R&S SMBVB-K548 Bedienungsanleitung
R&S®SMBVB-K548
Crest Factor Reduction
User Manual
User Manual
Version 01
1179092202
(;Ý9F2)
This document describes the following software options:
●R&S®SMBVB-K548
1423.8820.02
This manual describes firmware version FW 4.70.006.xx and later of the R&S®SMBV100B.
© 2019 Rohde & Schwarz GmbH & Co. KG
Mühldorfstr. 15, 81671 München, Germany
Phone: +49 89 41 29 - 0
Fax: +49 89 41 29 12 164
Email: [email protected]
Internet: www.rohde-schwarz.com
Subject to change – Data without tolerance limits is not binding.
R&S® is a registered trademark of Rohde & Schwarz GmbH & Co. KG.
Trade names are trademarks of the owners.
1179.0922.02 | Version 01 | R&S®SMBVB-K548
Throughout this manual, products from Rohde & Schwarz are indicated without the ® symbol , e.g. R&S®SMBV100B is indicated as
R&S SMBVB. Linux® is abbreviated as Linux.
Contents
R&S®SMBVB-K548
3User Manual 1179.0922.02 ─ 01
Contents
1 Preface.................................................................................................... 5
1.1 About this Manual......................................................................................................... 5
1.2 Documentation Overview............................................................................................. 5
1.2.1 Getting Started Manual................................................................................................... 5
1.2.2 User Manuals and Help...................................................................................................6
1.2.3 Service Manual............................................................................................................... 6
1.2.4 Instrument Security Procedures......................................................................................6
1.2.5 Basic Safety Instructions.................................................................................................6
1.2.6 Data Sheets and Brochures............................................................................................ 6
1.2.7 Release Notes and Open Source Acknowledgment (OSA)............................................ 7
1.2.8 Application Notes, Application Cards, White Papers, etc................................................7
2 Welcome to the R&S SMBVB-K548 Option..........................................8
2.1 Accessing the Required Settings................................................................................ 8
2.2 Scope............................................................................................................................. 9
2.3 Notes on Screenshots.................................................................................................. 9
3 About the Crest Factor Reduction......................................................10
4 Crest Factor Reduction Settings........................................................ 11
5 Remote-Control Commands............................................................... 15
List of Commands................................................................................21
Index......................................................................................................22
Contents
R&S®SMBVB-K548
4User Manual 1179.0922.02 ─ 01
Preface
R&S®SMBVB-K548
5User Manual 1179.0922.02 ─ 01
1 Preface
1.1 About this Manual
This user manual provides all the information specific to the options R&S SMBVB-
K548. All general instrument functions and settings common to all applications and
operating modes are described in the main R&S SMBV100B user manual.
The main focus in this manual is on the provided settings and the tasks required to
generate a signal. The following topics are included:
●Welcome to the Crest Facor Reduction option R&S SMBVB-K548
Introduction to and getting familiar with the option
●About the Crest Facor Reduction
Background information on basic terms and principles in the context of the signal
generation
●Configuration and Settings
A concise description of all functions and settings available to configure signal gen-
eration with their corresponding remote control command
●Remote Control Commands
Remote commands required to configure and perform signal generation in a
remote environment, sorted by tasks
(Commands required to set up the instrument or to perform common tasks on the
instrument are provided in the R&S SMBV100B user manual)
Programming examples demonstrate the use of many commands and can usually
be executed directly for test purposes
●List of remote commands
Alphabetical list of all remote commands described in the manual
●Index
1.2 Documentation Overview
This section provides an overview of the R&S SMBV100B user documentation. Unless
specified otherwise, you find the documents on the R&S SMBV100B product page at:
www.rohde-schwarz.com/manual/smbv100b
1.2.1 Getting Started Manual
Introduces the R&S SMBV100B and describes how to set up and start working with the
product. Includes basic operations, typical measurement examples, and general infor-
mation, e.g. safety instructions, etc. A printed version is delivered with the instrument.
Documentation Overview
Preface
R&S®SMBVB-K548
6User Manual 1179.0922.02 ─ 01
1.2.2 User Manuals and Help
Separate manuals for the base unit and the software options are provided for down-
load:
●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 com-
mands with programming examples, and information on maintenance, instrument
interfaces and error messages. Includes the contents of the getting started manual.
●Software option manual
Contains the description of the specific functions of an option. Basic information on
operating the R&S SMBV100B is not included.
All user manuals are also available for download or for immediate display on the Inter-
net.
1.2.3 Service Manual
Describes the performance test for checking the rated specifications, module replace-
ment 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, https://gloris.rohde-schwarz.com).
1.2.4 Instrument Security Procedures
Deals with security issues when working with the R&S SMBV100B in secure areas. It
is available for download on the Internet.
1.2.5 Basic Safety Instructions
Contains safety instructions, operating conditions and further important information.
The printed document is delivered with the instrument.
1.2.6 Data Sheets and Brochures
The data sheet contains the technical specifications of the R&S SMBV100B. It also
lists the options and their order numbers and optional accessories.
The brochure provides an overview of the instrument and deals with the specific char-
acteristics.
See www.rohde-schwarz.com/brochure-datasheet/smbv100b
Documentation Overview
Preface
R&S®SMBVB-K548
7User Manual 1179.0922.02 ─ 01
1.2.7 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/smbv100b
1.2.8 Application Notes, Application Cards, White Papers, etc.
These documents deal with special applications or background information on particu-
lar topics.
See www.rohde-schwarz.com/application/smbv100b
Documentation Overview
Welcome to the R&S SMBVB-K548 Option
R&S®SMBVB-K548
8User Manual 1179.0922.02 ─ 01
2 Welcome to the R&S SMBVB-K548 Option
The R&S SMBVB-K548 is a software option that allows you to generate signals with
reduced crest factor.
R&S SMBVB-K548 key features
●Reduces the crest factor of a baseband signal through clipping the high signal
peaks and filtering the waveform afterwards.
●Can be applied to any waveform file loaded in the arbitrary waveform generator.
●It uses an iterative process to reach the desired crest factor delta.
●It is possible to adjust the filter characteristics. In simple mode, you can specify the
channel spacing and signal bandwidth. Alternatively in the advanced filter mode
you can specify the lowpass filter through passband and stopband frequencies.
This user manual contains a description of the functionality that the application pro-
vides, including remote control operation.
All functions not discussed in this manual are the same as in the base unit and are
described in the R&S SMBV100B user manual. The latest version is available at:
www.rohde-schwarz.com/manual/SMBV100B
Installation
You can find detailed installation instructions in the delivery of the option or in the
R&S SMBV100B service manual.
2.1 Accessing the Required Settings
1. In the block diagram of the R&S SMBV100B, select the "Baseband" > "ARB".
A dialog box opens that displays the provided general settings.
2. Select "Load Waveform".
Navigate to waveform file and load it.
3. Select "ARB > State > On".
4. Select "Crest Factor Reduction".
The signal generation is started. To apply the crest factor reduction with the default set-
tings, select "State > On".
Accessing the Required Settings
Welcome to the R&S SMBVB-K548 Option
R&S®SMBVB-K548
9User Manual 1179.0922.02 ─ 01
2.2 Scope
Tasks (in manual or remote operation) that are also performed in the base unit in the
same way are not described here.
In particular, it includes:
●Managing settings and data lists, like storing and loading settings, creating and
accessing data lists, or accessing files in a particular directory.
●Information on regular trigger, marker and clock signals and filter settings, if appro-
priate.
●General instrument configuration, such as checking the system configuration, con-
figuring networks and remote operation
●Using the common status registers
For a description of such tasks, see the R&S SMBV100B user manual.
2.3 Notes on Screenshots
When describing the functions of the product, we use sample screenshots. These
screenshots are meant to illustrate as many as possible of the provided functions and
possible interdependencies between parameters. The shown values may not represent
realistic usage scenarios.
The screenshots usually show a fully equipped product, that is: with all options instal-
led. Thus, some functions shown in the screenshots may not be available in your par-
ticular product configuration.
Notes on Screenshots
About the Crest Factor Reduction
R&S®SMBVB-K548
10User Manual 1179.0922.02 ─ 01
3 About the Crest Factor Reduction
Communication standards utilizing higher order modulation techniques or using multi-
ple carrier and complex signals consisting of the signals of more than one digital stan-
dard can feature a high crest factor. The signals of some digital standards can have
high crest factors also particularly with many channels and long sequences.
The crest factor represents the ratio of the peak voltage value to the RMS voltage
value, i.e. the peak to average ratio (PAR). The higher the crest factor and the resulting
dynamics of a signal, the greater the requirement for a power amplifier fed by the sig-
nal to be linear. A high crest factor arises for instance, when in a multi carrier signal the
carriers feature an identical start phase. This is based on the fact that the carriers are
periodically superposed that leads to high peak voltages in relation to the RMS voltage
values.
High crest factors entail two basic problems:
●The nonlinearity of the power amplifier (compression) causes intermodulation
which expands the spectrum (spectral regrowth).
●Since the level of the D/A converter is relative to the maximum value, the average
value is converted with a relatively low resolution. This leads to a high quantization
noise.
Both effects increase the adjacent-channel power.
Applying clipping and filtering
A common and simple approach for achieving a lower PAR is the combination of clip-
ping and filtering.
●Clipping is a technique that applies a wanted distortion to the signal.
The principle includes specifying a threshold, finding out the signal peaks once the
defined limits are exceeded and clipping them off. The level limit is specified as a
percentage of the highest peak value. Because clipping is done before filtering, the
procedure does not influence the spectrum. The error vector magnitude (EVM)
however increases.
However, signal clipping not only changes the peak value but also the average
value and the effect on the crest factor is unpredictable.
●After the clipping, filtering is applied. The used filters are specially designed so
that they filter out the distortion.
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