Tektronix RSA6106A, RSA6114A, RSA6120A Online Help

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RSA6100A Series

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Real-Time Spectrum Analyzers

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RSA6100A Series Real-Time Spectrum Analyzers

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Copyright © Tektronix. All rights reserved. Licensed software products are owned by Tektronix or its subsidiaries or suppliers, and are protected by national copyright laws and international treaty provisions.

Tektronix products are covered by U.S. and foreign patents, issued and pending. Information in this publication supersedes that in all previously published material. Speciﬁcations and price change privileges reserved.

TEKTRONIX and TEK are registered trademarks of Tektronix, Inc.

Microsoft, Windows, and Windows XP are registered trademarks of Microsoft Corporation.

Compiled Online Help p art number: 076-0070-06

Version 2.3.00159, May 12, 2010

Contacting Tektronix

Tektronix, Inc. 14200 SW Karl Braun Drive P. O . B o Beaverton, OR 97077 USA

For product information, sales, service, and technical support:

x500

In North America, call 1-800-833-9200.

dwide, visit w

Worl

ww.tektronix.com to ﬁnd contacts in your area.

Table of Contents

Welcome

Welcome............................................................................................................. 1

About Tektronix Spectrum Analyzers

Your Tektronix Spectrum Analyzer............................................................................... 2

Product Software .... ................................ ................................ ............................... 3

Accessories

Standard Accessories.......................................................................................... 4

Recommended Accessories................................................................................... 5

Options

Options.......................................................................................................... 6

Documentation and Support

Documentation ................................................................................................. 7

Table of Contents

Orientation

Front Panel Connectors ..... .................................. ................................ ..................... 8

Front-Panel Controls .................................... .................................. ......................... 8

Touch Screen............................. ................................ ................................ .......... 11

Touch-Screen Actions............................................................................................. 11

Elements of the Display........................................................................................... 14

Rear-Panel Connectors.............. ................................ ................................ .............. 18

Setting Up Network Connections . .... . .... .... . .... . .... . .... ..... .... . .... . .... ... . . .... . .... . .... ..... .... . ... 18

Operating Your Instrument

Restoring Default Settings.............. ................................ .................................. ........ 19

Running Alignments .............................. ................................ ................................ 19

Application Presets ................ .................................. ................................ .............. 20

Setting Options. ... . . .... . .... . .... . .... .... . .... . .... . .... . .... .... . .... . .... . .... . .... .... . .... . .... . .... . .... .... 24

Using the Measurement Displays

Selecting Displays ................................. ................................ ................................ 26

Taking Measurements

Measurements

Available Measurements. ................................ .................................. .................. 27

General Signal Viewing

Overview ........................................................................................................... 33

RSA6100A Series Real-Time Spectrum Analyzers Help i

Table of Contents

DPX Spectrum

DPX Primer ............................. .................................. ................................ .... 34

DPX Spectrum Overview .................................................................................... 57

DPX Spectrum Display ...... ................................ .................................. .............. 57

DPX Spectrum Settings .. . ... . . .... . .... . .... . .... . .... . .... . .... . .... . .... . .... . .... ..... ..... ..... ..... .... 61

Time Overview

Time Overview Display...................................................................................... 72

Time Overview Settings ..................................................................................... 74

Spectrum

Spectrum Display............. .................................. ................................ .............. 78

Spectrum Settings.. ... . . .... . .... .... . .... . .... .... . .... . .... ... . . .... . .... .... . .... . .... ... . . .... . .... .... . .. 80

Spectrogram

Spectrogram Display ................... ................................ ................................ ...... 82

Spectrogram Settings . .... . .... . .... ... . . .... . .... . .... ... . . .... . .... ..... .... . .... . .... ... . . .... . .... ..... ... 85

Amplitude Vs Time

Amplitude Vs Time Display... ................................ .................................. ............ 89

Amplitude Vs Time Settings ................................ ................................ ................ 90

Frequency Vs Time

Frequency Vs Time Display ................................................................................. 92

Frequency Vs Time Settings.. ..... .... . .... . .... . .... . .... . .... . .... ..... ..... .... . .... . .... . .... . .... ..... . 93

Phase Vs Time

Phase Vs Time Display....................................................................................... 94

Phase Vs Time Settings . .... . .... ... . . .... . .... . .... . .... . .... . .... .... . .... . .... . .... . .... . .... . .... ... . . ... 95

RF I & Q Vs Time

RF I & Q vs Time Display................................................................................... 96

RF I & Q vs Time Settings. . .... . .... . .... ..... ... . . .... . .... . .... . .... . .... . .... ..... ..... .... . .... . .... . ... 97

Common Controls for General Signal Viewing Displays

General Signal Viewing Shared Measurement Settings . ..... .... . .... . .... ..... ..... .... . .... . .... ..... . 98

Analog Modulation

Overview ......................................................................................................... 108

AM Display ..... ................................ .................................. .......................... 109

AM Settings ................................................................................................. 110

FM Display.................................................................................................. 116

FM Settings.. . .... ..... .... . .... . .... ..... ... . . .... . .... . .... .... . .... . .... . .... . .... .... . .... . .... . .... ..... 118

PM Display.................................................................................................. 124

PM Settings.. . .... ..... .... . .... . .... ..... ... . . .... . .... . .... .... . .... . .... . .... . .... .... . .... . .... . .... ..... 126

ii RSA6100A Series Real-Time Spectrum Analyzers Help

RF Measurements

Overview ......................................................................................................... 132

Channel Power and ACPR

Channel Power and ACPR (Adjacent Channel Power Ratio) Displ

Channel Power and ACPR Settings .................... ................................ .................. 136

MCPR

MCPR (Multiple Carrier Power Ratio) Display . .... . .... . .... .... . .... . .... ... . . .... . .... ... . . .... . .... 139

MCPR Settings........ .................................. ................................ .................... 142

Occupied BW & x dB BW

Occupied BW & x dB BW Display......................... ................................ .............. 149

Occupied BW & x dB BW Settings ...... ................................ ................................ 151

Spurious

Spurious Display............................................................................................ 153

Spurious Display Settings. .... . .... . .... . .... ..... ..... .... . .... . .... . .... . .... ..... ..... .... . .... . .... . ... 157

CCDF

CCDF Display............................................................................................... 167

CCDF Settings . . .... .... . .... . .... .... . .... . .... .... . .... . .... ... . . .... . .... ... . . .... . .... ... . . .... . .... .... 168

Phase Noise

Phase Noise Display........................................................................................ 170

Phase Noise Settings . . .... . .... ..... ... . . .... . .... . .... . .... . .... ..... ..... .... . .... . .... . .... . .... . .... . .. 174

Settling Time Measurements

Settling Time Measurement Overview ... . .... . .... .... . .... . .... ..... ... . . .... . .... . .... .... . .... . .... .. 177

Settling Time Displays

Settling Time Displays ... . . .... . .... . .... ... . . .... . .... . .... . .... .... . .... . .... . .... . .... .... . .... . .... . ... 182

Settling Time Settings .. . .... . .... ..... ..... .... . .... . .... . .... . .... ..... ..... .... . .... . .... . .... . .... . .... . 189

Common Controls for Settling Time Displays

Settling Time Displays Shared Measurement Settings .... . .... ..... ..... .... . .... . .... ..... ..... .... . . 190

Common Controls for RF Measurements Displays

RF Measurements Shared Measurement Settings ... . . .... . .... . .... .... . .... . .... . .... ..... .... . .... . .. 198

Table of Contents

ay................................ 133

Pulsed RF

Overview ......................................................................................................... 205

Pulse Table Display

Pulse Table Display............................... ................................ .......................... 206

Pulse Table Settings . ... . . .... . .... ..... .... . .... . .... .... . .... . .... ... . . .... . .... ..... .... . .... . .... ... . . .. 207

Pulse Trace Display

Pulse Trace Display......... ................................ ................................ ................ 208

Pulse Trace Settings . . .... . .... . .... . .... . .... . .... . .... ..... ..... ... . . ... . . .... . .... . .... . .... . .... . .... . .. 209

Pulse Statistics

Pulse Statistics Display..................................................................................... 210

Pulse Statistics Settings .... . .... . .... . .... . .... ..... ..... .... . .... . .... . .... . .... .... . .... . .... . .... . .... .. 212

Common C ontrols for Pulsed RF Displays

RSA6100A Series Real-Time Spectrum Analyzers Help iii

Table of Contents

Pulsed RF Shared Measurement Settings .... . .... ..... .... . .... . .... . .... ..... .... . .... . .... . .... ..... .. 213

GP Digital Modulation

Overview ......................................................................................................... 224

Constellation

Constellation Display....................................................................................... 226

Constellation Settings . . .... ..... .... . .... . .... . .... .... . .... . .... ... . . .... . .... ..... ... . . .... . .... ..... .... 227

Demod I & Q vs Time

Demod I & Q vs Time Display............................................................................ 228

Demod I & Q vs Time Settings .... . .... .... . .... . .... . .... . .... .... . .... . .... . .... . .... .... . .... . .... . ... 230

EVM vs Time

EVM vs Time Display............................................ ................................ .......... 231

EVM vs Time Settings ..... .... . .... . .... . .... . .... ..... ..... .... . .... . .... . .... . .... ..... ..... .... . .... . .. 232

Eye Diagram

Eye Diagram Display............................. ................................ .......................... 233

Eye Diagram Settings .......... ................................ .................................. .......... 235

Frequency Deviation vs Time

Frequency Deviation vs Time Display ................................................................... 236

Frequency Deviation vs Time Settings ... . .... . .... . .... . .... ..... ..... .... . .... . .... . .... . .... .... . .... . 238

Magnitude Error vs Time

Magnitude Error vs Time Display .............. .................................. ........................ 239

Magnitude Error vs Time Settings .................. .................................. .................... 241

Phase Error vs Time

Phase Error vs Time Display .... ................................ .................................. ........ 242

Phase Error vs. Time Settings . .... ..... ..... ... . . ... . . .... . .... . .... . .... . .... . .... . .... . .... . .... . .... . .. 244

Signal Quality

Signal Quality Display .... . .... .... . .... . .... ..... ... . . .... . .... . .... .... . .... . .... ..... ... . . .... . .... . .... 245

Signal Quality Settings.. . . .... . .... . .... . .... .... . .... . .... . .... . .... .... . .... . .... . .... . .... .... . .... . .... 250

Symbol Table

Symbol Table Display.......................... .................................. .......................... 251

Symbol Table Settings.... . .... . .... . .... . .... ..... ..... .... . .... . .... . .... . .... . .... . .... ..... ..... ... . . ... 252

Trellis Diagram

Trellis Diagram Display.. . .... . .... ..... ..... .... . .... . .... . .... ..... .... . .... . .... . .... . .... .... . .... . .... 253

Trellis Diagram Settings . .... .... . .... . .... . .... . .... .... . .... . .... . .... . .... .... . .... . .... . .... . .... .... . . 255

Common Controls for GP Digital Modulation Displays

GP Digital Modulation Shared Measurement Settings ................................................. 256

Standard Settings Button .... . .... . .... ... . . .... . .... ..... .... . .... . .... .... . .... . .... ... . . .... . .... ..... ... 257

Symbol Maps

Symbol Maps.................................. ................................ .............................. 271

User Filters

Overview: User Deﬁned Measurement and Reference Filters... .... . .... . .... ..... ... . . .... . .... . .... 277

User Filter File Format . . .... . .... . .... ..... .... . .... . .... . .... ..... .... . .... . .... . .... ..... .... . .... . .... . . 277

iv RSA6100A Series Real-Time Spectrum Analyzers Help

Marker Measurements

Using Markers

Using Markers............................................................................................... 281

Controlling Markers with the Touchscreen Actions Menu . ..... ... . . .... . .... . .... ..... ..... .... . .... . 282

Measuring Signal Density, Frequency and Power on a DPX Bitmap Trace.......................... 282

Measuring Frequency and Power in the Spectrum Display.... .................................. ...... 284

Common Marker Actions

Marker Action Controls............................................................................... 285

Peak.. ................................ .................................. ................................ .. 285

Next Peak ............................................................................................... 285

Marker to Center Frequency.......................................................................... 285

Deﬁne Markers Control Panel

Enabling Markers and Setting Marker Properties . .... . .... . .... . .... ... . . .... . .... . .... . .... ... . . . 286

Markers Toolbar

Using the Markers Toolbar.. ................................ ................................ .......... 288

Noise Markers in the Spectrum Display

Using Noise Markers in the Spectrum Display........... .................................. ........ 289

Table of Contents

Search (Limits Testing)

The Search Tool (Limits Testing).. .................................. ................................ .......... 291

Search (Limits Testing) Settings ............................................................................... 291

Deﬁne Tab (Search) ................. ................................ ................................ ............ 291

Actions Tab....................... ................................ ................................ ................ 296

Analyzing Data

Analysis Settings

Analysis Settings............................ .................................. .............................. 297

Analysis Time Tab.......................................................................................... 297

Spectrum Time Tab....................... ................................ ................................ .. 299

Frequency Tab............................................................................................... 299

Units Tab............................. ................................ ................................ ........ 302

Analyzing Data Using Replay

Replay Overview ........................................................................................... 303

Replay Menu ...... ................................ ................................ .......................... 305

Play All Selected Records ................................................................................. 305

Play Current ................... ................................ ................................ .............. 305

Play from Selected........................................................................................... 306

Pause ............................. .................................. ................................ .......... 306

Stop........................................................................................................... 306

Select All .................................................................................................... 306

Select Records from History............................................................................... 306

Replay Toolbar .............................................................................................. 306

RSA6100A Series Real-Time Spectrum Analyzers Help v

Table of Contents

Amplitude Corrections

Amplitude Settings . .... . .... .... . .... . .... . .... . .... .... . .... . .... . .... . .... .... . .... . .... . .... . .... .... . .... . .. 308

Internal Settings Tab . . .... ..... ..... .... . .... . .... . .... . .... . .... . .... ..... ..... .... . .... . .... . .... . .... ..... ... 308

External Gain/Loss Correction Tab.................................. .................................. ........ 311

External Gain Value ........................................................................................ 312

Apply Table Corrections To ............................................................................... 312

External Loss Tables ....................................................................................... 313

External Probe Correction Tab ................................................................................. 315

Controlling the Acquisition of Data

Acquisition Controls in the Run Menu

Continuous Versus Single Sequence............ ................................ .......................... 316

Run ................................. ................................ .................................. ........ 316

Resume....................................................................................................... 316

Abort ............................. .................................. ................................ .......... 316

UsingTriggerstoCaptureJustWhatYouWant

Triggering

Triggering............................................................................................... 317

Frequency Mask Trigger .............................................................................. 320

Mask Editor (Frequency Mask Trigger)........................... ................................ .. 320

Trigger Settings .... .... . .... . .... .... . .... . .... ... . . .... . .... ... . . .... . .... ... . . .... . .... ... . . .... . .... 324

Event Tab ............................................................................................... 324

Time Qualiﬁed Tab .................................................................................... 331

Advanced Tab (Triggering) . ................................ .................................. ........ 332

Actions Tab (Triggering) .............................................................................. 333

Managing Data, Settings, and Pictures

Saving and Recalling Data, Settings, and Pictures... ..... ..... .... . .... . .... . .... . .... . .... . .... ..... ..... .. 334

Data, Settings, and Picture File Formats ... . .... .... . .... . .... .... . .... . .... ..... .... . .... . .... ..... .... . .... . 336

Printing Screen Shots ........................................................................................... 340

Reference

Online Help ...................................................................................................... 341

About the RSA6100A Series................................................................................... 342

Connecting Signals

Conﬁgure In/Out Settings .... . .... . .... .... . .... . .... .... . .... . .... .... . .... . .... .... . .... . .... .... . .... . .. 343

Connecting an RF Signal .................................................................................. 344

Connecting a Signal Using a TekConnect Probe.. ................................ ...................... 345

Connecting External Trigger Signals..................................................................... 345

al I/Q Output ........ .................................. ................................ ................ 346

Digit

IQ Outputs ......................... ................................ .................................. ........ 346

Analog IF Output ........................................................................................... 346

vi RSA6100A Series Real-Time Spectrum Analyzers Help

Table of Contents

Other Outputs ............................................................................................... 347

Menus

Menu Overview

File Menu

File Menu ............................................................................................... 349

Application Presets... ........ .................................. ................................ ........ 353

View Menu

View Menu ............................................................................................. 354

Run Menu

Run Menu................................... ................................ ............................ 356

Replay

Replay Menu ........................................................................................... 358

Markers Menu

Markers Menu .......................................................................................... 359

Setup M

Tools Me nu

Window Menu

Help

Troubleshooting

Error and Information Messages .......................................................................... 366

Displaying the Windows Event Viewer .................................................................. 374

On/Standby Switch

Upgrading the Instrument Software

How to Find Out If Instrument Software Upgrades Are Available.................................... 378

Changing Settings

Settings. .... . .... . .... . .... . .... . ..... .... . ..... ... . . ..... ..... ..... ..... ..... ..... ..... ..... . .... ..... . .... .. 379

enu

Setup Menu........... ................................ .................................. ................ 360

Tools Menu ..................... ................................ .................................. ...... 361

Arranging Displays .................................................................................... 364

Help Menu.................. .................................. ................................ .......... 365

n/Standby Switch ................................... .................................. .................... 377

............................................................................................. 348

Glossary

Index

RSA6100A Series Real-Time Spectrum Analyzers Help vii

Table of Contents

viii RSA6100A Series Real-Time Spectrum Analyzers Help

Welc ome Welc ome

Welcome

This help provides in-depth information on how to use the RSA6100A Series Real-Time Spectrum Analyzers. This online help contains the most complete descriptions of how to use the spectrum analyzer. For a shorter introduction to the spectrum analyzer, refer to the RSA6100A Series Real Time Spectrum Analyzer Quick Start User Manual.

RSA6100A Series Real-Time Spectrum Analyzers Help 1

About Tektronix Spectrum Analyzers Your Tektronix Spectrum Analyzer

Your Tektronix Spectrum Analyzer

The RSA6100A Series will help you to easily discover design issues that other signal analyzers may miss. The revolutionary DPX spectrum display offers an intuitive live color view of signal transients changing over time in the frequency domain, giving you immediate conﬁdence in the stability of your design, or instantly displaying a fault when it occurs. This live display of transients is impossible with other signal analyzers. Once a problem is discovered with DPX, the RSA6100A Series of Real-Time Spectrum Analyzers (RTSA) can be set to trigger on the event, capture a continuous time record of changing RF events and perform time-correlated analysis in all domains. You get the functionality of a wideband vector signal analyzer, a spectrum analyzer and the unique trigger-capture-analyze capability of a Real-Time Spectrum Analyzer — all in a single package.

Discover

DPX Minimum Event Time Capture: 24 μs (option 110), 31 μs (standard); 10.3 μs (option 110 + option 200), 24 μs (option 200).

Trigger

Tektronix exclusive 40 MHz and 110 MHz DPX Density and Frequency Mask triggers offer easy event-based capture of transient RF signals by triggering on any change in the frequency domain.

Capture

All signals within a 110 MHz bandwidth span arecapturedintomemory(Option110only,40MHz acquisition bandwidth standard).

Up to 1.7 seconds acquisition length at 110 MHz bandwidth provides complete analysis over time without making multiple acquisitions.

Analyze

Extensive time-correlated multi-domain displays connect problems in time, frequency, phase a nd amplitude for quicker understanding of cause and effect when troubleshooting.

Power measurements and signal statistics help you charac terize components and systems: ACLR, Multi-Carrier ACLR, Power vs. Time, CCDF, Phase Noise, and Spurious.

Advanced Measurement Suite (Opt. 20): Pulse measurements including rise time, pulse width, duty, ripple, power, frequency and phase provide deep insight into pulse train behavior.

General Purpose Digital Modulation Analysis (Opt. 21): Provides vector s ignal analyzer functionality.

2 RSA6100A Series R eal-Time Spectrum Analyzers Help

About Tektronix Spectrum Analyzers Product Software

Product Softw

The instrumen

System Software: The product software runs on a s pecially conﬁgured version of Windows XP. As with stand you need to reinstall the operating system, follow the procedure in the Restoring the Operating System chapter in the RSA6100A Series Real-Time Spectrum Analyzers Service manual (Tektronix part number 077-0250-XX). You can download a PDF version of the Service manual at w

ww.tektronix.com/manuals. Do not substitute any version of Windows that is not speciﬁcally

provided by Tektronix for use with your instrument.

Product Software: The product software is the instrument application. It provides the user interface (UI) and all other instrument control functions. You can minimize or even exit/restart the instrument applica

Occasionally new versions of software for your instrument may become available at our Web site. Visit

ww.te

Software and Hardware Upgrades

Tektronix may offer software or hardware upgrade kits for this instrument. Contact your local Tektronix distributor or sales o fﬁce for more information.

tion as your needs dictate.

ktronix.com/software for information.

are

t includes the following software:

ard Windows XP installations, you can install other compatible applications. If

RSA6100A Series Real-Time Spectrum Analyzers Help 3

About Tektronix Spectrum A nalyzers > Accessories Standard Accessories

Standard Accessories

The standard accessories for the RSA6100A Series instruments are shown below. For the latest information on available accessories, see the T

Quick Start User Manual

English - Option L0, Tektronix part number 071-1909-XX

Japanese - Option L5, Tektronix part number 071-1911-XX

Russian, Option L10, Tektronix part number 071-1912-XX

Simpliﬁed Chinese - Option L7, Tektronix part number 071-1910-XX

Applications Instructions

ektronix Web site .

Tektronix part number 071-2590-XX

Product Documentation CD-ROM

The Product Documentation CD-ROM contains PDF versions of all printed manuals. The Product Documentation CD-ROM also contains the following manuals, some of which are available only in PDF format:

Declassiﬁcation and Security Instructions manual PDF, Tektronix part number 077-0170-XX

Service Manual PDF, Tektronix part number 077-0250-XX

Programmer Manual PDF, Tektronix part number 077-0249-XX

Speciﬁcations and Performance Veriﬁcation PDF, Tektronix part number 077-0251-XX

lease notes

Other related materials

OTE. To check for updates to the instrument documentation, browse to w

and search by your instrument’s model number.

ww.tektronix.com/manuals

4 RSA6100A Series R eal-Time Spectrum Analyzers Help

About Tektronix Spectrum Analyzers > Acce ssories Recommended Accessories

Important Docu

ments Folder

Certiﬁcate of Calibration documenting NIST traceability, 2540-1 compliance, and ISO9001 registration

Power Cords

North Ameri

Universal Euro - Option A1, Tektronix part number 161-0104-06

United Kingdom - Option A2, Tektronix part number 161-0104-07

Australia - Option A3, Tektronix part number 161-0104-05

240V North America - Option A4, Tektronix part number 161-0104-08

Switzerland - Option A5, Tektronix part number 161-0167-00

Japan - O

China - Option A10, Tektronix part number 161-0306-00

India - Option A11, Tektronix part number 161-0324-00

No power cord or AC adapter - Option A99

ca - Option A0, Tektronix part number 161-0104-00)

ption A6, Tektronix part number 161-A005-00

Optical Wheel Mouse

Product Software CD

Recommended A ccessories

The recommended accessories for the RSA6100A Series instruments are shown in the following table. For the latest information on available accessories, see the T

Item

Additional Removable Hard Drive for use with Option 06

Windows XP and instrument software installed)

(

ransit Case

Rackmount Installation Kit 016-1962-00

Additional Quick Start User Manual (paper)

Additional Documents CD (all manuals in PDF format)

xxx

ektronix Web site .

Ordering part number

RSA61RHD

016-1963-00

071-1909-XX

063-3930-XX

RSA6100A Series Real-Time Spectrum Analyzers Help 5

About Tektronix Spectrum Analyzers > Options Options

Options

To view a listing of the software options installed on your instrument, select Help > About Your Tektronix Real-Time Spectrum Analyzer. There is a label on the rear-panel of the instrument that

lists installed hardware options.

Options can be added to your instrument. For the latest information on available option upgrades, see

ektronix Web site.

the T

6 RSA6100A Series R eal-Time Spectrum Analyzers Help

About Tektronix Spectrum Analyzers > Documentation and Support

Documentation

In addition to the online help, the following documents are available:

Quick Start User Manual (071-1909-XX - English). The Quick Start User Manual has information about installing and operating your instrument. The Quick Start User Manual is also available in Simpliﬁed Chinese (071-1910-XX), Japanese (071-1911-XX), and Russian (071-1912-XX).

Application Examples Reference (071-2590-XX). The Application Examples Reference provides examples of speciﬁc application problems and how to solve those problems using an RSA6100A Series spectrum analyzer.

Programmer Manual (077-0249-XX). The Programmer Manual is provided as a printable PDF ﬁle, which is located on the Documents CD. See the Documents CD-ROM for installation information. The Programmer manual is also available in printed form as an optional accessory.

Service Manual (077-0250-XX). The Service manual is provided as a printable PDF ﬁle, which is located on the Documents CD. See the Documents CD-ROM for installation information. The Service manual system.

includes procedures to service the instrument to the module level and restore the operating

Documentation

ﬁcations and Performance Veriﬁcation Technical Reference Manual (077-0251-XX). This is

Speci

a PDF-only manual that includes both the speciﬁcations and the performance veriﬁcation procedure. It is located on the Documents CD.

Declassiﬁcation and Security Instructions (077-0170-XX) This document helps customers with data security concerns to sanitize or remove memory devices from the RSA6100A Series Real-Time Spectrum Analyzers. It is located on the Documents CD.

The most recent versions of the product documentation, in PDF format, can be downloaded from

ww.tektronix.com/manuals. You can ﬁnd the manuals by searching o n the product name.

Other Documentation

Your instrument includes supplemental information on CD-ROM:

Documents CD (Tektronix part number 063-3930-XX)

RSA6100A Series Real-Time Spectrum Analyzers Help 7

Orientation Front Panel Connectors

Front Panel Connectors

Item

2TrigIn

xxx

Connector

Trig Out Trigger output connector. 50 Ω, BNC, High > 2.0 V, Low < 0.4 V, (output

USB 1.1 USB 1.1 Mouse connector.

USB 2.0 USB 2.0 connector.

RF Input

Front-Panel Controls

Description

current 1 mA).

External Trigger input connector, –2.5 V to +2.5 V (user settable).

RF input connector 50 Ω.

8 RSA6100A Series R eal-Time Spectrum Analyzers Help

Orientation Front-Panel Controls

Reference

Item Function Menu Equivalen

1 Media DVD-RW or remo

drive.

2 Displays

Opens the Displays dialog box enabling you to select which displays to o

Settings Opens/clos

pen.

es the Settings control

panel for the selected display.

4 Trigger

Opens/closes the Trigger control panel.

Acquire

Opens/closes the Acquire control panel.

6 Analysis

Opens/cl

oses the Analysis control

panel.

Freq Press to

adjust the measurement

frequency.

Span (Spectrum)

o adjust the span or press

Press t and hold to display the Freq & Span control panel for the General Signal

g displays.

Viewin

9 Amplitude

/closes the Amplitude control

Opens panel.

BW (Spectrum)

to adjust the bandwidth or

Press press and hold to display the BW control panel for the General Signal

ing displays.

View

xxx

vable hard disk

Setup > Displays

Setup > Sett

ings

Setup > Trigger

Setup > Acquire

Setup > An

alysis

Setup > Analysis > Frequency

> Amplitude

Setup

RSA6100A Series Real-Time Spectrum Analyzers Help 9

Orientation Front-Panel Controls

Reference

11 Tab Moves the curs

Item Function Menu Equivalen

or to the next entry in the dialog box or control panel. Same as pressing the Tab key on an

oard.

ops acquisitions.

k of the trace in the

12 Run

Peak (Marke section)

external keyb

Starts and st

Moves the active marker to the maximum pea selected display. If markers are turned off, the marker reference (MR)

at the maximum peak.

e next marker. If markers

Select (Ma section)

rkers

will appear

Selects th are turned off, the MR marker (marker reference) will appear.

Deﬁne (Markers section)

Opens the Markers control panel. If marker

s are turned off, the MR

marker (reference) will appear.

16 Esc Exits a d

ialog box without saving changes: the same as Esc on an external keyboard.

Control knob Changes values in numeric and list

ls. Pressing the knob (clicking

contro it) is the same as pressing the Enter key on a keyboard.

18 Arrow keys Move the Markers. The Up arrow

moves the selected marker to the

ighest peak. The down arrow

next h moves the selected marker to the next lower peak value. The right and

arrows move the selected marker

left to the next peak.

xxx

Run > Start Ru

Markers > Peak

n>Stop

Reference

Item Function Menu Equivalent

19 Keypad Enters values in numeric controls.

20 Enter

Completes data entry in controls. Same as pressing the Enter key on an external keyboard.

xxx

10 RSA6100A Series Real-Time Spectrum Analyzers Help

Orientation Touch Screen

Reference

21 Recall

24 Help Displays the online help.

25 Print Displays the Print dialog box. File > Print

26 Preset

xxx

Touch Screen

You can use touch to control the instrument in addition to the front-panel controls, mouse, or extended keyboard. Generally, touch can be used anywhere that click is mentioned in this online help.

To disable the touch screen, push the front-panel TouchScreenOffbutton. When the touch screen is off, the button is lighted. You can still access the on-screen controls with a mouse or keyboard.

You can adjust the touch screen operation to your personal pre ferences. To adjust the touch screen settings, from Windows, select Start > Control Panel > Touch Screen Calibrator.

Item Function Menu Equiva

Opens the Recall dialog box.

Save Opens the Save As dialog box. File > Save As

Touch Screen Off Turns the touch screen on and off. It

is off when lighted.

Returns the instrument to the default or preset values.

File > Recal

Help > Online Manual

Setup > Preset

lent

NOTE. If the instrument is powered on in Windows Safe M ode, the touch screen is inoperative. You will

eed to use a mouse or keyboard to restore normal operation.

Touch-Screen Actions

You can use the touch screen to change marker settings and how waveforms are displayed by using the Touch-screen Actions menu.

RSA6100A Series Real-Time Spectrum Analyzers Help 11

Orientation Touch-Screen Actions

To use the Touch-screen Actions menu, touch the display in a graph area and hold for one second, then remove your ﬁnger. You can also use a mouse to display the Touch-screen Action menu by clicking the right

mouse button.

12 RSA6100A Series Real-Time Spectrum Analyzers Help

Orientation Touch-Screen Actions

Icon Menu Description

Select Selects marke

rs and adjusts their position.

Span Zoom

CF Pan Adjusts the Center Frequency according to horizontal movement.

Zoom

Pan

Reset Scale

Marker to peak

Next Peak

Add marker

Delete marker Removes the last added marker.

All markers off

Trigger On This Use to visually deﬁne trigger parameters in the DPX Spectrum

xxx

Touch-Screen Menu for Spurious Display

Zooms the graph area about the selected point. Touch the graph display at a point of interest and drag to increase or decrease the span about the point of interest. Span Zoom adjusts the span control and can affect the acquisition bandwidth.

Adjusts horizontal and vertical scale of the graph. The ﬁrst direction with enough movement becomes the primary scale of adjustment. Adjustment in the secondary direction does not occur until a threshold of 30 pixels of movement is crossed.

Dragging to the left or down zooms out and displays a smaller waveform (increases the scale value). Dragging to the right or up zooms in and displays a larger waveform (decreases the scale value).

Adjusts horizontal and vertical position of the waveform. The ﬁrst direction with enough movement becomes the primary direction of movement. Movement in the secondary direction does not occur until a threshold of 30 pixels of movement is crossed.

Returns the horizontal and vertical scale and position settings to their default v alues.

Moves the selected marker to the highest peak. If no marker is turned on, this control automatically adds a marker.

Moves the selected marker to the next peak. Choices are Next left, Next right, Next lower (absolute), and Next higher (absolute).

Deﬁnes a new marker located at the horizontal center of the graph.

Removes all markers.

display.

The Touch-screen actions menu in the Spurious display has some minor changes compared to the standard version used in other displays.

RSA6100A Series Real-Time Spectrum Analyzers Help 13

Orientation Elements of the Display

Icon Menu Description

xxx

Single-range Changes the current multi-range display to a single range display.

The displayed range is the range in which you display the touchscreen-actions menu. Selecting Single-range from the menu is equivalent to selecting Single on the Settings > Parameters tab.

Multi-range

Marker -> Sel Spur

Changes the current single-range display to a multi-range display. Selecting Multi-range from the menu is equivalent to selecting Multi on the Settings > Parameters tab.

Moves the selected marker to the selected spur.

Elements of the Display

The main areas of the application window are shown in the following ﬁgure.

14 RSA6100A Series Real-Time Spectrum Analyzers Help

Orientation Elements of the Display

Speciﬁc elements of the display are shown in the following ﬁgure.

RSA6100A Series Real-Time Spectrum Analyzers Help 15

Orientation Elements of the Display

16 RSA6100A Series Real-Time Spectrum Analyzers Help

Orientation Elements of the Display

Ref

Setting

Description

number

1 Displays

Opens the Select Displays dialog box so that you can select measurement displays.

2Markers

Settings Opens the Se

Opens or clos

es the Marker toolbar at the bottom of the window.

ttings control panel for the selected display. Each display has

its own control panel.

4 Trigger

Acquire

6 Analysis

Opens the Trigger control panel so that you can deﬁne the trigger settings.

Opens the Acquire control panel so that you can deﬁne the acquisition settings.

Opens the Analysis control panel so that you can deﬁne the analysis settings such as frequency, analysis time, and units.

Frequency

Displays the frequency at which measurements are made. For spectrum

s, this is called “Center Frequency”. To change the value, click the

display text and use the front panel knob to dial in a frequency. You can also enter a frequency with the front panel keypad or use the front panel up and down

buttons

Refere

nce Level

ys the reference level. To change the value, click the text and enter a

Displa number from the keypad or use the front panel up and down buttons.

9Ampli

tude

Opens the Amplitude control panel so that you can deﬁne the Reference Level, conﬁgure internal attenuation, and enable/disable the (optional) Preampliﬁer.

10 Replay Runs a new measurement cycle on the last acquisition data record using any

new settings.

11 Run

Starts and stops data acquisitions. W hen the instrument is acquiring data, the

on label has green lettering. When stopped, the label has black lettering.

butt You can specify the run conditions in the Run menu. For example, if you select Single Sequence in the Run menu, when you click the Run button,

instrument will run a single measurement cycle and stop. If you select

the Continuous, the instrument will run continuously until you stop the acquisitions.

Check mark indicator The check mark indicator in the upper, left-hand corner of the display indicates

the display for which the acquisition hardware is optimized.

xxx

RSA6100A Series Real-Time Spectrum Analyzers Help 17

Orientation Rear-Panel Connectors

Rear-Panel Co

Item Description

4,5

8Trig2ln

16 Ethernet network connector

xxx

nnectors

AC Input, main power connector

GPIB

IF Output (optional)

Real Time IQ Output (optional)

+28 V DC Output, switched

Headphone, audio output connector

COM 2, serial port for connecting peripherals

VGA external monitor output

PS2 keyboard input

USB2.0 ports for mouse and other peripherals (printers, external hard disks)

TekLink - reserved for future use

Ref Out, reference frequency output

Ref In, reference frequency input

Setting Up Network Connections

Because the instrument is based on Windows XP, you conﬁgure network connections for the instrument the same way you would for any PC based on Windows XP. See Help and Support in the Windows Start menu to access the Windows Help System for information on setting up network connections.

18 RSA6100A Series Real-Time Spectrum Analyzers Help

Operating Your Instrument Restoring Default Settings

Restoring D efault Settings

To restore the instrument to its factory default s

Select File > Preset to return the analyzer to its default settings.

Preset resets all settings and clears all acquisition data. Settings and acquisition data that have not been saved will be lost.

Running Alignments

Alignments are adjustment procedures. Alignments are run by the instrument using internal reference signals and measurements and do not require any external equipment or connect

There are two settings for Alignments:

Automatically align as needed

Run alignments only when the Align Now button is pressed

If Automatically align as needed is selected, alignments run whenever the spectrum analyzer detects asufﬁcient change in ambient conditions to warrant an alignment.

If Run alignments only when "Align Now" button is pressed is selected, the spectrum analyzer never runs an alignment unless you manually initiate an alignment using the Align Now button.

ettings:

ions.

NOTE. There are a few critical adjustments that must run occasionally even if Automatically align is not enabled.

Alignment Status

When the spectrum analyzer needs to run an alignment, it displays a message on screen. If no message is displayed, you can assume that the spectrum analyzer is properly aligned.

NOTE. If you must use the instrument before it has completed its 20-minute warm-up period, y ou should perform an alignment to ensure accurate measurements.

Initiating an Alignment

1. Select Setup > Alignments.

2. Select the Align Now button.

RSA6100A Series Real-Time Spectrum Analyzers Help 19

Operating Your Instrument Application Presets

The spectrum an alignment procedure is running. If the instrument fails the alignment procedure, an error message will be displayed. If the instrument fails an alignment, run Diagnostics (Tools > Diagnostics) to see if you can determine why the alignment failed.

NOTE. While an alignment is running, both the IF and IQ outputs are disabled.

Alignments during warm-up. During the 20-minute warm-up period, the spectrum analyzer will use the

alignment data generated during the previous use of the instrument as it warms to operating temperature (if Auto mode is selected). During the speciﬁed period for warm-up, the instrument performance is not warrante

Alignments during normal operation. Once the spectrum analyzer reaches operating temperature, a n

alignment will be run. If an alignment becomes necessary during a measurement cycle (if Auto mode is selected), the measurement is aborted and an alignment procedure is run. Once an alignment procedure is completed, the measurement cycle restarts.

NOTE. The ﬁrst time the instrument runs after a software upgrade (or reinstall), the instrument will perform a full alignment after the 20–minute warm-up period. This alignment c annot be aborted and it occurs even if alignments are set to run only when manually initiated.

alyzer will run an alignment procedure. Status messages are displayed while the

Alignments Are Not Calibrations

Alignments are adjustment procedures run by the instrument using internal reference signals and measurements. Calibrations can only be performed at a Tektronix service center and require the use of traceable test equipment (signal sources and measuring eq instrument.

Application Presets

Menu Bar: File > Application Presets

The spectrum analyzer includes a set of conﬁguration ﬁles that are tailored to speciﬁc applications. These conﬁguration ﬁles, referred to as Application Presets, open selected displays and load settings that are optimized to address speciﬁc application requirements. You can add to the default application presets by creating your own application presets. See C application presets through the Application Presets menu item.

To load an application preset:

1. Select File > Application Presets. This opens the Applications Presets dialog window.

2. Select the application preset that suits your needs.

3. Click OK to recall the application preset.

uipment) to verify the performance of the

reating Ap plication Presets (see page 24). You access the

20 RSA6100A Series Real-Time Spectrum Analyzers Help

Operating Your Instrument Application Presets

Application Pr

Modulation Analysis The Modulation Analysis setup application preset provides you with the most common

Pulse Analysis The Pulse Analysis application preset provides you with the most common displays

Spectrum Analyzer The Spectrum Analysis application presets provide you with the settings commonly used

Time-Frequency Analysis

xxx

eset

Description

displays used

used during pu better optimized for pulsed signal analysis. Option 20 is required to use the pulse measurements applications preset.

for general

The Time-Fr signal behavior over time.

during modulation analysis.

lse analysis, and makes changes to the default parameters to s ettings

purpose spectrum analysis.

equency preset conﬁgures the instrument with settings suited to analyzing

Modulation Analysis

The Modul

DPX Spectrum Display: Shows you a continuous spectrum monitoring of the speciﬁed carrier frequen

Signal Quality: Shows a summary of modulation quality measurements (EVM, rho, Magnitude Error,

Constellation: Shows the I and Q information of the signal analyzed in an I v s. Q format.

ation Analysis application preset opens the following displays:

cy.

Phase Error, and others).

Symbol Table: Shows the demodulated symbols of the signal.

To use the Modulation Analysis preset:

1. Select File > Application Presets > Modulation Analysis. Click OK.

2. Set the measurement frequency using the front-panel knob or keypad. Your signal should appear in

the DPX spectrum display.

3. Set the reference level so that the peak of your signal is about 10 dB below the top of the DPX spectrum display.

4. Set the modulation parameters for your signal. This includes the Modulation Type, Symbol Rate, Measurement F ilter, Reference Filter and Filter Parameter. All of these settings are accessed by pressing the Settings button.

For most modulated signals, the Modulation Analysis application preset should present a stable display of modulation quality. Additional displays can be added by using the Displays button, and other settings can be modiﬁed to better align with your signal requirements.

Pulse Analysis

The Pulse Analysis application preset opens the f ollowing displays:

DPX Spectrum: The DPX spectrum display is opened with the maximum available span.

Time Overview: Shows amplitude vs. time over the analysis period.

RSA6100A Series Real-Time Spectrum Analyzers Help 21

Operating Your Instrument Application Presets

Pulse Trace: Sh the pulse table.

Pulse Measurement Table: This shows a full report for the user-selected pulse measurements.

You can make a selected pulse and measurement appear in the Pulse Trace display by highlighting it in the Pulse Measurement Table. Key pulse-related parameters that are set by the Pulse Analysis application preset are:

Measurement Filter: No Filter.

Measurement Bandwidth: This is set to the maximum real-time bandwidth of the instrument (40 MHz in a base instrument or 110 MHz with instruments with Option 110). Note: The label on the “Measurement Bandwidth” setting is just “Bandwidth”. Like the main instrument Preset command and the other application presets, the Pulse Analysis application preset also sets most other instrument controls to default value

Analysis Period: This is set to 2 ms to ensure a good probability of catching several pulses for typical signals.

To use the Pulse Analysis preset:

1. Select File > Application Presets > Pulse Analysis. Click OK.

2. Set the Center Frequency control to the carrier frequency of yo

3. Set the Reference Level to place the peak of the pulse signal approximately 0-10 dB down from

thetopoftheTimeOverviewdisplay.

ows the trace of the selected pulse and a readout of the selected measurement from

ur pulsed signal.

You may need to trigger on the signal to get a more stable display. This is set up in the Trigger control panel. (“Trig” button). Using the Power trigger type with the RF Input source works well for many pulsed signals.

4. Set the Analysis Period to cover the number of pulses in your signal that you want to analyze. To do this, click in the data entry ﬁeld of the Time Overview window and set the analysis length as needed.

Spectrum Analysis

The Spectrum Analysis application preset opens a Spectrum display and sets several parameters. There are two presets are available for spectrum analysis, as follows.

Spectrum Analysis (0.1- 6.2 GHz): This sets the frequency range to 0.1 to 6.2 GHz, and sets RF/IF optimization to Minimize Sweep Time. This a pplication preset is conﬁgured for use with the RSA6106A, but it can be also used with the RSA6114A.

Spectrum Analysis (0.1-14 GHz): This sets the frequency range to 0.1 to 14 GHz, and sets the RF/IF optimization to Minimize Sweep Time. This a pplication preset is conﬁgured for use with the RSA6114A. If you use this preset on the RSA6106A, you will have to manually adjust the center frequency and span. If you have Option 110 installed in your instrument, using Minimize Sweep Time will improve the screen update rate for wide spans approximately 3X compared to the auto settings. If Option 110 is not installed, no improvement in sweep speed is gained by minimizing sweep time.

To use the either of the spectrum analysis application presets:

22 RSA6100A Series Real-Time Spectrum Analyzers Help

Operating Your Instrument Application Presets

1. Select File > Ap (0.1-6.2 GHz) as appropriate. Click OK.

2. Set the measur

3. Adjust the span to show the necessary detail.

plication Presets > Spectrum Analysis (0.1-14 GHz) or Spectrum Analysis

ement frequency using the front-panel knob or keypad.

Time-Frequency Analysis

The Time-Fr

Time Overview: Shows a time-domain view of the analysis time ‘window’.

Spectrogram: Shows a three-dimensional view of the signal where the X-axis represents frequency, the Y-axis represents time, and color represents amplitude.

Frequency vs. Time: This display’s graph plots changes in frequency over time and allows you to make marker measurements of settling times, frequency hops, and other frequency transients.

Spectrum: Shows a spectrum view of the signal. The only trace showing in the Spectrum graph after selecting the Time-Frequency Analysis preset is the Spectrogram trace. This is the trace from the Spe because its easier to work with stable results. In the Spectrogram display, move a marker up or down to see the spectrum trace at various points in time.

Theanalysisperiodissetto5ms.

equency Analysis application preset opens the following displays:

ctrogram display that is selected by the active marker. Stop acquisitions with the Run button

e the Time-Frequency application preset:

To us

1. Select File > Application Presets > Time-Frequency Analysis. Click OK.

2. When the preset’s displays and settings have all been recalled and acquisitions are running, adjust the

center frequency and span to capture the signal of interest.

3. Set the Reference Level to place the peak of the signal approximately 0-10 dB down from the top of the Spectrum graph.

4. If the signal is transient in nature, you might need to set a trigger to capture it. For more information on triggering in the time and frequency domain, see T

When the signal has been captured, the spectrogram shows an overview of frequency and amplitude changes over time. To see frequency transients in greate r detail, use the Frequency vs. Time display.

The Time-Frequency Analysis preset sets the analysis period to 5 ms. The Spectrum Span is 40 MHz. The RBW automatically selected for this Span is 300 kHz. For a 300 kHz RBW, the amount of data needed for a single spectrum transform is 7.46 μs. A 5 ms Analysis Length yields 671 individual spectrum transforms, each one forming one trace for the Spectrogram to display as horizontal colored lines. This preset scales the Spectrogram time axis (vertical axis) to -2, which means that the Spectrogram has done two levels of time compression, resulting in one visible line for each four transforms. This results in 167 lines in the Spectrogram for each acquisition, each covering 29.84 μs.

riggering (see page 316)

RSA6100A Series Real-Time Spectrum Analyzers Help 23

Operating Your Instrument Setting Options

Creating Appli

You can add your own application presets to the list that appears in the Application Presets dialog box. Create a Setup the ﬁle will be shown in the Application Presets list along with the sets provided by Tektronix. For instructions on how to save a Setup ﬁle, see S

If the Tektronix application presets ﬁles are accidentally deleted, you can restore them by reinstalling the RSA6100A software. The software installation process will not remove user ﬁles you have placed in the Application Presets directory.

Setting Options

Menu Bar: Tools > Options

There are several settings you can change that are not related to measurement functions. The Option settings control panel is used to change these settings.

cation Presets

ﬁleandsaveacopyofittoC:\RSA6100A Files\Application Presets. The name you give

aving Data (see page 333).

Settings tab

Save and Export Use this tab to specify whether or not save ﬁles are named automatically and what

GPIB Use this tab to set the primary GPIB address for the instrument.

Security Selecting the Hide Sensitive readouts check box causes the instrument to replace

Colors Use this tab to select different color schemes for the measurement graphs.

xxx

Description

information is saved in acquisition data ﬁles.

measurement readouts with a string of asterisks.

Save and Export

The Save and Export tab allows you to specify whether or not ﬁles are saved with an automatically generated name, and how much data is saved in an acquisition data ﬁle.

24 RSA6100A Series Real-Time Spectrum Analyzers Help

Operating Your Instrument Setting Options

All Files — The A

ﬁles by appending a number to a base ﬁle name. Use this tab to enable/disable automatic naming of ﬁles. For example, if Automatically Increment Filename Number is disabled, when you select Save

from the File menu, you will have to enter a name for the ﬁle.

Acquisition data ﬁles — This setting speciﬁes whether saved data ﬁles include the entire acquisition record or only the data for the analysis length (a subset of the acquisition record).

TIQ acquisition data ﬁles — Speciﬁes which data records to save. You can choose from the following:

Current acquisition: Saves the current acquisition.

Current fr one most recently analyzed.

Selected

All in history: Saves all acquisition records in the history.

utomatically increment ﬁlename/number function can automatically name saved

ame: If Fast Frame is enabled, saves only the current frame. The current frame is the

frames: If Fast Frame is enabled, saves the speciﬁed frames.

Colors

The Col setting does not change the overall instrument application or Windows color scheme.

or scheme setting provides three color schemes for the measurement graphs. The color scheme

erstorm — This scheme displays graphs in shades of blue. This provides a less vibrant color

Thund scheme than the default setting.

zard—Thisschemedisplaysgraphswithawhite background to save ink when printing.

Bliz

Classic — The default setting. This scheme displays the graph area with a black background.

RSA6100A Series Real-Time Spectrum Analyzers Help 25

Using t he Mea surement Displa ys Selecting Displays

Selecting Displays

Menu Bar: Setup > Displays

Application Toolbar: Displays

Use the Sele

To sel

1. Press the Displays button or select Setup > Displays.

ct Displays dialog to choose the displays that appear on the screen.

ect displays:

2. Select one of the choices under Folders. The folder chosen determines the choices available in Available displays.

3. Double-click the desired display in the Available displays box or select the desired display and click Add.

4. Click OK.

teractions Between Displays

Different displays can require different settings, for example acquisition bandwidth, analysis length, or

esolution bandwidth, to achieve optimum results. The instrument automatically adjusts some settings

r to optimize them for the selected display. The check mark indicator in the upper, left-hand corner of the display indicates the display for which the acquisition hardware is optimized. Depending on instrument settings, some displays might stop displaying results if they are not the selected display.

26 RSA6100A Series Real-Time Spectrum Analyzers Help

Taking Measurements > Measurements Available Measurements

Available Measurements

The automatic measurements available include RF power measurements, analog modulation measurements, digital modulation measurements, and pulse measurements.

Power Measurements

Measurement Description

Channel Power The total RF power in the selected channel (located in the ACPR display).

Adjacent Channel Power Ratio Measure of the signal power leaking from the main channel into adjacent channels.

Multi-Carrier Power Ratio The ratio of the signal power in the reference channel or group of channels to the power

in adjacent channels.

Peak/Avg Ratio Ratio of the peak power in the transmitted signal to the average power in the transmitted

located in the CCDF display).

signal (

CCDF The Comp

time a signal spends at or above a given power level relative to the average power of a measured signal.

xxx

lementary Cumulative Distribution Function (CCDF). CCDF shows how much

RSA6100A Series Real-Time Spectrum Analyzers Help 27

Taking Measurements > Measurements Available Measurements

Digital Modula

tion Measurements

Measurements for all modulation types except nFSK, C4FM, OQPSK and SOQPSK

Measurement Description

EVM

Phase Error

Mag Error

MER (RMS) The MER is deﬁned as the ratio of I/Q signal power to I/Q noise power; the result is

IQ Origin Offset The magnitude of the DC offset of the signal measured at the symbol times. It indicates

Frequency Error

Gain Imbalance The gain difference between the I and Q channels in the signal generation path.

Quadrature Error The orthogonal error between the I and Q channels. The error shows the phase

Rho

xxx

The normalized RMS value of the error vector between the measured signal and the ideal reference signal over the analysis length. The EVM is generally measured on symbol or chip instants and is reported in units of percent and dB. EVM is usually measured after best-ﬁt estimates of the frequency error and a ﬁxed phase offset have been removed. These estimates are made over the analysis length. Displays RMS and Peak values with location of Peak value.

The RMS phase difference between the measured signal and the ideal reference signal. Displays RMS and Peak values with location of Peak value.

The RMS magnitude difference between the measured signal and the reference signal magnitude. Displays RMS and Peak values with location of Peak value.

indicated in dB.

the magnitude of the carrier feed-through signal.

The frequency difference between the measured carrier frequency of the signal and the user-selected center frequency of the instrument.

Constellations with gain imbalance show a pattern with a width that is different form height.

difference between I and Q channels away from the ideal 90 degrees expected from the perfect I/Q modulation. Not valid for BPSK modulation type.

The normalized correlated power of the measured signal and the ideal reference signal. Like EVM, Rho is a measure of m odulation quality. The value of Rho is less than 1 in all practical cases and is equal to 1 for a perfect signal measured in a perfect receiver.

28 RSA6100A Series Real-Time Spectrum Analyzers Help

Taking Measurements > Measurements Available Measurements

Measurements f

or OQPSK and SOQPSK modulation types

Measurement Description

EVM

The normalize

d RMS value of the error vector between the measured signal and the ideal reference signal over the analysis length. The EVM is generally measured on symbol or chip instants and is reported in units of percent and dB. EVM is usually measured after best-ﬁtesti

mates of the frequency error and a ﬁxed phase offset have been removed. These estimates are made over the analysis length. Displays RMS and Peak values with location of Peak value.

Offset EVM Offset EVM is like EVM except for a difference in the time alignment of the I and Q

samples. Fo

r EVM, I and Q samples are collected at the same time, for every symbol decision point (twice the symbol rate for offset modulations). For Offset EVM, the I and Q symbol decision points are time-aligned before collecting the I and Q samples. In this case, one I

and one Q sample is collected for each symbol (half as many samples as the

same number of symbols for (non-offset) EVM.

Phase Erro

The RMS phase difference between the measured signal and the ideal reference signal. Displays RMS and Peak values with location of Peak value.

Mag Error

MER (RMS

)

The RMS magnitude difference between the measured signal and the reference signal

de. Displays RMS and Peak values with location of Peak value.

magnitu

The MER i

sdeﬁned as the ratio of I/Q signal power to I/Q noise power; the result is

indicatedindB.

IQ Origin Offset The magnitude of the DC offset of the signal measured at the symbol times. It indicates

the magnitude of the carrier feed-through signal.

Frequency Error

Imbalance

Gain

The frequency difference between the measured carrier frequency of the signal and the

selected center frequency of the instrument.

user-

ain difference between the I and Q channels in the signal generation path.

The g Constellations with gain imbalance show a pattern with a width that is different form height.

Quadrature Error The orthogonal error between the I and Q channels. The error shows the phase

ference between I and Q channels away from the ideal 90 degrees expected from the

dif perfect I/Q modulation. Not valid for B PSK modulation type.

Rho

The normalized correlated power of the measured signal and the ideal reference signal. Like EVM, Rho is a measure of modulation quality. The value of Rho is less than 1 in all

actical cases and is equal to 1 for a perfect signal measured in a perfect receiver.

xxx

RSA6100A Series Real-Time Spectrum Analyzers Help 29

Taking Measurements > Measurements Available Measurements

Measurements f

or nFSK modulation types

Measurement Description

Peak FSK err Peak value of t

RMS FSK Err RMS value of t

Peak Mag Err

The Peak mag

he frequency deviation error at the symbol point.

nitude difference between the measured signal and the reference signal

magnitude.

RMS Mag Err The RMS magnitude difference between the measured signal and the reference signal

magnitude.

Freq Error

Freq Deviation

Symbol R

ate Error

The frequency difference between the measured carrier frequency of the signal and the user-sele

Frequenc

This com

cted center frequency of the instrument.

y distance from the center frequency at the symbol point.

pares the user-entered symbol rate to the instrument calculated symbol rate of

the analyzed signal.

Symbol Rate When in Auto-symbol rate, the instrument calculates the symbol rate of the signal and

the instrument calculates the error between the user entered value and the instrument

ated value.

calcul

xxx

rements for C4FM modulation type

Measu

rement

Measu

rror Magnitude

RMS E

ier Frequency Error

Carr

Deviation

Length

xxx

iption

Descr

alue of the frequency deviation error at the symbol point.

RMS v

uency difference between averaged signal frequency and the center frequency.

Freq

quency distance from the center frequency at the symbol point.

Fre

ber of symbols in the analysis area.

Num

Analog Modulation Measurements

Measurements for AM modulation

Measurement Description

ositive peak AM value.

-AM Negative peak AM value.

Total AM Total AM value, which is equal to the peak-peak AM value divided by 2.

xxx

30 RSA6100A Series Real-Time Spectrum Analyzers Help

Taking Measurements > Measurements Available Measurements

Measurements f

or FM modulation

Measurement Description

+Pk

–Pk

Positive peak

Negative pea

RMS RMS value of

Pk-Pk/2 Peak-to-pe

Pk-Pk

xxx

Peak-to-p

frequency deviation.

k frequency deviation.

the frequency deviation.

ak frequency deviation divided by 2.

eak frequency deviation.

Measurements for PM modulation

Measurement Description

+Pk Positive peak phase deviation.

–Pk Negative peak phase deviation.

RMS RMS value of the phase deviation.

Pk-Pk Peak-to-peak phase deviation.

xxx

Pulse Measurements

Measurement Description

Average ON Power

Peak Power Maximum power during pulse on.

Average Transmitted Power The average power transmitted, including both the time the pulse is on and the time

Pulse Width

Rise Time

Fall Time

Repetition Interval

Repetition Rate

Duty Factor (%) The ratio of the width to the pulse period, expressed as a percentage.

Duty Factor (Ratio) The ratio of the pulse width to the pulse period.

Ripple Ripple is the peak-to-peak ripple on the pulse top. It does not include any preshoot,

The average power transmitted during pulse on.

it is off, and all transition times.

The time from the rising edge to the falling edge at the –3 dB / –6 dB level (50%) of the user selected 100% level. Level is user selectable for Volts or Watts.

The time required for a signal to rise from 10% to 90% (or 20% to 80%) of the user selected 100% level.

The time required for a signal to fall from 90% to 10% (or 80% to 20%) of the user selected 100% level.

The time from a pulse rising edge to the next pulse rising edge.

The inverse of repetition interval.

overshoot, or undershoot. By default, the ﬁrst 25% and the last 25% of the pulse top is excluded from this measurement to eliminate distortions caused by these portions of the pulse.

If the Amplitude units selected in the Amplitude panel (affects all amplitude measurements for the analyzer) are linear, the Ripple results will be in %Volts. For log units, the Ripple results will be in %Watts. The default for the general Units control is dBm, so the Ripple results default is %Watts.

See also R

ipple (see page 391).

RSA6100A Series Real-Time Spectrum Analyzers Help 31

Taking Measurements > Measurements Available Measurements

Measurement Description

Ripple dB The Ripple measurement expressed in dB .

Droop

Droop dB The Droop mea

Overshoot The amount b

Overshoot dB The Overshoot measurement expressed in dB.

Pulse-Pulse Phase Difference The phase difference between the selected pulse and the ﬁrst pulse in the a nalysis

Pulse-Pu

lse Freq Difference

RMS Freq Error The RMS Frequency Error measurement is the RMS average of the Freq Error vs. Time

Max Freq Error

RMS Phase Error The RMS Phase Error measurement is the RMS average of the Phase vs Time trace,

Max Phase Error

q Deviation

Fre

Phase Deviation

Impulse Response Amplitude

Impulse Response Time

Time

xxx

Droop is the power difference between the beginning and the end of the pulse On time. A straight-lin

e best ﬁt is used to represent the top of the pulse. The result is a percentage

referenced to the Average ON Power.

surement expressed in dB.

y which the signal exceeds the 100% level on the pulse rising edge. Units

are %Watts or %Volts.

window. The instantaneous phase is measured at a user-adjustable time following the rising ed

The diffe

ge of each pulse.

rence between the frequency of the current pulse and frequency of the previous pulse. The instantaneous frequency is measured at a user-adjustable time following the rising edge of each pulse.

computed over the Measurement Time.

trace,

The max

imum frequency error is the difference between the measured carrier frequency of the signal and the user-selected center frequency of the analyzer.

computed over the Measurement Time.

The phase is measured at each point during the pulse’s ON time. The phase error for

point is the difference between the measured phase v alue and the calculated ideal

each phase value. After the phase error is calculated for all points in the acquisition record, the largest error in the positive direction and the largest in the negative direction are

rmined. Whichever of these two values has the greater absolute value is designated

dete the Max Phase Error.

The Frequency Deviation measurement is the difference between the maximum and minimum measured values of the signal frequency during the Measurement Time.

The Phase Deviation is the difference between the maximum and minimum Phase values

asured during the ON time of a pulse.

he difference in dB between the levels of the main lobe and highest side lobe.

he difference in time between the main lobe and highest side lobe.

This is the time in seconds relative to the time reference point in the ﬁrst acquisition record in the data set.

32 RSA6100A Series Real-Time Spectrum Analyzers Help

General Signal Viewing Overview

Overview

The displays in the General Signal Viewing folder (Displays > Folders > General Signal Viewing) are:

Amplitude vs Time

DPX Spectru

Frequency vs Time

Phase vs Time

RF I & Q vs Time

Spectrogram

Spectrum

Time Ove

These displays provide extensive time-correlated multi-domain views that connect problems in time,

ncy, phase and amplitude for enabling you to more quickly understand cause and effect when

freque troubleshooting.

rview

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General Signal Viewing > DPX Spectrum DPX Primer

DPX Primer

With the DPX Spectrum display you can detect and accurately measure transients as brief as 10.3 µs. The instrument computes up to 292,000 spectrums per second (with Option 200; up to 48,833 without Option

200) of the digitized input signal. Then it displays all these spectrums as a color-graded bitmap that reveals low-amplitude signals beneath stronger signals sharing the same frequency at different times.

The strong signal in the DPX spectrum graph, shown in Figure 1, is a repeating pulse at a ﬁxed frequency. There is also a lower-power CW signal that steps very quickly through the same span. During the pulse’s on time, th envelope shape. But during the time the pulse is off, the sweeping signal is detected and shown in its true form. Both signals are visible in the bitmap because at least one full cycle of their activities occurs within a single DPX display update.

e power of the two signals is additive, resulting in nearly undetectable differences in the pulse

Figure 1

Compare the display of a traditional swept spectrum analyzer (Figure 2) and that of a real-time spectrum analyzer with a DPX spectrum display (Figure 3). The signal captured is a typical WLAN interchange between a nearby PC and a more-distant network access point (AP). The laptop signal is nearly 30 dB stronger than the AP’s signal because it is closer to the measuring antenna.

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Figure 2

Figure 3

The traditional swept spectrum analyzer display, Figure 2, uses line traces that can show only one level for each frequency point, representing the largest, the smallest or the average power. After many sweeps, the Max Hold trace shows a rough envelope of the stronger laptop signal. +Peak detection was selected for the

r trace in an attempt to capture the weaker but more frequent AP signal, but the bursts are very brief,

othe so the likelihood of seeing one in any particular sweep is small. It will also take a long time to statistically capture the entire spectrum of a bursted signal due to the architecture of the swept spectrum analysis.

The DPX spectrum display, Figure 3, reveals much more insight on the s ame signal. Since it is a bitmap image instead of a line trace, you can distinguish many different signals occurring within each update period and/or different version of the same signal varying over time. The heavy band running straight across the lower third of the graph is the noise background when neither the laptop nor the AP is transmitting. The red lump of energy in the middle is the ON shape of the AP signal. Finally, the

oredelicatespectrumabovetheothersisthelaptop transmissions. In the color scheme used for this

m demonstration (“Temperature”), the hot red color indicates a signal that is much more frequent than signals shown in cooler colors. The laptop signal, in yellow, green and blue, has higher amplitude but doesn’t occur nearly as often as the AP transmissions because the laptop was downloading a ﬁle when this screen capture was taken.

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General Signal Viewing > DPX Spectrum DPX Primer

How DPX Works

This section explains how DPX spectrum displays are created. The input RF signal is conditioned and down-converted as usua FPGA that computes very fast spectral transforms, and the resulting frequency-domain waveforms are rasterized to create the bitmaps.

The DPX bitmap that you see on screen is composed of pixels representing x, y, and z values for frequency, amplitude, and hit count (instruments with Option 200 provide Density as the z-axis value in place of hit count). A multi-stage process, shown in Figures 4a - 4d, creates this bitmap, starting with analog-to-digital conversion of the input signal.

Simpliﬁed Flow of Multi-stage Processing from RF Input Through to Spectrum Processing:

Figure 4a. RF signals are downconverted and sampled into a continuous data stream.

l for a spectrum analyzer, then digitized. The digitized data is sent through an

Figure 4b. Samples are segmented into data records for FFT processing based on the selected resolution bandwidth.

Figure 4c. Data records are processed in the DPX transform engine

Figure 4d. Overlapping the FFTs shortens the minimum event duration required for 100% probability of intercept.

Collecting spectral data. Sampling and digitization is continuous. The digitized data stream is chopped

into data records whose length is based on the desired resolution bandwidth (RBW). An additional requirement is placed on FFT length by the desired number of points in a trace (Option 200 only). Table 1 shows this relationship and the FFT length is reported in the display if desired. Then the DPX transform engine performs a discrete Fourier transform on each record, continually producing spectral waveforms.

RF signals are downconverted and sampled into a continuous data stream.

Samples are segmented into data records for FFT processing based on the selected resolution bandwidth.

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Data records ar

e processed in the DPX transform engine.

Overlapped processing is used to improve minimum event duration performance.

Table 1: Minimum FFT length versus trace length (independent of span and RB

Trace length (points) Minimum FFT length

801 1,024

2,401 4,096

4,001 8,192

10,401 16,384

xxx

W), Option 200

As long as spectral transforms are performed faster than the acquisition data records arrive, the transforms can overlap each other in time, so no events are missed in between. Minimum event length for guaranteed capture depends on the length of the data records being transformed. An event must last through two consecutive data records in order for its amplitude to be accurately measured. Shorter events are detected and visible on screen, but may be attenuated. The DPX Spectrum RBW s

etting determines the data record length; narrow RBW ﬁlters have a longer time constant than wide RBW ﬁlters. This longer time constant requires longer FFTs, reducing the transform rate. Additional detail on minimum signal duration is provided in G

uaranteed Capture of Fast Events (see page 43).

The spectral waveforms are plotted onto a grid of counting cells called the “bitmap database”. The number held by each database cell is the z-axis count. For simplicity, the small example grid used here in Figure 6 is 11x10, so our spectral waveforms will each contain 11 points. A waveform contains one (y) amplitude value for each (x) frequency. As waveforms are plotted to the grid, the cells increment their values each time they receive a waveform point.

Figure 5. Example 3-D Bitmap Database after 1 (left) and 9 (right) updates. Note that each column contains the same total number of “hits”.

The grid on the left shows what the database cells might contain after a single spectrum is plotted into it. Blank cells contain the value zero, meaning that no p oints from a spectrum have fallen into them yet.

The grid on the right shows values that our simpliﬁed database might contain after an additional eight spectral transforms have been performed and their results stored in the cells. One of the nine spectrums happened to be computed as a time during which the signal was absent, as you can see by the string of “1” occurrence counts at the noise ﬂoor.

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General Signal Viewing > DPX Spectrum DPX Primer

Frame updates.

The maximum rate for performing the variable-length frequency transforms that produce those waveforms can be greater than 292,000 per second. Measurement settings that slow this transform rate include narrowing the RBW and increasing the number of points for the line traces available in the DPX Spectrum display along with the bitmap. Even at their slowest, spectral transforms are performed orders of magnitude faster than a physical display can respond, and also too fast for humans to see, so there’s no need to update the screen or measurements at this rate. Instead, the grid collects thousands of waveforms i

nto “frames”, each covering about 50 milliseconds (ms). A 50 ms frame contains the counts from up to 14,600 waveforms. After each frame’s waveforms have been mapped into the grid, the cell occurrence counts are converted to colors and written to the DPX bitmap, resulting in a bitmap update rate of around 20 per second.

Frame length sets the time resolution for DPX measurements. If the bitmap shows that a -10 dBm signal at 72.3 MHz was present for 10% of one frame’s duration (5 ms out of 50 ms), it isn’t possible to determine just from the DPX display whether the actual signal contained a single 5 ms pulse, one hundred 50 microsecond (μs) pulses, or something in between. For this information, you need to examine the spectra

l details of the signal or use another display with ﬁner time resolution, such as Frequency vs.

Time or Amplitude vs. Time.

Converting occurrence counts to color. About 20 times per second, the grid values a re transferred to the

next process step, in which the z-axis values are mapped to pixel colors in the visible bitmap, turning data into information (Figure 6). In this example, warmer colors (red, orange, yellow) indicate more

rrences. The color palette is user-selectable, but for now we will assume the default “temperature”

occu palette.

Number of Occurrences Color

0black

1blue

2 light blue

4 green blue

6 yellow

8 red orange

9red

Figure 6. Example Color-mapping algorithm

xxx

cyan

green

orange

The result of coloring the database cells, Figure 7, according to the number of times they were written into by the nine spectrums, one per pixel on the screen, creates the DPX displays.

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Figure 7. Color-coded low-resolution example (left) and a real DPX display (right).

In addition to the choice of palette, there are z-axis scaling adjustments for Maximum, Minimum, and Curve. Maximum sets the occurrence value that will be mapped to the highest color in the palette. Minimum sets the occurrence value for the lowest color. In the “temperature” palette, the highest color is deep red and the lowest is dark blue. Occurrence values less than the selected Minimum are represented with black pixels, while pixels that exceed the selected Maximum are red in hue but somewhat transparent. Values between Maximum and Minimum are represented by the other colors of the palette.

Adjusting the Minimum above the black default allows you to concentrate most of your color resolution over a small range of medium or higher occurrence rates to visually discriminate between different signals that have nearly equal probability values.

To see why adjustable color scaling is useful compare Figures 8 and 9. On the Scale tab, the Max control is set to 100% in Figure 8. The range of colors now covers the full z-axis range of densities from 0 to 100%. The signals used to create this bitmap are fairly diffused in both frequency and amplitude, s o most pixels have low occurrence counts or density values and the upper half of the color p alette is unused.

Figure 8. DPX spectrum bitmap with default color scale settings.

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General Signal Viewing > DPX Spectrum DPX Primer

When the Auto Co in the current bitmap, shown in Figure 9. Now none of the available colors remain unused. The e ntire palette is mapped to the occurrence values present at the time the button is selected, providing better visual resolution for low densities. Selecting the Autoscale button in the DPX display scales all three axes based on current results.

Figure 9. The Auto Color function optimizes the color scale settings.

lor button is selected, the Maximum control’s value is set to the highest pixel value

Color Mapping Curves

The mapping between z-axis values and color does not have to be linear. The Curve control lets you choose the shape of the mapping equation. A Curve setting of 1 selects the straight-line relationship. Higher Curve numbers pull the curve upwards and to the left, concentrating color resolution on lower densities. Settings less than 1 invert the curve, moving the focus of the color range towards higher density values. Figure 10 shows the mapping curves.

Figure 10. Representative color mapping curves for the “Temperature” palette.

Using the same signal shown in Figures 8 and 9, the impact of the Curve control can be observed. With the Curve control set to 1 in the Scale tab, shown in Figure 11, the mapping between color and density is

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linear, so the c colored palette illustration to the left of the Curve control in the Settings panel.

Figure 11. Over a narrow Signal Density range, the color curve is set to 1.

When the Curve control is set to 0.5, as shown in Figure 12, the best color resolution is in the upper half of the density range, and only the dark blues are assigned to densities below 50%. Note the difference in the palette illustration.

olors spread evenly across the full density range. The color distribution is visible in the

e 12. Adjusting to values less than 1, increases the contrast for viewing events in the top half of the selected

Figur density range.

In Figure 13, the Curve control is increased to 3. The majority of colors shifts to the lower half of the density scale, but various shades of orange and red are still available for densities above 50%.

Figure 13. For color curve settings greater than 1, better contrast is provided for events near the low end of the

ensity range.

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General Signal Viewing > DPX Spectrum DPX Primer

Swept DPX

DPX Spectrum is not limited in span by its real-time bandwidth. Like the regular Spectrum display, DPX Spectrum step traces and the bitmap (Option 200 only). See Figure 14.

Figure 14. Off-air ambient signals over a 1 GHz span in the swept DPX display.

The analyzer “dwells” in each frequency segment for one or more DPX frames, each containing the results of up to 14,600 spectral transforms. Dwell time is adjustable, so you can monitor each segment of the sweep for up to 100 seconds before moving to the n ext step. While dwelling in a segment, the probability of intercept for signals within that frequency band is the same as in normal, real-time spans: 100% capture of even

ts as short as 10.3 μsec.

s through multiple real-time frequency segments, building a wide-span display with line

A full pixel bitmap is created for every segment and compressed horizontally to the number of columns

d for displaying the frequency segment. Compression is done by averaging pixel densities of the

neede points being combined together. The ﬁnal swept bitmap contains a representation of the same pixel bitmap resolution, just like the non-swept bitmaps. Line traces are also created in full for each segment, and then horizontally compressed to the user-selected number of trace points for the full span.

A complex algorithm for determining the number and width of each frequency segment has been implemented. The variables in the equation include user-adjustable control settings like Span, RBW, and number of trace points, RF and IF optimization, and Acquisition BW. Installed hardware options also can affect the span segmentation. The number of segments ranges from 10 to 50 for each 1 GHz in a sweep.

A helpful piece of information for operators is the actual Acquisition Bandwidth used for capturing each segment. “Acq BW” is shown in the Acquire control panel on the Sampling Parameters tab. Acq BW is

ypically set automatically by the instrument, based on the needs of all the open displays, but can also be

t set manually. In either case, the displayed bandwidth is used for every frequency segment in the swept DPX display, though in practice, the displayed portion of the segment is somewhat narrower than the actual Acquisition BW, for performance reasons.

The entire instrument frequency range of many GHz can be covered in a DPX sweep. The Dwell Time control sets the amount of time DPX spends in each se gment. This control, circled in Figure 15, can be set between 50 ms and 100 seconds.

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Figure 15. During swept DPX operation, the Dwell time control adjusts the observation time of each frequency segment used to construct the composite DPX spectrum display.

Guaranteed Capture of Fast Events

The main reason that swept-tuned and step-tuned spectrum analyzers can’t provide 100% Probability of Intercept, POI, for a signal that isn’t continuously present is that they spend only a short period of time tuned to each segment of their frequency span during each sweep. If something happens in any part of the span other than where it is tuned at that instant, that event will not be detected or displayed. There is also a period of time between sweeps, retrace time, during which the analyzer is not paying attention to the i the time between acquisitions. Their POI depends on a combination of factors including span, number of FFT points, acquisition time, memory read/write time, and signal processing speed. Vector analyzers process information sequentially, so when read/write from data and processing is occurring, data is not being acquired.

nput signal. FFT-based analyzers, including vector signal analyzers, also miss signals during

RSAs, on the other hand, capture data across all frequencies within their real-time span during every acquisition. With Tektronix’ exclusive Frequency Mask trigger and DPX Density trigger, POI increases to 100%, insuring capture of any spectral event matching the trigger deﬁnition. When operating in free run as

mple spectrum analyzer, the RSA has a POI similar to other FFT-based analyzers, with gaps between

asi each acquisition. Processing is done concurrent with the acquisitions.

Guaranteed Capture in DPX Real-Time Spans

The DPX Spectrum display captures any signal that is at least 10.3 microseconds long (for instruments with Option 200) and within the real-time bandwidth. This performance is possible because the RSA computes up to 292,000 spectrum transforms per second. The faster the spectrum updates, the s horter the time between acquisitions and the greater the probability that any signal will be detected.

Table 1 shows the speciﬁed minimum signal duration (MSD) for 100% probability o f intercept under various combinations of Span and RBW in DPX for a representative RSA model. As you can see, MSD is affected by multiple factors.

Table 2: Minimum signal duration speciﬁcations for RSA6100A series spectrum analyzers

Span

(MHz)

110 1000 110 1024 292,969 10.3

110 300 367 2048 146,484 20.5

RBW (kHz)

Span/RBW

Ratio

FFT

Length Spectrum/sec

MSD for

100% POI (μs)

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Table 2: Minimum signal duration speciﬁcations for RSA6100A series spectrum analyzers1(cont.)

Span

(MHz)

110 100 1100 4096 73,242 41.0

110 30 3667 16384 18,311 163.9

110 20 5500 32768 9,155 327.7

xxx

With Options 110 and 200 under various combinations of control parameters.

RBW

(kHz)

Span/RBW

Ratio

FFT

Length Spectrum/sec

MSD for

100% POI (μs)

To demonstrate the POI in action, a challenging bi-stable signal is used. A CW sinusoid sits at 2.4453 GHz most of the time, but every 1.28 seconds, its frequency changes for about 100 μs before returning to normal.

The duty factor of this transient is less than 0.01%.

Figure 16 shows a swept analyzer set up for a 5-second sweep of its MaxHold trace. It shows that there is somethi

ng occurring around the signal. This sweep rate was empirically determined to be the optimum rate for reliable capture of this signal in the shortest time. Faster sweep times can reduce the probability of intercept and result in fewer intersections of the sweep with the signal transient.

igure 16. Swept spectrum display of the infrequent transient.

he DPX display shown in Figure 17 shows the exact same event, also captured over a 5 second period. A

T lot more information can be discovered about the transient. It is obvious at ﬁrst glance that the signal is hopping by about 3 MHz, with 1.2 MHz of frequency overshoot on transitions

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Figure 17. The DPX spectrum display after 5 seconds. The MaxHold trace is cyan.

Guarante

Probability of intercept (POI) for s ignals within a single segment, while DPX is dwelling in that segment, is the sa But just as in traditional swept analyzers, during the time the acquisition is tuned to any one segment, the analyzer is not monitoring signals in any of the other segments, so probability of capture in segments other than the current one is zero. Because of the wide real-time bandwidth, the number of segments needed to cover the span is much less than for swept analyzers, so the overall probability of intercept is signiﬁcantly better for DPX sweeps.

Another factor affecting POI is number of trace points. The bitmap is always 801 points wide, but the line traces allow user selection for number of points. 801 is the default and the other choices are 2401, 4001 lower waveform update rate increases the minimum signal duration proportionally. This caution applies for swept and non-swept operation. The trace length control is on the Prefs tab in the DPX control panel.

ed Capture in DPX Swept Spans

me as for non-swept DPX operation (POI = 100% for events as brief as 10.3 microseconds).

, and 10401. Frequency transforms for traces containing more than 801 points take longer, and this

DPX Density Measurements

“Density” is a measure of the amount of time during a deﬁned measurement period during which signals are present within a particular area of the DPX Spectrum bitmap. A clean CW tone gives a 100% reading, while a pulse that is on for one microsecond out of every millisecond reads 0.1%. This section describes

ow density is computed from hit counts.

If we plot 41 more waveforms into the example grid we used previously in Figure 6 (in addition to the nine we already plotted), each column ends with a total of 50 hits (Figure 18). The density for any one cell in a column is its own count value divided by 50, expressed in percent as shown in Figure 19. The math is very simple: a cell with 24 counts has a 48% density. In practice, instead of batches of 50 waveforms, we collect a frame of thousands of waveforms before each update to the density bitmap.

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General Signal Viewing > DPX Spectrum DPX Primer

Figure 18. Grid showing cell counts after 50 waveforms. For each column, the sum of z-axis values is 50.

Figure 19. Grid after converting occurrence counts to percent density values. The sums of the cell density measurements within each column are all 100%.

suring Density with Markers

Mea

Hit counts are cleared after every frame update, as long as Persistence is not turned on. The density

lue for any pixel is simply the percent of time it was occupied during the most recent 50 ms frame.

va Markers can be used to see the Density value for one or more individual points on the screen, enabling measurements of the signal density at any interesting point in the DPX Spectrum display.

In Figure 20, Wireless LAN signals are analyzed in the presence of a Bluetooth radio signal in the 2.4 GHz ISM band.

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Figure 20. DPX spectrum display of WLAN and Bluetooth signals, with a marker on the highest signal.

The “Marker to Peak” function was used to ﬁnd the peak signal recorded in the display. The m arker readout i

n the upper left corner of Figure 20 shows the Density, Amplitude, and Frequency for the pixel you selected with the marker. By adding additional markers, you can measure the signal density differences between multiple signals of interest.

Marker Peak Search in the DPX Bitmap

Markers on the DPX bitmap can search for peaks, similar to marker peak searching on spectrum line traces. For a human, it is pretty easy to discern “signals” in the bitmap picture. Your brain intuitively identiﬁes strings of contiguous bright p ixels. This isn’t so easy for a computer. The ﬁrst thing the RSA

o for any peak search is analyze pixel density values to identify apparent signals. Then it can sift

must d through these density peaks for the amplitude peaks you want to ﬁnd.

is density values for the pixels in each column of th e bitmap are internally converted into histograms

Z-ax to ﬁnd density peaks indicating the presence of signals. Table 2 shows the ﬁve middle columns from the example grid we used to illustrate density measurements in a previous section (Figure 19). The density values for each pixel in the middle, highlighted column are plotted on the y axis in the bar chart in Figure 21. The bar chart x axis is bitmap row number, numbering from the top of the table.

Table 3: Bitmap section showing density values.

0% 0% 0% 0% 0%

0% 0% 8% 0% 0%

0% 0% 12% 0% 0%

0% 0% 26% 0% 0%

0% 0% 36% 0% 0%

0% 2% 6% 2% 0%

4% 8% 0% 8% 0%

86% 82% 4% 76% 12%

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General Signal Viewing > DPX Spectrum DPX Primer

Table 3: Bitmap section showing density values. (cont.)

10% 8% 6% 14% 86%

0% 0% 2% 0% 2%

xxx

Figure 21. Bar chart of the density values in the bolded column of Table 2.

Assume that Density Threshold is set to 5% and Density Excursion to 5% also. Starting w ith x=1 in the bar chart, test each bar against the threshold. The threshold criteria is met at x=2. Keep testing until you

a bar that is shorter than the previous bar by a t least the Excursion setting. In this case it is x=6. This

ﬁnd tells us that a “signal” covers rows 2 through 5. Its density peak is at row 5.

you can look for another peak. Continue looking at bars to the right and you will ﬁnd a density

Now value at row 9 that meets the threshold criteria, but since there are no bars to the right of it that meet the excursion criteria, we can’t declare row 9 a signal b ecause it fails to meet the excursion criteria. If row 1 had1%density,thenrow9wouldbeadensitypeak.

Once density peaks are found for all columns in the bitmap, we can start looking for the amplitude peaks. When the Peak button is selected, the analyzer checks the histograms of every column in the bitmap and ﬁnds the density peak with the highest amplitude. The amplitude search has its own versions of Threshold and Excursion settings, but in dBm and dB units. When Next Peak Down command is given, the search will scan inside the current column for the next density peak. Next Peak Right examines each column to the right of the current marker location to locate density peaks that also meet the amplitude peak criteria.

To demonstrate the value of marker peak search in the DPX bitmap, we will use the time-multiplexed signals showing multiple amplitude levels from an example earlier in this manual. The Peak button and its menu equivalent place the active marker on the peak signal in Figure 22. The peak signal is the density peak of highest a mplitude in the bitmap.

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Figure 22. The marker was positioned by selecting the Peak button. Density, frequency, and amplitude measurements at the marker are displayed in the upper left corner of the graph.

The Marker Toolbar, at the bottom of Figure 22, allows easy navigation of peak signals (Peak Left, Peak Right, Next Peak Up,orNext Peak Down). Selecting the arrow keys enables the marker to search for

amplitude/density peaks at other frequencies, while the Next Peak Up and Next Peak Down arrows enable the marker to search for other high-density points at the same frequency.

In the Deﬁne Peaks tab of the D eﬁne Markers control panel, Figure 24, you can adjust the density threshold and excursion controls to modify search behavior. The amplitude threshold and excursion controls also apply to DPX marker searches. Smoothing keeps the marker from ﬁnding multiple peaks within the same apparent signal by averaging an adjustable number of pixel densities together, bu single-pixel measurement readout displayed by the marker.

t it does not affect the

Figure 24. Amplitude and Signal Density controls can be adjusted to deﬁne Peak search behavior.

Density Measurements over an Adjustable Area (“The Box”)

The density for a single pixel is its ratio of actual hits vs. possible hits over a deﬁned time period, and markers display these density values. For measuring density over an area larger than one pixel, Option 200 includes a measurement box you can resize and drag around in the DPX Spectrum display with your mouse or ﬁnger.

If you could make the box so narrow that it contained only points within a single column of pixels, the density of this area would be the sum of the included pixels’ density values. For example, if the box was three pixels tall and the density values for these pixels were 4, 2, and 7% respectively, the overall density for the three-pixel area would be 13%. Imagine a box one pixel wide and as tall as the graph. Assume that the input signal’s amplitude was such that all hits fell at or near the vertical center of the screen. Since 100% of the waveforms written to the bitmap passed through the box, the density for the box is 100%.

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General Signal Viewing > DPX Spectrum DPX Primer

When you widen t the included pixels in each column inside the box. The aggregate density value for this box is the average density, calculated by adding the column density sums then dividing by the number of columns. For a 100% result, there must not be any hits above the top edge of the box or below its bottom edge. In other words, every waveform drawn across the graph entered the box through its left side and exited the box through its right side, with no excursions out the top or bottom. Figure 24 demonstrates this principle on a CW signal. As you can se is 100%. On the right hand side, there are signals below the box, therefore the density is less than 100%.

he box to cover a broader range of frequencies, software computes the density sum for

e on the left-hand side, no amplitudes exist above or below the box; the density of the signal

Figure 24. Density of signals deﬁned w ithin an area. Left: Correct measurement of a CW signal. All columns in the box include the signal. Right: Incorrect measurement area. The measurement is accurate, but probably not what you expected. Some columns in the box contain no hits, so they contribute zeros to the calculation of average density.

The density measurement box’ vertical size and location are always set in dB and dBm, no matter what units you have selected for measurements. (Amplitude control panel > Units tab) The box is not draggable when the selected units are linear (such as Amps, Volts, Watts…), though you can still adjust its size and location using the Frequency and Amplitude controls in both the D PX Settings > Density and Trigger > Event tabs. Since the vertical scale is non-linear, a box of constant amplitude changes visual height as it changes vertical position, a disconcerting effect if you are trying to drag it.

Figure 25. DPX Density control panel is used to deﬁne the area of interest for DPX density measurements.

A readout will appear somewhere in the graph. If the box is off-screen, the readout will be accompanied by an arrow pointing towards the invisible box. Grab this readout with your mouse or ﬁnger and drag the density readout to the area you want to measure.

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General Signal Viewing > DPX Spectrum DPX Primer

To adjust the bo settings, use the knob, arrow keys, or keyboard to adjust frequency and amplitude values for the rectangle. These controls are located in the right half of the Density tab in the control panel.

x size, a mouse is the easiest way to drag the sides and corners of the rectangle. For precise

Persistence

Previous sections of this topic have assumed that persistence was not applied to the DPX bitmap. Without persistence, hit counts in the grid are cleared after eac h frame update. Now we will describe how persistence modiﬁes this behavior, starting with inﬁnite persistence because it is simpler than variable persisten

Hit counts are not c leared between frames if inﬁnite persistence is enabled. When the instrument is set up for con above the DPX display. Software keeps track of the total number of waveforms computed during the entire collection period. Density equals the total number of hits to a cell divided by the total number of waveforms.

Variable persistence is trickier. A single-occurrence signal shown in the bitmap does not disappear suddenly upon the next frame update, nor does it linger forever. It fades gradually away. The user sets a time constant for the Dot Persistence control which determines how long it takes for signals to fade. Fading is accomplished by reducing the hit count in every cell, after each frame update, by a factor based on the

ce.

tinuous acquisitions, hits keep collecting until you stop acquisitions or click the Clear button

persistence time constant. The longer the time constant, the less the hit counts are reduced.

Figure 26. Example of fast transient discovery with and without variable persistence turned on. In the display on the left, with variable persistence of 10 seconds, the occasional sub-second transient that spikes up above the normal signals is held in the display rather than disappearing as soon as the signal goes away. The display on the right, with persistence turned off, requires watching the display continually to see the brief signal.

Not only are single-occurrence signals allowed to remain in the display for awhile by variable persistence, additional hits keep piling on. The result is that cell values are no longer pure hit counts; they include counts due to new hits from waveforms plus proportionally reduced counts from prior frames. As part of translating hit counts into density values, a new software algorithm uses a ﬁnite-series equation to discriminate between the effects of persistence and the arrival of new hits. The inﬂationary effects of

RSA6100A Series Real-Time Spectrum Analyzers Help 51

General Signal Viewing > DPX Spectrum DPX Primer

persistence on

cell counts are removed, so density readings represent the true ratio of actual hits to possible

hits over the persistence interval.

The density co

mputation for variable persistence is a very good estimate of true signal density, with errors

of less than 0.01%. For exact density measurements, use either no persistence or inﬁnite persistence.

Another sub

tlety of persistence is its smoothing effect on the density measurement of intermittent signals.

Consider a pulse that is on for 10 ms and off for 90 ms of each 100-ms cycle. We’ll make the simplifying assumption that the pulse ON time a lways falls entirely within a single DPX frame update (50 ms). If persistence is not applied, the density measurement is computed on each individual frame. The results will be 20% for each frame containing the ON time and 0% for the other frames. If inﬁnite persistence is enabled, however, the density measurement will settle to 10% after the second frame, and remain at this valu

e for as long as the pulsing continues. With persistence, the density is effectively computed

over many frames.

Persistence Effects on Density

Persistence does not alter colors in a density-based bitmap. Its effect is to extend the amount of time over which densities are calculated, leaving signal events visible for the persistence duration.

Before the introduction of density measurements and extra-long hit counters, persistence caused colors to “bloom”, becoming more and more intense over time as the hit counts increased. Longer persistence intervals caused increased blooming, turning crisp signals into fat red stripes. When hit counts are converted to density values (requires Option 200), the display is not subject to this effect. As long as the

t signals maintain reasonably stable repetition rates and duty ratios, their density values will also

inpu remain stable despite ever-increasing hit counts in the underlying grid cells.

ou are accustomed to the original hit-count-based persistence displays, it may seem counterintuitive

If y that repeating signals in a density-based bitmap will not get brighter and redder over time with inﬁnite persistence. A quick review of the density algorithm explains why: the hit count is divided by the total number of waveforms over the persistence interval. For example, if a signal occupies a pixel 50% of the time over a period of 15 minutes, the density reading will be 50% throughout the entire 15 minutes, though the underlying hit count is steadily increasing.

Z-Axis Resolution

Another factor that can cause color bloom is overﬂow of the hit counters. If a pixel could only count up to 1000 hits, its density and color values would clip at 100% after just 1000 hits, even if waveform points continue to arrive in the same pixel location. With waveform points being written to the bitmap at rates approaching 300k/sec, counts add up really fast for highly-repetitive signals. Deeper counters permit higher hit counts, so overﬂow happens much later, as shown in Table 3.

Table 4: Comparison of DPX z-axis resolution and its effect on saturation.

RSA6100A Series Standard RSA6100A Series Option 200

Hit Count

16-bit integer

36-bit custom ﬂoat (equivalent to 33-bit integer)

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General Signal Viewing > DPX Spectrum DPX Primer

Table 4: Comparison of DPX z-axis resolution and its effect on saturation. (cont.)

RSA6100A Series Standard RSA6100A Series Option 200

Maximum Hit Count

Minimum Time until Overﬂow (for pixels with 100% density)

xxx

<50 msec 8.1 hours

Clipping due to overﬂow of the counters in one or more cells will not occur until hours have passed, or even days.

One more beneﬁt to having deeper hit counters is better visual resolution of density. RSAs with the highest-performance DPX hardware installed use ﬂoating-point numbers to count hits, allowing us to count billions of waveforms while retaining one-hit resolution, providing better than 99 dB of dynamic range for dens

ity measurements. Density measurements in μ%, n%, and even f% ranges are quite possible for

extremely rare signals captured with inﬁnite persistence.

With st

raight-line mapping between density and color (Curve setting of 1), resolution is ﬁxed by the number of colors in the palette. For non-linear mappings (Curve settings higher or lower than 1), most of the colors are concentrated at either the low or high end of the density scale, so you can visually discriminate ﬁner differences between d ensity values in that range.

Persistence Adjustments

Dot Persistence can be enabled for the “Bitmap” trace using the Settings control panel. The Persistence can be displayed as Inﬁnite or Variable. For Variable Persistence, you can select the time constant for

ing in seconds as shown in Figure 27.

fad

Figure 27. The trace settings control panel allows user control of persistence parameters.

Figure 28 demonstrates the observed behavior of variable persistence when a CW signal, represented in the ﬁrst frame, is turned off. Even if the event was instantaneous and was conﬁned within a single frame, you will observe the color changing to indicate lower and lower density va lues, until the signal ﬁnally disappears entirely.

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General Signal Viewing > DPX Spectrum DPX Primer

Figure 28. Wi period of time before fading away.

th variable persistence, a brief CW signal captured by DPX remains in the display for an adjustable

DPX Density Trigger

The standard DPX display shows you a clear picture of transients and other hard-to-ﬁnd signals. The version of DPX in the RSA6100A Option 200 goes well beyond helping you discover these difﬁcult to ﬁnd signals by actually triggering on their appearance to capture them into acquisition memory for in-depth analysi

Other t rigger methods can detect signals that exceed an amplitude threshold, or even a sophisticated amplit higher amplitude is sometimes present at that same frequency. The Runt trigger addresses some of these signal-under-signal cases, but not all. As shown in Figure 29, the DPX Density trigger can discriminate signals within a precise amplitude-frequency range without the operator having to know any characteristics of the target signal besides where it might show up in the DPX Spectrum graph.

s. If you can see it in the DPX bitmap, you can trigger on it.

ude-vs-frequency mask, but they can’t ﬁnd a signal at a particular frequency if another signal of

Figure 29. Example of Density Trigger. Left: A free-run DPX spectrum display showing pulses with varying frequency. Occasionally, a short pulse in the middle appears for a split instant, but it is hard to capture it with just a Run/Stop button. Right: The triggered DPX displays shows the low-amplitude pulse that was not apparent in the untriggered display. The analyzer was set to trigger whenever the average density in the user-drawn box measured 50% or higher.

The DPX Density trigger uses the same screen-based measurement box as the DPX Density measurement. While the target signal is absent, the density measurement characterizes the “normal” signals within the box. When the target signal ﬁnally appears, the density value increases. The trigger system monitors the density measurement and activates a trigger whenever the density value exceeds the adjustable density threshold. The only thinking you have to do is to set this threshold to a level somewhere between the normal density readings and the density due to the trouble-making signal. However, the instrument software can compute the threshold value automatically.

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General Signal Viewing > DPX Spectrum DPX Primer

Trigger On This

The Trigger On This™ function allows you to point and click to set up the DPX Density trigger. By right-clicki RSA6100A Series touchscreen display for about a second, a menu selection will appear. Selecting Trigger On This causes a DPX Density box to appear and automatically adjusts the threshold. The DPX Spectrum display will now only update whenever the automatic threshold is exceeded. Subsequently, if needed for your signal, open the Trigger control panel to adjust the density threshold or the size of the measurement box until the event is reliably captured.

™

ng on a spot within the DPX Spectrum display, or pressing and holding your ﬁnger on the

Automatic Threshold Adjustment by Trigger On This™

The trigg signal was present at the moment you selected Trigger On This, the threshold will be 20% less than the signal density, so the next time the signal is present long enough (or present enough times) to exceed the threshold density, it will cause a trigger. If the signal happened to be missing when you selected Trigger On This, the threshold value will be even lower. If you clicked in a part of the display with no signal activity at all, the threshold will be set to zero. Any signal that shows up here will ﬁre the trigger, as show

er density threshold automatically set by Trigger On This is 80% of the measured value. If the

ninFigure32.

Figure 30. The analyzer triggered when the density in the DPX measurement box exceeded the threshold set by Trigger On This. You can see in the Spectrogram and Frequency-vs-Time displays that the signal event which caused

RSA6100A Series Real-Time Spectrum Analyzers Help 55

General Signal Viewing > DPX Spectrum DPX Primer

the trigger was power level trigger would not have worked.

a quick frequency hop. The Time Overview shows that the signal amplitude never changed, so a

DPX Density Trigger Timing

The time resolution for DPX density measurements is the frame length, around 50 ms. A basic implementation of the DPX Density trigger concept is also frame-based, so a trigger event that occurs anywhere within a frame will not be recognized until the end of the frame. Therefore, the worst case trigger un

DPX Density trigger doesn’t always have to wait until the end of a frame before ﬁring. For the common co measurement in the trigger can be computed many times within each frame and it can ﬁre the trigger as soon as the threshold is exceeded.

Consider the case where the threshold is zero. As soon as a single waveform causes a hit within the measurement box, we know that the density is greater than zero. It takes a little longer to test for a 5 or 10% density, and even more time for thresholds at or near 100%.

The DPX Density trigger can also be set to ﬁre when the measured density is below the threshold v alue. This is useful when you suspect that your signal is missing some of the time. For a signal that is supposed to be CW, you can set the trigger controls to acquire when the density measurement of the signal peak drops below 100%. When using the “lower than” form of the DPX Density trigger, the time resolution is one f least 85% of the full test time has elapsed. In order to keep things simple and fast in the trigger module, the RSA just waits until the end of each 50 ms frame to do the “lower than” comparisons.

certainty is 50 ms.

nﬁguration of triggering when the measured density is higher than the threshold, the density

rame because of the following logic: We can’t be sure the actual density is less than, say, 15% until at

Persistence and DPX Density Trigger

The smoothing effect of persistence on density measurements can h elp in determining a good threshold value. With persistence turned off, an infrequent signal’s density reading jumps between higher and lower values as it turns on and off, and it can be hard to read these ﬂashing numbers. By turning persistence

n, you instruct the instrument to average the density over a longer time period. This density result is

o somewhere between the ON and OFF density values - the very deﬁnition of a good trigger threshold.

Unlike the DPX Density measurement, the DPX Density trigger is not affected in any way by persistence. Density calculations in the trigger system are made with hit count data received from each individual DPX frame, before any persistence is applied. Even when the density measurement reading in the display is averaged over many frames due to persistence, the trigger is computing density for each frame and comparing these quick snapshots against the threshold setting.

56 RSA6100A Series Real-Time Spectrum Analyzers Help

General Signal Viewing > DPX Spectrum DPX Spectrum Overview

DPX Spectrum O

The DPX Spectr that cannot be seen on a swept spectrum analyzer. A DPX Spectrum indicates how traces change in two ways. First, it uses color shading to show how consistent the shape of a trace is. Second, it u ses persistence to hold signals on the screen so you can see them longer.

verview

um display enables you to see how traces change over time and thus displays signal e vents

DPX Spectrum Display

The DPX Spectrum display works by using a two-dimensional array to represent points on the display. Each time to each point in the display based on the value of its counter. Thus, as acquisitions occur over time, a colored waveform, the Bitmap, develops on the display that shows how frequently a display point has been written to.

An important feature of the DPX Spectrum display is persistence. Persistence sets how long a point on the display will be visible. You can set the Display Persistence to be Variable or Inﬁnite. In variable persistence mode, you specify a decay period that limits how long a point will be displayed. In inﬁnite persistence mode, once a point in the display has been written to, it will remain visible indeﬁnitely.

To display the DPX Spectrum view:

a trace writes to a point on the display, a counter in the array is incremented. A color is assigned

1. Select Freq and use the front panel knob or number keys to set the measurement frequency.

2. Select the Displays button or Setup > Displays. This displays the Select Displays dialog box.

3. From the Folders box, select General Signal Viewing.

4. Sel

5. Click the Add button. This will add the DPX Spectrum icon to the Selected Displays box (and remove

6. Click the OK button. This displays the DPX Spectrum view.

ect DPX Spectrum from the Available displays box.

from the Available displays box).

RSA6100A Series Real-Time Spectrum Analyzers Help 57

General Signal Viewing > DPX Spectrum DPX Spectrum Display

Available Traces for Display — Standard Instrument

Five traces can be shown in the DPX Spectrum display—one bitmap and four line traces. The default traces are Bitmap and +Peak detection. The other three traces are –Peak detection, average detection, and math.

Trace Description

Bitmap

+Peak detected Line trace. Displays the maximum amplitude values acquired in each update. Normal and

–Peak detected Line trace. Displays the minimum amplitude values acquired in each update. Normal and

Average detected

Math Trace

xxx

Displays the density of acquired data. The number of data points acquired at each pixel (representing a particular amplitude level at a speciﬁc frequency is indicated by color).

Hold functions are available for this trace.

Line trace. Displays the average of all the values acquired in each update. Normal and Hold functions are available for this trace.

Line trace. Displays the difference between two traces. The two traces used are set in the Traces tab of the Settings panel.

Determining Which Trace Types Are Displayed

You can see the status of all the traces by selecting the Trace drop-down list. Traces that are not displayed are preceded by "Enable". In the following ﬁgure, you can tell that the Bitmap and -Peak Trace traces are displayed but the +Peak, Average, and Math Traces are not displayed.

Selecting Enable -Peak Trace from the Trace list displays the -Peak detected values trace.

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General Signal Viewing > DPX Spectrum DPX Spectrum Display

You can see whether a trace is enabled by looking at its Show check box. The "selected trace" is selected in the Trace list. The Show check box is checked when the selected trace is enabled. To the right of the show box ar Normal,...). You can enable/disable the selected trace by checking or unchecking Show.

e readouts for detection of the selected trace (+Pk, Avg (VRMS), ...) and its function (Hold,

Selecting Traces for Display — Standard Instrument

To select a trace for display:

1. Use the Settings control panel:

lect Setup > Settings or click the Settings button.

Select the Trac es tab.

Select the trace from the drop-down menu.

Select the Show check box.

2. Select a trace from the Trace drop-down list.

Specifying How +Peak, –Peak, and Average Traces Are Display ed

You control how the +Peak, –Peak and Average (Avg (VRMS)) traces are displayed from the Traces tab of the Settings control panel. From the Traces tab, you can also specify whether these traces display results from single updates or results collected over multiple updates.

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General Signal Viewing > DPX Spectrum DPX Spectrum Display

To change how th

1. Select Setup > Settings or click the Settings button.

2. Select the Traces tab.

3. Select the trace type from the drop-down list.

4. If you select +Peak Trace or -Peak Trace, use the Function drop-down list to select either Normal or Hold.

a. Select Normal to set the trace to display the maximum/minimum values acquired in each

individual update.

b. Select Hold to set the trace to display the maximum/minimum values acquired over time. The

trace val ues are updated only if they exceed the existing values.

5. If you select Avg (VRMS), use the Function drop-down list to select either Normal or Average .

a. Select Normal to set the trace to display the average values acquired in each update.

b. Select

enter the number of times the trace is averaged.

e traces are displayed:

Average to set the trace to display an average of the average values. Use the Count box to

Available Traces for Display — Option 200 Instrument

Five traces can be shown in the DPX S pectrum display—one bitmap and four line traces. The default traces are Bitmap and Trace 1. The other three traces are 2, 3, and math. Line traces 1, 2, and 3 have user-selectable Detection and Function settings. The ﬁnal line trace is Math, allowing you to subtract one line trace from another.

Selecting Traces for Display — Option 200

is is done almost the same as with the standard instrument, except that the choices available for Trace

Th are different. Instead of +Pk, –Pk, and Avg traces, you can select Trace 1, 2 , and 3. Additionally, you can set the Detection method for each of these traces to +Pk, -Pk, or Avg (VRMS).

Reference. C

hanging the DPX Spectrum Display Settings (see page 61)

60 RSA6100A Series Real-Time Spectrum Analyzers Help

General Signal Viewing > DPX Spectrum DPX Spectrum Settings

DPX Spectrum S

Menu Bar: Setu

Front Panel / Application Toolbar: Settings

The measurement settings for the DPX Spectrum display are shown in the following table.

Settings tab

Freq & Span (see page 98) Sets frequency and span parameters for the DPX Spectrum display.

W (see page 1 03) Sets Resolution Bandwidth.

Traces (Bitmap) Tab (see page 61)

see page 63)

Traces (

Traces ( page 103)

Scale (see page 67) Sets the vertical and horizontal scale parameters.

Prefs (see page 106) Speciﬁes whether certain display elements are visible.

Density (see pag e 68) Speciﬁes location and size for DPX Density triggering measurement box.

Audio Demod (see page 69) Enables and sets parameters for audio demodulation function.

xxx

Math) Tab (see

ettings

p > Settings

Description

Allows you to conﬁgure the Bitmap Trace.

Allows y

ou to select the number and types of traces to display and their functions.

ou to conﬁgure the Match Trace.

Traces Tab – Bitmap

The Traces Tab allows you to set the display cha racteristics of displayed traces in the DPX Spectrum display. The Traces tab for the DPX Spectrum display has two versions: one for the DPX Bitmap trace (described in this topic) and one f

Option 200 traces tab (Bitmap trace)

or line traces (see page 63).

RSA6100A Series Real-Time Spectrum Analyzers Help 61

General Signal Viewing > DPX Spectrum Traces Tab – Bitmap

Traces tab sett

Setting

Trace drop-do

Show Speciﬁes whether or not the selected trace is displayed.

Intensity (standard instrument only)

Dot Persis

Variable The Variable dot persistence setting controls how long a point in the display is visible

Inﬁnite The Inﬁnite dot persistence setting prevents a point in the display from fading.

Freeze Halts up

ace As...

Save Tr

Show Re

xxx

called Trace

ings for the bitmap trace (Standard and Option 200)

Description

wn list

tence

Select Bitmap to set the parameters of the DPX Spectrum Bitmap trace.

Use Intensity to control the visibility of events. An increased intensity l evel allows a single, short event to be seen. This also makes such an event subject to the persistence controls. T events. Range is 1-100%. Resolution: 1.

Allows a dot to remain visible if it is not updated with new data. Choices for this setting are Variable and Inﬁnite.

before fading. This setting has no units associated with it.

Standard

Option 200 instrument Range: 50 ms–100 s.

Saves t

Displa

his allows you to see the effect of the Persistence controls on infrequent

instrument Range: 1–1000. Resolution 0.1.

dates to the selected trace.

he selected trace to a ﬁle for later recall and analysis.

ys a saved trace instead of a live trace.

Dot Persistence

Dot Persistence is the characteristic of the DPX Spectrum display that determines how long a pixel in the display remains visible.

To set the Persistence:

1. Select Setup > Settings.

2. Select the Traces tab.

3. Select Dot Persistence.

lect either Inﬁnite or Va riab l e.

4. Se

5. If you select Variable, enter a value in the text box. The Variable persistence value can be set from 1 to

000 in the base instrument, and from 0.05 to 100 seconds with Option 200.

Saving Traces

To save a trace for later analysis:

1. Select the Save Trace As button. This displays the Save As dialog box.

62 RSA6100A Series Real-Time Spectrum Analyzers Help

General Signal Viewing > DPX Spectrum Traces Tab

2. Type a name for the saved trace and click Save.

Show Recalled Trace

You can recall a previously saved trace for comparison to a live trace. First, specify a trace for recall and second, enable Show Recalled Trace.

To select a trace for recall:

1. Select the ... button to display the Open dialog box.

2. In the Open dialog, navigate to the location of the saved trace.

3. Select the desired trace ﬁle.

4. Select OK to complete your selection.

5. Select the Show recalled trace check box.

6. Verify that the trace’s Show check box is selected (either on this tab or next to the drop-do

located at the top-left corner of the graph).

wn list

Traces Tab

The Traces Tab allows you to set the display cha racteristics of displayed traces in the DPX Spectrum display. The Traces tab for the DPX Spectrum display has two versions. One for non-Bitmap traces (described in this topic) and one for t

RSA6100A Series Real-Time Spectrum Analyzers Help 63

he DPX Bitmap trace (see page 61).

General Signal Viewing > DPX Spectrum Traces Tab

Option 200 Traces tab

Setting

Trace drop-down list

Show Speciﬁes whether or not the trace shown in the Trace setting is displayed.

Freeze Halts upd

on (Option 200 only)

Detecti

Function

Save Trace As... Saves the selected trace to a ﬁle for later recall and analysis.

Show Recalled Trace Displays a saved trace instead of a live trace.

Count Enables user adjustable number of averages . This setting is only present when Function

xxx

Description

Selects which trace to conﬁgure. For standard instruments, the available traces are Bitmap, +P 200, the available traces are Bitmap, Trace 1, Trace 2, Trace 3, and Math.

Sets the detection methods are +Peak, -Peak, and Avg (VRMS) Not all detection methods are available in all displays.

Selects the trace processing method. Available settings are: Normal, Average, and Hold.

=Ave

eak detected, -Peak detected, Average, and Math. In instruments with Option

ates to the selected trace.

Detection method used for the trace. Not available for saved traces. Available

rage.

Detection

Trace Detection occurs when the trace is being decimated by the measurement. For example, if the maximum number of trace points is 100,000, and the selected analysis region is 200,000 samples, the

asurement must decimate the 200,000 resulting trace points by 2 to prevent exceeding the 100,000 trace

me point limit. Since only one value can be selected for each trace point, an algorithm must be used to select (detect) the appropriate value to use.

The available detection methods are:

Peak – Each point on the trace is the result of detecting the positive peak value present in the set of

IQ samples available to that trace point.

-Peak – Each point on the trace is the result of detecting the negative peak value present in the set of IQ samples available to that trace point.

Avg (VRMS) [Average V

] – Each point on the trace is the result of determining the RMS Voltage

RMS

value for all of the IQ samples available to the trace point. When displayed in either linear (Volts, Watts) or Log (dB, dBm), the correct RMS value results. When the averaging function is applied to a trace, the averaging is performed on the linear (Voltage) values, resulting in the correct average for RMS values.

64 RSA6100A Series Real-Time Spectrum Analyzers Help

General Signal Viewing > DPX Spectrum Traces Tab

DPX Trace Proce

The +Peak, -Peak, and Average traces can be processed to display in different ways. The Function setting controls trac

Hold - Displays the value in the trace record for each display point. Each new trace display point is compared to comparisons. Available for traces using +Peak or -Peak detection.

Normal -Dis for all detection selections.

Average -D displayed trace. There is one vertical value for each underlying frequency data point. Once the speciﬁed number of traces have been acquired and averaged to generate the displayed trace, each new trace takes the place of the oldest trace in the calculation. The Count setting speciﬁes how many traces are averaged. Available for traces using Average detection.

Trace averaging uses the exponential method. If Count = 10, the newest trace’s contribution to the averaged trace is 10%. When Count is not checked, the algorithm assumes the maximum number of traces contributing to the average is

ssing

e processing.

the previous maximum value and the greater value is retained for display and subsequent

plays the trace record for each display point without additional processing. Available

efault setting for the Average. Multiple traces are averaged together to generate the

Saving Traces

ve a trace for later analysis:

To sa

1. Select the Save Trace As button. This displays the Save As dialog box.

2. Type a name for the saved trace and click Save.

Recalling Traces

You can recall a previously saved trace for comparison to a live trace. First, specify a trace for recall and second, enable Show Recalled Trace.

RSA6100A Series Real-Time Spectrum Analyzers Help 65

General Signal Viewing > DPX Spectrum Traces Tab

To selec t a trac

1. Click the ... button to display the Open dialog box.

2. Navigate to the desired ﬁle and click Open.

3. Check the Show Recalled Trace check box.

4. Verify tha

located at the top-left corner of the graph).

e for recall:

t the trace’s Show check box is selected (either on this tab or next to the drop-down list

66 RSA6100A Series Real-Time Spectrum Analyzers Help

General Signal Viewing > DPX Spectrum Scale Tab

Scale Tab

The Scale tab a

llows you to change the vertical scale settings and set the color scheme used for the Bitmap trace. Changing the scale settings changes how the trace appears on the display but does not change control settings such as Measurement Frequency.

Setting

Vertical

Scale Changes the vertical s cale.

Offset Adjusts the Reference Level away from the top of the trace display.

Reset Scale Sets Scale to its default value and Offset to zero. Disabled when Units (Setup > Analysis

Autoscale

Horizontal

Scale Changes the horizontal scale.

Position

Autoscale

DPX Bitmap

Color Allows you to select the color palette used for the Bitmap trace.

Max

Min

Curve Adjusts how colors are mapped to the signal density. The mapping can be linear (Curve

Auto Color Adjusts the Max and Min settings to display the broadest range of colors.

xxx

Description

Controls the vertical position and scale of the trace display.

> Units) is set to Watts or Volts.

Resets the scale of the vertical axis to contain the complete trace. Disabled when Units (Setup > Analysis > Units) i s set to Watts or Volts.

Controls the horizontal position and scale of the trace display.

Adjusts the horizontal position of the signal. This does not change the center frequency.

Resets the scale of the horizontal axis to contain the complete trace.

Controls the appearance and scale of the Digital Phosphor Bitmap trace.

Sets the hit density r epresented by the top of the color scale. "Clipping" occurs for densities greater than this value.

Range: 1p% - 100%; Default: 100%.

Sets the hit density represented by the bottom of the color range. Range: 0 - 80%; Default: 0.

= 1), or it can be set to concentrate the resolution on the lower level of the range (Curve >

1) or the mapping can be set to show the best resolution on the upper range of density or hit count (Curve < 1).

RSA6100A Series Real-Time Spectrum Analyzers Help 67

General Signal Viewing > DPX Spectrum Density Tab – Option 200

DensityTab–O

The Density ta density of an area in the bitmap. The measurement box is also used by DPX Density triggering.

To measure the average signal density over a rectangular portion of the DPX bitmap, you can adjust the size and location of the measurement area using these controls, or by dragging the measurement box in the graph. You move the box by dragging the readout. You adjust the size of the box by dragging the corners or edges.

b speciﬁes the parameters of t he measurement box used for meas uring average signal

ption 200

Setting

Show Measurement Shows or hides the measurement box in the graph when Triggering is not set to DPX

Frequency

Amplitude

xxx

Description

Density. If Triggering is set to DPX Density, the measurement box is always visible.

Speciﬁes the frequency at the center of the measurement box. The +/- value speciﬁes the width of the measurement box.

Speciﬁes the amplitude of the center of the measurement box. The +/- value speciﬁes the height of the measurement box.

68 RSA6100A Series Real-Time Spectrum Analyzers Help

General S ignal Viewing > DPX Spectrum Audio Demod Tab

Audio Demod Ta

Audio demodul function with the Audio Demod tab. You access the Audio Demod tab from the Settings control panel of the DPX Spectrum display.

NOTE. Audio Demodulation is available only in real-time acquisition mode (not swept acquisition), and the Trigger mode must be set to Free Run (not Triggered).

Setting

On/Off Enables/disables audio demodulation.

Audio Gain Adjusts the volume of the demodulated audio.

Tune with

Receiver Freq

Receiver BW

xxx

AM / FM

ation can help you identify unknown radio signals. You control the audio demodulation

Description

Selects Amplitude Modulation as the demodulation method.

Selects Frequency Modulation as the demodulation method.

Speciﬁes how the frequency to be demodulated is speciﬁed. You can select markers or the frequency control.

Readout of the frequency to be demodulated.

Adjusts the equivalent receiver bandwidth for the audio demodulation. The range of values is 1 kHz to 500 kHz.

Note that these buttons select the demodulation method; they do not specify a frequency band.

Tune with

The choices for this setting are: one of the markers (MR, M1, M2, M3, M4) or the Frequency control (either the front-panel knob or the Freq control in the application).

To use a marker to specify the frequency to be demodulated:

1. Select Markers > Deﬁne Markers to display the Deﬁne Markers control panel.

2. Select Add to turn on the next marker.

RSA6100A Series Real-Time Spectrum Analyzers Help 69

General Signal Viewing > DPX Spectrum Audio Demod Tab

NOTE. The ﬁrst m readouts.

3. Select the trace to which the marker should be attached from the drop-down list.

4. Click Add to add additional markers. Assign them to the appropriate trace.

5. Click the close button to remove the Deﬁne Markers control panel.

Select markers. Select one of the markers in the Tune with drop-down list and then set the location of the

marker to the frequency you want to demodulate. If the marker you select is not enabled, the analyzer will tune to the frequency the marker was last set to.

arker deﬁned will always be MR. The MR marker is the reference for delta marker

Receiver BW

The Rece is too narrow, audio demodulation will be disabled. The following three cases illustrate the relationship between the Acquisition BW, Receiver Frequency, and Receiver BW.

Case 1. In this case, the upper limit of the Receiver BW exceeds the upper limit of the acquisition

bandwidth. When this occurs, audio demodulation is disabled and an error message is displayed.

iver BW setting will not change the acquisition bandwidth. Thus, if the acquisition bandwidth

Case 2. In this case, the upper and lower limits of the Receiver BW exceed the upper and lower limits

of the acquisition bandwidth. When this occurs, audio demodulation will be disabled and an error message is displayed.

70 RSA6100A Series Real-Time Spectrum Analyzers Help

General S ignal Viewing > DPX Spectrum Audio Demod Tab

Case 3. In this case, the upper and lower limits of the Receiver BW fall within the upper and lower

limits of the acquisition bandwidth. This is the desired relationship between the three settings, and audio demodulation is enabled.

RSA6100A Series Real-Time Spectrum Analyzers Help 71

General Signal Viewing > Time Overview Time Overview Display

Time Overview Display

The Time Overview display shows the entire acquisition record and shows you how the spectrum time and analysis time ﬁt within the acquisition record. This enables you to see how you can adjust the spectrum time and analysis time to measure portions of the data.

You can specify the maximum number of trace points in t he Time Overview display. You can set the maximum number of trace points to 1K, 10K, 100K, 1M points or to Never decimate. If the Acquisition Length includes more than 10,000 sample points (and Max trace points is not set to Never decimate), the trace is de points. This decimated trace is what is used for marker measurements.

cimated (using the +Peak method, similar to +Peak detection in a Spectrum display) to 10,000

The Time O is the period of time within the acquisition record over which the spectrum is calculated. The Analysis Length is the period of time within the acquisition record over which all other measurements (such as Amplitude vs. Time) are made. The Spectrum Length and Analysis Length can be locked together so that the data used to produce the Spectrum display is also used for measurement displays; however, they do not have to be tied together. They are by default speciﬁed separately and used to analyze different parts

verview window displays the Spectrum Length and Analysis Length. The Spectrum Length

of the acquisition record.

Elements of the Display

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General Signal Viewing > Time Overview Time Overview Display

Item Element Description

Analysis Time

Position and Scale

3 Amplitude vs. Time graph

4 Autoscale b

Horizontal Offset Adjusts the horizontal offset.

6 Results T

Horizontal Scale Adjusts the span of the graph. By decreasing the scale, the graph essentially

um Length and Offset

Spectr Indicator

9Actua

l length display

ysis Length and Offset

Anal Indicator

xxx

Setting Adjustment box Click in this box to adjust the value selected by the Analysis Time Control

utton

imeline

Control

Click a button

to select the value to be adjusted. In order, the buttons represent Analysis Offset, Analysis Length, Spectrum Offset, and Spectrum Length.

Adjusts the vertical scale and position.

The trace represents the entire acquisition record (at full horizontal scale). The graph in

dicates the Analysis Length or Spectrum Length on the graph

with a darker background.

Resets the h

orizontal scale to display the entire acquisition record and the

vertical scale to show all trace points.

This fuchsia line indicates the portion of the record actually used for calculating the selected result. For example: if a pulse measurement is selected

, it shows the period of the speciﬁc pulse. For a constellation display,

it shows the points included in the demodulation.

becomes a window that you can move over the acquisition record by adjusting

set.

the off

d line indicates the Spectrum Length and Offset. The longer the time,

This re the longer the bar. Adjusting the offset shifts the bar left or right.

Displays the actual time for the selected value. If the user-adjusted length extends past the end of the acquisition record, the realizable analysis length

s than requested.

is les

blue line indicates the Analysis Length and Offset. The longer the time,

This the longer the bar. Adjusting the offset shifts the bar left or right.

buttons.

NOTE. The area with black background (not gray) in the Amplitude vs. Time Graph highlights the control selected in the Analysis Time Control drop-down list.

Changing the Time Overview Display Settings (see page 74)

RSA6100A Series Real-Time Spectrum Analyzers Help 73

General Signal Viewing > Time Overview Time Overview Settings

Time Overview

Menu Bar: Setu

Front Panel / Application Toolbar: Settings

The Setup settings for Time Overview are shown in the following table.

Settings tab

Scale (see page 105) Adjusts the vertical and horizontal scale and offset of the display.

race (see page 74) Allows you to select the types of trace to display and its function.

Prefs (see page 106) Speciﬁes whether or not certain display elements are shown.

xxx

Trace Tab

The Trace Tab allows you to set the display characteristics of displayed traces.

Settings

p > Settings

Description

Setting

Show Shows / hides the selected trace.

Detection

Function

(Number of Traces) Sets the number of traces averaged to generate the displayed trace. (Present only

Freeze Halts updates to the selected trace.

Save Trace As Saves the selected trace to a ﬁle for later recall and analysis.

Show Recalled trace Displays a saved trace instead of a live trace.

xxx

Description

Sets the Detection method used for the trace. Not available for saved traces. Available detection methods are +Peak, -Peak, +/-Peak, Avg (VRMS), and Sample. Not all detection methods are available in all displays.

Selects the trace processing method. Available settings are: Normal, Average, Max Hold, and Min Hold.

when Function is set to Average.)

74 RSA6100A Series Real-Time Spectrum Analyzers Help

General Signal Viewing > Time Overview Trace Tab

Detection

Trace Detection occurs when t he trace is being decimated by the measurement. For example, if the maximum numbe measurement must decimate the 200,000 resulting trace points by 2 to prevent exceeding the 100,000 trace point limit. Since only one value can be selected for each trace point, an algorithm must be used to select (detect) the appropriate value to use.

The IQ samples in a data acquisition can be detected in a variety of ways. The number of IQ samples available to each trace point varies with both analysis length and trace length. For example, with Spectrum Length set to ‘Auto’ in the Analysis menu, the instrument analyzes just enough samples to produce one IQ sample pair per trace point. In this case, the detection method chosen has very little effect, as the +Peak, -P

eak, Avg (VRMS) and Sample values are all equal. Changing the Spectrum Length causes the available detection methods to differ in value because they have a larger set of samples for the various detection methods to process.

The available detection methods (depending on the display) are:

r of trace points is 100,000, and the selected analysis region is 200,000 samples, the

+Peak –

Each point on the trace is the result of detecting the positive peak value present in the set of

IQ samples available to that trace point.

– Each point on the trace is the result of detecting the negative peak value present in the set of

-Peak

IQ samples available to that trace point.

ak – S elects the highest and lowest values of all the samples contained in two consecutive

+/-Pe

acquisition intervals.

VRMS) [Average V

Avg (

] – Each point on the trace is the result of determining the RMS Voltage

RMS

Sample – The result is calculated based on the ﬁrst sample available in the set of IQ samples for each trace point.

race Processing

Traces can be processed to display in different ways. The Function setting controls trace processing.

Normal - Each new trace is displayed and then replaced by the next trace. Each data point contains a single vertical value.

Average - Multiple traces are averaged together to generate the displayed trace. There is one vertical value for each underlying frequency data point. Once the speciﬁed number of traces have been acquired and averaged to generate the displayed trac e, each new trace takes the place of the oldest trace in the calculation. The Number of Traces setting speciﬁes how many traces averaged.

RSA6100A Series Real-Time Spectrum Analyzers Help 75

General Signal Viewing > Time Overview Trace Tab

Max Hold -Displ display point is compared to the previous maximum value and the greater value is retained for display and subsequent comparisons.

Min Hold - Displays the minimum value in the trace record for each display point. Each new trace display point is compared to the previous minimum value and the lesser value is retained for display and subsequent comparisons.

ays the maximum value in the trace record for each display point. Each new trace

Saving Traces

To save a trace for later analysis:

1. Select the Save Trace As button. This displays the Save As dialog box.

2. Navigate to the desired folder or use the default.

3. Type a name for the saved trace and click Save.

Recalling Traces

You can recall a previously saved trace for analysis or comparison to a live trace.

To select a trace for recall:

1. Select the trace into which the recalled trace will be loaded, from the Trace drop-down list.

2. Check the Show check box.

3. Click the ... button to display the Open dialog box.

76 RSA6100A Series Real-Time Spectrum Analyzers Help

General Signal Viewing > Time Overview Trace Tab

4. Navigate to the

5. Check the Show Recalled Trace check box.

6. Verify that the trace’s Show check box is selected (either on this tab or next to the drop-down list

located at the top-left corner of the graph).

desired ﬁle and click Open.

RSA6100A Series Real-Time Spectrum Analyzers Help 77

General Signal Viewing > Spectrum Spectrum Display

Spectrum Display

To display a spectrum:

1. Click the Displays button or select Setup > Displays.

2. From the Fol

3. Double-click the Spectrum icon in the Available displays box. This adds the Spectrum icon to the

Selected d

the Spectrum icon and then click the Add button to select Spectrum for display.

4. Click the

ders box, select General Signal Viewing.

isplays box (and removes it f rom the Available displays box). Alternatively, you can click

OK button.

Elements of the Spectrum Display

78 RSA6100A Series Real-Time Spectrum Analyzers Help

General Signal Viewing > Spectrum Spectrum Display

Item Display elemen

Vert Offset Sets the top of

Description

graph value. This is only a visual control for panning the graph. The Reference Level is adjusted in the Toolbar and the Ampl control panel. By default, Vert Offset = Ref Level.

3RBW

4 VBW

dB/div Sets the vertical scale value. The maximum value is 20.00 dB/division.

Sets the resolution bandwidth. Note that when the RBW is set to Auto, its value is ita

Enables the

licized.

VBW (Video Bandwidth) ﬁlter. See Setup > Settings > B

(see page 103).

Autoscale Adjusts th

e Vertical and Horizontal scaling to display the entire trace on

screen.

6 Position

Default function is CF - center frequency (equivalent to the Freq setting). If Horizontal scaling has been manually adjusted in Settings > Scale, then Offset wi

Span / Sc

ale

Default

ll replace CF as the setting at the bottom-left corner of the screen.

function is Span - frequency difference between the left edge of the display and the right edge. If Horizontal scaling has been manually adjusted in Settings > Scale, then Scale will replace Span as the setting at

tom-right corner of the screen.

the bot

Clear Restar

9 Function

Show Contr

ts multi-trace functions (Avg, Hold).

ut of the Detection and Function selections for the selected trace.

Reado

ols whether the selected Trace is visible or not. When trace is Off, the

box is not checked.

11 Trac

Selects a trace. Touching here pops up a context m enu listing the available traces, whether they are enabled or not. If user selects a trace that is not

ently enabled, it will be made enabled.

curr

xxx

Touchscreen Actions on Markers in the Graph Area

W Tab

Action Description

Mouse click within 1/2 div. of

Selects the marker and updates the marker display to show the selected marker’s values.

amarker

Touch marker to select and

Adjust the setting associated with the Marker.

then use knob, or arrow keys

Touch and drag a marker

xxx

Changes marker position to the "drop point".

Changing the Spectrum Display Settings (see page 80)

RSA6100A Series Real-Time Spectrum Analyzers Help 79

General Signal Viewing > Spectrum Spectrum Settings

Spectrum Sett

Menu Bar: Setu

Front Panel / Application Toolbar: Settings

The Setup settings for the Spectrum display are visible when Spectrum is the selected display.

Settings tab

Freq & Span (see page 98) Sets frequency and span parameters for the Spectrum Analysis display.

W (see page 1 03) Sets Resolution Bandwidth and windowing parameters.

Traces (see page 99) Sets Trace display parameters.

Traces (Math) (see page 103) Sets the traces used to create the Math trace.

Scale Tab (see page 81) Sets vertical and horizontal scale and position parameters.

Prefs Tab (see page 106) Speciﬁes whether or not certain display elements are shown.

xxx

ings

p > Settings

Description

80 RSA6100A Series Real-Time Spectrum Analyzers Help

General Signal Viewing > Spectrum Scale Tab

Scale Tab

The Scale tab a

llows you to change the vertical scale settings. Changing the scale settings changes how the trace appears on the display but does not change control settings such as Measurement Frequency. In effect, these controls operate like pan and zoom controls.

Setting

Vertical

Scale Changes the vertical s cale.

Position

Autoscale

Horizontal

Scale Allows you to change the range of frequencies shown in the graph without changing the

Position Allows you pan the graph.

Autoscale

Reset Scale Resets all settings to their default values.

Log scale

xxx

Description

Vertical Position adjusts the top of graph amplitude value. This control allows you to move (“pan”) the traces up and down in the graph without changing the Reference Level.

Resets the Offset so that the trace appears below the top of the graph.

span or measurement frequency.

Resets Scale to the Span setting.

Resets the display to show the frequency axis in a logarithmic scale.

RSA6100A Series Real-Time Spectrum Analyzers Help 81

General Signal Viewing > Spectrogram Spectrogram Display

Spectrogram Display

The Spectrogram is a display with the vertical axis (time) composed of successive spectral displays, each having the amplitude represented by color or intensity. The horizontal axis represents frequency. The most recently acquired spectrum results are added to the bottom of the spectrogram. The addition of a new spectrum can occur at the fastest rate that new spectra can be plotted, or, if you choose, new spectra can be added at a ti The maximum number of lines that can be displayed in a spectrogram is 125,000.

The spectrogram can also be displayed in a 3-D waterfall format. In the 3-D waterfall format, the spectrogram displays the time axis along a simulated Z-axis.

NOTE. Spectrogram data is shared with the Spectrum display. There is no linkage between DPX and Spectrogram.

To display a Spectrogram:

med rate. The spectrogram view is well-suited to displaying long-term trends of spectral data.

1. Select the Displays button or select Setup > Displays. This displays the Select Displays dialog box.

2. From the Folders box, select GeneralSignalViewing.

3. Double-click the Spectrogram icon in the Available Displays box. This adds the Spectrogram icon

to the Selected displays box.

4. Click the OK button. This displays the spectrogram view.

5. To display a 3-D version of the spectrogram, select the 3-D checkbox.

Elements of the Spectrogram Display

82 RSA6100A Series Real-Time Spectrum Analyzers Help

General Signal Viewing > Spectrogram Spectrogram Display

Item Display element Description

3RBW

4 VBW

8 Pos

9 Autoscale

13 Position scroll bar

Check mark indicator The check mark indicator in the upper, left-hand corner of the display shows

when the Spectrogram display is the optimized display.

Time/div Sets the length of time represented by each vertical division. Divisions are

indicated by tick marks along the left edge of the graph.

Sets the resolution bandwidth. Note that when the RBW is set to Auto, its value is italicized.

Enables the VBW (Video Bandwidth) ﬁlter. See Setup > Settings > B

(see page 103).

3-D checkbox Enables and disables the 3-D view.

Selected records indicators Shows the positions of the start and stop records selected on the Select data

records tab. Drag the indicators to select which records will be played by Replay All. Note that these are not visible while acquisitions are running; the instrument must be stopped for the indicators to be visible.

T Trigger indicator. This icon indicates the trigger point within the current

acquisition.

Position indicates the bottom line visible in graph. Changing this setting scrolls the window up and down through the displayed acquisition records.

Resets Vertical and Horizontal scale and Pos to default values.

CF Sets the Center Frequency.

Span Sets the span of the spectrogram display.

Current data record indicator

A blue line indicates the current data record. When the analysis length is short, the blue line appears as a thin line much like the selected indicator line. When the analysis length is relatively long, the blue line appears more like a blue bar.

Changes the position of the trace i n the window. Changing the position scroll bar is the same as adjusting the Pos setting.

W Tab

RSA6100A Series Real-Time Spectrum Analyzers Help 83

General Signal Viewing > Spectrogram Spectrogram Display

cator

cators

Description

This inversethe Spectrum display when the Spectrogram trace is enabled. This line is attached to the selected marker.

remain in mem Acquisition Data Info > Delete All Data.

These icons indicate the position of markers in the spectrogram. You can move markers by dragging the desired marker indicator.

Displays the selected Detection method (see S tab).

Marker re marker readout includes a date and timestamp. The time is displayed in a 24-hour format. The timestamp readout can be shown or hidden independ

page 106)).

Spectrums/line, and Overlap. See T

colored line indicates the Spectrogram line that will appear in

ory and are available for replay. To clear memory, select File >

adout for the selected marker. In the S pectrogram display, the

ently of the other marker readouts (see S

ime Scale Status Readout (see page 84).

Item Display elemen

16 Marker indi

17 Detection setting

18 Marker readout

xxx

Selected indi

Clear Clears the spectrogram display; however, data records in acquisition history

Time Scale status readout Three readouts can appear here depending on settings: Time/update,

Time Scale Status Readout

Three types of readouts can appear in the display depending on settings:

ettings > Trace (see page 85)

ettings > Prefs (see

Time/update – Displays minutes:seconds when Spectrum Monitor is selected in the Settings > Time &FreqScaletabintheVertical (Time) section.

Spectrums/line – Displays an integer number when vertical scale is Normal and each line contains the results from one or more frequency transforms (whether zoomed out or not).

Overlap – Displays the overlap percentage when vertical scale is Normal and each line’s transform shares some points with the transforms of lines before and after it (zoomed in). Overlap can only be done when the Analysis Length > 2x RBW frame length.

The Spectrogram can show results from one or multiple acquisitions and it can show one or multiple lines for each acquisition.

hanging the Spectrogram Display Settings (see page 85)

84 RSA6100A Series Real-Time Spectrum Analyzers Help

General Signal Viewing > Spectrogram Spectrogram Settings

Spectrogram S

Menu Bar: Setu

Front Panel / Application Toolbar: Settings

The Setup settings for the Spectrogram display are visible when Spectrogram is the selected display.

Settings tab

Freq & Span (see page 98) Sets frequency and span parameters for the Spectrogram display.

W (see page 1 03) Sets Resolution Bandwidth and windowing parameters.

Trace (see page 85) Sets Trace display parameters.

Amplitude Scale (see page 86) Selects between 2-D and 3-D, sets height scale, position and orientation for 3-D display.

Time & Fr page 86)

Prefs (see page 106) Speciﬁes whether or not certain display elements are shown.

xxx

eq Scale (see

Trace Tab

ettings

p > Settings

Description

or parameters for the spectrogram trace.

Sets col

Sets the Spectrum Monitor controls are also on this tab.

vertical and horizontal scale parameters for the spectrogram trace. The

The Spectrogram Trace tab controls let you specify the Detection method, save traces, and recall sa ved traces for display. The Spectrogram Trace tab does not have all the controls that other Trace tabs contain, however, it does have a unique display element, the Selected Line readout. For details on Detection, Freeze, and saving and recalling traces, see the T

races Tab (see page 99).

Selected Line

Displays the time at the Selected Line. If Markers are enabled, the selected line is positioned by the selected marker. If no markers are enabled, the selected line is the ﬁrst line in the current analysis period.

RSA6100A Series Real-Time Spectrum Analyzers Help 85

General Signal Viewing > Spectrogram Amplitude Scale Tab

Amplitude Sca

The Amplitude Waterfall display, and set the color scheme used for the spectrogram trace.

Setting

Height (3-D only)

Scale C hanges the vertical scale for trace Amplitude in the graph (not the vertical scale for

Position

ale

Autosc

3–D Waterfall Displays the spectrogram in a 3-D format.

Northeast

Northwest

et Scale

Res

or (Power)

Col

lor

xxx

le Tab

Scale tab allows you to change the vertical and horizontal scale settings, enable the 3-D

Description

Time).

es the level displayed at the bottom edge of the graph. (Bottom front edge in

Speciﬁ the 3-D view).

Adjusts the vertical position and scale of the trace lines to bring them into the visible portion of the graph.

Shifts the perspective of the 3-D graph so that the oldest traces move back and to the

righ

ts the perspective of the 3-D graph so that the oldest traces move back and to the left.

Shif

ets the Height and Color settings to their default values.

Res

splays a drop-down list that allows you to set the color scheme used for the

Di spectrogram trace.

Sets the maximum power level represented by the top of the color scale.

Sets the minimum power level represented by the bottom of the color scale.

Time & Freq Scale Tab

The Time and Freq Scale tab allows you to change the vertical and horizontal scale settings, enable the 3-D Waterfall display, and set the color scheme used for the spectrogram trace.

86 RSA6100A Series Real-Time Spectrum Analyzers Help

General Signal Viewing > Spectrogram Time & Freq Scale Tab

Setting

Vertical (Time)

Normal

Spectrum Monitor

Time/update Sets the time, in minutes and seconds, r epresented by each line of the spectrogram.

Reset Scale Resets the Time/div and Pos settings to their default values.

Autoscale

Time/div Sets the time displayed per division.

Visible elapsed time

Position

Time at position

Horizontal (Frequency)

Scale Sets the frequency range of the graph without changing the Span value.

Position

Autoscale

xxx

Description

For most Spectrogram applications. Primary time scale control is Time/div. Time scale can be zoomed in or out.

For long-term signal monitoring applications. In spectrum monitor mode, each line in the spectrogram represents the period of time speciﬁed by the Time/update parameter. Time scale can be zoomed out, but not zoomed in (no overlap).

Only available in Spectrum Monitor.

Scales the vertical (time) axis to compress all exis ting trace lines into the visible area of the graph. Resets the Position value to zero, placing the m ost recent spectrogram line at the bottom of the spectrogram display. Only Position is affected by Autoscale when Spectrum Monitor is selected.

Displays the length of time visible in the display. This does not represent the total time available to view.

Adjusts vertical position of the trace within the graph area. Setting represents the offset, in divisions, between the bottom of the graph and the bottom (most recent) line in the results trace.

Displays the time of the spectrogram line shown at the bottom of the graph. This time is relative to the Time Zero Reference of the current acquisition.

Sets the frequency displayed at the center of the graph. Changing this value does not change the Freq setting.

Sets the frequency scale to the Spectrogram Span value.

Spectrum Monitor

Spectrum Monitor performs long term monitoring. The monitor mode compresses time into each line of the spectrogram, which enables you to monitor long periods o f time (from 1 second per line up to 600 minutes per line). With extended memory (Option 02) installed in the instrument, you can capture up to 125,000 lines. With standard memory installed in the instrument, the maximum number of lines you can capture is 31,250.

During each line’s collection period, spectrum transforms are computed for each acquisition taken by the instrument. As each transform completes, it is incorporated into the current spectrogram line. How each

RSA6100A Series Real-Time Spectrum Analyzers Help 87

General Signal Viewing > Spectrogram Time & Freq Scale Tab

line of the spec Trace). For example, if Detection is set to +Peak, each spectrogram line is effectively a peak hold display of all t he spectral data captured since the prior line.

trogram is created in spectrum monitor mode depends on the detection setting (Settings >

88 RSA6100A Series Real-Time Spectrum Analyzers Help

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