleshooting
Error Messages
-109
Missing parameter
Fewer parameters were received than required for the
header. For example, the *ESE common command
requires one parameter, so receiving *ESE is not allowed.
-120
Numeric data error
This error, as well as error -128, is generated when
parsing a data element which appears to be numeric,
including non-decimal numeric types. This particular
error message is used if the device cannot detect a more
specific error.
-128
Numeric data not allowed
A legal numeric data element was received, but the device
does not accept one in this position for the header.
-108
Parameter not allowed
More parameters were received than expected for the
header. For example, the *ESE common command only
accepts one parameter, so receiving *ESE 0,1 is not
allowed.
-112
Program mnemonic too long
The header contains more than twelve characters (see
IEEE 488.2, 7.6.1.4.1).
-150
String data error
This error, as well as error -158, is generated when
parsing a string data element. This particular error
message is used if the device cannot detect a more
specific error.
350
Chapter 7
Troubleshooting
Error Messages
-158
String data not allowed
A string data element was encountered, but not allowed
by the device at this point in the parsing.
-130
Suffix error
This error, as well as errors -134 and -138, are generated
when parsing a suffix. This particular error message is
used if the device cannot detect a more specific error.
-138
Suffix not allowed
A suffix was encountered after a numeric element which
does not allow suffixes.
-134
Suffix too long
The suffix contained more than twelve characters (see
IEEE 488.2, 7.7.3.4).
-102
Syntax error
An unrecognized command or data type was encountered.
For example, a string was received when the device does
not accept strings.
-124
Too many digits
The mantissa of a decimal-numeric data element
contained more than 255 digits excluding leading zeros
(see IEEE 488.2, 7.7.2.4.1).
-113
Undefined header
The header is syntactically correct, but it is undefined for
this specific device. For example, *XYZ is not defined for
any device.
Chapter 7
351
Troubleshooting
Error Messages
-399 to -300 and 201 to 799: Device-Specific Errors
Some device operations did not properly complete, possibly due to an
abnormal hardware or firmware condition. These codes are also used for
self-test response errors. Errors in this class set the device-specific error bit
(bit 3) in the event status register (IEEE 488.2, section 11.5.1).
The <error_message> string for a positive error is not defined by SCPI.
304
Alignment failed
The alignment failed because of one of the following
reasons:
•
Gain less than 0
During alignment, the measured value of the IF
section gain was less than 0.
•
Microwave noise greater than signal
The alignment failed at the current microwave
frequency because the reading at the IF detector was
greater when only the noise floor of the instrument
was present compared to when the alignment noise
source was on.
NOTE
This error can occur if the YTF alignment has not been performed at the
current operating temperature.
NOTE
This error applies only to the N8974A and N8975A.
•
Noise greater than signal
The reading at the IF detector was greater when only
the noise floor of the instrument was present compared
to when the alignment CW signal was present.
352
Chapter 7
Troubleshooting
Error Messages
614
Bad or missing disk
The floppy is not inserted or the directory could not be
read. Insert a known good disk and try again.
219
Command not valid in this model
Indicates that the command sent from the remote interface
does not apply to this model number.
615
Corrupted file
The file that you were trying to load is corrupt.
768
Failed to load ENR data
A problem occurred when attempting to load an ENR
table.
771
Failed to load Freq list
A problem occurred when attempting to load a frequency
list.
774
Failed to load Limit Line
A problem occurred when attempting to load a limit line.
779
Failed to load Loss data
A problem occurred when attempting to load loss data.
772
Failed to store Freq list
A problem occurred when attempting to save a frequency
list.
Chapter 7
353
Troubleshooting
Error Messages
769
Failed to store ENR data
A problem occurred when attempting to save an ENR
table.
775
Failed to store Limit Line
A problem occurred when attempting to save a limit line.
780
Failed to save Loss data
A problem occurred when attempting to save loss data.
778
Failed to store Trace
A problem occurred when attempting to save a trace.
610
File access is denied
The file is protected or hidden and cannot be accessed.
604
File already exists
Attempt to save to a file that already exists. Delete or
rename the old file and try again.
607
File name error
An invalid file name has been specified. Use filenames
with a maximum of 8 characters (letters and digits only)
and use a 3 character extension. Note that lowercase and
uppercase are perceived as the same.
354
Chapter 7
Troubleshooting
Error Messages
612
File does not exist
The analyzer could not find the specified file.
754
File does not exist
The state file you were trying to recall does not exist.
500
Hardware config error
A hardware configuration error occurred due to one of the
following reasons:
•
Unknown product number
During start-up, an attempt to match the hardware
found against the NFA's product number could not be
made because the product number was unknown. This
is a fatal hardware configuration error.
•
HW ID x in slot y not required
A card with ID x was found in slot y but for this
product number is not required. This is a non-fatal
hardware configuration error.
•
HW ID x must be in slot y, not z
A card with ID x was found in slot z but was expected
to be found in slot y for this product number. This is a
fatal hardware configuration error.
•
HW ID x is missing
A card with ID x was expected for this product
number but was not found. This is a fatal hardware
configuration error.
•
Measurement not possible
An attempt was made to perform a measurement but a
previous fatal hardware configuration error has
occurred, preventing measurements.
Chapter 7
355
Troubleshooting
Error Messages
•
Option 'x' not installed
Software option 'x' must be enabled for this product
number, but was not installed. The NFA will attempt
to enable this option, requiring a power cycle. This is a
fatal hardware configuration error. (until the option is
reinstalled).
300
IF autorange failed
The IF section could not be autoranged because of one of
the following:
•
RF att. is fixed
The RF front-end attenuation is fixed.
•
RF att. limit reached
The RF front-end attenuation limit is reached.
313
IF over range req. RF re-range: Meas.
restarted
During a continuous measurement, a IF section over
range condition occurred, requiring a change of RF
front-end attenuation. To do this the measurement needs
to be restarted.
302
IF PLD error;Power detector read timed out
A read of the IF section power detector timed out.
603
Illegal MSDOS name given
An invalid file name has been specified. Use filenames
with a maximum of 8 characters (letters and digits only)
and use a 3 character extension. Note that lowercase and
uppercase are perceived as the same.
356
Chapter 7
Troubleshooting
Error Messages
770
Incorrect filename, allowable extension
ENR
Attempt to save an ENR table to a file with an incorrect
extension.
763
Incorrect filename, allowable extensions
are GIF or WMF
Attempt to save a screen image to a file with an incorrect
extension.
776
Incorrect filename, allowable extensions
LIM
Attempt to save limit line data to a file with an incorrect
extension.
781
Incorrect filename, allowable extension
LOS
An attempt was made to save loss data using an extension
other than LOS.
773
Incorrect filename, allowable extension
LST
Attempt to save frequency list data to a file with an
incorrect extension.
777
Incorrect filename, allowable extension
STA
Attempt to save the instrument state to a file with an
incorrect extension.
Chapter 7
357
Troubleshooting
Error Messages
762
Incorrect filename, allowable extension
CSV
Attempt to save a trace to a file with an incorrect
extension.
782
Incorrect SNS data format
An attempt to read SNS data failed either because the
device attached was not an SNS or because the data was
corrupt.
307
Input attenuation x dB not calibrated
Corrected measurements have been requested and the
required RF front-end attenuation setting of x dB has not
been calibrated.
751
Instrument state may be corrupt, state has
been reset to initial values
An attempt was made to load a possibly corrupt state. The
instrument state is reset to the state prior to the attempt to
load. If the state load was for a user preset, then the
instrument state is reset to the factory state.
216
Invalid baud rate
Attempt to use invalid baud rate. Refer to “Baud” on
page 293 of User’s Guide for valid rates.
308
Invalid frequency list for measurement
mode
A frequency within the frequency list cannot be used to
make a measurement in the current mode.
358
Chapter 7
Troubleshooting
Error Messages
306
Invalid input attenuation
An attempt was made to set an invalid RF front-end
attenuation limit for calibration.
701
Invalid printer response
In attempting to identify the printer an invalid response
was received. Check that you are using a supported
printer. Be sure you are using the proper cable and that it
is securely fastened.
301
LO GPIB error
An LO GPIB error occurred because of one of the
following:
•
Did not become system controller
An attempt to become system controller failed,
possibly because another controller is present on the
LO GPIB bus.
•
Need to be system controller
To perform the required action, the NFA needs to be
the system controller on the LO GPIB bus and is not
because a prior attempt to become the system
controller failed.
•
Controller collision
Another controller on the LO GPIB has attempted to
use the bus concurrently with the NFA.
•
Address bus timeout
Attempted to address bus and failed — check cabling
connections.
•
Write command timeout
Attempt to write command to device failed — check
device address is correct.
Chapter 7
359
Troubleshooting
Error Messages
•
Read response timeout
Attempt to read response from device failed - check
device address is not the same as the LO GPIB
address.
606
Media is not writable
A save was attempted to a read-only device.
605
Media is protected
A save was attempted to a write-protected device.
315
Microwave input attenuation x dB not
calibrated
Corrected measurements have been requested and the
required microwave front-end attenuation setting of x dB
has not been calibrated.
305
Mode setup error
A mode setup error occurred because of one of the
following:
•
System input frequency out of range
One or more system input frequencies are out of range.
If using a frequency list, check that all entries are valid
for current measurement mode.
•
External LO frequency out of range
One or more external LO frequencies are out of range.
Check that the LO frequency limits are set correctly
and check the entered measurement frequencies and
measurement mode.
360
Chapter 7
Troubleshooting
Error Messages
•
Stop freq must be less than fixed LO
freq
The current measurement mode requires that the stop
frequency must be less than the fixed LO frequency.
•
Start freq must be greater than start
IF freq
The current measurement mode requires that the start
RF (input to DUT) frequency must be greater than the
start IF (output from DUT) frequency.
•
LO - Stop freq must be >= min system
input freq
The current measurement mode requires that the
difference between the fixed LO frequency and the
stop RF (input to DUT) frequency must be more than
the minimum system input frequency.
•
Start freq must be greater than fixed
LO freq
The current measurement mode requires that the start
frequency must be greater than the fixed LO
frequency.
Chapter 7
361
Troubleshooting
Error Messages
•
Stop IF freq must be less than fixed LO
freq
The current measurement mode requires that the stop
IF (output from DUT) frequency must less than the
fixed LO frequency.
•
Start - LO freq must be >= min system
input freq
The current measurement mode requires that the start
RF (input to DUT) frequency must be more than the
minimum system input frequency away from the fixed
LO frequency.
•
Stop freq must be less than stop RF
freq
The current measurement mode requires that the stop
IF (output from DUT) frequency must be less than the
stop RF (input to DUT) frequency.
•
Start freq must be greater than start
RF freq
The current measurement mode requires that the start
IF (output from DUT) frequency must be greater than
the start RF (input to DUT) frequency.
•
Stop RF freq must be less than fixed LO
freq
The current measurement mode requires that the stop
RF (input to DUT) frequency must be less than the
fixed LO frequency.
•
Start freq must be greater than fixed
IF freq
The current measurement mode requires that the start
RF (input to DUT) frequency must be greater than the
fixed IF frequency.
362
Chapter 7
Troubleshooting
Error Messages
•
Start LO freq must be greater than
fixed IF freq
The current measurement mode requires that the start
LO frequency must be greater than the fixed IF
frequency.
•
Stop freq must be less than fixed IF
freq
The current measurement mode requires that the stop
RF (input to DUT) frequency must be less than the
fixed IF frequency.
•
Stop freq must be less than stop LO
freq
The current measurement mode requires that the stop
RF (input to DUT) frequency must be less than the
stop LO frequency.
310
No entries in ENR table
A measurement was attempted or a SCPI query of an
ENR table was made and there were no entries in the
relevant ENR table (Common, Meas or Cal).
309
No entries in frequency list
A measurement was attempted with List frequency mode
or a SCPI query of the frequency list table was made and
the frequency list table is empty.
311
No entries in limit line table
A measurement was attempted using a limit line table, or
a SCPI query of an limit line table was made and there
were no entries in the relevant limit line table.
Chapter 7
363
Troubleshooting
Error Messages
314
No entries in loss table
A measurement was attempted or a SCPI query of a loss
table was made and there were no entries in the relevant
loss table (either Before or After table).
700
No printer response
An attempt to identify the printer failed.
704
Printer interface error
An error occurred while trying to print. Make sure the
printer is turned on and properly connected.
705
Printer type is none
The current printer type is set to None, so no print
operations are possible. Change the type in the Print
Setup menu and try again.
-350
Queue Overflow
There is no room in the error queue and an error occurred
but was not recorded.
312
RF re-range required: Meas. restarted
During a continuous measurement, a change of RF
front-end attenuation was required. To do this the
measurement needs to be restarted.
364
Chapter 7
Troubleshooting
Error Messages
217
RS-232 Interface Error
An error occurred on the serial interface due to one of the
following reasons:
•
Input data overrun
An error occurred on the serial interface.
•
Input data parity
An error occurred on the serial interface.
•
Input data framing
An error occurred on the serial interface.
•
Output data timeout
An error occurred on the serial interface
•
Command input timeout
An error occurred on the serial interface.
-330
Self-Test Failed
A self-test error occurred due to one of the following
reasons:
Chapter 7
•
IF test [x][y] failure
•
RF test [x] failure
•
RF gain (x) out of range
•
IF gain out of range
•
RF cal x out of range amp[y]
•
RF amp[x] floor too high
•
Tuner EEPROM cal value out of range
•
IF filter offset x out of range
365
Troubleshooting
Error Messages
501
SNS read failure
An attempt to read from the SNS failed. This could be due
to SNS cable problems such as poor connection or
disconnection while reading.
502
SNS write failure
An attempt to write to the SNS failed. This could be due
to SNS cable problems such as poor connection or
disconnection while writing.
316
Thot must be greater than Tcold
A spot Thot temperature has been specified which is not
greater than Tcold temperature.
766
Unable to format drive
A problem occurred when attempting to format a drive.
765
Unable to load file
A problem occurred when attempting to load a file.
759
Unable to load state file into instrument
with older firmware date
A saved state file from a newer firmware revision was
attempted to be loaded into an older instrument.
752
Unable to load state from file
An attempt to load a state from the File Manager or
through MMEM:LOAD:STAT failed. Preceding error
messages may indicate the cause of failure.
366
Chapter 7
Troubleshooting
Error Messages
755
Unable to load state from register
An attempt to load a state from a register using the *RCL
command failed. Preceding error messages may indicate
the cause of failure.
757
Unable to load user state, factory preset
was done
An attempt to perform a User Preset failed, so the
Factory Preset values were used. Save a valid state into
User Preset and try again.
760
Unable to query state from the remote
A problem occurred while trying to query the instrument
state as part of a *LRN command.
764
Unable to save file
A failure occurred while saving a file; the file was not
saved.
753
Unable to save state to file
An attempt to save a state from the File Manager or
through MMEM:STOR:STAT failed. Preceding error
messages may indicate the cause of failure.
756
Unable to save state to register
An attempt to save a state to a register using the *SAV
command failed. Preceding error messages may indicate
the cause of failure.
Chapter 7
367
Troubleshooting
Error Messages
758
Unable to save user state
An attempt to save the User Preset state failed.
761
Unable to set state from the remote
A problem occurred while trying to set the instrument
state as part of a SYST:SET command.
703
Unknown printer
In attempting to identify the printer, a valid response was
received but the printer is not known to the analyzer. Use
the Custom printer menu under Print Setup to configure
the printer.
702
Unsupported printer
A printer which is recognized, but known to be
unsupported was identified. This printer cannot be used
with the analyzer. For example, a printer only supported
by Microsoft Windows generates this error.
368
Chapter 7
Troubleshooting
Error Messages
303
User cal invalidated
The existing user cal has been invalidated because of one
of the following reasons:
•
Meas mode changed
The measurement mode has been changed from that
used for user cal.
•
Freq outside cal range
The current measurement frequencies lie partially or
wholly outside the range of frequencies used for user
cal.
•
Fixed IF changed
The fixed IF frequency has been changed from that
used for user cal.
•
Fixed LO changed
The fixed LO frequency has been changed from that
used for user cal.
•
Sideband changed
The sideband has been changed from that used for user
cal.
Chapter 7
369
Troubleshooting
Error Messages
660
YTF align error
The alignment failed because of one of the following
reasons:
•
Peak / floor too small
During a YTF alignment the level of a peak above the
noise floor was too small. If this error occurs then the
quality of the YTF alignment is questionable.
•
Image / floor too small
During a YTF alignment the level of an image
response above the noise floor was too small. If this
error occurs then the quality of the YTF alignment is
questionable.
370
Chapter 7
Troubleshooting
Error Messages
-299 to -200:
Execution Errors
-222
Data out of range
A parameter of a command or query was outside the
defined range for that command or query.
-224
Illegal parameter value
An unexpected value was entered. (for example, a value
other then the available options)
-225
Out of memory
The analyzer has insufficient memory to perform the
requested operation.
-221
Settings conflict
A legal program data element was parsed but could not be
executed due to the current device state.
-223
Too much data
A block, expression or string parameter of a command or
query contained more data than the analyzer could handle
due to memory constraints.
-213
Init ignored
Indicates that a request for a measurement initiation was
ignored as another measurement was in progress.
NOTE
The front panel Restart key does not generate this error, only the remote
command INIT:IMM.
Chapter 7
371
Troubleshooting
Error Messages
-230
Data corrupt or stale
Possibly invalid data; new reading started but not
completed since last access.
372
Chapter 7
Index
Numerics
Symbols
(Local) key, 289
Numerics
10 MHz ref connection, 157
10 MHz ref in, 26
10 MHz ref out, 26
3.0 GHz switch, 18
3.5 mm connector, 18
A
active function, 28
active marker, 93, 266
address GPIB, 219
After DUT Table menu key, 276
Agilent Technologies, contacting,
331
Align YTF (saving) menu key, 297
Align YTF menu key, 297
alignment, 228
Alignment (internal) menu key, 296
Alignmnt Mode (internal) menu key,
297
alpha editor, 46
annotation, 30, 89
Annotation menu key, 263
arrow keys, 23
Auto menu key, 311
Autoscale menu key, 258
AUX IN (TTL), 26
AUX OUT (TTL), 26
Auxiliary menu key, 295
Average Mode menu key, 246
Averages menu key, 246
Averaging, 71
Averaging menu key, 245
Averaging/Bandwidth key, 245
B
Back Space keys, 313
Index
Band Pair (State) menu key, 268
band pair marker, 96
Band Pair menu key, 268
Bandwidth, 71
Bandwidth menu key, 246
battery, 335
Baud menu key, 293
Before DUT Table menu key, 275
Bitmap menu key, 305
C
Cal Table menu key, 254
Calibrate key, 247
calibration, 74
input attenuation range, 78
performing, 76
reasons to, 74
using interpolated results, 75
Center Freq menu key, 242
checking the basics, 329
Clear Error Queue, 297
clock
setup, 300
Color Capable Yes No, 311
Color menu key, 312
Color On Off, 312
Combined menu key, 262
command error messages, 346
Command Set menu key, 294
Common Table menu key, 252
Configuring
Extended Frequency
Measurements, 137
configuring
alignment, 228
alignment mode, 228
alignment YTF, 229
external LO, 223
GPIB address, 219
loss compensation
fixed value, 119
table value, 122
serial port, 221
temperature loss, 129
connect
10 MHz timebase, 157
Connecting
NFA for extended measurements,
157
connector
10 MHz ref in, 26
10 MHz ref out, 26
50 ohm input, 23
APC 3.5 mm, 23
AUX IN (TTL), 26
AUX OUT (TTL), 26
external keyboard, 23
GPIB, 26
LO GBIB, 26
noise source output, 23
parallel port, 26
probe power, 23
RS-232 port, 26
service, 26
SNS, 24
Type-N, 23
VGA, 26
Continuous menu key, 270
CONTROL functions, 22
copy files, 43
Copy menu key, 306
Corr key, 281
Corrected menu key, 281
creating
frequency list, 67
limit line, 115
custom command, 223
Custom menu key, 311
D
Data Entry Keys, 313
data invalid indicator, 31
Data Terminal Ready menu key, 292
Data->Memory menu key, 263
373
Index
date
setting, 234
date display, 300
Datemode MDY DMY, 300
Default States, 321
Define Custom menu key, 311
delete files, 44
Delete menu key, 307
Delta (State) menu key, 267
delta marker, 95
Device Under Test menu key, 248
device-specific error messages
201 to 799, 352
-399 to -300, 352
Diagnostics menu key, 301
disk format, 39
display
annotation, 89
combining graph, 86
display reference, 92
format, 81
full screen, 83
graticule, 88
markers, 93
memory trace, 87
result type, 84
scaling, 90
single graph, 85
Display and Menu Control Keys, 314
display annotation, 30
DISPLAY functions, 22
Display menu key, 279
Display Ref menu key, 260
Displaying
Error History, 230
displaying
hardware information, 230
system information, 230
displaying results, 81
Downconverter description, 165
Downconverting
Fixed IF Variable LO, 143
Variable IF Fixed LO, 144
374
E
Edit Table menu key, 253
editor
limit line, 115
Editor (limit line) menu key, 278
Eject Page menu key, 312
ENR, 51
ENR key, 252
ENR Mode menu key, 252
ENR spot value, 58
ENR table calibrate, 52
ENR table common, 51
ENR table measurement, 52
ENR Table menu key, 253
ENR table normal data entry, 52
Enter key, 313
entering normal ENR data, 52
error messages
-199 to -100, 346
201 to 799, 352
-399 to -300, 352
-499 to -400, 344
command, 346
device-specific (201 to 799), 352
device-specific (-399 to -300), 352
empty error queue, 343
format, 341
query, 344
types, 342
Error queue
clearing, 230
displaying, 230
error queue, 230
error queues
empty message, 343
front panel, 341
SCPI remote interface, 341
Esc key, 21, 316
Escape, 316
Example
Down-Convertor Measurements,
172
System Downconverter
Measurements, 194
example
making a basic amplifier
measurement, 104
making a fixed frequency
measurement, 34
Excess Noise Ratio, 51
external keyboard connector, 23
external LO
configuring, 223
custom commands, 223
min and max freq, 226
multiplier freq, 227
settling time, 226
External LO Address menu key, 291
External LO menu key, 294
External LO Power Level menu key,
250
F
file copying, 43
file deleting, 44
file format S2P, 127
File key, 302
file loading, 42
File Manager menu key, 306
file menu functions
copy, 43
delete, 44
format, 39
load, 42
rename, 42
save, 41
file renaming, 42
file saving, 41
Fill Table From SNS menu key, 254
filter requirements, 165
Find menu key, 270
fixed ENR, 58
Fixed Freq menu key, 242
Fixed value loss compensation, 119
Index
Index
floppy disk format, 39
format, 81
format a disk, 39
Format key, 262
Format menu key, 262
Freq List menu key, 243
freq mode
fixed, 65
list, 65
sweep, 65
Freq Mode menu key, 242
Freq Prefix menu key, 295
Freq Span menu key, 242
Freq Suffix menu key, 295
frequency list
creating, 67
using swept points, 69
using the fill, 69
Frequency Restrictions, 207
Frequency/Points key, 240
Frequency-Converting description,
159
front panel
error queue characteristics, 341
front panel input connector,precision
3.5 mm connector, 18
front panel overview, 21
Front Panel Test, 301
full screen, 83
Full Screen key, 280
full span, 65
Full Span menu key, 243
fuse, 26
G
Gain menu key, 265
GPIB address, 219
setting, 219
GPIB annunciators, 31
GPIB menu key, 291
graticule, 88
Graticule menu key, 263
H
hardware information
displaying, 230
hardware problems, 328
Help key, 315
help key, 24
how to return your analyzer for
service, 332
I
ID menu key, 254
IF Frequency menu key, 250
IF Input Over Range Condition, 103
IF Under Range Conditions, 103
IFO, 103
IFU, 103
indicator IFO, 103
indicator IFU, 103
indicator RFO, 102, 103
indicator RFU, 102, 103
input
power, 25
INPUT 50 OHM, 23
input attenuation range microwave,
79
Input Attenuation Range RF, 78
Input Cal menu key, 282
input calibration, 78
instrument preset, 231, 309
intensity
viewing angle, 21
internal alignment
configuring, 228
interpolated corrected state, 74
invalid result, 102
K
key
Averaging/Bandwidth, 245
Back Space, 313
Calibrate, 247
Corr, 281
Index
ENR, 252
Enter, 313
Esc, 316
File, 302
Format, 262
Frequency/Points, 240
Full Screen, 280
Help, 315
Limit Lines, 277
Local, 289
Loss Comp, 271
Marker, 266
Meas Mode, 248
Mode Setup, 250
Next Window, 315
Numeric, 313
On, 314
Preset, 309
Prev, 316
Print, 312
Print Setup, 310
Restart, 288
Result, 264
Save Trace, 309
Scale, 258
Standby, 314
Sweep, 284
System, 289
System (Local), 289
Tab, 316
Up/Down Arrow, 313
viewing angle, 314
Zoom, 315
key group
control, 271
display, 258
measure, 240
system, 289
key overview, 28
key presses
Fixed IF Variable LO
(Downconvert), 143
375
Index
Fixed IF Variable LO (System
Downconvert), 149, 150
Fixed IF Variable LO (Upconvert),
146
Variable IF Fixed LO
(Downconvert), 144
Variable IF Fixed LO (Upconvert),
147
L
Language PCL3 PCL5, 311
limit line
editor, 115
limit line 1, 113
limit line 2, 113
limit line 3, 113
limit line 4, 113
Limit Line menu key, 277
Limit Lines All Off menu key, 279
Limit Lines key, 277
limit lines use, 113
Limits (file) menu key, 303
lithium battery, 335
LO Commands menu key, 294
LO Control menu key, 250
LO Frequency menu key, 250
LO frequency multiplier, 227
LO frequency setting, 226
LO GBIB, 26
LO GPIB Address menu key, 291
LO Mode menu key, 248
load files, 42
Load menu key, 302
Loading S2P files, 127
Loss Comp key, 271
loss compensation configuring, 119,
122
loss compensation use, 119
Lower Limit menu key, 260
M
MAIN GPIB, 26
376
Manual Meas menu key, 284
manual measurement procedure, 133
manual measurements, 131
Marker 1, 93
Marker 2, 93
Marker 3, 93
Marker 4, 93
Marker key, 266
Marker menu key, 267
marker state
delta, 95, 96
memory, 99
markers, 93
band pair, 96
memory traces, 99
searching, 100
selecting, 93
states, 95
Markers All Off menu key, 270
marking memory traces, 99
Max Freq menu key, 296
maximum frequency, 226
Meas Mode key, 248
Meas Table menu key, 254
MEASURE functions, 22
measurement
fixed, 34
sweep, 104
Measurement Modes
Frequency-Downconverting, 142
Frequency-Upconverting, 145
N8970B comparison, 151
Overview, 139
System Downconvertor, 148
mechanical 3.0 GHz switch, 18
memory marker, 99
menu keys, 22
Metafile menu key, 305
methods of normal ENR data entry,
52
microwave front panel connector, 18
microwave input attenuation range,
79
Min Freq menu key, 296
minimum LO frequency, 226
mode
fixed frequency, 70
Mode Setup key, 250
monitor output, 26
multiplier LO frequency, 227
Multiplier menu key, 296
N
N8970B Mode Comparison, 151
N8970B Modes, 151
next window, 24
Next Window key, 315
NFA features, 18, 19
Noise Figure Analyzer Address menu
key, 291
Noise Figure menu key, 265
noise source
model number, 54
serial number, 54
noise source normal, 51
noise source output, 23
noise source smart, 51
None menu key, 311
Normal (State) menu key, 267
normal noise source, 51
Numeric Keys, 313
numeric keys, 23
O
Off (State) menu key, 267
On key, 314
Option 1D5, 19
options, 19
Orientation, 311
Orientation menu key, 311
Overview
Extended Frequency
Measurements, 137
Measurement Modes, 139
Index
Index
P
packaging, 332
parallel connector, 26
Pcold menu key, 265
persistent, 317
Phot menu key, 265
Points menu key, 243
power input, 25
Power On(Last) menu key, 298
Power On(Preset) menu key, 298
Power On/Preset menu key, 298
Power Prefix menu key, 295
Power Suffix menu key, 295
Power-On conditions
defining, 232
Preset, 231
defining conditions, 232
preset
system defaults, 233
Preset (Factory) menu key, 299
Preset (User) menu key, 299
Preset key, 22, 309
Presetting, 231
pressing full span, 65
Prev, 316
Print key, 312
Print menu key, 310
Print Screen Report, 310
Print Setup key, 310
printer output, 26
Printer Type menu key, 311
printing, 312
printing, parallel
deskjet, 235
epson, 235
laserjet, 235
paintjet, 235
thinkjet, 235
Prints/Page 1 2, 312
Prints/Page menu key, 312
probe power connector, 23
product family, 18
product options, 19
Index
Q
queries
error messages, 344
R
real-time clock
set date, 300
set time, 300
rear panel features, 25
rear panel overview, 25
Receive Pacing menu key, 293
ref level, 92
Ref. Level menu key, 260
remote
interface (SCPI) error queue, 341
Remote Port menu key, 290
rename files, 42
Rename menu key, 308
Request To Send menu key, 292
Restart key, 288
Restore System Defaults menu key,
299
Restricted Terms, 207
result invalid, 102
Result key, 264
result type, 84
results displaying, 81
returning your analyzer for service,
332
Reverse Bitmap menu key, 305
Reverse Metafile menu key, 305
RF Input Attenuation Range, 78
RF Input Over Range Condition, 102,
103
RF Under Range Conditions, 102,
103
RFO, 102, 103
RFU, 102, 103
RPG, 23
RS-232 connector, 26
S
S1 file format, 127
S2 file format, 127
S2P file format, 127
save files, 41
Save menu key, 304
Save Trace key, 309
Save User Preset menu key, 299
save YTF alignment, 297
saving
ENR table data, 58
Scale key, 258
Scale/Div menu key, 260
scaling, 90
SCPI remote interface error queue
characteristics, 341
Search menu key, 269
Search Type menu key, 269
searching markers, 100
selecting a fixed freq, 70
selecting a freq list, 67
selecting a freq sweep, 65
selecting averaging, 72
selecting bandwidth, 71
selecting markers, 93
serial data output, 26
Serial menu key, 292
Serial Number menu key, 253
serial port
setting up, 221
Service menu key, 301
service options, 330
Set Date menu key, 300
Set Time menu key, 300
Setting
Maximum LO Frequencies, 155
Minimum LO Frequencies, 155
Multiplier, 156
Settling Time, 156
setting
external LO, 223
GPIB address, 219
serial port, 221
377
Index
setting date, 234
setting Tcold, 62
setting the microwave input
attenuation, 80
setting Thot, 59
setting time, 234
Setting up
NFA for extended measurments,
157
setting up limit lines, 113
settling time, 226
Settling Time menu key, 296
Setup (loss comp) menu key, 272
Show Errors menu key, 297
Show Hdwr menu key, 298
Show System menu key, 297
Sideband menu key, 250
single sideband (SSB), 164
Smart Noise Source (SNS), 51
SNS connector, 24
SNS Setup menu key, 257
SNS Tcold menu key, 256
spot ENR, 58
Spot ENR menu key, 255
spot Thot, 59
Standby key, 314
Start Freq menu key, 242
State (file) menu key, 303
State menu key, 267
Stop Freq menu key, 242
survive preset, 319
Sweep key, 284
Sweep Mode menu key, 284
switch reliability, 18
System (Local) key, 289
System Downconverter description,
184
System Downconvertor
Fixed IF Variable LO, 149, 150
System Downconvertor menu key,
248
SYSTEM functions, 22
system information
378
displaying, 230
System key, 289
viewing angle, 21
Viewing Angle key, 314
T
Tab Keys, 23, 316
table value loss compensation, 122
tcold data changing, 62, 63, 64
Tcold menu key, 256
Tcold setting, 62
Teffective menu key, 265
temperature correction, 62, 63, 64
temperature loss configuring, 129
Test (limit line) menu key, 278
Thot spot value, 59
time
setting, 234
Time/Date menu key, 300
Time/Date On Off, 300
torque value, 18
Trace menu key, 263, 268
Transmit Pacing menu key, 293
turning off markers, 270
Type (limit line) menu key, 277
W
warm-up time, 24
warranty, 330
working with tables, 45
Y
Y Factor menu key, 265
YTF alignment, 229
Z
zoom, 24
Zoom key, 315
U
uncorrected state, 74
Units menu key, 259
Up/Down Arrow Keys, 313
Upconverter description, 165
Upconverting
Fixed IF Variable LO, 146
Variable IF Fixed LO, 147
Upper Limit menu key, 260
User Tcold From SNS menu key, 256
User Tcold menu key, 256
User Value menu key, 256
using alpha editor, 46
using tables, 45
V
VGA connector, 26
video connector, 26
Index
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