Agilent E4445A Flexible Digital Modulation Analysis Guide

Flexible Digital Modulation Analysis

Guide

PSA Series Spectrum Analyzers

Option 241

This manual provides documentation for the following instruments:

Spectrum Analyzers: E4440A (3 Hz – 26.50 GHz) E4443A (3 Hz – 6.70 GHz) E4445A (3 Hz – 13.20 GHz) E4446A (3 Hz – 44.00 GHz) E4447A (3 Hz – 42.98 GHz) E4448A (3 Hz – 50.00 GHz)

Manufacturing Part Number: E4440-90620

Supersedes E4440-90351

Printed in USA

June 2008

Notice

Agilent Technologies makes no warranty of any kind with regard to this material, including but not limited to, the implied warranties of merchantability and fitness for a particular purpose. Agilent Technologies shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing, performance, or use of this material.

The information contained in this document is subject to change without notice.

Additional Information

For the latest information about this analyzer, including firmware upgrades, application information, and product information, see the following URL:

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

Contents

1. Introduction

What Does the Agilent PSA Option 241 Do? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Installing Optional Measurement Personalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Do You Have Enough Memory to Load All Your Personality Options? . . . . . . . . . . . . . . . . 18

How to Predict Your Memory Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Loading an Optional Measurement Personality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Obtaining and Installing a License Key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Viewing a License Key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Using the Delete License Key on PSA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Ordering Optional Measurement Personalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

2. Making Measurements

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Setting Up the Test Equipment and DUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Making the Initial Signal Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Configuring a MS Measurement System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Configuring a BTS Measurement System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Using Instrument Presets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Determining the RF Parameters of Your Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Using the Spectrum Measurement to View the RF Parameters of the Signal Under Test 31

Spectrum (Frequency Domain) Measurements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Using the Waveform Measurement to Set Up Triggering (for burst signals) . . . . . . . . . . . 41

Waveform (Time Domain) Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Modulation Analysis Measurements in 8 Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Modulation Analysis Measurement Final Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Modifying Measurement Setup Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Using the Measurement Setup Form. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Setting Demodulation Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Setting up a Trigger Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Setting Burst/Sync Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Using Adaptive Equalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Setting Advanced Measurement Setup Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Measuring Digital Modulation Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Setting up the Modulation Analysis Personality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Viewing the I/Q Polar Vector and Constellation Graphs . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Viewing the Numeric Measurement Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Viewing the I/Q Error (Quad-View) Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Viewing the Magnitude Error Versus Time Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Viewing the Phase Error Versus Time Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Viewing the EVM Versus Time Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

Viewing the Eye Diagram Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Viewing the FSK Error (Quad-View) Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Viewing the FSK Error Versus Time Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Viewing the FSK Error Spectrum Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Viewing the FSK Measured Time Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

PSK Modulation Analysis (cdma2000 QPSK Example) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

QAM Modulation Analysis (64QAM Example) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

EDGE Modulation Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

FSK Modulation Analysis (Bluetooth 2FSK Example). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

Contents

Table of Contents

3. Front-Panel Key and SCPI Command Reference

MSK Modulation Analysis (GSM MSK type 1 Example). . . . . . . . . . . . . . . . . . . . . . . . . . . .93

Analyzing and Troubleshooting Digital Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95

EVM Troubleshooting Procedure Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95

Measurement 1 - Obtaining EVM Results with Phase Error and Magnitude Error . . . . . .96

Measurement 2 - Phase Error vs. Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .97

Measurement 3 - Magnitude Error vs. Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98

Measurement 4 - I/Q Constellation Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99

Measurement 5 - Error Vector Magnitude vs. Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101

Interpreting Measurement Results (Impairments) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .102

SCPI Programming a Modulation Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

Interpreting Error Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .119

Instrument Front Panel Highlights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122

Selected PSA Front-Panel Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .123

Front-Panel Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .124

Det/Demod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .124

FREQUENCY Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .124

Input/Output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .126

Meas Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129

MEASURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .130

Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .130

Instrument Selection by Name (Remote command only). . . . . . . . . . . . . . . . . . . . . . . . . . .131

Instrument Selection by Number (Remote command only) . . . . . . . . . . . . . . . . . . . . . . . . .131

Mode Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .131

Trig . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133

Modulation Analysis Measurement Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .141

AMPLITUDE Y Scale. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .141

Y Scale / Div . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .142

Y Ref Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .143

Y Ref Position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .143

Y Scale Coupling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .144

Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .144

Markers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .148

Meas Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150

SPAN X Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .176

Trace/View. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .179

SCPI only operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .180

Trig Error Offset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .180

SCPI Result Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .180

Averaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .187

4. Concepts

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .190

Introduction to Digital Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .191

Why Choose Digital Instead of Analog Modulation? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .191

What is Digital Modulation? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .191

PSK examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .194

Contents

Orthogonality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195

QAM example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195

Symbol Rate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196

Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196

Filtering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197

Effects Of Going Through The Origin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199

Transmitting the Digital Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200

I/Q Modulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200

System Multiplexing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201

Digital Modulation Format Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203

Modulation Formats and Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203

Families of Format and data sheets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203

Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204

Phase Shift Keying (PSK) Concepts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205

Frequency Shift Keying (FSK) Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215

Minimum Shift Keying (MSK) Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218

Quadrature Amplitude Modulation (QAM) Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221

Modulation Bit State Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224

Communication System Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238

PSA option 241 Communications Format Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238

What is the cdmaOne (IS-95) Communication System? . . . . . . . . . . . . . . . . . . . . . . . . . . . 239

cdmaOne Communication System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241

What is the W-CDMA Communications System? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242

W-CDMA Communication System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246

What Is the cdma2000 Communication System? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247

cdma2000 Communication System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250

What is the NADC Communications System? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251

NADC Communication System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254

What is the PDC Communications System? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255

PDC Communication System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256

What is the PHS Communication System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257

PHS Communication System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258

What is the TETRA Communications System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259

TETRA Communication System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261

What is Bluetooth? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262

Bluetooth Communication System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265

What are GSM and EDGE? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266

EDGE Communication System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270

What is APCO25 phase 1? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271

APCO25 phase1 Communication System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275

What is VDL Mode 3? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276

What is ZigBee (IEEE 802.15.4)? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277

Measurements on Digital RF Communications Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . 278

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278

Digital Modulation Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278

Measurement Domains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279

PSA Digital Demodulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281

Modulation quality measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286

Table of Contents

Contents

Table of Contents

5. Menu Maps

Digital Modulation Errors and Signal Impairments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .292

Impairments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .295

Digital Modulation Displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .300

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .308

Other Sources of Digital Modulation Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .308

Flexible Digital Modulation Analysis Key Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .310

Directions for Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311

List of Commands

|FMEAsured|DBITs|RFSPectrum|ARFSpectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150

:CALCulate:<measurement>:MARKer[1]|2|3|4:TRACe? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150

:CALCulate:EVM:LIMit:FERRor <frequency> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

:CALCulate:EVM:LIMit:FERRor:STATe ON|OFF|1|0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

:CALCulate:EVM:LIMit:FERRor:STATe? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

:CALCulate:EVM:LIMit:FERRor? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

:CALCulate:EVM:LIMit:RMS <real> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

:CALCulate:EVM:LIMit:RMS:STATe ON|OFF|1|0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

:CALCulate:EVM:LIMit:RMS:STATe?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

:CALCulate:EVM:LIMit:RMS? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

:CALCulate:EVM:MARKer[1]|2|3|4:FUNCtion BPOWer|NOISe|OFF . . . . . . . . . . . . . . . . . . . 149

:CALCulate:EVM:MARKer[1]|2|3|4:FUNCtion? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149

:CALCulate:EVM:MARKer[1]|2|3|4[:STATe] OFF|ON|0|1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150

:CONFigure:EVM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180

:DISPlay:EVM:FVECtor[:STATe] OFF|ON|0|1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

:DISPlay:EVM:FVECtor[:STATe]? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

:DISPlay:EVM:IQPoints <integer> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

:DISPlay:EVM:IQPoints:OFFSet <integer> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

:DISPlay:EVM:IQPoints:OFFSet? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

:DISPlay:EVM:IQPoints? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

List of Commands

:DISPlay:EVM:IQPType VCONstln|VECTor|CONStln . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146

:DISPlay:EVM:IQPType? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146

:DISPlay:EVM:IQRotation <degree> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

:DISPlay:EVM:IQRotation:STATe ON|OFF|1|0. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

:DISPlay:EVM:IQRotation:STATe? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

:DISPlay:EVM:IQRotation? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

:DISPlay:EVM:PPSYmbol ONE|TWO|FOUR|FIVE|TEN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146

:DISPlay:EVM:PPSYmbol? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146

:DISPlay:EVM:VIEW POLar|IQERror|EYE|FSKError|NRESults

List of Commands

|DBITs|EVSPectum|EQUalizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .179

:DISPlay:EVM:VIEW? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .179

:DISPlay:EVM[1]|2|3|4|5|6|7|8:WINDow[1]|2|3|4:TRACe:

X[:SCALe]:COUPle OFF|ON|0|1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .178

:DISPlay:EVM[1]|2|3|4|5|6|7|8:WINDow[1]|2|3|4:TRACe:X[:SCALe]:COUPle? . . . . . . . . . .178

:DISPlay:EVM[1]|2|3|4|5|6|7|8:WINDow[1]|2|3|4:

TRACe:X[:SCALe]:PDIVision <real> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .177

:DISPlay:EVM[1]|2|3|4|5|6|7|8:WINDow[1]|2|3|4:TRACe:X[:SCALe]:PDIVision? . . . . . . . .177

:DISPlay:EVM[1]|2|3|4|5|6|7|8:WINDow[1]|2|3|4:TRACe:X[:SCALe]:RLEVel <real> . . . . .177

:DISPlay:EVM[1]|2|3|4|5|6|7|8:WINDow[1]|2|3|4:TRACe:X[:SCALe]:RLEVel? . . . . . . . . . .177

:DISPlay:EVM[1]|2|3|4|5|6|7|8:WINDow[1]|2|3|4:

TRACe:X[:SCALe]:RPOSition LEFT|CENTer|RIGHt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .178

:DISPlay:EVM[1]|2|3|4|5|6|7|8:WINDow[1]|2|3|4:TRACe:X[:SCALe]:RPOSition? . . . . . . . .178

:DISPlay:EVM[1]|2|3|4|5|6|7|8:WINDow[1]|2|3|4:TRACe:

Y[:SCALe]:COUPle 0|1|OFF|ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .144

:DISPlay:EVM[1]|2|3|4|5|6|7|8:WINDow[1]|2|3|4:TRACe:Y[:SCALe]:COUPle? . . . . . . . . . .144

:DISPlay:EVM[1]|2|3|4|5|6|7|8:WINDow[1]|2|3|4:TRACe:Y[:SCALe]:PDIVision <real> . . .142

:DISPlay:EVM[1]|2|3|4|5|6|7|8:WINDow[1]|2|3|4:TRACe:Y[:SCALe]:PDIVision? . . . . . . . .142

:DISPlay:EVM[1]|2|3|4|5|6|7|8:WINDow[1]|2|3|4:TRACe:Y[:SCALe]:RLEVel <real> . . . . .143

:DISPlay:EVM[1]|2|3|4|5|6|7|8:WINDow[1]|2|3|4:TRACe:Y[:SCALe]:RLEVel? . . . . . . . . . .143

:DISPlay:EVM[1]|2|3|4|5|6|7|8:WINDow[1]|2|3|4:TRACe:

Y[:SCALe]:RPOSition TOP|CENTer|BOTTom. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .143

:DISPlay:EVM[1]|2|3|4|5|6|7|8:WINDow[1]|2|3|4:TRACe:Y[:SCALe]:

RPOSition? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .143

:FETCh:EVM[n]? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .180

:INITiate:CONTinuous OFF|ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129

:INITiate:EVM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .180

:INITiate:PAUSe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .130

:INITiate:RESTart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129

:INITiate:RESume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .130

:INSTrument:NSELect 241 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .131

:INSTrument:NSELect?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .131

:INSTrument[:SELect] SA|BASIC|DMODULATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .131

List of Commands

:INSTrument[:SELect]? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

:MEASure:EVM[n]? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180

:READ:EVM[n]? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180

:TRIGger[:SEQuence]:AUTO:STATe ON|OFF|1|0. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

:TRIGger[:SEQuence]:AUTO:STATe? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

:TRIGger[:SEQuence]:AUTO[:TIME] <time> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

:TRIGger[:SEQuence]:AUTO[:TIME]?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

:TRIGger[:SEQuence]:EXTernal[1]|2:DELay <time> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136

:TRIGger[:SEQuence]:EXTernal[1]|2:DELay? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136

:TRIGger[:SEQuence]:EXTernal[1]|2:LEVel <voltage> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

List of Commands

:TRIGger[:SEQuence]:EXTernal[1]|2:LEVel?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

:TRIGger[:SEQuence]:EXTernal[1]|2:SLOPe NEGative|POSitive . . . . . . . . . . . . . . . . . . . . . . . . 137

:TRIGger[:SEQuence]:EXTernal[1]|2:SLOPe? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

:TRIGger[:SEQuence]:FRAMe:PERiod <time> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

:TRIGger[:SEQuence]:FRAMe:PERiod? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

:TRIGger[:SEQuence]:FRAMe:SYNCmode OFF|EXTFront|EXTRear . . . . . . . . . . . . . . . . . . . . . 140

:TRIGger[:SEQuence]:FRAMe:SYNCmode:OFFSet <time> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

:TRIGger[:SEQuence]:FRAMe:SYNCmode:OFFSet? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

:TRIGger[:SEQuence]:FRAMe:SYNCmode? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140

:TRIGger[:SEQuence]:HOLDoff <time> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

:TRIGger[:SEQuence]:HOLDoff? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

:TRIGger[:SEQuence]:IF:DELay <time>. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

:TRIGger[:SEQuence]:IF:DELay? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

:TRIGger[:SEQuence]:IF:LEVel <ampl> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

:TRIGger[:SEQuence]:IF:LEVel? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

:TRIGger[:SEQuence]:IF:SLOPe NEGative|POSitive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136

:TRIGger[:SEQuence]:IF:SLOPe? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136

:TRIGger[:SEQuence]:RFBurst:DELay <time> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134

:TRIGger[:SEQuence]:RFBurst:DELay? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134

:TRIGger[:SEQuence]:RFBurst:LEVel <rel_power>. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134

:TRIGger[:SEQuence]:RFBurst:LEVel?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134

List of Commands

:TRIGger[:SEQuence]:RFBurst:SLOPe NEGative|POSitive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .135

:TRIGger[:SEQuence]:RFBurst:SLOPe?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .135

[:SENSe]:CORRection:BTS:[:RF]:LOSS <real> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .128

[:SENSe]:CORRection:BTS:[:RF]:LOSS? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .128

[:SENSe]:CORRection:MS:[:RF]:LOSS <real> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .128

[:SENSe]:CORRection:MS:[:RF]:LOSS? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .128

[:SENSe]:EVM:ADC:RANGe AUTO|NONE|Autopeaklock|ENVL|0dB|6dB|12dB|18dB. . . . .170

[:SENSe]:EVM:ADC:RANGe? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .170

[:SENSe]:EVM:ADRoop:COMPensation ON|OFF|0|1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .174

[:SENSe]:EVM:ADRoop:COMPensation? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .174

List of Commands

[:SENSe]:EVM:AVERage:COUNt <integer> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .151

[:SENSe]:EVM:AVERage:COUNt? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .151

[:SENSe]:EVM:AVERage:TCONtrol EXPonential|REPeat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .152

[:SENSe]:EVM:AVERage:TCONtrol? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .152

[:SENSe]:EVM:AVERage:TRACe[:TYPE] RMS|MAXimum|MINimum . . . . . . . . . . . . . . . . . . . . .153

[:SENSe]:EVM:AVERage:TRACe[:TYPE]? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .153

[:SENSe]:EVM:AVERage[:STATe] OFF|ON|0|1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .151

[:SENSe]:EVM:AVERage[:STATe]? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .151

[:SENSe]:EVM:CADJust <real> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .168

[:SENSe]:EVM:CADJust? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .168

[:SENSe]:EVM:CLOCk NORMal|WIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .165

[:SENSe]:EVM:CLOCk:WIDE:AUTO ON|OFF|0|1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .173

[:SENSe]:EVM:CLOCk:WIDE:AUTO? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .173

[:SENSe]:EVM:CLOCk:WIDE:MRANge <freq>. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .174

[:SENSe]:EVM:CLOCk:WIDE:MRANge? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .174

[:SENSe]:EVM:CLOCk?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .165

[:SENSe]:EVM:CMODe RMS| MAXimum. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .169

[:SENSe]:EVM:CMODe? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .169

[:SENSe]:EVM:EQUalization:CONVergence <real> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .164

[:SENSe]:EVM:EQUalization:CONVergence? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .164

[:SENSe]:EVM:EQUalization:FLENgth <integer> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .163

List of Commands

[:SENSe]:EVM:EQUalization:FLENgth? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163

[:SENSe]:EVM:EQUalization:HOLD[:STATe] OFF|ON|0|1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164

[:SENSe]:EVM:EQUalization:HOLD[:STATe]?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164

[:SENSe]:EVM:EQUalization:RESet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165

[:SENSe]:EVM:EQUalization[:STATe] OFF|ON|0|1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163

[:SENSe]:EVM:EQUalization[:STATe]?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163

[:SENSe]:EVM:FFT:WINDow[:TYPE] UNIForm|FTOP|HANNing|GAUSsian . . . . . . . . . . . . . . 165

[:SENSe]:EVM:FFT:WINDow[:TYPE]? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165

[:SENSe]:EVM:IFBWidth <frequency> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

[:SENSe]:EVM:IFBWidth:AUTO OFF|ON|0|1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

List of Commands

[:SENSe]:EVM:IFBWidth:AUTO? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

[:SENSe]:EVM:IFBWidth? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

[:SENSe]:EVM:IFPath NARROW|WIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171

[:SENSe]:EVM:IFPath? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171

[:SENSe]:EVM:IUPDate ON|OFF|0|1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175

[:SENSe]:EVM:IUPDate? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175

[:SENSe]:EVM:NORMalize:FSK ON|OFF|0|1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170

[:SENSe]:EVM:NORMalize:FSK? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170

[:SENSe]:EVM:NORMalize:IQ MMDPoint|MRMS|MRDPoint . . . . . . . . . . . . . . . . . . . . . . . . . . . 170

[:SENSe]:EVM:NORMalize:IQ? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170

[:SENSe]:EVM:SPECtrum NORMal|INVert . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168

[:SENSe]:EVM:SPECtrum? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168

[:SENSe]:EVM:SWEep:POINts <integer> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158

[:SENSe]:EVM:SWEep:POINts? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158

[:SENSe]:EVM:SYNC:SLENgth <seconds> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161

[:SENSe]:EVM:SYNC:SLENgth? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161

[:SENSe]:EVM:SYNC:SOURce NONE|RFAMplitude|SWORd|SWBurst . . . . . . . . . . . . . . . . . . 159

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

[:SENSe]:EVM:SYNC:STHReshold <rel_ampl> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160

[:SENSe]:EVM:SYNC:STHReshold? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160

[:SENSe]:EVM:SYNC:SWORd:LENGth <integer> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161

List of Commands

[:SENSe]:EVM:SYNC:SWORd:LENGth? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .161

[:SENSe]:EVM:SYNC:SWORd:OFFSet <integer> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .162

[:SENSe]:EVM:SYNC:SWORd:OFFSet?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .162

[:SENSe]:EVM:SYNC:SWORd:PATTern <hexadecimal> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .161

[:SENSe]:EVM:SYNC:SWORd:PATTern?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .161

[:SENSe]:EVM:TRIGger:SOURce IMMediate|IF|RFBurst

|EXTernal[1]|EXTernal2|FRAMe. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .159

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

[:SENSe]:EVM:WBIF:ADC:DITHer OFF|ON|0|1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .172

[:SENSe]:EVM:WBIF:ADC:DITHer? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .172

List of Commands

[:SENSe]:EVM:WBIF:ADCCorrect OFF|ON|0|1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .172

[:SENSe]:EVM:WBIF:ADCCorrect? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .172

[:SENSe]:EVM:WBIF:FLATness OFF|ON|0|1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .172

[:SENSe]:EVM:WBIF:FLATness? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .172

[:SENSe]:EVM:WBIF:IFGain <integer>. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .171

[:SENSe]:EVM:WBIF:IFGain? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .171

[:SENSe]:EVM:WBIF:TRIGger:EOFFset? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .180

[:SENSe]:EVM:WBIF:TRIGger:INTerpolate OFF|ON|0|1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .173

[:SENSe]:EVM:WBIF:TRIGger:INTerpolate?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .173

[:SENSe]:FEED RF|AREFerence|EMIXer|IFALign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .126

[:SENSe]:FEED? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .126

[:SENSe]:FREQuency:CENTer <freq> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .125

[:SENSe]:FREQuency:CENTer:STEP:AUTO OFF|ON|0|1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .125

[:SENSe]:FREQuency:CENTer:STEP:AUTO? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .125

[:SENSe]:FREQuency:CENTer:STEP[:INCRement] <freq> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .125

[:SENSe]:FREQuency:CENTer:STEP[:INCRement]? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .125

[:SENSe]:FREQuency:CENTer? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .125

[:SENSe]:POWer:GAIN:STATe] OFF|ON|0|1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .128

[:SENSe]:POWer:GAIN:STATe]? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .128

[:SENSe]:POWer[:RF]:ATTenuation <rel_power> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .127

[:SENSe]:POWer[:RF]:ATTenuation? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .127

List of Commands

[:SENSe]:POWer[:RF]:MW:PRESelector[:STATe] OFF|ON|0|1 . . . . . . . . . . . . . . . . . . . . . . . . . . 127

[:SENSe]:POWer[:RF]:MW:PRESelector[:STATe]? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

[:SENSe]:RADio:DEVice BTS|MS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

[:SENSe]:RADio:DEVice? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

[:SENSe]:RADio:STANdard:ALPHa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

[:SENSe]:RADio:STANdard:ALPHa? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

[:SENSe]:RADio:STANdard:FILTer:MEASurement NONE|RNYQuist

[:SENSe]:RADio:STANdard:FILTer:MEASurement? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

[:SENSe]:RADio:STANdard:FILTer:REFerence RNYQuist|NYQuist|GAUSsian|CD-

MA|EDGE|RECTangle|HSINe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

List of Commands

[:SENSe]:RADio:STANdard:FILTer:REFerence? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

[:SENSe]:RADio:STANdard:MODulation? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

[:SENSe]:RADio:STANdard:MODulation QPSK|BPSK|OQPSK|PI4DQPSK|D8PSK|DQPSK|EPSK|QAM16|QAM32 |QAM64|QAM128|QAM256|FSK2|FSK4|FSK8|MSK1|MSK2|EDGE|

DVBQAM16|DVBQAM32|DVBQAM64|DVBQAM128|DVBQAM256. . . . . . . . . . . . . . . . . . . . . 155

[:SENSe]:RADio:STANdard:SRATe <frequency> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

[:SENSe]:RADio:STANdard:SRATe? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

[:SENSe]:RADio:STANdard[:SELect] CDMA|CDMA2K|WCDMA|NADC|

[:SENSe]:RADio:STANdard[:SELect]? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

List of Commands

1 Introduction

This chapter provides overall information on the Agilent PSA Series Flexible Digital Modulation Analysis Option 241 and describes the measurements made by the analyzer. If you have purchased this option separately, there are installation instructions provided in this section for adding this option to your analyzer.

Introduction

What Does the Agilent PSA Option 241 Do?

This instrument can help determine if a digitally modulated source or transmitter is working correctly. The instrument will demodulate a broad range of digital signals, like FSK, PSK, and QAM. Option 241 also demodulates signals created in many standard communications formats, like EDGE, cdma2000, and W-CDMA. You may alter the demodulation parameters for specialized analysis.

This instrument will demodulate signals that use the following formats:

•MSK

•QPSK

•8PSK

•BPSK

• π/4 DQPSK

•DQPSK

•D8PSK

• Offset QPSK

• QAM16, 32, 64, 128, 256

• DVB QAM 16, 32, 64, 128, 256

• FSK 2, 4, 8 states

This instrument will also demodulate signals that conform to the following standard communications formats:

Introduction

• GSM BTS and MS

• EDGE BTS and MS

• W-CDMA BTS and MS

• cdma2000 SR1 BTS and MS

• cdmaOne BTS and MS

• NADC BTS and MS

• PDC BTS and MS

• PHS BTS and MS

• TETRA BTS and MS

• Bluetooth

• ZigBee 2450 MHz

16 Chapter 1

Introduction

What Does the Agilent PSA Option 241 Do?

•VDL Mode 3

• APCO25 phase1

NOTE PSA option 241 can analyze digital modulation for a single code channel

only. If multiple code channels are transmitted, synchronization will fail, and incorrect EVM results will be obtained. For modulation quality measurements of multiple code channels, Modulation Accuracy and Code Domain measurements must be performed by a full-featured standard-based personality, like PSA Option BAF for W-CDMA.

For infrastructure testing and analysis, base station or mobile equipment can be tested on a non-interference basis using the appropriate power splitters, couplers, and attenuators. For details see

Chapter 2 , “Making Measurements,” on page 25.

Introduction

Chapter 1 17

Introduction

Installing Optional Measurement Personalities

When you install a measurement personality, you need to follow a three step process:

1. Determine whether your memory capacity is sufficient to contain all the options you want to load. If not, decide which options you want to install now, and consider upgrading your memory. Details follow in

“Do You Have Enough Memory to Load All Your Personality Options?” on page 18.

2. Install the measurement personality firmware into the instrument memory. Details follow in “Loading an Optional Measurement

Personality” on page 22.

3. Enter a license key that activates the measurement personality. Details follow in “Obtaining and Installing a License Key” on page

22.

Adding measurement personalities requires the purchase of an upgrade kit for the desired option. The upgrade kit contains the measurement personality firmware and an entitlement certificate that is used to generate a license key from the internet website. A separate license key is required for each option on a specific instrument serial number and host ID.

For the latest information on Agilent Spectrum Analyzer options and upgrade kits, visit the following web location:

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

Introduction

Do You Have Enough Memory to Load All Your Personality Options?

If you do not have memory limitations then you can skip ahead to the next section “Loading an Optional Measurement Personality” on

page 22. If after installing your options you get error messages relating

to memory issues, you can return to this section to learn more about how to optimize your configuration.

If you have 64 MBytes of memory installed in your instrument, you should have enough memory to install at least four optional personalities, with plenty of memory for data and states.

The optional measurement personalities require different amounts of memory. So the number of personalities that you can load varies. This is also impacted by how much data you need to save. If you are having memory errors you must swap the applications in or out of memory as needed. If you only have 48 MBytes of memory, you can upgrade your

18 Chapter 1

Introduction

Installing Optional Measurement Personalities

hardware to 64 MBytes.

Additional memory can be added to any PSA Series analyzer by installing Option 115. With this option installed, you can install all currently available measurement personalities in your analyzer and still have memory space to store more state and trace files than would otherwise be possible.

To see the size of your installed memory for PSA Series Spectrum Analyzers:

1. Ensure that the spectrum analyzer is in spectrum analyzer mode because this can affect the screen size.

2. Press

3. Press

System, Show System. Under Options look for 115.

System, More, Show Hdwr.

4. Read Flash Memory size in the table.

PSA Flash Memory Size

64 Mbytes 32.5 MBytes 30.0 MBytes

48 Mbytes 16.9 MBytes 14.3 MBytes

PSA Compact Flash Memory Size

512 Mbytes (Opt. 115) 512 MBytes

Available Memory Without Option B7J and Option 122 or 140

Available Additional Memory for Measurement Personalities

Available Memory With Option B7J and Option 122 or 140

If you have 48 MBytes of memory, and you want to install more than 3 optional personalities, you may need to manage your memory resources. The following section, “How to Predict Your Memory

Requirements” on page 20, will help you decide how to configure your

installed options to provide optimal operation.

Introduction

Chapter 1 19

Introduction

Installing Optional Measurement Personalities

How to Predict Your Memory Requirements

If you plan to install many optional personalities, you should review your memory requirements, so you can determine whether you have enough memory (unless you have a PSA Series with Option 115). There is an Agilent “Memory Calculator” available online that can help you do this, or you can make a calculated approximation using the information that follows. You will need to know your instrument’s installed memory size as determined in the previous section and then select your desired applications.

NOTE If you have a PSA Series analyzer with Option 115, there is adequate

memory to install all of the available optional personalities in your instrument.

To calculate the available memory on your PSA, see:

http://sa.tm.agilent.com/PSA/memory/

Select the “Memory Calculator” link. You can try any combination of available personalities to see if your desired configuration is compatible with your installed memory.

NOTE After loading all your optional measurement personalities, you should

have a reserve of ~2 MBytes memory to facilitate mode switching. Less available memory will increase mode switching time. For example, if you employ excessive free memory by saving files of states and/or data, your mode switching time can increase to more than a minute.

You can manually estimate your total memory requirements by adding up the memory allocations described in the following steps. Compare the desired total with the available memory that you identified in the previous section.

Introduction

1. Program memory - Select option requirements from the table

“Measurement Personality Options and Memory Required” on page 21.

2. Shared libraries require 7.72 MBytes.

3. The recommended mode swap space is 2 MBytes.

4. Screens - .gif files need 20-25 kBytes each.

5. State memory - State file sizes range from 21 kB for SA mode to 40 kB for W-CDMA. The state of every mode accessed since power-on will be saved in the state file. File sizes can exceed 150 kB each when several modes are accessed, for each state file saved.

TIP State memory retains settings for all states accessed before the Save

State

command. To reduce this usage to a minimum, reduce the modes

accessed before the

Save State is executed. You can set the PSA to boot

into a selected mode by accessing the desired mode, then pressing the

System, Power On/Preset, Power On keys and toggle the setting to Last.

20 Chapter 1

Installing Optional Measurement Personalities

Measurement Personality Options and Memory Required

Introduction

Personality Options for PSA Series Spectrum Analyzers

Option File Size

(PSA Rev: A.10)

cdmaOne measurement personality BAC 1.91 Mbytes

NADC and PDC measurement personalities (not

BAE 2.43 Mbytes

available separately)

W-CDMA or W-CDMA, HSDPA, HSUPA

BAF, 210

5.38 Mbytes

measurement personality

cdma2000 or cdma2000 w/ 1xEV-DV measurement

B78, 214

4.00 Mbytes

personality

1xEV-DO measurement personality 204

GSM (with EDGE) measurement personality 202

Shared measurement library

n/a 7.72 Mbytes

Phase Noise measurement personality 226

Noise Figure measurement personality 219

Basic measurement personality with digital demod

B7J Cannot be deleted

hardware

Programming Code Compatibility Suited (8560

266

5.61 Mbytes

3.56 Mbytes

2.82 Mbytes

4.68 Mbytes

(2.64 Mbytes)

1.18 Mbytes

Series, 8590 Series, and 8566/8568)

TD-SCDMA Power measurement personality 211

TD-SCDMA Modulation Analysis or TD-SCDMA

212, 213 1.82 Mbytes

5.47 Mbytes

Modulation Analysis w/ HSDPA/8PSK measurement personality

Flexible Digital Modulation Analysis 241

WLAN measurement personality 217

External Source Control 215

Measuring Receiver Personality

233

2.11 Mbytes

3.24 Mbytes

0.72 Mbytes

2.91 Mbytes

(available with Option 23A - Trigger support for AM/FM/PM and Option 23B - CCITT filter)

EMC Analyzer 239

4.06 Mbytes

a. Available as of the print date of this guide. b. Many PSA Series personality options use a 7.72 Mbyte shared measurement library. If

you are loading multiple personalities that use this library, you only need to add this

memory allocation once. c. Shared measurement library allocation not required. d. This is a no charge option that does not require a license key.

Introduction

Chapter 1 21

Introduction

Installing Optional Measurement Personalities

Memory Upgrade Kits

The PSA 64 MByte Memory Upgrade kit part number is E4440AU-ANE. The PSA Compact Flash Upgrade kit part number is E4440AU-115.

For more information about memory upgrade kits contact your local sales office, service office, or see:

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

Loading an Optional Measurement Personality

You must use a PC to load the desired personality option into the instrument memory. Loading can be done from a firmware CD-ROM or by downloading the update program from the internet. An automatic loading program comes with the files and runs from your PC.

You can check the Agilent internet website for the latest PSA firmware versions available for downloading:

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

NOTE When you add a new option, or update an existing option, you will get

the updated versions of all your current options as they are all reloaded simultaneously. This process may also require you to update the instrument core firmware so that it is compatible with the new option.

Depending on your installed hardware memory, you may not be able to fit all of the available measurement personalities in instrument memory at the same time. You may need to delete an existing option file from memory and load the one you want. Use the automatic update program that is provided with the files. Refer to the table showing

“Measurement Personality Options and Memory Required” on page 21.

The approximate memory requirements for the options are listed in this

Introduction

table. These numbers are worst case examples. Some options share components and libraries, therefore the total memory usage of multiple options may not be exactly equal to the combined total.

Obtaining and Installing a License Key

If you purchase an optional personality that requires installation, you will receive an “Entitlement Certificate” which may be redeemed for a license key specific to one instrument. Follow the instructions that accompany the certificate to obtain your license key.

To install a license key for the selected personality option, use the following procedure:

NOTE You can also use this procedure to reinstall a license key that has been

deleted during an uninstall process, or lost due to a memory failure.

22 Chapter 1

Introduction

Installing Optional Measurement Personalities

1. Press System, More, More, Licensing, Option to accesses the alpha editor. Use this alpha editor to enter letters (upper-case), and the front-panel numeric keys to enter numbers for the option designation. You will validate your option entry in the active function area of the display. Then, press the

Enter key.

2. Press

License Key to enter the letters and digits of your license key.

You will validate your license key entry in the active function area of the display. Then, press the

3. Press the

Activate License key.

Enter key.

Viewing a License Key

Measurement personalities purchased with your instrument have been installed and activated at the factory before shipment. The instrument requires a License Key unique to every measurement personality purchased. The license key is a hexadecimal number specific to your measurement personality, instrument serial number and host ID. It enables you to install, or reactivate that particular personality.

Use the following procedure to display the license key unique to your personality option that is already installed in your PSA:

Press

Personality key displays the personalities loaded, version

information, and whether the personality is licensed.

NOTE You will want to keep a copy of your license key in a secure location.

Press of the display that shows the license numbers. If you should lose your license key, call your nearest Agilent Technologies service or sales office for assistance.

System, More, More, Licensing, Show License. The System,

System, More, then Licensing, Show License, and print out a copy

Introduction

Using the Delete License Key on PSA

This key will make the option unavailable for use, but will not delete it from memory. Write down the 12-digit license key for the option before you delete it. If you want to use that measurement personality later, you will need the license key to reactivate the personality firmware.

NOTE Using the Delete License key does not remove the personality from the

instrument memory, and does not free memory to be available to install another option. If you need to free memory to install another option, refer to the instructions for loading firmware updates located at the URL : http://www.agilent.com/find/psa/

1. Press will activate the alpha editor menu. Use the alpha editor to enter the

Chapter 1 23

System, More, More, Licensing, Option. Pressing the Option key

Introduction

Installing Optional Measurement Personalities

letters (upper-case) and the front-panel numeric keyboard to enter the digits (if required) for the option, then press the

Enter key. As you

enter the option, you will see your entry in the active function area of the display.

2. Press

Delete License to remove the license key from memory.

Ordering Optional Measurement Personalities

When you order a personality option, you will receive an entitlement certificate. You will need to go to the Web site to redeem your entitlement certificate for a license key. You will need to provide your instrument serial number and host ID, and the entitlement certificate number.

Required Information: Front Panel Key Path:

Model #: (Ex. E4440A)

Host ID: __________________

Instrument Serial Number: __________________

System, Show System

Introduction

24 Chapter 1

2 Making Measurements

This chapter describes procedures used to set up and analyze digitally modulated signals. Details of the steps necessary for accurate modulation analysis of digital signals are provided, and examples of the measurement capability of PSA Option 241 for analysis of various modulation formats are shown.

Making Measurements

Introduction

This chapter provides measurement and troubleshooting procedures and also shows example results obtained using the PSA Option 241 Flexible Digital Modulation Analysis measurement personality. When correctly set up, this PSA personality demodulates basic formats, cellular formats, and wireless connectivity formats and performs a suite of vector-analysis measurements to analyze digital modulation quality.

There are three measurements available in this mode: Modulation Analysis, Spectrum, and Waveform. This chapter concentrates on the Modulation Analysis measurement. For more details about Spectrum and Waveform measurements, please refer to the PSA Basic Mode Guide.

NOTE PSA option 241 can analyze digital modulation for a single code channel

The following PSA hardware options are compatible with this measurement personality, as well as for Basic Mode Spectrum and Wavefor m measur e ments:

• Option 122, 80 MHz Bandwidth Digitizer

• Option 140, 40 MHz Bandwidth Digitizer

• Option 123, Preselector Bypass (required for Options 122 or 140)

For more information on using Options 122, 123, and 140 see the PSA Basic Mode Guide.

The following subjects are presented in this chapter:

• “Setting Up the Test Equipment and DUT” on page 28

This section describes how to setup your test equipment and DUT to make modulation measurements on the PSA. It also describes instrument preset types.

• “Determining the RF Parameters of Your Signal” on page 31

This section describes how to use the spectrum and waveform measurements to view the RF parameters of your signal.

• “Modulation Analysis Measurements in 8 Steps” on page 48

Making Measurements

This section describes steps to set up the PSA to demodulate industry standard radio formats or to use the flexible modulation

26 Chapter 2

Making Measurements

Introduction

settings to demodulate customized digital signals.

• “Modulation Analysis Measurement Final Checks” on page 50

This section describes what you should expect from a modulation analysis measurement and tips to improve your measurement.

• “Modifying Measurement Setup Parameters” on page 52

This section describes how to setup demodulation parameters, triggering, burst synchronization and equalization.

• “Measuring Digital Modulation Formats” on page 62

This section describes the different modulation analysis views using industry standard communication formats.

• “Analyzing and Troubleshooting Digital Signals” on page 95

This section describes a troubleshooting procedure to determine the causes of impairments that degrade signal quality.

• “Interpreting Error Codes” on page 119

This section details common error messages and offers hints to assist you in resolving them.

Making Measurements

Chapter 2 27

Making Measurements

Setting Up the Test Equipment and DUT

Making the Initial Signal Connection

CAUTION Before connecting a signal to the instrument, make sure the instrument

can safely accept the signal level provided. The signal level limits are marked next to the connectors on the front panel.

See “Input/Output” on page 126 for details on selecting input ports, setting internal attenuation to prevent overloading the input port, and details of

Configuring a MS Measurement System

The mobile station (MS) under test has to be set to transmit the RF power remotely through the system controller. This transmitting signal is connected to the instruments RF input port. Connect the equipment as shown.

Int Preamp operation.

Figure 2-1 Mobile Station Measurement System

Step 1. Using the appropriate cables, adapters, and circulator, connect the

output signal of the MS to the RF input of the instrument.

Step 2. Connect the base transmission station simulator or signal generator to

the MS through a circulator to initiate a link constructed with sync and pilot channels, if required.

Making Measurements

Step 3. Connect a BNC cable between the 10 MHz OUT port of the signal

generator and the EXT REF IN port of the instrument.

Step 4. Connect the system controller to the MS through the serial bus cable to

control the MS operation.

28 Chapter 2

Configuring a BTS Measurement System

The base transmission station (BTS) under test has to be set to transmit the RF power remotely through the system controller. The transmitting signal from the BTS is summed with the interferer and connected to the instruments RF input port. Connect the equipment as shown.

Figure 2-2 Base Station Measurement System

Making Measurements

Setting Up the Test Equipment and DUT

Step 1. Using appropriate amplifier, circulators, etc., connect the RF uplink

signal from a signal generator or MS to the BTS RF Input connector.

Step 2. Connect the RF Output signal from the BTS to the RF Input port of the

instrument through an attenuator.

Step 3. Connect a BNC cable between the 10 MHz OUT port of the signal

generator and the EXT REF IN port of the instrument.

Step 4. Connect the system controller to the BTS with the serial bus cable.

NOTE When making BTS or MS measurements, you may need to provide a

synchronization trigger to the PSA. Selections are detailed in the section “Setting up a Trigger Source” on page 54 (connections not shown).

Making Measurements

Chapter 2 29

Making Measurements

Setting Up the Test Equipment and DUT

Using Instrument Presets

If you want to set your current measurement personality to a known, factory default state use instrument preset. You have the option of setting the instrument preset to factory, mode or user defined preset types. To restore the PSA default settings in the mode, use retain the current mode.

Step 1. Select the preset type:

Mode preset to initialize the modulation parameters and

Modulation Analysis

Press Press

System, Power On/Preset, Preset Type. User or Mode or Factory.

Factory Preset - Returns the analyzer to current mode is not spectrum analysis) and initializes the instrument settings to factory settings in

Spectrum Analysis mode.

Mode Preset - The analyzer is preset within its current mode. Instrument settings are reset to a factory default state for the current mode.

User Preset - The instrument is preset to a saved configuration.

Step 2. Save a user defined preset state:

Press

System, Power On/Preset, Save User Preset.

The PSA can save one user defined preset state. When user preset is selected and

Preset is pressed, the analyzer will prompt you to select

user, mode or factory preset. When in mode and factory preset the analyzer will not prompt you to choose the preset type.

Spectrum Analysis mode (if the

Making Measurements

30 Chapter 2

Making Measurements

Determining the RF Parameters of Your Signal

This procedure uses the spectrum and waveform measurements in the PSA Option 241 modulation analysis measurement personality to help determine the RF parameters of your signal. The spectrum measurement is used to view the signal in the frequency domain, verifying the center frequency of the carrier and the frequency span of the signal. The waveform measurement is used to view the signal in the time domain and is very useful for determining trigger conditions.

NOTE The spectrum and waveform measurements available in

PSA Option 241 are the same as those available in basic mode. Spectrum and waveform measurements are provided in the modulation analysis mode for your convenience to avoid having to switch to basic mode for their use. Please refer to the PSA Basic Mode User’s Guide Option B7J for more detail on the spectrum and waveform measurements, remote commands, front-panel keys, conceptual information and menu maps.

Using the Spectrum Measurement to View the RF Parameters of the Signal Under Test

The spectrum measurement is the default measurement for PSA Option 241. Use the spectrum view to make sure your demodulation measurement is focused on your signal of interest.

Step 1. Activate the spectrum measurement view:

Press Press

Step 2. Set the center frequency to your signal’s carrier frequency:

Press the center frequency, then press a units key, like entry.

Step 3. Set the frequency span to view your entire signal:

Press frequency span, then press a units key, like

When Option 123, Preselector Bypass is installed, along with either PSA Option 122, 80 MHz Bandwidth Digitizer hardware, or PSA Option 140, 40 MHz Bandwidth Digitizer hardware, together they may be used to increase the capture bandwidth of signals. Press

More, IF Path, and toggle the setting to Wide to increase the available IF

bandwidth of the instrument. See “Wideband Setup” on page 171 for more details of using the wideband IF path.

MODE, Digital Modulation. MEASURE, Spectrum (Freq Domain).

FREQUENCY Channel, then use the front-panel keypad to input

GHz, to complete the

SPAN X Scale, then use the front-panel keypad to input the

MHz, to complete the entry.

Making Measurements

Meas Setup,

Chapter 2 31

Making Measurements

Determining the RF Parameters of Your Signal

CAUTION Make sure your signal is not overloading the instrument. If the Input

Overload annunciator is active at the lower left edge of the spectrum display, adjust the RF input power, or the internal attenuation as needed.

Check: The signal’s spectrum should appear as a distinct, elevated region of noise 20 dB or more above the analyzer noise floor. If your signal is not significantly above the measurement noise floor, you may need to modify your measurement configuration by adding amplification. Broad, glitching sidebands indicate bursts or other transients, which can be handled with triggering or the Sync Search function (see “Setting Burst/Sync Properties” on page 55).

Spectrum (Frequency Domain) Measurements

This section explains how to make a frequency domain measurement on a cellular base station. An adjacent or an interfering signal can also be applied, if desired, during spectrum measurements.

If installed, you may use PSA Option 122, the 80 MHz Bandwidth Digitizer hardware, or PSA Option 140, the 40 MHz Bandwidth Digitizer hardware to perform Spectrum measurements of wideband signals using Basic Mode.

Configuring the Measurement System

This example shows a base station (BTS) under test, set up to transmit RF power, and being controlled remotely by a system controller. The transmitting signal is connected to the analyzer RF input port. Connect the equipment as shown.

Making Measurements

32 Chapter 2

Figure 2-3 Spectrum Measurement System

1. Using the appropriate cables, adapters, and circulator, connect the output signal of the BTS to the RF input of the instrument.

Making Measurements

Determining the RF Parameters of Your Signal

2. Connect the base transmission station simulator or signal generator to the BTS through a circulator to initiate a link constructed with sync and pilot channels, if required.

3. Connect a BNC cable between the 10 MHz OUT port of the signal generator and the EXT REF IN port of the instrument.

4. Connect the system controller to the BTS through the serial bus cable to control the BTS operation.

Setting the BTS

From the base transmission station simulator and the system controller, set up a call using loopback mode to allow the BTS to transmit an RF signal.

Measurement Procedure

Step 1. Press

Step 2. Press

measurements.

Preset to preset the instrument.

Making Measurements

MODE, Digital Modulation to enable the Digital Modulation Mode

Step 3. To set the measurement center frequency, press

and enter a numerical frequency using the front-panel keypad. Complete the entry by selecting a units key, like

Step 4. Press

Chapter 2 33

SPAN and enter a numerical span using the front-panel keypad.

FREQUENCY Channel

MHz.

Making Measurements

Determining the RF Parameters of Your Signal

Press MHz to set the measurement span in MHz.

Step 5. Press

MEASURE to initiate the Spectrum measurement, which is the

default measurement for the selected Mode.

NOTE A display with both a Spectrum window and an I/Q Waveform window

will appear when you activate a Spectrum measurement. The active window is outlined in green. Changes to

Amplitude settings will affect only the active window. Use the Next Window

key to select a different window, and the Zoom key to enlarge a

FREQUENCY, Span, or

window.

The default display shows both

Current (yellow trace) and Average (blue

trace) data. To make viewing the display easier, you can view either the

Current trace or Average separately.

•Press

Trace/View, Trace Display, and select the trace(s) desired for

display.

Making Measurements

34 Chapter 2

Making Measurements

Determining the RF Parameters of Your Signal

Figure 2-4 Spectrum Measurement - Spectrum and I/Q Waveform (Default

View)

Step 6. Press

measurement result display, including the following:

Spectrum - Provides a combination view of the Spectrum graph in

• parameters of power versus frequency with semi-log graticules, and the I/Q waveform graph in parameters of voltage and time. Changes to the frequency span or power will sometimes affect data acquisition. This is equivalent to changing the selected window with the

Spectrum (Time Domain) I/Q Waveform - This graph is shown below the

Spectrum graph in the default dual-window display. I/Q Waveform

provides a view of the I/Q waveform in parameters of voltage versus time in linear scale. Changes to sweep time or resolution bandwidth can affect data acquisition.

View/Trace to display a menu allowing selection of another

Next Window key.

Making Measurements

Chapter 2 35

Making Measurements

Determining the RF Parameters of Your Signal

Figure 2-5 Spectrum (Time Domain) Measurement - I/Q Waveform Result

Step 7. To make a measurement repeatedly, press

toggle the setting from

Single to Cont.

Meas Control, Measure to

Step 8. For PSA, if Option 122 or 140 is installed, you may use the wideband IF

hardware to view a wide bandwidth signal in the Spectrum view. The I/Q Waveform view will be correctly demodulated to the I and Q components over the entire display bandwidth.

•Press

MODE, and select Modulation Analysis to be able to use the

Wideband IF path.

•Press

MEASURE, and select the Spectrum measurement.

MEAS SETUP and toggle the IF Path key to select Wide. Adjust

the span to view up to 80 MHz for Option 122, or up to 40 MHz for Option 140 around your selected center frequency.

The example shown below is a 54 carrier OFDM signal which has a

− 10 dB bandwidth greater than 16 MHz, with skirts to over twice that bandwidth. Delta markers are shown measuring the peak bandwidth.

Making Measurements

36 Chapter 2

Making Measurements

Determining the RF Parameters of Your Signal

Figure 2-6 Spectrum Measurement - Spectrum Zoom View with Opt. 122−

80 MHz Bandwidth Digitizer Hardware

Chapter 2 37

Making Measurements

Determining the RF Parameters of Your Signal

The example shown below is a 802.11 WLAN signal which has an instantaneous bandwidth of over 36 MHz. Only the Average trace is displayed.

When using the widest spans, the Resolution Bandwidth may be limited by the maximum number of points available for a Spectrum measurement. If your desired setting exceeds the available number of points, the maximum number available will be used, and an error message will be displayed.

Figure 2-7 Spectrum Measurement - Spectrum Zoom View with Opt. 122−

80 MHz Bandwidth Digitizer Hardware

Making Measurements

38 Chapter 2

Making Measurements

Determining the RF Parameters of Your Signal

The example shown below is a Spectrum View of the center 20 MHz of a Noise Power Ratio measurement. If you extend the Span to the full 80 MHz bandwidth, individual carriers displayed may merge, as they can be limited by screen resolution and resolution bandwidth. Only the Average data trace is displayed in the example below.

Figure 2-8 Spectrum Measurement - Spectrum View with Opt. 122− 80 MHz

Bandwidth Digitizer Hardware

Chapter 2 39

Making Measurements

Determining the RF Parameters of Your Signal

The wideband signal example shown below is 16 W-CDMA carriers, each occupying 5 MHz of bandwidth. The full 80 MHz of available demodulation bandwidth for the Spectrum measurement is used. Only the Average trace is displayed. Note the demodulated composite I/Q waveform for the entire 80 MHz BW signal in the

I/Q Waveform window

below. A peak search marker has been applied to the composite waveform.

Figure 2-9 Spectrum Measurement - Spectrum Zoom View with Opt. 122−

80 MHz Bandwidth Digitizer Hardware

Making Measurements

Step 9. Press

measurement parameters from the default condition.

For more details about using PSA Wide Bandwidth BW Digitizing Hardware Options 122 and 140, including detailed functional descriptions and SCPI commands and concepts, see the PSA Basic Mode Guide.

40 Chapter 2

Meas Setup, More to check the keys available to change the

Determining the RF Parameters of Your Signal

Using the Waveform Measurement to Set Up Triggering (for burst signals)

You can use the waveform measurement to view your signal in the time domain and to help select the appropriate trigger to acquire your signal.

Step 1. Activate the waveform measurement view:

Making Measurements

Press

MEASURE, Waveform (Time Domain).

Step 2. Adjust the scale of the x-axis to view the complete signal waveform:

Press the scale/div, then press a units key, like

SPAN X Scale, Scale/Div, then use the front-panel keypad to input

µs, to complete the entry.

Step 3. Select a trigger source (free run is the default setting):

Press

Meas Setup, Trig Source, then select one of the available trigger

sources.

Triggering is unnecessary for most signals. For TDMA and other burst signals, PSA Option 241 will readily acquire a “framed” signal.

NOTE In the waveform measurement the Burst/Sync Search menu is not

available. measure mode.

Burst/Sync Search is available in the Modulation Analysis

Frame Timer (located under the Trig S e t up menu) must be

used to trigger on framed signals in the Waveform measurement.

Step 4. Set up the trigger conditions:

Press

Trig or Mode Setup, Trigg e r Setup , then choose a trigger mode.

In the trigger mode set the delay, peak level and positive or negative edge slope trigger. You can also set up trigger holdoff, auto trigger timing and frame timer settings.

Chapter 2 41

Making Measurements

Determining the RF Parameters of Your Signal

NOTE You can modify the trigger setup settings in an editable table view

under the

Mode Setup, Trigger Setup... key. You may select any

parameter to change the settings by pressing the Left/Right Arrow keys. The current selection is highlighted in yellow or blue. You may use the Up/Down Arrow keys, front-panel knob or the front-panel keypad to input changes to the selected field.

Waveform (Time Domain) Measurements

This section explains how to make Waveform (Time Domain) measurements on a cellular base station. Measurement of I and Q modulated waveforms in the time domain disclose the voltages which comprise the complex modulated waveform of a digital signal.

If installed, you may use PSA Option 122, the 80 MHz Bandwidth Digitizer hardware, or PSA Option 140, the 40 MHz Bandwidth Digitizer hardware to perform Waveform measurements of wideband signals using Basic Mode.

Configuring the Measurement System

The base station (BTS) under test has to be set to transmit the RF power remotely through the system controller. This transmitting signal is connected to the instruments RF input port. Connect the equipment as shown. An interfering or adjacent signal may supplied as shown.

From the base transmission station simulator (signal generator) and the system controller, set up a call using loopback mode for the MS to transmit the RF signal.

Figure 2-10 Waveform Measurement System

Making Measurements

42 Chapter 2

Making Measurements

Determining the RF Parameters of Your Signal

1. Using the appropriate cables, adapters, and circulator, connect the output signal of the BTS to the RF input of the instrument.

2. Connect the base transmission station simulator or signal generator to the BTS through a circulator to initiate a link constructed with sync and pilot channels, if required.

3. Connect a BNC cable between the 10 MHz OUT port of the signal generator and the EXT REF IN port of the instrument.

4. Connect the system controller to the BTS through the serial bus cable to control the BTS operation.

5. Connect an external trigger, if needed. Press

Mode Setup, Tr ig g e r to

access a menu to set up inputs and levels for all triggers. You must then select the appropriate trigger under the

Meas Setup, Trigger

menu to direct the measurement to use your trigger settings.

Setting the BTS From the mobile simulator (signal generator) and the system controller,

set up a call using loopback mode for the BTS to transmit the RF signal.

Measurement Procedure

Step 1. Press

Step 2. Press

Preset to preset the instrument.

MODE, Digital Modulation key to enable the Digital Modulation

Mode measurements.

Step 3. To set the measurement center frequency, press

FREQUENCY Channel

and enter a numerical frequency using the front-panel keypad. Complete the entry by selecting a units key, like

Step 4. Press

Press

Step 5. Press

The default display shows both

SPAN and enter a numerical span using the front-panel keypad. MHz to set the measurement span in MHz.

MEASURE to initiate the Waveform measurement.

Current (yellow trace) and Average (blue

MHz.

trace) data. To make viewing the display easier, you can view either the

Current or Average trace separately.

•Press display.

Step 6. Press

shown at a convenient time scale for viewing.

If installed, you may use the 80 MHz Bandwidth hardware to view a wideband signal in the RF Envelope view.

Press up to 80 MHz around your selected center frequency.

The following figure shows an example of an Waveform (Time Domain) measurement. The measured values for the

Chapter 2 43

Trace/View, Trace Display, and select the trace(s) desired for

SPAN X Scale, and the up or down arrow key until the waveform is

Making Measurements

SPAN and select the Wideband RF Path. Adjust the span to view

RF Envelope result for a

Making Measurements

Determining the RF Parameters of Your Signal

mean power and peak-to-mean power are shown in the text window.

Figure 2-11 Waveform Measurement - RF Envelope (Default View)

Step 7. Press

Trace/View to display the menu allowing selection of the other

Waveform views, including the following:

I/Q Waveform - Provides a view of the I and Q waveforms together on

• the same graph in parameters of voltage versus time in linear scale. Changes to the sweep time or resolution bandwidth can affect data acquisition.

Step 8. If PSA Option 140 or 122 is installed, you may use the 40 or 80 MHz

Bandwidth hardware to view a wideband signal in the Waveform view. Even if you are not interested in a wideband signal, using the Wideband IF path provides powerful measurement flexibility, including to the ability to accurately set practically any sample rate and thereby resample waveforms. Resampling, or oversampling, at the correct rate allows you to effectively obtain an integer number of samples per symbol. Make sure that the sample time is aligned with the decision points of the symbols to make analysis of measurement data much easier.

The following example of performing a Wideband IF Waveform measurement of a GSM burst will show the technique to accurately align and resample a signal:

•Press

Mode, and select Modulation Analysis to be able to use the 80

MHz IF path.

Making Measurements

•Press

44 Chapter 2

MEASURE, and select the Waveform measurement.

Determining the RF Parameters of Your Signal

•Press Trace/View and select the RF Envelope view.

Making Measurements

•Press

SPAN and toggle the IF Path key to select Wide. Adjust the span

to view up to 80 MHz around your selected center frequency. Note the example below has 1 million data points.

Figure 2-12 Waveform Measurement - RF Envelope View with Opt. 122− 80

MHz Bandwidth Digitizer Hardware

• Make sure that your samples are synchronized to the decision points of the signal of interest. In this case we will use the internal Frame Timer to trigger our measurement. A GSM frame is 4.615383 ms long.

Press

Mode Setup, Tri g g er, select Frame Timer, then select Period.

Enter 4.615383 ms. This only sets the frame timer period. You must direct the measurement to use the Frame Timer in the next step:

Press

Meas Setup, Trigge r S ource and select Frame.

For other measurements, an external trigger may be applied to an External Trigger Input, on either the front or the real panel. You must specify that trigger selection in this menu.

• In this example, we want to capture an entire GSM burst of 144 symbols (plus guard). A GSM burst is approximately 4.6 ms, so we will set our

Meas Time to 5 ms:

Making Measurements

Chapter 2 45

Making Measurements

Determining the RF Parameters of Your Signal

Press Meas Setup, Meas Time and enter 5 ms.

• In this resampling example, we want to take exactly 10 samples per GSM symbol. The GSM symbol rate is 270.833 kHz, so we want a sample rate of 2.70833 MHz. Option 122 Wideband IF hardware lets us set the desired sample rate, as follows: sample rate = 5/4 IF Bandwidth. That means we need set an IF BW of 2.16667 MHz.

Press

Meas Setup, IF BW and enter 2.16667 MHz.

You can also access the sample rate key directly:

Press

Rate

Meas Setup, Wideband Setup, Sample Rate. Enter the Sample

frequency. The Sample Rate and IF BW settings are coupled. The

5/4 ratio will be preserved regardless of which setting is used.

Figure 2-13 Waveform Measurement - RF Envelope View with Opt. 122−

80 MHz Bandwidth Digitizer Hardware

Making Measurements

For more details about making wideband measurements, see “PSA Option 122 Wideband Digitizer” in the Option 122 section in the “PSA Basic Mode Guide.”

Step 9. Press

waveforms are shown at a convenient voltage scale for viewing.

Step 10. Press

waveforms are shown at a convenient time scale for viewing.

46 Chapter 2

AMPLITUDE Y Scale and the up arrow or down arrow key until the

SPAN X Scale and the up arrow or down arrow key until the

Making Measurements

Determining the RF Parameters of Your Signal

Step 11. Press Marker, Tra ce, I/Q Waveform to activate a marker. Rotate the RPG

knob until the marker is shown at a desired time in the waveform for viewing the trace values at the time position of the marker.

Step 12. To make a measurement repeatedly, press

toggle to

Step 13. Press

Cont.

Meas Setup, More to check the keys available to change the

Meas Control, Measure and

measurement parameters from the default condition.

Using the Waveform Measurement to Set Up Triggering (for burst signals)

You can use the Waveform measurement to view your signal in the time domain and to help select the appropriate trigger to acquire your signal.

Step 1. Press

MEASURE, Waveform (Time Domain) to activate the Waveform

measurement view.

Step 2. Press

SPAN X Scale, Scale/Div to adjust the scale of the x-axis to view the

complete signal waveform. Use the front-panel keypad to input the

scale/div, then press a units key, like µs, to complete the entry.

Step 3. Press

Meas Setup, Trig Source, then select one of the available trigger

sources (free run is the default setting).

NOTE In the Waveform measurement, the Burst/Sync Search menu is not

available. measurement mode. must be used to trigger on framed signals in the

Burst/Sync Search is available in the Modulation Analysis

Frame Timer (located under the Trig Setup menu)

Waveform

measurement.

Step 4. Press

In the trigger mode, set the delay, peak level, and positive or negative edge slope trigger. You can also set up trigger holdoff, auto trigger timing, and frame timer settings.

For more details about using PSA Option 122, 80 MHz BW Digitizing Hardware, and PSA Option 140, 40 MHz Digitizing Hardware, including detailed function descriptions, SCPI commands, and concepts, see the PSA Basic Mode Guide.

Chapter 2 47

Trig, then choose a trigger mode to set up the trigger conditions.

Making Measurements

Modulation Analysis Measurements in 8 Steps

NOTE PSA Option 241 can analyze digital modulation for a single code

channel only. If multiple code channels are transmitted, synchronization will fail, and incorrect EVM results will be obtained. For modulation quality measurements of multiple code channels, Modulation Accuracy and Code Domain measurements must be performed by a full-featured standard-based personality, like PSA Option BAF for W-CDMA.

Step 1. Select the modulation analysis personality from the mode menu:

Press

MODE, Digital Modulation.

Step 2. Select the radio standard and device of your signal (if known):

Press Press

Selecting a radio standard will preset the

Mode Setup, Radio, Radio Standard, then select a radio format. Device, then select BTS or MS.

Meas Setup modulation

parameters to demodulate a standard radio signal.

Step 3. Activate the modulation analysis measurement:

Press

MEASURE, Modulation Analysis.

When you select Modulation Analysis, the PSA demodulates the radio standard, selected in Step 2, based off of the preset modulation parameters. If your signal has modulation properties that differ from the preset radio standards, follow steps 4 through 7 to modify the modulation parameters.

Step 4. Select a modulation format:

Press

Meas Setup, Demod, Modulation Format, then select the modulation

format of your signal from the available selections.

TIP If you do not know the modulation format of your signal, identifying an

unknown signal format is a significant challenge requiring specialized expertise. For more information on this subject see, “Modulation

Formats and Applications” on page 203.

Making Measurements

Step 5. Set the symbol rate of your signal:

Press to input a numerical rate, then press a units key, like

Meas Setup, Demod, Symbol Rate, then use the front-panel keypad

kHz, to complete

the entry.

Step 6. Select the measurement filter type, the reference filter type and the

filter roll-off (alpha) value:

48 Chapter 2

Making Measurements

Modulation Analysis Measurements in 8 Steps

Press Meas Setup, Demod, Meas Filter, then select a filter type. Press Press

Meas Setup, Demod, Ref Filter, then select a filter type. Meas Setup, Demod, Alpha/BT, then enter a numeric value.

When selecting the filter types, remember: the “measured” filter should simulate the intended receiver, while the “reference” filter should match the product of the transmitter and receiver filters.

TIP If the alpha/BT is unknown, you can make a starting estimate based on

the signal bandwidths as follows: (−60 dB BW / −3 dB BW) – 1.

EVM peaks between symbols mean an incorrect alpha, but won’t usually affect the EVM% readout (except in GSM). In the worst case, start with an alpha of 0.3 and manually adjust up or down for lowest intersymbol peaks.

Step 7. Select the measurement interval and the number of data points per

symbol for the measurement:

Press to input an interval in symbols, and press

Press

Meas Setup, Demod, Meas Interval, then use the front-panel keypad

Enter to complete the entry.

Display, Pts/Symbol, then select 1, 2, 4, 5, or 10 points per symbol.

More points/symbol reveal more detail of the intersymbol waveforms (for viewing eye diagrams, error peaks, etc.). The drawback of demodulating using more points/symbol is a slower measurement.

TIP Result length is important for bursted signals, as you do not want to

include data symbols taken before or after the burst (that is, you do not want to demodulate noise). See Concepts chapter for “PSA Digital

Demodulator” on page 281.

Step 8. Turn on Burst/Sync search for burst signals:

Press

Other burst search settings include

Length

TIP Maximum search length can be many times longer than a measurement

Meas Setup, Burst Sync/Search, Sync, then select a sync method.

Burst Search Threshold, Search

, Sync Pattern, Sync Word Length and Sync Offset.

length; set the search length to the burst “off” time plus twice the burst “on” time to insure that a complete burst will always be captured.

Making Measurements

NOTE The settings described in steps 5 through 8 are also available in a single

location. Press

Meas Setup, Meas Setup... to see all the measurement

settings.

Chapter 2 49

Making Measurements

Modulation Analysis Measurement Final Checks

• The EVM% result should be fairly consistent from measurement to measurement. Result peaks may indicate faulty triggering or incorrect synchronization.

• EVM vs. symbol trace should be noise-like, but fairly uniform (short peaks are OK). Abrupt changes within the EVM trace signify problems, as do sloping or V-shaped distributions.

• Overall shape of eye and constellation diagrams are regular and stable (even if individual symbols are very noisy, the characteristic shape should be evident). Eye opening should line up precisely with the display center line—if not, tweak “clock adjust” for best centering (lowest EVM). See “Setting Advanced Measurement Setup

Properties” on page 59 for more information on setting clock adjust.

• If measurement results are variable, and you suspect low signal-to-noise ratio is reducing your measurement accuracy, turn on the analyzer internal preamplifier:

Press

Input/Output, More (1 of 2), Int Preamp (On).

• You may also be able to optimize the dynamic range of the measurement by setting the RF input range as low as possible without overload:

Press

Meas Setup, More, Advanced, ADC Range, Manual then select the

highest ADC gain value that may used without tripping the Input Overload annunciator (at the lower edge of the spectrum display

screen).

Check: Increase ADC gain by 1 step; overload indicators should turn on. Finer adjustments can be made by setting the internal RF attenuation: you want to find the lowest ADC gain value that just trips the Input Overload annunciator. Use one 2 dB attenuator step lower than the attenuator setting that set the analyzer in overload.

Press

Input/Output, Input Atten and select the lowest attenuation

value that can be used without tripping the Input Overload annunciator.

Making Measurements

50 Chapter 2

Making Measurements

Modulation Analysis Measurement Final Checks

• If these methods do not improve the “noisy” characteristics of your measurement, you may need to supply more signal gain ahead of the RF input to the analyzer. Make sure you use the analyzer’s ability to correct for external gain and attenuation:

Press

Input/Output, Ext RF Atten and select either BTS or MS. You may

enter a positive number to correct for external attenuation or input a negative number to correct the power measurements for external gain.

NOTE When tuned above 3GHz, the PSA employs a YIG-tuned preselector

filter. This filter is required for full image protection, but it may be bypassed if Option 123 Unpreselected High Band hardware is installed. This option is especially useful when measuring band-limited signals in the absence of any other signals. If the Microwave Preselector is bypassed (OFF), then the IF frequency response at a given center frequency is repeatable. See “Microwave Preselector” on page 127.

Chapter 2 51

Making Measurements

Modifying Measurement Setup Parameters

Using the Measurement Setup Form

The measurement setup form contains demodulation parameters, averaging, triggering, burst/sync search parameters and equalization parameters. It is useful for a quick overview of all the key measurement settings without having to access each menu map individually to check or modify settings.

This procedure demonstrates how to navigate and modify settings in the measurement setup form. This procedure assumes you are already in the under the

Step 1. Access the measurement setup form:

Digital Modulation mode and you have selected Modulation Analysis

MEASURE menu.

Press

Meas Setup, Meas Setup...

Step 2. Navigate through the measurement setup settings:

Press

→ (right tab arrow), or ← (left tab arrow).

To modify the current settings, navigate to the parameter you want to modify with the left or right arrow keys. If the input box is highlighted in blue, you can use the soft key menu on the right of the display to select your setting. If the input box is highlighted in yellow, use the numeric keypad to enter a value and then select a unit key from the soft key menu.

Figure 2-14 Measurement Setup Form with Preset Values (Radio=W-CDMA)

Making Measurements

52 Chapter 2

If you are using a preset radio standard, the measurement settings are preset for your measurement. Modify the settings to match your modulation parameters or testing requirements.

Setting Demodulation Parameters

To demodulate customized digital formats, the demodulation parameters can be modified. Choose from a wide range of basic digital formats, measurement and reference filters, filter alpha/BT values and symbol rates. By modifying demodulation parameters to improve EVM, you can estimate what needs to be changed in your device under test to meet your test specifications.

The following procedure demonstrates how to modify demodulation parameters. This procedure assumes you are already in the

Modulation MEASURE menu.

Step 1. Access the demodulation menu:

mode and you have selected Modulation Analysis under the

Making Measurements

Modifying Measurement Setup Parameters

Digital

Press

Meas Setup, Demod.

Step 2. Select a modulation format:

Press

Modulation Format, then select a format.

Modulation formats include BPSK, QPSK, 8PSK, DQPSK, D8PSK, Pi/4 DQPSK, Offset QPSK, 16QAM, 32QAM, 64QAM, 128QAM, 256QAM, EDGE, 2FSK, 4FSK, 8FSK, MSK type1 and type2, DVB QAM 16, 32, 64, 128, and 256.

Step 3. Select a measurement filter type:

Press

Meas Filter, then select a filter type.

Filter types include root nyquist, nyquist, gaussian, EDGE measured filter (EMF), CDMA (IS-95 Base EQ), rectangle, and no filter.

Step 4. Select a reference filter type:

Press

Ref Filter, then select a filter type.

Filter types include root nyquist, nyquist, gaussian, EDGE and CDMA (IS-95 Base), rectangle, and half sine.

Making Measurements

Chapter 2 53

Making Measurements

Modifying Measurement Setup Parameters

Step 5. Enter a filter alpha/BT value:

Press

Alpha/BT, enter a numeric value, then press Enter.

Step 6. Enter a symbol rate:

Press

Symbol Rate, enter a numeric value, then select a unit.

Setting up a Trigger Source

For burst signals and TDMA (time division multiple access) signals, it is necessary to use a trigger for RF and modulation analysis of the signal.

For more detailed information on trigger types see “Measurement

Domains” on page 279.

This procedure reviews the available trigger source types. This procedure assumes you are already in the you have selected

Step 1. Access the trigger source menu:

Press

Meas Setup, Trigge r S ource.

Step 2. Select a trigger source from the list:

Free Run (Immediate) - Sets the trigger to start a new

• sweep/measurement as soon as the last one has ended (continuous sweep mode) or immediately (single sweep mode). Free run trigger is completely asynchronous to the RF or IF signal.

Modulation Analysis under the MEASURE menu.

Digital Modulation mode and

Making Measurements

Video (IF Envlp) - Activates the trigger condition that allows the next

• sweep to start if the detected RF envelope voltage crosses a level set by the video trigger level.

RF Burst (Wideband) - An internal wideband RF burst trigger that

• has an automatic level control for burst signals. It triggers on a level that is relative to the peak of the signal passed by the RF.

Ext Front - Sets the trigger to start a new sweep/measurement

• whenever the external voltage (connected to EXT TRIGGER INPUT on the front panel) passes through approximately 1.5 volts.

Ext Rear - Sets the trigger to start a new sweep/measurement

• whenever the external voltage (connected to TRIGGER IN on the rear panel) passes through approximately 1.5 volts.

Frame - Sets the trigger to use the internal frame clock to generate a

• trigger signal. The clock parameters are controlled in the Trig Setup menu (under the Mode Setup key).

54 Chapter 2

Making Measurements

Modifying Measurement Setup Parameters

Setting Burst/Sync Properties

Synchronization words (or patterns) are often used to resolve carrier phase ambiguity on non-differential modulation formats. It is important to realize that synchronization words are optional and are not necessary to achieve carrier locking.

Sync search lets you use a synchronization pattern to isolate a segment of your signal for display and analysis. The analyzer searches through demodulated data to find your synchronization pattern and then uses the

Sync Word Length to determine how many symbols to search as the

syncword.

Triggering is used to determine when the analyzer starts searching syncword or burst in data and analyzer stops searching.

Searching more detailed information on synchronization see “PSA

Digital Demodulator” on page 281.

This procedure demonstrates how to set burst/sync properties. This procedure assumes you are already in the you have selected

Modulation Analysis under the MEASURE menu.

Search Length determines when the

Digital Modulation mode and

Step 1. Access the synchronization menu:

Press

Meas Setup, Burst/Sync Search.

Step 2. Select the synchronization type:

Press

Available synchronization types include

Sync Word Burst and you have the option of selecting no sync type

(

Sync, then chose from one of the available sync types.

RF Ampl, Sync Word Cont,

None).

Step 3. Set the burst search threshold level for RF amplitude and sync word

burst synchronization types:

Press

Once the trigger requirements have been met and

Sync Word Burst is selected as a sync type, the burst must meet the

Burst Search Threshold, enter a numeric value, then press dB.

RF Ampl or

threshold level before the sync search starts. If the threshold level is met, the analyzer will demodulate the burst for the time period set in

Search Length.

Step 4. Set the length of time you want to search the burst or the

synchronization pattern:

Making Measurements

Press

Search Length, enter a numeric value, then select a unit, like ms.

Your trigger signal determines when the analyzer begins accumulating data for the search length. The analyzer begins to demodulate your signal when it receives a valid trigger, and capture data for the duration

Chapter 2 55

Making Measurements

Modifying Measurement Setup Parameters

of Search Length.

Step 5. Set the synchronization bit pattern in hexadecimal values:

Press press

Sync Pattern, enter a bit pattern as hexadecimal values, then

Done

The synchronization pattern is used when Sync Word Cont or

Sync Word Burst is enabled as a sync search type. Sync Pattern is not

used when

RF Ampl sync search type is enabled.

Step 6. Set the length of the synchronization word length:

Press

Sync Word Length determines how many symbols are used as SyncWord.

Sync Word Length, enter a numeric value, then press Enter.

See “Sync Word Length” on page 161 for word length settings. The Synchronization word length is used when

Sync Word Burst is enabled as a sync search type.

Sync Word Cont or

Step 7. Set the synchronization offset:

Press

Sync Offset, enter a numeric value, then press Enter.

Synchronization offset can be set from −1000 to 1000 symbols as described in “Sync Offset” on page 161. Synchronization offset determines the relative position of the measured data from the beginning of the SyncWord; with respect to the start of the sync pattern. Synchronization offset is used when

Sync Word Cont or Sync Word Burst

is enabled as a sync search type.

Making Measurements

Using Adaptive Equalization

Equalization removes linear errors from modulated signals by dynamically creating and applying a FIR (feed-forward) compensating filter. Using equalization allows measurement of impaired channels and can be used to isolate linear from non-linear error mechanisms. For more concept information on equalization see “Modulation quality

measurements” on page 286.

This procedure demonstrates how to setup the equalizer. This procedure assumes you are already in the you have selected

Step 1. Access the equalization menu:

Press

Meas Setup, More, Equalization.

Step 2. Set the equalization filter length:

Press

EQ Filter Length, enter a numeric value, then press Enter.

Available filter length values include 3, 5, 7 and 99 symbols.

When selecting a filter length, the best filter length is the smallest that

Modulation Analysis under the MEASURE menu.

Digital Modulation mode and

56 Chapter 2

meets your measurement requirements. For example, measurements at the transmitter may only need a few symbols in length. Measurements in multi-path environments require longer filter lengths.

Step 3. Set the equalization convergence:

Making Measurements

Modifying Measurement Setup Parameters

Press

EQ Convergence, enter a numeric value, then press Enter.

You can set convergence values from 0.001 to 100.

Convergence determines how quickly the equalization filter coefficients converge to the estimated values for each measurement. Larger values converge faster. Values set too large can cause the adaption algorithm to become unstable, limiting the minimum EVM or SNR.

TIP At the start of your measurement set the convergence high, to quickly

shape the filter. Then decrease the convergence to fine-tune the filter to the optimum shape to get the best EVM results.

Step 4. Turn the equalization filter on:

Press

EQ Filter (On).

When equalization is first enabled, the equalization filter has a unit impulse response. The length of the filter determines the position of the unit impulse response in the filter. The impulse is located in the center of the filter for short filter lengths. As the filter length increases, the impulse moves, proportionally, towards the start of the filter to handle channels with large delay-spread.

The equalization filter has a unit response when you:

• First run the equalizer.

• Reset the equalizer filter

• Change points/symbol

• Change the measured or reference filter

• Change the symbol rate

• Change the clock delay adjustment

• Change the equalizer filter length

• Change the modulation format

•Preset the mode

Aside from the above conditions, the equalizer uses the last computed filter coefficients when you enable equalization. For example, if you used equalization in a previous measurement, the coefficients from the previous measurement are used, unless you reset the equalization filter (or change one of the settings as mentioned in the above list). It is good

Making Measurements

Chapter 2 57

Making Measurements

Modifying Measurement Setup Parameters

practice to reset the equalization filter to initialize the filter coefficients before starting the measurement.

Step 5. Reset the equalization filter:

Press

Reset EQ Filter. Once you reach the desired EVM results after

resetting the equalization filter, hold the filter coefficient values.

Step 6. Hold the filter coefficient values:

Press

EQ Hold (On). When EQ Hold is on, the analyzer does not update

the filter coefficients. Instead, the analyzer uses the last updated coefficients before selecting hold.

When

EQ Hold is off, the analyzer uses the results of the current

measurement to update the filter coefficients for the next measurement. The equalization algorithm chooses coefficients that produce a modulation quality result that is less impacted by the presence of linear distortion.

Step 7. You can view the equalizer graphically:

Press

Trace/View, Equalizer (Quad View). The Ch Frequency Response

trace shows the frequency response channel for which the equalizer is correcting. Ch Frequency Response is computed as the inverse of the equalization filter's frequency response. The data is complex and is normally displayed in units of magnitude and phase.

The Eq Impulse Response trace shows the impulse response of the equalization filter. The example shown in Figure 2-15 is an EDGE signal.

Making Measurements

58 Chapter 2

Modifying Measurement Setup Parameters

Figure 2-15 Equalizer View - EDGE Signal Example

Making Measurements

Setting Advanced Measurement Setup Properties

Advanced measurement features give you additional flexibility in setting measurement limits, adjusting the clock, setting the IF bandwidth and setting the analyzer ADC range.

This procedure demonstrates how to set advanced measurement properties. You can jump from step 1 to any other step in this procedure if you need to access a certain advanced setting. This procedure assumes you are already in the selected

Modulation Analysis under the MEASURE menu.

Step 1. Access the advanced measurement menu:

Press

Meas Setup, More, Advanced.

Step 2. Modify the pass/fail limit for RMS EVM:

Press

Limits, RMS EVM, enter a numeric value, then press %.

When you enter a numeric value the limit turns on automatically. To toggle the limit off and on press

Step 3. Modify the pass/fail limit for frequency error:

Press terminator, like

Limits, Freq Error, enter a numeric value, then select a unit

kHz.

Digital Modulation mode and you have

RMS EVM.

Making Measurements

When you enter a numeric value the limit turns on automatically. To

Chapter 2 59

Making Measurements

Modifying Measurement Setup Parameters

toggle the limit off and on press Freq Error.

Step 4. Mirror (invert) the frequency spectrum about the analyzer center

frequency for correct demodulation:

Press

By pressing

Spectrum (Invert).

Spectrum you can toggle the frequency spectrum between

normal and inverted. The default spectrum setting is Normal.

Often, when a signal is mixed down from a higher frequency, the spectrum is flipped or mirrored about the center frequency as a result of the mixing scheme used. A mirror spectrum occurs when the frequency of the mixer’s LO is higher than the frequency of the signal being measured.

Step 5. Modify clock adjust (in symbols) to determine when the demodulator

samples the I/Q trajectory:

Press

Clock Adjust, enter a numeric value, then press Enter.

Clock adjust can be set from −0.5 to +0.5 symbols. Zero (0) symbols is the default value.

Some digital communications systems contain non-linearity’s that can bias the digital demodulator’s estimation of the symbol clock position. Use clock adjust to compensate for this offset and obtain a lower EVM.

You can see the effects of changing clock adjust by displaying a constellation diagram or eye diagram. Increasing (or decreasing) clock adjust:

Making Measurements

• Shifts the detection-decision points in the constellation diagram.

• Slides the eye diagram right or left (remember that in the eye diagram, the symbol locations remain in a fixed location on the display; therefore, changing the location of symbols has the effect of horizontally shifting of the eye diagram).

60 Chapter 2

Making Measurements

Modifying Measurement Setup Parameters

Step 6. Toggle the EVM reference calculation between mean and max:

Press

EVM Ref Calc.

The EVM reference calculation is available when demodulating one of the QAM formats. When

EVM Ref Calc is set to mean, the mean

magnitude of all QAM decision points are used as the reference. When it is set to max, the magnitude of the decision points with the largest distance from the origin are used as a reference.

Step 7. Modify the IF bandwidth setting:

Press like

IF Bandwidth (Man), enter a numeric value, then select a unit key,

MHz. For the optimum EVM accuracy, IF Bandwidth should

encompass all the significant power spectral density of the channel.

If installed, PSA Option 122, 80 MHz Bandwidth Digitizer hardware may be used to capture up to 80 MHz of signal spectrum. Press

Setup

, More, IF Path, and toggle the setting to Wide to increase the available IF bandwidth of the instrument. See “Wideband Setup” on

page 171 for more details of using the wideband IF path.

The default state is set to auto. If no radio standard is selected, the default setting is 10 MHz. The maximum setting is 10 MHz and the minimum setting is 1 kHz.

When the

IF Bandwidth is set to auto, the IF bandwidth is determined

based on the radio standard format and symbol rate (IF Bandwidth = symbol rate x 4).

Meas

Step 8. Select an ADC ranging method:

Press

The

Peak

•

ADC Range, then select an ADC range type.

ADC Range default is set to Auto. You can select from Auto, Auto

, AutoPeakLock and Manual:

Auto - Select this to set the ADC range automatically.

Auto Peak - Select this to set the ADC range automatically to the

peak signal level. Auto peak is a compromise that works well for both CW and burst signals.

AutoPeakLock - Select this to hold the ADC range to the peak signal

•

level.

Manual - Select from one of the following ADC range levels: 0 dB, +6

•

, +12 dB, +18 dB or None. Select None to lock the range at the

present value. Manual range settings provides the best measurement results for CW signals.

Making Measurements

Chapter 2 61

Making Measurements

Measuring Digital Modulation Formats

Modulation Analysis Measurement Views

To help pin-point modulation problems, the modulation analysis personality provides I/Q polar graphs, EVM versus time graphs, eye diagrams and numeric results tables. The following procedures show you how to navigate through the results displays using a W-CDMA signal (Bluetooth is used for the FSK displays).

• “Setting up the Modulation Analysis Personality” on page 63

• “Viewing the I/Q Polar Vector and Constellation Graphs” on page 64

• “Viewing the Numeric Measurement Results” on page 66

• “Viewing the I/Q Error (Quad-View) Results” on page 67

• “Viewing the Magnitude Error Versus Time Results” on page 68

• “Viewing the Phase Error Versus Time Results” on page 70

• “Viewing the EVM Versus Time Results” on page 73

• “Viewing the Eye Diagram Results” on page 75

• “Viewing the FSK Error (Quad-View) Results” on page 77

• “Viewing the FSK Error Versus Time Results” on page 79

• “Viewing the FSK Error Spectrum Results” on page 81

• “Viewing the FSK Measured Time Results” on page 83

Modulation Analysis Examples

The following examples analyze industry standard wireless communication signals for each family of the basic digital modulation formats.

• “PSK Modulation Analysis (cdma2000 QPSK Example)” on page 85

• “QAM Modulation Analysis (64QAM Example)” on page 87

• “EDGE Modulation Analysis” on page 89

• “FSK Modulation Analysis (Bluetooth 2FSK Example)” on page 91

• “MSK Modulation Analysis (GSM MSK type 1 Example)” on page 93

For a list of all available basic digital formats and pre-set radio standard formats see “Digital Modulation Format Standards” on

page 203.

Making Measurements

62 Chapter 2

Making Measurements

Measuring Digital Modulation Formats

Setting up the Modulation Analysis Personality

This procedure is the first step toward making any measurements with the modulation analysis personality.

Configuring the Measurement System

Refer to “Configuring a BTS Measurement System” on page 29 to connect the measurement equipment.

Agilent ESG Series Vector Signal Generator Settings

Radio Standard: W-CDMA (3GPP) Link: Forward Active channel: 1 DPCH (data channel) Frequency: 1 GHz Power (Signal Amplitude): -20 dBm Modulation: QPSK Filter: WCDMA, 0.22 alpha Symbol rate: 3.84 Msps

Measurement Procedure

If you have a problem, and get an error message, see “Interpreting

Error Codes” on page 119.

Step 1. Preset the instrument and select the digital modulation personality:

Press Press

Preset, Factory Preset (if available). MODE, Digital Modulation.

Step 2. Select the W-CDMA pre-set radio standard and base station device:

Press Press

Mode Setup, Radio, Radio Standard, WCDMA. Device (BTS), to underline BTS.

Step 3. Set the center frequency to 1 GHz.

Press

FREQUENCY Channel, Center Freq, 1, GHz.

Step 4. Enable the modulation analysis mode to measure and display EVM and

other modulation metrics.

Press

MEASURE, Modulation Analysis.

The default view for the modulation analysis personality is the I/Q Measured Polar Vector graph (see Figure 2-16).

Making Measurements

Chapter 2 63

Making Measurements

Measuring Digital Modulation Formats

Viewing the I/Q Polar Vector and Constellation Graphs

This procedure demonstrates the different views of the I/Q measured polar graphs. The I/Q polar graphs can show symbol point trajectories (inter-symbol data) and constellation points at the same time or individually. A common example of viewing the vector (inter-symbol) data is to determine if the filter roll-off value (alpha) is set too steep or shallow as shown by the length of the trajectory past the symbol point.

Measurement Procedure

If you have a problem, and get an error message, see “Interpreting

Error Codes” on page 119.

Step 1. Follow the procedure “Setting up the Modulation Analysis Personality”

on page 63 before continuing.

Step 2. View the I/Q measured polar graph with vector data and constellation

points (this is the default view):

Press

Trace/View, I/Q Measured Polar Graph.

The default view for the modulation analysis personality is the I/Q Measured Polar Vector graph (see Figure 2-16). The measurement

values for EVM, magnitude error, phase error, frequency error, I/Q offset and rho are shown in the summary window on the left side of the display.

Figure 2-16 I/Q Measured Polar Vector Graph (Default View)

Making Measurements

64 Chapter 2

Measuring Digital Modulation Formats

Step 3. View the I/Q measured polar graph with vector (inter-symbol data) or

constellation points only. Press Vec tor da t a ( Figure 2-17). Press

Display, I/Q Polar Type, Vector to see

Display, I/Q Polar Type, Constellation to

see Constellation data (Figure 2-17).

Figure 2-17 I/Q Measured Polar Graph - Polar Vector View

Making Measurements

Figure 2-18 I/Q Measured Polar Graph (Left - Vector, Right - Constellation)

Making Measurements

Chapter 2 65

Making Measurements

Measuring Digital Modulation Formats

Viewing the Numeric Measurement Results

The numeric results provide you with the most important modulation results to determine where the problem might lie. It’s a good starting point to compare results side-by-side and decide which measurement view to go to next.

Measurement Procedure

If you have a problem, and get an error message, see “Interpreting

Error Codes” on page 119.

Step 1. Follow the procedure “Setting up the Modulation Analysis Personality”

on page 63 before continuing

Step 2. Select the numeric results view:

Press

Trace/View, Numeric Results.

Figure 2-19 Numeric Results View (QPSK Example)

Making Measurements

The numeric results summary table shows modulation data including maximum and average values for EVM, magnitude error, phase error, frequency error, I/Q offset, quadrature skew, I/Q gain imbalance, SNR and Rho.

NOTE The numeric result types differ between modulation formats. For

example, FSK results don’t provide phase results. See “FSK Modulation

Analysis (Bluetooth 2FSK Example)” on page 91 for more information.

66 Chapter 2

Making Measurements

Measuring Digital Modulation Formats

Viewing the I/Q Error (Quad-View) Results

This procedure demonstrates the different views of the I/Q error quad-view. The I/Q error quad-view allows you to see the magnitude error versus time, phase error versus time, EVM versus time and a numeric summary table all on one screen to quickly determine any impairments that may exist. You can zoom in on each of the 4 views for more resolution to help pin-point any problems.

If you have a problem, and get an error message, see “Interpreting

Error Codes” on page 119.

Step 1. Follow the procedure “Setting up the Modulation Analysis Personality”

on page 63 before continuing.

Step 2. View the I/Q error quad-view:

Press

Trace/View, I/Q Error (Quad-View).

Figure 2-20 I/Q Error (Quad-View)

The I/Q error quad-view measurement result displays three graphs and one numeric results summary table. The graphs consist of Mag Error versus symbol, Phase Error versus symbol and EVM versus symbol. The numerical results table shows key modulation metrics as maximum and average values associated with the last demodulated capture period.

NOTE Using the Next Window key, you can scroll through the measurement

displays, where the current selection is highlighted with a green box outline. The

Zoom key will zoom in on the currently selected display. To

go back to the quad-view display press Zoom again.

Chapter 2 67

Making Measurements

Measuring Digital Modulation Formats

Viewing the Magnitude Error Versus Time Results

This procedure shows you how to adjust x-axis and y-axis settings for the magnitude error versus time graph. By zooming into a time capture area of interest, modulation magnitude errors can be identified easier.

If you have a problem, and get an error message, see “Interpreting

Error Codes” on page 119.

Step 1. Follow the procedure “Setting up the Modulation Analysis Personality”

on page 63 before continuing.

Step 2. View the I/Q error quad-view (see Figure 2-20):

Press

Trace/View, I/Q Error (Quad-View).

Step 3. View the zoomed-in graph of magnitude error versus symbol. Use

markers to look at the magnitude error of individual symbol points.

Press Press

NOTE Using the Next Window key, you can scroll through the measurement

Zoom. Marker, Trace, Mag Error.

displays, where the current selection is highlighted with a green box outline. The

Zoom key will zoom in on the currently selected display. To

go back to the quad-view display press Zoom again.

Figure 2-21 I/Q Error: Magnitude Error versus Symbol

Making Measurements

The Mag Error measurement display shows the magnitude error versus symbol. Depending on the number of symbols captured in the

Meas Interval key, by measurement default parameters, the x-axis

displays symbols 0 through 1 minus the

68 Chapter 2

Meas Interval

Making Measurements

Measuring Digital Modulation Formats

Step 4. Change the x-axis settings to zoom in on smaller portion of the

measurement capture interval:

Press

SPAN X Scale, Scale/Div, 3, Symbols.

To place the symbol points on the vertical graticules, use integer symbol values for reduce the measurement interval with the to view another portion of the time capture interval, adjust the

Val ue

Scale/Div. An alternate method to view less symbols is to

Meas Interval key. If you want

Ref

Figure 2-22 I/Q Error: Magnitude Error versus Symbol (X-Axis Settings)

The Mag Error measurement displayed in Figure 2-22 shows an x-axis

Scale/Div of 3 with a measurement capture interval of 256 symbols.

Step 5. Decrease the y-axis settings to increase the resolution of the magnitude

error results. Use the same x-axis settings from the previous step.

Press

AMPLITUDE Y Scale, Scale/Div, 0.4, %.

Figure 2-23 I/Q Error: Magnitude Error versus Symbol (Y-Axis Settings)

The Mag Error measurement displayed in Figure 2-23 shows a y-axis

Scale/Div

of 0.4 percent and a reference level of 0 percent.

Making Measurements

Chapter 2 69

Making Measurements

Measuring Digital Modulation Formats

Viewing the Phase Error Versus Time Results

This procedure shows you how to adjust x-axis and y-axis settings for the phase error versus time graph. By zooming into a time capture area of interest, modulation phase errors can be identified easier.

If you have a problem, and get an error message, see “Interpreting

Error Codes” on page 119.

Step 1. Follow the procedure “Setting up the Modulation Analysis Personality”

on page 63 before continuing.

Step 2. View the I/Q error quad-view (see Figure 2-20):

Press

Trace/View, I/Q Error (Quad-View).

Step 3. View the zoomed in graph of phase error versus symbol. Use markers to

look at the phase error of individual symbol points.

Press Press Press

NOTE Using the Next Window key, you can scroll through the measurement

Next Window until the Phase Error window is selected. Zoom. Marker, Trace, Phase Error.

displays, where the current selection is highlighted with a green box outline. The

Zoom key will zoom in on the currently selected display. To

go back to the quad-view display press Zoom again.

Figure 2-24 I/Q Error: Phase Error versus Symbol

Making Measurements

The Phase Error measurement display shows the phase error versus symbol. Depending on the number of symbols captured in the

Interval

symbols 0 through 1 minus the

70 Chapter 2

key, by measurement default parameters, the x-axis displays

Meas Interval

Meas

Making Measurements

Measuring Digital Modulation Formats

Step 4. Change the x-axis settings to zoom in on smaller portion of the

measurement capture interval:

Press

SPAN X Scale, Scale/Div, 3, Symbols.

To place the symbol points on the vertical graticules, use integer symbol values for reduce the measurement interval with the

Scale/Div. An alternate method to view less symbols is to

Meas Interval key. If you want

to view another portion of the time capture interval, adjust the

Val ue

Figure 2-25 I/Q Error: Phase Error versus Symbol (X-Axis Settings)

The Phase Error measurement displayed in Figure 2-25 shows an x-axis

Scale/Div of 3 with a measurement capture interval of 256

symbols.

Ref

Step 5. Decrease the y-axis settings to increase the resolution of the phase

error results. Use the same x-axis settings from the previous step.

Press

AMPLITUDE Y Scale, Scale/Div, 20, Degrees.

Figure 2-26 I/Q Error: Phase Error versus Symbol (Y-Axis Settings)

The Phase Error measurement displayed in Figure 2-26 shows a y-axis

Making Measurements

Chapter 2 71

Making Measurements

Measuring Digital Modulation Formats

Scale/Div of 20 degrees and a reference level of 0 degrees.

Making Measurements

72 Chapter 2

Making Measurements

Measuring Digital Modulation Formats

Viewing the EVM Versus Time Results

This procedure shows you how to adjust x-axis and y-axis settings for the EVM versus time graph. By zooming into a time capture area of interest, EVM results can be analyzed at the symbol level.

If you have a problem, and get an error message, see “Interpreting

Error Codes” on page 119.

Step 1. Follow the procedure “Setting up the Modulation Analysis Personality”

on page 63 before continuing.

Step 2. View the I/Q error quad-view (see Figure 2-20):

Press

Trace/View, I/Q Error (Quad-View).

Step 3. View the zoomed in graph of EVM versus symbol. Use markers to look

at the EVM of individual symbol points.

Press Press Press

NOTE Using the Next Window key, you can scroll through the measurement

Next Window until the EVM window is selected. Zoom. Marker, Trace, EVM.

displays, where the current selection is highlighted with a green box outline. The

Zoom key will zoom in on the currently selected display. To

go back to the quad-view display press Zoom again.

Figure 2-27 I/Q Error: EVM versus Symbol

The EVM measurement display shows EVM versus symbol. Depending on the number of symbols captured in the

Meas Interval key, by

measurement default parameters, the x-axis displays symbols 0 through 1 minus the

Chapter 2 73

Meas Interval

Making Measurements

Measuring Digital Modulation Formats

Step 4. Change the x-axis settings to zoom in on smaller portion of the

measurement capture interval:

Press

SPAN X Scale, Scale/Div, 3, Symbols.

To place the symbol points on the vertical graticules, use integer symbol values for reduce the measurement interval with the

Scale/Div. An alternate method to view less symbols is to

Meas Interval key. If you want

to view another portion of the time capture interval, adjust the

Val ue

Figure 2-28 I/Q Error: EVM versus Symbol (X-Axis Settings)

The EVM measurement displayed in Figure 2-28 shows an x-axis

Scale/Div of 3 with a measurement capture interval of 256 symbols.

Ref

Making Measurements

Step 5. Decrease the y-axis settings to increase the resolution of the phase

error results. Use the same x-axis settings from the previous step.

Press

AMPLITUDE Y Scale, Scale/Div, 0.3, %.

Figure 2-29 I/Q Error: EVM versus Symbol (Y-Axis Settings)

The EVM measurement displayed in Figure 2-29 shows a y-axis

Scale/Div

of 0.3 percent and a reference level of 0 percent.

74 Chapter 2

Making Measurements

Measuring Digital Modulation Formats

Viewing the Eye Diagram Results

This procedure demonstrates the different views of the eye quad-view. The eye quad-view allows you to view the eye I diagram, the eye Q diagram, I/Q measured polar vector graph and a numeric results summary table all on one screen to quickly determine any impairments that may exist. You can zoom in on each of the 4 views for more resolution to help pin-point any problems.

If you have a problem, and get an error message, see “Interpreting

Error Codes” on page 119.

Step 1. Follow the procedure “Setting up the Modulation Analysis Personality”

on page 63 before continuing.

Step 2. View the eye graphical results on a quad-view display.

Press

Trace/View, Eye (Quad-View).

Figure 2-30 Eye (Quad-View)

The eye quad-view measurement result displays two eye diagrams (I and Q). The I and Q eye diagrams show the transitions of constellation points of the QPSK signal. The eye diagrams are a continuous plot of the symbol transitions. The eye diagram has three symbol transitions, where the third symbol transition wraps around to the start of the eye diagram (first symbol point on the eye diagram).

Step 3. View the zoomed in eye I diagram. Make sure the green outline is

highlighting the eye I diagram and zoom into the diagram.

Press

NOTE Using the Next Window key, you can scroll through the measurement

Zoom.

displays, where the current selection is highlighted with a green box outline. The

Zoom key will zoom in on the currently selected display. To

go back to the quad-view display press Zoom again.

Chapter 2 75

Making Measurements

Measuring Digital Modulation Formats

Figure 2-31 Eye I Diagram

The Eye I Diagram shows the symbol transitions of the baseband I data. The Eye Q diagram is identical to the Eye I diagram except the symbol data from Q is offset 90 degrees from I.

Step 4. Change the scaling of the eye diagram:

Press

AMPLITUDE Y Scale, Scale/Div.

Rotate front-panel knob clockwise to increase the scale/div value.

Step 5. Pause the measurement and build the eye diagram symbol-by-symbol:

Press Press

Meas Control, Pause. Display, I/Q Points, 0, Enter.

Rotate front-panel knob clockwise to add symbol points.

Figure 2-32 Eye I Diagram - Building Symbol-by-Symbol

Making Measurements

In Figure 2-32, the first 5 symbols are plotted, starting with symbol 1 on the far left-side of the diagram.

NOTE The I/Q measured polar vector graph can be built the same way.

Press Meas Control, Resume to continue.

76 Chapter 2

Making Measurements

Measuring Digital Modulation Formats

Viewing the FSK Error (Quad-View) Results

This procedure demonstrates the FSK error quad-view display. The FSK error quad-view allows you to see the FSK error versus time, FSK error spectrum, FSK measured time and a numeric summary table all on one screen to quickly determine any impairments that may exist. You can zoom in on each of the 4 views for more resolution to help pin-point any problems.

NOTE In this procedure, a bursted Bluetooth 2-level FSK signal is used with a

symbol rate of 1 Msps, and a filter alpha of 0.5 at 1 GHz.

If you have a problem, and get an error message, see “Interpreting

Error Codes” on page 119.

Step 1. Preset the instrument and select the digital modulation personality:

Press Press

Preset, Factory Preset (if available). MODE, Digital Modulation.

Step 2. Select the Bluetooth pre-set radio standard and base station device:

Press Press

Mode Setup, Radio, Radio Standard, More, Bluetooth. Device (BTS), to underline BTS.

Step 3. Set the center frequency to 1 GHz.

Press

FREQUENCY Channel, Center Freq, 1, GHz.

Step 4. Enable the modulation analysis mode to measure and display EVM and

other modulation metrics.

Press

MEASURE, Modulation Analysis.

Step 5. Set the trigger source to capture the burst:

Press Press

Meas Setup, Trig Source, RF Burst (Wideband). Meas Control, Restart.

Figure 2-33 I/Q Measured Polar Graph

Chapter 2 77

Making Measurements

Measuring Digital Modulation Formats

The default view for the modulation analysis personality is the I/Q Measured Polar Vector graph (see Figure 2-33).

Step 6. View the FSK error quad-view:

Press

Trace/View, FSK Error (Quad-View).

Figure 2-34 FSK Error (Quad-View)

The FSK error quad-view measurement result displays three graphs and one numeric results summary table. The graphs consist of FSK Error versus symbol, FSK Error Spectrum and FSK Meas Time. The numerical results table shows key modulation metrics as maximum and average values associated with the last demodulated capture period.

Making Measurements

NOTE Using the Next Window key, you can scroll through the measurement

displays, where the current selection is highlighted with a green box outline. The

Zoom key will zoom in on the currently selected display. To

go back to the quad-view display press Zoom again.

78 Chapter 2

Making Measurements

Measuring Digital Modulation Formats

Viewing the FSK Error Versus Time Results

This procedure shows you how to adjust x-axis and y-axis settings for the FSK error versus time graph. By zooming into a time capture area of interest, the FSK error results can be analyzed at the symbol level.

NOTE In this procedure, a bursted Bluetooth 2-level FSK signal is used with a

symbol rate of 1 Msps, and a filter alpha of 0.5 at 1 GHz.

If you have a problem, and get an error message, see “Interpreting

Error Codes” on page 119.

Step 1. Follow steps 1 through 5 in the procedure “Viewing the FSK Error

(Quad-View) Results” on page 77 before continuing.

Step 2. View the FSK error quad-view (see Figure 2-34):

Press

Trace/View, FSK Error (Quad-View).

Step 3. View the zoomed in graph of FSK error versus symbol. Use markers to

look at the error of individual symbol points.

Press Press

Zoom. Marker, Trace, FSK Error. then use the numeric keypad or

front-panel knob to place the marker on a symbol.

NOTE Using the Next Window key, you can scroll through the measurement

displays, where the current selection is highlighted with a green box outline. The

Zoom key will zoom in on the currently selected display. To

go back to the quad-view display press Zoom again.

Figure 2-35 FSK Error versus Symbol

The FSK error measurement display shows FSK error versus symbol. Depending on the number of symbols captured in the

Meas Interval key,

by measurement default parameters, the x-axis displays symbols 0 through 1 minus the

Chapter 2 79

Meas Interval

Making Measurements

Measuring Digital Modulation Formats

Step 4. Change the x-axis settings to zoom in on smaller portion of the

measurement capture interval:

Press

SPAN X Scale, Scale/Div, 3, Symbols.

To place the symbol points on the vertical graticules, use integer symbol values for reduce the measurement interval with the

Scale/Div. An alternate method to view less symbols is to

Meas Interval key. If you want

to view another portion of the time capture interval, adjust the

Val ue

Figure 2-36 FSK Error versus Symbol (X-Axis Settings)

Ref

Making Measurements

The FSK error measurement displayed in Figure 2-36 shows an x-axis

Scale/Div of 3 with a measurement capture interval of 256 symbols.

Step 5. Decrease the y-axis settings to increase the resolution of the FSK error

results. Use the same x-axis settings from the previous step.

Press

AMPLITUDE Y Scale, Scale/Div, 0.2, %.

Figure 2-37 FSK Error versus Symbol (Y-Axis Settings)

The FSK Error measurement displayed in Figure 2-37 shows a y-axis

Scale/Div

of 0.2 percent and a reference level of 0 percent.

80 Chapter 2

Making Measurements

Measuring Digital Modulation Formats

Viewing the FSK Error Spectrum Results

This procedure shows you how to adjust x-axis and y-axis settings for the FSK error spectrum graph.

NOTE In this procedure, a bursted Bluetooth 2-level FSK signal is used with a

symbol rate of 1 Msps, and a filter alpha of 0.5 at 1 GHz.

If you have a problem, and get an error message, see “Interpreting

Error Codes” on page 119.

Step 1. Follow steps 1 through 5 in the procedure “Viewing the FSK Error

(Quad-View) Results” on page 77 before continuing.

Step 2. View the FSK error quad-view (see Figure 2-34):

Press

Trace/View, FSK Error (Quad-View).

Step 3. View the zoomed in graph of FSK error spectrum. Use markers to look

at frequency points of the error spectrum.

Press Press Press

Next Window until the FSK error spectrum graph is selected. Zoom. Marker, Trace , FSK Error Spectrum, then use the numeric keypad or

front-panel knob to place the marker on a frequency point.

NOTE Using the Next Window key, you can scroll through the measurement

displays, where the current selection is highlighted with a green box outline. The

Zoom key will zoom in on the currently selected display. To

go back to the quad-view display press Zoom again.

Figure 2-38 FSK Error Spectrum

When you select FSK error spectrum, the analyzer displays the spectrum of FSK error versus time. In other words, the analyzer derives the FSK error time trace, and then windows and FFTs this trace to produce the FSK error spectrum trace.

Chapter 2 81

Making Measurements

Measuring Digital Modulation Formats

Step 4. Change the x-axis settings to zoom in on smaller portion of the error

spectrum:

Press

SPAN X Scale, Scale/Div, 20, kHz.

Figure 2-39 FSK Error Spectrum (X-Axis Settings)

The FSK Error Spectrum measurement displayed in Figure 2-39 shows an x-axis

Scale/Div of 20 kHz.

Step 5. Decrease the y-axis settings to increase the resolution of the FSK error

spectrum results. Use the same x-axis settings from the previous step.

Press

AMPLITUDE Y Scale, Scale/Div, 5, dB.

Making Measurements

Figure 2-40 FSK Error Spectrum (Y-Axis Settings)

The FSK Error Spectrum measurement displayed in Figure 2-40 shows a y-axis

Scale/Div of 5 dB and a reference level of −7.5 dB.

82 Chapter 2

Making Measurements

Measuring Digital Modulation Formats

Viewing the FSK Measured Time Results

This procedure shows you how to adjust x-axis and y-axis settings for the FSK measured time graph.

NOTE In this procedure, a bursted Bluetooth 2-level FSK signal is used with a

symbol rate of 1 Msps, and a filter alpha of 0.5 at 1 GHz.

If you have a problem, and get an error message, see “Interpreting

Error Codes” on page 119.

Step 1. Follow steps 1 through 5 in the procedure “Viewing the FSK Error

(Quad-View) Results” on page 77 before continuing.

Step 2. View the FSK error quad-view (see Figure 2-34):

Press

Trace/View, FSK Error (Quad-View).

Step 3. View the zoomed in graph of FSK measured time. Use markers to look

at the measured symbol points.

Press Press Press

Next Window until the FSK measured time graph is selected. Zoom. Marker, Trace, FSK Measured, then use the numeric keypad or

front-panel knob to place the marker on a symbol.

NOTE Using the Next Window key, you can scroll through the measurement

displays, where the current selection is highlighted with a green box outline. The

Zoom key will zoom in on the currently selected display. To

go back to the quad-view display press Zoom again.

Figure 2-41 FSK Measured Time

The FSK measured time display shows the symbol decision points versus time. Depending on the number of symbols captured in the

Interval

symbols 0 through 1 minus the

Chapter 2 83

key, by measurement default parameters, the x-axis displays

Meas Interval

Meas

Making Measurements

Measuring Digital Modulation Formats

Step 4. Change the x-axis settings to zoom in on smaller portion of the

measurement capture interval:

Press

SPAN X Scale, Scale/Div, 3, Symbols.

To place the symbol points on the vertical graticules, use integer symbol values for

Scale/Div. An alternate method to view less symbols is to

reduce the measurement interval with the to view another portion of the time capture interval, adjust the

Val ue

Figure 2-42 FSK Measured Time (X-Axis Settings)

Meas Interval key. If you want

Ref

Making Measurements

The FSK Meas Time display in Figure 2-42 shows an x-axis 3 symbols per division with a measurement interval of 320 symbols.

Step 5. Increase the y-axis settings to observe how y-axis scaling works. Use

the same x-axis settings from the previous step.

Press

AMPLITUDE Y Scale, Scale/Div, 0.3, Enter.

Figure 2-43 FSK Measured Time (Y-Axis Settings)

The FSK Measured Time display in Figure 2-43 shows a y-axis of 0.3 and a reference value of 0.

Scale/Div of

Scale/Div

84 Chapter 2

Making Measurements

Measuring Digital Modulation Formats

PSK Modulation Analysis (cdma2000 QPSK Example)

Supported PSK formats: BPSK, QPSK, 8PSK, DQPSK, D8PSK, Pi/4 DQPSK and Offset QPSK.

This section explains how to demodulate and analyze a cdma2000 signal (pilot channel only) at 1 GHz and −10 dBm. This measurement procedure guides you through the different measurement views useful for modulation analysis.

Configuring the Measurement System

Refer to “Configuring a BTS Measurement System” on page 29 to connect the measurement equipment.

Measurement Procedure

If you have a problem, and get an error message, see “Interpreting

Error Codes” on page 119.

Step 1. Preset the instrument and select the digital modulation personality:

Press Press

Preset, Factory Preset (if available). MODE, Digital Modulation.

Step 2. Select the cdma2000 radio standard pre-set and base station device:

Press Press

Mode Setup, Radio, Radio Standard, cdma2000. Device (BTS), to underline BTS.

Step 3. Enable the modulation analysis mode to measure and display EVM and

other modulation metrics.

Press

MEASURE, Modulation Analysis.

Figure 2-44 I/Q Measured Polar Vector Graph (Default View)

Making Measurements

The measurement values for EVM, magnitude error, phase error, frequency error, I/Q offset and rho are shown in the summary window on the left side of the display.

Chapter 2 85

Making Measurements

Measuring Digital Modulation Formats

Step 4. View the I/Q error quad-view display to view the magnitude and phase

error components versus time and EVM versus time to quickly pin-point possible modulation problems:

Press

Trace/View, I/Q Error (Quad-View).

Figure 2-45 I/Q Error (Quad-View)

Step 5. View the eye quad-view display to quickly determine if the eye I and

eye Q diagrams are symmetrical with good symbol transitions.

Press

Trace/View, Eye (Quad-View).

Figure 2-46 Eye (Quad-View)

Making Measurements

86 Chapter 2

Making Measurements

Measuring Digital Modulation Formats

QAM Modulation Analysis (64QAM Example)

Supported QAM formats: 16QAM, 32QAM, 64QAM, 128QAM and 256QAM.

This section explains how to demodulate and analyze a 64QAM signal at 1 GHz, −10 dBm with a root nyquist filter alpha of 0.25 and a symbol rate of 5 Msps. This measurement procedure guides you through the different measurement views useful for modulation analysis.

Measurement Procedure

If you have a problem, and get an error message, see “Interpreting

Error Codes” on page 119.

Step 1. Preset the instrument and select the digital modulation personality:

Press Press Press

Preset, Factory Preset (if available). MODE, Digital Modulation. MEASURE, Modulation Analysis.

Step 2. Modify the demodulation parameters:

Press Press Press Press Press Press

Meas Setup, Demod. Modulation Format, More, 64QAM. Meas Filter, Root Nyquist. Ref Filter, Nyquist. Alpha/BT, 0.25, Enter. Symbol Rate, 5, MHz.

Figure 2-47 I/Q Measured Polar Vector Graph (Default View)

The measurement values for EVM, magnitude error, phase error, frequency error, I/Q offset and rho are shown in the summary window on the left side of the display.

Chapter 2 87

Making Measurements

Measuring Digital Modulation Formats

Step 3. View the I/Q error quad-view display to view the magnitude and phase

error components versus time and EVM versus time to quickly pin-point possible modulation problems:

Press

Trace/View, I/Q Error (Quad-View).

Figure 2-48 I/Q Error (Quad-View)

Step 4. View the eye quad-view display to quickly determine if the eye I and

eye Q diagrams are symmetrical with good symbol transitions.

Press

Trace/View, Eye (Quad-View).

Figure 2-49 Eye (Quad-View)

Making Measurements

88 Chapter 2

Making Measurements

Measuring Digital Modulation Formats

EDGE Modulation Analysis

This section explains how to demodulate and analyze an EDGE signal at 1 GHz, −10 dBm. This measurement procedure guides you through the different measurement views useful for modulation analysis.

Configuring the Measurement System

Refer to “Configuring a BTS Measurement System” on page 29 to connect the measurement equipment.

Measurement Procedure

If you have a problem, and get an error message, see “Interpreting

Error Codes” on page 119.

Step 1. Preset the instrument and select the digital modulation personality:

Press Press

Preset, Factory Preset (if available). MODE, Digital Modulation.

Step 2. Select the EDGE radio standard pre-set and base station device:

Press Press

Mode Setup, Radio, Radio Standard, EDGE. Device (BTS), to underline BTS.

Step 3. Enable the modulation analysis mode to measure and display EVM and

other modulation metrics.

Press

MEASURE, Modulation Analysis.

Figure 2-50 I/Q Measured Polar Vector Graph (Default View)

The measurement values for EVM, magnitude error, phase error, frequency error, I/Q offset and rho are shown in the summary window on the left side of the display.

Chapter 2 89

Making Measurements

Measuring Digital Modulation Formats

Step 4. View the I/Q error quad-view display to view the magnitude and phase

error components versus time and EVM versus time to quickly pin-point possible modulation problems:

Press

Trace/View, I/Q Error (Quad-View).

Figure 2-51 I/Q Error (Quad-View)

Step 5. View the eye quad-view display to quickly determine if the eye I and

eye Q diagrams are symmetrical with good symbol transitions.

Press

Trace/View, Eye (Quad-View).

Figure 2-52 Eye (Quad-View)

Making Measurements

90 Chapter 2

Making Measurements

Measuring Digital Modulation Formats

FSK Modulation Analysis (Bluetooth 2FSK Example)

Supported FSK formats: 2FSK, 4FSK and 8FSK.

This section explains how to demodulate and analyze a bursted Bluetooth signal at 1 GHz, −10 dBm. This measurement procedure guides you through the different measurement views useful for modulation analysis.

Measurement Procedure

If you have a problem, and get an error message, see “Interpreting

Error Codes” on page 119.

Step 1. Preset the instrument and select the digital modulation personality:

Press Press

Preset, Factory Preset (if available). MODE, Digital Modulation.

Step 2. Select the Bluetooth radio standard pre-set:

Press

Mode Setup, Radio, Radio Standard, More, Bluetooth.

Step 3. Enable the modulation analysis mode to measure and display EVM and

other modulation metrics.

Press

MEASURE, Modulation Analysis.

Step 4. Set the trigger source to capture the Bluetooth burst:

Press Press

Meas Setup, Trig Source, RF Burst (Wideband). Meas Control, Restart.

Figure 2-53 I/Q Measured Polar Vector Graph (Default View)

In Figure 2-53, the measurement values for FSK error, magnitude error, carrier offset and deviation are shown in the summary window on the left side of the display.

Chapter 2 91

Making Measurements

Measuring Digital Modulation Formats

Step 5. View the FSK error quad-view display:

Press

Trace/View, FSK Error (Quad-View).

The FSK error quad-view display contains FSK error versus time, FSK error spectrum, FSK measured time and a numeric summary table. You can zoom in on any of these views for better resolution.

Figure 2-54 FSK Error (Quad-View)

Step 6. View the numeric results table to quickly determine where problems

might exist in the modulation.

Press

Trace/View, Numeric Results.

Figure 2-55 FSK Numeric Results

Making Measurements

92 Chapter 2

Making Measurements

Measuring Digital Modulation Formats

MSK Modulation Analysis (GSM MSK type 1 Example)

Supported MSK formats: MSK type 1 and MSK type 2.

This section explains how to demodulate and analyze a GSM signal at 1 GHz and −10 dBm. This measurement procedure guides you through the different measurement views useful for modulation analysis.

Configuring the Measurement System

Refer to “Configuring a BTS Measurement System” on page 29 to connect the measurement equipment.

Measurement Procedure

If you have a problem, and get an error message, see “Interpreting

Error Codes” on page 119.

Step 1. Preset the instrument and select the digital modulation personality:

Press Press

Preset, Factory Preset (if available). MODE, Digital Modulation.

Step 2. Select the GSM radio standard pre-set and base station device:

Press Press

Mode Setup, Radio, Radio Standard, GSM. Device (BTS), to underline BTS.

Step 3. Enable the modulation analysis mode to measure and display EVM and

other modulation metrics.

Press

MEASURE, Modulation Analysis.

Figure 2-56 I/Q Measured Polar Vector Graph (Default View)

The measurement values for EVM, magnitude error, phase error, frequency error and I/Q offset are shown in the summary window on the left side of the display.

Chapter 2 93

Making Measurements

Measuring Digital Modulation Formats

Step 4. View the I/Q error quad-view display to view the magnitude and phase

error components versus time and EVM versus time to quickly pin-point possible modulation problems:

Press

Trace/View, I/Q Error (Quad-View).

Figure 2-57 I/Q Error (Quad-View)

Step 5. View the eye quad-view display to quickly determine if the eye I and

eye Q diagrams are symmetrical with good symbol transitions.

Press

Trace/View, Eye (Quad-View).

Figure 2-58 Eye (Quad-View)

Making Measurements

94 Chapter 2

Making Measurements

Analyzing and Troubleshooting Digital Signals

EVM Troubleshooting Procedure Overview

Measurements of EVM and related quantities can pin-point the causes of many problems uncovered during the design stages. This section provides general guidance for troubleshooting those problems and the techniques to determine what kind of impairments could be due to your design or testing procedure. Figure 2-59 shows the troubleshooting procedure to help determine the root cause of your measurement results.

If you have high EVM results, the first step is to break the EVM result into phase and magnitude components. With phase and magnitude errors, you can determine whether you need to view phase error vs. time, magnitude error vs. time or the I/Q constellation. For example, if you determined the phase error and magnitude error add about the same amount of error to the EVM result and the I/Q constellation is symmetric then you should look closely at EVM vs. time.

Figure 2-59 Flow Chart for EVM Troubleshooting

Making Measurements

Chapter 2 95

Making Measurements

Analyzing and Troubleshooting Digital Signals

Measurement 1 - Obtaining EVM Results with Phase Error and Magnitude Error

The PSA Option 241 can help design engineers pin-point signal errors or measurement set-up errors from basic digitally modulated signals to complex digitally modulated high data rate signals.

To demonstrate using PSA option 241 for troubleshooting signal and set-up impairments, a W-CDMA signal is used.

Step 1. Generate a downlink (base station) W-CDMA signal with 1 data

channel (DPCH). Set the carrier frequency at 1 GHz with an amplitude of −10 dBm. The W-CDMA signal is impairment free.

Step 2. Setup the PSA to demodulate the W-CDMA signal using option 241:

Press Press Press Press

Preset, Factory Preset (if available). MODE, Digital Modulation. FREQUENCY Channel, Center Freq, 1, GHz. MEASURE, Modulation Analysis.

Step 3. View the numeric results and note the average (RMS) EVM, RMS

magnitude error and RMS phase error results:

Press

Trace/View, Numeric Results.

If you have higher than expected RMS and/or peak EVM results, look at the RMS magnitude error (number 1 in Figure 2-60) and RMS phase error (number 2 in Figure 2-60). If the phase error is relatively larger (greater than 3-4 times) than the magnitude error go to “Measurement

2 - Phase Error vs. Time” on page 97. If the magnitude error is

relatively larger (greater than 3-4 times) than the phase error go to

“Measurement 3 - Magnitude Error vs. Time” on page 98. If the phase

error and magnitude error are approximately the same go to

“Measurement 4 - I/Q Constellation Diagram” on page 99.

Figure 2-60 Numeric Results (comparing phase and magnitude errors)

not

similar

Making Measurements

96 Chapter 2

Analyzing and Troubleshooting Digital Signals

Measurement 2 - Phase Error vs. Time

Measurement procedure: use if phase error >> magnitude error.

Description: Phase error is the instantaneous angle difference between the measured signal and the ideal reference signal. When viewed as a function of time (or symbol), it shows the modulating waveform of any residual or interfering PM signal.

Step 1. Display the phase error versus time (symbols) results:

Making Measurements

Press Press

Trace/View, I/Q Error (Quad-View). Next Window, Zoom.

The full screen view should now be the phase error diagram.

Step 2. Adjust the vertical scale as necessary to view the phase error:

Press

By manually changing the are not sure what

AMPLITUDE Y Scale, Scale/Div then adjust as necessary.

Scale/Div, the Scale Coupling turns off. If you

Scale/Div to use, set Scale Coupling to on.

Step 3. For more detail, expand the waveform by reducing the result length or

by reducing the x-scale per division.

Press Press

Meas Setup, Demod, Meas Interval, or SPAN X Scale, Scale/Div, then adjust the measurement interval or

x-axis as necessary.

TIP The x-axis scale is in symbols. To calculate absolute time, divide the

number of symbols by the symbol rate.

Observe: Sine waves or other regular waveforms indicate an interfering signal. See “In-Channel Phase Modulating (PM) Interference” on

page 107 for an example of residual PM. Uniform noise is a sign of some

form of phase noise (i.e. random jitter). See Figure 2-61 for an example.

Figure 2-61 Phase Error Zoom View - Example of Uniform Noise

Chapter 2 97

Making Measurements

Analyzing and Troubleshooting Digital Signals

Measurement 3 - Magnitude Error vs. Time

Measurement procedure: use if phase error << magnitude error.

Description: Magnitude error is the instantaneous amplitude difference between the measured signal and the ideal reference signal. When viewed as a function of time (or symbol), it shows the modulating waveform of any residual or interfering AM signal.

Step 1. Display the magnitude error versus time (symbols) results:

Press

Trace/View, I/Q Error (Quad-View). (Confirm the current selected

view is Mag Error. The current selection is outlined in green.) Press

NOTE If you need to go back to the quad-view, press Zoom one more time.

Zoom.

The full screen view should now be the magnitude error diagram.

Step 2. Adjust the vertical scale as necessary to view the magnitude error:

Press

By manually changing the are not sure what

AMPLITUDE Y Scale, Scale/Div then adjust as necessary.

Scale/Div, the Scale Coupling turns off. If you

Scale/Div to use, set Scale Coupling to on.

Step 3. For more detail, expand the waveform by reducing the result length or

by reducing the x-scale per division.

Press Press

Meas Setup, Demod, Meas Interval, or SPAN X Scale, Scale/Div, then adjust the measurement interval or

x-axis as necessary.

If magnitude error versus time shows a curve response then amplitude droop could be the problem. If you see a waveform pattern then residual AM could be the problem. See “In-Channel Amplitude Modulation (AM)

Interference” on page 109 for an example of residual AM.

Making Measurements

Figure 2-62 Magnitude Error Zoom View - Example of Uniform Noise

98 Chapter 2

Making Measurements

Analyzing and Troubleshooting Digital Signals

Measurement 4 - I/Q Constellation Diagram

Measurement procedure: use if phase error ≅ magnitude error.

Description: This is a common graphical analysis technique utilizing a polar plot to display a vector-modulated signal’s magnitude and phase relative to the carrier, as a function of time or symbol. The phasor values at the symbol clock times are particularly important, and are highlighted with a dot (at a symbol point). In order to accomplish this, a constellation analyzer must know the precise carrier and symbol clock frequencies and phases, either through an external input or through automatic locking, as with PSA Option 241.

Step 1. Display the I/Q measured time polar constellation graph (default view):

Press

Trace/View, I/Q Measured Polar Graph.

The individual constellation “dots” represent the modulation symbol states. The lines connecting the states are the signal “trajectories” for the phase and amplitude of the modulation between symbols.

Step 2. Adjust the number of I/Q points displayed in the constellation view:

Press

Display, I/Q Points.

For a constellation with a low number of symbol states, enter a number at least several times the number of states in the constellation. That will allow each state to clearly show the distribution of measured symbols. If no symbol “dot” is shown, it may mean that state was not transmitted. You may need to use random data to see all the “dots”.

TIP I/Q Points determines how many dots will appear on the constellation.

Increase it to populate the constellation states more completely.

I/Q Points cannot exceed the measurement interval.

If you are examining a constellation that contains a large number of symbol states, like 256QAM, it may become difficult to see individual trajectories. It can be helpful to limit the number of “dots” shown by adjusting the number of symbols displayed lower than the number of symbol states in the constellation, and repeating the measurement to “see” all the constellation dots and the trajectories.

Step 3. Adjust the number of points/symbol displayed in the constellation view:

Press

TIP Points/symbol determines how much detail is shown between symbols.

Display, Points/Symbol.

To see peaks and overshoot due to filter errors, use four or more points/symbol.

To allow a longer result length, use fewer points (in either case, result length multiplied by points/symbol must be less than max time points).

Chapter 2 99

Making Measurements

Analyzing and Troubleshooting Digital Signals

One point per symbol creates misleading eye and constellation diagrams, because no intersymbol data is collected and all symbols are connected by straight, direct lines.

Step 4. Check the I/Q constellation for symmetry.

Observe: A perfect signal will have a uniform constellation that is perfectly symmetric about the origin. Asymmetrical constellations fall into the following categories:

• I/Q imbalance (“I/Q Gain Imbalance” on page 103) is indicated when the constellation is not “square,” that is when the Q-axis height does not equal the I-axis width.

• Quadrature error (“I/Q Quadrature Skew” on page 105) is seen as a “tilt” to the constellation.

• I/Q offset (“I/Q DC Offset Error” on page 106) shows up as a numeric result, since the PSA only reports the value and adjusts the constellation to remove any offset.

Step 5. In some cases it may be easier to spot modulation problems if the

symbol trajectories are turned off:

Press

Display, I/Q Polar Type, Constellation.

Typical problems that can be easily identified by viewing the constellation points are compression and interfering spurious signals. Compression is the result of higher phase errors at larger signal amplitudes.

• Interfering spur - “In-Channel Spurious Signal Interference” on

page 111 shows up as rings at the symbol points.

• Compression - symbol point shadowing effect

Step 6. If the constellation is symmetric with no abnormalities, continue to

measurement 5, to analyze EVM versus time.

Figure 2-63 I/Q Measured Polar Vector (Left) and Constellation (Right)

Making Measurements

100 Chapter 2

Agilent E4445A Flexible Digital Modulation Analysis Guide

Specifications and Main Features

Frequently Asked Questions

User Manual

Table of Contents

List of Commands

1 Introduction

What Does the Agilent PSA Option 241 Do?

Installing Optional Measurement Personalities

Do You Have Enough Memory to Load All Your Personality Options?

How to Predict Your Memory Requirements

Loading an Optional Measurement Personality

Obtaining and Installing a License Key

Viewing a License Key

Using the Delete License Key on PSA

Ordering Optional Measurement Personalities

2 Making Measurements

Introduction

Setting Up the Test Equipment and DUT

Making the Initial Signal Connection

Configuring a MS Measurement System

Configuring a BTS Measurement System

Using Instrument Presets

Determining the RF Parameters of Your Signal

Using the Spectrum Measurement to View the RF Parameters of the Signal Under Test

Spectrum (Frequency Domain) Measurements

Using the Waveform Measurement to Set Up Triggering (for burst signals)

Waveform (Time Domain) Measurements

Modulation Analysis Measurements in 8 Steps

Modulation Analysis Measurement Final Checks

Modifying Measurement Setup Parameters

Using the Measurement Setup Form

Setting Demodulation Parameters

Setting up a Trigger Source

Setting Burst/Sync Properties

Using Adaptive Equalization

Setting Advanced Measurement Setup Properties

Measuring Digital Modulation Formats

Setting up the Modulation Analysis Personality

Viewing the I/Q Polar Vector and Constellation Graphs

Viewing the Numeric Measurement Results

Viewing the I/Q Error (Quad-View) Results

Viewing the Magnitude Error Versus Time Results

Viewing the Phase Error Versus Time Results

Viewing the EVM Versus Time Results

Viewing the Eye Diagram Results

Viewing the FSK Error (Quad-View) Results

Viewing the FSK Error Versus Time Results

Viewing the FSK Error Spectrum Results

Viewing the FSK Measured Time Results

PSK Modulation Analysis (cdma2000 QPSK Example)

QAM Modulation Analysis (64QAM Example)

EDGE Modulation Analysis

FSK Modulation Analysis (Bluetooth 2FSK Example)

MSK Modulation Analysis (GSM MSK type 1 Example)

Analyzing and Troubleshooting Digital Signals

EVM Troubleshooting Procedure Overview

Measurement 1 - Obtaining EVM Results with Phase Error and Magnitude Error

Measurement 2 - Phase Error vs. Time

Measurement 3 - Magnitude Error vs. Time

Measurement 4 - I/Q Constellation Diagram