Rohde & Schwarz CMW-B400B User manual

R&S®CMW-B400B/-B405A
Audio Measurements
User Manual
User Manual
1176.8116.02 ─ 04
(;Úß@2)
Test & Measurement
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This user manual describes the following R&S®CMW options:
●R&S®CMW-B400B (Audio analyzer/generator, for new units and units delivered after September 2011)
●R&S®CMW-U400 (Audio analyzer/generator, for units delivered before September 2011)
●R&S®CMW-B405A (Speech codec)
© 2015 Rohde & Schwarz GmbH & Co. KG
Mühldorfstr. 15, 81671 München, Germany
Phone: [phone] - 0
Fax: [phone]
E-mail: [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.
The following abbreviations are used throughout this manual: R&S®CMW is abbreviated as R&S CMW.
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Contents
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Contents
1 Preface.................................................................................................... 7
1.1 How to Read Firmware Application Chapters............................................................ 7
1.1.1 General Description........................................................................................................ 7
1.1.2 Application Sheets.......................................................................................................... 8
1.1.3 GUI Reference................................................................................................................ 8
1.1.4 Programming Examples..................................................................................................8
1.1.5 Command Reference...................................................................................................... 8
2 What's New in this Revision..................................................................9
3 General Description.............................................................................10
3.1 Test Setups..................................................................................................................11
3.1.1 Audio Connectors..........................................................................................................11
3.1.2 Test Setup for Audio Measurement and Generator...................................................... 12
3.1.3 Test Setup for Microphone- and Speaker Test............................................................. 13
3.1.4 Test Setup for External Speech Analysis......................................................................14
3.2 Performing Audio Measurements..............................................................................15
3.3 AF Filter Settings........................................................................................................ 16
3.4 Measurement Results................................................................................................. 17
3.4.1 Single Tone Results...................................................................................................... 18
3.4.2 Multitone Results...........................................................................................................20
3.4.3 FFT Noise Results........................................................................................................ 21
3.4.4 Modifying Diagrams...................................................................................................... 22
3.4.5 Using Markers............................................................................................................... 22
3.4.6 Common View Elements...............................................................................................23
4 GUI Reference ..................................................................................... 24
4.1 Main View.....................................................................................................................24
4.1.1 Scenario Selection........................................................................................................ 25
4.1.2 Analog/Digital Meas Tab............................................................................................... 26
4.1.3 Speech Analysis Tab.................................................................................................... 27
4.2 Measurement and Generator Control........................................................................29
4.3 Audio Measurement Settings.....................................................................................30
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4.3.1 General Settings (Analog).............................................................................................30
4.3.2 General Settings (Digital).............................................................................................. 33
4.3.3 Single Tone Settings..................................................................................................... 34
4.3.4 Multitone Settings..........................................................................................................37
4.3.5 FFT Noise Settings....................................................................................................... 38
4.4 Audio Generator Settings...........................................................................................40
4.4.1 General Settings........................................................................................................... 40
4.4.2 Single Tone Settings..................................................................................................... 41
4.4.3 Multitone Settings..........................................................................................................41
4.4.4 FFT Noise Settings....................................................................................................... 44
4.5 Speech Analysis Settings.......................................................................................... 44
4.6 Additional Softkeys and Hotkeys.............................................................................. 46
5 Programming........................................................................................47
5.1 Audio Measurement and Generator Scenario.......................................................... 47
5.1.1 Reset and Scenario Selection.......................................................................................47
5.1.2 General Measurement Settings.................................................................................... 48
5.1.3 Single Tone Measurement............................................................................................ 48
5.1.4 Multitone Measurement.................................................................................................49
5.1.5 FFT Noise Measurement.............................................................................................. 51
6 Command Reference........................................................................... 52
6.1 Conventions and General Information......................................................................52
6.1.1 MEAS<i> and GEN<i>.................................................................................................. 52
6.1.2 FETCh and READ Commands..................................................................................... 52
6.1.3 Current and Statistical Results......................................................................................52
6.1.4 Keywords...................................................................................................................... 53
6.1.5 Reliability Indicator........................................................................................................ 53
6.2 General Settings..........................................................................................................56
6.3 Audio Measurements..................................................................................................58
6.3.1 Measurement Control and States................................................................................. 58
6.3.2 General Measurement Settings.................................................................................... 60
6.3.3 Single Tone Measurement Settings.............................................................................. 65
6.3.4 Single Tone Measurement Results............................................................................... 71
6.3.5 Multitone Measurement Settings...................................................................................74
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6.3.6 Multitone Measurement Results....................................................................................76
6.3.7 FFT Noise Measurement Settings................................................................................ 78
6.3.8 FFT Noise Measurement Results................................................................................. 79
6.4 Audio Generators........................................................................................................82
6.4.1 Generator Control and States....................................................................................... 82
6.4.2 General Generator Settings.......................................................................................... 82
6.4.3 Single Tone Generator Settings....................................................................................83
6.4.4 Multitone Generator Settings........................................................................................ 84
6.4.5 FFT Noise Generator Settings...................................................................................... 90
6.5 Speech Analysis..........................................................................................................90
List of Commands................................................................................93
Index......................................................................................................97
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Preface
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1 Preface
The operation of the R&S CMW is described in several user manuals:
●The R&S CMW user manual describes the base software, common features of the
firmware applications and basic principles for manual operation and remote control.
There is a separate manual version for each R&S CMW model.
●Additional user manuals, like this document, describe the firmware applications.
There is only one version of these manuals for all R&S CMW models.
Rohde & Schwarz provides registered users a "CMW Customer Web" section on
GLORIS, the Global Rohde & Schwarz Information System: https://extranet.rohde-
schwarz.com. From this resource, you can download software updates, waveform
library updates and documentation updates, for example updates of this document.
1.1 How to Read Firmware Application Chapters
Each firmware application is described in a separate chapter. These chapters can be
read independently of each other. However, they are all organized as follows:
1. General Description
2. Application Sheets (optional)
3. GUI Reference
4. Programming Examples
5. Command Reference
The chapters "System Overview" and "Remote Control" in the R&S CMW user manual
provide additional important information independent of the individual firmware applica-
tions. The most important parts are referenced by the firmware application descrip-
tions.
1.1.1 General Description
This section provides a general description of the firmware application, independent of
a specific operation mode (manual or remote control). It gives a high-level introduction
to the capabilities of the firmware application. Background information related to the
network standard is given as far as it is directly related to administrable parameters.
For measurement applications a detailed description of measurement results and a
description of configurable limits is given, including the relation to conformance require-
ments defined in network standard specifications.
How to Read Firmware Application Chapters
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1.1.2 Application Sheets
This optional section provides short application examples for select issues and related
background information.
1.1.3 GUI Reference
The GUI reference describes the manual operation of the firmware application via the
Graphical User Interface (GUI).
The description of a configuration dialog usually starts with a screenshot presenting the
preset values of the parameters (sometimes preset values are modified to enable hid-
den parts of a dialog). Below the screenshot all shown parameters are described. For
each single parameter a link to the corresponding command description in the "Com-
mand Reference" is provided. Ranges for numeric parameters and reset values are
given there.
For measurement results links to the corresponding command descriptions are provi-
ded (commands to retrieve the results). The measurement results are described in
detail in the "General Description".
1.1.4 Programming Examples
The programming examples show how to control and configure the firmware applica-
tion via a remote-control program and how to retrieve measurement results. The exam-
ples consist of comprehensive command sequences. You can check just a single com-
mand of a sequence to get an example for the syntax of this single command. But you
can also consider an entire sequence showing the commands in the context of a com-
mand script, under consideration of dependencies and required orders of the com-
mands.
The command sequences are written with the intention to list most commands of the
firmware application. They do not show the fastest way for a given configuration task.
The fastest way would use many reset values and omit the corresponding commands.
The examples are referenced by the command descriptions of the "Command Refer-
ence".
1.1.5 Command Reference
The command reference provides information on the remote commands of the firm-
ware application. The commands are grouped according to their function.
Each command description indicates the syntax of the command header and of the
parameters. For input parameters the allowed ranges, reset values and default units
are listed, for returned values the expected ranges and default units. Most commands
have a command form and a query form. Exceptions are marked by "Setting only",
"Query only" or "Event". Furthermore a link to the "Programming Examples" is provided
and the first software version supporting the command is indicated.
How to Read Firmware Application Chapters
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What's New in this Revision
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2 What's New in this Revision
This revision describes version 3.5.10 and later of the "Audio Measurement" firmware
application. Compared to version 3.2.30, it provides the following new features and
changes:
●Speech analysis enhancements:
–Changed coupling between speech codec and signaling application. The set-
ting "Enable Speech Codec" is removed from the signaling applications. The
coupled application is now selected in the audio measurement settings, see
Speech Analysis Settings.
– Event log and information provided by coupled master application, see Speech
Analysis Tab
– The clock of the audio board can be adjusted, see Clock Drift
●Scenario selection improvements:
– New commands, one command per scenario, see General Settings
– The scenario is selectable per audio application instance.
●Support of STATus:OPERation registers, with the following register paths:
– STATus:OPERation:TASK:A:AUDio:GENerator<i>:ANALog | DIGital
– STATus:OPERation:TASK:A:AUDio:MEASurement<i>:ANALog | DIGital
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General Description
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3 General Description
The "Audio Analyzer/Generator" option enhances the R&S CMW for audio tests. A sin-
gle option (R&S CMW-B400B or R&S CMW-U400) provides an audio board, two ana-
log and two digital audio generator instances, two analog and two digital audio mea-
surement instances, four analog AF connectors at the front panel and two digital
SPDIF connectors at the rear panel.
You can use all generator and measurement instances in parallel. So you can gener-
ate and measure two analog mono audio test signals and two digital mono audio test
signals in parallel. You can also generate and measure a stereo signal by combining
two generator and measurement instances.
The tests cover the following audio signal properties:
●Characteristics of a single tone signal, for example Total Harmonic Distortion
(THD), Signal to Noise and Distortion ratio (SINAD) and Signal to Noise Ratio
(SNR).
●Audio levels of up to 20 single tones at configurable frequencies and levels, com-
bined to a multitone signal.
●Audio level vs. frequency for a noise signal, consisting of several thousand single
tones. The noise signal has a very low crest factor. It is ideal to analyze the fre-
quency response of a DUT over the entire audio frequency range, with a single
measurement.
Two audio analyzer and generator options are available. They provide the same test
functionality. Which option is required, depends on your instrument:
●Option R&S CMW-B400B "Audio Analyzer/Generator" is compatible to R&S CMW
delivered after September 2011. It is also compatible to R&S CMW delivered
before September 2011, that have been upgraded with R&S CMW-U5024.
●Option R&S CMW-U400 "Audio Analyzer/Generator" is compatible to R&S CMW
delivered before September 2011, that have not been upgraded with R&S CMW-
U5024.
Optional speech codec
Optionally, the audio board can be enhanced with a speech codec (R&S CMW-
B405A).
A speech codec provides an interface to the signaling units of the R&S CMW. It
decodes the signal delivered by a controlling application or encodes an audio signal
and delivers it to the controlling application.
Thus the speech codec allows to feed an audio signal into an established RF connec-
tion to the DUT or to extract an audio signal from the RF connection. The controlling
application can be a signaling application, the IMS server of the DAU (for VoLTE) or a
protocol test application.
The audio signal can be generated and analyzed internally using the digital audio gen-
erator and measurement. This allows for example microphone- and speaker tests for a
mobile phone.
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For speech quality analysis of a mobile phone, the audio signal must be generated and
analyzed by an external audio analyzer (e.g. R&S UPV) connected to the audio con-
nectors of the R&S CMW.
The current software version supports only one speech codec, but the audio board
hardware is ready for two speech codecs. For future software releases, the full support
of two independently operating speech codecs is planned. A single speech codec pro-
vides a bidirectional interface (encoding and decoding) for a single controlling applica-
tion instance at a time.
The following sections describe typical test setups, the basic test procedure, the availa-
ble filters and the measurement results.
3.1 Test Setups
The following sections provide an overview of the audio connectors and of typical test
setups for the individual scenarios.
●Audio Connectors....................................................................................................11
●Test Setup for Audio Measurement and Generator................................................ 12
●Test Setup for Microphone- and Speaker Test....................................................... 13
●Test Setup for External Speech Analysis................................................................14
3.1.1 Audio Connectors
An R&S CMW with an installed audio board provides AF connectors for analog audio
signals at the front panel and SPDIF connectors for digital audio signals at the rear
panel.
AF connectors
Connector AF 1 IN and AF 2 IN are used for input of analog audio signals, AF 1 OUT
and AF 2 OUT for output of analog audio signals.
SPDIF connectors
Connector SPDIF IN is used for input of digital audio signals, SPDIF OUT for output of
digital audio signals. A digital signal can contain two multiplexed channels, SPDIF-L
and SPDIF-R.
Test Setups
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The Sony/Philips Digital Interface (SPDIF) connectors are in line with IEC
60958-3:2010 Consumer.
Connector selection
Whether AF 1 or AF 2 / SPDIF-L or SPDIF-R are used, depends on the instance (1 or
2) of the audio application and on the sub-instrument configuration of the instrument
(all resources in one sub-instrument or instrument split into two sub-instruments), as
shown in the following table.
Table 3-1: Audio connector usage depending on instance / sub-instrument
One Sub-Instrument Two Sub-Instruments
AF 1, SPDIF-L instance 1 sub-instrument 1
AF 2, SPDIF-R instance 2 sub-instrument 2
3.1.2 Test Setup for Audio Measurement and Generator
The scenario "Audio Measurement and Generator" generally involves both an audio
generator and an audio measurement. The generator provides an audio signal at an
AF OUT or SPDIF OUT connector. The signal is routed to the DUT, passes the DUT
and is routed back to an AF IN or SPDIF IN connector. Then the signal is analyzed via
the audio measurement. The generator and the measurement are coupled, so that the
measurement knows the generator settings and thus the properties of the generated
signal.
A typical use case would be to analyze the frequency response of an amplifier.
Fig. 3-1: Test setup for analog or digital DUT, coupled measurement and generator
You can freely combine analog and digital applications. You may for example couple
an analog generator and a digital measurement to test an A/D converter, or vice-versa
to test a D/A converter.
Test Setups
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Fig. 3-2: Test setup for A/D or D/A converter, coupled measurement and generator
Single tone measurements can also be performed without using the audio generator.
In that case only an audio connection from the DUT to an AF IN or SPDIF IN connector
is required.
3.1.3 Test Setup for Microphone- and Speaker Test
The scenario "Microphone- and Speakertest" is designed for tests of the microphone
and speaker built into a DUT, for example a mobile phone.
Only audio measurements can be performed with this scenario. For speech quality
tests, additional external equipment is required, see chapter 3.1.4, "Test Setup for
External Speech Analysis", on page 14.
The DUT is typically attached to an artificial head, providing an artificial mouth (loud-
speaker) and ear (microphone). Alternatively, a reference loudspeaker and microphone
can be used. The DUT may also support a direct electrical coupling. For basic funtional
tests, you can also use the handset R&S CMW-Z50. It provides a speaker and micro-
phone and can be connected to AF IN and AF OUT.
Additionally, the DUT is connected to the R&S CMW via an RF connection. A signaling
application is used to set up a speech connection to the DUT. A speech codec is also
required (R&S CMW-B405A).
For speaker tests, the digital audio generator provides an audio signal that is encoded,
modulated and routed via the RF connection to the DUT. The DUT demodulates and
decodes the signal and sends the audio signal to its loudspeaker. The artificial ear lis-
tens to the loudspeaker of the DUT and provides the resulting audio signal to an AF IN
connector. The R&S CMW analyzes the signal with the analog audio measurement.
For microphone tests, the analog audio generator provides an audio signal that is
routed via an AF OUT connector to the artificial mouth. The DUT listens to the artificial
mouth, encodes and modulates the audio signal and transmits it via the RF connection
to the R&S CMW. The R&S CMW demodulates and decodes the signal and analyzes it
with the digital audio measurement.
Test Setups
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Fig. 3-3: Test setup for microphone and speaker test
If your DUT supports electrical coupling, you can test the speaker and the microphone
simultaneously. If you use acoustical coupling, it is recommended to test speaker and
microphone one after another (switch on only one generator at a time), so that the two
acoustical couplings at the DUT can not interfere with each other.
3.1.4 Test Setup for External Speech Analysis
The scenarios "External Analog Speech Analysis" and "External Digital Speech Analy-
sis" are designed for external analysis of the speech quality of a mobile phone.
The typical test setup is similar to a "Microphone- and Speaker Test" setup, with the
audio generators and measurements located in an external audio analyzer supporting
speech quality analysis, for example the R&S UPV or the R&S UPP. The audio gener-
ators and measurements of the R&S CMW do not support speech analysis and are not
used.
So the setup comprises an external audio analyzer (e.g. R&S UPV), an R&S CMW, the
DUT and in the case of acoustical coupling, an artificial head. The audio board must be
equipped with a speech codec (R&S CMW-B405A). An R&S CMW signaling applica-
tion is used to set up a speech connection to the DUT.
Fig. 3-4: Test setup for external speech analysis (mono signal)
Test Setups
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General Description
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To test the speech quality of the speaker path, an external audio generator provides an
audio signal that is routed to an AF IN or SPDIF IN connector. The audio signal is
encoded and modulated in the R&S CMW and routed via the RF connection to the
DUT. The DUT demodulates and decodes the signal and sends the audio signal to its
loudspeaker. The artificial ear listens to the loudspeaker of the DUT and provides the
resulting audio signal to the external audio analyzer.
To test the speech quality of the microphone path, an external audio generator pro-
vides an audio signal that is routed to the artificial mouth. The DUT listens to the artifi-
cial mouth, encodes and modulates the audio signal and transmits it via the RF con-
nection to the R&S CMW. The R&S CMW demodulates and decodes the signal and
routes it via an AF OUT or SPDIF OUT connector to the external audio analyzer.
If supported by the external audio analyzer, it is recommended to use a digital setup
(use the SPDIF connectors and the scenario "External Digital Speech Analysis"). A
digital setup provides a higher accuracy than an analog setup.
3.2 Performing Audio Measurements
The required settings vary depending on the used scenario, the used type of audio test
signal and the test setup components.
However, the general procedure outlined below is applicable to all audio measure-
ments.
1. Connect the components of your test setup (see chapter 3.1, "Test Setups",
on page 11).
2. In the audio application main view, at the top, select a scenario matching your test
setup.
3. If your test setup involves an RF speech connection / a speech codec:
a) On the "Speech Analysis" tab, select the application that will set up the speech
call ("Controlled by" setting).
Softkeys related to the controlling application are added to the softkey bar.
b) Establish a speech connection via the controlling application. You can use the
softkeys to access settings of the controlling application and to control the call
setup, see chapter 4.6, "Additional Softkeys and Hotkeys", on page 46.
In most signaling applications, you must select "Speech" as data source.
For LTE speech calls, you must configure the IMS server of the DAU for audio
tests.
For details, refer to the documentation of the controlling application.
4. If your test setup involves external equipment, configure it (for example an R&S
UPV).
5. If your test setup involves internal audio generators and measurements, configure
them:
Performing Audio Measurements
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All generator and measurement settings are included in a single dialog box. To
open it, select the "Analog Meas" tab or the "Digital Meas" tab and press the "Con-
fig" hotkey.
Configure first the used generators. Especially select a signal type and configure
the measurement coupling. Then configure the measurements.
6. Turn on the used internal/external generator(s).
To turn on an internal generator, proceed as follows:
a) Select the "Analog Meas" tab or "Digital Meas" tab.
b) Select the relevant generator softkey ("Analog Generator" or "Digital Genera-
tor").
c) Press "ON | OFF" and wait until the generator softkey indicates the "ON" state
and the hour glass symbol has disappeared.
7. Start the internal/external audio measurement(s).
To start an internal measurement, proceed as follows:
a) Select the tab of the measurement to be started ("Analog Meas" or "Digital
Meas").
b) Select the measurement softkey ("Analog Meas" or "Digital Meas").
c) Press "ON | OFF" to start the measurement.
The measurement results are displayed in the measurement tab.
Parallel measurements
One audio board supports two audio application instances. And each instance provides
an analog generator, a digital generator, an analog measurement and a digital mea-
surement. So in total there are four audio generators and four audio measure-
ments.You can use all these resources in parallel, for example to test several DUTs in
parallel or to perform stereo tests.
If your test setup contains more than one acoustic coupling, it is recommended to use
only one coupling at a time, so that they do not interfer. That means, transmit an audio
signal only via one coupling at a time.
Example: If both the microphone and the speaker of a DUT are coupled to the test
setup acoustically, test the speaker path and the microphone path one after the other.
Activate the audio generator of only one path at a time.
If the audio board is equipped with a single speech codec, this codec can be used by
the first instance of the audio application. Each codec can be coupled to only one sig-
naling application at a time.
3.3 AF Filter Settings
The AF input path of the audio measurements provides the following configurable filter
stages which affect the AF results:
●Lowpass filter with a cutoff frequency of 3 kHz, 4 kHz or 15 kHz
●Highpass filter with a cutoff frequency of 6 Hz, 50 Hz or 300 Hz
AF Filter Settings
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You can use this filter stage to eliminate a possible DC component in the audio sig-
nal that may cause measurement inaccuracies.
●Weighting filter
The human ear is a nonlinear sensor. Its sensitivity depends on the frequency.
Weighting filters take this into account by deemphasizing very low and very high
frequency components to which the human ear is less sensitive.
Several weighting filters with different shape have been standardized. The follow-
ing filters are supported:
–A-weighting filter defined in IEC 61672. The A-weighted scale is commonly
used in local ordinances and standards.
–CCITT weighting filter defined in ITU-T Rec. O.41 (also known as ITU-T P53
filter). This filter is used for international telephone circuits.
– C-message weighting filter defined in IEEE 743. This filter is used for North
American telephone circuits.
●Bandpass filter with configurable center frequency and bandwidth. This filter can
not be disabled and is only relevant for the single tone measurement result "Band-
pass Level".
The following figure provides an overview of the filter positions in the input path and of
the measurement points for the individual results. The lowpass, highpass and weight-
ing filter can be disabled separately.
Fig. 3-5: Input path filters and results
3.4 Measurement Results
All results of an audio measurement are displayed in a single tab. There is one tab for
analog measurements and one tab for digital measurements.
For scenarios that do not involve an audio measurement, the tabs are hidden (for
example external speech analysis).
The following sections describe the results for the individual signal types.
●Single Tone Results................................................................................................18
●Multitone Results.....................................................................................................20
●FFT Noise Results.................................................................................................. 21
Measurement Results
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●Modifying Diagrams................................................................................................ 22
●Using Markers.........................................................................................................22
●Common View Elements.........................................................................................23
3.4.1 Single Tone Results
To perform a harmonics measurement, a fixed frequency sine wave audio test tone
(single tone) is transmitted. Harmonics are signals at an integer multiple of the funda-
mental frequency. The nth harmonic is n times the frequency of the fundamental wave.
The production of harmonic frequencies by an electronic system is known as harmonic
distortion.
The measured power of the demodulated audio signal has three components:
●Signal S: power of the audio signal at the configured reference frequency, see
"Filter > Distortion Frequency" on page 35
●Distortion D: sum of the signal powers of the 2nd, 3rd, 4th ... harmonics
The R&S CMW measures up to 10 harmonics at frequencies up to 21 kHz.
●Noise N: power of the noise floor
The sum of all three components S + N + D is the total received audio power. S and D
can be obtained in frequency-selective measurements. To obtain the sum N + D, the
R&S CMW uses a notch filter to eliminate the fundamental wave. To avoid suppression
of the higher harmonics, the bandwidth of the notch filter is automatically adjusted to
be smaller than the reference frequency.
Most results of a single tone measurement are calculated from the measured S, N and
D. The following figures show the result tables of an analog measurement and of a dig-
ital measurement.
Fig. 3-6: Analog single tone result table
Measurement Results
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Fig. 3-7: Digital single tone result table
Table rows
The table rows provide the following results:
●THD:
Total Harmonic Distortion, ratio of the harmonic distortion voltage to the fundamen-
tal wave voltage, in percent and as dB value.
THD [%] = sqrt (D / S) * 100
THD [dB] = 20 * log (sqrt (D / S)) = 10 * log (D / S)
The R&S CMW displays THD [%] values up to 100 %. A result close to 100% may
indicate incorrect settings, e.g. a specified reference frequency which differs from
the actual frequency of the transmitted test tone.
●THD + N:
Total Harmonic Distortion and Noise, ratio of the measured AF signal voltage with
a notched-out fundamental wave to the complete measured AF signal voltage, in
percent.
THD + N [%] = sqrt (N + D) / sqrt (S + N + D) * 100
●SINAD:
Signal to Noise And Distortion, ratio of the complete measured AF signal voltage to
the measured AF signal with a notched-out fundamental wave, as dB value.
SINAD [dB] = 20 * log (sqrt (S + N + D) / sqrt (N + D))
●SNR:
Signal to Noise Ratio, ratio of the signal power to the noise power, as dB value.
SNR [dB] = 20 * log (sqrt(S / N)) = 10 * log (S / N)
●DC Level:
DC component of the measured analog AF signal in V
●Frequency:
Frequency of the measured analog AC signal
●Weighted / Bandpass Level, RMS:
Effective (RMS-averaged) value of the AC component of the measured AF signal,
measured in the weighting filter path / the bandpass filter path.
Table columns
The table columns provide a statistical evaluation of the results, see "Statistical results"
on page 23.
Measurement Results
深圳德标仪器 135-1095-0799

General Description
R&S®CMW-B400B/-B405A
20User Manual 1176.8116.02 ─ 04
The column "EXT" provides either minimum or maximum values, depending on the
result:
●Maximum: THD, THD + N, frequency, weighted level, bandpass level
●Minimum: SINAD, SNR
●Maximum or minimum, whichever has the larger magnitude: DC level
Spectrum diagram
The single tone measurement provides also a spectrum diagram. The measurement of
spectrum results can be enabled via the softkey/hotkey combination "Analog/Digital
Meas" > "Spectrum Off/On" and via the single tone measurement settings, see "Spec-
trum > Off / On" on page 37.
Fig. 3-8: Single tone spectrum diagram
The diagram shows the measured audio level vs. the frequency. The results are mea-
sured in the time domain and transformed to the frequency domain via a Fast Fourier
Transformation (FFT). Prior to the FFT, a configurable window function is applied to
the raw data in order to reduce side-effects of the FFT. For selection of the window
function, see "Filter > Window Function" on page 35.
3.4.2 Multitone Results
For a multitone measurement, an audio signal comprising up to 20 sine wave test
tones is generated, transmitted and analyzed. The frequency and level of each tone is
configurable.
You can display the results in a bar graph or alternatively in a table.
Measurement Results
深圳德标仪器 135-1095-0799