Rohde & Schwarz CMW-B400B User manual

R&S®CMW-B400B/-B405A
Audio Measurements
User Manual
User Manual
(;Úß@2)
1176.8116.02 ─ 01
Test & Measurement
深圳德标仪器 135-1095-0799

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)
© 2013 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.
深圳德标仪器 135-1095-0799

Contents
R&S®CMW-B400B/-B405A
3User Manual 1176.8116.02 ─ 01
Contents
1Preface....................................................................................................7
1.1 How to Read Firmware Application Chapters............................................................7
1.1.1 General Description........................................................................................................7
1.1.2 Application Sheets..........................................................................................................7
1.1.3 GUI Reference................................................................................................................8
1.1.4 Programming Examples..................................................................................................8
1.1.5 Command Reference......................................................................................................8
2What'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...............................................................................................22
4GUI Reference .....................................................................................24
4.1 Main View.....................................................................................................................24
4.1.1 Scenario Selection........................................................................................................24
4.1.2 Analog/Digital Meas Tab...............................................................................................26
4.1.3 Speech Analysis Tab....................................................................................................27
4.2 Measurement and Generator Control........................................................................27
4.3 Audio Measurement Settings.....................................................................................28
深圳德标仪器 135-1095-0799

Contents
R&S®CMW-B400B/-B405A
4User Manual 1176.8116.02 ─ 01
4.3.1 General Settings (Analog).............................................................................................29
4.3.2 General Settings (Digital)..............................................................................................31
4.3.3 Single Tone Settings.....................................................................................................32
4.3.4 Multitone Settings..........................................................................................................34
4.3.5 FFT Noise Settings.......................................................................................................36
4.4 Audio Generator Settings...........................................................................................37
4.4.1 General Settings...........................................................................................................37
4.4.2 Single Tone Settings.....................................................................................................38
4.4.3 Multitone Settings..........................................................................................................38
4.4.4 FFT Noise Settings.......................................................................................................40
4.5 Speech Analysis Settings..........................................................................................41
5Programming........................................................................................43
5.1 Audio Measurement and Generator Scenario..........................................................43
5.1.1 Reset and Scenario Selection.......................................................................................43
5.1.2 General Measurement Settings....................................................................................44
5.1.3 Single Tone Measurement............................................................................................44
5.1.4 Multitone Measurement.................................................................................................45
5.1.5 FFT Noise Measurement..............................................................................................46
6Command Reference...........................................................................48
6.1 Conventions and General Information......................................................................48
6.1.1 MEAS<i> and GEN<i>..................................................................................................48
6.1.2 FETCh and READ Commands.....................................................................................48
6.1.3 Current and Statistical Results......................................................................................48
6.1.4 Reliability Indicator........................................................................................................49
6.2 General Settings..........................................................................................................51
6.3 Audio Measurements..................................................................................................52
6.3.1 Measurement Control and States.................................................................................52
6.3.2 General Measurement Settings....................................................................................54
6.3.3 Single Tone Measurement Settings..............................................................................58
6.3.4 Single Tone Measurement Results...............................................................................63
6.3.5 Multitone Measurement Settings...................................................................................66
6.3.6 Multitone Measurement Results....................................................................................68
6.3.7 FFT Noise Measurement Settings................................................................................70
深圳德标仪器 135-1095-0799

Contents
R&S®CMW-B400B/-B405A
5User Manual 1176.8116.02 ─ 01
6.3.8 FFT Noise Measurement Results.................................................................................72
6.4 Audio Generators........................................................................................................74
6.4.1 Generator Control and States.......................................................................................74
6.4.2 General Generator Settings..........................................................................................75
6.4.3 Single Tone Generator Settings....................................................................................75
6.4.4 Multitone Generator Settings........................................................................................76
6.4.5 FFT Noise Generator Settings......................................................................................82
6.5 Speech Analysis..........................................................................................................83
List of Commands................................................................................84
Index......................................................................................................87
深圳德标仪器 135-1095-0799

Contents
R&S®CMW-B400B/-B405A
6User Manual 1176.8116.02 ─ 01
深圳德标仪器 135-1095-0799

Preface
R&S®CMW-B400B/-B405A
7User Manual 1176.8116.02 ─ 01
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.
●Additional user manuals, like this document, describe the firmware applications.
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, e.g. 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 descriptions.
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 mea-
surement applications a detailed description of measurement results and a description
of configurable limits is given, including the relation to conformance requirements defined
in network standard specifications.
1.1.2 Application Sheets
This optional section provides short application examples for select issues and related
background information.
How to Read Firmware Application Chapters
深圳德标仪器 135-1095-0799

Preface
R&S®CMW-B400B/-B405A
8User Manual 1176.8116.02 ─ 01
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 hidden
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 "Command
Reference" is provided. Ranges for numeric parameters and reset values are given there.
For measurement results links to the corresponding command descriptions are provided
(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 application
via a remote-control program and how to retrieve measurement results. The examples
consist of comprehensive command sequences. You can check just a single command
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 command script,
under consideration of dependencies and required orders of the commands.
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 firmware
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
深圳德标仪器 135-1095-0799

What's New in this Revision
R&S®CMW-B400B/-B405A
9User Manual 1176.8116.02 ─ 01
2 What's New in this Revision
This revision describes version 3.2.10 and later of the "Audio Measurement" firmware
application. This is the initial software version.
深圳德标仪器 135-1095-0799

General Description
R&S®CMW-B400B/-B405A
10User Manual 1176.8116.02 ─ 01
3 General Description
The "Audio Analyzer/Generator" option enhances the R&S CMW for audio tests. A single
option (R&S CMW-B400B or R&S CMW-U400) provides an audio board, two analog and
two digital audio generator instances, two analog and two digital audio measurement
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 generate
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 gen-
erator 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, combined
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 frequency
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 signaling application or encodes an audio signal and delivers it
to the signaling application.
Thus the speech codec allows to feed an audio signal into an established RF connection
to the DUT or to extract an audio signal from the RF connection. This is possible for
signaling applications supporting the speech interface.
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.
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 connec-
tors of the R&S CMW.
深圳德标仪器 135-1095-0799

General Description
R&S®CMW-B400B/-B405A
11User Manual 1176.8116.02 ─ 01
The current software version supports only one speech codec, but the audio board hard-
ware 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 provides a
bidirectional interface (encoding and decoding) for a single signaling application instance
at a time.
The following sections describe typical test setups, the basic test procedure, the available
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.
The Sony/Philips Digital Interface (SPDIF) connectors are in line with IEC 60958-3:2010
Consumer.
Test Setups
深圳德标仪器 135-1095-0799

General Description
R&S®CMW-B400B/-B405A
12User Manual 1176.8116.02 ─ 01
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 measure-
ment 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
深圳德标仪器 135-1095-0799

General Description
R&S®CMW-B400B/-B405A
13User Manual 1176.8116.02 ─ 01
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.
Additionally, the DUT is connected to the R&S CMW via an RF connection. A signaling
application is used to set up a voice 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 listens
to the loudspeaker of the DUT and provides the resulting audio signal to an AF IN con-
nector. 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
深圳德标仪器 135-1095-0799

General Description
R&S®CMW-B400B/-B405A
14User Manual 1176.8116.02 ─ 01
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 generators 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 application
is used to set up a voice connection to the DUT.
Fig. 3-4: Test setup for external speech analysis (mono signal)
Test Setups
深圳德标仪器 135-1095-0799

General Description
R&S®CMW-B400B/-B405A
15User Manual 1176.8116.02 ─ 01
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 provides
an audio signal that is routed 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 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 measurements.
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 voice connection / a speech codec, configure the
used signaling application, especially the following settings:
● Activate "Enable Speech"
● Select the speech codec as data source
Then establish the voice connection.
For details refer to the documentation of the used signaling application.
You can access the signaling application from the "Speech Analysis" tab via a softkey.
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:
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 "Config" hot-
key.
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:
Performing Audio Measurements
深圳德标仪器 135-1095-0799

General Description
R&S®CMW-B400B/-B405A
16User Manual 1176.8116.02 ─ 01
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 measure-
ment. So in total there are four audio generators and four audio measurements.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 signaling
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
You can use this filter stage to eliminate a possible DC component in the audio signal
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.
AF Filter Settings
深圳德标仪器 135-1095-0799

General Description
R&S®CMW-B400B/-B405A
17User Manual 1176.8116.02 ─ 01
Several weighting filters with different shape have been standardized. The following
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 "Bandpass
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 weighting
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
●Modifying Diagrams................................................................................................22
●Using Markers.........................................................................................................22
●Common View Elements.........................................................................................22
Measurement Results
深圳德标仪器 135-1095-0799

General Description
R&S®CMW-B400B/-B405A
18User Manual 1176.8116.02 ─ 01
3.4.1 Single Tone Results
To perform a harmonics measurement, a fixed frequency sine wave audio test tone (sin-
gle tone) is transmitted. Harmonics are signals at an integer multiple of the fundamental
frequency. The nth harmonic is n times the frequency of the fundamental wave. The pro-
duction 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 33
●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 digital
measurement.
Fig. 3-6: Analog single tone result table
Fig. 3-7: Digital single tone result table
Measurement Results
深圳德标仪器 135-1095-0799

General Description
R&S®CMW-B400B/-B405A
19User Manual 1176.8116.02 ─ 01
Table rows
The table rows provide the following results:
●THD:
Total Harmonic Distortion, ratio of the harmonic distortion voltage to the fundamental
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 per-
cent.
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 22.
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. It can be hidden/shown
via the softkey/hotkey combination "Digital Meas" > "Spectrum Off/On" and via the single
tone measurement settings, see "Spectrum" on page 34.
Measurement Results
深圳德标仪器 135-1095-0799

General Description
R&S®CMW-B400B/-B405A
20User Manual 1176.8116.02 ─ 01
Fig. 3-8: Single tone spectrum diagram
The diagram shows the measured audio level vs. the frequency. A rectangular window
with constant weighting is used.
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 config-
urable.
You can display the results in a bar graph or alternatively in a table.
Fig. 3-9: Multitone result diagram
The bar graph displays the audio levels measured at the frequencies of the individual test
tones. The labels of the individual bars correspond to the numbers of the test tones in
the generator settings.
The audio levels can be displayed either as dB values, relative to the level of a selected
test tone or as absolute levels. The current setting is displayed at the top. You can con-
figure it via the softkey/hotkey combination "Display Multitone" > "Result Mode" or via the
multitone settings of the measurement, see "Result Mode" on page 35.
To switch between the table view and the diagram view, use the softkey/hotkey combi-
nation "Display Multitone" > "View Diagr./Table".
Measurement Results
深圳德标仪器 135-1095-0799