Spectrum Analyzer Mode Measurement Guide

196 Pages·2010·6.26 MB·English

by  Agilent Technologies

Agilent X-Series
Signal Analyzer
This manual provides documentation for
the following X-Series Analyzers:

P XA Signal Analyzer N9030A
M XA Signal Analyzer N9020A
EXA Signal Analyzer N9010A
CXA Signal Analyzer N9000A
Spectrum Analyzer Mode
Measurement Guide
Notices
© Agilent Technologies, Inc. 2008-2009 Manual Part Number licensed as “Commercial computer soft-
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Warranty
This Agilent technologies instrument product is warranted against defects in material and workmanship for a
period of one year from the date of shipment. During the warranty period, Agilent Technologies will, at its
option, either repair or replace products that prove to be defective.
For warranty service or repair, this product must be returned to a service facility designated by Agilent
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Where to Find the Latest Information
Documentation is updated periodically. For the latest information about this analyzer, including firmware
upgrades, application information, and product information, see the following URLs:
http://www.agilent.com/find/pxa
http://www.agilent.com/find/mxa
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http://www.agilent.com/find/cxa
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Contents
1 Getting Started with the Spectrum Analyzer Measurement Application
Making a Basic Measurement 10
Using the Front Panel 10
Presetting the Signal Analyzer 11
Viewing a Signal 12
Recommended Test Equipment 15
Accessories Available 16
50 Ohm Load 16
50 Ohm/75 Ohm Minimum Loss Pad 16
75 Ohm Matching Transformer 16
AC Probe 16
AC Probe (Low Frequency) 16
Broadband Preamplifiers and Power Amplifiers 17
GPIB Cable 17
USB/GPIB Cable 17
RF and Transient Limiters 17
Power Splitters 18
Static Safety Accessories 18
2 Measuring Multiple Signals
Comparing Signals on the Same Screen Using Marker Delta 20
Comparing Signals not on the Same Screen Using Marker Delta 23
Resolving Signals of Equal Amplitude 26
Resolving Small Signals Hidden by Large Signals 31
Decreasing the Frequency Span Around the Signal 35
Easily Measure Varying Levels of Modulated Power Compared to a Reference 37
3 Measuring a Low−Level Signal
Reducing Input Attenuation 42
Decreasing the Resolution Bandwidth 45
Using the Average Detector and Increased Sweep Time 48
Trace Averaging 50
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Contents
4 Improving Frequency Resolution and Accuracy
Using a Frequency Counter to Improve Frequency Resolution and Accuracy 54
5 Tracking Drifting Signals
Measuring a Source Frequency Drift 56
Tracking a Signal 59
6 Making Distortion Measurements
Identifying Analyzer Generated Distortion 62
Third-Order Intermodulation Distortion 65
7 Measuring Noise
Measuring Signal-to-Noise 70
Measuring Noise Using the Noise Marker 72
Measuring Noise-Like Signals Using Band/Interval Density Markers 76
Measuring Noise-Like Signals Using the Channel Power Measurement 79
Measuring Signal-to-Noise of a Modulated Carrier 81
Improving Phase Noise Measurements by Subtracting Signal Analyzer Noise 86
8 Making Time-Gated Measurements
Generating a Pulsed-RF FM Signal 92
Signal source setup 92
Analyzer Setup 93
Digitizing oscilloscope setup 95
Connecting the Instruments to Make Time-Gated Measurements 97
Gated LO Measurement 98
Gated Video Measurement 102
Gated FFT Measurement 106
9 Measuring Digital Communications Signals
Channel Power Measurements 110
Occupied Bandwidth Measurements 112
Troubleshooting Hints 113
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Contents
Making Adjacent Channel Power (ACP) Measurements 114
Making Statistical Power Measurements (CCDF) 119
Making Burst Power Measurements 124
Spurious Emissions Measurements 130
Troubleshooting Hints 132
Spectrum Emission Mask Measurements 133
Troubleshooting Hints 134
10 Demodulating AM Signals
Measuring the Modulation Rate of an AM Signal 138
Measuring the Modulation Index of an AM Signal 142
11 IQ Analyzer Measurement
Capturing wideband signals for further analysis 146
Complex Spectrum Measurement 147
IQ Waveform (Time Domain) Measurement 149
12 Using Option BBA Baseband I/Q Inputs
Baseband I/Q Measurements Available for X-Series Signal Analyzers 154
Baseband I/Q Measurement Overview 155
13 Concepts
Resolving Closely Spaced Signals 158
Resolving Signals of Equal Amplitude 158
Resolving Small Signals Hidden by Large Signals 158
Trigger Concepts 160
Selecting a Trigger 160
Time Gating Concepts 164
Introduction: Using Time Gating on a Simplified Digital Radio Signal 164
How Time Gating Works 166
Measuring a Complex/Unknown Signal 172
“Quick Rules” for Making Time-Gated Measurements 177
Using the Edge Mode or Level Mode for Triggering 180
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Contents
Noise Measurements Using Time Gating 181
AM and FM Demodulation Concepts 182
Demodulating an AM Signal Using the Analyzer as a Fixed Tuned Receiver
(Time-Domain) 182
Demodulating an FM Signal Using the Analyzer as a Fixed Tuned Receiver
(Time-Domain) 182
IQ Analysis Concepts 183
Purpose 183
Complex Spectrum Measurement 183
IQ Waveform Measurement 183
Spurious Emissions Measurement Concepts 185
Purpose 185
Measurement Method 185
Spectrum Emission Mask Measurement Concepts 186
Purpose 186
Measurement Method 186
Occupied Bandwidth Measurement Concepts 187
Purpose 187
Measurement Method 187
Baseband I/Q Inputs (Option BBA) Measurement Concepts 188
What are Baseband I/Q Inputs? 188
What are Baseband I/Q Signals? 188
Why Make Measurements at Baseband? 189
Selecting Input Probes for Baseband Measurements 190
Baseband I/Q Measurement Views 191
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Getting Started with the Spectrum Analyzer Measurement Application
1 Getting Started with the
Spectrum Analyzer
Measurement Application
This chapter provides some basic information about using the Spectrum Analyzer and
IQ Analyzer Measurement Application Modes. It includes topics on:
• “Making a Basic Measurement” on page 10
• “Recommended Test Equipment” on page 15
• “Accessories Available” on page 16
Technical
Documentation
Summary:
Your Signal Analysis measurement platform:
Getting Started Turn on process, Windows XP use/configuration, Front and rear panel
Specifications Specifications for all available Measurement Applications and optional
hardware (for example, Spectrum Analyzer and W-CDMA)
Functional Testing Quick checks to verify overall instrument operation.
Instrument Messages Descriptions of displayed messages of Information, Warnings and Errors
Measurement Application specific documentation:
(for example, Spectrum Analyzer Measurement Application or W-CDMA Measurement Application)
Measurement Guide Examples of measurements made using the front panel keys or over a remote
interface.
User’s/Programmer’s Descriptions of front panel key functionality and the corresponding SCPI
Reference commands. May also include some concept information.
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Getting Started with the Spectrum Analyzer Measurement Application
Making a Basic Measurement
Making a Basic Measurement
Refer to the description of the instrument front and rear panels to improve your
understanding of the Agilent Signal Analyzer measurement platform. This knowledge
will help you with the following measurement example.
This section includes:
• “Using the Front Panel” on page 10
• “Presetting the Signal Analyzer” on page 11
• “Viewing a Signal” on page 12
CAUTION Make sure that the total power of all signals at the analyzer input does not exceed
+30 dBm (1 watt).
Using the Front Panel
Entering Data
When setting measurement parameters, there are several ways to enter or modify the
value of the active function:
Knob Increments or decrements the current value.
Arrow Keys Increments or decrements the current value.
Numeric Keypad Enters a specific value. Then press the desired terminator (either a
unit softkey, or the Enter key).
Unit Softkeys Terminate a value that requires a unit-of-measurement.
Enter Key Terminates an entry when either no unit of measure is needed, or
you want to use the default unit.
Using Menu Keys
Menu Keys (which appear along the right side of the display) provide access to many
analyzer functions. Here are examples of menu key types:
Toggle Allows you to activate/deactivate states.
Example: Toggles the selection (underlined choice) each time you
press the key.
Submenu Displays a new menu of softkeys.
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