Rohde & Schwarz VSE-K70 User Manual
R&S®VSE-K70
Vector Signal Analysis Application
User Manual
(;ÚçÁ2)
1176895102
User Manual
Version 07
This manual applies to the following software, version 1.50 and later:
●
R&S®VSE Enterprise Edition base software (1320.7500.xx / 1320.7951.xx)
●
R&S®VSE Basic Edition base software (1345.1011.06)
The following software options are described:
●
R&S VSE-K70 (1320.7522.xx)
●
R&S®CMA-K305 (1320.7939.xx)
© 2018 Rohde & Schwarz GmbH & Co. KG
Mühldorfstr. 15, 81671 München, Germany
Phone: +49 89 41 29 - 0
Fax: +49 89 41 29 12 164
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.
1176.8951.02 | Version 07 | R&S®VSE-K70
The following abbreviations are used throughout this manual: R&S®VSE is abbreviated as R&S VSE.
R&S®VSE-K70
1.1 About this Manual......................................................................................................... 7
1.2 Typographical Conventions......................................................................................... 8
2.1 Introduction to Vector Signal Analysis....................................................................... 9
2.2 Starting the VSA Application..................................................................................... 10
2.3 Understanding the Display Information.................................................................... 11
3.1 Evaluation Data Sources in VSA............................................................................... 14
3.2 Result Types in VSA....................................................................................................19
Contents
Contents
1 Preface.................................................................................................... 7
2 Welcome to the Vector Signal Analysis Application.......................... 9
3 Measurements and Result Displays...................................................14
3.3 Predefined Display Configuration............................................................................. 58
3.4 Common Parameters in VSA..................................................................................... 59
4 Measurement Basics........................................................................... 61
4.1 Filters and Bandwidths during Signal Processing.................................................. 61
4.2 Sample Rate, Symbol Rate and I/Q Bandwidth........................................................ 68
4.3 Symbol Mapping......................................................................................................... 70
4.4 Overview of the Demodulation Process................................................................. 100
4.5 Signal Model, Estimation and Modulation Errors.................................................. 114
4.6 Measurement Ranges............................................................................................... 131
4.7 Display Points Vs Estimation Points Per Symbol..................................................136
4.8 Capture Buffer Display............................................................................................. 138
4.9 Known Data Files - Dependencies and Restrictions............................................. 139
5 Configuration......................................................................................141
5.1 Configuration Overview............................................................................................141
5.2 Configuration According to Digital Standards.......................................................145
5.3 Signal Description.....................................................................................................147
5.4 Input, Output and Frontend Settings.......................................................................155
5.5 Signal Capture...........................................................................................................175
5.6 Burst and Pattern Configuration............................................................................. 182
5.7 Result Range Configuration.....................................................................................192
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5.8 Demodulation Settings............................................................................................. 194
5.9 Measurement Filter Settings.................................................................................... 202
5.10 Evaluation Range Configuration............................................................................. 204
5.11 Adjusting Settings Automatically............................................................................206
6.1 Trace Settings............................................................................................................209
6.2 Trace Export Settings............................................................................................... 212
6.3 Markers...................................................................................................................... 213
6.4 Limit and Display Lines............................................................................................ 219
6.5 Display and Window Configuration.........................................................................223
7.1 How to Perform VSA According to Digital Standards........................................... 227
Contents
6 Analysis.............................................................................................. 209
7 How to Perform Vector Signal Analysis...........................................227
7.2 How to Perform Customized VSA Measurements................................................. 229
7.3 How to Analyze the Measured Data.........................................................................239
8 Measurement Examples.................................................................... 247
8.1 Connecting the Transmitter and Analyzer..............................................................247
8.2 Measurement Example 1: Continuous QPSK Signal............................................. 247
8.3 Measurement Example 2: Burst GSM EDGE Signals............................................ 254
9 Troubleshooting the Measurement.................................................. 264
9.1 Flow Chart for Troubleshooting...............................................................................264
9.2 Explanation of Error Messages............................................................................... 266
9.3 Frequently Asked Questions................................................................................... 275
10 Remote Commands for VSA............................................................. 283
10.1 Introduction............................................................................................................... 283
10.2 Common Suffixes......................................................................................................288
10.3 Activating VSA Measurements................................................................................ 288
10.4 Configuring VSA....................................................................................................... 289
10.5 Analysis..................................................................................................................... 362
10.6 Configuring the Result Display................................................................................387
10.7 Retrieving Results.....................................................................................................405
10.8 Status Reporting System......................................................................................... 430
10.9 Programming Examples........................................................................................... 441
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A Menu Reference................................................................................. 451
A.1 Common R&S VSE Menus....................................................................................... 451
A.2 Vector Signal Analysis Menus................................................................................. 453
B Reference of Toolbar Functions....................................................... 457
C Abbreviations..................................................................................... 461
D Predefined Standards and Settings................................................. 462
E Predefined Measurement and Tx Filters.......................................... 470
E.1 Transmit Filters......................................................................................................... 470
E.2 Measurement Filters................................................................................................. 471
E.3 Typical Combinations of Tx and Measurement Filters.......................................... 472
Contents
Annex.................................................................................................. 449
F ASCII File Export Format for VSA Data............................................473
G Known Data File Syntax Description................................................475
H Formulae.............................................................................................477
H.1 Trace-based Evaluations..........................................................................................477
H.2 Result Summary Evaluations...................................................................................479
H.3 Statistical Evaluations for the Result Summary.................................................... 482
H.4 Trace Averaging........................................................................................................ 483
H.5 Analytically Calculated Filters................................................................................. 483
H.6 Standard-Specific Filters..........................................................................................484
List of Remote Commands (VSA).....................................................491
Index....................................................................................................501
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Contents
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1 Preface
1.1 About this Manual
Preface
About this Manual
This R&S VSE VSA User Manual provides all the information specific to the applica-
tion. All general software functions and settings common to all applications and operating modes are described in the R&S VSE Base Software User Manual.
The main focus in this manual is on the measurement results and the tasks required to
obtain them. The following topics are included:
●
Welcome to the R&S VSE VSA application Application
Introduction to and getting familiar with the application
●
Measurements and Result Displays
Details on supported measurements and their result types
●
Measurement Basics
Background information on basic terms and principles in the context of the measurement
●
Configuration + Analysis
A concise description of all functions and settings available to configure measurements and analyze results with their corresponding remote control command
●
How to Perform Measurements in the R&S VSE VSA application Application
The basic procedure to perform each measurement and step-by-step instructions
for more complex tasks or alternative methods
●
Measurement Examples
Detailed measurement examples to guide you through typical measurement scenarios and allow you to try out the application immediately
●
Optimizing and Troubleshooting the Measurement
Hints and tips on how to handle errors and optimize the measurement configuration
●
Remote Commands for R&S VSE VSA application Measurements
Remote commands required to configure and perform R&S VSE VSA application
measurements in a remote environment, sorted by tasks
(Commands required to set up the environment or to perform common tasks in the
software are provided in the R&S VSE Base Software User Manual)
Programming examples demonstrate the use of many commands and can usually
be executed directly for test purposes
●
Annex
Reference material
●
List of remote commands
Alphabetical list of all remote commands described in the manual
●
Index
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1.2 Typographical Conventions
Preface
Typographical Conventions
The following text markers are used throughout this documentation:
Convention Description
"Graphical user interface elements"
[Keys] Key and knob names are enclosed by square brackets.
File names, commands,
program code
Input Input to be entered by the user is displayed in italics.
Links Links that you can click are displayed in blue font.
"References" References to other parts of the documentation are enclosed by quota-
All names of graphical user interface elements on the screen, such as
dialog boxes, menus, options, buttons, and softkeys are enclosed by
quotation marks.
File names, commands, coding samples and screen output are distinguished by their font.
tion marks.
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2 Welcome to the Vector Signal Analysis
Welcome to the Vector Signal Analysis Application
Introduction to Vector Signal Analysis
Application
The R&S VSE 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.
TheR&S VSE 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 analysis of the measured signal and the reference signal
●
Flexible burst search for the analysis of complex signal combinations, short bursts
or signal mix
This user manual contains a description of the functionality that the application provides, including remote control operation.
Functions that are not discussed in this manual are the same as in the I/Q Analyzer
application and are described in the R&S VSE Base Software User Manual. The latest
version is available for download at the product homepage http://www.rohde-
schwarz.com/product/VSE.html.
Additional information
Several application notes discussing vector signal analysis using the R&S VSE 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
● Introduction to Vector Signal Analysis.......................................................................9
● Starting the VSA Application...................................................................................10
● Understanding the Display Information................................................................... 11
2.1 Introduction to Vector Signal Analysis
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.
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Welcome to the Vector Signal Analysis Application
Starting the VSA Application
After extracting the reference signal, the R&S VSE 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
2.2 Starting the VSA Application
Vector Signal Analysis is a separate application on the R&S VSE. It is activated by creating a new measurement channel in VSA mode.
To activate the VSA application
1.
Select the "Add Channel" function in the Sequence tool window.
A dialog box opens that contains all operating modes and applications currently
available in your R&S VSE.
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Welcome to the Vector Signal Analysis Application
Understanding the Display Information
2. Select the "VSA" item.
The R&S VSE opens a new measurement channel for the R&S VSE VSA application.
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 Vector Signal Analysis Application
Understanding the Display Information
1 = Color coding for windows of same channel
2 = Channel bar with measurement settings
3 = Window title bar with diagram-specific (trace) information
4 = Diagram area
5 = Diagram footer with diagram-specific information, depending on result display
Channel bar information
In the R&S VSE VSA application, the R&S VSE shows the following settings:
Table 2-1: Information displayed in the channel bar in VSA application
Ref Level Reference level
Freq Center frequency for the RF signal
Offset Reference level offset
Att Mechanical and electronic RF attenuation
STD/Mod Digital standard or modulation type, if no standard is active (or default
standard is changed)
Res Len/ Cap Len Result length or capture length (for capture buffer display), see "Capture
Length Settings" on page 176
SR Symbol Rate
Burst Burst search active (see "Enabling Burst Searches" on page 184)
Pattern Pattern search active (see "Enabling Pattern Searches" on page 186)
Stat Count Statistics count for averaging and other statistical operations, see "Statis-
tic Count" on page 178; cannot be edited directly
Capt Count Capture count; the current number of captures performed if several cap-
tures are necessary to obtain the number of results defined by "Statistics
Count"; cannot be edited directly
Result Range # Selected result range (see "Select Result Rng" on page 193)
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Welcome to the Vector Signal Analysis Application
Understanding the Display Information
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 VSE Base Software User Manual.
Window title bar information
For each diagram, the header provides the following information:
Figure 2-2: Window title bar information in VSA application
0 = Color coding for windows of same channel
1 = Edit result display function
2 = Channel name
3 = Window number
4 = Window type
5 = Data source type
6 = Trace color, trace number, displayed signal for Meas&Ref data source: M (Meas) or R (Ref), trace mode
7 = Dock/undock window function
8 = Close window function
Diagram area
The diagram area displays the results according to the selected result displays (see
Chapter 3, "Measurements and Result Displays", on page 14).
Diagram footer information
The diagram footer (beneath the diagram) contains the start and stop symbols or time
of the evaluation range.
Status bar information
The software status, errors and warnings and any irregularities in the software are indicated in the status bar at the bottom of the R&S VSE window.
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3 Measurements and Result Displays
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 131.)
Result display windows
For each measurement, a separate measurement channel is activated. Each measurement channel can provide multiple result displays, which are displayed in individual
windows. The measurement windows can be rearranged and configured in the
R&S VSE to meet your requirements. All windows that belong to the same measurement (including the channel bar) are indicated by a colored line at the top of the window title bar.
In the R&S VSE VSA application, a maximum of 24 windows are available.
►
To add further result displays for the VSA channel, select the
from the toolbar, or select the "Window > New Window" menu item.
For details on working with channels and windows see the "Operating Basics"
chapter in the R&S VSE Base Software User Manual.
● Evaluation Data Sources in VSA.............................................................................14
● Result Types in VSA............................................................................................... 19
● Predefined Display Configuration............................................................................58
● Common Parameters in VSA..................................................................................59
3.1 Evaluation Data Sources in VSA
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 223.
"Add Window" icon
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Measurements and Result Displays
Evaluation Data Sources in VSA
In diagrams in the frequency domain (Spectrum transformation, see "Result Type
Transformation" on page 224) the usable I/Q bandwidth is indicated by vertical blue
lines.
Capture Buffer...............................................................................................................15
Measurement & Reference Signal................................................................................ 16
Symbols........................................................................................................................ 16
Error Vector...................................................................................................................16
Modulation Errors..........................................................................................................17
Modulation Accuracy.....................................................................................................17
Equalizer....................................................................................................................... 18
Multi Source.................................................................................................................. 18
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.
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Measurements and Result Displays
Evaluation Data Sources in VSA
You can change the position of the result range quickly and easily by dragging the blue
bar representing the result range to a different position in the capture buffer.
If the optional 2 GHz bandwidth extension (B2000) is active, the capture buffer is
restricted to 256 000 samples; thus, all data is included in one single range.
The default result type is "Magnitude Absolute".
The following result types are available:
●
Chapter 3.2.21, "Magnitude Absolute", on page 40
●
Chapter 3.2.22, "Magnitude Overview Absolute", on page 41
●
Chapter 3.2.28, "Real/Imag (I/Q)", on page 47
●
Chapter 3.2.11, "Frequency Absolute", on page 30
●
Chapter 3.2.34, "Vector I/Q", on page 57
Remote command:
LAY:ADD? '1',BEL,TCAP(see LAYout:ADD[:WINDow]? on page 392)
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 40
●
Chapter 3.2.23, "Magnitude Relative", on page 43
●
Chapter 3.2.26, "Phase Wrap", on page 45
●
Chapter 3.2.27, "Phase Unwrap", on page 46
●
Chapter 3.2.11, "Frequency Absolute", on page 30
●
Chapter 3.2.12, "Frequency Relative", on page 32
●
Chapter 3.2.28, "Real/Imag (I/Q)", on page 47
●
Chapter 3.2.10, "Eye Diagram Real (I)", on page 30
●
Chapter 3.2.9, "Eye Diagram Imag (Q)", on page 29
●
Chapter 3.2.8, "Eye Diagram Frequency", on page 28
●
Chapter 3.2.5, "Constellation I/Q", on page 25
●
Chapter 3.2.34, "Vector I/Q", on page 57
●
Chapter 3.2.4, "Constellation Frequency", on page 24
●
Chapter 3.2.33, "Vector Frequency", on page 56
Remote command:
LAY:ADD? '1',BEL,REF(see LAYout:ADD[:WINDow]? on page 392)
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 55).
Remote command:
LAY:ADD? '1',BEL, SYMB(see LAYout:ADD[:WINDow]? on page 392)
Error Vector
The modulated difference between the complex measurement signal and the complex
reference signal:
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Measurements and Result Displays
Evaluation Data Sources in VSA
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 27
●
Chapter 3.2.28, "Real/Imag (I/Q)", on page 47
●
Chapter 3.2.34, "Vector I/Q", on page 57
Remote command:
LAY:ADD? '1',BEL,EVEC(see LAYout:ADD[:WINDow]? on page 392)
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 40
●
Chapter 3.2.25, "Phase Error", on page 44
●
Chapter 3.2.13, "Frequency Error Absolute", on page 33
●
Chapter 3.2.14, "Frequency Error Relative", on page 34
Remote command:
LAY:ADD? '1',BEL,MERR(see LAYout:ADD[:WINDow]? on page 392)
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 48
●
Chapter 3.2.1, "Bit Error Rate (BER)", on page 21
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.
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Measurements and Result Displays
Evaluation Data Sources in VSA
Remote command:
LAY:ADD? '1',BEL,MACC(see LAYout:ADD[:WINDow]? on page 392)
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 38
●
Chapter 3.2.19, "Impulse Response Phase", on page 39
●
Chapter 3.2.20, "Impulse Response Real/Imag", on page 39
●
Chapter 3.2.16, "Frequency Response Magnitude", on page 36
●
Chapter 3.2.17, "Frequency Response Phase", on page 37
●
Chapter 3.2.15, "Frequency Response Group Delay", on page 35
●
Chapter 3.2.3, "Channel Frequency Response Magnitude", on page 23
●
Chapter 3.2.2, "Channel Frequency Response Group Delay", on page 23
The default result type is "Frequency Response Magnitude".
Remote command:
LAY:ADD? '1',BEL,EQU(see LAYout:ADD[:WINDow]? on page 392)
Multi Source
Combines two data sources in one diagram, with (initially) one trace for each data
source. This 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 53
●
Chapter 3.2.31, "Spectrum (Measurement + Error)", on page 54
Remote command:
LAY:ADD? '1',RIGH,MCOM, see LAYout:ADD[:WINDow]? on page 392
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3.2 Result Types in VSA
Measurements and Result Displays
Result Types in VSA
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 400.
Table 3-1: Available result types depending on data source
Evaluation Data
Source
Capture Buffer Magnitude Absolute MAGNitude
Meas & Ref Signal Magnitude Absolute MAGNitude
Result Type SCPI Parameter
Real/Imag (I/Q) RIMag
Frequency Absolute FREQuency
Vector I/Q COMP
Magnitude Overview Absolute MOVerview
Magnitude Relative MAGNitude
Phase Wrap PHASe
Phase Unwrap UPHase
Frequency Absolute FREQuency
Frequency Relative FREQuency
Real/Imag (I/Q) RIMag
Eye Diagram Real (I) IEYE
Eye Diagram Imag (Q) QEYE
Eye Diagram Frequency FEYE
Constellation I/Q CONS
Constellation I/Q (Rotated) RCON
Vector I/Q COMP
Constellation Frequency CONF
Vector Frequency COVF
Symbols Binary -
Octal -
Decimal -
Hexadecimal -
Error Vector EVM MAGNitude
Real/Imag (I/Q) RIMag
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Measurements and Result Displays
Result Types in VSA
Evaluation Data
Source
Modulation Errors Magnitude Error MAGNitude
Modulation Accuracy Bit Error Rate BERate
Equalizer Impulse Response Magnitude MAGNitude
Result Type SCPI Parameter
Vector I/Q COMP
Phase Error PHASe
Frequency Error Absolute FREQuency
Frequency Error Relative FREQuency
Result Summary RSUM
Impulse Response Phase UPHase
Impulse Response Real/Image RIMag
Frequency Response Magnitude MAGNitude
Frequency Response Phase UPHase
Frequency Response Group Delay GDELay
Channel Frequency Response Magnitude
MAGNitude
Channel Frequency Response Group
Delay
Multi Source Spectrum (Real/Imag) (Capture buffer
+ Error)
Spectrum (Real/Imag) (Measurement
+ Error)
GDELay
RIMag (query only)
RIMag (query only)
For details on selecting the data source and result types for evaluation see Chap-
ter 6.5, "Display and Window Configuration", on page 223.
Remote command:
CALCulate<n>:FORMat on page 400
● Bit Error Rate (BER)................................................................................................21
● Channel Frequency Response Group Delay.......................................................... 23
● Channel Frequency Response Magnitude..............................................................23
● Constellation Frequency......................................................................................... 24
● Constellation I/Q......................................................................................................25
● Constellation I/Q (Rotated)......................................................................................26
● Error Vector Magnitude (EVM)................................................................................27
● Eye Diagram Frequency......................................................................................... 28
● Eye Diagram Imag (Q)............................................................................................ 29
● Eye Diagram Real (I)...............................................................................................30
● Frequency Absolute................................................................................................ 30
● Frequency Relative................................................................................................. 32
● Frequency Error Absolute....................................................................................... 33
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Measurements and Result Displays
Result Types in VSA
● Frequency Error Relative........................................................................................ 34
● Frequency Response Group Delay.........................................................................35
● Frequency Response Magnitude............................................................................ 36
● Frequency Response Phase...................................................................................37
● Impulse Response Magnitude.................................................................................38
● Impulse Response Phase....................................................................................... 39
● Impulse Response Real/Imag.................................................................................39
● Magnitude Absolute................................................................................................ 40
● Magnitude Overview Absolute................................................................................ 41
● Magnitude Relative................................................................................................. 43
● Magnitude Error...................................................................................................... 44
● Phase Error.............................................................................................................44
● Phase Wrap............................................................................................................ 45
● Phase Unwrap.........................................................................................................46
● Real/Imag (I/Q)........................................................................................................47
● Result Summary......................................................................................................48
● Spectrum (Capture Buffer + Error)..........................................................................53
● Spectrum (Measurement + Error)........................................................................... 54
● Symbol Table...........................................................................................................55
● Vector Frequency....................................................................................................56
● Vector I/Q................................................................................................................57
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 may occur. This knowledge must be
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 139).
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 VSE VSA application is provided in the software free of charge.
See Chapter 7.2.3.2, "How to Create Known Data Files", on page 236.
If known data is specified in the application, the BER result display is available for the
following source types:
●
Modulation Accuracy
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Measurements and Result Displays
Result Types in VSA
Note that this measurement may 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 106 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 BER 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:
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 392)
CALC:FORM BER
to define the result type (see CALCulate<n>:FORMat on page 400)
CALC:BER?
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3.2.2 Channel Frequency Response Group Delay
Measurements and Result Displays
Result Types in VSA
to query the results (see CALCulate<n>:BERate on page 415)
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 392)
CALC:FEED 'XFR:DDEM:IRAT'
to define the channel frequency response result type (see CALCulate<n>:FEED
on page 399)
CALC:FORM GDEL
to define the group delay result type (see CALCulate<n>:FORMat on page 400)
TRAC:DATA? TRACE1
to query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chapter 10.7.2.6,
"Equalizer", on page 414)
3.2.3 Channel Frequency Response Magnitude
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.
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Measurements and Result Displays
Result Types in VSA
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, may 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 392)
CALC:FEED 'XFR:DDEM:IRAT'
to define the channel frequency response result type (see CALCulate<n>:FEED
on page 399)
CALC:FORM MAGN
to define the magnitude result type (see CALCulate<n>:FORMat on page 400)
TRAC:DATA? TRACE1
to query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chapter 10.7.2.6,
"Equalizer", on page 414)
3.2.4 Constellation Frequency
The instantaneous frequency of 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
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Measurements and Result Displays
Result Types in VSA
Figure 3-2: Result display "Constellation Frequency"
Remote commands:
LAY:ADD? '1',BEL,MEAS
to define the required source type (see LAYout:ADD[:WINDow]? on page 392)
CALC:FORM CONF
to define the result type (see CALCulate<n>:FORMat on page 400)
TRAC:DATA? TRACE1
to query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chapter 10.7.2.3,
"Polar Diagrams", on page 413)
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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Measurements and Result Displays
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, while the marker result indicates the I and Q values of the
point.
Remote commands:
LAY:ADD? '1',BEL,MEAS
to define the required source type (see LAYout:ADD[:WINDow]? on page 392)
CALC:FORM CONS
to define the result type (see CALCulate<n>:FORMat on page 400)
TRAC:DATA? TRACE1
to query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chapter 10.7.2.3,
"Polar Diagrams", on page 413)
CALCulate<n>:MARKer<m>:Y? on page 407, 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 3-4: Result display "Constellation I/Q (Rotated)" vs. common "Constellation I/Q" for 3π/
Remote commands:
LAY:ADD? '1',BEL,MEAS
to define the required source type (see LAYout:ADD[:WINDow]? on page 392)
CALC:FORM RCON
to define the result type (see CALCulate<n>:FORMat on page 400)
TRAC:DATA? TRACE1
to query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chapter 10.7.2.3,
"Polar Diagrams", on page 413)
8-8PSK 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 225).
The normalization constant C is chosen according to the EVM normalization. By
default C² is the mean power of the reference signal.
and
Note that k=0.5·n·T for Offset QPSK with inactive Offset EVM.
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Measurements and Result Displays
Result Types in VSA
Figure 3-5: Result display "Error Vector Magnitude"
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 392)
CALC:FORM MAGN
to define the result type (see CALCulate<n>:FORMat on page 400)
TRAC:DATA? TRACE1
to query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chapter 10.7.2.2,
"Cartesian Diagrams", on page 413)
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
Remote commands:
LAY:ADD? '1',BEL,MEAS
to define the required source type (see LAYout:ADD[:WINDow]? on page 392)
CALC:FORM FEYE
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3.2.9 Eye Diagram Imag (Q)
Measurements and Result Displays
Result Types in VSA
to define the result type (see CALCulate<n>:FORMat on page 400)
TRAC:DATA? TRACE1
to query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chapter 10.7.2.2,
"Cartesian Diagrams", on page 413)
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
Figure 3-6: Result display "Eye Diagram Imag (Q)"
Remote commands:
LAY:ADD? '1',BEL,MEAS
to define the required source type (see LAYout:ADD[:WINDow]? on page 392)
CALC:FORM QEYE
to define the result type (see CALCulate<n>:FORMat on page 400)
TRAC:DATA? TRACE1
to query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chapter 10.7.2.2,
"Cartesian Diagrams", on page 413)
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3.2.10 Eye Diagram Real (I)
Measurements and Result Displays
Result Types in VSA
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 3-7: Result display "Eye Diagram Real (I)"
Remote commands:
LAY:ADD? '1',BEL,MEAS
to define the required source type (see LAYout:ADD[:WINDow]? on page 392)
CALC:FORM IEYE
to define the result type (see CALCulate<n>:FORMat on page 400)
TRAC:DATA? TRACE1
to query the trace results (see TRACe<n>[:DATA]? TRACE<n> and Chapter 10.7.2.2,
"Cartesian Diagrams", on page 413)
3.2.11 Frequency Absolute
The instantaneous frequency of the signal source; the absolute value is displayed in
Hz.
Available for source types:
●
Meas & Ref Signal
●
Capture Buffer
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