Rohde&Schwarz R&S®SMW200A Bit Error Rate Tester user manual User Manual
R&S®SMW-K80
Bit Error Rate Tester
User Manual
(;Üàì2)
1178829402
Version 06
This document describes the following software options:
●
R&S®SMW-K80 Bit Error Rate Tester (1414.6187.xx)
This manual describes firmware version FW 5.00.044.xx and later of the R&S®SMW200A.
© 2021 Rohde & Schwarz GmbH & Co. KG
Mühldorfstr. 15, 81671 München, 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.
1178.8294.02 | Version 06 | R&S®SMW-K80
The following abbreviations are used throughout this manual: R&S®SMW200A is abbreviated as R&S SMW; the license types
02/03/07/11/13/16/12 are abbreviated as xx.
R&S®SMW-K80
1 Welcome to the bit/block error rate tester option............................... 5
1.1 Accessing the bit/block error rate tester dialog.........................................................5
1.2 What's new.....................................................................................................................5
1.3 Documentation overview..............................................................................................6
1.3.1 Getting started manual....................................................................................................6
1.3.2 User manuals and help................................................................................................... 6
1.3.3 Tutorials...........................................................................................................................6
1.3.4 Service manual............................................................................................................... 6
1.3.5 Instrument security procedures.......................................................................................7
1.3.6 Printed safety instructions............................................................................................... 7
1.3.7 Data sheets and brochures............................................................................................. 7
Contents
Contents
1.3.8 Release notes and open source acknowledgment (OSA).............................................. 7
1.3.9 Application notes, application cards, white papers, etc...................................................7
1.4 Scope............................................................................................................................. 8
1.5 Notes on screenshots...................................................................................................8
2 About the bit/block error rate tester option.........................................9
2.1 Required options...........................................................................................................9
2.2 About bit and block error rate measurements........................................................... 9
2.2.1 PRBS data...................................................................................................................... 9
2.2.2 External restart..............................................................................................................10
2.2.3 Data enable................................................................................................................... 11
2.2.4 Pattern ignore................................................................................................................12
2.2.5 Terminating BER/BLER measurement..........................................................................12
2.3 BER/BLER test setup..................................................................................................13
2.4 BER/BLER self-test setup.......................................................................................... 14
3 Bit and block error rate settings.........................................................16
3.1 Common settings........................................................................................................16
3.2 Bit error rate settings..................................................................................................17
3.2.1 General settings............................................................................................................ 17
3.2.2 Data source...................................................................................................................21
3.2.3 Signal configuration settings......................................................................................... 22
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3.3 Block error rate settings.............................................................................................25
3.3.1 General settings............................................................................................................ 25
3.3.2 Data source...................................................................................................................29
3.3.3 Signal configuration settings......................................................................................... 30
4 Test generator settings........................................................................32
5 How to perform a self-test of the BER/BLER.....................................34
6 Remote-control commands.................................................................36
6.1 Programming examples............................................................................................. 36
6.2 BERT and BLER subsystems.................................................................................... 38
6.3 Test subsystem........................................................................................................... 47
Contents
List of commands................................................................................ 49
Index......................................................................................................50
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1 Welcome to the bit/block error rate tester
Welcome to the bit/block error rate tester option
What's new
option
The R&S SMW-K80 is a firmware application that adds a BER (Bit Error Rate) tester to
evaluate the bit error rate of a signal demodulated and decoded by a DUT. The
R&S SMW-K80 option also includes a BLER (Block Error Rate) measurement, used to
verify CRC checksums, where the ratio of erroneous blocks to total blocks yields the
block error rate.
The R&S SMW-K80 features:
●
Adjustable measurement for bit and block error measurements
●
Switching between test modes
●
Configurable connectors
This user manual contains a description of the functionality that the application provides, 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 SMW user manual. The latest version is available at:
www.rohde-schwarz.com/manual/SMW200A
Installation
You can find detailed installation instructions in the delivery of the option or in the
R&S SMW service manual.
1.1 Accessing the bit/block error rate tester dialog
To open the dialog with bit/block error rate tester settings
► In the block diagram of the R&S SMW, select "System Config > Setup > Bit/Block
Error Rate".
A dialog box opens that displays the provided general settings.
The signal generation is not started immediately. To start signal generation with the
default settings, select "State > On".
1.2 What's new
This manual describes firmware version FW 5.00.044.xx and later of the
R&S®SMW200A.
Compared to the previous version there are editorial changes only.
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1.3 Documentation overview
1.3.1 Getting started manual
1.3.2 User manuals and help
Welcome to the bit/block error rate tester option
Documentation overview
This section provides an overview of the R&S SMW user documentation. Unless specified otherwise, you find the documents on the R&S SMW product page at:
www.rohde-schwarz.com/manual/smw200a
Introduces the R&S SMW 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.
Separate manuals for the base unit and the software options are provided for download:
●
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.
●
Software option manual
Contains the description of the specific functions of an option. Basic information on
operating the R&S SMW is not included.
The contents of the user manuals are available as help in the R&S SMW. The help
offers quick, context-sensitive access to the complete information for the base unit and
the software options.
All user manuals are also available for download or for immediate display on the Internet.
1.3.3 Tutorials
The R&S SMW provides interactive examples and demonstrations on operating the
instrument in form of tutorials. A set of tutorials is available directly on the instrument.
1.3.4 Service manual
Describes the performance test for checking compliance with rated specifications, firmware update, troubleshooting, adjustments, installing options and maintenance.
The service manual is available for registered users on the global Rohde & Schwarz
information system (GLORIS):
https://gloris.rohde-schwarz.com
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1.3.5 Instrument security procedures
1.3.6 Printed safety instructions
1.3.7 Data sheets and brochures
Welcome to the bit/block error rate tester option
Documentation overview
Deals with security issues when working with the R&S SMW 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 SMW. 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 characteristics.
See www.rohde-schwarz.com/brochure-datasheet/smw200a
1.3.8 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/smw200a
1.3.9 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/smw200a and www.rohde-schwarz.com/
manual/smw200a
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1.4 Scope
Welcome to the bit/block error rate tester option
Notes on screenshots
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 saving 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 appropriate.
●
General instrument configuration, such as checking the system configuration, configuring networks and remote operation
●
Using the common status registers
For a description of such tasks, see the R&S SMW user manual.
1.5 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 installed. Thus, some functions shown in the screenshots may not be available in your particular product configuration.
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2 About the bit/block error rate tester option
2.1 Required options
2.2 About bit and block error rate measurements
About the bit/block error rate tester option
About bit and block error rate measurements
The equipment layout for bit and block error rate measurements includes:
●
Option standard or wideband baseband generator (R&S SMW-B10/-B9) per signal
path
●
Option baseband main module, one/two I/Q paths to RF (R&S SMW-B13/-B13T) or
Option wideband baseband main module two I/Q paths to RF (R&S SMW-B13XT)
●
Option bit/block error rate tester (R&S SMW-K80)
The BER (Bit Error Rate) tester evaluates the bit error rate of a signal. The DUT
decodes a known PRBS-modulated data sequence and returns clock and data signals
to the R&S SMW. The BER tester synchronizes to the PRBS sequence and counts the
bit errors. The bit error rate is defined by the ratio of the number of error bits to the total
number of bits.
The BLER calculates the checksum from the feedback data and compares it with the
checksum of the data signal that is fed to the DUT. If the two checksums differ, a block
error is counted. The quotient obtained by dividing the number of faulty blocks by the
total number of blocks is the block error rate.
2.2.1 PRBS data
The PRBS (Pseudo Random Binary Sequence) sequences are used for computing the
data. To detect faulty bits using the BER measurement, it is required to know the data
generation polynomial. Depending on the selected polynomial, these quasi-random bit
sequences are repeated periodically. A randomly selected initial status yields exactly
one subsequent status, therefore both occur only once in the whole sequence.
An advantage of the PRBS data is that the bit error detector must know only the polynomial but not the entire sequence. At measurement start, the feedback shift register is
filled once with the applied data sequence (which corresponds to the synchronization
time) and is then switched from "Fill" to "Feedback". This function creates a defined initial status and generates the same data that the applied data stream has. Faulty bits
can thus be identified and counted by comparing the received data with the results
obtained from the shift register.
Creating a defined initial status makes it possible to start the analysis anywhere in the
bitstream, i.e. the bitstream source and the analyzer need not be synchronized. Delays
of the DUT and transmission over long air paths, where the transmitter and the
receiver are located at separate sites, are therefore not a problem.
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About the bit/block error rate tester option
About bit and block error rate measurements
For details, see R&S SMW User Manual.
CRC polynomial
At the beginning of the data, the shift register is initialized with 0. All user data bits are
then shifted through the shift register. The checksum (CRC) component is then read
into a second register and compared bit by bit with the result of the calculation. The
supported CRC polynomial is as follows:
CCITT CRC 16 : G(x) = x16 + x12 + x5 + 1
The user data is marked by a signal that comes from the DUT and is fed to the "Data
Enable" input of the BERT interface, see Figure 2-5.
Clock signal
Usually the DUT provides the clock signal. If not, consider the following alternatives:
●
Use a custom digitally modulated signal and extract the bit clock from the clock output connector.
●
Generate a digitally modulated signal according to one of the supported digital
standards or play a waveform with the ARB and use one of the marker signals as
clock.
As the DUT causes a delay, we recommend that you measure the ratio of clock-to-data
transmission times with an oscilloscope. In the R&S SMW, observe the status indication for the clock and data lines, and for the synchronization in the "Bit/Block Error
Rate" dialog.
2.2.2 External restart
The "External Restart" function allows BER measurements with short signals or with
signals that are not continuously generated. Such signals usually do not contain any
whole-number multiples of PRBS sequences. An external signal input holds the measurement, integrates BER results of relevant (sub-) sequences and restarts the measurement when the data sequence begins.
Example:
Figure 2-1 illustrates the principle of external restart in case of short sequenced.
The length of the signal is too short for a complete PRBS sequence. The restart signal
restarts PRBS generation when the signal begins anew.
Figure 2-1: External restart
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About the bit/block error rate tester option
About bit and block error rate measurements
R&S SMW or the R&S WinIQSIM2 software generates frames, that contain PRBS data
continuously written to the user data fields. A restart is necessary, if the R&S SMW is
the data source and the total length of the signal does not contain a whole-number
multiple of a PRBS sequence.
Example:
The R&S SMW generates a TDMA signal with user data that contains the PRBS data
sequence; it writes the PRBS sequence continuously to the user data fields.
2.2.3 Data enable
Usually the data of bit error rate measurement signals contain more than PRBS data
(e.g. sync and preambles), which would result in bit errors. The "Data Enable" signal
interrupts the BER measurement for this data.
Example: Understanding the data enable signal for BER and BLER measurements
Figure 2-2: Data enable signal for BER measurement
Figure 2-2 shows an example of a TDMA signal with user data that contains the PRBS
data sequence, various check fields and the associated clock and data enable signals.
The data enable signal is low during the check fields so that these fields are ignored for
BER measurement.
In the case of the block error rate measurement, the "Data Enable" signal masks the
user data and thus not evaluate the user data.
Figure 2-3: Data enable signal with BLER measurement
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2.2.4 Pattern ignore
About the bit/block error rate tester option
About bit and block error rate measurements
When faulty frames (e.g. an incorrect checksum) are detected, some mobile radio
standards generate bit sequences of at least 32 bits with only "1" or "0" instead of
frame data. The "Pattern Ignore" function excludes those sequences from the measurement.
Example:
Lets assume that the DUT sets 50 bits to "0". These 50 bits plus the preceding "0" are
ignored in the bit error rate measurement.
Figure 2-4: Pattern ignore
2.2.5 Terminating BER/BLER measurement
The measurement results usually are in the range of 10-2 to 10-9 for the bit error rate,
and in the range of 10-2 to 10-4 for the block error rate. Hence, many bits or blocks must
be tested before a faulty bit or block occurs, which leads to longer measurement times.
Since 32-bit-wide counters are used for the total number of bits/blocks and the number
of error bits, the maximum measurement time is 4.29 x 109 bits.
To keep the measurement times short, consider the following:
●
Terminate the measurement manually.
●
Use one of the predefined termination criteria:
– Reaching a user-defined number of checked data bits/blocks.
– A maximum number of detected errors.
The measurement stops when at least one criteria is met. The display shows which of
the two criteria caused the measurement to stop.
The BER/BLER measures statistical bit/block errors, i.e. errors which occur at random.
A single measurement determines the exact number of errors in the measured interval,
but it is only statistically reliable when a sufficient number of errors occur in the measured interval. A sufficient number of errors makes sure that the single BER/BLER
measurement result approaches the true error rate with high probability.
Bit error rates of approximately 50 % indicate a faulty measurement.
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2.3 BER/BLER test setup
About the bit/block error rate tester option
BER/BLER test setup
In the case of continuously generated signals that contain whole-number multiples of
the PRBS sequence, the measurement occurs without interruption. The measurement
only uses the data and clock lines of the BERT interface. The length of the random
sequence is calculated as follows:
PRBS length = 2
power of the degree of the polynomial
- 1
For example, the length of the PRBS9 sequence is 511 = 29 - 1.
Figure 2-5 shows an example of the bit/block error rate measurement test setup.
BERT/BLER testing requires test signal (PRBS data sequence) that is fed to the DUT,
and a set of different control signals, like the clock, data and restart signals. You can
generate the test signal in the fowlloing ways:
●
Internally - with one of the digital standards or as custom digital modulated signal
●
Externally - for example with the R&S WinIQSIM2 software and play this signal with
the ARB.
The test signal is output at the RF A/RF B connector; the control signal at the USER x
connectors. The latter is connectors with definable signal. Assign the dedicated BERT/
BLER signals according to the current cabling.
Figure 2-5: Example of a test setup for bit or block error rate measurement
1 = R&S SMW front panel (part view)
2 = R&S SMW rear panel (part view)
DUT = Device under test
Test signal = PRBS data sequence (RF A/RF B connector), see Chapter 2.2.1, "PRBS data", on page 9
Restart = Input signal for BER measurements (USER 1 connector), see Chapter 2.2.2, "External
restart", on page 10.
Data = Input signal (USER 2 connector), see Chapter 2.2.1, "PRBS data", on page 9
Data enable = Input signal (USER 4 connector), see Chapter 2.2.3, "Data enable", on page 11
Clock = Input signal (USER 5 connector), see "Clock signal" on page 10
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2.4 BER/BLER self-test setup
About the bit/block error rate tester option
BER/BLER self-test setup
The BER/BLER self-test validates the BER and BLER measurements.
You can perform self-tests for different signals, which mainly differ in the routing of the
signals. You can assign the BER/BLER signals at the global USER x connectors.
These connectors serve as input or output interface and, depending on the selected
direction, also as an interface for different signals.
When you specify a connector for input signals, the R&S SMW routes the assigned
BER signal internally. For external tests, you can set one connector as output and a
second connector as input. Connect the connectors with a cable, define the direction
and assign the signals according to the particular test case.
As the R&S SMW has fewer connectors than BER signals, you can execute the selftest for more signals using these routing possibilities.
Despite the naming of the "BER", the signals apply to both, the BER and BLER measurements.
Self-test with output and input signals
To perform a self-test, assign at least one input / output signal pair and connect the
corresponding USER x connectors with a BNC cable. Table 2-1 shows the possible
loop back types.
You can configure 3 loops at most simultaneously, because every loop requires an
input and output signal.
Table 2-1: Possible loops and the required input and output signals
Loop back type Signal input Signal output
Data signal BER Data BER TestGen Data
Data enable signal BER Data Enable BER TestGen Data
Enable
Restart signal BER Restart BER TestGen Restart
Clock signal BER Clock BER TestGen Clock
Example: "BER Clock" and "BER Data" signal loops; "BER Data Enable" signal
routed internally
Figure 2-6 shows an example setup with a clock and data signal loop.
The signal to connector mapping in the "System Config > Setup > Bit/Block Error Rate
> Signal Configuration > Global Connectors" dialog is as follows:
●
"User 1 > Direction = Output" and "User 1 > Signal = BER TestGen Clock"
●
"User 2 > Direction = Input" and "User 2 > Signal = BER Clock"
●
"User 4 > Direction = Output" and "User 4 > Signal = BER TestGen Data"
●
"User 5 > Direction = Input" and "User 5 > Signal = BER Data"
●
"User 3 > Direction = Input" and "User 3 > Signal = BER Data Enable"
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About the bit/block error rate tester option
BER/BLER self-test setup
Figure 2-6: Looping back of the clock and data signals (the BER Data Enable signal is routed inter-
1 = R&S SMW front panel
2 = R&S SMW rear panel
nally)
Self-test with coherent signal direction
Select either all input or output signals for the self-test. The error rate tester tests the
outgoing signal. The R&S SMW routes the signal internally, cable connections are not
required.
Example:
The signal to connector mapping in the "System Config > Setup > Bit/Block Error Rate
> Signal Configuration > Global Connectors" dialog is as follows:
●
"User 1 > Direction = Input" and "User 1 > Signal = BER Data"
●
"User 2 > Direction = Input" and "User 2 > Signal = BER Clock"
●
"User 4 > Direction = Input" and "User 4 > Signal = BER Data Enable"
●
"User 5 > Direction = Input" and "User 5 > Signal = BER Restart"
●
"User 3 > Signal = Not Used"
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3 Bit and block error rate settings
Bit and block error rate settings
Common settings
Access:
► Select "System Config > Setup > Bit/Block Error Rate > General".
The "General" dialog contains file settings relevant for both test modes and allows
the start of the measurement.
● Common settings.................................................................................................... 16
● Bit error rate settings...............................................................................................17
● Block error rate settings.......................................................................................... 25
3.1 Common settings
Access:
► Select "Bit/Block Error Rate > General".
State..............................................................................................................................16
Set To Default................................................................................................................17
Save/Recall................................................................................................................... 17
Test Mode......................................................................................................................17
State
Activates the bit error rate measurement.
Remote command:
:BERT:STATe on page 46
:BLER:STATe on page 46
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