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R&S®FSW-K10
GSM Measurement
User Manual
(;×êÍ2)
1173926302
Version 27
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This manual applies to the following R&S®FSW models with firmware version 5.10 and later:
●
R&S®FSW8 (1331.5003K08 / 1312.8000K08)
●
R&S®FSW13 (1331.5003K13 / 1312.8000K13)
●
R&S®FSW26 (1331.5003K26 / 1312.8000K26)
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R&S®FSW43 (1331.5003K43 / 1312.8000K43)
●
R&S®FSW50 (1331.5003K50 / 1312.8000K50)
●
R&S®FSW67 (1331.5003K67 / 1312.8000K67)
●
R&S®FSW85 (1331.5003K85 / 1312.8000K85)
This manual applies to the following R&S®FSW models with firmware version 3.20 and higher:
●
R&S®FSW8 (1312.8000K08)
●
R&S®FSW13 (1312.8000K13)
●
R&S®FSW26 (1312.8000K26)
●
R&S®FSW43 (1312.8000K43)
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R&S®FSW50 (1312.8000K50)
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R&S®FSW67 (1312.8000K67)
●
R&S®FSW85 (1312.8000K85)
The following firmware options are described:
●
R&S FSW-K10 (1313.1368.02)
© 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.
1173.9263.02 | Version 27 | R&S®FSW-K10
Throughout this manual, products from Rohde & Schwarz are indicated without the ® symbol, e.g. R&S®FSW is indicated as
R&S FSW.
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R&S®FSW-K10
1 Documentation overview.......................................................................9
1.1 Getting started manual................................................................................................. 9
1.2 User manuals and help.................................................................................................9
1.3 Service manual..............................................................................................................9
1.4 Instrument security procedures................................................................................ 10
1.5 Printed safety instructions.........................................................................................10
1.6 Data sheets and brochures........................................................................................ 10
1.7 Release notes and open-source acknowledgment (OSA).......................................10
1.8 Application notes, application cards, white papers, etc......................................... 10
2 Welcome to the GSM application........................................................11
Contents
Contents
2.1 Starting the GSM application..................................................................................... 11
2.2 Understanding the display information.................................................................... 12
3 About the measurement......................................................................16
4 Measurements and result displays.................................................... 17
4.1 GSM I/Q measurement results................................................................................... 17
4.2 Multicarrier wideband noise measurements............................................................ 34
4.2.1 Multicarrier evaluation methods.................................................................................... 34
5 Basics on GSM measurements...........................................................45
5.1 Relevant digital standards......................................................................................... 45
5.2 Short introduction to GSM (GMSK, EDGE and EDGE evolution)........................... 45
5.3 Short introduction to VAMOS.....................................................................................49
5.4 AQPSK modulation..................................................................................................... 50
5.5 I/Q data import and export......................................................................................... 51
5.6 Trigger settings........................................................................................................... 52
5.7 Defining the scope of the measurement...................................................................53
5.8 Overview of filters in the R&S FSW GSM application..............................................55
5.8.1 Power vs time filter........................................................................................................56
5.8.2 Multicarrier filter.............................................................................................................57
5.8.3 Measurement filter........................................................................................................ 58
5.9 Dependency of slot parameters.................................................................................59
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5.10 Definition of the symbol period................................................................................. 59
5.10.1 GMSK modulation (normal symbol rate)....................................................................... 59
5.10.2 8PSK, 16QAM, 32QAM, AQPSK modulation (normal symbol rate)..............................60
5.10.3 QPSK, 16QAM and 32QAM modulation (higher symbol rate)...................................... 62
5.11 Synchronization.......................................................................................................... 63
5.12 Timeslot alignment......................................................................................................65
5.13 Delta to sync values....................................................................................................67
5.14 Limit checks................................................................................................................ 68
5.14.1 Limit check for modulation spectrum.............................................................................68
5.14.2 Limit check for transient spectrum................................................................................ 69
5.14.3 Limit check for power vs time results............................................................................ 69
5.15 Impact of the "Statistic count"...................................................................................70
5.16 Multicarrier and wideband noise............................................................................... 71
Contents
5.16.1 MCWN measurement process...................................................................................... 71
5.16.2 Contiguous vs non-contiguous multicarrier allocation...................................................73
5.16.3 Manual reference power definition for MCWN measurements..................................... 74
5.16.4 Limit check for MCWN results.......................................................................................75
5.16.5 Intermodulation calculation........................................................................................... 77
5.16.6 Wideband noise measurement..................................................................................... 80
5.17 Automatic carrier detection....................................................................................... 81
5.18 GSM in MSRA operating mode.................................................................................. 82
6 Configuration........................................................................................85
6.1 Multiple measurement channels and sequencer function...................................... 85
6.2 Display configuration................................................................................................. 87
6.3 Modulation accuracy measurement configuration.................................................. 87
6.3.1 Configuration overview..................................................................................................88
6.3.2 Signal description..........................................................................................................90
6.3.3 Input, output and frontend settings................................................................................99
6.3.4 Trigger settings............................................................................................................113
6.3.5 Data acquisition...........................................................................................................116
6.3.6 Demodulation.............................................................................................................. 120
6.3.7 Measurement settings.................................................................................................126
6.3.8 Adjusting settings automatically.................................................................................. 130
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6.4 Multicarrier wideband noise (MCWN) measurements........................................... 132
6.4.1 Default settings for GSM MCWN measurements........................................................132
6.4.2 Configuration overview................................................................................................133
6.4.3 Signal description........................................................................................................135
6.4.4 Input and frontend settings..........................................................................................139
6.4.5 Trigger settings............................................................................................................148
6.4.6 Sweep settings............................................................................................................154
6.4.7 Reference measurement settings............................................................................... 156
6.4.8 Noise measurement settings.......................................................................................158
6.4.9 Adjusting settings automatically.................................................................................. 160
7 Analysis.............................................................................................. 161
7.1 Result configuration................................................................................................. 161
Contents
7.1.1 Traces......................................................................................................................... 161
7.1.2 Markers....................................................................................................................... 163
7.1.3 Y-Axis scaling..............................................................................................................167
8 I/Q data import and export................................................................ 170
9 How to perform measurements in the GSM application................ 171
9.1 How to perform a basic measurement on GSM signals........................................ 171
9.2 How to determine modulation accuracy parameters for GSM signals................ 172
9.3 How to analyze the power in GSM signals............................................................. 174
9.4 How to analyze the spectrum of GSM signals........................................................175
9.5 How to measure wideband noise in multicarrier setups.......................................177
10 Optimizing and troubleshooting the measurement........................ 179
10.1 Improving performance............................................................................................ 179
10.2 Improving EVM accuracy......................................................................................... 179
10.3 Optimizing limit checks............................................................................................ 180
10.4 Error messages......................................................................................................... 181
11 Remote commands to perform GSM measurements..................... 182
11.1 Introduction............................................................................................................... 182
11.1.1 Conventions used in descriptions............................................................................... 183
11.1.2 Long and short form.................................................................................................... 184
11.1.3 Numeric suffixes..........................................................................................................184
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11.1.4 Optional keywords.......................................................................................................184
11.1.5 Alternative keywords................................................................................................... 185
11.1.6 SCPI parameters.........................................................................................................185
11.2 Common suffixes......................................................................................................187
11.3 Activating GSM measurements............................................................................... 187
11.4 Selecting the measurement..................................................................................... 192
11.5 Configuring and performing GSM I/Q measurements...........................................193
11.5.1 Signal description........................................................................................................193
11.5.2 Input/output settings....................................................................................................208
11.5.3 Frontend configuration................................................................................................ 227
11.5.4 Triggering measurements........................................................................................... 235
11.5.5 Data acquisition...........................................................................................................243
11.5.6 Demodulation.............................................................................................................. 250
Contents
11.5.7 Measurement.............................................................................................................. 255
11.5.8 Adjusting settings automatically.................................................................................. 261
11.6 Configuring and performing MCWN measurements............................................. 263
11.6.1 Signal description........................................................................................................263
11.6.2 Input/output and frontend settings...............................................................................263
11.6.3 Triggering measurements........................................................................................... 265
11.6.4 Configuring the reference measurement.....................................................................265
11.6.5 Configuring the noise measurement........................................................................... 268
11.6.6 Adjusting settings automatically.................................................................................. 270
11.6.7 Performing sweeps..................................................................................................... 270
11.7 Analyzing GSM measurements................................................................................270
11.7.1 Configuring the result display......................................................................................270
11.7.2 Result config............................................................................................................... 278
11.7.3 Configuring an analysis interval and line (MSRA mode only)..................................... 288
11.8 Retrieving results......................................................................................................291
11.8.1 Graphical results......................................................................................................... 291
11.8.2 Measurement results for TRACe<n>[:DATA]? TRACE<n>.........................................297
11.8.3 Magnitude capture results...........................................................................................300
11.8.4 Modulation accuracy results........................................................................................301
11.8.5 Modulation spectrum results....................................................................................... 313
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11.8.6 Power vs slot results................................................................................................... 315
11.8.7 Transient spectrum results..........................................................................................323
11.8.8 Trigger to sync results.................................................................................................325
11.8.9 Limit check results.......................................................................................................326
11.8.10 MCWN results............................................................................................................. 330
11.8.11 Retrieving marker results............................................................................................ 340
11.9 Importing and exporting I/Q data and results........................................................ 342
11.10 Status reporting system...........................................................................................343
11.10.1 STATus:QUEStionable:SYNC register........................................................................344
11.10.2 STATus:QUEStionable:LIMit register.......................................................................... 345
11.10.3 STATus:QUEStionable:DIQ register............................................................................345
11.10.4 Querying the status registers...................................................................................... 348
11.11 Troubleshooting........................................................................................................351
Contents
11.12 Deprecated commands.............................................................................................352
11.13 Programming examples........................................................................................... 361
11.13.1 Programming example: determining the EVM............................................................ 361
11.13.2 Programming example: measuring an AQPSK signal................................................ 365
11.13.3 Programming example: measuring the power for access bursts................................ 368
11.13.4 Programming example: measuring statistics.............................................................. 370
11.13.5 Programming example: measuring the wideband noise for multiple carriers..............371
Annex.................................................................................................. 375
A List of abbreviations..........................................................................375
List of Commands (GSM).................................................................. 377
Index....................................................................................................387
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Contents
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R&S®FSW-K10
1 Documentation overview
1.1 Getting started manual
Documentation overview
Service manual
This section provides an overview of the R&S FSW user documentation. Unless specified otherwise, you find the documents on the R&S FSW product page at:
www.rohde-schwarz.com/manual/FSW
Introduces the R&S FSW 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. Includes the contents of the getting started manual.
●
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 FSW is not
included.
The contents of the user manuals are available as help in the R&S FSW. 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.
https://gloris.rohde-schwarz.com
Deals with security issues when working with the R&S FSW 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 FSW. 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/FSW
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/FSW
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/FSW
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R&S®FSW-K10
2 Welcome to the GSM application
Welcome to the GSM application
Starting the GSM application
The R&S FSW-K10 is a firmware application that adds functionality to perform GSM
measurements to the R&S FSW.
The R&S FSW-K10 features:
●
Measurements on downlink or uplink signals according to the Third Generation
Partnership Project (3GPP) standards for GSM/EDGE, EDGE Evolution (EGPRS2)
and Voice services over Adaptive Multi-user Channels on One Slot (VAMOS)
●
Measurement in time, frequency or I/Q domains
●
Measurements of mobile devices (MS), single carrier and multicarrier base transceiver stations (BTS)
●
Measurement of signals ith GMSK, AQPSK, QPSK, 8PSK, 16QAM and 32QAM
modulation, normal or higher symbol rate
●
Measurement of signals using different Tx filters (e.g. narrow and wide pulse)
●
Measurements for Power vs Time, "Modulation Accuracy" and Modulation and
Transient Spectrum as required in the standard
●
Measurements of wideband noise and intermodulation products in multicarrier
operation (as defined in 3GPP TS 51.021, chapter 6.12)
●
Measurements of wideband noise, narrowband noise, and intermodulation products in multicarrier operation (as defined in 3GPP TS 51.021, chapter 6.12)
This user manual contains a description of the functionality that the application provides, including remote control operation.
General R&S FSW functions
The application-independent functions for general tasks on the R&S FSW are also
available for GSM measurements and are described in the R&S FSW 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
http://www.rohde-schwarz.com/product/FSW.html.
Installation
You can find detailed installation instructions in the R&S FSW Getting Started manual
or in the Release Notes.
2.1 Starting the GSM application
GSM measurements are performed in a separate application on the R&S FSW.
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R&S®FSW-K10
Welcome to the GSM application
Understanding the display information
To activate the GSM application
1. Select the [MODE] key.
A dialog box opens that contains all operating modes and applications currently
available on your R&S FSW.
2. Select the "GSM" item.
The R&S FSW opens a new measurement channel for the GSM application.
The measurement is started immediately with the default settings. It can be configured
in the GSM "Overview" dialog box, which is displayed when you select the "Overview"
softkey from any menu (see Chapter 6.3.1, "Configuration overview", on page 88).
Remote command:
INSTrument[:SELect] on page 191
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 channel can be active at any time. However, in order to perform the configured measurements consecutively, a Sequencer function is provided.
When the Sequencer is 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
the individual channels are updated in the tabs as the measurements are performed.
Sequential operation itself is independent of the currently displayed tab.
See also the note on using the Sequencer function in MSRA operating mode in Chap-
ter 5.18, "GSM in MSRA operating mode", on page 82.
For details on the Sequencer function see the R&S FSW User Manual.
symbol in the tab label. The result displays of
2.2 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 GSM application
Understanding the display information
1
6
5
1 = Channel bar for firmware and measurement settings
2+6 = Window title bar with diagram-specific (trace) information
3 = Diagram area
4 = Diagram footer with diagram-specific information, depending on measurement
5 = Instrument status bar with error messages, progress bar and date/time display
MSRA operating mode
In MSRA operating mode, additional tabs and elements are available. An orange background behind the measurement channel tabs indicates that you are in MSRA operating mode.
For details on the MSRA operating mode see Chapter 5.18, "GSM in MSRA operating
mode", on page 82 and the R&S FSW MSRA User Manual.
2
3
4
Channel bar information
In the GSM application, the R&S FSW shows the following settings for the default I/Q
measurement:
Table 2-1: Information displayed in the channel bar in the GSM application for the default I/Q mea-
surement
Ref Level Reference level
(m.+el.) Att Mechanical and electronic RF attenuation
Offset Reference level offset (if available)
Freq / ARFCN Center frequency for the GSM signal / Absolute Radio Frequency Channel
Number (if available)
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Welcome to the GSM application
Understanding the display information
Device / Band Device type and frequency band used by the DUT as defined in the Signal
description settings
Slot Scope Minimized visualization of the frame configuration and slots to be mea-
sured (see Chapter 5.7, "Defining the scope of the measurement",
on page 53)
SGL The sweep is set to single sweep mode.
Count Number of frames already evaluated / Total number of frames required for
statistical evaluation (Statistic Count)
(For Statistic Count > 1)
TRG Trigger source (if not "Free Run") and used trigger bandwidth (for IF, RF,
IP power triggers) or trigger offset (for external triggers)
MCWN measurement
For the MCWN measurement, the R&S FSW shows the following settings:
Table 2-2: Information displayed in the channel bar in the GSM application for the MCWN measure-
Ref Level Reference level
(m.+el.) Att Mechanical and electronic RF attenuation
Offset Reference level offset (if available)
Carriers Number of active carriers
Device / Band Device type and frequency band used by the DUT as defined in the Signal
Ref Meas Carrier used for reference measurement (if enabled)
SGL The sweep is set to single sweep mode
Count Value of the current average count / Total average count for noise mea-
TRG Trigger source (if not "Free Run") and used trigger bandwidth (for IF, RF,
ment
description settings
surement
(Noise Average Count)
IP power triggers) or trigger offset (for external triggers)
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 settings). This information is displayed only
when applicable for the current application. For details see the R&S FSW Getting Started manual.
Window title bar information
For each diagram, the header provides the following information:
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R&S®FSW-K10
Welcome to the GSM application
Understanding the display information
4
1 2
Figure 2-1: Window title bar information in the Pulse application
1 = Window number
2 = Window type
3 = Trace color
4 = Trace number
6 = Trace mode
3
5
Diagram footer information
The diagram footer (beneath the diagram) contains the start and stop values for the
displayed time, frequency or symbol 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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R&S®FSW-K10
3 About the measurement
About the measurement
A basic GSM measurement in the R&S FSW GSM application includes a power vs
time and a spectrum measurement, as well as modulation accuracy (e.g. EVM, phase
error) for a GSM signal as defined by the relevant 3GPP standards. The I/Q data from
the GSM signal applied to the RF input of the R&S FSW is captured for a specified
measurement time. This data is demodulated and synchronized with a reference signal
to identify the individual frames and slots. The slots of interest are then analyzed in
order to display the spectral and power results either graphically or numerically, and to
calculate the modulation parameters.
The standard distinguishes between single-slot and multi-slot measurements. Singleslot measurements analyze one slot - referred to as the "Slot to measure" - within the
GSM frame (which consists of 8 slots in total). Modulation-specific parameters such as
the phase error, EVM, or spectrum due to modulation are determined on a per-slot
basis. Multi-slot measurements, on the other hand, analyze a slot scope of up to 8 consecutive slots, each of which has different burst modulation characteristics. Power vs
time limit checks and the transient spectrum measurements, for example, are determined for multiple slots.
Statistical evaluation of several measurements is also possible. Finally, the GSM measurement results can be exported to other applications.
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4 Measurements and result displays
Measurements and result displays
GSM I/Q measurement results
The R&S FSW GSM application provides two different measurements in order to determine the parameters described by the GSM specifications.
The default GSM I/Q measurement captures the I/Q data from the GSM signal. The
I/Q data includes magnitude and phase information, which allows the R&S FSW GSM
application to demodulate signals and determine various characteristic signal parameters such as the modulation accuracy, power vs time, modulation and transient spectrum in just one measurement.
For multicarrier measurements, some parameters required by the GSM standard
require a frequency sweep with varying resolution bandwidths. Thus, a new separate
measurement is provided by the R&S FSW GSM application to determine the wideband noise in multicarrier measurement setups.
For details on selecting measurements see "Selecting the measurement type"
on page 85.
● GSM I/Q measurement results................................................................................17
● Multicarrier wideband noise measurements............................................................34
4.1 GSM I/Q measurement results
The I/Q data that was captured by the default GSM ("Modulation Accuracy", etc.) measurement can be evaluated using different methods. All evaluation methods available
for the GSM measurements are displayed in the selection bar in SmartGrid mode.
To activate SmartGrid mode, do one of the following:
●
Select the "SmartGrid" icon from the toolbar.
●
Select the "Display" button in the configuration "Overview".
●
Select the "Display Config" softkey from the [MEAS CONFIG] menu.
●
Press the [MEAS] key.
For details on working with the SmartGrid see the R&S FSW Getting Started manual.
By default, the GSM measurement results for I/Q measurements are displayed in the
following windows:
●
Magnitude Capture
●
PvT Full Burst
●
Modulation Accuracy
●
Power vs Slot
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Measurements and result displays
GSM I/Q measurement results
The following evaluation methods are available for GSM I/Q measurements:
Constellation................................................................................................................. 18
EVM.............................................................................................................................. 18
Magnitude Capture........................................................................................................19
Magnitude Error............................................................................................................ 20
Marker Table................................................................................................................. 20
Modulation Accuracy.....................................................................................................21
Modulation Spectrum Graph......................................................................................... 23
Modulation Spectrum Table...........................................................................................24
Phase Error...................................................................................................................26
Power vs Slot................................................................................................................ 27
PvT Full Burst................................................................................................................28
Transient Spectrum Graph............................................................................................29
Transient Spectrum Table............................................................................................. 30
Trigger to Sync Graph...................................................................................................32
Trigger to Sync Table.................................................................................................... 33
Constellation
The complex source signal is displayed as an X/Y diagram. The application analyzes
the specified slot over the specified number of bursts.
Remote command:
LAY:ADD? '1',RIGH,CONS, see LAYout:ADD[:WINDow]? on page 271
EVM
Displays the error vector magnitude over time for the Slot to Measure.
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Measurements and result displays
GSM I/Q measurement results
Remote command:
LAY:ADD:WIND '2',RIGH,ETIMe see LAYout:ADD[:WINDow]? on page 271
Results:
TRACe<n>[:DATA]? on page 293
Magnitude Capture
Displays the power vs. time trace of the captured I/Q data.
Pre-trigger samples are not displayed.
The analyzed slot scopes (1 to 8 slots of a single GSM frame) are indicated by a green
bar, the Slot to Measure in each frame by a blue bar at the bottom of the diagram.
For details see Chapter 5.7, "Defining the scope of the measurement", on page 53.
For negative trigger offsets, the trigger is displayed as a vertical red line labeled "TRG".
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Measurements and result displays
GSM I/Q measurement results
Remote command:
LAY:ADD:WIND '2',RIGH,MCAP see LAYout:ADD[:WINDow]? on page 271
Results:
FETCh:MCAPture:SLOTs:SCOPe? on page 301
FETCh:MCAPture:SLOTs:MEASure? on page 300
TRACe<n>[:DATA]? on page 293
Magnitude Error
Displays the magnitude error over time for the Slot to Measure.
Remote command:
LAY:ADD:WIND '2',RIGH,MERR see LAYout:ADD[:WINDow]? on page 271
Results:
TRACe<n>[:DATA]? on page 293
Marker Table
Displays a table with the current marker values for the active markers.
This table is displayed automatically if configured accordingly.
(See "Marker Table Display" on page 166).
Tip: To navigate within long marker tables, simply scroll through the entries with your
finger on the touchscreen.
Remote command:
LAY:ADD? '1',RIGH, MTAB, see LAYout:ADD[:WINDow]? on page 271
Results:
CALCulate<n>:MARKer<m>:X on page 341
CALCulate<n>:MARKer<m>:Y? on page 341
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Measurements and result displays
GSM I/Q measurement results
Modulation Accuracy
Displays the numeric values of the fundamental modulation characteristics of the signal
to be analyzed in the vector (I/Q) domain: error vector magnitude ("EVM"), magnitude
and phase error, IQ imbalance, etc.
The following modulation parameters are determined:
Table 4-1: Modulation accuracy parameters
Parameter
"EVM" Error vector magnitude for the Slot to Measure
Mag Error Magnitude error for the Slot to Measure
"Phase
Error"
Origin Offset Suppression
[dB]
Description SCPI query for result value
RMS and peak error values for the current frame, in percent
95%ile: error value (in percent) below which 95% of all
"EVM" results for all frames in entire measurement fall
RMS and peak error values for the current frame, in percent
95%ile: error value (in percent) below which 95% of all
"Magnitude Error" results for all frames in entire measurement fall
Phase error for the Slot to Measure
RMS and peak error values for the current frame, in percent
95%ile: error value (in percent) below which 95% of all
"Phase Error" results for all frames in entire measurement
fall
Origin offset suppression for the demodulated signal in the
Slot to Measure; Indicates the suppression of the DC carrier;
the higher the suppression, the better the DUT
READ:BURSt[:MACCuracy][:EVM]:PEAK:
<Resulttype>?
READ:BURSt[:MACCuracy][:EVM]:RMS:
<Resulttype>?
READ:BURSt[:MACCuracy]PERCentile:EVM?
READ:BURSt[:MACCuracy]:MERRor:PEAK:
<Resulttype>?
READ:BURSt[:MACCuracy]:MERRor:RMS:
<Resulttype>?
READ:BURSt[:MACCuracy]PERCentile:MERRor?
READ:BURSt[:MACCuracy]:PERRor:PEAK:
<Resulttype>?
READ:BURSt[:MACCuracy]:PERRor:RMS:
<Resulttype>?
READ:BURSt[:MACCuracy]PERCentile:PERRor?
READ:BURSt[:MACCuracy]:OSUPpress:
<Resulttype>?
I/Q Offset
[%]
I/Q offset for the demodulated signal in the Slot to Measure
READ:BURSt[:MACCuracy]:IQOFfset:
<Resulttype>?
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Measurements and result displays
GSM I/Q measurement results
Parameter
I/Q Imbalance
[%]
Frequency
Error
[Hz]
Burst
Power
[dBm]
Amplitude
Droop
[dB]
Description SCPI query for result value
A measure for gain imbalances and quadrature errors
between the inphase and quadrature components of the signal.
Frequency error of the center frequency currently measured
in the Slot to Measure
Average power measured in the slot
Indicates how much the amplitude decreases over a measured slot
The R&S FSW GSM application also performs statistical evaluation over a specified
number of results (see "Statistic Count" on page 119). To do so, the same slot is evaluated in multiple frames, namely in the number specified by the "Statistic Count". The
default value is 200 in accordance with the GSM standard.
For each parameter, the following results are displayed:
Table 4-2: Calculated summary results
READ:BURSt[:MACCuracy]:IQIMbalance:
<Resulttype>?
READ:BURSt[:MACCuracy]:FERRor:
<Resulttype>?
READ:BURSt[:MACCuracy]:BPOWer:
<Resulttype>?
READ:BURSt[:MACCuracy]:ADRoop:
<Resulttype>?
Result
type
Current Value for currently measured frame only
Average Linear average value of "Current" results from the specified
Peak Maximum value of "Current" results from specified number of
Std Dev Standard deviation of "Current" results for specified number
Description SCPI query for result value
number of frames
Exception: The average of the "Origin Offset Suppression"
is the linear average of the power ratio, converted to dBm
subsequently
frames
Exception: The peak of the "Origin Offset Suppression" is
the minimum value, as this represents the worst case, which
needs to be detected
of frames
Remote command:
LAY:ADD:WIND '2',RIGH,MACC see LAYout:ADD[:WINDow]? on page 271
Results:
READ:BURSt[:MACCuracy]:ALL? on page 304
Chapter 11.8.4, "Modulation accuracy results", on page 301
READ:BURSt[:MACCuracy]:<Parameter>:
CURRent?
READ:BURSt[:MACCuracy]:<Parameter>:
AVERage?
READ:BURSt[:MACCuracy]:<Parameter>:
MAXimum?
READ:BURSt[:MACCuracy]:<Parameter>:
SDEViation?
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Measurements and result displays
GSM I/Q measurement results
Modulation Spectrum Graph
The modulation spectrum evaluates the power vs frequency trace of a certain part of
the burst (50 to 90 % of the useful part, excluding the training sequence TSC) by measuring the average power in this part over several frames at certain fixed frequency offsets.
The "Modulation Spectrum Graph" displays the measured power levels as a trace
against the frequencies.
The measured values can be checked against defined limits; the limit lines are indicated as red lines in the diagram. The result of the limit check ("PASS"/"FAIL") are shown
at the top of the diagram.
Note: The GSM standards define both absolute and relative limits for the spectrum.
The limit check is considered to fail if both limits are exceeded.
Note: The graphical results only provide an overview of the spectrum. For a detailed
conformance check of the DUT to the GSM standard, use the "Modulation Spectrum
Table" evaluation, which uses the 5-pole filter required by the 3GPP standard.
The numeric results of the modulation spectrum evaluation are displayed in the "Modu-
lation Spectrum Table" on page 24.
The following default settings are used for a "Modulation Spectrum" evaluation.
Table 4-3: Default settings for a "Modulation Spectrum" evaluation
Setting Default
Measurement Scope The slot selected as Slot to Measure
Averaging Configuration Number of bursts as selected in Statistic Count
Limit Check According to standard: Limit check of average (Avg) trace
See Chapter 5.14.1, "Limit check for modulation spectrum", on page 68
Note: Modulation RBW at 1800 kHz.
For the "Modulation Spectrum Graph" both the RBW and VBW are set to 30 kHz.
Remote command:
LAY:ADD:WIND '2',RIGH,MSFD see LAYout:ADD[:WINDow]? on page 271
Results:
TRACe<n>[:DATA]? on page 293
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GSM I/Q measurement results
CALCulate<n>:LIMit<k>:FAIL? on page 327
CALCulate<n>:LIMit<li>:UPPer:DATA? on page 329
CALCulate<n>:LIMit<li>:CONTrol:DATA? on page 327
Modulation Spectrum Table
The modulation spectrum evaluates the power vs frequency trace of a certain part of
the burst (50 to 90 % of the useful part, excluding the training sequence TSC) by measuring the average power in this part over several frames.
The "Modulation Spectrum Table" displays the measured power levels and their offset
to the limits defined by the standard as numeric results.
Note: The GSM standards define both absolute and relative limits for the spectrum.
The limit check is considered to fail if both limits are exceeded.
Values that exceed both limits are indicated by red characters and an asterisk (*) next
to the value, and a negative "Δ to Limit" value.
Note: The graphical results of the modulation spectrum evaluation are displayed in the
"Modulation Spectrum Graph" on page 23.
The following values are displayed:
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Table 4-4: Modulation spectrum results
Result Description
Offset [kHz] Fixed frequency offsets (from the center frequency) at which power is measured
Power Negative
Offsets
Power Positive
Offsets
Table 4-5: Frequencies and filter bandwidths in modulation spectrum measurements
Offset Frequency (kHz) RBW (kHz) VBW (kHz)
± 100 30 30
± 200 30 30
± 250 30 30
± 400 30 30
± 600 30 30
Power at the frequency offset to the left of the center frequency
Levels are provided as:
[dB]: relative power level
[dBm]: absolute power level
Δ to Limit: power difference to limit defined in standard; negative values indicate the
power exceeds at least one of the limits
Power at the frequency offset to the right of the center frequency
Levels are provided as:
[dB]: relative power level
[dBm]: absolute power level
Δ to Limit: power difference to limit defined in standard; negative values indicate the
power exceeds at least one of the limits
± 800 30 30
± 1000 30 30
± 1200 30 30
± 1400 30 30
± 1600 30 30
± 1800 30 (single-carrier BTS);
100 (multi-carrier BTS);
30 (single-carrier BTS);
100 (multi-carrier BTS);
Note: "Normal" vs "Wide" Modulation Spectrum measurements.
In previous Rohde & Schwarz signal and spectrum analyzers, both a "normal" and a
"wide" modulation spectrum were available for GSM measurements. In the R&S FSW
GSM application, only one evaluation is provided. The frequency range of the frequency list, however, can be configured to be "wider" or "narrower" (see "Modulation
Spectrum Table: Frequency List" on page 129). The RBW and VBW are then adapted
accordingly.
Note: RBW at 1800 kHz.
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GSM I/Q measurement results
As opposed to previous Rohde & Schwarz signal and spectrum analyzers, in which the
RBW at 1800 kHz was configurable, the R&S FSW configures the RBW (and VBW)
automatically according to the selected frequency list (see "Modulation Spectrum
Table: Frequency List" on page 129). For the "Modulation Spectrum Graph" both the
RBW and VBW are set to 30 kHz. For the "Modulation Spectrum Table", they are set
according to Table 4-6, depending on the measured Device Type and the number of
active carriers as defined in the "Signal Description" settings.
Table 4-6: RBW settings for Modulation Spectrum Table measurements according to standard
Offset Single-carrier BTS Multicarrier BTS
(N=1)
< 1.8 MHz
1.8 MHz
> 1.8 MHz
1) See 3GPP TS 51.021 § 6.5.1.2 c) d)
2) See 3GPP TS 51.021 § 6.12.2
3) See 3GPP TS 51.021 § 6.5.1.2 f)
4) See 3GPP TS 51.010-1 § 13.4.4.2 f) and 3GPP TS45.005 § 4.2.1.3, table a1-c4
5) See 3GPP TS 51.010-1 § 13.4.4.2 d) and 3GPP TS 45.005 § 4.2.1.3
30 kHz
30 kHz
100 kHz
1)
1)
3)
30 kHz
100 kHz
100 kHz
3)
3)
3)
Multicarrier BTS
(N>1)
2)
30 kHz
100 kHz
100 kHz
2)
2)
MS mode
4)
30 kHz
100 kHz
100 kHz
Remote command:
LAY:ADD:WIND '2',RIGH,MST see LAYout:ADD[:WINDow]? on page 271
Results:
READ:SPECtrum:MODulation[:ALL]? on page 313
READ:SPECtrum:MODulation:REFerence[:IMMediate]? on page 314
Phase Error
Displays the phase error over time.
5)
5)
The following default settings are used for a "Phase Error vs Time" measurement.
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Measurements and result displays
GSM I/Q measurement results
Setting Default
Measurement Scope The slot selected as Slot to Measure
Averaging Configuration Number of frames as selected in Statistic Count
Limit Check None
Remote command:
LAY:ADD:WIND '2',RIGH,PERR see LAYout:ADD[:WINDow]? on page 271
Results:
TRACe<n>[:DATA]? on page 293
Power vs Slot
Displays the power per slot in the current frame and over all frames. The result of the
(Power vs Time) limit check is also indicated.
Note: The power is measured for inactive slots, but not for slots outside the slot scope
(see Chapter 5.7, "Defining the scope of the measurement", on page 53).
The following power values are determined:
Table 4-7: Measured power values for Power vs Slot results
Value Description SCPI query for result value
Slot Analyzed slot number in frame(s)
[0..7]
PvT Limit Power vs Time limit for the power vs time
trace of the slot, defined by the standard
Delta to
Sync
[NSP]
Power
Avg
[dBm]
The distance between the mid of the TSC
and the TSC of the Slot to Measure
NSP stands for Normal Symbol Period, i.e.
the duration of one symbol using a normal
symbol rate (approx. 3.69μs).
The measured "Delta to Sync" value has a
resolution of 0.02 NSP.
For details see Chapter 5.13, "Delta to sync
values", on page 67.
Average power in slot in current or all frames READ:BURSt:SPOWer:SLOT<Slot>:CURRent:AVERage?
READ:BURSt:SPOWer:SLOT<Slot>:LIMit:FAIL? on page 322
READ:BURSt:SPOWer:SLOT<Slot>:DELTatosync? on page 321
on page 318
READ:BURSt:SPOWer:SLOT<Slot>:ALL:AVERage? on page 316
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Value Description SCPI query for result value
Measurements and result displays
GSM I/Q measurement results
Power
Peak
[dBm]
Crest
[dB]
Maximum power in slot in current or all
frames
Crest factor in slot in current or all frames, i.e.
Power Peak / Power Avg
Remote command:
LAY:ADD:WIND '2',RIGH,PST see LAYout:ADD[:WINDow]? on page 271
Results:
Chapter 11.8.6, "Power vs slot results", on page 315
PvT Full Burst
The Power vs Time evaluation determines the power of all slots (bursts) in the selected
slot scope and performs a limit check of the power vs time trace against the specified
PvT mask.
The "PvT Full Burst" result display shows the power vs time trace, where the time axis
corresponds to the selected slot scope. The PvT mask is indicated by red lines, and
the overall result of the limit check is shown at the top of the diagram.
Note: The result of the Power vs Time limit check for individual slots is indicated in the
"Power vs Slot" on page 27 evaluation.
READ:BURSt:SPOWer:SLOT<Slot>:CURRent:MAXimum?
on page 320
READ:BURSt:SPOWer:SLOT<Slot>:ALL:MAXimum? on page 317
READ:BURSt:SPOWer:SLOT<Slot>:CURRent:CRESt?
on page 319
READ:BURSt:SPOWer:SLOT<Slot>:ALL:CRESt? on page 316
Note: Full burst refers to the fact that the entire burst is displayed, including the rising
and falling edges and the burst top. However, you can easily analyze the edges in
more detail using the zoom functions
(See the R&S FSW User Manual).
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GSM I/Q measurement results
The following default settings are used for a "Power vs Time" evaluation.
Table 4-8: Default settings for a "Power vs Time" evaluation
Setting Default
Measurement Scope The slot scope defined by First Slot to measure and Number of Slots to mea-
sure
Averaging Configuration Number of bursts as selected in Statistic Count
Limit Check According to standard:
●
The maximum (Max) trace is checked against the upper limit.
●
The minimum (Min) trace is checked against the lower limit.
See Chapter 5.14.3, "Limit check for power vs time results", on page 69
Remote command:
LAY:ADD:WIND '2',RIGH,PTF see LAYout:ADD[:WINDow]? on page 271
Results:
TRACe<n>[:DATA]? on page 293
TRACe<n>[:DATA]:X? on page 293
CALCulate<n>:LIMit<k>:FAIL? on page 327
CALCulate<n>:LIMit<li>:UPPer:DATA? on page 329
CALCulate<n>:LIMit<li>:CONTrol:DATA? on page 327
Transient Spectrum Graph
The transient spectrum is very similar to the modulation spectrum evaluation; it evaluates the power vs frequency trace by measuring the power over several frames. However, as opposed to the modulation spectrum evaluation, the entire slot scope (defined
by the Number of Slots to measure and the First Slot to measure) is evaluated in each
frame, including the rising and falling burst edges, not just the useful part in the Slot to
Measure.
Furthermore, the number of fixed frequency offsets is lower, and the peak power is
evaluated rather than the average power, as this measurement is used to determine
irregularities.
The "Transient Spectrum Graph" displays the measured power levels as a trace
against the frequencies for the specified slots.
The measured values can be checked against defined limits; the limit lines are indicated as red lines in the diagram. The result of the limit check ("PASS"/"FAIL") is shown
at the top of the diagram.
Note: The GSM standards define both absolute and relative limits for the spectrum.
The limit check is considered to fail if both limits are exceeded.
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GSM I/Q measurement results
Note: The graphical results only provide an overview of the spectrum. For a detailed
conformance check of the DUT to the GSM standard, use the "Transient Spectrum
Table" evaluation, which uses the 5-pole filter required by the 3GPP standard.
The numeric results of the modulation spectrum evaluation are displayed in the "Modu-
lation Spectrum Table" on page 24.
The following default settings are used for "Transient Spectrum" measurements.
Setting Default
Measurement Scope The slot scope defined by Number of Slots to measure and the First Slot to
measure in the "Demodulation Settings" (see Chapter 6.3.6.1, "Slot scope",
on page 121).
Averaging Configuration Number of frames as selected in Statistic Count
Limit Check Limit check of maximum (Max) trace
See Chapter 5.14.2, "Limit check for transient spectrum", on page 69
Remote command:
LAY:ADD:WIND '2',RIGH,TSFD see LAYout:ADD[:WINDow]? on page 271
Results:
TRACe<n>[:DATA]? on page 293
CALCulate<n>:LIMit<k>:FAIL? on page 327
Transient Spectrum Table
The transient spectrum evaluates the power vs frequency trace of the slot scope by
measuring the power in these slots over several frames.
For details see "Transient Spectrum Graph" on page 29.
The "Transient Spectrum Table" displays the measured power levels and their offset to
the limits defined by the standard as numeric results.
Note: The GSM standards define both absolute and relative limits for the spectrum.
The limit check is considered to fail if both limits are exceeded.
Values that exceed both limits are indicated by red characters and an asterisk (*) next
to the value, and a negative "Δ to Limit" value.
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GSM I/Q measurement results
To determine the relative limit values, a reference power is required (see "Transient
Spectrum: Reference Power" on page 129). In order to detect irregularities, it is useful
to define the peak power as a reference. However, the standard requires the reference
power to be calculated from the RMS power.
To perform the measurement according to the 3GPP standard set the reference power
to RMS and the Slot to Measure to the slot with the highest power.
See 3GPP TS 45.005, chapter "4 Transmitter characteristics ":
For GMSK modulation, the term output power refers to the measure of the power when
averaged over the useful part of the burst (see annex B).
For QPSK, AQPSK, 8-PSK, 16-QAM and 32-QAM modulation, the term "output power"
refers to a measure that, with sufficient accuracy, is equivalent to the long term average of the power when taken over the useful part of the burst as specified in 3GPP TS
45.002 with any fixed TSC and with random encrypted bits.
And 3GPP TS 51.021, chapter "6.5.2 Switching transients spectrum":
The reference power for relative measurements is the power measured in a bandwidth
of at least 300 kHz for the TRX under test for the time slot in this test with the highest
power.
Note: The graphical results of the transient spectrum evaluation are displayed in the
"Transient Spectrum Graph" on page 29.
The following values are displayed:
Table 4-9: Transient spectrum results
Result Description
Offset
[kHz]
Power Negative
Offsets
Power Positive
Offsets
Fixed frequency offsets (from the center frequency) at which power is measured
Power at the frequency offset to the left of the center frequency
Levels are provided as:
[dB]: relative power level
[dBm]: absolute power level
Δ to Limit: power difference to limit defined in standard; negative values indicate the
power exceeds at least one of the limits
Power at the frequency offset to the right of the center frequency
Levels are provided as:
[dB]: relative power level
[dBm]: absolute power level
Δ to Limit: power difference to limit defined in standard; negative values indicate the
power exceeds at least one of the limits
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Measurements and result displays
GSM I/Q measurement results
Remote command:
LAY:ADD:WIND '2',RIGH,TST see LAYout:ADD[:WINDow]? on page 271
Results:
READ:SPECtrum:SWITching[:ALL]? on page 323
READ:SPECtrum:SWITching:REFerence[:IMMediate]? on page 324
Trigger to Sync Graph
The Trigger to Sync measurement determines the time between an external trigger
event and the start of the first symbol of the TSC. The start of the first symbol of the
TSC corresponds to the time 0 of the symbol period (see Chapter 5.10, "Definition of
the symbol period", on page 59).
Only one result per data capture is provided. Therefore, it is useful to perform several
data captures and average the results to obtain an accurate value (see "Statistic
Count" on page 119).
Both graphical and numeric (table) results are available. While the graphical results are
mainly used to determine the required measurement settings, the numeric results provide the actual trigger to sync value, including statistical evaluation (see "Trigger to
Sync Table" on page 33).
The Trigger to Sync diagram shows two traces:
●
Trace1: a histogram shows the probability density function (PDF) of all measured
Trigger to Sync values. Obviously, the histogram can only provide reasonable
results if several I/Q captures are performed and considered. In an ideal case
(assuming no noise), the histogram would have a gaussian shape.
The histogram is helpful to determine the number of Trigger to Sync values to be
averaged (Statistic Count) in order to obtain the required time resolution of the
averaged Trigger to Sync value. The higher the statistic count, the closer the graph
gets to a gaussian shape, and the higher the resolution of the averaged Trigger to
Sync value becomes.
●
Trace2: the second trace is superimposed on the histogram and visualizes the
probability density function (PDF) of the average Trigger to Sync value and the
standard deviation as provided in the Trigger to Sync table. This trace helps you
judge the reliability of the averaged values in the table. The narrower this trace, the
less the individual values deviate from the averaged result. if this trace is too wide,
increase the Statistic Count.
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GSM I/Q measurement results
Note: The x-axis of the histogram indicates the individual Trigger to Sync values. Thus,
the scaling must be very small, in the range of ns. However, since the value range, in
particular the start value, of the possible results is not known, the x-axis must be adapted to the actual values after a number of measurements have taken place. This is
done using the adaptive data size setting (see "Adaptive Data Size" on page 130). This
setting defines how many measurements are performed before the x-axis is adapted to
the measured values, and then fixed to that range.
Remote command:
LAY:ADD? '1',RIGH,TGSG, see LAYout:ADD[:WINDow]? on page 271
DISPlay:WINDow:TRACe1:MODE WRITe (for Histogram, see DISPlay[:
WINDow<n>]:TRACe<t>:MODE on page 279 )
DISPlay:WINDow:TRACe2:MODE PDFavg (for PDF of average, see DISPlay[:
WINDow<n>]:TRACe<t>:MODE on page 279)
Results:
TRACe<n>[:DATA]? on page 293
TRACe<n>[:DATA]:X? on page 293
Trigger to Sync Table
The Trigger to Sync measurement determines the time between an external trigger
event and the start of the first symbol of the TSC. The start of the first symbol of the
TSC corresponds to the time 0 of the symbol period (see Chapter 5.10, "Definition of
the symbol period", on page 59).
Only one result per data capture is provided. Therefore, it is useful to perform several
data captures and average the results to obtain an accurate value (see "Statistic
Count" on page 119).
Both graphical and numeric (table) results are available. While the graphical results are
mainly used to determine the required measurement settings (see "Trigger to Sync
Graph" on page 32), the numeric results provide the actual trigger to sync value,
including statistical evaluation.
The Trigger to Sync table shows the following values:
Value Description
Current Trigger to Sync value for current measurement in μs
Average Trigger to Sync value averaged over the Statistic Count number of measurements
Min Minimum Trigger to Sync value in the previous Statistic Count number of measurements
Max Maximum Trigger to Sync value in the previous Statistic Count number of measurements
Std Dev Standard deviation of the individual Trigger to Sync values to the average value
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4.2 Multicarrier wideband noise measurements
Measurements and result displays
Multicarrier wideband noise measurements
Remote command:
LAY:ADD? '1',RIGH,TGST, see LAYout:ADD[:WINDow]? on page 271
Results:
Chapter 11.8.8, "Trigger to sync results", on page 325
The I/Q data captured by the default GSM I/Q measurement includes magnitude and
phase information, which allows the R&S FSW GSM application to demodulate signals
and determine various characteristic signal parameters such as the modulation accuracy, modulation or transient spectrum in just one measurement.
As the result of a swept measurement, on the other hand, the signal cannot be
demodulated based on the power vs. frequency trace data. Frequency sweep measurements can tune on a constant frequency ("Zero span measurement") or sweep a
frequency range ("Frequency sweep measurement").
For multicarrier measurements, the GSM standard defines limits for some parameters
concerning noise and intermodulation products. Thus, a new separate measurement is
provided by the R&S FSW GSM application: the Multicarrier Wideband Noise Mea-
surement (MCWN). This measurement comprises:
●
I/Q based measurements on the carriers to determine their power levels and reference powers
●
Frequency sweeps with RBWs of 100 kHz (to measure wideband noise) and
300 kHz (to measure intermodulation products)
●
Gated zero span measurements with an RBW of 30 kHz to measure narrowband
noise
MCWN measurements and MSRA mode
MCWN measurements are only available in Signal and Spectrum Analyzer operating
mode, not in MSRA mode (see Chapter 5.18, "GSM in MSRA operating mode",
on page 82).
For more information on MCWN measurements see also Chapter 5.16, "Multicarrier
and wideband noise", on page 71.
● Multicarrier evaluation methods.............................................................................. 34
4.2.1 Multicarrier evaluation methods
The GSM multicarrier wideband noise measurement can be evaluated using different
methods. All evaluation methods available for the measurement are displayed in the
selection bar in SmartGrid mode.
For details on working with the SmartGrid see the R&S FSW Getting Started manual.
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Measurements and result displays
Multicarrier wideband noise measurements
By default, the MWCN measurement results are displayed in the following windows:
●
Spectrum Graph
●
Carrier Power Table
The following evaluation methods are available for GSM MCWN measurements:
Spectrum Graph............................................................................................................35
Carrier Power Table...................................................................................................... 36
Inner IM Table............................................................................................................... 37
Outer IM Table...............................................................................................................38
Inner Narrow Band Table.............................................................................................. 39
Outer Narrowband Table...............................................................................................39
Inner Wideband Table................................................................................................... 41
Outer Wideband Table.................................................................................................. 42
Marker Table................................................................................................................. 44
Spectrum Graph
Displays the level results for the frequencies in the defined frequency span (typically
the Tx band).
The trace is calculated from a frequency sweep with a 100 kHz RBW and one sweep
with a 300 kHz RBW. The displayed trace is averaged over the Noise Average Count
number of noise measurements.
The narrowband noise results (if available) are indicated as vertical green bars at the
distinct measurement frequencies (see "Outer Narrowband Table" on page 39).
The results of the limit check are also indicated in the diagram (see also Chap-
ter 5.16.4, "Limit check for MCWN results", on page 75):
Table 4-10: Limit line checks
Label Possible values Description / Limit line suffix (<k>)
Limit check PASS | FAIL Overall limit check for all limit lines
Wideband Noise
(<current> exceptions)
PASS | FAIL Limit check for wideband noise (trace)
(Number of detected exceptions; provided only if exceptions
are enabled)
<k> = 1
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Measurements and result displays
Multicarrier wideband noise measurements
Label Possible values Description / Limit line suffix (<k>)
IM 100 kHz PASS | FAIL Limit check for intermodulation at 100 kHz
(Number of detected exceptions; provided only if exceptions
are enabled)
<k> = 2
IM 300 kHz PASS | FAIL Limit check for intermodulation at 300 kHz
<k> = 3
Narrowband Noise PASS | FAIL Limit check for narrowband noise
<k> = 4
Exceptions: <current>
< <maximum>
Exceptions: <current>
< <maximum>
PASS | FAIL Number of bands with exceptions in range A (currently
detected vs. maximum allowed); provided only if exceptions
are enabled
<k> = 5
PASS | FAIL Number of bands with exceptions in range B (currently
detected vs. maximum allowed); provided only if exceptions
are enabled
<k> = 6
Note: Markers are now available in the "Spectrum Graph" result display.
Remote command:
LAY:ADD? '1',RIGH,WSFDomain, see LAYout:ADD[:WINDow]? on page 271
Results:
TRACe:DATA? TRACe1, see TRACe<n>[:DATA]? on page 293
Limit results:
FETCh:SPECtrum:MODulation:LIMit:FAIL? on page 332
CALCulate<n>:LIMit<k>:FAIL? on page 327
CALCulate<n>:LIMit<li>:CONTrol:DATA? on page 327
CALCulate<n>:LIMit<li>:UPPer:DATA? on page 329
CALCulate<n>:LIMit<k>:EXCeption:COUNt:CURR? on page 330
CALCulate<n>:LIMit<k>:EXCeption:COUNt:MAX? on page 331
Carrier Power Table
Displays the measured power levels and reference powers of all active carriers.
The following parameters are shown:
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Measurements and result displays
Multicarrier wideband noise measurements
Table 4-11: Carrier power measurement results
Parameter Description
Carrier No. Active carrier number (as defined in Chapter 6.3.2.4, "Carrier settings",
on page 97).
Additional labels:
●
"max": the carrier with the highest power level
(If the reference power is determined by a reference measurement (see
"Enabling a reference power measurement (Measure)" on page 157),
and automatic carrier selection is active, see "Carrier Selection/Carrier"
on page 157.)
●
"ref": selected carrier for reference power
(If the reference power is determined by a reference measurement (see
"Enabling a reference power measurement (Measure)" on page 157),
but the carrier is selected manually, see "Carrier Selection/Carrier"
on page 157.)
●
"man": manually defined reference powers (see "Defining Reference
Powers Manually" on page 157)
Carrier frequency Frequency of the carrier at which power was measured
Power level Measured power level in dBm
Reference power with RBW
300 kHz
Reference power with RBW
100 kHz
Reference power with RBW
30 kHz
Reference power for measurement with 300 kHz RBW (or manually defined
reference value)
Reference power for measurement with 100 kHz RBW (or manually defined
reference value)
Reference power for measurement with 30 kHz RBW (or manually defined
reference value)
Remote command:
LAY:ADD? '1',RIGH,WSRP, see LAYout:ADD[:WINDow]? on page 271
Results:
FETCh:WSPectrum:REFerence:POWer[:ALL]? on page 336
Inner IM Table
Similar to the Outer IM Table, but the measured intermodulation products (up to the
order specified in Intermodulation) for the frequencies in the gap between the GSM
carrier blocks for non-contiguous carrier allocation are displayed. The frequency offsets
are defined as offsets from the closest carrier, i.e. the uppermost carrier of the lower
sub-block and the lowermost carrier of the upper sub-block.
Figure 4-1: Inner and outer intermodulation
The rows are sorted in ascending order of the absolute IM frequency.
For contiguous carrier allocation or if Intermodulation is "off", this table is empty.
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Measurements and result displays
Multicarrier wideband noise measurements
Remote command:
LAY:ADD? '1',RIGH,IIMP, see LAYout:ADD[:WINDow]? on page 271
Results:
FETCh:WSPectrum:IMPRoducts:INNer[:ALL]? on page 332
Outer IM Table
Displays the measured intermodulation products (up to the order specified in Intermo-
dulation) for the frequencies outside of the sub-blocks (but not in the gap).
For each of the following regions the parameters described in Table 4-12 are shown:
●
frequencies to the left of the lowermost carrier
●
frequencies to the right of the uppermost carrier
The rows are sorted in ascending order of the absolute IM frequency.
The frequency offsets are defined as offsets from the closest carrier, i.e. the lowermost
carrier of the lower sub-block and the uppermost carrier of the upper sub-block.
Figure 4-2: Inner and outer intermodulation
The following parameters are shown:
Table 4-12: Intermodulation results
Result Description
Offset [MHz] Frequency offsets (from the closest carrier) at which intermodulation power is measured
Freq [MHz] Absolute frequency of intermodulation product
Order Order of intermodulation product
RBW [kHz] Resolution bandwidth used for measurement
dB relative power level (to reference power) measured at IM frequency
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Measurements and result displays
Multicarrier wideband noise measurements
Result Description
dBm absolute power level measured at IM frequency
Δ to Limit: power difference to limit defined in standard (negative values indicate: limit check failed)
If Intermodulation is "off", this table is empty.
Remote command:
LAY:ADD? '1',RIGH,OIMP, see LAYout:ADD[:WINDow]? on page 271
Results:
FETCh:WSPectrum:IMPRoducts:OUTer[:ALL]? on page 333
Inner Narrow Band Table
Similar to the Outer Narrowband Table, however the measured distortion products in
the gap between the GSM carrier blocks are displayed for non-contiguous carrier allo-
cation.
The frequency offsets are defined as offsets from the closest carrier, i.e. the uppermost
carrier of the lower sub-block and the lowermost carrier of the upper sub-block. Offsets
are lower than 1.8 MHz (400 KHz, 600 KHz, 1200 KHz).
The rows are sorted in ascending order of the absolute measurement frequency.
For contiguous carrier allocation or if narrowband noise measurement is disabled, this
table is empty.
Remote command:
LAY:ADD? '1',RIGH,INAR, see LAYout:ADD[:WINDow]? on page 271
Results:
FETCh:WSPectrum:NARRow:INNer[:ALL]? on page 334
Outer Narrowband Table
Displays the measured distortion products for the frequencies outside of the subblocks
(but not in the gap) for non-contiguous carrier allocation.
The measurement is gated according to the standard (50 to 90 % of the useful part of
the time slot excluding the mid amble, in the outermost carriers). If no bursts are found
a warning is issued in the status bar and the measurement results are not valid.
The limits are calculated by cumulating the individual limit lines of each active carrier.
Frequencies falling onto theoretical intermodulation products receive an extra relaxation.
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Measurements and result displays
Multicarrier wideband noise measurements
For each of the following regions the parameters described in Narrowband noise
results are shown:
●
frequencies to the left of the lowermost carrier
●
frequencies to the right of the uppermost carrier
The rows are sorted in ascending order of the absolute measurement frequency.
The frequency offsets are defined as offsets from the closest carrier, i.e. the lowermost
carrier of the lower sub-block and the uppermost carrier of the upper sub-block.
For Narrow Band Noise measurements the frequency offsets are lower than 1.8 MHz
(400 kHz, 600 kHz, 1200 kHz).
Outer Narrow Band Noise results are shown for contiguous AND for non-contiguous
carrier allocation.
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Measurements and result displays
Multicarrier wideband noise measurements
Figure 4-3: Narrowband noise results
The following parameters are shown:
Table 4-13: Narrowband noise results
Result Description
Offset [MHz] Frequency offsets (from the closest carrier) at which distortion power is measured
Freq [MHz] Absolute frequency of distortion product
RBW [kHz] Resolution bandwidth used for measurement
dB Relative power level (to reference power) measured at the distortion frequency
dBm Absolute power level measured at distortion frequency
Δ to Limit: Power difference to limit defined in standard (negative values indicate: limit check failed)
If narrowband measurement is disabled, this table is empty.
Remote command:
LAY:ADD? '1',RIGH,ONAR, see LAYout:ADD[:WINDow]? on page 271
Results:
FETCh:WSPectrum:NARRow:OUTer[:ALL]? on page 335
Inner Wideband Table
Similar to the Outer Wideband Table, but the numeric results of the wideband noise
measurement in the gap between the GSM carrier blocks for non-contiguous carrier
allocation are displayed. The frequency offsets are defined as offsets from the closest
carrier, i.e. the uppermost carrier of the lower sub-block and the lowermost carrier of
the upper sub-block.
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Measurements and result displays
Multicarrier wideband noise measurements
As for the Outer Wideband Table, the "Inner Wideband Table" normally has one entry
for every limit line segment the GSM standard (3GPP TS 51.021) defines in section
6.5.1. But in this table, the middle of the gap between the 2 sub-blocks is used to split
up the results in an upper and lower part (see ranges C and D in Figure 4-4).
Figure 4-4: Inner and outer wideband noise results
The rows are sorted in ascending order of the absolute frequencies of the wideband
noise measurement segments.
For contiguous carrier allocation or if noise measurement is disabled, this table is
empty. Furthermore, the table may be empty in the following cases:
●
The gap is too small (<3.6 MHz = twice the minimum offset of 1.8 MHz).
●
Intermodulation measurement overrides wideband noise measurement: Around
every calculated intermodulation product frequency inside or outside the gap, the
R&S FSW GSM application places an intermodulation measurement range of a
certain bandwidth (regardless whether intermodulation measurement is enabled or
not). Due to their more relaxed limits, the IM measurement wins over the wideband
noise measurement. Thus, many overlapping IM ranges can narrow down the
wideband noise measurement segment until it is eliminated. You can check this by
activating only intermodulation (IM order 3 and 5!) OR only wideband measure-
ment and determining where a limit line is drawn and where there are none.
Remote command:
LAY:ADD? '1',RIGH,IWID, see LAYout:ADD[:WINDow]? on page 271
Results:
FETCh:WSPectrum:WIDeband:INNer[:ALL]? on page 337
Outer Wideband Table
Displays the numeric results of the wideband noise measurement for the frequencies
outside of the sub-blocks (but not in the gap). Measurement offsets relative to outermost carriers are always greater than 1.8 MHz.
Note: The results for the gap are displayed in the Inner Wideband Table.
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Measurements and result displays
Multicarrier wideband noise measurements
For each of the following regions the parameters described in Wideband noise results
are shown:
●
frequencies to the left of the lowermost carrier
●
frequencies to the right of the uppermost carrier
The wideband noise tables divide the total frequency range of the wideband noise
measurement (defined by the selected span and the GSM band) in non-overlapping
frequency segments. (For details see Chapter 5.16.6, "Wideband noise measurement",
on page 80.)
The following parameters are shown for wideband noise tables for each segment:
Table 4-14: Wideband noise results
Result Description
Start [MHz] Absolute start frequency of segment
Stop [kHz] Absolute stop frequency of segment
Offset [MHz] Frequency of the worst measured wideband noise result in that segment. Relative to the
nearest active outermost carrier
Freq [MHz] Absolute frequency of the worst measured wideband noise result in that segment.
dB Relative power level (to reference power) of the worst measured wideband noise result in
that segment
dBm Absolute power level of the worst measured wideband noise result in that segment
Δ to Limit: Worst power difference to limit defined in standard in that segment. Defined exceptions
are considered.
(Negative values indicate: limit check failed)
The rows are sorted in ascending order of the absolute frequencies of the wideband
noise measurement segments.
If noise measurement is disabled, this table is empty. Furthermore, the table may be
empty in the following cases:
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Measurements and result displays
Multicarrier wideband noise measurements
●
The span is too small. Wideband noise measurement cannot start closer than
1.8 MHz from the outermost carriers and ends 10 MHz outside the edge of the rel-
evant transmit band. This measurement range may be restricted further by the
defined measurement span (see Chapter 6.4.4.2, "Frequency settings",
on page 141). For a measurement according to standard, set the span to the TX
band automatically (see "Setting the Span to Specific Values Automatically"
on page 143).
●
Intermodulation measurement overrides wideband noise measurement: Around
every calculated intermodulation product frequency inside or outside the gap, the
R&S FSW GSM application places an intermodulation measurement range of a
certain bandwidth (regardless whether intermodulation measurement is enabled or
not). Due to their more relaxed limits, the IM measurement wins over the wideband
noise measurement. Thus, many overlapping IM ranges can narrow down the
wideband noise measurement segment until it is eliminated. You can check this by
activating only intermodulation (IM order 3 and 5!) OR only wideband measure-
ment and determining where a limit line is drawn and where there are none.
Remote command:
LAY:ADD? '1',RIGH,OWID, see LAYout:ADD[:WINDow]? on page 271
Results:
FETCh:WSPectrum:WIDeband:OUTer[:ALL]? on page 339
Marker Table
Displays a table with the current marker values for the active markers.
This table is displayed automatically if configured accordingly.
(See "Marker Table Display" on page 166).
Tip: To navigate within long marker tables, simply scroll through the entries with your
finger on the touchscreen.
Remote command:
LAY:ADD? '1',RIGH, MTAB, see LAYout:ADD[:WINDow]? on page 271
Results:
CALCulate<n>:MARKer<m>:X on page 341
CALCulate<n>:MARKer<m>:Y? on page 341
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5 Basics on GSM measurements
5.1 Relevant digital standards
Basics on GSM measurements
Short introduction to GSM (GMSK, EDGE and EDGE evolution)
Some background knowledge on basic terms and principles used in GSM measurements is provided here for a better understanding of the required configuration settings.
The measurements and the physical layer – the layer of the GSM network on which
modulation, transmission of RF signals, reception of RF signals, and demodulation
take place – is defined in the standards:
Table 5-1: GSM standards
3GPP TS 45.004 Details on Modulation
3GPP TS 45.005 General measurement specifications and limit values
3GPP TS 45.010 Details on Synchronization and Timing
3GPP TS 51.010 Detailed measurement specifications and limit values for mobile stations (MS)
3GPP TS 51.021 Detailed measurement specifications and limit values for base transceiver stations
(BTS)
5.2 Short introduction to GSM (GMSK, EDGE and EDGE evolution)
The GSM (Global System for Mobile Communication) standard describes the GSM
mobile radio network that is in widespread use today. In a first step to enhance this network, 8PSK modulation has been defined in addition to the existing GMSK (Gaussian
Minimum Shift Keying) modulation. With 8PSK, the mobile or base station operates in
the EDGE mode. While the 8PSK modulation transmits 3 bits within a symbol, GMSK
can only transmit 1 bit within a symbol.
In a second step to enhance this network, higher symbol rate (HSR), QPSK, 16QAM,
and 32QAM modulation, narrow and wide pulse shapes for the Tx filter have been
defined. Here, EDGE Evolution and EGPRS2 are synonyms for this second enhancement.
This means that GSM includes different modes: GMSK, EDGE and EDGE Evolution.
The terms EDGE and EDGE Evolution are used here only when there are significant
differences between the modes. In all other cases, the term GSM is used.
Time domain vs frequency domain
A TDMA (Time Division Multiple Access) and FDMA (Frequency Division Multiple
Access) scheme is used to transfer data in the GSM network. This means that the digital information is transmitted discretely in the time domain (mainly used to distinguish
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Basics on GSM measurements
Short introduction to GSM (GMSK, EDGE and EDGE evolution)
between different users) as well as in the frequency domain (mainly used to distinguish
between BTS).
Slots and frames
The time domain is divided into slots with a duration of 576.923 µs (exactly: 3/5200 s).
8 slots (numbered 0 to 7) are combined into 1 frame with a duration of approximately
4.6154 ms (exactly: 3/650 s).
Multiframes and superframes
Frames can be grouped into a multiframe consisting of either 26 (for support traffic and
associated control channels) or 51 (for all other purposes) frames. Multiframes can be
grouped to superframes consisting of either 51 26-frame or 26 51-frame multiframes.
Multiframes and superframes are not of relevance for the physical measurements on
the GSM system and thus not discussed in detail here.
A mobile phone, therefore, does not communicate continuously with the base station;
instead, it communicates discretely in individual slots assigned by the base station during connection and call establishment. In the simplest case, 8 mobiles share the 8 slots
of a frame (TDMA).
Frequency bands and channels
The frequency range assigned to GSM is divided into frequency bands, and each
band, in turn, is subdivided into channels.
Each frequency channel is identified by its center frequency and a number, known as
the ARFCN (Absolute Radio Frequency Channel Number), which identifies the frequency channel within the specific frequency band. The GSM channel spacing is 200
kHz.
Communication between a mobile and a base station can be either frequency-continuous or frequency-discrete – distributed across various frequency channels (FDMA). In
the standard, the abbreviation "SFH" (slow frequency hopping) is used to designate the
latter mode of communication.
Uplink and downlink
Base stations and mobiles communicate in different frequency ranges; the mobile
sends in the "uplink" (UL), and the base station in the "downlink" (DL).
The frequencies specified in the standard plus their channel numbers (ARFCN) are
shown in the figure and table below.
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Basics on GSM measurements
Short introduction to GSM (GMSK, EDGE and EDGE evolution)
Figure 5-1: The frequencies specified in the GSM standard
Table 5-2: Frequencies and channel numbers (ARFCN) in the GSM standard
Band Class UL
[MHz]
Freq. DL
[MHz]
Freq. Freq.
Middle
Band UL-DL Shift ARFCN
Lower Upper Lower Upper UL DL Range 1 Range 2
T-GSM 380 380.2 389.8 390.2 399.8 385.0 395.0 10 MHz
T-GSM 410 410.2 419.8 420.2 429.8 415.0 425.0 10 MHz
0 … 48
0 … 48
1)
1)
–
–
GSM 450 450.4 457.6 460.4 467.6 454.0 464.0 10 MHz 259 … 293 –
GSM 480 478.8 486.0 488.8 496.0 482.4 492.4 10 MHz 306 … 340 –
GSM 710 698.0 716.0 728.0 746.0 707.0 737.0 30 MHz
0 … 90
1)
–
GSM 750 747.0 762.0 777.0 792.0 754.5 784.5 30 MHz 438 … 511 –
T-GSM 810 806.0 821.0 851.0 866.0 813.5 858.5 45 MHz
0 … 75
1)
–
GSM 850 824.0 849.0 869.0 894.0 836.5 881.5 45 MHz 128 … 251 –
P-GSM 900 890.0 915.0 935.0 960.0 902.5 947.5 45 MHz 1 … 124 –
E-GSM 900 880.0 915.0 925.0 960.0 897.5 942.5 45 MHz 0 … 124 975 … 1023
R-GSM 900 876.0 915.0 921.0 960.0 895.5 940.5 45 MHz 0 … 124 955 … 1023
T-GSM 900 870.4 876.0 915.4 921.0 873.2 918.2 45 MHz
0 … 28
1)
–
DCS 1800 1710.0 1785.0 1805.0 1880.0 1747.5 1842.5 95 MHz 512 … 885 –
PCS 1900 1850.0 1910.0 1930.0 1990.0 1880.0 1960.0 80 MHz 512 … 810 –
1)
For these frequency bands, there is no fixed ARFCN to frequency assignment, instead it is calculated with a formula taking an
OFFSET parameter which is signaled by a higher layer of the network. The given ARFCNs assume an OFFSET value of 0.
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Basics on GSM measurements
Short introduction to GSM (GMSK, EDGE and EDGE evolution)
Modulation modes
Different modulation modes are used in the GSM mobile radio network. The original
GSM modulation is GMSK, with the normal symbol rate (NSR) of approximately
270.833 ksymb/s (exactly: 1625/6 ksymb/s). This corresponds to a bit rate of 270.833
kbit/s. The details are specified in chapter 2 of "3GPP TS 45.004" (see Table 5-1).
The 8PSK (Phase Shift Keying) modulation, which is used within EDGE, was introduced to increase the data rate on the physical link. It uses the same symbol rate (the
normal symbol rate) as GMSK (270.833 ksymb/s), but has a bit rate of 3 × 270.833
kbit/s (exactly: 812.5 kbit/s).
In this method, three bits represent a symbol. The details are specified in chapter 3
"3GPP TS 45.004" (see Table 5-1).
The 16QAM and 32QAM (Quadrature Amplitude Modulation) modulation, which are
used in EDGE Evolution, were introduced to further increase the data rate on the physical link. They use the normal symbol rate (270.833 ksymb/s), but have bit rates of 4 ×
270.833 kbit/s or 5 × 270.833 kbit/s, respectively. The details are specified in chapter 4
"3GPP TS 45.004" (see Table 5-1).
The QPSK, 16QAM and 32QAM modulation with a higher symbol rate, which are used
in EDGE Evolution, were introduced to further increase the data rate on the physical
link. They use a higher symbol rate (325 ksymb/s), but have bit rates of 2 × 325 kbit/s,
4 × 325 kbit/s or 5 × 325 kbit/s, respectively. The details are specified in chapter 5
"3GPP TS 45.004" (see Table 5-1).
The figure below shows the modulation spectrum for both GMSK and 8PSK.
Figure 5-2: GMSK and 8PSK modulation spectrum
Increasing the bandwidth - multiple slots (GPRS, HSCSD)
The customers’ demand for higher telecommunication speeds increases the demand
for bandwidth. Therefore, the GSM standard has to evolve constantly. An example of
this development is the introduction of the EDGE/EDGE Evolution specification and the
GPRS/EGPRS2 and HSCSD modes.
Until now, each mobile could use only one slot per frame, but the new HSCSD (High
Speed Circuit Switched Data) and GPRS (General Packet Radio Service) methods will
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5.3 Short introduction to VAMOS
Basics on GSM measurements
Short introduction to VAMOS
allow permanent assignment of more than one slot per mobile, plus dynamic utilization
of multiple slots.
The concept behind GPRS is dynamic assignment of up to 8 slots to each mobile for
data transmission, depending on demand (and availability in the network).
HSCSD allows permanent assignment of up to 4 slots to a mobile.
Normal and higher symbol rates
The modulation modes GMSK, QPSK, 8PSK, 16QAM and 32QAM can be used with
either normal or higher symbol rate and different Tx filters.
What is significant for the R&S FSW GSM application in this respect is that the mobile
can send power on a frequency in more than one slot.
The "Voice services over Adaptive Multi-user Channels on One Slot" (VAMOS) extension to the GSM standard allows transmission of two GMSK users simultaneously
within a single time slot.
Subchannels
The standard specifies the downlink signal using Adaptive QPSK (AQPSK) modulation
(see 3GPP TS 45.004), where two "subchannel" binary sequences are multiplexed to
form a single QPSK sequence. The ratio of powers for the subchannels is referred to
as the "Subchannel Power Imbalance Ratio" (SCPIR). One of the subchannels is interpreted as interference. The value of SCPIR affects the shape of the AQPSK constellation. For an SCPIR of 0dB the constellation is square (as in "normal" QSPK), while for
other values of the SCPIR the constellation becomes rectangular.
Training sequences (TSCs)
A new set of training sequences (TSCs) has also been proposed (see 3GPP TS
45.002) for GMSK signals. The previous TSCs for GMSK bursts are listed as "Set 1",
while the new TSCs are listed as "Set 2". AQPSK signals can be formed using TSCs
from Set 1 on the first subchannel and TSCs from either Set 1 or Set 2 on the second
subchannel. In case a TSC from Set 2 is used, it should match the TSC from Set 1, i.e.
TSC<n> from Set 1 on subchannel 1 should match TSC<n> from Set 2 on subchannel
2, for n = 0..7.
TSC vs "Midamble"
The terms TSC and Midamble are used synonymously in the standard. In this documentation, we use the term TSC to refer to the known symbol sequence in the middle
of the slot.
The R&S FSW GSM application supports measurement of the following signals:
●
GMSK bursts using the TSCs from Set 1 or Set 2
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●
AQPSK bursts with combinations of TSCs from Set 1 and 2 on the subchannels
●
AQPSK bursts with a user-specified SCPIR
Basics on GSM measurements
The following measurements of the above signals are supported:
●
Power vs Time
●
Demod (Constellation, EVM vs time, Phase error vs time, magnitude error vs time,
modulation accuracy)
●
Spectrum (modulation, transient) including limit check
●
Automatic trigger offset detection
Restriction for auto frame configuration
Auto Frame configuration only detects AQPSK normal bursts where the subchannels
have a TSC according to Table 5-3. The SCPIR value is detected with a resolution of
1 dB. To obtain reliable measurement results on AQPSK normal bursts, compare the
auto-detected slot settings with the settings of your device under test.
Table 5-3: Required subchannel - TSC assignment for AQPSK auto frame configuration
AQPSK modulation
AQPSK Subchannel 2
TSC j (Set 2)
0 1 2 3 4 5 6 7
x
x
x
Sub
cha
nnel
1
TSC
i
(Set
1)
TSC j (Set 1)
0 1 2 3 4 5 6 7
0
1
2 x x
3 x x
4
5
6
7 x x
x x
x x
x
x
x
x x
x
x
x
5.4 AQPSK modulation
The AQPSK modulation scheme as proposed for use in GSM systems is illustrated in
Figure 5-3. First, the bits from two users (subchannels 1 and 2) are interleaved. The
combined bit sequence is then mapped to an AQPSK constellation which depends on
the SCPIR value. The AQPSK symbols are then modulated using the linearized GMSK
pulse (see 3GPP TS 45.004).
x
x
x
x
x
x
x
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Basics on GSM measurements
I/Q data import and export
Figure 5-3: AQPSK modulation scheme for GSM systems
The proposed AQPSK mapping (as assumed in the R&S FSW GSM application) is
given in Table 5-4 and illustrated in Figure 5-4, where the first (leftmost) bit corre-
sponds to subchannel 1 and the second (rightmost) bit corresponds to subchannel 2.
Table 5-4: AQPSK symbol mappings [reproduced from 3GPP TS 45.004]
Modulating bits for
ai, b
i
(0,0)
(0,1)
(1,0)
(1,1)
AQPSK symbol in polar notation
s
i
jα
e
-jα
e
-jα
-e
jα
-e
The AQPSK modulation constellation diagram is shown in Figure 5-4, where the value
α is an angle related to the SCPIR as follows:
SCPIRdB = 20*log10[tan(α) ] dB
Figure 5-4: AQPSK constellation [reproduced from 3GPP TS 45.004].
5.5 I/Q data import and export
Baseband signals mostly occur as so-called complex baseband signals, i.e. a signal
representation that consists of two channels; the inphase (I) and the quadrature (Q)
channel. Such signals are referred to as I/Q signals. The complete modulation information and even distortion that originates from the RF, IF or baseband domains can be
analyzed in the I/Q baseband.
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Basics on GSM measurements
Trigger settings
Importing and exporting I/Q signals is useful for various applications:
●
Generating and saving I/Q signals in an RF or baseband signal generator or in
external software tools to analyze them with the R&S FSW later.
●
Capturing and saving I/Q signals with the R&S FSW to analyze them with the
R&S FSW or an external software tool later
As opposed to storing trace data, which can be averaged or restricted to peak values, I/Q data is stored as it was captured, without further processing. Multi-channel
data is not supported.
The data is stored as complex values in 32-bit floating-point format. The I/Q data is
stored in a format with the file extension .iq.tar.
For a detailed description, see the R&S FSW I/Q Analyzer and I/Q Input User Manual.
For example, you can capture I/Q data using the I/Q Analyzer application, if available,
and then analyze that data later using the R&S FSW GSM application.
An application note on converting Rohde & Schwarz I/Q data files is available from the
Rohde & Schwarz website:
1EF85: Converting R&S I/Q data files
I/Q data import and export is only available for "Modulation Accuracy" measurements.
(MCWN measurements include a combination of I/Q-based and sweep-based measurements.)
Export only in MSRA mode
In MSRA mode, I/Q data can only be exported to other applications; I/Q data cannot be
imported to the MSRA primary or any MSRA secondary applications.
5.6 Trigger settings
The GSM measurements can be performed in "Free Run" (untriggered) mode; however, an external trigger or a power trigger can speed up measurements. To perform
measurements the R&S FSW GSM application needs the frame start as a time reference. The R&S FSW GSM application searches for a frame start after every I/Q data
acquisition. The required search effort depends on the trigger mode.
Consider the following trigger mode settings:
●
In "Free Run" mode, i.e. without any trigger, the R&S FSW GSM application totally
relies on the frame/slot configuration to find the frame start. The start of a measurement is not triggered. Once a measurement is completed, another is started immediately. For an unambiguous frame configuration, the GSM application searches for
the frame start inside the captured I/Q data. This is the slowest frame search
mode.
●
With a "Power Trigger", the measurement is triggered by the power ramp of the
received GSM bursts. Nevertheless the R&S FSW GSM application still relies on
the frame/slot configuration to find the frame start inside the captured I/Q data.
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Defining the scope of the measurement
Once a measurement is completed, the R&S FSW GSM application waits for the
next trigger event to start the next measurement. The search for the frame start is
as in "Free Run" mode, except that the I/Q data capture is triggered.
●
With the "External Trigger", the measurement is triggered by an external signal
(connected to the "EXT TRIGGER" input of the R&S FSW). The R&S FSW GSM
application assumes that the frame start (i.e. the "active part" in slot 0) directly follows the trigger event. An external trigger requires a correct setting of the trigger
offset. The search is faster compared to the free run and power trigger modes. Use
an external trigger to maximize the measurement speed or if the frame configuration is ambiguous (i.e. if the slot properties are cyclic with a cycle less than the
frame duration).
Trigger source for MSRA primary
Any trigger source other than "Free Run" defined for the MSRA primary is ignored
when determining the frame start in the R&S FSW GSM application. For this purpose,
the trigger is considered to be in "Free Run" mode.
Refer to Chapter 6.3.4, "Trigger settings", on page 113 to learn more about appropriate
trigger settings and to Chapter 6.3.2, "Signal description", on page 90 for information
on the frame/slot configuration.
Refer to "Automatic Trigger Offset" on page 131 to learn more about setting the trigger
offset automatically.
5.7 Defining the scope of the measurement
The R&S FSW GSM application is slot-based. It can measure up to 8 consecutive
GSM slots (1 frame) and store the power results for all slots ("Power vs Time" and
"Power vs Slot" measurements, see "PvT Full Burst" on page 28 and "Power vs Slot"
on page 27).
In previous Rohde & Schwarz signal and spectrum analyzers, the term "burst" was
used synonymously for "slot". In this documentation, we use the term "burst" when the
signal behaves like a pulse, i.e. power is ramped up and down. The up ramp is referred
to as the rising edge, the down ramp as the falling edge. A burst may occur within one
or more slots, which is a measure of time in the captured signal. Thus, a burst may
coincide with a slot, but it must not necessarily do so.
Usually only slots in which a burst is expected are of interest. Such slots are defined as
active slots in the signal description.
Within this slot scope (defined by First Slot to measure and Number of Slots to mea-
sure), a single slot ( Slot to Measure) is selected for a more detailed analysis (e.g.
"Modulation Accuracy" measurement, see "Modulation Accuracy" on page 21). The
Slot to Measure is required for the following reasons:
●
To provide the reference power and time reference for the "Power vs Time" measurement (see "PvT Full Burst" on page 28). Typically, the masks for all slots are
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Defining the scope of the measurement
time-aligned according to the timing of the Slot to Measure (see "Limit Line Time
Alignment" on page 127).
●
All "Modulation Spectrum" results are based on the Slot to Measure (see "Modula-
tion Spectrum Graph" on page 23). (The results of all "Transient Spectrum" dia-
grams are based on the slot scope, i.e. on the interval defined by the First Slot to
measure and the Number of Slots to measure, see "Transient Spectrum Graph"
on page 29).
●
All results that require demodulation of one slot and statistical analysis (e.g. Modu-
lation Accuracy, Phase Error, and EVM) are based on the Slot to Measure.
The slot scope is defined in the "Demodulation Settings" (see Chapter 6.3.6.1, "Slot
scope", on page 121), and it is indicated by a filled green box in the "Frame Configura-
tion" (see Figure 5-6). The Slot to Measure is indicated by a filled blue box.
Frame configuration and slot scope in the channel bar
In the channel bar of the R&S FSW GSM application, as well as in the configuration
"Overview", the current frame configuration and slot scope are visualized in a miniature
graphic. Furthermore, the burst type and modulation of the Slot to Measure are indicated.
Figure 5-5: Frame configuration in GSM application channel bar
The graphic can be interpreted as follows:
Shape/Color Meaning
Each slot is represented by a small box
Active slots are indicated by polygonal symbols
Slots within the defined slot scope are highlighted green
The defined Slot to Measure is highlighted blue; the burst type and modulation defined
for this slot are indicated to the right of the graphic
Frame configuration in the Frame and Slot Scope dialog boxes
The same graphic is displayed in the "Frame Configuration" of the "Frame" dialog box
(see "Frame Configuration: Select Slot to Configure" on page 93) and in the "Slot
Scope" tab of the "Demodulation" dialog box (see Chapter 6.3.6.1, "Slot scope",
on page 121).
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Overview of filters in the R&S FSW GSM application
Figure 5-6: Frame configuration in "Slot Scope" settings
This graphic can be interpreted as follows:
●
Each slot is represented by its number (0 to 7).
●
Slot numbers within the defined slot scope are highlighted green.
●
The number of the defined Slot to Measure is highlighted blue.
●
Active slots are indicated by polygonal symbols above the number which contain
the following information:
– The burst type, e.g. "Norm" for a normal burst
– The modulation, e.g. GMSK
– The training sequence TSC (and Set) or Sync (for access bursts)
5.8 Overview of filters in the R&S FSW GSM application
The R&S FSW GSM application requires a number of filters for different stages of signal processing. These include the "Multicarrier" filter (for multicarrier base station measurements only), the "Power vs Time" filter and the "Measurement" filter. A signal flow
diagram is shown in Figure 5-7 to illustrate where the different filters are used.
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Overview of filters in the R&S FSW GSM application
Figure 5-7: Signal flow diagram highlighting filtering operations
5.8.1 Power vs time filter
The "Power vs Time" filter is used to suppress out-of-band interference in the "Power
vs Time" measurement (see "PvT Full Burst" on page 28).
The following filters are available:
Single-carrier filters:
●
1 MHz Gauss
●
500 kHz Gauss
●
600 kHz
Multicarrier filters:
●
400 kHz MC
●
300 kHz MC
The magnitude and step responses of the different "Power vs Time" filters are shown in
Figure 5-8 and Figure 5-9, respectively. In general, the smaller the filter bandwidth, the
worse the step response becomes (in terms of "ringing" effects) and the better the suppression of interference at higher frequencies. Gaussian type filters are especially useful for signals with "sharp" edges as the step response does not exhibit overshoot.
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Overview of filters in the R&S FSW GSM application
Figure 5-8: Magnitude response of the Power vs Time filters
Figure 5-9: Step response of the Power vs Time filters
5.8.2 Multicarrier filter
The "Multicarrier" filter is a special filter that is applied to the captured I/Q data if the
device is defined as a multicarrier type (see "Device Type" on page 91). This filter is
used to suppress neighboring channels which may disturb measurement of the channel of interest. The output from the "Multicarrier" filter is used to perform synchronization and demodulation. The frequency response of the "Multicarrier" filter is shown in
Figure 5-10.
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5.8.3 Measurement filter
Basics on GSM measurements
Overview of filters in the R&S FSW GSM application
Figure 5-10: Frequency response of the Multicarrier filter
The "Measurement" filter is used to limit the bandwidth of the demodulation measurements and is described in the 3GPP standard document TS 45.005 for QPSK, 8PSK,
16QAM and 32QAM as follows:
●
a raised-cosine filter with roll-off 0.25 and single side-band 6 dB bandwidth 90 kHz
for normal symbol rate and for higher symbol-rate using narrow bandwidth pulseshaping filter
●
a raised-cosine filter with roll-off 0.25 and single side-band 6 dB bandwidth 108
kHz for higher symbol-rate using wide bandwidth pulse-shaping filter
In addition to these filters, a "Measurement" filter for GMSK is used in the R&S FSW
GSM application to limit the effects of out-of-band interference due to the high sample
rate of 6.5 MHz which is used. The magnitude responses of all the "Measurement" filters are shown in Figure 5-11.
Figure 5-11: Magnitude responses of Measurement filters for demodulation measurements
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5.9 Dependency of slot parameters
Basics on GSM measurements
Definition of the symbol period
The parameters that define a slot used for a GSM measurement are dependent on
each other, and only the following combinations of these parameters are available in
the R&S FSW GSM application (see Chapter 6.3.2.3, "Slot settings", on page 94).
Table 5-5: Dependency of slot parameters
Burst Type Modulation Filter TSC
AB GMSK GMSK Pulse TS 0, TS 1, TS 2
User
HSR QPSK, 16QAM, 32QAM Narrow Pulse,
Wide Pulse
NB 8PSK, 16QAM, 32QAM Linearized GMSK Pulse TSC 0, …, TSC 7
AQPSK Linearized GMSK Pulse Subchannel 1:
GMSK GMSK Pulse TSC 0 (Set 1), …, TSC 7 (Set 1),
5.10 Definition of the symbol period
TSC 0, …, TSC 7
User
User
TSC 0 (Set 1), …, TSC 7 (Set 1)
Subchannel 2:
TSC 0 (Set 1), …, TSC 7 (Set 1),
TSC 0 (Set 2), …, TSC 7 (Set 2)
Subchannel 1: User
Subchannel 2: User
TSC 0 (Set 2), …, TSC 7 (Set 2)
User
The following sections define the symbol period for various modulation types.
5.10.1 GMSK modulation (normal symbol rate)
The GMSK frequency pulse is defined in the standard document "3GPP TS 45.004" as
a Gaussian pulse convolved with a rectangular pulse, as illustrated at the top of Fig-
ure 5-12. The phase of a GMSK signal due to a sequence of symbols {α} is defined in
the standard as:
Equation 5-1: Phase of a GMSK signal due to a sequence of symbols
where:
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Definition of the symbol period
●
g(t): the frequency pulse
●
T: the normal symbol period
The modulating index is chosen such that the maximum phase change of π/2 radians
per data interval is achieved.
Note that the standard 3GPP TS 45.004 specifies in chapter "2.5 Output phase" for
Normal Burst GMSK:
"The time reference t' = 0 is the start of the active part of the burst as shown in figure 1.
This is also the start of the bit period of bit number 0 (the first tail bit) as defined in
3GPP TS 45.002."
The phase change due to the first tail symbol is illustrated at the bottom of Figure 5-12,
where you can see that the "decision instant" corresponding to the center of the frequency pulse occurs at the beginning of the first symbol period, i.e. at t' = 0."
Figure 5-12: GMSK frequency pulse (top) and phase of the first tail symbol (bottom)
5.10.2 8PSK, 16QAM, 32QAM, AQPSK modulation (normal symbol rate)
The EDGE transmit pulse is defined in the standard document "3GPP TS 45.004" as a
linearized GMSK pulse, as illustrated at the top of Figure 5-13. Note that according to
the definition in the standard, the center of the pulse occurs at 2.5 T, where T is the
normal symbol period (NSP). The baseband signal due to a sequence of symbols { }
is defined in the standard as:
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i
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0
Basics on GSM measurements
Definition of the symbol period
Equation 5-2: Baseband signal due to a sequence of symbols
where:
c0(t): the transmit pulse
Note that the standard 3GPP TS 45.004 specifies in chapter "3.5 Pulse shaping" for
normal burst 8PSK, 16QAM and 32QAM:
"The time reference t' = 0 is the start of the active part of the burst as shown in figure 3.
This is also the start of the symbol period of symbol number 0 (containing the first tail
bit) as defined in 3GPP TS 45.002."
For normal burst AQPSK, the standard 3GPP TS 45.004 specifies in chapter "6.5
Pulse shaping":
"The time reference t' = 0 is the start of the active part of the burst as shown in figure 6.
This is also the start of the symbol period of symbol number 0 (containing the first tail
bit) as defined in 3GPP TS 45.002."
The transmitted pulse for the first tail symbol is illustrated in the lower part of Fig-
ure 5-13, where it can be seen that the "decision instant" corresponding to the center
of the transmit pulse occurs in the center of the first symbol period, i.e. at t'=0.5T.
Figure 5-13: EDGE transmit pulse (top) and the first transmitted symbol (bottom)
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5.10.3 QPSK, 16QAM and 32QAM modulation (higher symbol rate)
Basics on GSM measurements
Definition of the symbol period
The description above also applies to the 16QAM and 32QAM modulations defined for
EDGE Evolution, using the "normal" symbol rate.
For the newer "reduced" symbol period (higher symbol rate) the standard document
"3GPP TS 45.004" defines two transmit pulse shapes; the so-called "narrow" and
"wide" pulses. The narrow pulse is the same linearized GMSK pulse as described in
Chapter 5.10.2, "8PSK, 16QAM, 32QAM, AQPSK modulation (normal symbol rate)",
on page 60, while the wide pulse was designed based on a numerically optimized set
of discrete filter coefficients. Both narrow and wide pulse shapes are illustrated at the
top of Figure 5-14, where you can see that the center of the pulse occurs at 3T, with T
being the reduced symbol period. For a sequence of symbols {
nal is defined in the standard as:
}, the transmitted sig-
Equation 5-3: The transmitted signal for a sequence of symbols
where:
c(t): the transmit pulse(which may be either the narrow or wide pulse)
Note that the standard 3GPP TS 45.004 specifies in chapter "5.5 Pulse shaping" for
higher symbol rate burst QPSK, 16QAM and 32QAM:
"The time reference t' = 0 is the start of the active part of the burst as shown in figure 3.
This is also the start of the symbol period of symbol number 0 (containing the first tail
bit) as defined in 3GPP TS 45.002."
The transmitted pulse for the first tail symbol is illustrated at the bottom of Figure 5-14,
where you can see that the "decision instant" corresponding to the center of the transmit pulse occurs in the center of the first symbol period, i.e. at t'=0.5T.
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Synchronization
Figure 5-14: EDGE Evolution transmit pulses (top) and the first transmitted symbols (bottom)
5.11 Synchronization
In order to detect and distinguish the individual slots and frames in the measured signal, the known signal sequence (Sync or TSC) must be found in each frame.
The synchronization process in the R&S FSW GSM application depends on how or if
the measurement is triggered.
Synchronization process for power trigger or free run mode
If a power trigger or no trigger is used (free run mode), the synchronization process
consists of the following steps:
1. Beginning at the start of a capture, the application searches for the synchronization
pattern (or TSC) of the Slot to Measure within one GSM frame length. This search
must be performed over the entire area, as the time of occurrence of the TSC
within the signal is not known. Thus, it is referred to as a "wide" search.
2. Once the synchronization point has been found, the application checks whether
enough samples remain in the capture buffer in order to analyze another frame. If
so, the process continues with the next step.
Otherwise, a new capture is started and the process begins with step 1 again.
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Synchronization
3. Assuming the signal is periodic, the synchronization point in the signal is moved by
exactly one GSM frame length. From there, a "narrow" search for the next TSC is
performed within only a small search area.
Thus, the remaining frames in the capture buffer can be synchronized quickly after
the initial "wide" search.
Steps 2 and 3 are repeated until all frames have been detected.
Figure 5-15: Synchronization using "wide" and "narrow" searches
Synchronization errors
The process described above assumes the GSM frame length in the signal is periodic
(within a given tolerance: "frame length error"). If this is not the case, however, for
example if a frame is too short, the application cannot synchronize to further frames
after the initial search.
Frequency hopping can lead to the same problem, as successive frames may not be
detected on the measured frequency channel.
Figure 5-16: Failed synchronization due to frame length error and resulting false search area
A special "Measure only on sync" option ensures that only those sections of the captured signal are processed further for which synchronization was possible, thus improving performance.
For frequency-hopping signals, it is recommended that you use a power trigger to
ensure capture starts with an active frame.
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5.12 Timeslot alignment
Basics on GSM measurements
Timeslot alignment
External trigger
When using an external trigger source, the application assumes that the trigger offset
is set such that the GSM frame start is aligned with the start of a capture. Therefore
only "narrow" searches are performed from the beginning of the Synchronization proc-
ess for power trigger or free run mode.
Reference Time
The definition of a "reference time" is necessary for the following description of timeslot
alignment. In the standard document "3GPP TS 45.010", in Section 5.7 it is stated that:
"Irrespective of the symbol duration used, the center of the training sequence shall
occur at the same point in time. "
This is illustrated in Figure 5.7.3 of the standard document "3GPP TS 45.010" which is
reproduced below for convenience (Figure 5-17). Due to this requirement, the "middle
of TSC" or "center of Active Part" shall be used as the reference time when specifying
timeslot alignment. Additionally, the "middle of TSC" is used for the alignment of the
Power vs Time limit masks (see also "Limit Line Time Alignment" on page 127).
Figure 5-17: Timing alignment between normal symbol period and reduced symbol period bursts
As described in Chapter 5.10, "Definition of the symbol period", on page 59, the middle
of TSC can be defined with respect to symbol periods and symbol decision instants.
This is illustrated in Figure 5-18. You can see that for normal symbol period bursts
(Normal bursts), the middle of TSC for GMSK occurs exactly at the decision instant of
symbol 74. However, for EDGE it occurs between the decision instants of symbols 73
and 74, while for reduced symbol period bursts (Higher Symbol Rate bursts), it occurs
exactly at the decision instant of symbol 88.
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Timeslot alignment
Figure 5-18: Middle of TSC for normal and reduced symbol period bursts.
Timeslot alignment within the frame
The standard document "3GPP TS 45.010" provides details on the alignment of slots
within the GSM frame:
"Optionally, the BTS may use a timeslot length of 157 normal symbol periods on timeslots with TN = 0 and 4, and 156 normal symbol periods on timeslots with TN = 1, 2, 3,
5, 6, 7, rather than 156.25 normal symbol periods on all timeslots"
The alignment of slots therefore falls under the "Not Equal Timeslot Length" (Equal
Timeslot Length = off) or the "Equal Timeslot Length" (Equal Timeslot Length = on) criterion (see also "Equal Timeslot Length" on page 93), which are illustrated in Fig-
ure 5-19.
Figure 5-19: "Not equal"(top) and "equal" (bottom) timeslot length criteria
Note that, since the reference point at the "middle of TSC" of each slot must coincide,
the length of the guard interval between successive bursts will depend on both the
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Delta to sync values
timeslot length and the symbol rate of bursts in successive slots. As stated in the standard "3GPP TS 45.010", for the "Equal Timeslot Length" case:
"… if there is a pair of different symbol period bursts on adjacent timeslots, then the
guard period between the two bursts shall be 8.5 normal symbol periods which equals
10.2 reduced symbol periods."
For the "Not Equal Timeslot Length" case, deriving the guard period length is somewhat more complicated, and the possible values are summarized in Table 5.7.2 of
"3GPP TS 45.010", reproduced below as Guard period lengths between different time-
slots, for convenience:
Table 5-6: Guard period lengths between different timeslots
Burst Transition Guard Period Between Timeslots (In
terms of normal symbol periods)
normal symbol
period to
normal symbol
period
normal symbol
period to
reduced symbol
period
reduced symbol
period to
normal symbol
period
reduced symbol
period to
reduced symbol
period
TS0 and TS1 or
TS4 and TS5
9 8 10.8 9.6
9.25 8.25 11.1 9.9
9.25 8.25 11.1 9.9
9.5 8.5 11.4 10.2
Any other timeslot pair
Guard Period Between Timeslots (In
terms of reduced symbol periods)
TS0 and TS1 or
TS4 and TS5
Any other timeslot
pair
5.13 Delta to sync values
The "Delta to Sync" value is defined as the distance between the mid of the TSC and
the TSC of the Slot to Measure.
The results are provided in the unit NSP, which stands for Normal Symbol Period, i.e.
the duration of one symbol using a normal symbol rate (approx. 3.69μs). The measured "Delta to Sync" values have a resolution of 0.02 NSP.
These values are either assumed to be constant (according to the 3GPP standard) or
measured, depending on the setting of the Limit Line Time Alignment parameter ("Slot
to measure" or "Per Slot").
According to the standard (see "Timeslot length" in 3GPP TS 45.010), there are either
eight slots of equal length (156.25 NSP), or slot 0 and slot 4 have a length of 157 NSP
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Limit checks
while all other slots have a length of 156 NSP. For details see Chapter 5.12, "Timeslot
alignment", on page 65.
The timeslot length is defined as the distance between the centers of the TSCs in successive slots. By setting the "Limit Time Alignment" parameter to "Per Slot", the "Delta
to Sync" values can be measured and used in order to verify the timeslot lengths.
Setting the Limit Line Time Alignment to "Slot to measure" displays the expected values (according to the standard and depending on the value of Equal Timeslot Length).
These values are summarized in Expected "Delta to Sync" values in normal symbol
periods (Slot to measure = 0, No. of slots = 8 and First slot to measure = 0).
Table 5-7: Expected "Delta to Sync" values in normal symbol periods
Slot
Number
Equal
Timeslot
Length =
On
Equal
Timeslot
Length =
Off
0 = Slot
to measure
0 156.25 312.50 468.75 625.00 781.25 937.50 1093.75
0 157 313 469 625 782 938 1094
1 2 3 4 5 6 7
5.14 Limit checks
● Limit check for modulation spectrum.......................................................................68
● Limit check for transient spectrum.......................................................................... 69
● Limit check for power vs time results...................................................................... 69
5.14.1 Limit check for modulation spectrum
The determined "Modulation Spectrum" values in the average (Avg) trace can be
checked against limits defined by the standard; the limit lines and the result of the limit
check are indicated in the "Modulation Spectrum" diagram (see "Modulation Spectrum
Graph" on page 23).
The GSM standards define both absolute and relative limits for the spectrum. The limit
check is considered to fail if both limits are exceeded.
The limits depend on the following parameters:
●
Frequency band
●
Device Type (only BTS type, not MS type)
●
Burst Type / Modulation / Filter - limits are different for Higher Symbol Rate and
Wide Pulse Filter (case 2) and others (case 1), see 3GPP TS 45.005, chapter
4.2.1.3
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5.14.2 Limit check for transient spectrum
Basics on GSM measurements
Limit checks
●
The measured reference power (30 kHz bandwidth)
●
The measured burst power (power level)
●
Number of active carriers for multicarrier BTS. The limit is relaxed by 10*log10(N)
dB for offset frequencies ≥1.8 MHz, see 3GPP TS 45.005 chapter 4.2.1.2
The determined "Transient Spectrum Accuracy" values can be checked against limits
defined by the standard; the limit lines and the result of the limit check are indicated in
the "Transient Spectrum" diagram (see "Transient Spectrum Graph" on page 29).
The limits depend on the following parameters:
●
Graph: Limit check of maximum (Max) trace
●
Table: Limit check of absolute and relative scalar values
●
The limit masks are generated adaptively from the measured signal.
●
The limits depend on the following parameters:
– Frequency band (not for MS)
– Burst Type / Modulation / Filter (not for MS)
– The measured reference (slot) power
5.14.3 Limit check for power vs time results
The determined "Power vs Time" values can be checked against limits defined by the
standard; the limit lines and the result of the limit check are indicated in the "Power vs
Time" diagram (see "PvT Full Burst" on page 28) and in the "Power vs Slot" table (see
"Power vs Slot" on page 27).
The limits depend on the following parameters:
●
The maximum (Max) trace is checked against the upper limit.
●
The minimum (Min) trace is checked against the lower limit.
●
The limit masks are generated adaptively from the measured signal according to
the following parameters:
– Frequency band (special masks for PCS1900 and DCS1800 BTS with GMSK)
– Burst type
– Modulation
– Filter
– The reference burst power is measured and the "0 dB line" of the limit mask is
assigned to it.
– For MS, the "-6 dB line" of the limit mask depends on the PCL. The PCL is
derived from the measured burst power.
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5.15 Impact of the "Statistic count"
Basics on GSM measurements
Impact of the "Statistic count"
Generally, the "Statistic Count" defines how many measurements (or: analysis steps)
are performed - equivalent to the "Sweep Count" in applications that perform sweeps.
In particular, the "Statistic Count" defines the number of frames to be included in statistical evaluations. For measurements on the Slot to Measure, the same slot is evaluated
in multiple frames, namely in the number specified by the "Statistic Count", for statistical evaluations.
For Trigger to Sync measurements, where only one result is calculated per data acquisition, the "Statistic Count" determines how many values are considered for averaging.
Statistic count for Trigger to Sync vs other measurements
As mentioned above, the "Statistic Count" for Trigger to Sync measurements refers to
the number of data acquisitions, whereas for all other measurements, the value refers
to the number of frames. Since usually more than one frame is captured per data
acquisition, the number of data acquisitions required to obtain the required number of
results (the "Statistic Count") may vary considerably. If both Trigger to Sync and other
result types are active at the same time, the latter are finished first and the traces (in
particular the current measurement trace) remains unchanged until the Trigger to Sync
measurement has also finished. The counter in the channel bar counts the "slower" of
the two events, i.e. the number of measurements if a Trigger to Sync result display is
active.
In MSRA mode, only a single data acquisition is performed (by the MSRA primary)
and the R&S FSW GSM application analyzes this data repeatedly. Thus, the Trigger to
Sync measurement will only count one data acquisition and can never reach a larger
"Statistic Count" value.
Tip: You can query the current value of the counter for both Trigger to Sync and other
measurements in remote control, as well. See [SENSe:]SWEep:COUNt:TRGS:
CURRent? on page 250.
Obviously, the "Statistic Count" has an impact on all results and values that are re-calculated after each measurement. The higher the count, the more values are taken into
consideration, and the more likely the result of the calculation will converge to a stable
value. On the other hand, the fewer measurements are considered, the higher the variance of the individual results, and the less reliable the calculation result will be.
For instance, if the "Statistic Count" is set to values smaller than 5, the measured reference power for "Modulation Spectrum Table" (see "Modulation Spectrum Table"
on page 24) and "Transient Spectrum Table" (see "Transient Spectrum Table"
on page 30) measurements increases. This leads to a higher variance of the measured
relative powers at the offset frequencies, and thus to a reduced measurement
dynamic.
For the Power vs Time (see "PvT Full Burst" on page 28) and "Power vs Slot" (see
"Power vs Slot" on page 27) measurements, a small "Statistic Count" increases the
variance of the measured slot powers. The slot power is required to calculate the PVT
limit lines.
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5.16 Multicarrier and wideband noise
Basics on GSM measurements
Multicarrier and wideband noise
For multicarrier measurements, the GSM standard defines limits for some parameters
concerning noise and intermodulation products. Thus, a new separate measurement is
provided by the R&S FSW GSM application: the Multicarrier Wideband Noise Mea-
surement (MCWN). This measurement comprises:
●
I/Q based measurements on the carriers to determine their power levels and reference powers
●
Frequency sweeps with RBWs of 100 kHz (to measure wideband noise) and
300 kHz (to measure intermodulation products)
●
Gated zero span measurements with an RBW of 30 kHz to measure narrowband
noise
● MCWN measurement process................................................................................71
● Contiguous vs non-contiguous multicarrier allocation.............................................73
● Manual reference power definition for MCWN measurements............................... 74
● Limit check for MCWN results.................................................................................75
● Intermodulation calculation..................................................................................... 77
● Wideband noise measurement............................................................................... 80
5.16.1 MCWN measurement process
The MCWN measurement consists of several sub-measurements, and may include
averaging processes.
Reference measurement
Optionally, a reference measurement is carried out to obtain suitable reference power
values for the actual noise measurement. The reference measurement can determine
the reference powers of the active carrier with the maximum power level, or optionally,
measure just one selected carrier. Several reference measurements can be performed
subsequently to calculate an average, thus ensuring stable reference values. Usually,
a small average count (10-12) is sufficient to obtain suitable results for the reference
measurement.
If this reference measurement is disabled, user-defined reference values are used for
relative results in the final measurement.
Narrowband noise measurement
If enabled, the narrowband noise is measured next. Narrowband noise measurement is
only available for multicarrier device types (see "Device Type" on page 91) for which
at least 2 carriers are configured (see Chapter 6.3.2.4, "Carrier settings", on page 97).
This measurement consists of zero span sweeps at a number of defined offset frequencies for each active carrier. That means I/Q data is captured at all relevant outermost carriers (i.e. 2 carriers for contiguous, 4 for non-contiguous carrier allocation),
one after another. From this I/Q data, all slots and timing information are determined.
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At each determined slot, a gated zero span measurement with an RBW and VBW of
30 kHz is performed, using the same I/Q data. Measurement time is from 50 to 90 % of
the useful part of the time slot excluding the mid amble. Measurement offsets are
400 kHz, 600 kHz and 1200 kHz, either below or above the outermost carrier.
If no slots are found, the results are invalid due to an invalid measurement setup, and a
warning is displayed in the status bar.
Several narrowband noise measurements can be performed subsequently to calculate
an average. Typically, a much larger average count than for the reference measurement is required to obtain suitable results for noise measurements, thus a separate
average count is available for reference and noise measurements.
Wideband noise and intermodulation sweeps
After the narrowband noise measurement, if either wideband noise or intermodulation,
or both, are enabled, frequency sweeps are performed in the defined span. Since the
standard requires different RBWs depending on the distance from the outermost carriers, several sweeps are required to obtain results for the complete span. The first
sweep measurement is performed using an RBW of 100 kHz. The second sweep measurement is performed using an RBW of 300 kHz.
For more details on how intermodulation is calculated see Chapter 5.16.5, "Intermodu-
lation calculation", on page 77.
For more details on how wideband noise results are determined, see Chapter 5.16.6,
"Wideband noise measurement", on page 80.
Evaluating the results for display
After all the reference and noise measurements have been performed, the measured
data is evaluated for the final result display. This includes the following procedures:
●
Averaging the results from several measurements
●
Putting the results in relation to the reference power values
●
Merging the traces according to the distance from the carriers and the position of
the intermodulation products
●
Performing limit checks (see Chapter 5.16.4, "Limit check for MCWN results",
on page 75)
(The details of evaluation are described for the individual evaluation methods in Chap-
ter 4.2.1, "Multicarrier evaluation methods", on page 34.)
Continuous measurement mode
If continuous sweep mode is selected, the measurement process described above is
repeated continuously, i.e. after the average count number of noise measurements, the
results are evaluated and displayed, a new reference sub-measurement is performed,
the noise measurements are repeated, and so on.
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5.16.2 Contiguous vs non-contiguous multicarrier allocation
Basics on GSM measurements
Multicarrier and wideband noise
In a standard GSM measurement scenario, multiple carriers are positioned with a fixed
spacing in one block. This setup is referred to as contiguous carrier allocation.
Carrier frequencies are allocated in a grid with a spacing of 200 kHz. The minimum
carrier spacing is 600 kHz.
Multi-standard radio (MSR) signals
Modern base stations may process multiple signals for different communication standards, for example two GSM subblocks with an LTE subblock in-between. In this case, if
you consider only the GSM carriers, the carriers are spaced regularly within the GSM
subblocks, but there is a gap between the two subblocks. Such a carrier setup is referred to as non-contiguous carrier allocation.
According to the 3GPP standard TS 51.021, a subblock is defined as "one contiguous
allocated block of spectrum for use by the same base station. There may be multiple
instances of subblocks within an RF bandwidth".
A gap is defined as "A frequency gap between two consecutive sub-blocks within an
RF bandwidth, where the RF requirements in the gap are based on co-existence for
uncoordinated operation."
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Level
RF bandwidth
gap between GSM subblocks
f
GSM
subblock
with 3
carriers
Figure 5-20: Non-contiguous carrier allocation
Non-contiguous carrier allocation
The R&S FSW GSM application now allows you to measure such non-contiguous carrier setups containing up to 16 carriers and a single gap (two subblocks). The position
of the individual carriers is defined as absolute frequency values. In addition, the position of the gap between the GSM subblocks is defined explicitly by the number of the
carrier after which it begins. The burst type and modulation can be defined individually
for each carrier to reflect different GSM configurations.
Limit checks for non-contiguous carrier allocation
In order to perform useful limit checks for such non-contiguous carrier allocation, the
limit lines are automatically adapted to the gap, so that other signals do not distort the
GSM limit check.
LTE
subblock
with 4
carriers
GSM
subblock
with 3
carriers
5.16.3 Manual reference power definition for MCWN measurements
For MCWN measurements, reference powers are required to calculate relative results
in the final measurement. These power levels can either be determined by a reference
measurement or they can be defined manually by the user. In the latter case, a power
level is defined, as well as three reference power levels for an RBW of 30 kHz,
100 kHz, and 300 kHz.
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The reference powers depend on the modulation characteristics. Some typical values
for various modulation types are provided in Table 5-8. The table indicates the refer-
ence powers for the three RBWs, relative to a defined power level. Since all reference
powers are measured with a smaller bandwidth than the power level, all values are
negative.
To define reference powers manually, define a power level and then subtract the values indicated in Reference powers relative to power level for various modulation types
for the used modulation to determine the reference power levels.
Table 5-8: Reference powers relative to power level for various modulation types
Modulation RBW = 300 kHz RBW = 100 kHz RBW = 30 kHz
NB GMSK -0.3 dB -2.2 dB -7.8 dB
NB 8PSK -1.7 dB -3.8 dB -7.7 dB
NB 16QAM -2.8 dB -4.5 dB -8.6 dB
NB 32QAM -2.9 dB -5.0 dB -9.3 dB
NB AQPSK (SCPIR = 0 dB) -2.5 dB -4.0 dB -8.5 dB
HSR-N QPSK -1.9 dB -3.9 dB -8.2 dB
HSR-N 16QAM -3.0 dB -4.7 dB -8.7 dB
HSR-N 32QAM -3.5 dB -5.5 dB -10.0 dB
HSR-W QPSK -1.6 dB -5.0 dB -10.0 dB
HSR-W 16QAM -3.1 dB -5.5 dB -10.3 dB
HSR-W 32QAM -3.1 dB -6.1 dB -11.3 dB
Example:
For a normal burst 8PSK signal, for example, and a power level of 35 dBm, the reference values according to Table 5-8 would be:
RBW Reference power
300 kHz 35 dBm - 1.7 dB = 33.3 dBm
100 kHz 35 dBm - 3.8 dB = 31.2 dBm
30 kHz 35 dBm - 7.7 dB = 27.3 dBm
5.16.4 Limit check for MCWN results
For MCWN measurements, various limit lines are calculated:
●
Wideband noise limits
●
Limits for intermodulation products that have to be measured with an RBW of
100 kHz
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●
Limits for intermodulation products that have to be measured with an RBW of
300 kHz
●
Limits for narrowband measurements that have to be measured with an RBW of
30 kHz. The limit is defined at 3 distinct measurement offsets each, then connected
by straight lines.
For each of these limit lines, a limit check is performed and the results can be queried.
They are also indicated in the "Spectrum Graph" on page 35."Spectrum Graph" display
(see
Exceptions
For measurements using an RBW of 100 kHz (wideband noise, certain intermodulation
products), the standard allows for the signal to exceed the specified limits in exceptional cases. Thus, you can define whether the limit check for MCWN measurements
considers these exceptions or not.
If exceptions are considered, the R&S FSW GSM application divides the measurement
range into 200 kHz bands. If the limit line in one of these bands is exceeded, a new,
higher limit line (with an exceptional level) is applied to the band. Only if this exceptional limit line is also exceeded, the limit check fails.
Maximum number of exceptions
The number of bands for which exceptional limits may be applied is restricted by the
standard (3GPP TS 45.005 (chapter 6.2.1.4.1) for single carrier, 3GPP 51.021 (chapter
6.12.3) for multicarrier BTS devices). Thus, the maximum number of bands that may
use exceptional limits is indicated for each measurement, as well as the number of
bands for which exceptions actually were used. The limit check compares the number
of employed exceptions with the number of maximum allowed exceptions.
Note that the maximum number of exceptional bands is based on the total number of
bands included in the following Exception ranges.
However, if the defined measurement span does not comprise all the bands in these
ranges, the maximum is not valid. In this case, the measurement may pass the limit
check although too many exceptions occurred for the restricted span.
To ensure the correct span is used, select "FREQ > Frequency Config > TX band" (see
"Setting the Span to Specific Values Automatically" on page 143).
Exception ranges
Exceptions are defined for two frequency ranges:
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Multicarrier and wideband noise
Figure 5-21: Exception ranges for multicarrier BTS limit checks
Range A
●
For multicarrier BTS device types:
Bands with an offset of 0 Hz to 2 MHz from the Tx band edges are counted. Bands
containing third order IM products and adjacent bands are ignored. For the exact
details see 3GPP TS 51.021, chapter 6.12.3.
●
For other device types
Bands in a distance of 600 kHz to 6 MHz above and below the outermost carrier
are counted. For the exact details see 3GPP TS 45.005, chapter 6.2.1.4.1.
The suffix required to query the number of exceptions in range A using remote commands (<k>) is 5.
Range B
●
For multicarrier BTS device types:
Bands inside the Tx band +/- 10 MHz are counted. Bands containing third order IM
products and adjacent bands are ignored. These are the (only) exceptions allowed
by the standard. Note that this range includes range A. The number of exceptions
thus includes the results from range A.
For the exact details see 3GPP TS 51.021, chapter 6.12.3.
●
For other device types
Bands in a distance over 6 MHz from the outermost carriers are counted. For the
exact details see 3GPP TS 45.005, chapter 6.2.1.4.1.
The suffix required to query the number of exceptions in range B using remote commands (<k>) is 6.
5.16.5 Intermodulation calculation
If intermodulation measurement is activated, the following calculations are performed.
If there are N active carriers with frequencies f1, f2, f3, ... fN, find all possible combinations of integer coefficients c1, c2, c3, ... cN for which the following equation is true:
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N
1k
Mc
k
N
1k
kIM
fc f
k
Basics on GSM measurements
Multicarrier and wideband noise
with M = intermodulation order
Use all those combinations of coefficients ck to calculate all possible intermodulation
frequencies of the given order M:
Example: Calculating intermodulation
For 3 carriers and IM order 3 these are all the theoretical combinations of ck:
Table 5-9: Intermodulation coefficients depending on number of carriers involved
1 carrier 2 carriers 3 carriers
0 0 3
0 3 0
3 0 0
0 0 -3
0 -3 0
-3 0 0
*) critical intermodulation
0 1 2
1 2 0
0 1 -2
1 -2 0
0 -1 2
-1 2 0
0 -1 -2
-1 -2 0
0 2 1
2 1 0
0 2 -1
2 -1 0 *)
0 -2 1
-2 1 0
0 -2 -1
-2 -1 0
1 0 2
1 0 -2
-1 0 2
-1 0 -2
2 0 1
-2 0 1
2 0 -1
-2 0 -1
1 1 1
1 1 -1
1 -1 1
-1 1 1
1 -1 -1
-1 -1 1
-1 -1 -1
Critical intermodulations
For critical intermodulations, the sum of all ck equals 1. For example 2*f1 – 1*f2, indicated in Table 5-9. They are critical because they are close to active carriers.
Note that for some combinations the following may apply:
●
Results are much too far away from the active carriers to be of relevance
●
Results are negative
●
Results have an identical IM frequency
Therefore the R&S FSW GSM application always checks the list of theoretical IM frequencies for the following aspects:
●
Intermodulation frequencies are ignored if they are outside the set frequency span
or the range defined by the standard (typically the Tx band +/- 2 MHz or 10 MHz).
●
For some measurements the GSM standard distinguishes how many carriers were
involved in generating the intermodulation. This means checking how many ck≠0.
Overlapping intermodulation limit lines
Intermodulations with different orders (for example 3 and 5) might fall on the exact
same frequency or so close that the corresponding limit line ranges overlap. In this
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case, the R&S FSW GSM application checks which IM’s limit value or relaxation value
applies according to the GSM standard.
The following cases may occur:
●
The overlapping limit lines have the same level.
LL A
LL B
f
IM
C
A
In this case, the point in the middle of both IM frequencies is determined and each
limit line is restricted to the area up to or starting from this point.
LL A
IM
B
LL B
f
IM
A
C
IM
B
●
The limit lines have different values and overlap over the entire span
LL A
LL B
f
IM
A
The less stringent limit line is applied.
IM
B
LL A
f
IM
A
●
The limit lines have different values and overlap over a partial span
IM
B
LL A
LL B
f
IM
C
D
A
The less stringent limit line is applied in the overlapping area; the distinct limit lines
are reduced to the remaining area(s).
IM
B
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5.16.6 Wideband noise measurement
Basics on GSM measurements
Multicarrier and wideband noise
LL A
LL B
f
IM
C
D
A
If wideband noise measurement is activated, the total frequency range of the measurement (defined by the selected span and the GSM band) is divided in non-overlapping
frequency segments according to the following rules:
●
Basically the segments are those defined in the tables in section 6.5.1. (and following) of the 3GPP TS 51.021 standard. The frequency offsets defined there are
applied relative to all outermost carriers, i.e. below the lowest carrier and above the
highest carrier. For non-contiguous mode the same principle is applied in the gap.
●
The resulting segments can be limited further by the defined span (see Chap-
ter 6.4.4.2, "Frequency settings", on page 141).
Note: If the span is too small, no wideband noise results can be calculated. For a
measurement according to standard, set the span to the TX band automatically
(see "Setting the Span to Specific Values Automatically" on page 143).
●
The segments are also limited by the maximum range demanded by the GSM standard ("…10 MHz outside the edge of the relevant transmit band…")
●
Adjacent segments are not merged to one large segment even if their limit values
happen to be identical.
●
The R&S FSW GSM application calculates where the standard demands intermodulation measurements instead of wideband noise measurement. It does not matter whether the intermodulation measurement is actually enabled or disabled in the
Noise measurement settings! All determined IM ranges override a wideband mea-
surement and replace it. This can make the wideband noise measurement segment start later, end earlier, or even vanish completely, or be separated in several
segments.
●
The middle of the gap is always a boundary (in case a wideband noise measurement segment exists there).
●
The gaps between 2 wideband noise limit line segments in the R&S FSW GSM
application are 1 Hz wide. These exact values can be output via remote commands. However, in the result display, some start and stop frequencies may appear
to be equal due to rounding effects.
IM
B
In the wideband noise tables, the results are then displayed for each segment (see
"Outer Wideband Table" on page 42).
Limit checks in wideband noise tables
For the wideband noise table results, which indicate the distance of the measured
value to the limit, limit exceptions do not cause the wideband noise segment to be split
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Automatic carrier detection
into two or more segments. The wideband noise table segments are constant and do
not vary from sweep to sweep depending on whether exceptions are set or not (as
opposed to the overall limits, see Chapter 5.16.4, "Limit check for MCWN results",
on page 75).
Figure 5-22: Wideband noise table: exceptions and delta to limit values
Example: Determining the "delta to limit" values for wideband noise tables
In Wideband noise table: exceptions and delta to limit values you see how the "delta to
limit" values are calculated. The measured wideband noise trace is blue. The limit line
(taking exceptions into account) is orange.
In each segment (StartX to StopX) the red arrow shows the worst delta to limit result.
●
The first segment fails, assuming no exception is allowed here.
●
The second segment passes.
●
In the third segment, the normal limit line (dotted line) fails at frequency "a". However, an exception is allowed and raises the limit for a certain range. Thus, the
R&S FSW GSM application recalculates the internal "delta to limit" trace (solid
orange line). The new worst result is determined at position "Worst3". This position
is then used to determine the noise power and limit line values for the wideband
noise table.
5.17 Automatic carrier detection
An automatic carrier detection function is now available (Adjusting the Center Fre-
quency Automatically (Auto Freq)). For multi-carrier measurements this function
detects the available carriers in the input signal within a frequency range of approximately 25 MHz to 2 GHz.
The "Auto Frequency" function is sensitive to overload conditions. Thus, before using
this function, make sure the reference level is not lower than the input signal's peak
power. On the other hand, avoid reference level settings that are much too high, as
they make very low carriers (approx. 50 dB under the reference level) disappear in the
noise floor and they will not be detected.
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5.18 GSM in MSRA operating mode
Basics on GSM measurements
GSM in MSRA operating mode
Optionally, use the Setting the Reference Level Automatically (Auto Level) function to
fine-tune the attenuators and the pre-amplifier AFTER the correct carrier frequencies
have been determined.
For MCWN measurements, make sure all detected carriers are in the measurement
span, for example using the "Carriers +/- 1.8 MHz" or "Carriers +/- 6 MHz" settings
(see "Setting the Span to Specific Values Automatically" on page 143).
The GSM application can also be used to analyze data in MSRA operating mode. In
MSRA operating mode, only the MSRA primary actually captures data; the MSRA
applications receive an extract of the captured data for analysis, referred to as the
application data. For the R&S FSW GSM application in MSRA operating mode, the
application data range is defined by the same settings used to define the signal capture in Signal and Spectrum Analyzer mode (see "Capture Time" on page 117). In
addition, a capture offset can be defined, i.e. an offset from the start of the captured
data to the start of the application data for GSM measurements. The "Magnitude Capture" display shows the application data of the R&S FSW GSM application in MSRA
mode.
MCWN measurements and MSRA mode
Only the default GSM I/Q measurement (Chapter 4.2, "Multicarrier wideband noise
measurements", on page 34)."Modulation Accuracy"...) is available in MSRA mode, not
the new MCWN measurement (see
Data coverage for each active application
Generally, if a signal contains multiple data channels for multiple standards, separate
applications are used to analyze each data channel. Thus, it is of interest to know
which application is analyzing which data channel. The MSRA primary display indicates the data covered by each application, restricted to the channel bandwidth used
by the corresponding standard (for GSM: 200 kHz), by vertical blue lines labeled with
the application name.
Analysis interval
However, the individual result displays of the application need not analyze the complete data range. The data range that is actually analyzed by the individual result display is referred to as the analysis interval.
In the R&S FSW GSM application the analysis interval is automatically determined
according to the basis of evaluation, for example the Slot to Measure or the slot scope.
The currently used analysis interval (in seconds, related to capture buffer start) is indicated in the window header for each result display.
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GSM in MSRA operating mode
Analysis line
A frequent question when analyzing multi-standard signals is how each data channel is
correlated (in time) to others. Thus, an analysis line has been introduced. The analysis
line is a common time marker for all MSRA secondary applications. It can be positioned in any MSRA secondary application or the MSRA primary and is then adjusted
in all other secondary applications. Thus, you can easily analyze the results at a specific time in the measurement in all secondary applications and determine correlations.
If the analysis interval of the secondary application contains the marked point in time,
the line is indicated in all time-based result displays, such as time, symbol, slot or bit
diagrams. By default, the analysis line is displayed. However, you can hide it from view
manually. In all result displays, the "AL" label in the window title bar indicates whether
the analysis line lies within the analysis interval or not:
●
orange "AL": the line lies within the interval
●
white "AL": the line lies within the interval, but is not displayed (hidden)
●
no "AL": the line lies outside the interval
Trigger source for MSRA primary
Any trigger source other than "Free Run" defined for the MSRA primary is ignored
when determining the frame start in the R&S FSW GSM application (see Chapter 5.6,
"Trigger settings", on page 52).
In the default state in MSRA operating mode, the Sequencer is active in continuous
mode. Thus, the MSRA primary performs a data acquisition and then the active applications evaluate the data in turn, after which the MSRA primary performs a data acquisition and so on. As opposed to some other R&S FSW applications in MSRA mode,
statistical evaluation of the traces (averaging, MinHold, MaxHold) is not reset after
each evaluation in the R&S FSW GSM application.
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GSM in MSRA operating mode
You can take advantage of this feature in the R&S FSW GSM application by performing continuous data acquisition in MSRA operating mode over a longer period (e.g.
over night), and then checking the average or MinHold/MaxHold trace to detect any
irregularities in the captured data.
For details on the MSRA operating mode see the R&S FSW MSRA User Manual.
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6 Configuration
Configuration
Multiple measurement channels and sequencer function
The default GSM I/Q measurement captures the I/Q data from the GSM signal and
determines various characteristic signal parameters such as the modulation accuracy,
transient spectrum, trigger to sync, etc. in just one measurement (see Chapter 4.1,
"GSM I/Q measurement results", on page 17).
For multicarrier wideband noise (MCWN) measurements, a different configuration is
required (see Chapter 6.4, "Multicarrier wideband noise (MCWN) measurements",
on page 132).
The settings required to configure each of these measurements are described here.
Selecting the measurement type
► To select a different measurement type, do one of the following:
● Select the "Overview" softkey. In the "Overview", select the "Select Measurement" button. Select the required measurement.
● Press the [MEAS] key. In the "Select Measurement" dialog box, select the
required measurement.
Remote command:
CONFigure:MEASurement on page 193
● Multiple measurement channels and sequencer function.......................................85
● Display configuration...............................................................................................87
● Modulation accuracy measurement configuration...................................................87
● Multicarrier wideband noise (MCWN) measurements...........................................132
6.1 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. These settings include the input
source, the type of data to be processed (I/Q or RF data), frequency and level settings,
measurement functions etc. If you want to perform the same measurement but with different center frequencies, for instance, or process the same input data with different
measurement functions, there are two ways to do so:
●
Change the settings in the measurement channel for each measurement scenario.
In this case the results of each measurement are updated each time you change
the settings and you cannot compare them or analyze them together without storing them on an external medium.
●
Activate a new measurement channel for the same application.
In the latter case, the two measurement scenarios with their different settings are
displayed simultaneously in separate tabs, and you can switch between the tabs to
compare the results.
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Configuration
Multiple measurement channels and sequencer function
For example, you can activate one GSM measurement channel to perform a GSM
modulation accuracy measurement for an unknown signal, and a second channel
to perform a multicarrier measurement using the same GSM input source. Then
you can monitor all results at the same time in the "MultiView" tab.
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 on the R&S FSW at any time. If one measurement is running and you start another, or switch to another channel, the first measurement is stopped. In order to perform the different measurements you configured in
multiple channels, you must switch from one tab to another.
However, you can enable a Sequencer function that automatically calls up each activated measurement channel in turn. This means the measurements configured in the
channels are performed one after the other in the order of the tabs. The currently
active measurement is indicated by a
the individual channels are updated in the corresponding tab (as well as the "MultiView") as the measurements are performed. Sequencer operation is independent of
the currently displayed tab; for example, you can analyze the SEM measurement while
the modulation accuracy measurement is being performed by the Sequencer.
symbol in the tab label. The result displays of
For details on the Sequencer function see the R&S FSW User Manual.
The Sequencer functions are only available in the "MultiView" tab.
Sequencer State........................................................................................................... 86
Sequencer Mode...........................................................................................................86
Sequencer State
Activates or deactivates the Sequencer. If activated, sequential operation according to
the selected Sequencer mode is started immediately.
Remote command:
SYSTem:SEQuencer on page 192
INITiate:SEQuencer:IMMediate on page 249
INITiate:SEQuencer:ABORt on page 248
Sequencer Mode
Defines how often which measurements are performed. The currently selected mode
softkey is highlighted blue. During an active Sequencer process, the selected mode
softkey is highlighted orange.
"Single Sequence"
Each measurement is performed once, until all measurements in all
active channels have been performed.
"Continuous Sequence"
The measurements in each active channel are performed one after
the other, repeatedly, in the same order, until sequential operation is
stopped.
This is the default Sequencer mode.
Remote command:
INITiate:SEQuencer:MODE on page 249
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6.2 Display configuration
Configuration
Modulation accuracy measurement configuration
The captured signal can be displayed using various evaluation methods. All evaluation
methods available for the selected measurement are displayed in the evaluation bar in
SmartGrid mode when you do one of the following:
●
Select the
●
Select the "Display Config" button in the "Overview".
●
Press the [MEAS] key.
●
Select the "Display Config" softkey in any GSM menu.
Up to 16 evaluation methods can be displayed simultaneously in separate windows.
The GSM evaluation methods are described in Chapter 4.1, "GSM I/Q measurement
results", on page 17 and Chapter 4.2.1, "Multicarrier evaluation methods", on page 34.
For details on working with the SmartGrid see the R&S FSW Getting Started manual.
"SmartGrid" icon from the toolbar.
6.3 Modulation accuracy measurement configuration
GSM measurements require a special application on the R&S FSW, which you activate
using the [MODE] key.
When you switch a measurement channel to the GSM application the first time, a set of
parameters is passed on from the currently active application. After initial setup, the
parameters for the measurement channel are stored upon exiting and restored upon
re-entering the channel. Thus, you can switch between applications quickly and easily.
When you activate a measurement channel in the GSM application, a GSM modulation
accuracy measurement for the input signal is started automatically with the default configuration. The "GSM" menu is displayed and provides access to the most important
configuration functions.
The [Marker Funct] and [Lines] menus are currently not used.
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Modulation accuracy measurement configuration
Importing and Exporting I/Q Data
The I/Q data to be evaluated in the GSM application ("Modulation Accuracy" measurement only) can not only be captured by the GSM application itself, it can also be imported to the application, provided it has the correct format. Furthermore, the evaluated
I/Q data from the GSM application can be exported for further analysis in external
applications.
The import and export functions are available in the "Save/Recall" menu which is displayed when you select the
For details on importing and exporting I/Q data see the R&S FSW I/Q Analyzer User
Manual.
● Configuration overview............................................................................................88
● Signal description....................................................................................................90
● Input, output and frontend settings..........................................................................99
● Trigger settings......................................................................................................113
● Data acquisition.....................................................................................................116
● Demodulation........................................................................................................120
● Measurement settings...........................................................................................126
● Adjusting settings automatically............................................................................130
"Save" or "Open" icon in the toolbar.
6.3.1 Configuration overview
Access: [Meas Config] > "Overview"
Throughout the measurement channel configuration, an overview of the most important
currently defined settings is provided in the "Overview".
Note that the configuration "Overview" depends on the selected measurement type.
Configuration for multicarrier measurements is described in Chapter 6.4, "Multicarrier
wideband noise (MCWN) measurements", on page 132.
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Configuration
Modulation accuracy measurement configuration
Figure 6-1: Configuration "Overview" for Modulation Accuracy measurement
In addition to the main measurement settings, the "Overview" provides quick access to
the main settings dialog boxes. The individual configuration steps are displayed in the
order of the data flow. Thus, you can easily configure an entire measurement channel
from input over processing to output and analysis by stepping through the dialog boxes
as indicated in the "Overview".
In particular, the "Overview" provides quick access to the following configuration dialog
boxes (listed in the recommended order of processing):
1. Signal Description
See Chapter 6.3.2, "Signal description", on page 90
2. Input and Frontend Settings
See Chapter 6.3.3, "Input, output and frontend settings", on page 99
3. Triggering
See Chapter 6.3.4, "Trigger settings", on page 113
4. Data Acquisition
See Chapter 6.3.5, "Data acquisition", on page 116
5. Demodulation Settings
See Chapter 6.3.6, "Demodulation", on page 120
6. Measurement Settings
See Chapter 6.3.7, "Measurement settings", on page 126
7. Result Configuration
See Chapter 7.1, "Result configuration", on page 161
8. Display Configuration
See Chapter 6.2, "Display configuration", on page 87
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Modulation accuracy measurement configuration
To configure settings
► Select any button to open the corresponding dialog box. The corresponding dialog
box is opened with the focus on the selected setting.
For step-by-step instructions on configuring GSM measurements, see Chapter 9, "How
to perform measurements in the GSM application", on page 171.
Preset Channel
Select the "Preset Channel" button in the lower left-hand corner of the "Overview" to
restore all measurement settings in the current channel to their default values.
Note: Do not confuse the "Preset Channel" button with the [Preset] key, which restores
the entire instrument to its default values and thus closes all channels on the
R&S FSW (except for the default channel)!
Remote command:
SYSTem:PRESet:CHANnel[:EXEC] on page 191
Select Measurement
Selects a measurement to be performed.
See Chapter 4, "Measurements and result displays", on page 17.
Specific Settings for
The channel can contain several windows for different results. Thus, the settings indicated in the "Overview" and configured in the dialog boxes vary depending on the
selected window.
Select an active window from the "Specific Settings for" selection list that is displayed
in the "Overview" and in all window-specific configuration dialog boxes.
The "Overview" and dialog boxes are updated to indicate the settings for the selected
window.
6.3.2 Signal description
Access: "Overview" > "Signal Description"
The signal description provides information on the expected input signal, which optimizes frame detection and measurement.
● Device under test settings.......................................................................................90
● Frame......................................................................................................................92
● Slot settings.............................................................................................................94
● Carrier settings........................................................................................................97
6.3.2.1 Device under test settings
Access: "Overview" > "Signal Description" > "Device"
The type of device to be tested provides additional information on the signal to be
expected.
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Modulation accuracy measurement configuration
Device Type.................................................................................................................. 91
Frequency Band............................................................................................................91
Power Class..................................................................................................................92
Maximum Output Power per Carrier (multicarrier measurements only)........................92
Device Type
Defines the type of device under test (DUT). The following types are available:
●
BTS Normal
●
BTS Micro
●
BTS Pico
●
MS Normal
●
MS Small
●
Multicarrier BTS Wide Area
●
Multicarrier BTS Medium Range
●
Multicarrier BTS Local Area
The default device type is "BTS Normal".
Remote command:
CONFigure[:MS]:DEVice:TYPE on page 194
Frequency Band
The frequency band defines the frequency range used to transmit the signal.
For details see "Frequency bands and channels" on page 46.
The following frequency bands are supported:
●
DCS 1800
●
E-GSM 900
●
GSM 450
●
GSM 480
●
GSM 710
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Modulation accuracy measurement configuration
●
GSM 750
●
GSM 850
●
PCS 1900
●
P-GSM 900
●
R-GSM 900
●
T-GSM 380
●
T-GSM 410
●
T-GSM 810
●
T-GSM 900
The default frequency band is "E-GSM 900".
Remote command:
CONFigure[:MS]:NETWork[:TYPE] on page 196
CONFigure[:MS]:NETWork:FREQuency:BAND on page 195
Power Class
The following power classes are supported:
(For MCWN measurements no power class is used: "NONE".)
●
1, …, 8 (BTS)
●
1, …,5 (MS: GMSK)
●
E1, E2, E3 (MS: all except GMSK)
●
M1, M2, M3 (Micro BTS)
●
P1 (Pico BTS)
The default power class is 2.
Remote command:
CONFigure[:MS]:POWer:CLASs on page 196
Configuration
Maximum Output Power per Carrier (multicarrier measurements only)
Defines the maximum output power per carrier, which determines the limit lines for the
modulation spectrum (I/Q measurements) and MCWN measurement.
In "Auto" mode, the maximum measured power level for the carriers is used.
This setting is only available for multicarrier measurements.
Remote command:
CONFigure[:MS]:POWer:PCARrier:AUTO on page 198
CONFigure[:MS]:POWer:PCARrier on page 197
6.3.2.2 Frame
Access: "Overview" > "Signal Description" > "Frames"
Frame settings determine the frame configuration used by the device under test.
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Modulation accuracy measurement configuration
Equal Timeslot Length
This parameter is only taken into account if "Limit Time Alignment" is set to "Slot to
measure" (see "Limit Line Time Alignment" on page 127).
If activated, all slots of a frame are considered to have the same length (8 x 156.26
normal symbol periods).
In this case, the limit line for each slot (required for the "Power vs Time" spectrum
masks) is aligned by measuring the TSC of the Slot to Measure only, and using this
value to align the limit line for all slots in the frame (see also "PvT Full Burst"
on page 28).
If deactivated, slots number 0 and 4 of a frame have a longer duration, all others have
a shorter duration compared to the "Equal Timeslot Length" (157, 156, 156, 156, 157,
156, 156, 156 normal symbol periods).
See GPP TS 51.021 and 3GPP TS 45.010 chapter "6.7 Timeslot length" for further
details.
Remote command:
CONFigure[:MS]:CHANnel:FRAMe:EQUal on page 198
Frame Configuration: Select Slot to Configure
This area shows a graphical representation of the configuration of each slot. Select a
slot to display its "Slot" dialog box (see Chapter 6.3.2.3, "Slot settings", on page 94).
For active slots the following information is shown:
●
The burst type, e.g. "Normal (NB)" for a normal burst.
●
The modulation, e.g. GMSK.
●
The training sequence TSC (and Set)
For details on how to interpret the graphic, see "Frame configuration and slot scope in
the channel bar" on page 54.
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6.3.2.3 Slot settings
Configuration
Modulation accuracy measurement configuration
Access: "Overview" > "Signal Description" > "Slot"> "Slot1"/.../"Slot7"
The individual slots are configured on separate tabs. The dialog box for the selected
slot is displayed directly when you select a slot in the "Frame Configuration" graphic on
the "Frame" tab (see "Frame Configuration: Select Slot to Configure" on page 93).
Slot structure display
The basic slot structure according to the selected Frequency Band and Power Class is
displayed graphically for reference.
White fields indicate unknown data; colored fields indicate known symbol sequences.
The slot settings vary slightly for different burst types.
Figure 6-2: Slot configuration for normal and higher symbol rate bursts
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Modulation accuracy measurement configuration
Figure 6-3: Slot configuration for access burst
The "Slot" settings are dependant on each other, and only specific combinations of
these parameters are available in this dialog box (see Chapter 5.9, "Dependency of
slot parameters", on page 59).
Slot State (On/Off)
Activates or deactivates the selected slot. The R&S FSW GSM application expects an
input signal within the active slots only.
At least the Slot to Measure must be active in order to evaluate it.
Remote command:
CONFigure[:MS]:CHANnel:SLOT<Number>[:STATe] on page 199
Burst Type
Assigns a burst type to the selected slot.
The following burst types are supported:
●
Normal (NB)
●
Higher Symbol Rate (HB)
●
Access (AB)
The graphical slot structure is adapted according to the selected burst type.
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Modulation accuracy measurement configuration
Note: The "Slot" settings are dependant on each other, and only specific combinations
of these parameters are available in this dialog box (see Chapter 5.9, "Dependency of
slot parameters", on page 59).
Remote command:
CONFigure[:MS]:CHANnel:SLOT<Number>:TYPE on page 205
Modulation
Defines the modulation used in the slot.
The possible modulations depend on the set burst type (see Chapter 5.9, "Dependency
of slot parameters", on page 59).
The graphical slot structure is adapted according to the selected modulation.
Remote command:
CONFigure[:MS]:CHANnel:SLOT<Number>:MTYPe on page 200
SCPIR
This parameter is only available for AQPSK modulation.
It specifies the Subchannel Power Imbalance Ratio (SCPIR). The value of SCPIR
affects the shape of the AQPSK constellation (see Chapter 5.4, "AQPSK modulation",
on page 50). For an SCPIR of 0 dB the constellation is square (as in "normal" QPSK),
while for other values of SCPIR the constellation becomes rectangular.
Remote command:
CONFigure[:MS]:CHANnel:SLOT<s>:SCPir on page 200
Filter
Specifies the pulse shape of the modulator on the DUT and thus the measurement filter in the R&S FSW GSM application.
(For details see Chapter 5.8.3, "Measurement filter", on page 58).
The following filter types are supported for normal and higher symbol rate bursts:
●
GMSK Pulse
●
Linearized GMSK Pulse
●
Narrow Pulse
●
Wide Pulse
For access bursts, only a GMSK Pulse filter is supported.
Remote command:
CONFigure[:MS]:CHANnel:SLOT<Number>:FILTer on page 199
Timing Advance (Access Burst only)
Specifies the position of an access burst within a single slot as an offset in symbols
from the slot start.
Remote command:
CONFigure[:MS]:CHANnel:SLOT<Number>:TADVance on page 202
Training Sequence TSC[/]Sync
(Note: for Access bursts, this setting is labeled "Sync", but the functionality is the
same.)
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Modulation accuracy measurement configuration
The "Training Sequence TSC" or "Sync" values are known symbol sequences used to
synchronize the measured signal with the expected input signal in a single slot.
The available values depend on the modulation as indicated in the table below.
For user-defined TSCs, select "User" and define the training sequence in the User
TSC[/]User Sync table.
For more information on TSCs see "Training sequences (TSCs)" on page 49.
Remote command:
CONFigure[:MS]:CHANnel:SLOT<s>:TSC on page 203
AQPSK:
CONFigure[:MS]:CHANnel:SLOT<s>:SUBChannel<ch>:TSC on page 201
User TSC[/]User Sync
(Note: for Access bursts, this setting is labeled "User Sync", but the functionality is the
same.)
Defines the bits of the user-defined TSC or Sync. The number of bits depend on the
burst type and the modulation and is indicated in Table 6-1.
For AQPSK modulation, the training sequence is defined for each subchannel, see
Chapter 5.4, "AQPSK modulation", on page 50.
Note:
As the "User TSC" table in the dialog box only displays 25 bits at a time, a scrollbar
beneath the table allows you to display the remaining bits. The currently selected bit
number is indicated in the center of the scrollbar.
Table 6-1: Number of TSC bits depending on burst type and modulation
Burst Type Modulation Number of Bits
Normal GMSK 26
Normal 8PSK 78
Normal 16QAM 104
Normal 32QAM 130
Higher Symbol Rate QPSK 62
Higher Symbol Rate 16QAM 124
Higher Symbol Rate 32QAM 155
Access GMSK 41
Remote command:
CONFigure[:MS]:CHANnel:SLOT<s>:TSC:USER on page 204
AQPSK:
CONFigure[:MS]:CHANnel:SLOT<s>:SUBChannel<ch>:TSC:USER on page 201
6.3.2.4 Carrier settings
Access: "Overview" > "Signal Description" > "Carriers"
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Modulation accuracy measurement configuration
The "Carrier" settings define whether the expected signal contains a single or multiple
carriers. Multiple carriers can only be defined if a multicarrier Device Type is selected
(see Chapter 6.3.2.1, "Device under test settings", on page 90.
Up to 16 carriers can be configured for a single MCWN measurement.
The carriers can also be configured automatically, see
quency Automatically (Auto Freq)" on page 131.
Carrier Allocation...........................................................................................................99
Gap start after carrier (Non-contiguous carriers only)...................................................99
Active carriers............................................................................................................... 99
Frequency..................................................................................................................... 99
Modulation.....................................................................................................................99
"Adjusting the Center Fre-
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Modulation accuracy measurement configuration
Carrier Allocation
Defines whether a multicarrier measurement setup contains one subblock of regularly
spaced carriers only (contiguous), or two subblocks of carriers with a gap in-between
(non-contiguous).
For details see Chapter 5.16.2, "Contiguous vs non-contiguous multicarrier allocation",
on page 73.
Remote command:
CONFigure[:MS]:MCARrier:FALLocation[:MODE] on page 207
Gap start after carrier (Non-contiguous carriers only)
For non-contiguous setups (see Carrier Allocation) the position of the gap must be
defined as the number of the active carrier after which the gap starts.
Remote command:
CONFigure[:MS]:MCARrier:FALLocation:NCONtiguous:GSACarrier
on page 207
Active carriers
Defines which of the defined carriers are active for the current measurement.
Remote command:
CONFigure[:MS]:MCARrier:CARRier<c>[:STATe]? on page 205
Frequency
Defines the absolute frequency of each (active) carrier.
Remote command:
CONFigure[:MS]:MCARrier:CARRier<c>:FREQuency on page 206
Modulation
Defines the burst type, modulation and pulse shape filter of each (active) carrier.
For possible combinations see Chapter 5.9, "Dependency of slot parameters",
on page 59.
Note: This setting determines the appropriate limits from the 3GPP standard.
Remote command:
CONFigure[:MS]:MCARrier:CARRier<c>:MTYPe on page 206
6.3.3 Input, output and frontend settings
Access: "Overview" > "Input/Frontend"
The R&S FSW can evaluate signals from different input sources and provide various
types of output (such as noise or trigger signals).
● Input source settings.............................................................................................100
● Frequency settings................................................................................................105
● Amplitude settings.................................................................................................107
● Output settings...................................................................................................... 111
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6.3.3.1 Input source settings
Configuration
Modulation accuracy measurement configuration
Access: "Overview" > "Input/Frontend" > "Input Source"
The input source determines which data the R&S FSW analyzes.
The default input source for the R&S FSW is "Radio Frequency", i.e. the signal at the
"RF Input" connector of the R&S FSW. If no additional options are installed, this is the
only available input source.
Further input sources
The R&S FSW GSM application application can also process input from the following
optional sources:
●
I/Q Input files
●
"Digital Baseband" interface (R&S FSW-B17)
●
"Analog Baseband" interface (R&S FSW-B71)
●
Probes
For details, see the R&S FSW I/Q Analyzer and I/Q Input User Manual.
Since the Digital I/Q input and the Analog Baseband input use the same digital signal
path, both cannot be used simultaneously. When one is activated, established connections for the other are disconnected. When the second input is deactivated, connections to the first are re-established. Reconnecting can cause a short delay in data
transfer after switching the input source.
● Radio frequency input........................................................................................... 100
● Settings for input from I/Q data files......................................................................103
Radio frequency input
Access: "Overview" > "Input/Frontend" > "Input Source" > "Radio Frequency"
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