Agilent E4402B User’s, Programming, and Measurement Guide

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User’s, Programming, and Measurement Guide

Agilent Technologies

ESA-E Series Spectrum Analyzers

Modulation Analysis Measurement Personality

This guide documents firmware revision A.08.xx

This manual provides documentation for the following instruments:

Agilent ESA-E Series

E4402B (9 kHz - 3.0 GHz) E4404B (9 kHz - 6.7 GHz) E4405B (9 kHz - 13.2 GHz) E4407B (9 kHz - 26.5 GHz)

Manufacturing Part Number: E4402-90071

Supersedes E4402-90037

Printed in USA

February 2002

Notice

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.

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 that 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.

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.

Safety Information

The following safety notes are used throughout this manual. Familiarize yourself with these notes 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.

WARNING This is a Safety Class 1 Product (provided with a protective earth ground

incorporated in the power cord). The mains plug shall be inserted only 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 No operator serviceable parts inside. Refer servicing to qualified personnel.

To prevent electrical shock do not remove covers.

CAUTION Always use the three-prong AC power cord supplied with this product. Failure to

ensure adequate grounding may cause product damage.

Contents

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1. Using This Document

BookOrganization........................................................... 16

2. Understanding Modulation Analysis

DigitalCommunicationSystemsStandardsOverview .............................. 20

ThecdmaOne(IS-95)CommunicationSystem................................... 20

TheW-CDMACommunicationSystem......................................... 20

TheCDMA2000CommunicationSystem ....................................... 20

W-CDMAandcdma2000Advantages .......................................... 20

cdmaOneStandards........................................................ 22

TheNADCCommunicationsSystem........................................... 25

TheGSMStandards........................................................ 26

TheEDGEStandard........................................................ 30

ThePDCStandard ......................................................... 32

TheTETRAStandard....................................................... 32

WhattheModulationAnalysisMeasurementPersonalityDoes....................... 33

OtherSourcesofMeasurementInformation ...................................... 36

3. Getting Started

InstrumentOverview......................................................... 38

Front-PanelFeatures ....................................................... 38

Rear-PanelFeatures........................................................ 39

OptionsRequired............................................................ 41

Installing Optional Measurement Personalities . . . ................................ 43

ActiveLicenseKey ......................................................... 43

Installing the Licensing Key ................................................. 43

UsingtheInstallKey ....................................................... 44

InstallerScreenandMenu................................................... 47

AgilentESASpectrumAnalyzersUpdate....................................... 48

4. Setting Up the Modulation Analysis Mode

PreparingtoMakeMeasurements .............................................. 50

InitialSettings ............................................................ 50

HowtoMakeanEVM(ErrorVectorMagnitude)Measurement..................... 51

HowtoSaveMeasurementResults............................................ 52

5. Making Modulation Analysis Measurements

WhatYouWillFindinThisChapter.............................................54

TheModulationAnalysisPersonality............................................ 55

Purpose ..................................................................55

MeasurementMethodforaCDMASystem...................................... 56

MakingaWidebandCDMAMeasurement........................................ 57

InterpretingMeasurementResults.............................................. 64

BasebandFilteringErrors................................................... 64

I/QGainImbalance......................................................... 69

I/QQuadrature(Skew)Error................................................. 71

SymbolRateError ......................................................... 74

I/QDCOffsetError......................................................... 77

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In-ChannelPhaseModulatingInterference......................................78

In-ChannelAmplitudeModulationInterference ..................................81

In-ChannelSpuriousSignalInterference........................................85

MeasuringaCustomQPSKFormatSignal........................................87

OtherCustomizedChangesYouCanMake .......................................88

ProblemsObtainingaMeasurement.............................................89

InMonitorSpectrummode,thesignalismissing,ordoesnotlookcorrect.............89

When using the GSM or EDGE standards, the spectrum looks valid, but all EVM

measurementsareinvalid ...................................................89

AnNADC,TETRA,orPDCsignallooksincorrect ................................90

A“WidebandCalRequired”errormessageappears ...............................90

TheresultsshowalargeEVM ................................................91

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6. Menu Maps

WhatYouWillFindinThisChapter.............................................94

Menus......................................................................95

AmplitudeMenu ...........................................................95

Det/DemodMenus ..........................................................96

DisplayMenus .............................................................97

Frequency/ChannelMenu....................................................98

InstallerMenus ............................................................99

MeasureMenu ............................................................100

MeasurementSetupMenus .................................................101

ModeMenu ..............................................................103

ModeSetupMenus ........................................................104

Span(XScale)Menu .......................................................105

TriggerMenu .............................................................106

ViewandTraceMenu ......................................................107

7. Front Panel Key Reference

KeyDescriptionsandLocations................................................110

AMPLITUDEYScale ........................................................111

Det/Demod ................................................................113

Display ...................................................................116

FREQUENCY/Channel .....................................................117

MeasSetup ................................................................119

MEASURE.................................................................123

MODE ....................................................................124

ModeSetup ................................................................125

Preset ....................................................................127

SPAN/XScale .............................................................128

Trig ......................................................................129

View/Trace ................................................................130

MonitorSpectrum .........................................................130

ErrorVectorMagnitude(EVM)...............................................130

Analysis

8. Programming Language Reference

ABORtSubsystem...........................................................132

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CALibrateSubsystem ....................................................... 133

RadioStandardCalibration................................................. 133

RadioStandardCalibration-Required........................................ 133

CONFigureSubsystem ......................................................134

ConfiguretheSelectedMeasurement ......................................... 134

DISPlaySubsystem......................................................... 135

DisplayViewingAngle ..................................................... 135

DateandTimeDisplayFormat .............................................. 135

DateandTimeDisplay .................................................... 136

DisplayAnnotationTitleData .............................................. 136

TurntheEntireDisplayOn/Off ............................................. 136

WindowAnnotation ....................................................... 136

TraceGraticuleDisplay.................................................... 137

SettheDisplayLine....................................................... 137

ControltheDisplayLine ................................................... 138

NormalizedReferenceLevel ................................................ 138

NormalizedReferenceLevelPosition ......................................... 138

TraceY-AxisAmplitudeScaling.............................................. 139

TraceY-AxisReferenceLevel ............................................... 139

VerticalAxisScaling ...................................................... 140

FETChSubsystem.......................................................... 141

FetchtheCurrentMeasurementResults ...................................... 141

INITiateSubsystem......................................................... 142

ContinuousorSingleMeasurements ......................................... 142

TakeNewDataAcquisitions ................................................ 143

PausetheMeasurement.................................................... 144

RestarttheMeasurement .................................................. 144

ResumetheMeasurement .................................................. 144

INSTrumentSubsystem ..................................................... 145

CatalogQuery............................................................ 145

SelectApplicationbyNumber ............................................... 145

SelectApplication......................................................... 146

MEASureGroupofCommands................................................ 147

MeasureCommands....................................................... 147

ConfigureCommands...................................................... 148

FetchCommands.......................................................... 148

ReadCommands.......................................................... 149

MonitorSpectrum......................................................... 150

ErrorVectorMagnitude(EVM) ..............................................150

READ Subsystem . . . ........................................................ 154

SENSeSubsystem .......................................................... 155

ChannelCommands....................................................... 155

DefaultReset ............................................................ 158

ErrorVectorMagnitudeMeasurement........................................ 158

FrequencyCommands ..................................................... 163

PhaseandQuadratureCommands ........................................... 165

MonitorSpectrumMeasurement ............................................ 166

Reference Oscillator Frequency . . . ........................................... 171

Reference Oscillator Rear Panel Output . . ..................................... 171

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Reference Oscillator Source .................................................171

RFPortInputAttenuation ..................................................172

RadioStandardsCommands.................................................172

SynchronizationCommands .................................................176

STATusSubsystem..........................................................177

OperationRegister ........................................................177

9. If You Have a Problem

IfyouhaveaProblem........................................................180

BeforeYouCallAgilentTechnologies ...........................................181

ChecktheBasics ..........................................................181

ReadtheWarranty ........................................................182

ServiceOptions ...........................................................182

GettingintouchwithAgilentTechnologies,Inc..................................182

HowtoReturnYourAnalyzerforService........................................184

ServiceTag...............................................................184

OriginalPackaging ........................................................184

OtherPackaging ..........................................................186

Analysis

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:ABORt..................................................................................132

:CALibration:WIDeband:REQuired?...........................................................133

:CALibration:WIDeband? ...................................................................133

:CONFigure:<measurement>.................................................................134

:CONFigure:<measurement>.................................................................148

:CONFigure:EVM .........................................................................150

:CONFigure:MON.........................................................................150

:DISPlay:ANGLe <integer> . . ................................................................135

:DISPlay:ANGLe? .........................................................................135

:DISPlay:ANNotation:CLOCk:DATE:FORMat MDY|DMY ........................................135

:DISPlay:ANNotation:CLOCk:DATE:FORMat? . . ...............................................135

:DISPlay:ANNotation:CLOCk[:STATe] OFF|ON|0|1 ..............................................136

:DISPlay:ANNotation:CLOCk[:STATe]? . . . ....................................................136

:DISPlay:ANNotation:TITLe:DATA <string> ....................................................136

:DISPlay:ANNotation:TITLe:DATA? ..........................................................136

:DISPlay:ENABleOFF|ON|0|1 ............................................................... 136

:DISPlay:WINDow:ANNotation[:ALL]OFF|ON|0|1.............................................. 136

:DISPlay:WINDow:ANNotation[:ALL]? .......................................................136

:DISPlay:WINDow:TRACe:GRATicule:GRID[:STATe]OFF|ON|0|1.................................137

:DISPlay:WINDow:TRACe:GRATicule:GRID[:STATe]?...........................................137

:DISPlay:WINDow:TRACe:Y:DLINe<ampl>...................................................137

:DISPlay:WINDow:TRACe:Y:DLINe:STATeOFF|ON|0|1..........................................138

:DISPlay:WINDow:TRACe:Y:DLINe:STATe?...................................................138

:DISPlay:WINDow:TRACe:Y:DLINe?.........................................................137

:DISPlay:WINDow:TRACe:Y[:SCALe]:NRLevel<rel_ampl> ......................................138

:DISPlay:WINDow:TRACe:Y[:SCALe]:NRLevel?...............................................138

:DISPlay:WINDow:TRACe:Y[:SCALe]:NRPosition<integer>...................................... 138

:DISPlay:WINDow:TRACe:Y[:SCALe]:NRPosition?.............................................138

:DISPlay:WINDow:TRACe:Y[:SCALe]:PDIVision<rel_ampl>.....................................139

:DISPlay:WINDow:TRACe:Y[:SCALe]:PDIVision?..............................................139

:DISPlay:WINDow:TRACe:Y[:SCALe]:RLEVel<ampl> ..........................................139

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:DISPlay:WINDow:TRACe:Y[:SCALe]:RLEVel?................................................ 139

:DISPlay:WINDow:TRACe:Y[:SCALe]:SPACingLINear|LOGarithmic .............................. 140

:DISPlay:WINDow:TRACe:Y[:SCALe]:SPACing?............................................... 140

:FETCh:<measurement>[n]?................................................................. 141

:FETCh:<measurement>[n]?................................................................. 148

:FETCh:EVM[n]?.........................................................................150

:FETCh:MON[n]?.........................................................................150

:INITiate:CONTinuous OFF|ON|0|1 . . . ........................................................ 142

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:INITiate:CONTinuous?. . ...................................................................142

:INITiate:PAUse........................................................................... 144

:INITiate:RESTart ......................................................................... 144

:INITiate:RESume......................................................................... 144

:INITiate[:IMMediate]...................................................................... 143

:INSTrument:CATalog?.....................................................................145

:INSTrument:NSELect<integer> .............................................................145

:INSTrument:NSELect?..................................................................... 145

:INSTrument[:SELect]SA|MAN.............................................................. 146

:INSTrument[:SELect]?.....................................................................146

:MEASure:<measurement>[n]?............................................................... 147

:MEASure:EVM[n]?.......................................................................150

:MEASure:MON[n]? ...................................................................... 150

:READ:<measurement>[n]? ................................................................. 149

:READ:EVM[n]? .........................................................................150

:READ:MON[n]? ......................................................................... 150

Analysis

:STATus:OPERation:CONDition?.............................................................177

:STATus:OPERation:ENABle<integer>........................................................177

:STATus:OPERation:ENABle?............................................................... 177

:STATus:OPERation:NTRansition<integer> .................................................... 178

:STATus:OPERation:NTRansition?............................................................178

:STATus:OPERation:PTRansition<integer>..................................................... 178

:STATus:OPERation:PTRansition?............................................................ 178

Commands

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:STATus:OPERation[:EVENt]?...............................................................178

[:SENSe]:CHANnel:BURSt NORMal|SYNC|ACCess .............................................155

[:SENSe]:CHANnel:BURSt?. ................................................................155

[:SENSe]:CHANnel:SLOT <integer> ..........................................................155

[:SENSe]:CHANnel:SLOT:AUTO OFF|ON|0|1 . . . ...............................................156

[:SENSe]:CHANnel:SLOT:AUTO?. . .......................................................... 156

[:SENSe]:CHANnel:SLOT?. . ................................................................155

[:SENSe]:CHANnel:TSCode <integer>.........................................................156

[:SENSe]:CHANnel:TSCode:AUTO OFF|ON|0|1. . ...............................................157

[:SENSe]:CHANnel:TSCode:AUTO? ..........................................................157

[:SENSe]:CHANnel:TSCode? ................................................................156

[:SENSe]:DEFaults.........................................................................158

[:SENSe]:EVM:AVERage:COUNt <integer> ....................................................158

[:SENSe]:EVM:AVERage:COUNt? . ..........................................................158

[:SENSe]:EVM:AVERage:TCONtrolEXPonential|REPeat .........................................159

[:SENSe]:EVM:AVERage:TCONtrol? .........................................................159

[:SENSe]:EVM:AVERage[:STATe]OFF|ON|0|1..................................................158

[:SENSe]:EVM:AVERage[:STATe]?...........................................................158

[:SENSe]:EVM:BSYNc:SOURce RFAMplitude|NONE. . . .........................................159

[:SENSe]:EVM:BSYNc:SOURce?............................................................159

[:SENSe]:EVM:DROop:COMPensation?.......................................................159

[:SENSe]:EVM:DROop:COMPensation[:STATe]OFF|ON|0|1 ......................................159

[:SENSe]:EVM:GSDOTs[:STATe]ON|OFF|1|0 ..................................................160

[:SENSe]:EVM:GSDOTS[:STATe]? ...........................................................160

[:SENSe]:EVM:IQOOffset<integer> ..........................................................160

[:SENSe]:EVM:IQOOffset?..................................................................160

[:SENSe]:EVM:IQPoints<integer>............................................................160

[:SENSe]:EVM:IQPoints?...................................................................161

[:SENSe]:EVM:MIXer:RANGe[:UPPer] <power>. ...............................................161

[:SENSe]:EVM:MIXer:RANGe[:UPPer]?. . . ....................................................161

[:SENSe]:EVM:PPSYmbol ONE|TWO|FOUR|FIVE|TEN . .........................................161

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[:SENSe]:EVM:PPSYmbol?................................................................. 161

[:SENSe]:EVM:ROTation[:STATe]ON|OFF|1|0..................................................162

[:SENSe]:EVM:ROTation[:STATe]?...........................................................162

[:SENSe]:EVM:SDOTS[:STATe]OFF|ON|0|1................................................... 162

[:SENSe]:EVM:SDOTS[:STATe]? ............................................................ 162

[:SENSe]:EVM:SWEep:POINts<integer>......................................................163

[:SENSe]:EVM:SWEep:POINts? ............................................................. 163

[:SENSe]:EVM:TRIGger:SOURceIMMediate|EXTernal|RFBurst ................................... 163

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[:SENSe]:EVM:TRIGger:SOURce?...........................................................163

[:SENSe]:FREQuency:CENTer<freq>.........................................................163

[:SENSe]:FREQuency:CENTer?.............................................................. 163

[:SENSe]:FREQuency:SPAN<freq>...........................................................164

[:SENSe]:FREQuency:SPAN?................................................................ 164

[:SENSe]:FREQuency:STARt<freq>..........................................................164

[:SENSe]:FREQuency:STARt?............................................................... 164

[:SENSe]:FREQuency:STOP<freq>........................................................... 165

[:SENSe]:FREQuency:STOP?................................................................ 165

[:SENSe]:IQInvert[:STATe]ON|OFF|1|0 .......................................................165

[:SENSe]:IQInvert[:STATe]?.................................................................165

[:SENSe]:MONitor:AVERage:COUNt <integer> ................................................. 166

[:SENSe]:MONitor:AVERage:COUNt? ........................................................166

[:SENSe]:MONitor:AVERage:TCONtrolEXPonential|REPeat...................................... 167

[:SENSe]:MONitor:AVERage:TCONtrol? ......................................................167

[:SENSe]:MONitor:AVERage[:STATe]OFF|ON|0|1 .............................................. 167

Analysis

[:SENSe]:MONitor:AVERage[:STATe]?........................................................167

[:SENSe]:MONitor:CHANnel:BWIDth|BANDwidth:VIDeo <freq> . .................................168

[:SENSe]:MONitor:CHANnel:BWIDth|BANDwidth:VIDeo? ....................................... 168

[:SENSe]:MONitor:CHANnel:BWIDth|BANDwidth[:RESolution] <freq> ............................ 167

[:SENSe]:MONitor:CHANnel:BWIDth|BANDwidth[:RESolution]?. .................................167

[:SENSe]:MONitor:CHANnel:DETectorPOSitive|SAMPle|NEGative................................ 168

[:SENSe]:MONitor:CHANnel:DETector?....................................................... 168

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[:SENSe]:MONitor:CHANnel:MAXHold[:STATe] ON|OFF|1|0 . . ...................................169

[:SENSe]:MONitor:CHANnel:MAXHold[:STATe]?...............................................169

[:SENSe]:MONitor:CHANnel:SWEep:TIME <seconds> . . .........................................169

[:SENSe]:MONitor:CHANnel:SWEep:TIME:AUTO OFF|ON|0|1. ...................................170

[:SENSe]:MONitor:CHANnel:SWEep:TIME:AUTO? .............................................170

[:SENSe]:MONitor:CHANnel:SWEep:TIME? ...................................................169

[:SENSe]:MONitor:TRIGger:SOURce:IMMediate|EXTernal|RFBurst................................170

[:SENSe]:MONitor:TRIGger:SOURce? ........................................................170

[:SENSe]:OPTion:ROSCillator:EXTernal:FREQuency<Hz>........................................171

[:SENSe]:OPTion:ROSCillator:OUTPut?.......................................................171

[:SENSe]:OPTion:ROSCillator:OUTPut[:STATe]OFF|ON|0|1.......................................171

[:SENSe]:OPTion:ROSCillator:SOURceINTernal|EXTernal........................................171

[:SENSe]:OPTion:ROSCillator:SOURce?....................................................... 171

[:SENSe]:POWer[:RF]:ATTenuation<rel_power>................................................172

[:SENSe]:POWer[:RF]:ATTenuation?..........................................................172

[:SENSe]:RADio:STANdard:ALPHA<alpha/BTnumber>........................................172

[:SENSe]:RADio:STANdard:ALPHA?.........................................................172

[:SENSe]:RADio:STANdard:DEVice[:SELect]BTS|MS...........................................173

[:SENSe]:RADio:STANdard:DEVice[:SELect]?..................................................173

[:SENSe]:RADio:STANdard:FILTer:MEASurement?..............................................173

[:SENSe]:RADio:STANdard:FILTer:REFerence?.................................................174

[:SENSe]:RADio:STANdard:MODulationQPSK|P4DQPSK|OQPSK.................................174

[:SENSe]:RADio:STANdard:MODulation? .....................................................174

[:SENSe]:RADio:STANdard:SRATe<symbolrate>...............................................175

[:SENSe]:RADio:STANdard:SRATe?..........................................................175

[:SENSe]:RADio:STANdard[:SELect]? ........................................................175

[:SENSe]:SYNC:BURSt:SLENgth<value>.....................................................176

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[:SENSe]:SYNC:BURSt:SLENgth?...........................................................176

[:SENSe]:SYNC:BURSt:STHReshold<rel_power> .............................................. 176

[:SENSe]:SYNC:BURSt:STHReshold? ........................................................ 176

Analysis

1 Using This Document

This chapter describes the organization of this reference guide.

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Using This Document

Book Organization

This book includes both user and programmer information. The first seven chapters cover user information such as how to set up and use the instrument.

Chapter 8 , “Programming Language Reference,” covers the SCPI remote

programming commands.

The following table gives a brief overview of each chapter.

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Table 1-1 Book Organization

1. Using this Document

This chapter.

2. Understanding Modulation Analysis

See page 19.

3. Getting Started

See page 37.

This chapter describes the organization of this book.

This chapter defines modulation analysis and describes its characteristics.

This chapter describes how to install and uninstall this measurement personality.

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Using This Document

Book Organization

4. Setting Up the Modulation Analysis Mode

See page 49.

5. Making Modulation Analysis Measurements

See page 53.

6. Menu Maps

See page 93.

This chapter describes how to set the instrument up to perform modulation analysis measurements.

This chapter describes how to make standard and custom measurements and interpret the results.

This chapter illustrates the menu structure of the front panel and lower-level keys. Refer to this chapter to identify the lower-level softkeys associated with the front panel keys.

7. Front Panel Key Reference

See page 109.

8. Programming Language Reference

See page 131.

This chapter describes the instrument front panel and menu keys. The front panel keys are arranged alphabetically, and the menu keys are arranged as they appear on the instrument menus.

These are the SCPI commands available in EVM mode.

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Book Organization

Table 1-1 Book Organization

9. If You Have a Problem

See page 179.

This chapter includes information on basic troubleshooting and contacting Agilent.

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Analysis

2 Understanding Modulation Analysis

The modulation analysis personality will support base-band modulation analysis for several industry standards. This chapter introduces you to the basics of some of the most common formats and the general functionality of the ESA with the modulation analysis measurement personality installed. Sources for additional information on digital communications are also listed.

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Understanding Modulation Analysis

Digital Communication Systems Standards Overview

The cdmaOne (IS-95) Communication System

IS-95 code division multiple access (cdmaOne) is one of several digital wireless transmission methods in which signals are encoded using a specific pseudo-random sequence, or code, to define a communication channel. A receiver, knowing the code, can use it to decode the received signal in the presence of other signals in the channel. This is one of several "spread spectrum" techniques, which allows multiple users to share the same radio frequency spectrum by assigning each active user a unique code. cdmaOne offers improved spectral efficiency over analog transmission in that it allows for greater frequency reuse. Other characteristics of cdmaOne systems reduce dropped calls, increase battery life and offer more secure transmission.

The W-CDMA Communication System

Wideband code division multiple access (W-CDMA) is the first of the supported air interface technologies for the third generation RF cellular communication systems. In this system, the cells operate asynchronously. Hence, it makes the mobile synchronization more complex, but offers the advantage of flexibility in placement of the base stations. Both reverse and forward transmitter power controls are implemented with 0.625 ms intervals. W-CDMA is a direct sequence spread spectrum digital communications technique that supports a wider RF bandwidth of 5 MHz.

The CDMA2000 Communication System

Code division multiple access 2000 (cdma2000) is the second of the supported popular wideband air interface technologies for the third generation RF cellular communication systems. This system relies on the Global Positioning System (GPS) for intercell synchronization. Both reverse and forward transmitter power controls are implemented with 1.25 ms intervals. cdma2000 is a direct sequence spread-spectrum digital communications technique that supports a wide RF bandwidth of 1.25 MHz.

W-CDMA and cdma2000 Advantages

Analysis

The main advantages of cdma2000 and W-CDMA over other types of communication schemes are:

• Greater capacity

• Immunity to signal loss and degradation due to high-level broadband interference, multipath scattering and fading

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Digital Communication Systems Standards Overview

• Power consumption of mobile stations is strictly minimized by base station and mobile controls

• Supports variable data rates up to 144 kbits/second for mobile (vehicular) data rate, up to 384 kbits/second for portable (pedestrian) data rate, and up to 2 Mbits/second for fixed installations

• Provides increased security

W-CDMA and cdma2000 use correlative codes to distinguish one user from another. Frequency division (FDMA) and Time Division (TDMA) are also used. Frequency division is used in a much larger bandwidth such as

1.25 MHz or greater for cdma 2000 and 5 MHz or greater for W-CDMA.

For W-CDMA, an initial baseband data rate is spread to a transmitted data rate of 3.840 Mcps, which is also called chip rate or spread data rate. W-CDMA and cdma2000 both realize increased capacity from frequency reuse and sectored cells. The capacity limit is soft. That is, capacity can be increased with some degradation of the error rate or voice quality.

In W-CDMA and cdma2000, a single user's channel consists of a specific frequency combined with a unique code. Correlative codes allow each user to operate in the presence of substantial interference. The interference is the sum of all other users on the same W-CDMA or cdma2000 frequency, both from within and outside of the home cell, and from delayed versions of these signals. It also includes the usual thermal noise and atmospheric disturbances. Delayed signals caused by multipath are separately received and combined in these systems. One of the major differences in access is that any frequency can be used in all sectors of all cells. This is possible because the W-CDMA and cdma2000 systems are designed to decode the proper signal in the presence of high interference.

Additionally, cdma2000 offers a number of RF structures to accommodate almost any conceivable application. These options include direct spreading to support those applications where clear spectrum is available and multicarrier arrangements using 1.25 MHz wide channels to allow overlays with TIA/EIA-95-B systems.

W-CDMA (3GPP) is defined in the following documents:

• TS 25.XX series 3rd Generation Partnership Project Technical Specification; Radio Performance aspects. These documents define complex multipart measurements used to maintain an interference free environment.

There are many other formats supported by the modulation analysis personality that can be referenced by the appropriate standards documents.

cdma2000 is defined in the following Telecommunications Industry Association (TIA) and Electronics Industry Alliance (EIA) document:

• TIA/EIA/IS-2000 Mobile Station - Base Station Compatibility Standard

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for Dual-Mode Wideband Spread Spectrum Cellular System

cdmaOne Standards

The cdmaOne communication system personality is defined in the following standard bodies: Electronics Industry Association (EIA), Telecommunications Industry Association (TIA), American National Standards Institute (ANSI), Association of Radio Industries and Businesses (ARIB) (Japan), and Korean standards documents:

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IS-95-A:

TIA/EIA-IS-95-A Mobile Station-Base Station Compatibility Standard for Dual-Mode

Wideband Spread Spectrum Cellular System. May 1995

TIA/EIA-IS-97-A Recommended Minimum Performance Standards for Base Stations

Supporting Dual-Mode Wideband Spread Spectrum Cellular Mobile Stations. July 1996

TIA/EIA-IS-98-A Recommended Minimum Performance Standards for Dual-Mode Wideband

Spread Spectrum Cellular Mobile Stations. July 1996

TIA/EIA-95-B Cell and TIA/EIA-95-B PCS:

TIA/EIA-95-B Mobile Station-Base Station Compatibility Standard for Dual-Mode Spread

Spectrum Systems. (SP-3693-1) July 17, 1998

TIA/EIA-97-B Recommended Minimum Performance Standards for Base Stations

Supporting Dual-Mode Spread Spectrum Cellular Mobile Stations. August 1998

TIA/EIA-98-B Recommended Minimum Performance Standards for Dual-Mode Spread

Spectrum Cellular Mobile Stations. August 1998

95-C Cell and 95-C PCS:

TIA/EIA-95-B Mobile Station-Base Station Compatibility Standard for Dual-Mode Spread

Spectrum Systems. (SP-3693-1) July 17, 1998

TIA/EIA-97-C Recommended Minimum Performance Standards for Base Stations

Supporting Dual-Mode Spread Spectrum Mobile Stations. (SP-4384) Ballot Version: Nov. 20, 1998

TIA/EIA-98-C Recommended Minimum Performance Standards for Dual-Mode Spread

Spectrum Mobile Stations. (SP-4383) Ballot Version: March. 19, 1999

ANSI J-STD-008:

ANSI J-STD-008 Personal Station-Base Station Compatibility Requirements for 1.8 to 2.0 GHz

Code Division Multiple Access (CDMA) Personal Communications Systems. August 29, 1995.

ANSI J-STD-018 Recommended Minimum Performance Requirements for 1.8 to 2.0 GHz

Code Division Multiple Access (CDMA) Personal Stations. (SP-3385) January 16, 1996

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ANSI J-STD-019 Recommended Minimum Performance Requirements for Base Stations

Supporting 1.8 to 2.0 GHz Code Division Multiple Access (CDMA) Personal Stations. (SP-3383) January 12, 1996

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The NADC Communications System

The North American Dual-Mode Cellular (NADC) is one of the cellular communications systems. NADC is also referred to as North American Digital Cellular, or American Digital Cellular (ADC). Occasionally, it is also referred to as Digital Advanced Mobile Phone Service (D-AMPS) or NADC-TDMA. The NADC communications system is defined in the Electronics Industry Alliance (EIA) and Telecommunication Industry Association (TIA) standard documents. The following is a list of all relevant and applicable standard documents:

TIA/EIA IS-136.1 TDMA Cellular/PCS - Radio Interface - Mobile Station - Base Station

Compatibility - Digital Control Channel

TIA/EIA IS-136.2 TDMA Cellular/PCS - Radio Interface - Mobile Station - Base Station

Compatibility - Traffic Channels and FSK Control Channel

TIA/EIA IS-137 TDMA Cellular/PCS - Radio Interface - Minimum Performance Standards

for Mobile Stations

TIA/EIA IS-138 TDMA Cellular/PCS - Radio Interface - Minimum Performance Standards

for Base Stations

TIA/EIA-627 800 MHz Cellular System, TDMA Radio Interface, Dual-Mode Mobile

Station - Base Station Compatibility Standard (ANSI/TIA/EIA-627-96), which replaced IS-54-B

TIA/EIA-628 800 MHz Cellular System, TDMA Radio Interface, Dual-Mode Mobile

Station - Base Station Compatibility Standard (ANSI/TIA/EIA-627-96), which replaced IS-54-B

TIA/EIA-629 800 MHz Cellular System, TDMA Radio Interface, Minimum Performance

Standards for Base Stations Supporting Dual-Mode Mobile Stations (ANSI/TIA/EIA-629-96), which replaced IS-56-A

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The GSM Standards

The Global System for Mobile communication (GSM) digital communications standard defines a voice and data over-air interface between a mobile radio and the system infrastructure. This standard was designed as the basis for a radio communications system. A base station control center (BSC) is linked to multiple base transceiver station (BTS) sites which provide the required coverage.

GSM 450, GSM 480, GSM 850, GSM 900, DCS 1800, and PCS 1900 are GSM-defined frequency bands. The term GSM 900 is used for any GSM system operating in the 900 MHz band, which includes P-GSM, E-GSM, and R-GSM. Primary (or standard) GSM 900 band (P-GSM) is the original GSM band. Extended GSM 900 band (E-GSM) includes all the P-GSM band plus an additional 50 channels. Railway GSM 900 band (R-GSM) includes all the E-GSM band plus additional channels. DCS 1800 (in the 1800 MHz frequency band) is an adaptation of GSM 900, created to allow for smaller cell sizes for higher system capacity. PCS 1900 (in the 1900 MHz frequency band) is intended to be identical to DCS 1800 except for frequency allocation and power levels. PCS 1900 is used primarily in the USA. The term GSM 1800 is sometimes used for DCS 1800, and the term GSM 1900 is sometimes used for PCS 1900. For specifics on the bands, refer to Tab le 2-1.

The standard includes multiple traffic channels, a control channel, and a cell broadcast channel. The GSM specification defines a channel spacing of 200 kHz.

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MHz

824.2 - 848.8

MHz

479.0 - 485.8

MHz

450.6 - 457.4

MHz

1850 - 1910

MHz

1710 - 1785

MHz

869.0 - 894.0

MHz

489.0 - 495.8

MHz

460.6 - 467.4

MHz

1930 - 1990

MHz

1805 - 1880

512 to 885 512 to 810 259 to 293 306 to 340 128 to 251

270.833

kbits/s

921 - 960

925 - 960

935 - 960

MHz

955 to 1023

1 to 124 and

MHz

975 to 1023

MHz

1 to 124 0 to 124 and

45 MHz 45 MHz 45 MHz 95 MHz 80 MHz 45 MHz 45 MHz 45 MHz

3 timeslots 3 timeslots 3 timeslots 3 timeslots 3 timeslots 3 timeslots 3 timeslots 3 timeslots

270.833

kbits/s

576.9 µs576.9µs 576.9 µs 576.9 µs 576.9 µs 576.9 µs 576.9 µs 576.9 µs

200 kHz 200 kHz 200 kHz 200 kHz 200 kHz 200 kHz 200 kHz 200 kHz

MHz

876 - 915

MHz

880 - 915

MHz

890 - 915

P-GSM 900 E-GSM 900 R-GSM 900 DCS 1800 PCS 1900 GSM450 GSM480 GSM850

Analysis

Modulation 0.3 GMSK 0.3 GMSK 0.3 GMSK 0.3 GMSK 0.3 GMSK 0.3 GMSK 0.3 GMSK 0.3 GMSK

Channel

Spacing

Range

(ARFCN)

TX/RX Spacing

(Freq.)

TX/RX Spacing

(Time)

Modulation

Data Rate

Frame Period 4.615 ms 4.615 ms 4.615 ms 4.615 ms 4.615 ms 4.615 ms 4.615 ms 4.615 ms

Downlink

(BTS

Uplink

Table 2-1 GSM Band Data

(MS Transmit)

Transmit)

Timeslot

Bit Period 3.692 µs 3.692 µs 3.692 µs 3.692 µs 3.692 µs3.692µs3.692µs 3.692 µs

Period

TDMA Mux 88888888

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Digital Communication Systems Standards Overview

The GSM framing structure is based on a hierarchical system consisting of timeslots, TDMA frames, multiframes, superframes, and hyperframes. One timeslot (or RF burst) consists of 148 bit periods including training sequence, encryption, guard time, and data bits. Eight of these timeslots make up one TDMA frame. Either 26 or 51 TDMA frames make up one multiframe. Frames 13 and 26 in the 26 frame multiframe are dedicated to control channel signaling.

These principles of the GSM systems lead to the need for the fundamental transmitter measurements, one of which is Phase and Frequency Error which verifies the accuracy of the transmitter’s 0.3 GMSK modulation process.

NOTE A full suite of GSM measurements (including Power vs. Time and Output RF

Spectrum) can be performed with Option BAH.

Mobile Stations And Base Transceiver Stations

The cellular system includes the following:

• base transceiver stations, referred to as BTS (frequency ranges dependent on the standard; refer to Table 2-1)

• mobile stations, referred to as MS (frequency ranges dependent on the standard; refer to Table 2-1)

Uplink And Downlink

Uplink is defined as the path from the mobile station to the base transceiver station. Downlink is the path from the base transceiver station to the mobile station.

What Is An ARFCN?

An ARFCN is the Absolute Radio Frequency Channel Number used in the GSM system. Each RF channel is shared by up to eight mobile stations using Time Division Multiple Access (TDMA). The ARFCN is an integer (in a range dependent on the chosen standard, refer to Table 2-1) which designates the carrier frequency.

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What Is A Timeslot?

GSM utilizes Time Division Multiple Access (TDMA) with eight time slots per RF channel which allows eight users to use a single carrier frequency simultaneously. Users avoid one another by transmitting in series. The eight users can transmit once every 4.62 ms for 1 timeslot which is 577 µs long. The eight user timeslots are numbered from 0 to 7.

Typically, each 577 µs timeslot has a length of 156.25 bit periods, which consists of 148 data bits and 8.25 guard bits. The 4.62 ms required to cycle through eight timeslots is called a frame. In a TDMA system, the shape of each transmitted burst must be controlled carefully to avoid over-lapping bursts in time.

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The EDGE Standard

What is EDGE with GSM?

EDGE (Enhanced Data Rates for GSM Evolution) enhances the GSM standard with a new modulation format (8PSK with 3pi/8 rotation) and filtering designed to provide higher data rates in the same spectrum. EDGE allows more bits to be sent in each burst. This increases the number of bits per symbol, and provides a 3-fold increase in data rate over GSM’s GMSK (Gaussian Minimum Shift Keying) modulation format.

NOTE EDGE has also been adopted as the basis for IS-136HS (NADC + EDGE) signals.

GSM 450, GSM 480, GSM 850, GSM 900, DCS 1800, and PCS 1900 are GSM-defined frequency bands. The term GSM 900 is used for any EDGE (with GSM) system operating in the 900 MHz band, which includes P-GSM, E-GSM, and R-GSM. Primary, or standard, GSM 900 band (P-GSM) is the original GSM band. Extended GSM 900 band (E-GSM) includes all the P-GSM band plus an additional 50 channels. Railway GSM 900 band (R-GSM) includes all the E-GSM band plus additional channels. DCS 1800 is an adaptation of GSM 900, created to allow for smaller cell sizes for higher system capacity. PCS 1900 is intended to be identical to DCS 1800 except for frequency allocation and power levels. The term GSM 1800 is sometimes used for DCS 1800, and the term GSM 1900 is sometimes used for PCS 1900.

The GSM digital communications standard employs an 8:1 Time Division Multiple Access (TDMA) allowing eight channels to use one carrier frequency simultaneously. The 270.833 kbits/second raw bit rate is modulated on the RF carrier using Gaussian Minimum Shift Keying (GMSK).The standard includes multiple traffic channels (TCH), a control channel (CCH), and a broadcast control channel (BCCH). The GSM specification defines a channel spacing of 200 kHz.

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EDGE employs the same symbol rate and frame structure as GSM. EDGE and GSM signals can be transmitted on the same frequency, occupying different timeslots, and both use existing GSM equipment. Due to the similarity between the formats, the transmitter measurements are the same, with the addition of only a few EDGE-specific measurements. One of them is:

EDGE EVM It provides a measure of modulation accuracy. EDGE

8PSK modulation pattern uses a rotation of 3p/8 radians to avoid zero crossing, thus affording some margin of linearity relief for amplifier performance. It is substantially more demanding than GSM modulation (GMSK), and EDGE EVM testing is necessary to reveal performance shortcomings.

The EDGE format is defined in the following standards documents: GSM 05.04, 05.05, 11.10, 11.21, and ANSI J-STD-007 specifications. These documents define complex, multi-part measurements used to maintain an interference-free environment. For example, the documents include measuring the power of a carrier.

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The PDC Standard

Personal Digital Cellular (PDC) is one of the cellular communications systems in Japan. The digital modulation format used in the PDC system is the pi/4 differential quadrature phase shift keying (pi/4 DQPSK). The pi/4 DQPSK modulation causes both phase and amplitude variations on the RF signal. The quadrature nature of this modulation allows 2 bits to be transmitted at the same time on orthogonal carriers. These 2 bits make one PDC symbol.The PDC communications system is defined in the Association of Radio Industries and Business (ARIB) document, RCR STD-27, Personal Digital Cellular Telecommunication System Standard.

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The TETRA Standard

TErrestrial Trunked RAdio (TETRA) is the modern digital Private Mobile Radio (PMR) and Public Access Mobile Radio (PAMR) technology for police, ambulance and fire services, security services, utilities, military, public access, fleet management, transport services, closed user groups, factory site services and mining. TETRA uses Time Division Multiple Access (TDMA) technology with 4 user channels on one radio carrier and 25 kHz spacing between carriers. This makes it inherently efficient in the way that it uses the frequency spectrum.

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What the Modulation Analysis Measurement Personality Does

The Agilent ESA-E Series Spectrum Analyzer with the modulation analysis measurement personality can help identify common impairments to digitally modulated signals for all the major communication formats.

There are two ways to configure the analyzer for digital demodulation measurements. You can manually enter values for all demodulation parameters, or you can specify the standard of your digital communications system and let the analyzer automatically set the parameters.

The analyzer lets you select from several standards. When you select a standard, the analyzer automatically sets the parameters shown in the following table.

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Table 2-2 Radio Format Settings

Radio

Format

cdmaOne BTS QPSK 1.2288

cdmaOne MS Offset

cdma2000

SR1

Device

Demod

Format

Symbol Rate

MS/s

1.2288

QPSK

BTS QPSK 1.2288

MS/s

Meas Filter

cdma BS

Ph EQ

Off Chebyshev n/a 4 200 3 MHz –20 dB 1 s None 4 Off

cdma BS

Ph EQ

Ref Filter

Chebyshev n/a 5 200 3 MHz –20 dB 1 s None 5 Off

Chebyshev n/a 5 256 3 MHz –20 dB 1 s None 5 Off

Alpha/BT

Points/Symbol

Measurement Interval or

Result Length

Frequency Span

Burst Search Thresh old

Burst Search Length

Burst Sync

(Under EVM MeasSetup)

I/Q Points

I/Q Invert

cdma2000

SR1

W-CDMA

3GPP

NADC BTS Pi/4

NADC MS Pi/4

EDGE

(8PSK)

EDGE

(8PSK)

GSM

(GMSK)

PDC BTS Pi/4

PDC MS Pi/4

TETRA BTS Pi/4

TETRA MS Pi/4

MS QPSK 1.2288

BTS &MSQPSK 3.84 MS/ s Root

DQPSK

BTS PSK

EDGE

MS PSK

EDGE

BTS &MSMSK 270.833

DQPSK

Off Chebyshev n/a 5 256 3 MHz –20 dB 1 s None 5 Off

MS/s

Nyquist

24.3 kS/s Root

Nyquist

24.3 kS/s Root

Nyquist

270.833 kS/s

kS/s

21.0 kS/s Root

18.0 kS/s Root

EDGE

(winRC)

EDGE

(winRC)

Off Gauss 0.3 10 146 60 0

Nyquist

Nyquist 0.22 5 256 6 MHz –20 dB 1 s None 5 Off

Nyquist 0.35 5 162 100

Nyquist 0.35 5 157 100

EDGE 0.25 1 142 600

Nyqui st 0.5 5 138 100

Nyqui st 0.5 5 135 100

Nyquist 0.35 5 246 100

Nyquist 0.35 5 231 100

–20dB 49ms None 5 Off

kHz

–20dB 49ms RF

kHz

–20 dB 5.3 ms Training

kHz

–20 dB 5.3 ms Training

kHz

–20 dB 5.3 ms Training

kHz

–20dB 48ms None 5 Off

kHz

–20dB 48ms RF

kHz

–20dB 73ms None 5 Off

kHz

–20dB 73ms RF

kHz

5Off

Amptd.

1Off

Seq.

1Off

Seq.

10 Off

Seq.

5Off

Amptd.

5Off

Amptd.

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What the Modulation Analysis Measurement Personality Does

The ESA spectrum analyzer with modulation analysis measurement personality is capable of making the following measurements on the appropriate or relevant standards:

•PeakandRMSEVM

• Peak and RMS magnitude error

• Peak and RMS phase error

• Frequency Error

• Phase error/symbol display

• Magnitude error versus symbol display

• Polar vector display

• Polar constellation display

• I and Q eye display

• I/Q Offset

• Amplitude Droop error

In addition to the measurements listed above, the modulation analysis personality provides or uses the following supplemental functions:

• Wideband Calibration which allows the user to effectively perform a factory calibration on the analyzer's front end.

• Automatic signal level detection and analyzer setup.

• External reference configuration and control.

• Save and recall mode state (Mode is the operation mode of the instrument. For example: SA = Spectrum Analyzer or MAN = Modulation Analysis Measurement personality)

• Storing/printing of results internally or directly to a floppy disk in spreadsheet (.csv) format.

• Link to a PC running Agilent’s 89600 VSA Vector Signal Analysis software. This allows in-depth time, frequency and modulation domain analysis of many RF signals up to 10 MHz in bandwidth, including AM, FM,PM,BPSK,QPSK,8PSK,DQPSK,pi/4DQPSK,FSK,GMSK, 16-256QAM, DVB, VSB, 3GPP and cdma2000. To order a free demo CD, visit our website at www.agilent.com/find/89600.

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Other Sources of Measurement Information

Additional measurement application information is available through your local Agilent Technologies sales and service office, or from Agilent’s web site at http://www.agilent.com. The following application notes provide more detail on digital communications and measurements.

• Application Note 1298 Digital Modulation in Communications Systems - An Introduction HP/Agilent part number 5965-7160E

• Application Note 1311 Understanding CDMA Measurements for Base Stations and Their Components HP/Agilent part number 5968-0953E

• Application Note 1313 Testing and Troubleshooting Digital RF Communications Transmitter Designs HP/Agilent part number 5968-3578E

• Application Note 1314 Testing and Troubleshooting Digital RF Communications Receiver Designs HP/Agilent part number 5968-3579E

• Application Note 150 Spectrum Analyzer Basics

HP/Agilent part number 5952-0292

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3 Getting Started

This chapter introduces you to basic features of the instrument, including the front panel keys, rear panel connections, and display annotation. Equipment required for modulation analysis measurements, available documentation, and processes for installing and uninstalling this measurement personality are also described.

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Getting Started

Instrument Overview

This section provides information on only Modulation Analysis mode features. For those features not described here, refer to the Agilent ESA Spectrum Analyzers

User’s Guide.

Front-Panel Features

For further information on the features mentioned in the following section, refer to

Chapter 7 , “Front Panel Key Reference,” of this document.

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Figure 3-1 Front-Panel Feature Overview

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Ta bl e 3- 1 K e y t o Figure 3-1 Front-Panel Feature Overview (above)

1Modekeys

These keys allow you to select the measurement mode and mode parameters such as input and trigger settings.

•

MODE accesses menu keys to select the instrument mode. Each mode is independent of

all other modes.

•

Mode Setup accesses menu keys that allow you to configure the parameters specific to

the current mode and affect all measurements within that mode.

38 Chapter 3

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Rear-Panel Features

This section provides information on Modulation Analysis rear panel features only. For those features not described here, refer to the ESA-E Series Spectrum Analyzers User’s Guide.

Figure 3-2 Rear-Panel Feature Overview

Getting Started

Instrument Overview

Measurements

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Ta bl e 3- 2 K e y t o Figure 3-2 Rear-Panel Feature Overview (above)

1 DSP and Fast

ADC

2RFComms

Hardware

3ExtRefIn Accepts an external 1 MHz to 30 MHz reference frequency source.

410MHzREFIN Accepts an external frequency source to provide the 10 MHz, −15 to +10 dBm

5 10 MHz Out Provides a 10 MHz, 0 dBm minimum, timebase reference signal phase locked to the

610MHzREF

OUT

7 Ext Frame Sync Acceptsanexternal0to5VTTLtrigger.

DSP and Fast ADC (Option B7D) provides digital signal processing and fast ADC required for many of the digital demodulation measurements in the Modulation Analysis and other measurement personalities. It must be ordered with Option B7E andOption1D5.

RF Communications Hardware (Option B7E) provides the RF down convertor hardware required for digital demodulation measurements. It must be ordered with Option B7D and Option 1D5.

frequency reference used by the analyzer.

Ext Ref In.

Provides a 10 MHz, 0 dBm minimum, timebase reference signal.

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Options Required

Installing the Modulation Analysis measurement personality firmware and making the associated measurements require certain basic equipment. This section lists Modulation Analysis compatible Agilent ESA Spectrum Analyzers and required hardware options.

Compatible Spectrum Analyzers

The Modulation Analysis measurement personality is not compatible with all ESA spectrum analyzer models. Table 3-3 lists the models that are compatible and the upper frequency range of each.

Table 3-3 Modulation Analysis Compatible Agilent ESA Spectrum Analyzers

Model Number Upper Frequency Range

E4402B 3 GHz

E4404B 6.7 GHz

E4405B 13.2 GHz

E4407B 26.5 GHz

Hardware Options Required

Additional hardware options must be installed in the spectrum analyzer before Modulation Analysis measurements can be made. Table 3-4 lists the hardware options required for optimum performance of Modulation Analysis measurements.

Not all of the options can be installed by the user. Some of the options require that the instrument be returned to the factory or an Agilent Technologies service center. In addition, some of the options require Performance Verification and Adjustments to be performed after installation. Refer to Table 3-4 for option specific information.

NOTE When transporting the instrument, use the original packaging or comparable

packaging. If the shipping container is damaged, any part is missing, or you do not have an appropriate shipping container, notify Agilent Technologies at one of the addresses shown on “Getting in touch with Agilent Technologies, Inc.” on page

182.

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Table 3-4 Modulation Analysis Hardware Options and Measurements

Required/recommended

option

Modulation Analysis Personality 229 Required for all measurements.

Memory extension B72

DSP and Fast ADC

RF Communications Hardware

High Stability Frequency Reference

RF and Digital Communication Hardware Option bundle

Option

Number

B7D

B7E

1D5

Option B74 Includes the following options: 1D6 B72 1D5 B7D B7E 1DS 1DR

Comments

Required

Recommended

Includes necessary hardware for the modulation analysis measurements personality.

a. Service center or factory installation; calibration required. b. Factory installation only.

NOTE If the appropriate hardware is not present, the measurement softkey under the

Measure menu will be grayed out and that measurement will not be available.

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Installing Optional Measurement Personalities

Active License Key

The measurement personality software you have purchased with your instrument has been installed and the license key has been enabled at the factory. With any future purchase of a new personality software, you will receive a certificate that displays the unique license key number. The license key enables you to install, or reinstall, any measurement personality you have purchased. If you return the instrument to the factory for the installation of measurement personality software, you will receive no documentation of the license key number, nor will you receive documentation of the license key number for the measurement personality software you have purchased with your instrument.

Installing the Licensing Key

If you are installing a new option, follow these steps to install the unique license key number for the measurement personality software that you want to install in your instrument:

1. Press

2. Use the alpha editor to enter the three letter designation for the software option

3. Press

4. Press

5. Use the alpha editor to enter the 12 character licensing key number for the

6. Press

7. Press

System, More, Licensing, Option.

When you press using the alpha editor, refer to the Agilent ESA Spectrum Analyzers User’s Guide.

that you wish to install in the instrument.

Done on the alpha editor menu.

License Key.

When you press instructions on using the alpha editor, refer to the Agilent ESA Spectrum Analyzers User’s Guide.

software option that you wish to install in the instrument.

Done on the alpha editor menu.

Activate to turn on the licensing key. You may now install the

measurement personality option software.

Option the alpha editor will be activated. For instructions on

Licensing Key the alpha editor will be activated. For

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Using the Install Key

You may want to install a software revision, install new measurement software or reinstall measurement software that you have previously uninstalled, or uninstall measurement software. Before you can install software, you will need a set of installation diskettes.

If you have ordered a measurement personality, you will receive the installation disk set in the option upgrade package. If you are updating an existing, previously installed measurement option, you may order the diskettes from Agilent Technologies or create a set from the Agilent internet site shown in “Updating the

Firmware” on page 48. When you order the updated software disk set, you will

need to order Option UE2. (Option UE2 is a firmware update and is needed to ensure that the firmware and the software are compatible.) A set of diskettes can be ordered from your local Agilent Technologies service or sales office. Refer to

“Getting in touch with Agilent Technologies, Inc.” on page 182 for the location of

these offices. To create a disk set refer to “Creating Software Installation Disks” below.

Creating Software Installation Disks

To create the installation disks on-line, visit the Agilent internet site shown in

“Updating the Firmware” on page 48. Follow the instructions provided on the

internet site for downloading the current measurement personalty software and creating the installation disk set. The instructions for creating the disk set will step you through the process to create a firmware disk set when you create the measurement personalty software disk set. (A firmware update may be needed to ensure that the firmware and the software are compatible.) After you have created the disk set, follow the on-line instructions to install the firmware. After successfully installing the firmware update, proceed with the following instructions for installing the measurement personalty software in your instrument.

Installing Personality/Software Options

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NOTE When the installer starts up, it examines the instrument to ensure that all the

This procedure gives steps to install a new software option in an ESA-E Series Spectrum Analyzer using the internal floppy drive of the instrument. Screen messages display the update progress and give directions. The instrument will not need to be re-calibrated after this procedure since no changes are made to calibration or adjustment files.

If you have a problem with the installation process, refer to “Troubleshooting the

Installer” on page 46.

required software and hardware options are present. If they are not, the installer will generate an error and you will not be able to install the personality.

1. If this is the installation of new personality option software, you must enter the License Key for the new option. For instructions on entering the License Key, refer to the “Installing the Licensing Key” on page 43.

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When you have completed entering the license key number, continue with the next step.

2. Insert disk one of the installation disk set into the disk drive located on the right side of the ESA front panel.

3. Press

4. When the installer first starts up, it will show a popup message. Select

NOTE Once the installer has begun installing a personality, any error will cause the whole

personality (including a previously installed version) to be removed from the instrument. Because of this, it is very important that you verify the disks prior to installing them. If any of the disks or files are bad, you will not be able to use the personality until you obtain a new installation disk set and run the install using them.

5. When prompted, insert the next disk and press

6. When the verification is complete, press

System, More, Personalities,andInstall. The instrument will then load

the installer from the floppy drive. If there is no floppy in the drive, the incorrect disk is inserted, or there is no installer on the disk, the error “No install disk present in disk drive” will be shown.

Once the instrument has loaded the installer, the screen will change to the installer screen and the information on the installer screen and menu, refer to “Installer Screen and

Menu” on page 47.

Disks

When Verify Disks is running, the grayed out.

personality will begin. Some of the disks may take only a short time to load or be skipped entirely, while others can take up to about 30 minutes to load.

Install Pers. menu will be shown. For more

Verify

Ver ify Disks again.

Install Now and Exit Install keys will be

Install Now and the installation of the

Measurements

When installer is running, the out.

7. When prompted, insert the next disk and press

8. Once the installation is complete, press

Chapter 3 45

Verify Disk s and Exit Install keys will be grayed

Install Now again.

Exit Install.

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Troubleshooting the Installer

If the installation process stalls or fails in another way, follow these steps to resolve your problem.

1. If the instrument stops the update process before all the disks are loaded proceed as follows:

a. Press

b. Return to step 2 under “Installing Personality/Software Options” and start

2. If the instrument fails after repeating the installation procedure, get in touch with your nearest Agilent sales and service office listed in “Getting in touch

with Agilent Technologies, Inc.” on page 182 for assistance. Please provide

the following information:

Model Number:

Serial Number:

State that you are having trouble installing a software option update.

Exit Install to abort the process.

the installation process again.

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Installer Screen and Menu

The top portion of the install screen is a table in which the files that are about to be installed are listed. The bottom portion of the screen contains information needed to track the progress of the install.

Table 3-5 Key to Installer Screen and Menu Screen (above)

1 File Table displays the files to be installed and various file information. If there

aremorethensixfiles, view additional items.

2FileNamedisplays the name of the files on the installation disk.

3 Current Version displays the version of the file that is currently installed in the

instrument. (This field will be blank if this file is not currently installed in the instrument or if the file is a data file that has no version.)

4 Upgrade Version shows the version of the file on the install disk. This is the

version of the file that will replace the currently installed version.

5 Status is updated to reflect what the installer is doing to the current file as the

install progress. The valid messages seen in this column are listed in Table 3-6 on

page 48.

6 Data Field contains a status bar and various status information.

7 Processing disk shows the disk that is currently being read.

8 Processing item shows the file that is being processes by item number.

9 Bytes free on C is the number of bytes currently free on the instrument C: drive.

10 Status Bar contains a status bar that runs from 0 to 100% and tracks the progress

of the current step and a message line displays the step that is currently being executed.

Next Item and Prev Item allow you to scroll the table to

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Table 3-5 Key to Installer Screen and Menu Screen (above)

11 B y tes i n package lists the number of bytes in the install package/ fill.

12 Bytes left in package lists the number of bytes left to be read.

13 Message and error popup window that displays over the status bar. Information in

this box will prompt you for action required to proceed to the next phase of the installation. It may also inform you of errors in the installation process and may prompt you for action required to correct the problem.

Table 3-6 Installer Status Messages

Failed This means that something has gone wrong while processing this item. It

is a fatal error and the installation can not be completed. The installer will try to get the system back to a good state which may entail completely removing the currently installed personality.

Loading The file is currently being copied from the install media to the

instrument’s file system.

Verifying This may mean one of two things:

1. If “Verify Disks” was pressed then Verifying means that the installer is currently reading the install media and comparing the known checksums to ensure the data is good.

2. If “Install Now” was pressed, then Verifying means that the installer is reading what was just loaded to ensure the checksum is correct.

Loaded This means that the data has been placed on the instrument disk but has

Installed This means that the data has been loaded into the instrument and

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Skipping This means that the installer has determined that this file does not need

not yet been registered with the firmware.

registered. The install for this file is complete.

to be loaded into the instrument.

Agilent ESA Spectrum Analyzers Update

For the latest information about this instrument, including firmware upgrades, application information, and product information, please visit the URL listed below.

Updating the Firmware

Updated versions of the ESA-E Series Spectrum Analyzer firmware will be available via several sources. Information on the latest firmware revision can be accessed from the following URL:

http://www.agilent.com/find/esa/

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4 Setting Up the Modulation Analysis

Mode

This chapter introduces you to the basic measurement process.

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Preparing to Make Measurements

At initial power up, the analyzer will be in spectrum analyzer (SA) mode and the

FREQUENCY Channel menu displayed. To access the Modulation Analysis

measurement personality, press the

Analysis

key.

Initial Settings

If you have already been into Modulation Analysis mode since the instrument was powered up and you have not performed a preset, then the screen displayed and the

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settings in force will be exactly as they were when you last switched out of Modulation Analysis mode.

When you put the instrument into Modulation Analysis mode for the first time after a power up, the Monitor Spectrum screen will be displayed with a center frequency setting of 1.0 GHz and a span of 6 MHz. This Monitor Spectrum function allows you to check that there is a signal to be measured.

The center frequency can be changed by pressing required frequency using the numeric keys. The span can be altered by pressing

Span and entering the required span using the numeric keys.

Before making a measurement, make sure the mode setup and radio standard parameters are set to the desired settings. Refer to Chapter 6 , “Menu Maps,” and Chapter 7 , “Front Panel Key Reference,” for additional information to guide you in changing parameter settings.

MODE key and select the Modulation

Frequency andthenenteringthe

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You can set the instrument to use under the System front panel key. If you set the preset to Mode or to Factory, pressing Preset causes the analyzer to immediately reset all parameters to that particular setting. Note that a Factory Preset will switch modes, returning the ESA to the Spectrum Analysis mode. You will then have to re-access the Modulation Analysis mode after the preset operation is completed.

If you set the preset to User, the instrument displays a Preset menu when you

Preset.ThePreset menu allows you to select the User defaults, Mode

press defaults or the Factory defaults. For more information on setting, saving, and using user defaults, refer to the ESA Spectrum Analyzers User’s Guide.

If you want to set only the Modulation Analysis mode to a known, factory default state, press Mode Setup and Restore Mode Setup Defaults. This will reset only the Mode parameters to the factory defaults without affecting the SA mode, and the instrument will not exit the Modulation Analysis mode.

To preset only the settings that are specific to the selected measurement, press Restore Meas Defaults under Meas Setup. This will set the measurement setup parameters, for the currently selected measurement only, to the factory defaults.

User preset, Mode preset or Factory preset

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How to Make an EVM (Error Vector Magnitude) Measurement

The EVM (Error Vector Magnitude) measurement is set up and is intended to be used as a “one-button” measurement. After you have properly connected the instrument to the digital communications system equipment and selected the EVM measurement, the measurement is made using the default parameters defined by the selected standard.

You may change the default settings using

Meas Setup key. However, changing

the default settings may produce measurement results that are outside of the parameters of the selected standard.

Most measurements can be performed using the simple four-step procedure outlined in the table below using the keys shown in the figure. Most measurements are performed using only the primary keys listed in conjunction with a minimum of setup keys. Measurement setup keys (

Meas Setup) can be used for

non-standards compliant testing. For more information see “Initial Settings”.

Step Primary Key Setup Keys Related Keys

1. Select and setup mode

2. Select and setup measurement MEASURE Meas Setup,

3. Select and setup view View/Trace Span X Scale,

4. Saving and printing results File

MODE Mode Setup System

Meas Control,

Restore Meas Defaults, FREQUENCY Channel

Amplitude Y Scale

Print Setup Save

, Display

Restart

Marker

, Search

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How to Save Measurement Results

To save measurement results follow the process shown below. For additional information on file management in the spectrum analyzer, refer to the ESA Spectrum Analyzers User’s Guide.

1. Press

2. If you want to change the file name, press

3. The default directory is the C: drive. If you want to change the file directory,

4. Press

5. If you have used the default file name and wish to save additional measurement

6. If you have not used the default file name and wish to save additional

File, Save, Type, More, Measurement Results.

Name, and use the Alpha Editor to

enter the new name. For more information on using the Alpha Editor, refer to the ESA Spectrum Analyzers User’s Guide.

Dir Up (or Dir Select

press directory and then press Dir Select.

Save Now to complete the file saving process.

results, press default file name.

measurement results, repeat steps 1 through 3.

Save. The current measurement result will be saved with the next

)

and use the up or down arrows to select the desired

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5 Making Modulation Analysis

Measurements

This chapter shows how to make modulation analysis measurements and how to interpret them. Various radio signals having different problems are shown and compared against results of acceptable signals.

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What You Will Find in This Chapter

The Modulation Analysis Personality Page 5-55

Purpose Page 5-55

Measurement Method for a CDMA System Page 5-56

Making a CDMA Measurement Page 5-57

Interpreting Measurement Results Page 5-64

Baseband Filtering Errors Page 5-64

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I/Q Gain Imbalance Page 5-69

I/Q Quadrature (Skew) Error Page 5-71

Symbol Rate Error Page 5-74

I/Q DC Offset Error Page 5-77

In-Channel Phase Modulation Interference Page 5-78

In-Channel Amplitude Modulation Interference Page 5-81

In-Channel Spurious Signal Interference Page 5-85

Measuring a Custom QPSK Format Signal Page 5-87

Other Customized Changes You Can Make Page 5-88

Problems Obtaining a Measurement Page 5-89

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The Modulation Analysis Personality

Purpose

A thorough analysis of EVM (error vector magnitude) in a digital communication system is invaluable for troubleshooting common errors such as:

I/Q error Symbol rate errors Wrong filter coefficients Wrong interpolation, IF filter tilt, or ripple LO instability Tone interference AM/PM conversion errors

The Agilent Modulation Analysis Measurement Personality provides this analysis of digitally-modulated signals for the following major cellular standards:

W-CDMA (3GPP) cdmaOne (IS-95 and J-STD-008) cdma2000 SR1 NADC GSM EDGE PDC TETRA

In addition, the personality allows you to alter the filters and symbol rates defined by the communication standards if the signal you are analyzing differs from a defined radio standard.

This guide shows you how to set up the Agilent ESA to measure and display the results of EVM using eye, constellation, and vector diagrams (when measuring appropriate radio standards), as well as tabular data. The key results provided are:

Peak and RMS EVM Peak and RMS Magnitude error Peak and RMS Phase error Frequency error I/Q offset Droop error EVM versus symbol display Magnitude error versus symbol display Phase error versus symbol display Polar vector display Polar constellation display I and Q eye display

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Measurement Method for a CDMA System

Consider making an EVM measurement on a CDMA system.

You can only make an EVM measurement intrusively. When you perform the measurement, a carrier channel with a single pilot channel are the only allowed active channels. No other traffic channels or paging channels may be present.

The intrusive method takes the measurement directly from the RF output port of the transceiver, as shown in Figure 5-1.

CAUTION If you take the measurement directly from the RF output port of the transceiver,

ensure that the power level at the RF input of the spectrum analyzer does not exceed the damage level of 30 dBm.

Because you disconnect the antenna from the transceiver and disrupt the transmission signal, this cannot be considered a non-intrusive test. The transceiver will not be able to communicate with users on the system.

You may also make a less intrusive test by connecting a directional coupler to the RF output with the main arm connected to the antenna and the coupled port connected to the spectrum analyzer, as shown in Figure 5-2.Youmustensurethat only the pilot Walsh channel is active. Because only a pilot channel will be observed, the transceiver will not be able to communicate with users on the system.

NOTE The timebase of the base station and the spectrum analyzer should be locked

together. These are referred to as “10 MHz Ref In” or “Ext Ref In” throughout the remainder of this document.

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Making a Wideband CDMA Measurement

NOTE Use the Help key to get a quick explanation of any Modulation Analysis

Personality key, as well as any equivalent SCPI command that performs the function of that key.

1. Install the Modulation Analysis Measurements Personality as described in the “Getting Started” chapter of this guide.

2. Make sure that the base transceiver station is in service with only the pilot Walsh channel active.

3. Connect the device being measured and the spectrum analyzer input as shown in Figure 5-1 or Figure 5-2.

Figure 5-1 Measurement Setup

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Figure 5-2 Alternative Measurement Setup

4. Press Mode, Modulation Analysis, Mode Setup, Radio Std and choose the radio standard being used.

5. Press

6. Press

FREQUENCY and set the center frequency to the transmit frequency of

the radio.

MEASURE, Monitor Spectrum and check to see that the spectrum looks

reasonable. It should be centered on the display with modulation present, as shown in Figure 5-3 (Wideband CDMA signal shown). If not, then refer to

“Problems Obtaining a Measurement” later in this chapter.

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Figure 5-3 Monitor Spectrum Display

Making Modulation Analysis Measurements

Making a Wideband CDMA Measurement

7. Press

Figure 5-4 Polar Vector Display

8. Press

EVM. You should see an I/Q polar vector display of the signal, similar to

that shown in Figure 5-4. Results are listed in a table left of the vector display.

View/Trace, I/Q Measured Polar Constln. You should see an I/Q polar

constellation display of the signal and the table of critical parameter values, similar to that shown in Figure 5-5.

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NOTE As a troubleshooting tool, you can manually build the polar constellation or step

through the trace with a short line segment using the I/Q Points and I/Q Points

Offset

keys.

Whenyoumakeasinglemeasurement(pressthe the data for that single measurement is held within instrument memory. If you then set the slowly increasing the I/Q Points figure from zero using the RPG knob.

Similarly you can set the the I/Q Points Offset figure using the RPG knob. Now you will see a ‘snake’ marking out the signal’s trace on the display.

I/Q Points Offset to 0, you can see how the measurement is built up by

I/Q Points figure to a low number (say, 5 or 10) and vary

Single key on the front panel),

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Figure 5-5 Polar Constellation Display

9. Press

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I/Q Error (Quad View) and refer to Figure 5-6. You should see graphical

displays of magnitude error versus time, phase error versus time, EVM versus time, and tabular results.

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Figure 5-6 I/Q Errors Showing Magnitude, Phase, and EVM

10. Press

11. Press

12. Change the y-axis scaling (% for EVM, Magnitude, and ° for Phase Error

13. The blue data points shown along the traces are the symbol decision point

Next Window (a key located below the display). Each of the four

individual windows are “highlighted” by a colored border as you press this key. Press

Next Window again and then press Zoom. The size of the selected

window expands for easier viewing.

Next Window to select one of the time graphs and then press Zoom.

Change the x-axis scaling (number of symbols) to 2/division by pressing

SPAN, Scale/Div, 2, Sym. This menu also allows you to change the x-axis

reference value and position.

graphs) to 0.5/division by pressing menu also allows you to change the y-axis reference value and position.

locations. To turn these off, press menu also allows you to change I/Q points and points/symbol. Press return to normal viewing.

AMPLITUDE, Scale/Div, .5, % (or °.) This

Display, Symbol Dots Quad View, Off.This

Zoom to

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14.Press View/Trace, Eye (Quad View) and refer to Figure 5-7. You should see individual eye diagrams for I and Q, along with a polar vector display, and tabular results of critical parameter values.

NOTE As a troubleshooting tool, you can manually build the polar constellation or step

through the trace with a short line segment using the

Offset

keys.

I/Q Points and I/Q Points

Whenyoumakeasinglemeasurement(pressthe the data for that single measurement is held within instrument memory. If you then set the I/Q Points Offset to 0, you can see how the measurement is built up by slowly increasing the

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Figure 5-7 Eye Diagrams with Polar Vector Constellation

Similarly you can set the the

I/Q Points Offset figure using the RPG knob. Now you will see a ‘snake’

marking out the signal’s trace on the display.

I/Q Points figure from zero using the RPG knob.

I/Q Points figure to a low number (say, 5 or 10) and vary

Single key on the front panel),

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15. Press Numeric Results and refer to Figure 5-8. You should see a tabular display of the critical parameter values similar to the tables in the previous views. This table differs in that it also includes peak values for magnitude error and phase error. The specific symbols are identified with each of these values.

Figure 5-8 Numeric Results View

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The power of the Modulation Analysis Personality is its ability to characterize the radio signal for transmitter troubleshooting. This section illustrates how to interpret the data to indicate symptoms of problems in radio signals.

The following radio signal errors are investigated in this section:

Baseband Filtering Errors I/Q Gain Imbalance I/Q Quadrature (Skew) Error I/Q DC Offset Error

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Symbol Rate Error I/Q DC Offset Error In-Channel Phase Modulation Interference In-Channel Amplitude Modulation Interference In-Channel Spurious Signal Interference

Baseband Filtering Errors

Filtering errors are among the most common in digital communication design. Typical filter errors can be due to errors in filter alpha, wrong filter shape, or incorrect filter coefficients. The result is increased intersymbol interference. Lower peak overshoot is also caused by signal compression, which can indicate that an amplifier stage is being overdriven.

1. The vector diagram gives the first indication of baseband filtering errors. Press

I/Q Measured Polar Vector. The display should look similar to that shown in

Figure 5-9 Polar Vector of Signal Using a 0.22 Filter α

Figure 5-9. This is a normal Wideband CDMA signal shown with a filter α of

0.22.

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2. In contrast, refer to Figure 5-10. A Wideband CDMA signal is shown with a filter α of 1. Observe that there are smaller overshoots in the trajectories between the symbol points (item 1) due to the increased alpha. This limits the required peak power and reduces the transmitter power requirements. Item 2 shows spreading of the decision points due to the increased EVM (item 3.)

NOTE To change the filter α of the analyzer, press Det/Demod, Alpha/BT.

Figure 5-10 Polar Vector of Signal Using a 1.0 Filter α

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3. Press View/Trace, Eye (Quad View), Next Window, Next Window, Next

Window, Zoom

(W-CDMA signal shown with filter α = 0.22.)

Figure 5-11 I Eye Diagram of Signal Using a 0.22 Filter α

. The display should look similar to that shown in Figure 5-11

4. In contrast, refer to Figure 5-12. This shows a Wideband CDMA signal with a filter α of 1 (item 2). An incorrect filter alpha is indicated when the center diamond shape is distorted with rounding and widened crossover points at the top and bottom corners (item 1.) The eye diagram tends to “spread out” in this case.

Figure 5-12 I Eye Diagram of Signal Using a 1.0 Filter α

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5. Press View/Trace, I/Q Error (Quad View).PressNext Window until the EVM graph is highlighted. Press Zoom,Amplitude,Scale/Div,6,%to expand the y-axis scale. Press SPAN, Scale/Div, 1, Sym to expand the x-axis scale. The result of a “normal” signal is shown in Figure 5-13 (W-CDMA signal shown with filter α = 0.22.)

Figure 5-13 Zoomed EVM Display of Signal Using a 0.22 Filter α

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6. In contrast, refer to Figure 5-14 (W-CDMA signal shown with filter α=1.)

Differing filter alphas between the transmitter and receiver do not significantly affect the symbol locations. However, differing alphas do cause incorrect transitions. As a result, the error vector is large between symbol points and relatively small at the symbol locations (item 1.)

Figure 5-14 Zoomed EVM Display of Signal Using a 1.0 Filter α

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I/Q Gain Imbalance

I/Q gain imbalance is a result of non-equal gains in the I and Q parts of the network. This can be caused by differences in components such as filters, amplifiers, and DACs. For non-scrambled or spread QPSK signals, the symptom of this imbalance is indicated by rectangular-shaped groupings of symbol decision points in each quadrant.

Press

Meas Control, Pause to view a single time record.

1. Use the I/Q polar constellation diagram first to identify this problem. Press

View/Trace, I/Q Measured Polar Constln. A signal with an I/Q gain

imbalance is shown in Figure 5-15. A rectangular shape is indicated with the symbol decision points at the rectangle corners, instead of the square shape you would normally see with a properly balanced signal. A gain imbalance of 2 dB was used to obtain this result.

NOTE The long side of the rectangle appears along the I axis, but this will shift 90° along

the Q axis and back again in random fashion. This is normal.

The analyzer arbitrarily assigns the demodulated symbols to the I and Q channels for each new time record; the analyzer acts as an asynchronous receiver. For this reason, it is not possible to determine the correct carrier phase reference.

Although the display indicates a Wideband CDMA format, the signal shown is a non-scrambled or spread QPSK signal.

Figure 5-15 Polar Constellation Showing an I/Q Gain Imbalance

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2. The polar vector diagram is shown in Figure 5-16. Observe that the rectangular shape has shifted by 90°, with the longer side of the rectangle along the Q axis. As stated earlier, this is normal, and will arbitrarily shift back and forth.

Figure 5-16 Polar Vector Showing an I/Q Gain Imbalance

3. Figure 5-17 shows the same signal using the eye diagram. Observe that with a gain imbalance, the I and Q eye diagrams will not be similar in shape, and these shapes will be swapped back and forth between each other. In this figure, the Q eye diagram vertical amplitude (item 1) is greater than that of the I eye diagram (item 2.)

Figure 5-17 Eye Diagram Showing an I/Q Gain Imbalance

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I/Q Quadrature (Skew) Error

Quadrature error is due to lack of a 90 degree phase shift between the I and Q channels of a transmitter.

For non-scrambled or spread QPSK signals, the symptom of quadrature error is indicated by parallelogram-shaped groupings of symbol decision points in each quadrant.

Press

Meas Control, Pause to view a single time record.

1. Use the I/Q polar constellation diagram first to identify this problem. Press

Measured Polar Constln

Figure 5-18. A parallelogram shape is indicated with the symbol decision

points at the rectangle corners. A quadrature difference of 10° was used to obtain this result.

Figure 5-18 Polar Constellation Showing I/Q Quadrature Error

. A signal with an I/Q quadrature error is shown in

I/Q

Measurements

NOTE The shape of the parallelogram will shift 90° along the two axes and back again in

random fashion. This is normal.

Although the display indicates a Wideband CDMA format, the signal shown is a non-scrambled or spread QPSK signal.

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2. The polar vector diagram is shown in Figure 5-19.Observethatthe parallelogram shape has shifted by 90°. As stated earlier, this is normal, and will arbitrarily shift back and forth.

Figure 5-19 Polar Vector Showing I/Q Quadrature Error

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3. The zoomed I eye diagram is shown in Figure 5-20. Observe that with a quadrature error, the crossover points alternately shift between time records. Because of this, an open triangle pattern begins to take shape at the decision points (item 1.)

Figure 5-20 Zoomed I Eye Diagram Showing I/Q Quadrature Error

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Symbol Rate Error

Small deviations in the symbol clock can result in significant modulation errors. Even a small error in symbol rate causes a large increase in peak EVM, and is indicated by a spreading of the symbol decision points.

Large symbol rate errors will result in the receiver not being able to demodulate the signal. The Modulation Analysis Personality is most useful in troubleshooting small symbol rate errors. To troubleshoot circuits with large symbol rate errors, try using the ESA occupied bandwidth measurement function to view the signal channel bandwidth. You can roughly approximate the symbol rate using this method.

1. Use the I/Q polar constellation diagram first to identify symbol rate errors.

I/Q Measured Polar Constln. A signal with symbol rate errors is shown

Press in Figure 5-21. Note the spreading of the symbol decision points and large values of EVM. A symbol rate error of 0.0015 Msps over the actual symbol rate was used to obtain this result.

Figure 5-21 Polar Constellation Showing Symbol Rate Error

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2. Figure 5-22 shows the polar vector diagram of this signal, with a received symbol rate of 3.84150 Msps (this symbol rate can be seen above the vector diagram in the figure.) The transmitted symbol rate is 3.840 Msps.

Figure 5-22 Polar Vector Showing Symbol Rate Error

Interpreting Measurement Results

3. Figure 5-23 shows the I/Q error views of this signal. Observe at item 1 that with a symbol rate error, the EVM versus time graph shows a “V” shape.

Figure 5-23 I/Q Error Diagram Showing Symbol Rate Error

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4. Figure 5-24 shows the EVM versus time graph in zoom mode. The characteristic “V” shape is caused by the demodulator aligning the expected symbol clock rate with the clock rate of the signal, for best fit at the midpoint of the trace. The differences in the two clocks show increasing “slip,” or deviation further from the trace center. At one arbitrary reference sample, the signal is sampled correctly. But since the symbol rate is skewed, any other sample in the positive or negative direction is slightly off in time. This causes an error which increases linearly in time.

Figure 5-24 Zoomed EVM Versus Symbol Display Showing Symbol Rate Error

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I/Q DC Offset Error

DC offset is characteristic of an improperly adjusted balanced modulator. Typically, these offsets are added in the amplifier in the I and Q paths. This type of error should be indicated in a displaced constellation from the origin of the I/Q plane. However, any DC offset is reported in the summary/symbol table only, since the analyzer measures and removes this offset during demodulation.

1. Use the I/Q polar constellation diagram to identify I/Q DC offset errors. Press

I/Q Measured Polar Vector. A signal with an I/Q DC offset error is shown in

Figure 5-25. Observe that there are no noticeable errors shown in the vector

diagram itself. However, the I/Q offset value in the table is about –28 dBc (item 1), and should be closer to –52 dBc for a Wideband CDMA signal.

Figure 5-25 Polar Vector Showing I/Q DC Offset Error

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In-Channel Phase Modulating Interference

Many signals are present in an integrated communications system. Examples may include digital, baseband, IF, and RF signals. Crosstalk between adjacent components and stages often leads to unwanted signals in the output. The Modulation Analysis Personality can help identify these signals, including in-channel phase modulating signals.

For a Wideband CDMA signal, PM interference appears as an aligning of the symbol decision points in the center of each quadrant, forming “lines” of dots. This line extends farther outward as the magnitude of the PM increases.

1. Use the I/Q polar constellation diagram first to identify this problem. Press

Measured Polar Constln

CDMA signal with in-channel phase modulation interference. Note the variation of phase around the ideal symbol reference points. Also observe how much larger the phase error values are compared to those for magnitude error in the table.

The results shown were created with a phase modulation deviation of 0.03 pi radians (about 5.5°) and a modulating frequency of 45 kHz.

Figure 5-26 Polar Constellation Showing PM Interference

. Figure 5-26 shows an example of a Wideband

I/Q

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2. The I/Q error views are shown in Figure 5-27. Observe that the sinusoidal modulating waveform of the interfering PM signal is shown in the phase error versus time graph. If the graphical result was random, it would have indicated phase noise and not a PM interfering signal.

Figure 5-27 I/Q Error Display Showing PM Interference

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3. The zoomed phase error graph is shown in Figure 5-28. If the number of cycles can be accurately determined, the phase modulating signal frequency can be calculated. Use the necessary, to make this determination. It may also be helpful to pause the trace using the

In this example, Phase Error freq. = 3 cycles, number of symbols = 256, and

symbol rate is 3.84 x 10

PMf=3/256x3.84x106,or45kHz

Meas Control key.

= Phase Error freq. / number of symbols x symbol rate

Span and Amplitude keys to adjust the scaling, if

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Figure 5-28 Zoomed Phase Error Display Showing PM Interference

4. Peak deviation of the phase modulating signal is easily determined from Figure

5-28. There are about 5 divisions of peak phase modulation at 1 degree per

division. This approximates the actual 5.5° of phase modulation applied to create this signal.

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Interpreting Measurement Results

In-Channel Amplitude Modulation Interference

For a Wideband CDMA signal, AM interference appears as an aligning of the symbol decision points in the center of each quadrant, forming “lines” of dots. This line extends farther outward as the magnitude of the AM increases.

1. Use the I/Q polar constellation diagram first to identify this problem. Press

Measured Polar Constln

CDMA signal with in-channel amplitude modulation interference. Note the variation of amplitude around the ideal symbol reference points. Also observe how much larger the amplitude error values are compared to those for phase error in the table.

The results shown were created with an amplitude modulation depth of 10% andamodulatingfrequencyof15kHz.

Figure 5-29 Polar Constellation Showing AM Interference

. Figure 5-29 shows an example of a Wideband

I/Q

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2. The I/Q error view graphs are shown in Figure 5-30.

Figure 5-30 I/Q Error Display Showing AM Interference

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Interpreting Measurement Results

3. The zoomed phase error graph is shown in Figure 5-31. If the number of cycles can be accurately determined, the amplitude modulating signal frequency can be calculated. Use the necessary, to make this determination. It may also be helpful to pause the trace using the

In this example, Phase Error freq. = 1.1 cycles, number of symbols = 256, and

symbol rate is 3.84 x 10

AMf= 1.1/256 x 3.84 x 106, or about 16 kHz

Figure 5-31 Zoomed Phase Error Display Showing AM Interference

Meas Control key.

= Phase Error freq. / number of symbols x symbol rate

Span and Amplitude keys to adjust the scaling, if

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4. Peak deviation of the amplitude modulating signal is easily determined from

Figure 5-32, the zoomed magnitude error versus time graph. There are about 7

divisions of peak-to-peak amplitude modulation at 3% per division, yielding

10.5% peak amplitude. This approximates the actual 10% of amplitude modulation applied to create this signal.

Figure 5-32 Zoomed Magnitude Error Display Showing AM Interference

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Interpreting Measurement Results

In-Channel Spurious Signal Interference

For a Wideband CDMA signal, an in-channel spurious signal appears as ring-shaped groupings of symbol decision points in each of the quadrants. This is because the spur modulates both the amplitude and phase of the I and Q signals. The ring diameter increases as the magnitude of the spur increases. If the signal is modulated without spurious interference, the clusters of symbol decision points in each quadrant will form a solid spot rather than a ring.

1. Figure 5-33 shows an in-channel spurious signal that is –15 dBc and + 400 kHz away from the unmodulated radio signal. Even a large interfering signal such as this is barely visible in the spectrum view, even with averaging on.

Figure 5-33 Spectrum Display Showing In-Channel Spurious Interference

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2. Use the I/Q polar constellation diagram first to identify this problem. Press I/Q

Measured Polar Constln

same interfering signal as was used in Figure 5-33.

Figure 5-34 Polar Constellation Showing Spurious Interference at –15 dBc

. Figure 5-34 shows the results created using the

3. The same view of the interfering signal is shown in Figure 5-35, but at –28 dBc. The characteristic ring shape can still be seen.

Figure 5-35 Polar Constellation Showing Spurious Interference at –28 dBc

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Measuring a Custom QPSK Format Signal

The Modulation Analysis Personality allows you to demodulate a QPSK modulation formatted signal using your own custom parameters. This section provides an example of how to set up the analyzer to measure such a signal. The signal parameters are: type QPSK modulation, symbol rate 3.84 Msps, Root Nyquist filtering using Alpha/BT of 0.35.

1. Press

2. Press

3. Press

4. Press

5. Press

6. Press

You should see the classic four symmetric decision regions (symbol points) of a QPSK constellation, as shown in Figure 5-36.

Figure 5-36 Polar Constellation of a QPSK Signal

Demod Format, QPSK to select the correct demodulation format.

Symbol Rate, 3.84 Msps to enter the correct symbol rate.

Meas Filter, Root Nyquist to select the correct measurement filter.

Ref Filter, Nyquist to select the correct reference filter.

Det/Demod, Alpha/BT, 0.35, Enter to enter the correct alpha value.

View/Trace, I/Q Measured Polar Constln to select the correct

constellation view.

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Other Customized Changes You Can Make

1. Press Display to vary the number of I/Q points, I/Q points offset, and turn on or off the symbol dots for polar vector or quad views.

2. Press

3. Set the measurement parameters to the default values by pressing

NOTE If the desired RF channel or channel frequency has been set for a previous

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measurement, it is used for all subsequent measurements, and it does not need to be set again.

4. Set the mode parameters to the default values by pressing

5. To change any of the measurement parameters from the factory default values,

Det/Demod to access a menu to allow you to vary the type of

measurement and reference filters.

Meas Setup,

More, Restore Meas Defaults

Restore Mode Setup Defaults

press the allow you to modify the parameters for this measurement. For additional information on keys to access measurement parameters, refer to the Front Panel Key Reference section in this User’s Guide, or use the on-screen help.

Meas Setup, Mode Setup,orDet/Demod keys to access menus that

Mode Setup,

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Problems Obtaining a Measurement

The following list of common problems and their solutions may help if you are having trouble obtaining a proper measurement using the Modulation Analysis Personality.

In Monitor Spectrum mode, the signal is missing, or does not look correct

• The analyzer may be tuned to a frequency other than the radio signal frequency. While the analyzer is in Modulation Analysis mode, press FREQUENCY

Channel

while in SA mode, the Modulation Analysis mode frequency was unaffected.

When using the GSM or EDGE standards, the spectrum looks valid, but all EVM measurements are invalid

and then set the analyzer frequency. If the analyzer frequency was set

If you are using a signal generator, the data format must be “framed” and not “patterned,” unlike the other TDMA modes. For example, the signal needs to be bursted with the correct midamble training sequence code as is defined in the GSM or EDGE standard. The spectrum should look like Figure 5-37 for both GSM and EDGE signals with only one active timeslot.

Figure 5-37 Spectrum Display of an EDGE Signal with One Active Timeslot

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An NADC, TETRA, or PDC signal looks incorrect

Make sure that BTS/MS is correctly selected. BTS assumes a continuous, non-burst signal with all timeslots active.

If your NADC, TETRA or PDC BTS signal is bursted, all inactive timeslots are transmitted as a series of the numeral 1. If fewer than six down channels (or four for TETRA) are active, one or more of the down channels will be transmitting all ones and the EVM results will be inaccurate. If all six down channels (or all four in the case of TETRA) are active, this is detected as a continuous signal and can be demodulated. The demodulate a continuous signal.

If your NADC or PDC MS signal has two adjacent active timeslots, the signal will be demodulated as one timeslot centered on the adjoining edges of the two timeslots, and again the results will be inaccurate.

To alleviate the problems described above, there are several possible workarounds. These include:

• Test your BTS signals with all timeslots active.

• Artificially create a pulse envelope by adjusting the amplitude of the timeslot of interest.

RF Amptd parameter of Burst Sync needs to be set to None to

• Use an external trigger with timeslots of interest.

External Trigger Delay to manually align the

A “Wideband Cal Required” error message appears

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•PressDet/Demod, More 1 of 2, Wideband Cal. Follow any instructions given on the display and then continue the measurement. Once the calibration has been completed, the analyzer will return to the previous measurement screen.

Wideband Cal allows you to perform a factory calibration of the modulation

analysis software. As the analyzer is calibrated on leaving the factory, this only has to be done after installing new software. Calibration is best done after the analyzer has reached its normal operating temperature. When the internal temperature changes, a partial calibration is automatically carried out and is indicated on the screen.

If a Wideband Cal is done when the analyzer has reached its normal operating temperature, the number of automatic cals will be reduced. If the ESA has not been aligned, a full Alignment is done before the Wideband Cal. Calibration is complete once the analyzer returns to its previous screen. A Wideband Cal on its own should take about 90 secs; a Wideband Cal with Alignment takes up to 10 mins.

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The results show a large EVM

• Make sure that the instrument reference is correct. Check if an external reference is being used by pressing Det/Demod, More 1 of 2.Alsochecktosee that a cable is connected between the 10 MHz OUT port of the RF Communications Hardware (Option B7E) board to the ESA 10 MHz REF IN port.

• When using an external reference signal, there is a possibility of significant degradation in some EVM measurement results. This is more likely to be a problem if your EVM measurements are being made on signals with low symbol rates, such as TETRA, NADC or PDC. If your external reference signal can be set to 10 MHz, connect it directly into the 10 MHz REF IN port to alleviate this problem.

• If you are measuring a bursted signal, go to the the burst edges are not being used in the EVM measurement. If you can see the burst edges, you can either change the input signal properties or reduce the

Meas Interval under the Meas Setup key.

I/Q Error view and ensure that

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6 Menu Maps

This chapter provides a visual representation of the front-panel keys and their associated menu keys. Refer to Chapter 7 , “Front Panel Key Reference,” for key function descriptions.

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What You Will Find in This Chapter

This chapter provides menu maps for the front panel keys having associated menus. The key menus appear in alphabetical order as follows:

AMPLITUDE Y Scale Page 6-95

Det/Demod Page 6-96

Display Page 6-97

FREQUENCY Channel Page 6-98

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Installer Page 6-99

MEASURE Page 6-100

Measurement Setup—Monitor Spectrum Page 6-101

Measurement Setup—EVM Page 6-102

MODE Page 6-103

Mode Setup Page 6-104

SPAN X Scale Page 6-105

Tri g Page 6-106

View/Trace Page 6-107

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Amplitude Menu

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Menus

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Menus

Installer Menus

For more information on the System and Personalities menus, refer to the ESA Spectrum Analyzers User’s Guide.

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Agilent E4402B User’s, Programming, and Measurement Guide

Specifications and Main Features

Frequently Asked Questions

User Manual

1 Using This Document

Book Organization

2 Understanding Modulation Analysis

Digital Communication Systems Standards Overview

The cdmaOne (IS-95) Communication System

The W-CDMA Communication System

The CDMA2000 Communication System

W-CDMA and cdma2000 Advantages

cdmaOne Standards

The NADC Communications System

The GSM Standards

The EDGE Standard

The PDC Standard

The TETRA Standard

What the Modulation Analysis Measurement Personality Does

Other Sources of Measurement Information

3 Getting Started

Instrument Overview

Front-Panel Features

Rear-Panel Features

Options Required

Installing Optional Measurement Personalities

Active License Key

Installing the Licensing Key

Using the Install Key

Installer Screen and Menu

Agilent ESA Spectrum Analyzers Update

Preparing to Make Measurements

Initial Settings

How to Make an EVM (Error Vector Magnitude) Measurement

How to Save Measurement Results

What You Will Find in This Chapter

The Modulation Analysis Personality

Purpose

Measurement Method for a CDMA System

Making a Wideband CDMA Measurement

Interpreting Measurement Results

Baseband Filtering Errors

I/Q Gain Imbalance

I/Q Quadrature (Skew) Error

Symbol Rate Error

I/Q DC Offset Error

In-Channel Phase Modulating Interference

In-Channel Amplitude Modulation Interference

In-Channel Spurious Signal Interference

Measuring a Custom QPSK Format Signal

Other Customized Changes You Can Make

Problems Obtaining a Measurement

In Monitor Spectrum mode, the signal is missing, or does not look correct

When using the GSM or EDGE standards, the spectrum looks valid, but all EVM measurements are invalid

An NADC, TETRA, or PDC signal looks incorrect

A “Wideband Cal Required” error message appears

The results show a large EVM

6 Menu Maps

What You Will Find in This Chapter

Menus

Amplitude Menu

Det/Demod Menus

Display Menus

Frequency/Channel Menu

Installer Menus

Measure Menu