R&S®FSMR3-K70
Vector Signal Analysis
User Manual
(;ÝR?2)
1179341502
Version 02
This document describes the following R&S®FSMR3000 models:
●
R&S®FSMR3008 (1345.4004K08)
●
R&S®FSMR3026 (1345.4004K26)
●
R&S®FSMR3050 (1345.4004K50)
The contents of this manual correspond to firmware version 1.10 and higher.
The following firmware options are described:
●
R&S FSMR3-K70 (1345.3150.02) (requires R&S FSMR3-B1)
●
R&S FSMR3-K70M (1345.3737.02) (requires R&S FSMR3-K70)
●
R&S FSMR3-K70P (1345.3720.02) (requires R&S FSMR3-K70)
© 2022 Rohde & Schwarz GmbH & Co. KG
Muehldorfstr. 15, 81671 Muenchen, Germany
Phone: +49 89 41 29 - 0
Email: info@rohde-schwarz.com
Internet: www.rohde-schwarz.com
Subject to change – data without tolerance limits is not binding.
R&S® is a registered trademark of Rohde & Schwarz GmbH & Co. KG.
Trade names are trademarks of the owners.
1179.3415.02 | Version 02 | R&S®FSMR3-K70
Throughout this manual, products from Rohde & Schwarz are indicated without the ® symbol , e.g. R&S®FSMR3 is indicated as
R&S FSMR3.
R&S®FSMR3-K70
1 Documentation overview.....................................................................13
1.1 Getting started manual............................................................................................... 13
1.2 User manuals and help...............................................................................................13
1.3 Service manual............................................................................................................13
1.4 Instrument security procedures................................................................................ 14
1.5 Printed safety instructions.........................................................................................14
1.6 Data sheets and brochures........................................................................................ 14
1.7 Release notes and open-source acknowledgment (OSA).......................................14
1.8 Application notes, application cards, white papers, etc......................................... 14
2 Welcome to the R&S FSMR3000 VSA application............................ 15
Contents
Contents
2.1 Introduction to vector signal analysis...................................................................... 16
2.2 Starting the VSA application......................................................................................17
2.3 Understanding the display information.................................................................... 17
3 Measurements and result displays.................................................... 20
3.1 Evaluation data sources in VSA................................................................................ 20
3.2 Result types in VSA.................................................................................................... 24
3.2.1 Bit error rate (BER)....................................................................................................... 26
3.2.2 Channel frequency response group delay.................................................................... 28
3.2.3 Channel frequency response magnitude...................................................................... 29
3.2.4 Constellation frequency.................................................................................................30
3.2.5 Constellation I/Q............................................................................................................30
3.2.6 Constellation I/Q (rotated)............................................................................................. 32
3.2.7 Error vector magnitude (EVM)...................................................................................... 33
3.2.8 Eye diagram frequency................................................................................................. 34
3.2.9 Eye diagram imag (Q)................................................................................................... 35
3.2.10 Eye diagram real (I).......................................................................................................37
3.2.11 Frequency absolute.......................................................................................................38
3.2.12 Frequency relative.........................................................................................................39
3.2.13 Frequency error absolute.............................................................................................. 40
3.2.14 Frequency error relative................................................................................................ 42
3.2.15 Frequency response group delay..................................................................................43
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3.2.16 Frequency response magnitude....................................................................................44
3.2.17 Frequency response phase...........................................................................................44
3.2.18 Impulse response magnitude........................................................................................ 45
3.2.19 Impulse response phase............................................................................................... 46
3.2.20 Impulse response real/imag.......................................................................................... 47
3.2.21 Magnitude absolute.......................................................................................................47
3.2.22 Magnitude overview (capture buffer).............................................................................49
3.2.23 Magnitude relative.........................................................................................................50
3.2.24 Magnitude error.............................................................................................................51
3.2.25 Phase error................................................................................................................... 52
3.2.26 Phase wrap................................................................................................................... 53
3.2.27 Phase unwrap............................................................................................................... 54
3.2.28 Real/imag (I/Q)..............................................................................................................55
Contents
3.2.29 Result summary............................................................................................................ 56
3.2.30 Spectrum (capture buffer + error)..................................................................................59
3.2.31 Spectrum (measurement + error)..................................................................................61
3.2.32 Symbol table................................................................................................................. 62
3.2.33 Vector frequency........................................................................................................... 63
3.2.34 Vector I/Q...................................................................................................................... 64
3.3 Predefined display configuration.............................................................................. 66
3.4 Common parameters in VSA......................................................................................67
4 Measurement basics............................................................................69
4.1 Filters and bandwidths during signal processing................................................... 69
4.1.1 I/Q bandwidth................................................................................................................ 70
4.1.2 Demodulation bandwidth (measurement bandwidth)....................................................71
4.1.3 Modulation and demodulation filters............................................................................. 71
4.1.4 Measurement filters.......................................................................................................72
4.1.5 Customized filters..........................................................................................................74
4.2 Sample rate, symbol rate and I/Q bandwidth........................................................... 76
4.2.1 Sample rate and maximum usable I/Q bandwidth for RF input.....................................77
4.2.1.1 Relationship between sample rate, record length and usable I/Q bandwidth............... 78
4.3 Symbol mapping......................................................................................................... 78
4.3.1 Phase shift keying (PSK).............................................................................................. 79
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4.3.2 Rotating PSK.................................................................................................................83
4.3.3 Differential PSK.............................................................................................................86
4.3.4 Rotating differential PSK modulation.............................................................................87
4.3.5 Offset QPSK..................................................................................................................89
4.3.6 Shaped offset QPSK..................................................................................................... 90
4.3.7 Frequency shift keying (FSK)........................................................................................91
4.3.8 Minimum shift keying (MSK)......................................................................................... 95
4.3.9 Quadrature amplitude modulation (QAM)..................................................................... 96
4.3.10 ASK............................................................................................................................. 108
4.3.11 APSK...........................................................................................................................109
4.3.12 User-defined modulation............................................................................................. 110
4.4 Overview of the demodulation process.................................................................. 111
4.4.1 Burst search................................................................................................................ 114
Contents
4.4.2 I/Q pattern search........................................................................................................115
4.4.3 Demodulation and symbol decisions...........................................................................116
4.4.4 Pattern symbol check.................................................................................................. 118
4.4.5 Synchronization and the reference signal................................................................... 119
4.4.6 The equalizer.............................................................................................................. 121
4.5 Signal model, estimation and modulation errors...................................................123
4.5.1 PSK, QAM and MSK modulation................................................................................ 124
4.5.1.1 Error model................................................................................................................. 124
4.5.1.2 Estimation................................................................................................................... 125
4.5.1.3 Modulation errors........................................................................................................ 126
4.5.2 FSK modulation...........................................................................................................135
4.5.2.1 Error model................................................................................................................. 137
4.5.2.2 Estimation................................................................................................................... 138
4.5.2.3 Modulation errors........................................................................................................ 139
4.6 Measurement ranges................................................................................................ 140
4.6.1 Result range................................................................................................................141
4.6.2 Evaluation range......................................................................................................... 143
4.7 Display points vs estimation points per symbol....................................................145
4.8 Capture buffer display.............................................................................................. 146
4.9 Known data files - dependencies and restrictions................................................ 148
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4.10 Known data from PRBS generators........................................................................ 149
4.11 Multi-modulation analysis (R&S FSMR3-K70M).....................................................151
4.12 I/Q data import and export....................................................................................... 157
5 Configuration......................................................................................158
5.1 Configuration overview............................................................................................ 158
5.2 Configuration according to digital standards........................................................ 162
5.3 Signal description..................................................................................................... 163
5.3.1 Modulation...................................................................................................................164
5.3.2 Signal structure........................................................................................................... 167
5.3.3 Frame structure...........................................................................................................170
5.3.3.1 General frame structure settings.................................................................................171
5.3.3.2 Frame configuration.................................................................................................... 173
Contents
5.3.4 Known data................................................................................................................. 178
5.4 Input, output and frontend settings.........................................................................180
5.4.1 Input settings...............................................................................................................181
5.4.1.1 Radio frequency input................................................................................................. 181
5.4.1.2 Settings for input from I/Q data files............................................................................183
5.4.2 Output settings............................................................................................................ 184
5.4.2.1 General output configuration.......................................................................................184
5.4.2.2 DC power output configuration....................................................................................187
5.4.2.3 Signal source output configuration..............................................................................187
5.4.2.4 How to output a trigger signal..................................................................................... 187
5.4.3 Frequency settings......................................................................................................188
5.4.4 Amplitude and vertical axis configuration....................................................................189
5.4.4.1 Amplitude settings.......................................................................................................189
5.4.4.2 Scaling........................................................................................................................ 193
5.4.4.3 Units............................................................................................................................ 197
5.5 Signal capture........................................................................................................... 197
5.5.1 Data acquisition...........................................................................................................198
5.5.2 Trigger settings............................................................................................................200
5.5.3 Sweep settings............................................................................................................203
5.6 Burst and pattern configuration.............................................................................. 206
5.6.1 Burst search................................................................................................................ 206
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5.6.2 Pattern search.............................................................................................................208
5.6.3 Pattern configuration................................................................................................... 210
5.6.4 Pattern definition......................................................................................................... 213
5.7 Result range configuration...................................................................................... 216
5.8 Demodulation settings............................................................................................. 218
5.8.1 Demodulation - compensation and equalizer..............................................................218
5.8.2 Advanced demodulation (synchronization)................................................................. 222
5.9 Measurement filter settings..................................................................................... 226
5.10 Evaluation range configuration............................................................................... 227
5.11 Adjusting settings automatically.............................................................................229
5.12 Restoring factory settings for vector signal analysis........................................... 231
6 Analysis.............................................................................................. 232
Contents
6.1 Trace settings............................................................................................................232
6.2 Trace export settings................................................................................................236
6.3 Markers...................................................................................................................... 237
6.3.1 Individual marker settings........................................................................................... 237
6.3.2 Marker search settings................................................................................................239
6.3.3 Marker positioning functions....................................................................................... 241
6.4 Limit and display lines..............................................................................................242
6.4.1 Display lines for eye diagrams.................................................................................... 242
6.4.2 Modulation accuracy limit lines................................................................................... 243
6.5 Display and window configuration..........................................................................246
6.5.1 Result window configuration....................................................................................... 246
7 I/Q data import and export................................................................ 250
8 How to perform vector signal analysis............................................ 251
8.1 How to perform VSA according to digital standards.............................................251
8.2 How to perform customized VSA measurements.................................................. 253
8.2.1 How to define the result range.................................................................................... 254
8.2.2 How to select user-defined filters................................................................................ 255
8.2.3 How to perform pattern searches................................................................................256
8.2.3.1 How to assign patterns to a standard..........................................................................257
8.2.3.2 How to define a new pattern....................................................................................... 257
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8.2.3.3 How to manage patterns............................................................................................. 260
8.2.4 How to work with known data files.............................................................................. 261
8.2.4.1 How to load known data files...................................................................................... 262
8.2.4.2 How to create known data files................................................................................... 262
8.2.5 How to work with PRBS as known data...................................................................... 264
8.3 How to analyze the measured data......................................................................... 265
8.3.1 How to change the display scaling..............................................................................266
8.3.1.1 How to scale time and spectrum diagrams................................................................. 266
8.3.1.2 How to scale statistics diagrams................................................................................. 267
8.3.2 How to measure the size of an eye.............................................................................269
8.3.3 How to check limits for modulation accuracy.............................................................. 270
8.3.4 How to export the trace data to a file.......................................................................... 271
Contents
9 Measurement examples.....................................................................272
9.1 Connecting the transmitter and analyzer............................................................... 272
9.2 Measurement example 1: continuous QPSK signal.............................................. 273
9.2.1 Transmitter settings.....................................................................................................273
9.2.2 Analyzer settings.........................................................................................................274
9.2.3 Changing the display configuration............................................................................. 275
9.2.4 Navigating through the capture buffer.........................................................................276
9.2.5 Averaging several evaluations.................................................................................... 277
9.3 Measurement example 2: burst GSM EDGE signals..............................................278
9.3.1 Transmitter settings.....................................................................................................278
9.3.2 Analyzer settings.........................................................................................................280
9.3.3 Navigating through the capture buffer.........................................................................281
9.3.4 Evaluating the rising and falling edges........................................................................282
9.3.5 Setting the evaluation range....................................................................................... 283
9.3.6 Comparing the measurement signal to the reference signal.......................................284
10 Troubleshooting the measurement.................................................. 286
10.1 Flow chart for troubleshooting................................................................................ 286
10.2 Explanation of status bar messages.......................................................................288
10.3 Frequently asked questions.....................................................................................296
10.3.1 Issues with graphical results....................................................................................... 297
10.3.2 Issues with numeric results......................................................................................... 301
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10.3.3 Synchronization and demodulation problems............................................................. 306
11 Remote commands for VSA..............................................................308
11.1 Introduction............................................................................................................... 308
11.1.1 Conventions used in descriptions............................................................................... 309
11.1.2 Long and short form.................................................................................................... 310
11.1.3 Numeric suffixes..........................................................................................................310
11.1.4 Optional keywords.......................................................................................................310
11.1.5 Alternative keywords................................................................................................... 311
11.1.6 SCPI parameters.........................................................................................................311
11.1.6.1 Numeric values............................................................................................................311
11.1.6.2 Boolean....................................................................................................................... 312
11.1.6.3 Character data............................................................................................................ 312
Contents
11.1.6.4 Character strings.........................................................................................................313
11.1.6.5 Block data................................................................................................................... 313
11.2 Common suffixes......................................................................................................313
11.3 Activating vector signal analysis............................................................................ 313
11.4 Digital standards.......................................................................................................317
11.5 Configuring VSA....................................................................................................... 319
11.5.1 Signal description........................................................................................................319
11.5.1.1 Modulation...................................................................................................................320
11.5.1.2 Signal structure........................................................................................................... 328
11.5.1.3 Frame structure...........................................................................................................331
11.5.1.4 Known data................................................................................................................. 342
11.5.2 Input, output and frontend settings..............................................................................346
11.5.2.1 RF input.......................................................................................................................346
11.5.2.2 Configuring file input................................................................................................... 350
11.5.2.3 Output settings............................................................................................................ 350
11.5.2.4 Configuring the trigger output......................................................................................351
11.5.2.5 Frequency................................................................................................................... 354
11.5.2.6 Amplitude settings.......................................................................................................355
11.5.2.7 Scaling and units.........................................................................................................359
11.5.3 Signal capture............................................................................................................. 365
11.5.4 Triggering measurements........................................................................................... 368
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11.5.5 Configuring sweeps.....................................................................................................372
11.5.6 Configuring bursts and patterns.................................................................................. 374
11.5.6.1 Burst search................................................................................................................ 374
11.5.6.2 Pattern searches......................................................................................................... 376
11.5.6.3 Configuring patterns....................................................................................................378
11.5.7 Defining the result range............................................................................................. 381
11.5.8 Demodulation settings.................................................................................................384
11.5.9 Measurement filter settings......................................................................................... 393
11.5.10 Defining the evaluation range..................................................................................... 395
11.5.11 Adjusting settings automatically.................................................................................. 396
11.6 Performing a measurement......................................................................................399
11.7 Analysis..................................................................................................................... 403
11.7.1 Configuring traces....................................................................................................... 403
Contents
11.7.2 Working with markers..................................................................................................407
11.7.2.1 Individual marker settings........................................................................................... 407
11.7.2.2 Marker search and positioning settings.......................................................................412
11.7.3 Configuring display lines for eye diagrams................................................................. 419
11.7.4 Configuring modulation accuracy limit lines................................................................ 423
11.7.4.1 General commands.....................................................................................................424
11.7.4.2 Defining limits..............................................................................................................424
11.8 Configuring the result display................................................................................. 429
11.8.1 General window commands........................................................................................429
11.8.2 Working with windows in the display...........................................................................431
11.8.3 VSA window configuration.......................................................................................... 437
11.9 Retrieving results......................................................................................................445
11.9.1 Retrieving trace data and marker values.................................................................... 445
11.9.2 Measurement results for TRACe<n>[:DATA]? TRACE<n>.........................................451
11.9.2.1 Capture buffer results..................................................................................................451
11.9.2.2 Cartesian diagrams..................................................................................................... 451
11.9.2.3 Polar diagrams............................................................................................................ 452
11.9.2.4 Symbols...................................................................................................................... 452
11.9.2.5 Result summary.......................................................................................................... 452
11.9.2.6 Equalizer..................................................................................................................... 453
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11.9.2.7 Multi source.................................................................................................................453
11.9.3 Retrieving general burst and pattern information........................................................ 453
11.9.4 Retrieving parameter values....................................................................................... 458
11.9.5 Retrieving limit check results.......................................................................................473
11.10 Importing and exporting I/Q data and results........................................................ 475
11.11 Status reporting system........................................................................................... 476
11.11.1 STATus:QUEStionable:SYNC<n> register..................................................................479
11.11.2 STATus:QUEStionable:MODulation<n> register.........................................................479
11.11.3 STATus:QUESTionable:MODulation<n>:EVM register............................................... 479
11.11.4 STATus:QUESTionable:MODulation<n>:PHASe register........................................... 480
11.11.5 STATus:QUESTionable:MODulation<n>:MAGnitude register.....................................480
11.11.6 STATus:QUESTionable:MODulation<n>:CFRequency register..................................481
11.11.7 STATus:QUESTionable:MODulation<n>:IQRHO register........................................... 481
Contents
11.11.8 STATus:QUESTionable:MODulation<n>:FSK register................................................482
11.11.9 Querying the status registers...................................................................................... 482
11.12 Deprecated commands.............................................................................................487
11.13 Programming examples........................................................................................... 488
11.13.1 Measurement example 1: user-defined measurement of continuous QPSK signal....489
11.13.2 Measurement example 2: GSM EDGE burst measurement based on a digital standard
.................................................................................................................................... 490
11.13.3 Measurement example 3: user-defined pattern search and limit check......................493
Annex.................................................................................................. 496
A Abbreviations..................................................................................... 496
B Predefined standards and settings.................................................. 497
C Predefined measurement and tx filters............................................506
C.1 Transmit filters.......................................................................................................... 506
C.2 Measurement filters.................................................................................................. 507
C.3 Typical combinations of tx and measurement filters.............................................508
D ASCII file export format for VSA data...............................................509
E Known data file syntax description..................................................511
F Formulae.............................................................................................513
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F.1 Trace-based evaluations.......................................................................................... 513
F.2 Result summary evaluations................................................................................... 515
F.2.1 PSK, QAM and MSK modulation................................................................................ 515
F.2.2 FSK modulation...........................................................................................................517
F.3 Statistical evaluations for the result summary...................................................... 518
F.4 Trace averaging.........................................................................................................518
F.5 Analytically calculated filters................................................................................... 519
F.6 Standard-specific filters........................................................................................... 520
F.6.1 Transmit filter...............................................................................................................520
F.6.2 Measurement filter...................................................................................................... 520
F.6.2.1 EDGE measurement filters......................................................................................... 520
F.6.2.2 Low-isi filters............................................................................................................... 523
Contents
List of Remote Commands (VSA).....................................................527
Index....................................................................................................538
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1 Documentation overview
1.1 Getting started manual
Documentation overview
Service manual
This section provides an overview of the R&S FSMR3 user documentation. Unless
specified otherwise, you find the documents on the R&S FSMR3 product page at:
www.rohde-schwarz.com/product/FSMR3000.html/
Introduces the R&S FSMR3 and describes how to set up and start working with the
product. Includes basic operations, typical measurement examples, and general information, e.g. safety instructions, etc.
A printed version is delivered with the instrument. A PDF version is available for download on the Internet.
1.2 User manuals and help
Separate user manuals are provided for the base unit and the firmware applications:
●
Base unit manual
Contains the description of all instrument modes and functions. It also provides an
introduction to remote control, a complete description of the remote control commands with programming examples, and information on maintenance, instrument
interfaces and error messages.
●
Firmware application manual
Contains the description of the specific functions of a firmware application, including remote control commands. Basic information on operating the R&S FSMR3 is
not included.
The contents of the user manuals are available as help in the R&S FSMR3. The help
offers quick, context-sensitive access to the complete information for the base unit and
the firmware applications.
All user manuals are also available for download or for immediate display on the Internet.
1.3 Service manual
Describes the performance test for checking the rated specifications, module replacement and repair, firmware update, troubleshooting and fault elimination, and contains
mechanical drawings and spare part lists.
The service manual is available for registered users on the global Rohde & Schwarz
information system (GLORIS):
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1.4 Instrument security procedures
1.5 Printed safety instructions
1.6 Data sheets and brochures
Documentation overview
Application notes, application cards, white papers, etc.
Deals with security issues when working with the R&S FSMR3 in secure areas. It is
available for download on the Internet.
Provides safety information in many languages. The printed document is delivered with
the product.
The data sheet contains the technical specifications of the R&S FSMR3. It also lists the
firmware applications and their order numbers, and optional accessories.
The brochure provides an overview of the instrument and deals with the specific characteristics.
See www.rohde-schwarz.com/brochure-datasheet/FSMR3000/
1.7 Release notes and open-source acknowledgment (OSA)
The release notes list new features, improvements and known issues of the current
firmware version, and describe the firmware installation.
The open-source acknowledgment document provides verbatim license texts of the
used open source software.
See www.rohde-schwarz.com/firmware/FSMR3000/
1.8 Application notes, application cards, white papers, etc.
These documents deal with special applications or background information on particular topics.
See www.rohde-schwarz.com/application/FSMR3000/
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2 Welcome to the R&S FSMR3000 VSA
Welcome to the R&S FSMR3000 VSA application
application
The R&S FSMR3-K70 is a firmware application that adds functionality to perform vector signal analysis (VSA) to the R&S FSMR3.
The R&S FSMR3000 VSA application performs vector and scalar measurements on
digitally modulated single-carrier signals. To perform the measurements, it converts RF
signals into the complex baseband.
The R&S FSMR3000 VSA application features:
●
Flexible modulation analysis from MSK to 1024QAM
●
Numerous standard-specific default settings
●
Various graphical, numerical and statistical evaluations and result displays
●
Spectrum analyses of the measurement and error signal
●
Flexible burst search for the analysis of complex signal combinations, short bursts
or signal mix
Availability of Vector Signal Analysis
The Vector Signal Analysis application becomes available when you equip the
R&S FSMR3 with the optional Spectrum Analyzer hardware (R&S FSMR3-B1) and
firmware application R&S FSMR3-K70.
This user manual contains a description of the functionality that the application provides, including remote control operation.
General R&S FSMR3 functions
The application-independent functions for general tasks on the R&S FSMR3 are also
available for VSA measurements and are described in the R&S FSMR3 user manual.
In particular, this comprises the following functionality:
●
Data management
●
General software preferences and information
The latest version is available for download at the product homepage
Additional information
Several application notes discussing vector signal analysis using the R&S FSMR3000
VSA application are available from the Rohde & Schwarz website:
1EF93: Modulation Accuracy Measurements of DVB-S2 and DVB-S2X Signals
1EF55: EVM Measurements for ZigBee signals in the 2.4 GHz band
1MA171: How to use Rohde & Schwarz Instruments in MATLAB
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2.1 Introduction to vector signal analysis
Welcome to the R&S FSMR3000 VSA application
Introduction to vector signal analysis
Installation
You can find detailed installation instructions in the R&S FSMR3 Getting Started manual or in the Release Notes.
● Introduction to vector signal analysis...................................................................... 16
● Starting the VSA application................................................................................... 17
● Understanding the display information....................................................................17
The goal of vector signal analysis is to determine the quality of the signal that is transmitted by the device under test (DUT) by comparing it against an ideal signal. The DUT
is usually connected with the analyzer via a cable. The key task of the analyzer is to
determine the ideal signal. Hence, the analyzer aims to reconstruct the ideal signal
from the measured signal that is transmitted by the DUT. This ideal signal is commonly
referred to as the reference signal, while the signal from the DUT is called the mea-
surement signal.
After extracting the reference signal, the R&S FSMR3000 VSA application compares
the measurement signal and the reference signal, and the results of this comparison
are displayed.
Example:
The most common vector signal analysis measurement is the EVM ("Error Vector Magnitude") measurement. Here, the complex baseband reference signal is subtracted
from the complex baseband measurement signal. The magnitude of this error vector
represents the EVM value. The EVM has the advantage that it "summarizes" all potential errors and distortions in one single value. If the EVM value is low, the signal quality
of the DUT is high.
Figure 2-1: Simplified schema of vector signal analysis
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2.2 Starting the VSA application
Welcome to the R&S FSMR3000 VSA application
Understanding the display information
The VSA application adds a new application to the R&S FSMR3.
To activate the VSA application
1. Select the [MODE] key.
A dialog box opens that contains all operating modes and applications currently
available on your R&S FSMR3.
2. Select the "VSA" item.
The R&S FSMR3 opens a new measurement channel for the VSA application.
The measurement is started immediately with the default settings. It can be configured
in the VSA "Overview" dialog box, which is displayed when you select the "Overview"
softkey from any menu (see Chapter 5.1, "Configuration overview", on page 158).
Multiple Measurement Channels and Sequencer Function
When you activate an application, a new measurement channel is created which determines the measurement settings for that application. The same application can be activated with different measurement settings by creating several channels for the same
application.
The number of channels that can be configured at the same time depends on the available memory on the instrument.
Only one measurement can be performed at any time, namely the one in the currently
active channel. However, to perform the configured measurements consecutively, a
Sequencer function is provided.
If activated, the measurements configured in the currently active channels are performed one after the other in the order of the tabs. The currently active measurement is
indicated by a
are updated in the tabs (as well as the "MultiView") as the measurements are performed. Sequential operation itself is independent of the currently displayed tab.
For details on the Sequencer function, see the R&S FSMR3 User Manual.
symbol in the tab label. The result displays of the individual channels
2.3 Understanding the display information
The following figure shows a measurement diagram during analyzer operation. All different information areas are labeled. They are explained in more detail in the following
sections.
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Welcome to the R&S FSMR3000 VSA application
Understanding the display information
1
2
3
4
5
1 = Channel bar for firmware and measurement settings
2 = Window title bar with diagram-specific (trace) information
3 = Diagram area
4 = Diagram footer with diagram-specific information, depending on measurement application
5 = Instrument status bar with error messages, progress bar and date/time display
Channel bar information
In VSA application, the R&S FSMR3 shows the following settings:
Table 2-1: Information displayed in the channel bar in VSA application
Ref Level Reference level
Offset Reference level offset (if not 0)
Cap Len Capture Length (instead of result length for "Capture Buffer" display), see
"Capture Length Settings" on page 198
Std/Mod Selected measurement standard or, if no standard selected, modulation
type or loaded user-defined modulation file
Res Len Result Length
Att Mechanical and electronic RF attenuation
Freq Center frequency for the RF signal
SR Symbol Rate
Tx filter Transmit filter, see "Transmit Filter Type" on page 167
Res Rng # Number of the selected result range for burst signals, see Chapter 4.6.1,
"Result range", on page 141
Count Statistics count for averaging and other statistical operations, see "Statis-
tic Count" on page 205; cannot be edited directly
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Welcome to the R&S FSMR3000 VSA application
Understanding the display information
Input Input type of the signal source
See Chapter 5.4.1, "Input settings", on page 181
Burst Burst search active (see "Enabling Burst Searches" on page 207)
Pattern Pattern search active (see "Enabling Pattern Searches" on page 209)
Equalizer "Equalizer" active (see "State" on page 221 )
SGL The sweep is set to single sweep mode.
In addition, the channel bar also displays information on instrument settings that affect
the measurement results even though this is not immediately apparent from the display
of the measured values (e.g. transducer or trigger settings). This information is displayed only when applicable for the current measurement.
For details see the R&S FSMR3 Getting Started manual.
Window title bar information
For each diagram, the header provides the following information:
5
1 2
Figure 2-2: Window title bar information in VSA application
1 = Window name
2 = Result type
3 = Data source type
4 = Trace color
5 = Trace number
6 = Displayed signal for Meas&Ref or multi data source: "M" (Meas), "R" (Ref), "C" (Capture buffer), "E"
(Error)
7 = Trace mode
3
4
6 7
Diagram area
The diagram area displays the results according to the selected result displays (see
Chapter 3, "Measurements and result displays", on page 20).
Diagram footer information
The diagram footer (beneath the diagram) contains the start and stop symbols or time
of the evaluation range.
Status bar information
Global instrument settings, the instrument status and any irregularities are indicated in
the status bar beneath the diagram. Furthermore, the progress of the current operation
is displayed in the status bar.
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3 Measurements and result displays
3.1 Evaluation data sources in VSA
Measurements and result displays
Evaluation data sources in VSA
Various different result displays for VSA measurements are available. Which result
types are available depends on the selected data source. You can define which part of
the measured signal is to be evaluated and displayed.
The determined result and evaluation ranges are included in the result displays (where
useful) to visualize the basis of the displayed values and traces.
For background information on the result and evaluation ranges, see Chapter 4.6,
"Measurement ranges", on page 140.)
● Evaluation data sources in VSA..............................................................................20
● Result types in VSA................................................................................................ 24
● Predefined display configuration.............................................................................66
● Common parameters in VSA.................................................................................. 67
All data sources for evaluation available for VSA are displayed in the evaluation bar in
SmartGrid mode.
The data source determines which result types are available (see Table 3-1). For
details on selecting the data source for evaluation, see Chapter 6.5, "Display and win-
dow configuration", on page 246.
In diagrams in the frequency domain (Spectrum transformation, see "Result Type
Transformation" on page 247) the usable I/Q bandwidth is indicated by vertical blue
lines.
Capture Buffer...............................................................................................................21
Measurement & Reference Signal................................................................................ 21
Symbols........................................................................................................................ 22
Error Vector...................................................................................................................22
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Measurements and result displays
Evaluation data sources in VSA
Modulation Errors..........................................................................................................22
Modulation Accuracy.....................................................................................................23
Equalizer....................................................................................................................... 23
Multi Source.................................................................................................................. 24
Capture Buffer
Displays the captured I/Q data.
In "Capture Buffer" result diagrams, the result ranges are indicated by green bars along
the time axis. The currently displayed result range is indicated by a blue bar.
Figure 3-1: Result ranges for a burst signal
Note: You can use the "Capture Buffer" display to navigate through the available result
ranges (using Select Result Rng function), and analyze the individual result ranges in
separate windows.
Once the sweep has stopped, you can change the position of the result range quickly
and easily. Drag the blue bar representing the result range to a different position in the
"Capture Buffer".
The default result type is "Magnitude Absolute".
The following result types are available:
●
Chapter 3.2.21, "Magnitude absolute", on page 47
●
Chapter 3.2.22, "Magnitude overview (capture buffer)", on page 49
●
Chapter 3.2.28, "Real/imag (I/Q)", on page 55
●
Chapter 3.2.11, "Frequency absolute", on page 38
●
Chapter 3.2.34, "Vector I/Q", on page 64
Remote command:
LAY:ADD? '1',BEL,TCAP(see LAYout:ADD[:WINDow]? on page 431)
Measurement & Reference Signal
The measurement signal or the ideal reference signal (or both)
The default result type is "Magnitude Relative".
The following result types are available:
●
Chapter 3.2.21, "Magnitude absolute", on page 47
●
Chapter 3.2.23, "Magnitude relative", on page 50
●
Chapter 3.2.26, "Phase wrap", on page 53
●
Chapter 3.2.27, "Phase unwrap", on page 54
●
Chapter 3.2.11, "Frequency absolute", on page 38
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Measurements and result displays
Evaluation data sources in VSA
●
Chapter 3.2.12, "Frequency relative", on page 39
●
Chapter 3.2.28, "Real/imag (I/Q)", on page 55
●
Chapter 3.2.10, "Eye diagram real (I)", on page 37
●
Chapter 3.2.9, "Eye diagram imag (Q)", on page 35
●
Chapter 3.2.8, "Eye diagram frequency", on page 34
●
Chapter 3.2.5, "Constellation I/Q", on page 30
●
Chapter 3.2.34, "Vector I/Q", on page 64
●
Chapter 3.2.4, "Constellation frequency", on page 30
●
Chapter 3.2.33, "Vector frequency", on page 63
Remote command:
LAY:ADD? '1',BEL,REF(see LAYout:ADD[:WINDow]? on page 431)
Symbols
The detected symbols (i.e. the detected bits) displayed in a table.
The default result type is a hexadecimal symbol table.
Other formats for the symbol table are available, but no other result types (see Chap-
ter 3.2.32, "Symbol table", on page 62).
Remote command:
LAY:ADD? '1',BEL, SYMB(see LAYout:ADD[:WINDow]? on page 431)
Error Vector
The modulated difference between the complex measurement signal and the complex
reference signal:
Modulation (measurement signal - reference signal)
For example: EVM = Mag(meas - ref)
The default result type is "EVM".
The following result types are available:
●
Chapter 3.2.7, "Error vector magnitude (EVM)", on page 33
●
Chapter 3.2.28, "Real/imag (I/Q)", on page 55
●
Chapter 3.2.34, "Vector I/Q", on page 64
Remote command:
LAY:ADD? '1',BEL,EVEC(see LAYout:ADD[:WINDow]? on page 431)
Modulation Errors
The difference between the modulated complex samples in the measurement and the
modulated reference signal:
Modulation (measurement signal) - Modulation (reference signal)
For example: Magnitude Error = Mag(meas) - Mag(ref)
The default result type is "Magnitude Error".
The following result types are available:
●
Chapter 3.2.21, "Magnitude absolute", on page 47
●
Chapter 3.2.25, "Phase error", on page 52
●
Chapter 3.2.13, "Frequency error absolute", on page 40
●
Chapter 3.2.14, "Frequency error relative", on page 42
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Measurements and result displays
Evaluation data sources in VSA
Remote command:
LAY:ADD? '1',BEL,MERR(see LAYout:ADD[:WINDow]? on page 431)
Modulation Accuracy
Parameters that characterize the accuracy of modulation.
The default result type is "Result Summary".
The following result types are available:
●
Chapter 3.2.29, "Result summary", on page 56
●
Chapter 3.2.1, "Bit error rate (BER)", on page 26
The results of a "modulation accuracy" measurement can be checked for violation of
defined limits automatically. If limit check is activated and the measured values exceed
the limits, those values are indicated in red in the "Result Summary" table. If limit check
is activated and no values exceed the limits, the checked values are indicated in green.
Remote command:
LAY:ADD? '1',BEL,MACC(see LAYout:ADD[:WINDow]? on page 431)
Equalizer
Filter characteristics of the "equalizer" used to compensate for channel distortion and
parameters of the distortion itself.
The following result types are available:
●
Chapter 3.2.18, "Impulse response magnitude", on page 45
●
Chapter 3.2.19, "Impulse response phase", on page 46
●
Chapter 3.2.20, "Impulse response real/imag", on page 47
●
Chapter 3.2.16, "Frequency response magnitude", on page 44
●
Chapter 3.2.17, "Frequency response phase", on page 44
●
Chapter 3.2.15, "Frequency response group delay", on page 43
●
Chapter 3.2.3, "Channel frequency response magnitude", on page 29
●
Chapter 3.2.2, "Channel frequency response group delay", on page 28
The default result type is "Frequency Response Magnitude".
Remote command:
LAY:ADD? '1',BEL,EQU(see LAYout:ADD[:WINDow]? on page 431)
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3.2 Result types in VSA
Measurements and result displays
Result types in VSA
Multi Source
Combines two data sources in one diagram, with (initially) one trace for each data
source. This display allows you to compare the errors to the captured or measured
data directly in the diagram.
Furthermore, for carrier-in-carrier measurements, this data source makes both carriers
visible.
The default result type is "Spec (Meas+Error)".
The following result types are available:
●
Chapter 3.2.30, "Spectrum (capture buffer + error)", on page 59
●
Chapter 3.2.31, "Spectrum (measurement + error)", on page 61
Remote command:
LAY:ADD? '1',RIGH,MCOM, see LAYout:ADD[:WINDow]? on page 431
The available result types for a window depend on the selected evaluation data source.
The SCPI parameters in the following table refer to the CALC:FORM command, see
CALCulate<n>:FORMat on page 440.
Table 3-1: Available result types depending on data source
Evaluation data
source
"Capture Buffer" "Magnitude Absolute"
"Capture Buffer" "Magnitude Overview Absolute"
"Meas & Ref Signal" "Magnitude Absolute"
Result type SCPI parameter
MAGNitude
(selected capture buffer section)
"Real/Imag (I/Q)"
"Frequency Absolute"
"Vector I/Q"
(entire capture buffer)
"Magnitude Relative"
"Phase Wrap"
"Phase Unwrap"
"Frequency Absolute"
RIMag
FREQuency
COMP
MOVerview
MAGNitude
MAGNitude
PHASe
UPHase
FREQuency
"Frequency Relative"
"Real/Imag (I/Q)"
"Eye Diagram Real (I)"
"Eye Diagram Imag (Q)"
FREQuency
RIMag
IEYE
QEYE
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Measurements and result displays
Result types in VSA
Evaluation data
source
"Symbols" "Binary" -
"Error Vector" "EVM"
"Modulation Errors" "Magnitude Error"
Result type SCPI parameter
"Eye Diagram Frequency"
"Constellation I/Q"
"Constellation I/Q (Rotated)"
"Vector I/Q"
"Constellation Frequency"
"Vector Frequency"
"Octal" -
"Decimal" -
"Hexadecimal" -
"Real/Imag (I/Q)"
"Vector I/Q"
"Phase Error"
FEYE
CONS
RCON
COMP
CONF
COVF
MAGNitude
RIMag
COMP
MAGNitude
PHASe
"Frequency Error Absolute"
"Frequency Error Relative"
"Modulation Accuracy"
"Equalizer" "Impulse Response Magnitude"
"Multi Source" "Spectrum (Real/Imag) (Capture buf-
"Bit Error Rate"
"Result Summary"
"Impulse Response Phase"
"Impulse Response Real/Imag"
"Frequency Response Magnitude"
"Frequency Response Phase"
"Frequency Response Group Delay"
"Channel Frequency Response Magnitude"
"Channel Frequency Response
Group Delay"
fer + Error)"
"Spectrum (Real/Imag) (Measurement
+ Error)"
FREQuency
FREQuency
BERate
RSUM
MAGNitude
UPHase
RIMag
MAGNitude
UPHase
GDELay
MAGNitude
GDELay
RIMag (query only)
RIMag (query only)
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Measurements and result displays
Result types in VSA
For details on selecting the data source and result types for evaluation, see Chap-
ter 6.5, "Display and window configuration", on page 246.
Remote command:
CALCulate<n>:FORMat on page 440
● Bit error rate (BER)................................................................................................. 26
● Channel frequency response group delay.............................................................. 28
● Channel frequency response magnitude................................................................ 29
● Constellation frequency...........................................................................................30
● Constellation I/Q......................................................................................................30
● Constellation I/Q (rotated).......................................................................................32
● Error vector magnitude (EVM)................................................................................ 33
● Eye diagram frequency........................................................................................... 34
● Eye diagram imag (Q).............................................................................................35
● Eye diagram real (I).................................................................................................37
● Frequency absolute.................................................................................................38
● Frequency relative...................................................................................................39
● Frequency error absolute........................................................................................40
● Frequency error relative..........................................................................................42
● Frequency response group delay............................................................................43
● Frequency response magnitude..............................................................................44
● Frequency response phase.....................................................................................44
● Impulse response magnitude..................................................................................45
● Impulse response phase.........................................................................................46
● Impulse response real/imag....................................................................................47
● Magnitude absolute.................................................................................................47
● Magnitude overview (capture buffer).......................................................................49
● Magnitude relative...................................................................................................50
● Magnitude error.......................................................................................................51
● Phase error............................................................................................................. 52
● Phase wrap............................................................................................................. 53
● Phase unwrap......................................................................................................... 54
● Real/imag (I/Q)........................................................................................................55
● Result summary...................................................................................................... 56
● Spectrum (capture buffer + error)........................................................................... 59
● Spectrum (measurement + error)............................................................................61
● Symbol table........................................................................................................... 62
● Vector frequency.....................................................................................................63
● Vector I/Q................................................................................................................64
3.2.1 Bit error rate (BER)
A bit error rate (BER) measurement compares the transmitted bits with the determined
symbol decision bits:
BER = error bits / number of analyzed bits
As a prerequisite for this measurement, the VSA application must know which bit
sequences are correct, i.e. which bit sequences can occur. This knowledge must be
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Measurements and result displays
Result types in VSA
provided as a list of possible data sequences in xml format, which is loaded in the VSA
application (see Chapter 4.9, "Known data files - dependencies and restrictions",
on page 148).
Auxiliary tool to create known data files
An auxiliary tool to create known data files from data that is already available in the
R&S FSMR3000 VSA application is provided with the instrument free of charge.
See Chapter 8.2.4.2, "How to create known data files", on page 262.
Alternatively, for data generated by a pseudo-random bit sequence (PRBS) generator,
you can specify the algorithm used to generate the data, so the R&S FSMR3000 VSA
application knows which sequences can occur. This function requires the R&S FSMR3K70P option. See Chapter 4.10, "Known data from PRBS generators", on page 149.
If known data is specified in the application, the BER result display is available for the
following source types:
●
"Modulation Accuracy"
Note that this measurement can take some time, as each symbol decision must be
compared to the possible data sequences one by one.
The BER measurement is an indicator for the quality of the demodulated signal. High
BER values indicate problems such as:
●
Inadequate demodulation settings
●
Poor quality in the source data
●
False or missing sequences in the known data file
●
Result range alignment leads to a mismatch of the input data with the defined
sequences
A BER value of 0.5 means that for at least one measurement no matching sequence
was found.
See also Chapter 4.4.3, "Demodulation and symbol decisions", on page 116 and the
application sheet R&S®FSW-K70 Measuring the BER and the EVM for Signals with
Low SNR on the Rohde & Schwarz Internet site.
The following information is provided in the "Bit Error Rate" result display:
●
"Bit Error Rate": error bits / number of analyzed bits
●
"Total # of Errors": number of detected bit errors (known data compared to symbol
decisions)
●
"Total # of Bits": number of analyzed bits
For each of these results, the following values are provided:
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Measurements and result displays
Result types in VSA
BER result Description
Current Value for current result range
Minimum Minimum "Current" value during the current measurement
Maximum Maximum "Current" value during the current measurement
Accumulative Total value over several measurements;
For BER: "Total # of Errors" / "Total # of Bits" (similar to average function)
Remote commands:
LAY:ADD? '1',BEL,MACC
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FORM BER
To define the result type (see CALCulate<n>:FORMat on page 440).
CALC:BER?
To query the results (see CALCulate<n>:BERate? on page 459).
3.2.2 Channel frequency response group delay
The frequency response group delay of the channel is the derivation of phase over frequency for the original input signal. It is a measure of phase distortion.
Remote commands:
LAY:ADD? '1',BEL,EQU
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FEED 'XFR:DDEM:IRAT'
To define the channel frequency response result type (see CALCulate<n>:FEED
on page 439).
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3.2.3 Channel frequency response magnitude
Measurements and result displays
Result types in VSA
CALC:FORM GDEL
To define the group delay result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.6, "Equalizer", on page 453).
The frequency response magnitude of the channel indicates which distortions occurred
during transmission of the input signal. It is only determined if the equalizer is activated.
The bandwidth for which the channel transfer function can be estimated is not only limited by the usable I/Q bandwidth, but also by the bandwidth of the analyzed input signal. Areas with low reception power, e.g. at the filter edges, can suffer from less accurate estimation results.
Remote commands:
LAY:ADD? '1',BEL,EQU
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FEED 'XFR:DDEM:IRAT'
To define the channel frequency response result type (see CALCulate<n>:FEED
on page 439).
CALC:FORM MAGN
To define the magnitude result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.6, "Equalizer", on page 453).
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3.2.4 Constellation frequency
Measurements and result displays
Result types in VSA
Depending on the modulation type,, the source signal (without inter-symbol interference) as an X/Y plot; only the symbol decision instants are drawn and not connected.
Available for source types:
●
"Meas & Ref Signal"
Figure 3-2: Constellation Frequency result display
A special density trace mode is available for this diagram. The occurrence of each
value within the current result range or evaluation range is indicated by color.
Remote commands:
LAY:ADD? '1',BEL,MEAS
To define the required source type (see LAYout:ADD[:WINDow]? on page 431)
CALC:FORM CONF
To define the result type (see CALCulate<n>:FORMat on page 440)
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.3, "Polar diagrams", on page 452)
3.2.5 Constellation I/Q
The complex source signal (without inter-symbol interference) as an X/Y plot; only the
(de-rotated) symbol decision instants are drawn and not connected
Available for source types:
●
"Meas & Ref Signal"
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Result types in VSA
Figure 3-3: Constellation I/Q diagram for QPSK modulated signal
Markers in the Constellation diagram
Using markers you can detect individual constellation points for a specific symbol.
When you activate a marker in the Constellation diagram, its position is defined by the
symbol the point belongs to. However, the marker result indicates the I and Q values of
the point.
Constellation for subframe or symbol types in multi-modulation signals
For signals with a user-defined frame structure (see Chapter 4.11, "Multi-modulation
analysis (R&S FSMR3-K70M)", on page 151), the constellation diagram displays all
symbols in the entire frame by default. However, if you restrict the evaluation range to
the symbols of a particular subframe, only those constellation points are displayed (see
Chapter 5.10, "Evaluation range configuration", on page 227).
Density trace
A special density trace mode is available for this diagram. The occurrence of each
value within the current result range or evaluation range is indicated by color.
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Result types in VSA
Figure 3-4: Example for a density constellation trace
Remote commands:
LAY:ADD? '1',BEL,MEAS
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FORM CONS
To define the result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.3, "Polar diagrams", on page 452).
CALCulate<n>:MARKer<m>:Y? on page 410
To query the marker I/Q values.
3.2.6 Constellation I/Q (rotated)
The complex source signal as an X/Y plot. As opposed to the common "Constellation
I/Q" display, the symbol decision instants, including the rotated ones, are drawn and
not connected.
Available for source types:
●
"Meas & Ref Signal"
This result type is only available for signals with a rotating modulation.
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C
tEV
tEVM
k
TkREF
K
C
2
1
periods symbol ofduration T
Measurements and result displays
Result types in VSA
Figure 3-5: Constellation I/Q (Rotated) result display vs. common Constellation I/Q for 3π/8-8PSK
A special density trace mode is available for this diagram. The occurrence of each
value within the current result range or evaluation range is indicated by color.
Remote commands:
LAY:ADD? '1',BEL,MEAS
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FORM RCON
To define the result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.3, "Polar diagrams", on page 452).
modulation
3.2.7 Error vector magnitude (EVM)
Displays the error vector magnitude as a function of symbols or time.
with t=n·TD and TD=the duration of one sampling period at the sample rate defined by
the display points per symbol parameter (see "Display Points/Sym" on page 248).
The normalization constant C is chosen according to the EVM normalization. By
default C² is the mean power of the reference signal.
and
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Result types in VSA
Note that k=0.5·n·T for Offset QPSK with inactive Offset EVM.
Figure 3-6: Error Vector Magnitude result display
For signals with a user-defined frame structure (see Chapter 4.11, "Multi-modulation
analysis (R&S FSMR3-K70M)", on page 151), the individual subframes are indicated
by vertical green lines.
Available for source types:
●
"Error Vector"
Remote commands:
LAY:ADD? '1',BEL,EVEC
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FORM MAGN
To define the result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.2, "Cartesian diagrams", on page 451).
3.2.8 Eye diagram frequency
The eye diagram of the currently measured frequencies and/or the reference signal.
The time span of the data depends on the evaluation range (capture buffer).
Available for source types:
●
"Meas & Ref Signal"
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Display lines are available in eye diagrams which allow you to determine the size of the
eye, see also Chapter 8.3.2, "How to measure the size of an eye", on page 269.
A special density trace mode is available for this diagram. The occurrence of each
value within the current result range or evaluation range is indicated by color.
Figure 3-7: Eye Diagram Frequency result display with density trace
Remote commands:
LAY:ADD? '1',BEL,MEAS
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FORM FEYE
To define the result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.2, "Cartesian diagrams", on page 451).
3.2.9 Eye diagram imag (Q)
The eye pattern of the quadrature (Q) channel; the x-axis range is from -1 to +1 symbols (MSK: -2 to +2)
Available for source types:
●
"Meas & Ref Signal"
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Figure 3-8: Eye Diagram Imag (Q) result display
Display lines are available in eye diagrams which allow you to determine the size of the
eye, see also Chapter 8.3.2, "How to measure the size of an eye", on page 269.
A special density trace mode is available for this diagram. The occurrence of each
value within the current result range or evaluation range is indicated by color.
Figure 3-9: Eye Diagram Imag (Q) result display with density trace
Remote commands:
LAY:ADD? '1',BEL,MEAS
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FORM QEYE
To define the result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
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3.2.10 Eye diagram real (I)
Measurements and result displays
Result types in VSA
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.2, "Cartesian diagrams", on page 451).
The eye pattern of the inphase (I) channel; the x-axis value range is from -1 to +1 symbols (MSK: -2 to +2)
Available for source types:
●
"Meas & Ref Signal"
Figure 3-10: Eye Diagram Real (I) result display
Display lines are available in eye diagrams which allow you to determine the size of the
eye, see also Chapter 8.3.2, "How to measure the size of an eye", on page 269.
A special density trace mode is available for this diagram. The occurrence of each
value within the current result range or evaluation range is indicated by color.
Remote commands:
LAY:ADD? '1',BEL,MEAS
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FORM IEYE
To define the result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.2, "Cartesian diagrams", on page 451).
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tMEAS
dt
d
tFREQ
MEAS
2
1
tCapt
dt
d
tFREQ
CAPT
2
1
.
3.2.11 Frequency absolute
Measurements and result displays
Result types in VSA
The instantaneous frequency of the signal source; the absolute value is displayed in
Hz.
Available for source types:
●
"Meas & Ref Signal"
●
"Capture Buffer"
Figure 3-11: Frequency Absolute result display
Meas&Ref signal:
with t=n·TD and TD=the duration of one sampling period at the sample rate defined by
the display points per symbol parameter (see "Display Points/Sym" on page 248).
For signals with a user-defined frame structure (see Chapter 4.11, "Multi-modulation
analysis (R&S FSMR3-K70M)", on page 151), and based on the "Meas and Ref" sig-
nal, the individual subframes are indicated by vertical green lines.
Capture buffer:
When evaluating the capture buffer, the absolute frequency is derived from the measured phase, with TD=the duration of one sampling period at the sample rate (see
"Sample Rate" on page 199).
Note that this result display is based on an individual capture buffer range. If more than
256 000 samples are captured, overlapping ranges with a size of 256 000 each are
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tMEAS
dt
d
tFREQ
MEAS
2
1
Measurements and result displays
Result types in VSA
created. Only one range at a time can be displayed in the "Frequency Absolute" result
display. For details see Chapter 4.8, "Capture buffer display", on page 146.
This measurement is mainly of interest when using the MSK or FSK modulation, but
can also be used for the PSK/QAM modulations. However, since these modulations
can have transitions through zero in the I/Q plane, in this case, possibly you notice
uncritical spikes. The reason is that the phase of zero (or a complex value close to
zero) is of limited significance, but still influences the result of the instantaneous frequency measurement.
Remote commands:
LAY:ADD? '1',BEL,MEAS
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FORM FREQ
To define the result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.1, "Capture buffer results", on page 451/Chapter 11.9.2.2, "Cartesian diagrams", on page 451).
3.2.12 Frequency relative
The instantaneous frequency of the signal source.
The results are normalized to the symbol rate (PSK and QAM modulated signals), the
estimated FSK deviation (FSK modulated signals) or one quarter of the symbol rate
(MSK modulated signals).
with t=n·TD and TD=the duration of one sampling period at the sample rate defined by
the display points per symbol parameter (see "Display Points/Sym" on page 248).
This measurement is mainly of interest when using the MSK or FSK modulation, but
can also be used for the PSK/QAM modulations. See also the note for Chapter 3.2.11,
"Frequency absolute", on page 38.
Available for source types:
●
"Meas & Ref Signal"
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tFREQtFREQtERRFREQ
REFMEAS
_
Measurements and result displays
Result types in VSA
Figure 3-12: Frequency Relative result display
For signals with a user-defined frame structure (see Chapter 4.11, "Multi-modulation
analysis (R&S FSMR3-K70M)", on page 151), the individual subframes are indicated
by vertical green lines.
Remote commands:
LAY:ADD? '1',BEL,MEAS
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FORM FREQ
To define the result type (see CALCulate<n>:FORMat on page 440).
DISP:TRAC:Y:MODE REL
To define relative values (see DISPlay[:WINDow<n>][:SUBWindow<w>]:
TRACe<t>:Y[:SCALe]:MODE on page 444).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.2, "Cartesian diagrams", on page 451).
3.2.13 Frequency error absolute
Displays the error of the instantaneous frequency in Hz of the measurement signal with
respect to the reference signal as a function of symbols over time.
with t=n·TD and TD=the duration of one sampling period at the sample rate defined by
the display points per symbol parameter (see "Display Points/Sym" on page 248).
Note that this measurement does not consider a possible carrier frequency offset. It
has already been compensated for in the measurement signal.
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Measurements and result displays
Result types in VSA
This measurement is mainly of interest when using the MSK or FSK modulation, but
can also be used for the PSK/QAM modulations. However, since these modulations
can have transitions through zero in the I/Q plane, in this case, you possibly notice
uncritical spikes. The reason is that the phase of zero (or a complex value close to
zero) has in fact limited significance, but still influences the result of the current frequency measurement.
Figure 3-13: Frequency Error Absolute result display
Available for source types:
●
"Modulation Errors"
For signals with a user-defined frame structure (see Chapter 4.11, "Multi-modulation
analysis (R&S FSMR3-K70M)", on page 151), the individual subframes are indicated
by vertical green lines.
Remote commands:
LAY:ADD? '1',BEL,MERR
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FORM FREQ
To define the result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.2, "Cartesian diagrams", on page 451).
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tFREQtFREQtERRFREQ
REFMEAS
_
3.2.14 Frequency error relative
Measurements and result displays
Result types in VSA
Displays the error of the instantaneous frequency of the measurement signal with
respect to the reference signal as a function of symbols over time.
The results are normalized to the symbol rate (PSK and QAM modulated signals), the
estimated FSK deviation (FSK modulated signals) or one quarter of the symbol rate
(MSK modulated signals).
with t=n·TD and TD=the duration of one sampling period at the sample rate defined by
the display points per symbol parameter (see "Display Points/Sym" on page 248).
This measurement is mainly of interest when using the MSK or FSK modulation, but
can also be used for the PSK/QAM modulations. See also the note for Chapter 3.2.13,
"Frequency error absolute", on page 40.
Figure 3-14: Frequency Error Relative result display
Available for source types:
●
"Modulation Errors"
For signals with a user-defined frame structure (see Chapter 4.11, "Multi-modulation
analysis (R&S FSMR3-K70M)", on page 151), the individual subframes are indicated
by vertical green lines.
Remote commands:
LAY:ADD? '1',BEL,MERR
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FORM FREQ
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3.2.15 Frequency response group delay
Measurements and result displays
Result types in VSA
To define the result type (see CALCulate<n>:FORMat on page 440).
DISP:TRAC:Y:MODE REL
To define relative values (see DISPlay[:WINDow<n>][:SUBWindow<w>]:
TRACe<t>:Y[:SCALe]:MODE on page 444).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.2, "Cartesian diagrams", on page 451).
The Frequency Response Group Delay of the "equalizer" is the derivation of phase
over frequency. It is a measure of phase distortion.
Available for source types:
●
"Equalizer"
Remote commands:
LAY:ADD? '1',BEL,EQU
To define the required source type (see LAYout:ADD[:WINDow]? on page 431)
CALC:FEED 'XFR:DDEM:RAT'
To define the frequency response result type (see CALCulate<n>:FEED
on page 439).
CALC:FORM GDEL
To define the group delay result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.6, "Equalizer", on page 453).
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3.2.16 Frequency response magnitude
Measurements and result displays
Result types in VSA
Magnitude of the frequency response of the current equalizer. Note that the frequency
response of the equalizer is not a pure inverted function of the channel response, as
both functions are calculated independently. The frequency response is calculated by
determining an optimal EVM for the input signal.
Available for source types:
●
"Equalizer"
Remote commands:
LAY:ADD? '1',BEL,EQU
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FEED 'XFR:DDEM:RAT'
To define the frequency response result type (see CALCulate<n>:FEED
on page 439).
CALC:FORM MAGN
To define the magnitude result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.6, "Equalizer", on page 453).
3.2.17 Frequency response phase
Phase of the frequency response of the current "equalizer".
Available for source types:
●
"Equalizer"
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3.2.18 Impulse response magnitude
Measurements and result displays
Result types in VSA
Remote commands:
LAY:ADD? '1',BEL,EQU
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FEED 'XFR:DDEM:RAT'
To define the frequency response result type (see CALCulate<n>:FEED
on page 439).
CALC:FORM UPH
To define the unwrapped phase result type (see CALCulate<n>:FORMat
on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.6, "Equalizer", on page 453).
The "Impulse Response Magnitude" shows the magnitude of the equalizer filter in the
time domain.
Available for source types:
●
"Equalizer"
Remote commands:
LAY:ADD? '1',BEL,EQU
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FEED 'XTIM:DDEM:IMP'
To define the "Impulse Response" result type (see CALCulate<n>:FEED
on page 439).
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3.2.19 Impulse response phase
Measurements and result displays
Result types in VSA
CALC:FORM MAGN
To define the "Magnitude" result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.6, "Equalizer", on page 453).
The "Impulse Response Phase" shows the phase of the equalizer coefficients in the
time domain.
Available for source types:
●
"Equalizer"
Remote commands:
LAY:ADD? '1',BEL,EQU
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FEED 'XTIM:DDEM:IMP'
To define the "Impulse Response" result type (see CALCulate<n>:FEED
on page 439).
CALC:FORM UPH
To define the "Phase" result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
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3.2.20 Impulse response real/imag
Measurements and result displays
Result types in VSA
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.6, "Equalizer", on page 453).
The "Real/Imag" diagram of the impulse response is a stem diagram. It displays the filter characteristics in the time domain for both the I and the Q branches individually.
Using this information the equalizer is uniquely characterized and can be recreated by
other applications.
Available for source types:
●
"Equalizer"
Remote commands:
LAY:ADD? '1',BEL,EQU
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FEED 'XTIM:DDEM:IMP'
To define the impulse response result type (see CALCulate<n>:FEED on page 439).
CALC:FORM RIM
To define the real/imag result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.6, "Equalizer", on page 453).
3.2.21 Magnitude absolute
Source type Capture Buffer:
"Magnitude absolute", that is: the actual signal amplitude, of the captured signal in the
capture buffer.
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tMEAStMag
MEAS
Measurements and result displays
Result types in VSA
Figure 3-15: Magnitude Absolute result display for capture buffer data
For capture buffers containing more than 256,000 samples, the magnitude for a section of the capture buffer (max. 256 000 samples) is displayed. The section is selected
such that it surrounds the currently selected result range. The currently displayed section is indicated in the Magnitude overview (capture buffer) using vertical blue lines.
To display the entire capture buffer with all sections in one diagram, use the Magnitude
overview (capture buffer) result display.
Note that trace modes that calculate results for several sweeps (Average, MinHold,
MaxHold) are not available for the "Magnitude absolute" result display.
For more information on the capture buffer see Chapter 4.8, "Capture buffer display",
on page 146.
Source type Meas & Ref Signal:
The actual signal amplitude is displayed:
with t = n·TD and
TD = the duration of one sampling period at the defined sample rate defined by the display points per symbol parameter (see "Display Points/Sym" on page 248)
For signals with a user-defined frame structure (see Chapter 4.11, "Multi-modulation
analysis (R&S FSMR3-K70M)", on page 151), and based on the "Meas and Ref" sig-
nal, the individual subframes are indicated by vertical green lines.
Remote commands:
LAY:ADD? '1',BEL,CBUF
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
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tMEAStMag
MEAS
3.2.22 Magnitude overview (capture buffer)
Measurements and result displays
Result types in VSA
CALC:FORM MAGN
To define the result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.1, "Capture buffer results", on page 451).
To query the start of the result range:
[SENSe:]DDEMod:SEARch:MBURst:STARt[:SYMBols]? on page 457
[SENSe:]DDEMod:SEARch:MBURst:STARt:SAMPles? on page 457
Magnitude of the source signal in the entire capture buffer; the actual signal amplitude
is displayed:
with t=n·TD and
TD=the duration of one sampling period at the sample rate defined by the display points
per symbol parameter (see "Display Points/Sym" on page 248)
Note that for very large numbers of samples (>25 000), the samples are mapped to
25 000 trace points using an autopeak detector for display. Thus, this result display is
not suitable to detect transient effects or analyze individual symbols closely. For these
purposes, use the Magnitude absolute result display instead.
The "Magnitude Overview (Capture Buffer)" is only available for the source type:
●
"Capture Buffer"
Figure 3-16: Magnitude Overview (Capture Buffer) result display
For more information on the capture buffer, see Chapter 4.8, "Capture buffer display",
on page 146.
Restrictions
Note the following restrictions that apply to this result display:
●
Only one trace is available
●
Only the trace modes "Clear/Write" and "View" are available.
See also Chapter 6.1, "Trace settings", on page 232.
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3.2.23 Magnitude relative
Measurements and result displays
Result types in VSA
Remote commands:
LAY:ADD? '1',BEL,CBUF
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FORM MOV
To define the result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.1, "Capture buffer results", on page 451).
Magnitude of the source signal; the signal amplitude is scaled to the ideal reference
signal
Available for source types:
●
"Meas & Ref Signal"
Figure 3-17: Magnitude Relative result display
For signals with a user-defined frame structure (see Chapter 4.11, "Multi-modulation
analysis (R&S FSMR3-K70M)", on page 151), and based on the "Meas and Ref" sig-
nal, the individual subframes are indicated by vertical green lines.
Remote commands:
LAY:ADD? '1',BEL,MEAS
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FORM MAGN
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tMAGtMAGtERRMAG
REFMEAS
_
3.2.24 Magnitude error
Measurements and result displays
Result types in VSA
To define the result type (see CALCulate<n>:FORMat on page 440).
DISP:TRAC:Y:MODE REL
To define relative values (see DISPlay[:WINDow<n>][:SUBWindow<w>]:
TRACe<t>:Y[:SCALe]:MODE on page 444).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.2, "Cartesian diagrams", on page 451).
Displays the magnitude error of the measurement signal with respect to the reference
signal (as a function of symbols over time)
with t=n·TD and TD=the duration of one sampling period at the sample rate defined by
the display points per symbol parameter (see "Display Points/Sym" on page 248).
Figure 3-18: Magnitude Error result display
Available for source types:
●
"Modulation Errors"
For signals with a user-defined frame structure (see Chapter 4.11, "Multi-modulation
analysis (R&S FSMR3-K70M)", on page 151), the individual subframes are indicated
by vertical green lines.
Remote commands:
LAY:ADD? '1',BEL,MERR
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tPHASEtPHASEtERRPHASE
REFMEAS
_
3.2.25 Phase error
Measurements and result displays
Result types in VSA
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FORM MAGN
To define the result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.2, "Cartesian diagrams", on page 451).
Displays the phase error of the measurement signal with respect to the reference signal as a function of symbols over time.
with t=n·TD and TD=the duration of one sampling period at the sample rate defined by
the display points per symbol parameter (see "Display Points/Sym" on page 248).
Figure 3-19: Phase Error result display
Available for source types:
●
"Modulation Errors"
For signals with a user-defined frame structure (see Chapter 4.11, "Multi-modulation
analysis (R&S FSMR3-K70M)", on page 151), the individual subframes are indicated
by vertical green lines.
Remote commands:
LAY:ADD? '1',BEL,MERR
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
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tMEAStPhase
MEAS
3.2.26 Phase wrap
Measurements and result displays
Result types in VSA
CALC:FORM PHAS
To define the result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.2, "Cartesian diagrams", on page 451).
The phase or argument of the signal; the display is limited to the phase value range of
[-180°, 180°]
with t=n·TD and TD=the duration of one sampling period at the sample rate defined by
the display points per symbol parameter (see "Display Points/Sym" on page 248).
Available for source types:
●
"Meas & Ref Signal"
Figure 3-20: Phase Wrap result display
For signals with a user-defined frame structure (see Chapter 4.11, "Multi-modulation
analysis (R&S FSMR3-K70M)", on page 151), the individual subframes are indicated
by vertical green lines.
Remote commands:
LAY:ADD? '1',BEL,REF
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FORM PHASe
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3.2.27 Phase unwrap
Measurements and result displays
Result types in VSA
To define the result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.2, "Cartesian diagrams", on page 451).
The phase of the signal; the display is not limited to [-180°, 180°].
Available for source types:
●
"Meas & Ref Signal"
Figure 3-21: Phase Unwrap result display
For signals with a user-defined frame structure (see Chapter 4.11, "Multi-modulation
analysis (R&S FSMR3-K70M)", on page 151), the individual subframes are indicated
by vertical green lines.
Remote commands:
LAY:ADD? '1',BEL,MEAS
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FORM UPHase
To define the result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.2, "Cartesian diagrams", on page 451).
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3.2.28 Real/imag (I/Q)
Measurements and result displays
Result types in VSA
Real and imaginary part of the measurement or reference signal in separate measurement diagrams; the x-axis (scaled in time units or symbols) is identical for both diagrams.
Available for source types:
●
"Capture Buffer"
●
"Meas & Ref Signal"
●
"Error Vector"
Figure 3-22: Real/Imag (I/Q) result display
Capture buffer display
Note that this result display is based on an individual capture buffer range. If more than
256 000 samples are captured, overlapping ranges with a size of 256 000 each are
created. Only one range at a time can be displayed in the "Real/Imag" result display.
For details see Chapter 4.8, "Capture buffer display", on page 146.
The scaling of the capture buffer depends on the input source:
●
Scaling is relative to the current reference level for RF input.
●
Scaling is relative to the full scale level for I/Q input.
Remote commands:
LAY:ADD? '1',BEL,MEAS
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FORM RIMag
To define the result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.2, "Cartesian diagrams", on page 451).
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3.2.29 Result summary
Measurements and result displays
Result types in VSA
The "Modulation Accuracy" results in a table. For details on the parameters see Chap-
ter 3.4, "Common parameters in VSA", on page 67.
"Freezing" the displayed values
You can freeze the contents of the "Result Summary" after a measurement to maintain
the values on the display, while the measurement continues or is restarted. As for
graphical displays, set the Trace Mode for the "Result Summary" to "View". The table is
no longer updated. The "View" trace mode is indicated in the window title. To update
the "Result Summary" as usual, set the trace mode back to "Clear Write".
Basis of evaluation
Most values that are displayed in the "Result Summary" are calculated over the "Evaluation Range" (see Chapter 5.10, "Evaluation range configuration", on page 227). They
are evaluated according to the setting of the Display Points/Sym parameter. For example, if "Display Points/Symbol" is "1", only the symbol instants contribute to the result
displayed in the "Result Summary".
Table 3-2: Results calculated over the evaluation range
PSK, MSK, QAM FSK
"EVM" "Frequency Error"
"MER" "Magnitude Error"
"Phase Error" "Power"
"Magnitude Error"
"Rho"
"Power"
The following results that are based on internal estimation algorithms (see Chapter 4.5,
"Signal model, estimation and modulation errors", on page 123) are calculated over the
"Estimation range" (see also Chapter 4.5.1.2, "Estimation", on page 125).
Table 3-3: Results calculated over the estimation range
PSK, MSK, QAM FSK
"Carrier Frequency Error" "FSK Deviation Error"
"Symbol Rate Error"
"I/Q Skew"
"I/Q Offset" "FSK Measurement Deviation"
"I/Q Imbalance" "Carrier Frequency Error"
"Gain Imbalance" "Carrier Frequency Drift"
"Quadrature Error"
"Amplitude Droop"
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Measurements and result displays
Result types in VSA
Current value
In the "Current" column, the value evaluation for the current evaluation is displayed.
For example, the "EVM Peak" value in the current sweep corresponds to the peak of
the trace values within the evaluation range for the current sweep (as indicated by
marker 1 in Figure 3-23).
Figure 3-23: Example for Result Summary with current EVM peak value marked
If you want to compare the trace values to the results of the "Result Summary", make
sure to match the displayed points per symbol of the trace and of the "Result Summary". Refer to "Display Points/Sym" on page 248 for details.
Mean value
In the "Mean" column, the linear mean of the values that are in the "Current" column is
displayed. Note that if the values are in a logarithmic representation, e.g. the I/Q Offset, the linear values are averaged.
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Measurements and result displays
Result types in VSA
Peak value
In the "Peak" column, the maximum value that occurred during several evaluations is
displayed. Note that when the value can be positive and negative, e.g. the phase error,
the maximum absolute value (maintaining its sign) is displayed. The peak value of
"Rho" is handled differently, since its minimum value represents the worst case. In that
case, the minimum value is displayed.
Standard Deviation
The value for the standard deviation is calculated on the linear values and then converted to the displayed unit.
95-percentile
The 95-percentile value is based on the distribution of the current values. Since the
phase error and the magnitude error can usually be assumed to be distributed around
zero, the 95-Percentile for these values is calculated based on their absolute values.
Again, the "Rho" value is handled differently. Here, the 5-Percentile is displayed, since
the lowest rho value represents the worst case.
Remote commands:
LAY:ADD? '1',BEL, MACC
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FORM RSUM
To define the result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA] on page 449 and Chapter 11.9.2.5,
"Result summary", on page 452).
CALC:MARK:FUNC:DDEM:STAT:<parameter>
To query individual parameter values (see Chapter 11.9.4, "Retrieving parameter val-
ues", on page 458.
Result Summary - Individual Results
The "Result Summary" can display either all or only a single modulation accuracy
parameter. Only the most important parameters can be displayed individually, namely
the parameters for which modulation accuracy limits can be defined (see "Limit Value"
on page 245).
To select individual results for display, tap the "Result Summary" table header (only
once - a double-tap maximizes the "Result Summary" window). A "Table Configuration"
dialog box is displayed in which you can select the parameter to be displayed.
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Measurements and result displays
Result types in VSA
By default, all parameters are displayed. If you select a specific parameter, the "Result
Summary" display is replaced by the individual result display.
Figure 3-24: Result display for individual value in Result Summary
In addition to the current measurement value, the statistical results (see Chap-
ter 3.2.29, "Result summary", on page 56) and the peak limit value (see "Limit Value"
on page 245) for the selected parameter are displayed.
For details on the displayed results, see Chapter 3.4, "Common parameters in VSA",
on page 67.
Remote command:
DISPlay[:WINDow<n>]:ITEM[:LINE][:VALue] on page 442
3.2.30 Spectrum (capture buffer + error)
This display combines two diagrams in one. The first trace displays the spectrum of the
real/imaginary data in the capture buffer. The second trace displays the spectrum of
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Result types in VSA
the real/imaginary data of the error. Optionally, the data source of the traces can be
switched. Which source is currently displayed for which trace is indicated in the window
title bar.
Carrier-in-carrier signals
For carrier-in-carrier measurements, this result display makes both carriers visible. The
following example shows two superimposed QPSK signals: one with a symbol rate of
10 MHz (the analyzed signal, yellow), one with a symbol rate of 3 MHz, whose spectrum becomes visible in the error trace (blue).
Figure 3-25: Example of a carrier-in-carrier signal in a multi source result display.
Similarly, the "Spectrum (Measurement + Error)" result display can be used to reveal
carrier-in-carrier signals.
Remote commands:
LAY:ADD? '1',BEL,MCOM
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FEED 'XTIM:DDEM:TCAP:ERR'
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3.2.31 Spectrum (measurement + error)
Measurements and result displays
Result types in VSA
To define the result type (see CALCulate<n>:FEED on page 439).
CALC:TRAC TCAP; CALC:TRAC2 ERR
To define trace1 to be based on the capture buffer data and trace 2 on the error
(default, see CALCulate<n>:TRACe<t>[:VALue] on page 404).
TRAC:DATA? TRACE1
To query the trace results for capture buffer data (see TRACe<n>[:DATA]?
TRACE<n> and Chapter 11.9.2.4, "Symbols", on page 452).
TRAC:DATA? TRACE2
To query the trace results for error data.
This display combines two diagrams in one. The first trace displays the spectrum of the
real/imaginary data from the measured signal. The second trace displays the spectrum
of the real/imaginary data of the error. Optionally, the data source of the traces can be
switched. Which source is currently displayed for which trace is indicated in the window
title bar.
Remote commands:
LAY:ADD? '1',BEL,MCOM
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FEED 'XTIM:DDEM:MEAS:ERR'
To define the result type (see CALCulate<n>:FEED on page 439).
CALC:TRAC MEAS; CALC:TRAC2 ERR
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3.2.32 Symbol table
Measurements and result displays
Result types in VSA
To define trace1 to be based on the measurement data and trace 2 on the error
(default, see CALCulate<n>:TRACe<t>[:VALue] on page 404).
TRAC:DATA? TRACE1
To query the trace results for measurement data (see TRACe<n>[:DATA]?
TRACE<n> and Chapter 11.9.2.4, "Symbols", on page 452).
TRAC:DATA? TRACE2
To query the trace results for error data.
Symbol numbers are displayed as a table. Each symbol is represented by an entry in
the table. The symbols can be displayed in binary, octal, hexadecimal or decimal format. Selected symbols (using markers) are highlighted by a blue frame.
Example:
Figure 3-26: Symbols result display in hexadecimal mode
The evaluation range is indicated by red brackets.
If a pattern search is active, a found pattern is indicated by a green background in the
symbol table. If, during demodulation, individual symbols do not match the pattern after
all, these symbols are indicated by red values.
If known data is loaded as a reference, symbols which do not match this data are also
indicated by red values.
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Figure 3-27: Symbol errors in the symbol table
Tip: If you assume that a signal has a pattern, but do not know it in advance, you can
identify it using the symbol table. Measure the signal and check for a pattern in the
symbol table. Then you can copy the symbols from the symbol table to the pattern definition for subsequent measurements (see"Import Symbols" on page 215 ).
For signals with two different modulation types (requires option R&S FSMR3-K70M),
the color of the symbol field indicates the used Modulation and Type:
●
Green background: Pattern modulation and pattern type (for pattern only)
●
Green frame: Pattern modulation and data type (for meta data)
●
No highlighting: Data modulation and data type (for payload data)
Remote commands:
To define the required source type (see LAYout:ADD[:WINDow]? on page 431):
LAY:ADD? '1',BEL, 'XTIM:DDEM:SYMB'
To define the symbol format:
CALCulate<n>:FORMat on page 440
To query the results (see TRACe<n>[:DATA] on page 449 and Chapter 11.9.2.4,
"Symbols", on page 452):
Symbols:
TRAC1:DATA? or TRAC1:DATA? STR
Symbol errors:
TRAC1:DATA? MSTR
Pattern errors:
TRAC1:DATA? PSTR
3.2.33 Vector frequency
The instantaneous frequency of the source signal as an X/Y plot; all available samples
(as defined by the display points per symbol parameter (see "Display Points/Sym"
on page 248)) are drawn and connected.
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Available for source types:
●
"Meas & Ref Signal"
Measurements and result displays
Result types in VSA
Figure 3-28: Vector Frequency result display
A special density trace mode is available for this diagram. The occurrence of each
value within the current result range or evaluation range is indicated by color.
Remote commands:
LAY:ADD? '1',BEL,MEAS
To define the required source type (see LAYout:ADD[:WINDow]? on page 431)
CALC:FORM COVF
To define the result type (see CALCulate<n>:FORMat on page 440)
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.3, "Polar diagrams", on page 452)
3.2.34 Vector I/Q
The complex source signal as an X/Y plot; all available samples (as defined by the display points per symbol parameter, see "Display Points/Sym" on page 248) are drawn
and connected.
The scaling of the capture buffer depends on the input source:
●
Scaling is relative to the current reference level for RF input.
●
Scaling is relative to the full scale level for I/Q input.
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Result types in VSA
Available for source types:
●
"Capture Buffer"
●
"Meas & Ref Signal"
●
"Error Vector"
Capture buffer display
Note that this result display is based on an individual capture buffer range. If more than
256 000 samples are captured, overlapping ranges with a size of 256 000 each are
created. Only one range at a time can be displayed in the "Vector I/Q" result display.
For details see Chapter 4.8, "Capture buffer display", on page 146.
Figure 3-29: Vector I/Q result display
A special density trace mode is available for this diagram. The occurrence of each
value within the current result range or evaluation range is indicated by color.
Remote commands:
LAY:ADD? '1',BEL,MEAS
To define the required source type (see LAYout:ADD[:WINDow]? on page 431).
CALC:FORM COMP
To define the result type (see CALCulate<n>:FORMat on page 440).
TRAC:DATA? TRACE1
To query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chap-
ter 11.9.2.3, "Polar diagrams", on page 452).
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3.3 Predefined display configuration
Measurements and result displays
Predefined display configuration
Access: [MEAS] > "Predefined Display Config"
The R&S FSMR3000 VSA application allows you to configure the screen layout very
flexibly according to your specific measurement requirements. To get started, some
typical and useful display configurations are predefined. Select the required scenario
and the display is configured suitably.
To store your personal typical screen layout, save your current measurement settings
(including the screen layout) as a standard.
See "To store settings as a standard file" on page 252.
Typical
Provides several result displays for the most frequently required results when measuring a known signal using a specific modulation.
Overview
Provides useful result displays to determine the relevant signal characteristics of an
unknown signal.
See also the application sheet R&S®FSW-K70 Analyzing Unknown Signals on the
Rohde & Schwarz Internet site.
Remote command:
[SENSe:]DDEMod:PRESet:CALC on page 438
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3.4 Common parameters in VSA
Measurements and result displays
Common parameters in VSA
Depending on the modulation type you are using, different signal parameters are determined during vector signal analysis and displayed in the Result summary.
Details concerning the calculation of individual parameters can be found in Chap-
ter 4.5, "Signal model, estimation and modulation errors", on page 123 and Chapter F,
"Formulae", on page 513.
Table 3-4: Parameters for PSK, QAM and MSK modulation
Parameter Description SCPI parameter
"EVM - RMS/Peak" "Error Vector" Magnitude, normalized to mean reference
power by default (see "Normalize EVM to" on page 223)
"MER - RMS/Peak" Modulation Error Ratio (MER)
"Phase Error RMS"/"Peak"
"Magnitude Error RMS"/"Peak"
"Carrier Frequency
Error"
"Symbol Rate Error" Difference between the currently measured symbol rate and
"I/Q Skew" Constant time difference between the I and Q data, for
"Rho"
"I/Q Offset" Offset in the original input
The phase difference between the measurement vector and
the reference vector
The average (RMS) and peak magnitude error in %. The
magnitude error is the difference of the measured magnitude
to the magnitude of the reference signal. The magnitude
error is normalized to the mean magnitude of the reference
signal.
The mean carrier frequency offset in Hz
the defined symbol rate in ppm.
(Only if compensation for SRE is activated, see "Compen-
sate for... [ (PSK, MSK, ASK, QAM)]" on page 220)
example due to different cable lengths
(Only if compensation for I/Q skew is activated, see "Com-
pensate for... [ (PSK, MSK, ASK, QAM)]" on page 220)
EVM
SNR
PERR
MERRor
CFERror
SRER
IQSK
RHO
OOFFset
"I/Q Imbalance" Not for BPSK.
"Gain Imbalance" Not for BPSK.
"Quadrature Error" Not for BPSK.
"Amplitude Droop" The decrease of the signal power over time in the transmitter
"Power" The power of the measured signal
IQIMbalance
GIMBalance
QERRor
ADRoop
MPOWer
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Common parameters in VSA
Table 3-5: Parameters for FSK modulation only
Parameter Description SCPI parameter
"Frequency Error RMS"/"Peak"
"FSK Deviation Error" The deviation error of FSK modulated signals in Hz, i.e.
"FSK Meas Deviation" The estimated deviation of FSK modulated signals in Hz.
"FSK Ref Deviation" The reference deviation you have set in Hz.
"Carrier Frequency
Drift"
The average (RMS) and peak frequency error in %. The
frequency error is the difference of the measured frequency and the reference frequency. The frequency error
is normalized to the estimated FSK deviation.
the difference of the measured FSK deviation and the
user-defined FSK reference deviation.
The mean carrier frequency drift in Hz per symbol.
FSK:DERRor
FDERror
FSK:MDEViation
FSK:RDEViation
FSK:CFDRift
Remote command:
CALCulate<n>:MARKer<m>:FUNCtion:DDEMod:STATistic:<Parameter>?
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4 Measurement basics
Measurement basics
Filters and bandwidths during signal processing
Some background knowledge on basic terms and principles used in VSA is provided
here for a better understanding of the required configuration settings.
For information on the basic processing of I/Q data in the R&S FSMR3, see the
R&S FSMR3 I/Q Analyzer User Manual.
● Filters and bandwidths during signal processing.................................................... 69
● Sample rate, symbol rate and I/Q bandwidth..........................................................76
● Symbol mapping..................................................................................................... 78
● Overview of the demodulation process................................................................. 111
● Signal model, estimation and modulation errors...................................................123
● Measurement ranges............................................................................................ 140
● Display points vs estimation points per symbol.....................................................145
● Capture buffer display...........................................................................................146
● Known data files - dependencies and restrictions.................................................148
● Known data from PRBS generators......................................................................149
● Multi-modulation analysis (R&S FSMR3-K70M)................................................... 151
● I/Q data import and export.................................................................................... 157
4.1 Filters and bandwidths during signal processing
This section describes the used filters in vector signal analysis with an R&S FSMR3,
and the bandwidth after each filter.
The relevant filters for vector signal analysis are shown in Figure 4-1.
Figure 4-1: Block diagram of bandwidth-relevant filters for vector signal analysis
●
After the IF Filter (only for RF input operation): bandwidth = 5 MHz, 17 MHz,
80 MHz, or 500 MHz, depending on the Data acquisition settings and the installed
bandwidth options
●
After the digital hardware section:
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The phase and amplitude distortions of the IF filter have been compensated for.
Usually, the I/Q data has a usable bandwidth of about:
0.8 * sample rate
For details, refer to Chapter 4.1.1, "I/Q bandwidth", on page 70.
The I/Q data sample rate and bandwidth are automatically adjusted to the set sym-
bol rate. For most modulated signals, even the smallest allowed value for the sam-
ple rate leads to a sufficient I/Q data bandwidth. The whole spectrum of the input
signal is captured, but most adjacent channels and interferers are effectively sup-
pressed. Only for very wide signals (FSK, no TX-filter used) it can be necessary to
try higher values for the sample rate (see Chapter 4.2, "Sample rate, symbol rate
and I/Q bandwidth", on page 76), increasing the I/Q bandwidth. The I/Q data
delivered to the DSP section has no considerable amplitude or phase distortion
and a suitable bandwidth.
The "Signal Capture" dialog box ("Data Acquisition" tab) shows the sample rate and
the usable I/Q bandwidth achieved for the current settings (see "Usable I/Q Bandwidth"
on page 199).
●
After the optional measurement filter:
Various measurement filters which have different bandwidths can filter the mea-
surement signal and the reference signal.
The filters described above are the ones that directly affect the bandwidth of the captured I/Q data and the final measurement signal and reference signal. Note, however,
that several other filters are also involved in the DSP section but are not mentioned
above:
●
Receive filter to prevent ISI (intersymbol-interference)
●
Filters necessary for various estimators
●
Others
4.1.1 I/Q bandwidth
The bandwidth of the I/Q data used as input for the vector signal analysis is filtered as
described in Chapter 4.1, "Filters and bandwidths during signal processing",
on page 69. Its flat, usable bandwidth (no considerable amplitude or phase distortion)
depends on:
●
The used sample rate, which depends on:
– The defined "Symbol Rate" (see "Symbol Rate" on page 166)
– The defined "Sample Rate" parameter (see "Sample Rate" on page 199
For details on the maximum usable bandwidth, see Chapter 4.2, "Sample rate, symbol
rate and I/Q bandwidth", on page 76.
The sample rate and the usable I/Q bandwidth achieved for the current settings is displayed in the "Signal Capture" dialog, see Chapter 5.5.1, "Data acquisition",
on page 198.
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4.1.2 Demodulation bandwidth (measurement bandwidth)
4.1.3 Modulation and demodulation filters
Measurement basics
Filters and bandwidths during signal processing
Some modulation systems do not use a receive filter. In these cases, take special care
that no interference or adjacent channels occur within the demodulation bandwidth. Set
the "Sample rate" parameter to a low value (see "Sample Rate" on page 199).
Typical communication systems demand special receive or measurement filters (e.g.
root-raised cosine receive filter or EDGE measurement filter).
If no such filtering is performed, make sure that interfering signals or adjacent channels
do not fall within the demodulation bandwidth.
For demodulation, the analyzer requires sample points at which only information of the
current symbol and none of neighboring symbols is present (symbol points). These
points are also called ISI-free points (ISI = intersymbol interference). If the transmitter
does not provide an ISI-free signal after the transmit filter (TX filter), the analyzer can
filter the input signal using a receive filter or Rx filter. If the transmitter uses an RRC
(root-raised cosine) filter, the analyzer must also use an RRC filter to obtain ISI-free
points.
In many PSK systems, RRC filters are used as transmit, receive and measurement filters. To determine the I/Q modulation error, the measurement signal must be compared with the corresponding ideal signal. Therefore, the analyzer calculates a refer-
ence filter by convolving the coefficient of the transmit filter ("Tx filter") and the
"Meas filter" (see Figure 4-2).
When measuring unfiltered signals (e.g. to determine nonlinear signal distortions), no
measurement filter is switched into the signal path and the reference filter is identical
to the transmit filter (see Figure 4-2).
In the baseband block diagrams (see Figure 4-2), the system-theoretical transmitter
and analyzer filters are shown for PSK and QAM demodulation. For the sake of clearness, RF stages, IF filters and the filter stages of the digital hardware section are not
shown.
For a correct demodulation, the following filters have to be accurately specified for the
analyzer:
●
Transmit filter: filter characteristic of transmitter
●
Measurement filter:
– PSK, QAM, UserQAM, MSK:
The I and the Q part of the measurement and the reference signal are filtered
with this filter.
– FSK:
The instantaneous frequency of the measurement reference signal is filtered.
In many applications, the measurement filter is identical to the receive filter.
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Filters and bandwidths during signal processing
The receive filter (also referred to as an ISI filter) is configured internally depending on
the transmit filter. The goal is to produce intersymbol-interference-free points for the
demodulation.
The reference filter generates the ideal transmitted signal (after meas filtering). The
analyzer calculates the reference filter from the above filters (convolution operation
transmit filter * meas filter).
Typical combinations of transmit and measurement filters are shown in Table C-3; they
can be set in the R&S FSMR3000 VSA application using "Meas filter = AUTO" (see "
Using the Transmit Filter as a Measurement Filter (Auto)" on page 226). For some fil-
ters, a roll-off factor is required:
Filter type Required parameters
RC (raised cosine) Alpha
RRC (root-raised
cosine)
Gaussian BT
Alpha
Typically the Alpha/BT value of the measurement filter is the same as the value of the
transmission filter.
4.1.4 Measurement filters
The measurement filter can be used to filter the following two signals in the same way:
●
The measurement signal (after coarse frequency, phase and timing synchroniza-
tion have been achieved)
●
The reference signal, i.e the I/Q symbols that have been determined in the demod-
ulator and have already been filtered with the Transmit filter;
For FSK, the measurement filter filters the instantaneous frequency of the signal, not
the I/Q signal.
For MSK, PSK, QAM and User QAM the measurement filter filters the real part and
imaginary part of these signals (i.e. not the instantaneous frequency or magnitude of
the signal).
The R&S FSMR3000 VSA application defines the error signal as the difference
between the reference signal and the measurement signal. Thus, the measurement filter also shapes the spectrum of the error signal, which is used to calculate the EVM,
for example.
In many applications, the measurement filter is the same as the RX filter. However,
unlike the measurement filter, the RX filter is not relevant for the measurement, but is
only required to create the reference signal optimally.
If possible, the RX filter and the transmit filter are chosen such that their combination
results in an Inter-Symbol Interference (ISI) free system (see Figure 4-2 and Fig-
ure 4-3).
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Filters and bandwidths during signal processing
Figure 4-2: Measurement filter in the block diagram (MSK, PSK, QAM and UserQAM)
Figure 4-3: Modulator with Transmit filter in detail
As the measurement filters of the R&S FSMR3000 VSA application have low-pass
characteristics, they suppress high frequency distortion components in the Meas/Ref/
Error signal. The errors are weighted spectrally. Thus, turning off the measurement filter can have an influence on the numeric and graphical error values. However, to measure non-linear distortions, which usually produce high frequency components, switch
off the measurement filter.
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4.1.5 Customized filters
Measurement basics
Filters and bandwidths during signal processing
Predefined measurement filters
The most frequently required measurement filters are provided by the R&S FSMR3000
VSA application (see Chapter C.2, "Measurement filters", on page 507).
The frequency response of the available standard-specific measurement filters is
shown in Chapter F.6.2, "Measurement filter", on page 520.
The analytical filter types RC (raised cosine), RRC (root-raised cosine), GAUSSIAN,
and the most important standard-specific filters, are already integrated in the R&S
FSMR3000 VSA application. In addition, it is possible to use user-defined measurement and transmit filters. Customized filters are useful for the following purposes:
●
Developing new networks and modulation methods for which no filters are defined
yet
●
Measuring transmitter characteristics with slightly modified (e.g. shortened) trans-
mitter filters
An external program ("FILTWIZ") is offered to convert user-defined filters. This program
generates filter files (*.vaf) which can be transferred to the analyzer with a USB
device, for example. The program can be downloaded together with a detailed description as a precompiled MATLAB® file (MATLAB pcode) on the Internet, at http://
www.rohde-schwarz.com (search term "FILTWIZ").
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Figure 4-4: FILTWIZ - filter tool for VSA
It is possible to load customized transmit filters and customized measurement filters. If
you select a customized transmit filter, the internal receive filter coefficients are calculated automatically right away.
Unlike the R&S FSMR3000 VSA application, the R&S FSQ-K70 required you to transfer a user-defined receive filter, as well.
If you upload a customized transmit filter and leave the measurement filter set to "automatic", the internally calculated receive filter is used as a measurement filter. Note that
this filter is not necessarily suitable for your specific signal. The filter is optimized such
that the intersymbol interference is low. Hence, you probably see a clear eye diagram
and a "Vector I/Q" diagram with a recognizable constellation. However, a filter that has
low intersymbol interference can lead to noise enhancement, which is commonly undesirable for a measurement filter.
To avoid noise enhancement, it is recommended that you do one of the following:
●
Design your own measurement filter and upload it as a user filter.
●
Select a suitable measurement filter from the list.
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4.2 Sample rate, symbol rate and I/Q bandwidth
Measurement basics
Sample rate, symbol rate and I/Q bandwidth
Transferring filter files to the R&S FSMR3
You can transfer the (.vaf) filter files to the R&S FSMR3 using a USB memory device.
The "Symbol Rate" defined in the "Signal Description" settings determines how many
symbols are captured and demodulated during a certain measurement time. However,
for each symbol more than one sample can be captured, so that the sample rate can
be higher than the symbol rate.
The "Sample Rate" parameter in the "Signal Capture" settings defines the number of
samples to capture per symbol. (Do not confuse this number with the estimation
points per symbol or display points per symbol, see Chapter 4.7, "Display points vs
estimation points per symbol", on page 145). The resulting sample rate (depending on
the "Symbol Rate") is indicated behind the parameter.
The number of samples to capture per symbol is commonly referred to as the "Cap-
ture Oversampling" value in Rohde & Schwarz signal and spectrum analyzers.
The resulting sample rate, also referred to as the user or output sample rate, is the rate
at which the I/Q data is demodulated and analyzed. The sample rate also affects the
demodulation (measurement) bandwidth. If the bandwidth is too narrow, the signal is
not displayed completely. If the bandwidth is too wide, interference from outside the
actual signal to be measured can distort the result. Thus, for signals with a large frequency spectrum (e.g. FSK modulated signals), a higher sample rate can be necessary.
(For further details, see Chapter 4.1, "Filters and bandwidths during signal processing",
on page 69.)
For an indication of the required sample rate, view the "Real/Imag (I/Q)" display of the
capture buffer with a "Spectrum" transformation. If the complete signal is displayed
within the usable I/Q bandwidth, the selected value is suitable.
Figure 4-5: Determining the I/Q bandwidth: Real/Imag (I/Q) display of the capture buffer with a spec-
trum transformation
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Sample rate, symbol rate and I/Q bandwidth
If the signal is cut off, increase the sample rate.
If the signal is too small, decrease the sample rate by changing one of the following
settings:
●
The "Symbol Rate" defined in the "Signal Description" settings
●
The "Sample Rate" in the "Data Acquisition" settings
As described above, the sample rate defines the number of samples to capture per
symbol. Thus, the maximum sample rate depends on the maximum number of symbols
to be captured (the symbol rate) and vice versa.
The maximum sample rate for the R&S FSMR3000 is 10 GHz (see below). Thus, the
maximum symbol rate is:
Table 4-1: Maximum symbol rate depending on sample rate parameter
Sample rate parameter Max. symbol rate
2* symbol rate 5000 Msymbols
4* symbol rate 2500 Msymbols
8* symbol rate 1250 Msymbols
16* symbol rate 625 Msymbols
32* symbol rate 312.5 Msymbols
64* symbol rate 156.25 Msymbols
128* symbol rate 78.125 Msymbols
4.2.1 Sample rate and maximum usable I/Q bandwidth for RF input
Definitions
●
Input sample rate (ISR): the sample rate of the useful data provided by the device
connected to the input of the R&S FSMR3000
●
(User, Output) Sample rate (SR): the user-defined sample rate (e.g. in the "Data
Acquisition" dialog box in the "I/Q Analyzer" application) which is used as the basis
for analysis or output
●
Usable I/Q (analysis) bandwidth: the bandwidth range in which the signal
remains undistorted in regard to amplitude characteristic and group delay; this
range can be used for accurate analysis by the R&S FSMR3
●
Record length: the number of I/Q samples to capture during the specified mea-
surement time; calculated as the measurement time multiplied by the sample rate
For the I/Q data acquisition, digital decimation filters are used internally in the
R&S FSMR3000. The passband of these digital filters determines the maximum usable
I/Q bandwidth. In consequence, signals within the usable I/Q bandwidth (passband)
remain unchanged, while signals outside the usable I/Q bandwidth (passband) are
suppressed. Usually, the suppressed signals are noise, artifacts, and the second IF
sideband. If frequencies of interest to you are also suppressed, try to increase the output sample rate, which increases the maximum usable I/Q bandwidth.
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4.2.1.1 Relationship between sample rate, record length and usable I/Q bandwidth
Measurement basics
Symbol mapping
As a rule, the usable I/Q bandwidth is proportional to the output sample rate. Yet, when
the I/Q bandwidth reaches the bandwidth of the analog IF filter (at very high output
sample rates), the curve breaks.
● Relationship between sample rate, record length and usable I/Q bandwidth......... 78
Up to the maximum bandwidth, the following rule applies:
Usable I/Q bandwidth = 0.8 * Output sample rate
Regarding the record length, the following rule applies:
Record length = Measurement time * sample rate
Maximum record length for RF input
The maximum record length, that is, the maximum number of samples that can be captured, depends on the sample rate.
Table 4-2: Maximum record length
Sample rate Maximum record length
100 Hz to 200 MHz 440 Msamples
200 MHz to 20 GHz
(upsampling)
Usable I/Q
bandwidth [MHz]
90
80
70
60
50
40
30
20
10
20 40 60 80 100 120 140
220 Msamples
RF input:
BW = 0.80*f
80 MHz bandwidth
out
[…] 10000
Output sample
rate f
[MHz]
out
Figure 4-6: Relationship between maximum usable I/Q bandwidth and output sample rate
4.3 Symbol mapping
Mapping or symbol mapping means that symbol numbers are assigned to constellation
points or transitions in the I/Q plane (e.g. PSK and QAM).
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Symbol mapping
In the analyzer, the mapping is required to decode the transmitted symbols from the
sampled I/Q or frequency/time data records.
The mappings for all standards used in the analyzer and for all employed modulation
modes are described in the following. Unless indicated otherwise, symbol numbers are
specified in hexadecimal form (MSB at the left).
● Phase shift keying (PSK)........................................................................................ 79
● Rotating PSK...........................................................................................................83
● Differential PSK.......................................................................................................86
● Rotating differential PSK modulation...................................................................... 87
● Offset QPSK............................................................................................................89
● Shaped offset QPSK...............................................................................................90
● Frequency shift keying (FSK)..................................................................................91
● Minimum shift keying (MSK)................................................................................... 95
● Quadrature amplitude modulation (QAM)............................................................... 96
● ASK.......................................................................................................................108
● APSK.....................................................................................................................109
● User-defined modulation....................................................................................... 110
4.3.1 Phase shift keying (PSK)
With this type of modulation, the information is represented by the absolute phase
position of the received signal at the decision points. All transitions in the I/Q diagram
are possible. The complex constellation diagram is shown. The symbol numbers are
entered in the diagram according to the mapping rule.
BPSK (NATURAL, SMx)
Figure 4-7: Constellation diagram for BPSK including the symbol mapping
0 1
BPSK (NATURAL) is the BPSK mapping used by supported R&S SMx signal generators when using PRBS algorithms. See "Symbol mapping in accordance with the PRBS
generator" on page 151.
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Symbol mapping
QPSK
2
3
Figure 4-8: Constellation diagram for QPSK including the symbol mapping for CDMA2000 FWD, DVB-
S2 and DVB-RCS2
1
3
0
1
0
2
Figure 4-9: Constellation diagram for QPSK (GRAY) including the symbol mapping
0 1
2 3
Figure 4-10: Constellation diagram for QPSK (NATURAL, SMx) including the symbol mapping
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Symbol mapping
QPSK (NATURAL) is the QPSK mapping used by supported R&S SMx signal generators when using PRBS algorithms. See "Symbol mapping in accordance with the PRBS
generator" on page 151.
1
3
2
Figure 4-11: Constellation diagram for QPSK including the symbol mapping for WCDMA
0
8PSK
3
1 2
6
7
0
4
5
Figure 4-12: Constellation diagram for 8PSK (GRAY) including the symbol mapping
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2
3
4
5
6
Figure 4-13: Constellation diagram for 8PSK (NATURAL, SMx) including the symbol mapping
1
0
7
Figure 4-14: Constellation diagram for 8PSK including the symbol mapping for DVB-RCS2
8PSK (NATURAL) is the 8PSK mapping used by supported R&S SMx signal generators when using PRBS algorithms. See "Symbol mapping in accordance with the PRBS
generator" on page 151.
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4
6
3
Figure 4-15: Constellation diagram for 8PSK including the symbol mapping for DVB-S2
4.3.2 Rotating PSK
A rotating PSK modulation is basically a PSK modulation in which additional phase
shifts occur. These phase shifts depend on the symbol number, e.g. for a π/4-QPSK,
the third symbol has an additional phase offset of (3-1)*π/4. This offset has the same
effect as a rotation of the basic system of coordinates by the offset angle after each
symbol.
The method is highly important in practical applications because it prevents signal transitions through the zeros in the I/Q plane. This reduces the dynamic range of the
modulated signal and the linearity requirements for the amplifier.
0
1 2
5
7
In practice, the method is used for 3π/8-8PSK, for example, and (in conjunction with
phase-differential coding) for π/4-DQPSK.
Symbol mapping
The logical constellation diagram for 3π/8-8PSK comprises 8 points that correspond to
the modulation level (see Figure 4-16). A counter-clockwise offset (rotation) of 3π/8 is
inserted after each symbol transition.
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2
0
1
5 6
4
Figure 4-16: Constellation diagram for 3π/8 8PSK before rotation including the symbol mapping for
EDGE
3
7
Figure 4-17: I/Q symbol stream after 3π/8 rotation in I/Q plane if the symbol number "7" is transmitted
Figure 4-18: Constellation diagram for 3π/4 QPSK including the symbol mapping for EDGE
six times in a row
2
3
0
1
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1
2
0
3
Figure 4-19: Constellation diagram for π/4 QPSK (Natural) including the symbol mapping
1
3
2
Figure 4-20: Constellation diagram forπ/4 QPSK (GRAY) including the symbol mapping
0
0 1
Figure 4-21: Constellation diagram for π/2 BPSK (Natural, DVB-RCS2) and -π/2 BPSK including the
symbol mapping
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4.3.3 Differential PSK
Measurement basics
Symbol mapping
With differential PSK, the information is represented in the phase shift between two
consecutive decision points. The absolute position of the complex sample value at the
decision point does not carry information.
In the physical constellation diagram, the constellation points at the symbol decision
points obtained after ISI-free demodulation are shown (as with common PSK methods). This diagram corresponds to the display on the analyzer. The position of the constellation points is standard-specific. For example, some QPSK standards define the
constellation points on the diagonals, while other standards define the coordinate axes.
In Table 4-3, the symbols are assigned to phase shifts. The QPSK (INMARSAT) map-
ping corresponds to simple QPSK with phase-differential coding.
Tables Table 4-4 and Table 4-5 show two types of differential 8PSK modulation.
Differential coding according to VDL is shown in Table 4-6. It can be used for modula-
tion types with 3 bits/symbol, e.g. 8PSK.
Other types of modulation using differential coding method are described in Chap-
ter 4.3.4, "Rotating differential PSK modulation", on page 87.
Figure 4-22: Constellation diagram for DQPSK (INMARSAT and NATURAL) including the symbol map-
Table 4-3: DQPSK (INMARSAT)
Logical symbol mapping
Modulation symbol (binary indication: MSB, LSB) 00 01 10 11
Phase shift 0° -90° +90° 180°
ping
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Figure 4-23: Constellation diagram for D8PSK including the symbol mapping for APCO25, APCO25
Table 4-4: D8PSK (NATURAL)
Logical symbol mapping
Modulation symbol (binary indication: MSB, LSB)
Phase shift 0° 45° 90° 135° 180° 225° 270° 315°
Table 4-5: D8PSK (GRAY)
Logical symbol mapping
Modulation symbol (binary indication: MSB, LSB)
Phase shift 0° 45° 135° 90° 270° 315° 225° 180°
Table 4-6: D8PSK (VDL)
Logical symbol mapping
Modulation symbol (binary indication: MSB, LSB)
Phase shift 0° 45° 135° 90° 315° 270° 180° 225°
Phase 2, GRAY, NATURAL and TETRA
000 001 010 011 100 101 110 111
000 001 010 011 100 101 110 111
000 001 010 011 100 101 110 111
4.3.4 Rotating differential PSK modulation
Phase-differential modulation is frequently combined with an additional phase shift
(e.g. π/4 DQPSK = π/4 phase shift modulation + differential modulated 4PSK).
The logical mapping diagram corresponds to the diagram for DPSK.
The physical constellation diagram shows the symbol decision points obtained after
ISI-free demodulation.
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Figure 4-24: Constellation diagram for π/4 DQPSK including the symbol mapping for APCO25 Phase
Table 4-7: π/4 DQPSK (NADC, PDC, PHS, TETRA)
Logical symbol mapping
Modulation symbol (binary indication: MSB, LSB) 00 01 10 11
Phase shift 0°+45° 90°+45° -90°+45° -180°+45°
Table 4-8: π/4 DQPSK (TFTS)
Logical symbol mapping
Modulation symbol (binary indication: MSB, LSB) 00 01 10 11
Phase shift -180°+45° 90°+45° -90°+45° 0°+45°
Table 4-9: π/4 DQPSK (NATURAL, SMx)
Logical symbol mapping
Modulation symbol (binary indication: MSB, LSB) 00 01 10 11
Phase shift 0°+45° 90°+45° -180°+45° -90°+45°
Table 4-10: π/4 DQPSK (APCO25 and APCO25Phase2)
2, NADC, NATURAL, PDC, PHS, TETRA and TFTS; the π/4 rotation is already compensated for
Logical symbol mapping
Modulation symbol (binary indication: MSB, LSB) 00 01 10 11
Phase shift 0°+45° 90°+45° -90°+45° -180°+45°
Table 4-11: π/2 DBPSK
Logical symbol mapping
Modulation symbol (binary indication: MSB, LSB) 0 1
Phase shift 0°+90° -180°+90°
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4.3.5 Offset QPSK
Measurement basics
Symbol mapping
Offset QPSK differs from "normal" QPSK in the fact that the Q component is delayed
by half a symbol period against the I component in the time domain. Hence, the symbol
time instants of the I and the Q component do not coincide. The concept of Offset
QPSK is illustrated in the diagrams below.
Derivation of OQPSK
Table 4-12: I/Q diagram and constellation diagram
QPSK OQPSK (delayed Q component)
2
1
0
Inphase
-1
-2
0 1 2 3 4 5 6 7 8 9
2
1
re
0
Quadratu
-1
-2
0 1 2 3 4 5 6 7 8 9
Time
[symbols]
1
0
1
0
2
1
e
0
Inphas
-1
-2
0 1 2 3 4 5 6 7 8 9
2
1
e
0
Quadratur
-1
-2
0 1 2 3 4 5 6 7 8 9
Time
[symbols]
PSK vector diagram with alpha = 0.35 OQPSK vector diagram with alpha = 0.35
2
1
0
Quadrature
-1
2
1
0
Quadrature
-1
1
0
1
0
-2
-2 -1 0 1 2
Inphase
-2
-2 -1 0 1 2
Inphase
Offset QPSK reduces the dynamic range of the modulated signal (compared to "normal" QPSK) and, therefore, the demands on amplifier linearity by avoiding zero crossings.
A distinction is made in the analyzer display:
In the "Vector I/Q" result display of the measurement (or reference) signal, the time
delay is not compensated for. The display corresponds to the physical diagram shown
in (Table 4-12)
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Symbol mapping
In the "Constellation I/Q" result display of the measurement (or reference) signal, the
time delay is compensated for. The display corresponds to the logical mapping as in
Figure 4-25.
OQPSK
2
3
Figure 4-25: Constellation diagram for OQPSK (GRAY) including the symbol mapping
0
1
0 1
2 3
Figure 4-26: Constellation diagram for OQPSK (NATURAL, SMx) including the symbol mapping
OQPSK (NATURAL) is the OQPSK mapping used by supported R&S SMx signal generators when using PRBS algorithms. See "Symbol mapping in accordance with the
PRBS generator" on page 151.
4.3.6 Shaped offset QPSK
Shaped Offset QPSK is a constant envelope modulation whose phase at any instant in
time is either stationary or is moving at a rate of one-quarter of the bit rate. It can therefore also be interpreted as a ternary CPM.
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Symbol mapping
2
3
Figure 4-27: Constellation diagram for Shaped Offset QPSK including the symbol mapping
0
1
4.3.7 Frequency shift keying (FSK)
To illustrate symbol mappings for FSK modulations, the symbol numbers are marked in
the logical mapping diagram versus the instantaneous frequency. An instantaneous
frequency of zero in the baseband corresponds to the input frequency of the analyzer.
2FSK (NATURAL)
With 2FSK, the symbol decision is made by a simple frequency discriminator:
Symbol
Numbers
1
1
-1
0
Figure 4-28: Constellation diagram for 2FSK (NATURAL, SMx) including the logical symbol mapping
2FSK (NATURAL) is the 2FSK mapping used by supported R&S SMx signal generators when using PRBS algorithms. See "Symbol mapping in accordance with the PRBS
generator" on page 151.
4FSK
With 4FSK, the symbol decision is made by a frequency discriminator with 3 decision
thresholds (-2/3; 0; +2/3) normalized to the FSK reference deviation.
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13
Symbol
Numbers
1/3
2
-1/3
1
-10
Figure 4-29: Constellation diagram for 4FSK (NATURAL, SMx) including the logical symbol mapping
4FSK (NATURAL) is the 4FSK mapping used by supported R&S SMx signal generators when using PRBS algorithms. See "Symbol mapping in accordance with the PRBS
generator" on page 151.
12
Symbol
Numbers
1/3
3
-1/3
1
-10
Figure 4-30: Constellation diagram for 4FSK (GRAY) including the logical symbol mapping
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Symbol
Numbers
Measurement basics
Symbol mapping
11
1/3
0
-1/3
2
-13
Figure 4-31: Constellation diagram for 4FSK for APCO C4FM and APCO Phase 2 including the logical
symbol mapping
8FSK (NATURAL)
17
5/7
6
3/7
Symbol
Numbers
Figure 4-32: Constellation diagram for 8FSK (NATURAL) including the logical symbol mapping
5
1/74
-1/73
-3/7
2
-5/7
1
-10
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16 FSK
Figure 4-33: Constellation diagram for 16FSK including the logical symbol mapping
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32FSK
Figure 4-34: Constellation diagram for 32FSK including the logical symbol mapping
4.3.8 Minimum shift keying (MSK)
MSK modulation causes modulation-dependent phase shifts of +/- 90° which can be
shown in a "Constellation I/Q" diagram. As with PSK, the phase positions are evaluated during demodulation.
Table 4-13: MSK (NATURAL)
Logical symbol mapping
Modulation symbol (binary indication: MSB, LSB) 0 1
Phase shift -90° +90°
Table 4-14: MSK (GSM)
Logical symbol mapping
Modulation symbol (binary indication: MSB, LSB) 0 1
Phase shift +90° -90°
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Figure 4-35: MSK (for GSM and NATURAL) and DMSK Constellation Diagram including the symbol
mapping
Similar to PSK, differential coding can also be used with MSK. In this case, too, the
information is represented by the transition of two consecutive symbols. The block diagram of the coder is shown below.
Figure 4-36: DMSK: differential encoder in the transmitter
d
input symbol {0;1} of differential encoder
i
d
input symbol delayed by the symbol period Ts
i-1
'
d
output symbol {0;1} of differential encoder
i
The logical symbol mapping is then performed on the XOR-coded bitstream d'.
4.3.9 Quadrature amplitude modulation (QAM)
With QAM, the information is represented by the signal amplitude and phase.
The symbols are arranged in a square constellation in the I/Q plane.
To ensure reliable demodulation, symbol numbers should be distributed evenly across
the symbol alphabet.
As a rule of thumb, the result length should correspond to at least 8 times the modulation order. For example, with 64 QAM, a result length of at least 8*64 = 512 symbols
should be used.
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Symbol mapping
QAM Mappings
The following QAM mappings are obtained from the mapping of the first quadrant. The
subsequent quadrants are always rotated by π/2 and supplemented by a (GRAYcoded) prefix for each quadrant.
Table 4-15: Derivation of QAM mappings
In the following diagrams, the symbol mappings are indicated in hexadecimal and
binary form.
0 1 2 3
4 5 6 7
C D E F
8 9 A B
Figure 4-37: Constellation diagram for 16QAM (GRAY) including the logical symbol mapping (hexa-
decimal and binary)
0000 0001 0010 0011
0100 0101 0110 0111
1100 1101 1110 1111
1000 1001 1010 1011
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B
A
E
F
Figure 4-38: Constellation diagram for 16QAM including the logical symbol mapping for EDGE (hexa-
B
A
9
8
C
D
decimal and binary)
9
8
1
0
4
5
2 3
0 1
3
2
6
7
1011
1010
1110
1111
1011
1010
1001
1000
1100
1101
1001
1000
0001
0000
0100
0101
0010 0011
0000 0001
0011
0010
0110
0111
C D
E F
Figure 4-39: Constellation diagram for 16QAM including the logical symbol mapping for DVB-C (hex-
adecimal and binary)
4
5
6
7
1100 1101
1110 1111
0100
0101
0110
0111
16QAM DVB-C is the 16QAM mapping used by supported R&S SMx signal generators
when using PRBS algorithms. See "Symbol mapping in accordance with the PRBS
generator" on page 151.
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Symbol mapping
Figure 4-40: Constellation diagram for 16QAM including the logical symbol mapping for DVB-RCS2
(hexadecimal and binary)
02
06
13
16
1B
1F
17
15
14
1A
04 05
11 12
00 01
10
08
18 19
09 0A
1C 1D
0B
1E
0C
0D
0F
07
03
0E
10110
11011
11111
10111
10101
10100
11010
10011
10001 10010
10000
11000 11001
11100 11101
11110
00010
00110
00100 00101
00000 00001
01000
01001 01010
01011
01100
01101
01111
00111
00011
01110
Figure 4-41: Constellation diagram for 32QAM including the logical symbol mapping for DVB-C (hex-
adecimal and binary)
32QAM DVB-C is the 32QAM mapping used by supported R&S SMx signal generators
when using PRBS algorithms. See "Symbol mapping in accordance with the PRBS
generator" on page 151.
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2C
2E
2D
2F
29
2B
28
2A
34 35
36 37
3E 3F
3C 3D
26
27
23
22
24
25
21
20
30 31
32 33
3A 3B
38 39
08 09
0A 0B
02 03
00 01
10
12
11
13
15
17
14
16
1A
1B
1F
1E
0C 0D
0E 0F
06 07
04 05
18
19
1D
1C
001000 001001
001010 001011
000010 000011
000000 000001
001100 001101
001110 001111
000110 000111
000100 000101
Figure 4-42: Constellation diagram for 64QAM including the logical symbol mapping for DVB-C (hex-
adecimal and binary); the binary form shows the upper right section of the diagram
only.
64QAM DVB-C is the 64QAM mapping used by supported R&S SMx signal generators
when using PRBS algorithms. See "Symbol mapping in accordance with the PRBS
generator" on page 151.
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