R&S®FSW-K18
Power Amplifier and Envelope
Tracking Measurements
User Manual
(;Úðë2)
1176989302
Version 22
This manual applies to the following R&S®FSW models with firmware version 5.10 and later:
●
R&S®FSW8 (1331.5003K08 / 1312.8000K08)
●
R&S®FSW13 (1331.5003K13 / 1312.8000K13)
●
R&S®FSW26 (1331.5003K26 / 1312.8000K26)
●
R&S®FSW43 (1331.5003K43 / 1312.8000K43)
●
R&S®FSW50 (1331.5003K50 / 1312.8000K50)
●
R&S®FSW67 (1331.5003K67 / 1312.8000K67)
●
R&S®FSW85 (1331.5003K85 / 1312.8000K85)
The following firmware options are described:
●
R&S®FSW-K18 (1325.2170.02)
●
R&S®FSW-K18D (1331.6845.02)
●
R&S®FSW-K18F (1338.7230.02)
●
R&S®FSW-K18M (1345.1470.02)
© 2022 Rohde & Schwarz GmbH & Co. KG
Muehldorfstr. 15, 81671 Muenchen, Germany
Phone: +49 89 41 29 - 0
Email: info@rohde-schwarz.com
Internet: www.rohde-schwarz.com
Subject to change – data without tolerance limits is not binding.
R&S® is a registered trademark of Rohde & Schwarz GmbH & Co. KG.
Trade names are trademarks of the owners.
1176.9893.02 | Version 22 | R&S®FSW-K18
Throughout this manual, products from Rohde & Schwarz are indicated without the ® symbol , e.g. R&S®FSW is indicated as
R&S FSW.
R&S®FSW-K18
1 Welcome to the amplifier measurement application.......................... 9
1.1 Starting the application................................................................................................ 9
1.2 Understanding the display information.................................................................... 10
2 Measurements and result displays.................................................... 12
3 Configuration........................................................................................39
3.1 Configuration overview.............................................................................................. 39
3.2 Performing measurements.........................................................................................41
3.3 Designing a reference signal..................................................................................... 42
3.4 Configuring inputs and outputs.................................................................................54
3.4.1 Selecting and configuring the input source................................................................... 54
Contents
Contents
3.4.1.1 Configuring the RF input............................................................................................... 55
3.4.1.2 External mixer............................................................................................................... 57
3.4.1.3 Configuring the analog baseband input........................................................................ 57
3.4.1.4 I/Q file............................................................................................................................59
3.4.2 Configuring the frequency............................................................................................. 60
3.4.3 Defining level characteristics.........................................................................................62
3.4.4 Power sensors.............................................................................................................. 66
3.4.5 Using probes................................................................................................................. 71
3.4.6 Configuring outputs....................................................................................................... 71
3.4.7 Controlling a signal generator....................................................................................... 72
3.4.8 Configuring the 2 GHz or 5 GHz bandwidth extension................................................. 76
3.4.9 Reference: I/Q file input................................................................................................ 77
3.4.9.1 Basics on input from I/Q data files................................................................................ 77
3.4.9.2 I/Q data file format (iq-tar)............................................................................................. 78
I/Q parameter XML file specification............................................................................. 79
I/Q data binary file......................................................................................................... 84
3.5 Triggering measurements.......................................................................................... 87
3.6 Configuring the data capture..................................................................................... 87
3.7 Sweep configuration...................................................................................................91
3.8 Synchronizing measurement data.............................................................................92
3.9 Evaluating measurement data................................................................................... 94
3User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
3.10 Estimating and compensating signal errors............................................................ 96
3.11 Equalizer...................................................................................................................... 97
3.12 Applying system models............................................................................................99
3.13 Applying digital predistortion.................................................................................. 101
3.13.1 Polynomial DPD.......................................................................................................... 102
3.13.2 Direct DPD (R&S FSW-K18D).................................................................................... 104
3.13.3 Memory polynomial DPD (R&S FSW-K18M).............................................................. 109
3.13.4 Hammerstein model (R&S FSW-K18M)...................................................................... 111
3.14 Configuring envelope measurements..................................................................... 113
3.15 Configuring power measurements.......................................................................... 115
3.16 Configuring adjacent channel leakage error (ACLR) measurements.................. 116
3.17 Configuring the parameter sweep........................................................................... 119
Contents
4 Analysis.............................................................................................. 123
4.1 Configuring traces.................................................................................................... 123
4.1.1 Selecting the trace information....................................................................................123
4.1.2 Exporting traces.......................................................................................................... 126
4.1.3 Detector settings......................................................................................................... 127
4.2 Using markers........................................................................................................... 128
4.2.1 Configuring markers....................................................................................................128
4.2.2 Configuring individual markers....................................................................................129
4.2.3 Positioning markers.....................................................................................................131
4.3 Customizing numerical result tables...................................................................... 132
4.4 Configuring result display characteristics............................................................. 134
4.5 Scaling the X-Axis.....................................................................................................136
4.6 Scaling the Y-Axis.....................................................................................................138
5 Remote control commands for amplifier measurements...............140
5.1 Introduction............................................................................................................... 140
5.1.1 Conventions used in descriptions............................................................................... 141
5.1.2 Long and short form.................................................................................................... 142
5.1.3 Numeric suffixes..........................................................................................................142
5.1.4 Optional keywords.......................................................................................................142
5.1.5 Alternative keywords................................................................................................... 143
5.1.6 SCPI parameters.........................................................................................................143
4User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
5.1.6.1 Numeric values........................................................................................................... 143
5.1.6.2 Boolean....................................................................................................................... 144
5.1.6.3 Character data............................................................................................................ 145
5.1.6.4 Character strings.........................................................................................................145
5.1.6.5 Block data................................................................................................................... 145
5.2 Common suffixes...................................................................................................... 145
5.3 Selecting the application..........................................................................................146
5.4 Configuring the screen layout................................................................................. 150
5.5 Performing amplifier measurements.......................................................................158
5.5.1 Performing measurements..........................................................................................158
5.5.2 Retrieving graphical measurement results..................................................................162
5.5.3 Retrieving numeric results...........................................................................................164
5.5.3.1 Retrieving general numeric results..............................................................................165
Contents
5.5.3.2 Retrieving results of the result summary.....................................................................165
Retrieving all results....................................................................................................165
Retrieving the modulation accuracy............................................................................ 166
Retrieving power results..............................................................................................170
Retrieving baseband characteristics........................................................................... 177
5.5.3.3 Retrieving results of the parameter sweep table.........................................................180
5.5.3.4 Retrieving results of the statistics table.......................................................................194
Amplitude droop.......................................................................................................... 195
AM/AM curve width..................................................................................................... 196
AM/PM curve width..................................................................................................... 197
Average PAE...............................................................................................................198
Power (Vcc*Icc)...........................................................................................................201
Crest factor input.........................................................................................................204
Crest factor out............................................................................................................205
Frequency error...........................................................................................................206
Gain.............................................................................................................................207
Gain imbalance........................................................................................................... 208
Current (Icc)................................................................................................................ 209
I/Q imbalance.............................................................................................................. 212
I/Q offset......................................................................................................................213
5User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Contents
Baseband i input voltage.............................................................................................214
Magnitude error...........................................................................................................217
P1DB input.................................................................................................................. 218
P1DB output................................................................................................................219
P2DB input.................................................................................................................. 220
P2DB output................................................................................................................221
P3DB input.................................................................................................................. 222
P3DB output................................................................................................................223
Average power consumption.......................................................................................224
PC based average PAE...............................................................................................225
Phase error................................................................................................................. 226
Power input................................................................................................................. 227
Power output............................................................................................................... 230
Quadrature error......................................................................................................... 233
Baseband q input voltage............................................................................................234
Raw EVM.................................................................................................................... 237
Raw model EVM......................................................................................................... 240
Sample rate error........................................................................................................ 243
Voltage (Vcc)...............................................................................................................244
5.5.4 Retrieving I/Q data...................................................................................................... 247
5.6 Configuring amplifier measurements..................................................................... 248
5.6.1 Designing a reference signal.......................................................................................249
5.6.2 Selecting and configuring the input source................................................................. 264
5.6.3 Power sensor measurements..................................................................................... 271
5.6.3.1 Configuring power sensor measurements.................................................................. 271
5.6.3.2 Triggering with power sensors.................................................................................... 280
5.6.4 Configuring the frequency........................................................................................... 283
5.6.5 Defining level characteristics.......................................................................................284
5.6.6 Controlling a signal generator..................................................................................... 290
5.6.7 Configuring the data capture.......................................................................................300
5.6.8 Sweep configuration....................................................................................................305
5.6.9 Synchronizing measurement data...............................................................................307
5.6.10 Defining the evaluation range..................................................................................... 310
6User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
5.6.11 Estimating and compensating signal errors................................................................ 312
5.6.11.1 Error estimation and compensation............................................................................ 312
5.6.11.2 Equalizer..................................................................................................................... 315
5.6.12 Applying a system model............................................................................................ 317
5.6.13 Applying digital predistortion....................................................................................... 320
5.6.14 Configuring envelope tracking.....................................................................................338
5.6.15 Configuring ACLR measurements.............................................................................. 339
5.6.16 Configuring power measurements.............................................................................. 344
5.6.17 Configuring parameter sweeps................................................................................... 345
5.7 Analyzing results...................................................................................................... 349
5.7.1 Configuring traces....................................................................................................... 349
5.7.2 Using markers............................................................................................................. 355
5.7.2.1 General marker settings..............................................................................................355
Contents
5.7.2.2 Configuring individual markers....................................................................................356
5.7.2.3 Positioning markers.....................................................................................................362
5.7.3 Configuring numerical result displays......................................................................... 366
5.7.4 Configuring the statistics table.................................................................................... 370
5.7.5 Configuring result display characteristics....................................................................371
5.7.6 Scaling the diagram axes............................................................................................376
5.7.7 Managing measurement data..................................................................................... 381
5.8 Deprecated remote commands for amplifier measurements............................... 382
5.9 Programming example R&S FSW-K18M................................................................. 383
List of Commands (Amplifier)...........................................................385
Index....................................................................................................407
7User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Contents
8User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
1 Welcome to the amplifier measurement
Welcome to the amplifier measurement application
Starting the application
application
The R&S FSW-K18 is a firmware application that adds functionality to measure the efficiency of amplifiers with the R&S FSW signal analyzer. You extend the amplifier application with the R&S FSW-K18D, which adds direct DPD functionality.
This user manual contains a description of the functionality that the application provides, including remote control operation.
Functions that are not discussed in this manual are the same as in the base unit and
are described in the R&S FSW user manual. The latest versions of the manuals are
available for download at the product homepage.
http://www.rohde-schwarz.com/product/FSW.html.
Installation
Find detailed installing instructions in the getting started or the release notes of the
R&S FSW.
● Starting the application..............................................................................................9
● Understanding the display information....................................................................10
1.1 Starting the application
The amplifier measurement application adds a new type of measurement to the
R&S FSW.
To activate the amplifier application
1. Press the [MODE] key on the front panel of the R&S FSW.
A dialog box opens that contains all operating modes and applications currently
available on your R&S FSW.
2. Select the "Amplifier" item.
The R&S FSW opens a new measurement channel for the amplifier application.
All settings specific to amplifier measurements are in their default state.
9User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
1.2 Understanding the display information
Welcome to the amplifier measurement application
Understanding the display information
The following figure shows the display as it looks for amplifier measurements. All different information areas are labeled. They are explained in more detail in the following
sections.
1 2 3 5 6
Figure 1-1: Screen layout of the amplifier measurement application
4
1 = Toolbar
2 = Channel bar
3 = Diagram header
4 = Result display
5 = Status bar
6 = Softkey bar
For a description of the elements not described below, refer to the getting started of the
R&S FSW.
Channel bar information
The channel bar contains information about the current measurement setup, progress
and results.
Figure 1-2: Channel bar of the amplifier application
10User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Welcome to the amplifier measurement application
Understanding the display information
Ref Level Current reference level of the analyzer.
Att Current attenuation of the analyzer.
Freq Frequency the signal is transmitted on.
Meas Time Length of the signal capture.
Meas BW Bandwidth with which the signal is recorded.
TTF Time difference between the trigger event and the first sample of the reference
signal (= beginning of a frame).
SRate Sample rate with which the signal is recorded.
SGL Indicates that single sweep mode is active.
Count The current signal count for measurement tasks that involve a specific number
of subsequent sweeps (for example the parameter sweep).
X Axis X-axis value that is currently measured.
Y Axis Y-axis value that is currently measured.
Window title bar information
For each diagram, the header provides the following information:
1
Figure 1-3: Window title bar information of the amplifier application
1 = Window number
2 = Window type
3 = Trace color and number
4 = Trace mode
Blue color = Window is selected
2 3 4
Status bar information
Global instrument settings, the instrument status and any irregularities are indicated in
the status bar beneath the diagram. Furthermore, the progress of the current operation
is displayed in the status bar.
11User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
2 Measurements and result displays
Measurements and result displays
Note that you can use the R&S FSW-K18 with the sequencer that is available with the
R&S FSW. The functionality is the same as in the spectrum application. Refer to the
R&S FSW user manual for more information.
Adjacent Channel Leakage Error (ACLR).....................................................................12
AM/AM.......................................................................................................................... 13
AM/PM.......................................................................................................................... 14
Channel Response Magnitude / Channel Response Phase / Group Delay (R&S FSW-
K18F)............................................................................................................................ 15
DDPD Results (R&S FSW-K18D)................................................................................. 17
EVM vs Power...............................................................................................................18
Error Vector Spectrum...................................................................................................19
Gain Compression........................................................................................................ 19
Gain Deviation vs Time.................................................................................................21
Vcc vs Icc......................................................................................................................21
Magnitude Capture........................................................................................................22
Memory DPD Coefficients.............................................................................................22
PAE vs Input Power / PAE vs Output Power.................................................................23
PAE vs Time..................................................................................................................23
Parameter Sweep......................................................................................................... 24
└ Parameter Sweep: Diagram............................................................................24
└ Parameter Sweep: Table.................................................................................25
Phase Deviation vs Time...............................................................................................26
Power vs Time...............................................................................................................26
Raw EVM...................................................................................................................... 27
Numeric Result Summary............................................................................................. 28
└ Results to check modulation accuracy............................................................29
└ Results to check power characteristics...........................................................32
└ Results to check the power supply characteristics of the amplifier.................34
Spectrum FFT............................................................................................................... 35
Time Domain.................................................................................................................35
└ Scale of the x-axis (display settings for the time domain)...............................36
└ Scale of the y-axis (display settings for the time domain)...............................37
Statistics Table.............................................................................................................. 37
Vcc vs Power / Icc vs Power.........................................................................................38
Adjacent Channel Leakage Error (ACLR)
The "ACLR" result display shows the power characteristics of the transmission (Tx)
channel and its neighboring channel(s).
The ACLR measurement in the R&S FSW-K18 is a measurement based on I/Q data.
Thus, its results are calculated by the same I/Q data as the rest of the results (like the
EVM). Note that the supported channel bandwidth is limited by the I/Q bandwidth of the
analyzer you are using.
The results are provided in numerical form in a table. The table is made up out of two
parts, one part containing the characteristics of the Tx channel, the other containing
those of the neighboring channels.
12User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Measurements and result displays
The table contains the following information.
●
Channel
Shows the type of channel.
●
Bandwidth
Shows the channel's bandwidth.
●
Offset (neighboring channels only)
Shows the frequency offset between the center frequency of the adjacent (or alternate) channel and the center frequency of the transmission channel.
●
Power
Shows the power of the transmission channel, or the power of the upper / lower
neighboring channel.
The result is calculated over the complete capture buffer, not just the evaluation
range.
●
Balanced
Shows the difference between the lower and upper adjacent channel power
("Lower Channel" - "Upper Channel").
For more information on configuring the ACP measurement, see Chapter 3.16, "Con-
figuring adjacent channel leakage error (ACLR) measurements", on page 116.
Remote command:
Selection: LAY:ADD? '1',LEFT,ACP
Result query: CALCulate<n>:MARKer<m>:FUNCtion:POWer:RESult?
on page 339
AM/AM
The "AM/AM" result display shows nonlinear effects of the DUT. It shows the amplitude
at the DUT input against the amplitude at the DUT output.
The ideal "AM/AM" curve would be a straight line at 45°. However, nonlinear effects
result in a measurement curve that does not follow the ideal curve. When you drive the
amplifier into saturation, the curve typically flattens at high input levels.
The width of the "AM/AM" trace is an indicator of memory effects: the larger the width
of the trace, the more memory effects occur. The "AM/AM" Curve Width is shown in the
numerical Result Summary.
Both axes show the power of the signal in dBm.
You can analyze the "AM/AM" characteristics of the measured signal and the modeled
signal.
●
Measured signal
13User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Measurements and result displays
Shows the "AM/AM" characteristics of the DUT.
The software uses the reference signal in combination with the synchronized measurement signal to calculate a software model that describes the characteristics of
the device under test.
The measured signal is represented by a colored cloud of values. The cloud is
based on the recorded samples. If samples have the same values (and would thus
be superimposed), colors represent the statistical frequency with which a certain
input / output level combination occurs. Blue pixels represent low statistical frequencies, red pixels high statistical frequencies. A color map is provided within the
result display.
●
Modeled signal
Shows the "AM/AM" characteristics of the model that has been calculated. The
modeled signal is calculated by applying the DUT model to the reference signal.
When the model matches the characteristics of the DUT, the characteristics of the
model signal are the same as those of the measured signal (minus noise).
The modeled signal is represented by a line trace.
When system modeling has been turned off, this trace is not displayed.
All traces include the digital predistortion, when you have turned on that feature.
Remote command:
Selection: LAY:ADD? '1',LEFT,AMAM
Result query: TRACe<n>[:DATA]? on page 163
AM/PM
The "AM/PM" result display shows nonlinear effects of the DUT. It shows the phase difference between DUT input and output for each sample of the synchronized measurement signal.
The ideal "AM/PM" curve would be a straight line at 0°. However, nonlinear effects
result in a measurement curve that does not follow the ideal curve. Typically, the curve
drifts from a zero phase shift, especially at high power levels when you drive the amplifier into saturation.
The width of the "AM/PM" trace is an indicator of memory effects: the larger the width
of the trace, the more memory effects occur. The "AM/PM" curve width is shown in the
numerical Result Summary.
The x-axis shows the levels of all samples of the reference signal (input power) or the
measurement signal (output power) in dBm. You can select the reference of the x-axis
(input or output power) in the "Result Configuration" dialog box.
14User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Measurements and result displays
The y-axis shows the phase of the signal for the corresponding power level. The unit is
either rad or degree, depending on your phase unit selection in the "Result Configuration" dialog box.
You can analyze the "AM/PM" characteristics of the real DUT or of the modeled DUT.
●
Measured signal
Shows the "AM/PM" characteristics of the DUT.
The software uses the reference signal together with the synchronized measurement signal to calculate a software model that describes the characteristics of the
device under test.
The measured signal is represented by a colored cloud of values. The cloud is
based on the recorded samples. If samples have the same values (and would thus
be superimposed), colors represent the statistical frequency with which a certain
input / output level combination occurs. A color map is provided within the result
display.
●
Modeled signal
Shows the "AM/PM" characteristics of the model that has been calculated. The
modeled signal is calculated by applying the DUT model to the reference signal.
When the model matches the characteristics of the DUT, the characteristics of the
modeled signal are the same as those of the measured signal (minus noise).
The modeled signal is represented by a line trace.
When system modeling has been turned off, this trace is not displayed.
All traces include the digital predistortion, when you have turned on that feature.
Remote command:
Selection: LAY:ADD? '1',LEFT,AMPM
Result query: TRACe<n>[:DATA]? on page 163
Channel Response Magnitude / Channel Response Phase / Group Delay
(R&S FSW-K18F)
The channel response and group delay result displays show the deviation of the measured signal compared to the reference signal within the measured channel. The result
displays contain a single trace.
Outside of the occupied bandwidth, the reference signal values usually lie below the
measured noise floor. This can result in large peaks on the trace in these areas (usually to the left and right of the channel). Note that because of the automatic y-axis scal-
ing, the trace can appear in parts as a straight horizontal line. In that case, adjust the
scale of the y-axis manually.
15User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Measurements and result displays
Channel Response Magnitude
The "Channel Response Magnitude" result display analyzes the magnitude characteristics of the signal over the measurement bandwidth.
For the "Channel Response Magnitude", the y-axis shows the deviation of the measured magnitude relative to the transmitted signal power of the signal generator in dB.
The x-axis shows the frequency over which the signal was measured.
Channel Response Phase
The "Channel Response Phase" result display analyzes the phase characteristics of
the signal over the measurement bandwidth.
For the "Channel Response Phase", the y-axis shows the phase deviation relative to
the reference signal. The unit depends on your selection. The x-axis shows the frequency over which the signal was measured.
Group Delay
16User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Measurements and result displays
The "Group Delay" result display analyzes the relative group delay of the signal over
the measurement bandwidth.
For the "Group Delay", the y-axis shows the measured time delay relative to the reference signal in seconds. The x-axis shows the frequency over which the signal was
measured.
Remote command:
Selection (magnitude): LAY:ADD? '1',LEFT,MRES
Selection (phase): LAY:ADD? '1',LEFT,PRES
Selection (group delay): LAY:ADD? '1',LEFT,GDEL
Result query: TRACe<n>[:DATA]? on page 163
DDPD Results (R&S FSW-K18D)
The "DDPD Results" result display shows a selectable result (such as EVM or ACLR)
over all iterations of the direct DPD. This allows verification of the direct DPD's convergence as well as picking the ideal iteration step for further processing (e.g. in
R&S FSW-K18M). It is only available with application R&S FSW-K18D installed.
The display must be placed on screen before starting the direct DPD. The result type is
configurable in the "Result Configuration" dialog box.
17User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Measurements and result displays
Remote command:
Selection: LAY:ADD? '1',LEFT,DDPD
Configure result type: CONFigure:DDPD:WINDow<n>:RESult on page 325
Result query: TRACe<n>[:DATA]? on page 163
EVM vs Power
The "EVM vs Power" result display shows the EVM against the measured power values.
The ideal EVM vs power curve would be a straight line at 0 %. However, among other
effects such as noise, nonlinear effects of the DUT cause an increase of the EVM.
Nonlinear effects usually occur on high power levels that drive the power amplifier into
saturation.
The x-axis shows the levels of all samples of the reference signal (input power) or the
measurement signal (output power) in dBm. You can select the reference of the x-axis
(input or output power) in the "Result Configuration" dialog box.
The y-axis shows the EVM of the signal for the corresponding power level in %.
All traces include the digital predistortion, when you have turned on that feature.
18User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Measurements and result displays
Remote command:
Selection: LAY:ADD? '1',LEFT,AMEV
Result query: TRACe<n>[:DATA]? on page 163
Error Vector Spectrum
The "Error Vector Spectrum" result display shows the error vector (EV) signal in the
spectrum around the center frequency.
The EV is a measure of the modulation accuracy. It compares two signals and shows
the distance of the measured constellation points and the ideal constellation points.
The unit is dB.
You can compare the measured signal against the reference signal and against the
modeled signal.
●
Measured signal against reference signal
Trace 1 compares measured signal and the reference signal.
To get useful results, the calculated linear gain is compensated to match both signals.
Depending on the DUT, noise and nonlinear effects may have been added to the
measurement signal. These effects are visualized by this trace.
●
Measured signal against modeled signal
Trace 2 compares measured signal and the modeled signal.
The EVM between the measured and modeled signal indicates the quality of the
DUT modeling. If the model matches the DUT behavior, the modeling error is zero
(or is merely influenced by noise).
This result display shows changes in the model and its parameters and thus allows
you to optimize the modeling.
When system modeling has been turned off, this trace is not displayed.
Remote command:
Selection: LAY:ADD? '1',LEFT,SEVM
Result query: TRACe<n>[:DATA]? on page 163
Gain Compression
The "Gain Compression" result display shows the gain and error effects of the DUT
against the DUT input or output power.
The gain is the ratio of the input and output power of the DUT.
19User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Measurements and result displays
The x-axis shows the levels of all samples of the reference signal (input power) or the
measurement signal (output power) in dBm. You can select the reference of the x-axis
(input or output power) in the "Result Configuration" dialog box.
The y-axis shows the gain in dB.
The ideal gain compression curve would be a straight horizontal line. However, nonlin-
ear effects result in a measurement curve that does not follow the ideal curve. In addition, the curve widens at very low input levels due to noise influence.
The width of the gain compression trace is an indicator of memory effects: the larger
the width of the trace, the more memory effects occur.
You can analyze the gain characteristics of the measured signal and the modeled signal.
●
Measured signal
Shows the gain characteristics of the DUT.
The software uses the reference signal in combination with the synchronized measurement signal to calculate a software model that describes the characteristics of
the device under test.
The measured gain is represented by a colored cloud of values. The cloud is
based on the recorded samples. If samples have the same values (and would thus
be superimposed), colors represent the statistical frequency with which a certain
input / output level combination occurs. Blue pixels represent low statistical frequencies, red pixels high statistical frequencies. A color map is provided within the
result display.
●
Modeled signal
Shows the gain characteristics of the model that has been calculated. The modeled
signal is calculated by applying the DUT model to the reference signal.
When the model matches the characteristics of the DUT, the characteristics of the
model signal are the same as those of the measured signal (minus noise).
The modeled signal is represented by a line trace.
When system modeling has been turned off, this trace is not displayed.
In addition, one or more horizontal lines can appear in the result display.
●
One line to indicate each compression point (1 dB, 2 dB and 3 dB).
●
One line to indicate the reference point (0 dB compression) that the compression
points refer to.
Remote command:
Selection: LAY:ADD? '1',LEFT,GC
Result query: TRACe<n>[:DATA]? on page 163
20User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Measurements and result displays
Gain Deviation vs Time
The "Gain Deviation vs Time" result display shows the deviation of each measured signal sample from the average gain of the measured signal.
The x-axis shows the time in seconds. The y-axis shows the gain deviation in dB.
The displayed results are based on the synchronized measurement data (represented
by the green bar in the capture buffer).
Note that the result query and trace export only work for unencrypted reference signal
waveform files.
Remote command:
Selection: LAY:ADD? '1',LEFT,GDVT
Result query: TRACe<n>[:DATA]? on page 163
Vcc vs Icc
Note: This result display requires you to turn on the baseband input.
The "Vcc vs Icc" result display shows the supply voltage that has been measured on
baseband input Q against the current consumption that has been measured on base-
band input I (using a shunt resistor or current probe).
The x-axis shows the voltage (V). The y-axis shows the current (A).
The resulting trace is usually represented by a cloud of values. The cloud is based on
the recorded samples. If samples have the same values (and would thus be superimposed), colors represent the statistical frequency with which a certain level / gain combination occurs. Blue pixels represent low statistical frequencies, red pixels high statistical frequencies. A color map is provided within the result display.
21User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Measurements and result displays
Remote command:
Selection: LAY:ADD? '1',LEFT,VICC
Result query: TRACe<n>[:DATA]? on page 163
Magnitude Capture
(RF, I and Q)
Note: The magnitude capture I and Q results displays require you to turn on the base-
band input.
The "Magnitude Capture" result display contains the raw data that has been recorded
and thus represents the characteristics of the DUT.
It is available for the data recorded on the RF input and both baseband inputs (I and Q
channels). (Note that the I and Q channel capture buffers are only available when par-
allel baseband capture is active.)
The capture buffer shows the signal level over time. The unit is either dBm (RF capture), V or A (baseband capture).
For a baseband capture, all multipliers and offsets are already included in the results.
The raw data is source for all further evaluations. You can also use the data in the cap-
ture buffer to identify the causes for possible unexpected results.
When you synchronize the reference signal and the measured signal, the synchronized
area is indicated by a horizontal green bar on the bottom of the diagram.
The current reference level is indicated by a red horizontal line.
The green bar at the bottom shows the current frame. In I/Q averaging mode, the aver-
age value is shown. In trace statistics mode, multiple values are possible. The currently
selected value is symbolized by a blue bar.
Remote command:
Selection (RF): LAY:ADD? '1',LEFT,RFM
Selection (I): LAY:ADD? '1',LEFT,IMAG
Selection (Q): LAY:ADD? '1',LEFT,QMAG
Result query: TRACe<n>[:DATA]? on page 163
Memory DPD Coefficients
The "Memory DPD Coefficients" result table shows basically complex filter coefficients
for each polynomial degree. The two lines "1(Real)" and "1(Imag)" describe the complex impulse response for polynomial degree 1 (linear) of a filter from left to right. It is
only available with application R&S FSW-K18M installed.
22User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Measurements and result displays
Remote command:
Selection: LAY:ADD? '1',LEFT,MDPD
Result query: FETCh:MDPD:COEFficients? on page 335
PAE vs Input Power / PAE vs Output Power
Note: This result display requires you to turn on the baseband input.
The "PAE vs Input Power" / "PAE vs Output Power" result displays show the power
added efficiency (PAE) against the input or output power. It helps you to find the input
or output levels at which the DUT works most efficiently.
The x-axis shows the levels of all samples of the reference signal (input power) or the
measurement signal (output power) in dBm.
The y-axis shows the efficiency in %, based on the following formula:
PAE = (RF output power - RF input power) / DC power
The measured signal is represented by a colored cloud of values. The cloud is based
on the recorded samples. If samples have the same values (and would thus be superimposed), colors represent the statistical frequency with which a certain input / output
level combination occurs. Blue pixels represent low statistical frequencies, red pixels
high statistical frequencies. A color map is provided within the result display.
Remote command:
Selection: LAY:ADD? '1',LEFT,PAEI
Result query: TRACe<n>[:DATA]? on page 163
PAE vs Time
Note: This result display requires you to turn on the baseband input.
23User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Measurements and result displays
The "PAE vs Time" result display shows the power added efficiency against time.
The x-axis represents the time in seconds. The y-axis shows the efficiency in %, based
on the following formula:
PAE = (RF output power - RF input power) / DC power
Remote command:
Selection: LAY:ADD? '1',LEFT,PAET
Result query: TRACe<n>[:DATA]? on page 163
Parameter Sweep
The "Parameter Sweep" result display is a result display that shows a result of the DUT
(for example the EVM) against two (custom) measurement parameters. The results of
this measurement are displayed in graphical and numerical form.
The parameter sweep is a good way, for example, to find the location of the ideal delay
time of the RF signal and the envelope signal if you are measuring an amplifier that
supports envelope tracking. You can also use the parameter sweep to determine the
characteristics and behavior of an amplifier over different frequencies and levels.
For more information about supported parameters and how to set them up see "Select-
ing the data to be evaluated during the parameter sweep" on page 121.
Parameter Sweep: Diagram ← Parameter Sweep
The parameter sweep diagram is a graphical representation of the parameter sweep
results. The results are either represented as a two-dimensional trace or as a threedimensional trace, depending on whether you are performing a parameter sweep with
one or two parameters.
In a two-dimensional diagram, the y-axis always shows the result. The displayed result
depends on the result type you have selected. The information displayed on the x-axis
depends on the parameter you have selected for evaluation (for example the EVM over
a given frequency range). Values between measurement point are interpolated. Basically, you can interpret the two-dimensional diagram as follows (example): "at a frequency of x Hz, the EVM has a value of y."
24User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Measurements and result displays
In a three-dimensional diagram, the z-axis always shows the result. The information on
the other two axes is arbitrary and depends on the parameters you have selected for
evaluation. For a better readability, the result values in the three-dimensional diagram
are represented by a colored trace: low values have a blue color, while high values
have a red color. Values between measurement point are interpolated. Basically, you
can interpret the three-dimensional diagram as follows (example): "at a frequency of
x Hz and a level of y, the EVM has a value of z."
Parameter Sweep: Table ← Parameter Sweep
The parameter sweep table shows the minimum and maximum results for all available
result types in numerical form. For each result type, the location where the minimum
and maximum result has occurred is displayed.
Example:
A minimum EVM of 0.244 % and a maximum EVM of 0.246 % has been measured
(first and second row). The minimum EVM has been measured at a frequency of
30 MHz and an output power of 0 dBm. The maximum EVM has been measured at a
frequency of 10 MHz and an output power of 0 dBm.
The following result types are evaluated in the parameter sweep.
Result Description
EVM Error vector magnitude between synchronized reference and mea-
surement signal.
ACLR Power of the transmission channel.
ACLR Adj Upper / Lower Power of the adjacent channels (upper and lower).
ACLR Balanced (Adj, Alt1 and
Alt2)
RMS Power RMS signal power at the DUT output.
Gain Gain of the DUT.
Crest Factor Out Crest factor of the signal at the DUT output. The crest factor is the
Curve Width ("AM/AM", "AM/PM") Spread of the samples in the "AM/AM" (or "AM/PM") result display
Power Out Signal power at the DUT output.
Difference between the lower and upper adjacent channel power
ratio of the RMS and peak power.
compared to the ideal "AM/AM" (or "AM/PM") curve.
25User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Measurements and result displays
Result Description
Compression Point (1 dB / 2 dB /
3 dB)
Bal ACLR Magnitude Shows the difference between the lower and upper adjacent channel
Voltage (V_cc) Amplifier supply voltage.
Current (I_cc) Amplifier current consumption.
Power (V_cc * I_cc) Amplifier DC power.
PAE Power added efficiency.
Input power where the gain deviates by 1 dB, 2 dB or 3 dB from a reference gain (see "Configuring compression point calculation"
on page 116).
power.
Remote command:
Chapter 5.5.3.3, "Retrieving results of the parameter sweep table", on page 180
Phase Deviation vs Time
The "Phase Deviation vs Time" result display shows the phase deviation of the measured signal compared to the reference signal over time.
The x-axis shows the time in seconds. The y-axis shows the phase deviation in
degree.
The displayed results are based on the synchronized measurement data (represented
by the green bar in the capture buffer).
Note that the result query and trace export only work for unencrypted reference signal
waveform files.
Remote command:
Selection: LAY:ADD? '1',LEFT,PDVT
Result query: TRACe<n>[:DATA]? on page 163
Power vs Time
Note: This result display requires you to turn on the baseband input.
The "Power vs Time" result display shows the supply power of the power amplifier
against time.
The results are calculated by multiplying the supply voltage with the supply current
which are recorded at the baseband inputs of the R&S FSW.
The unit of the results is W.
26User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Measurements and result displays
For valid results, make sure that you have configured the measurement correctly
regarding the equipment you are using.
Remote command:
Selection: LAY:ADD? '1',LEFT,PVT
Result query: TRACe<n>[:DATA]? on page 163
Raw EVM
The "Raw EVM" result display shows the error vector magnitude of the signal over
time.
The EVM is a measure of the modulation accuracy. It compares two signals and shows
the distance of the measured constellation points and the ideal constellation points.
You can compare the measured signal against the reference signal and against the
modeled signal.
●
Measured signal against reference signal
Trace 1 compares the measured signal and the reference signal.
To get useful results, the calculated linear gain is compensated to match both signals.
Depending on the DUT, noise and nonlinear effects may have been added to the
measurement signal. These effects are visualized by this trace.
●
Measured signal against modeled signal
Trace 2 compares the measured signal and the modeled signal.
The EVM between the measured and modeled signal indicates the quality of the
DUT modeling. If the model matches the DUT behavior, the modeling error is zero
(or is merely influenced by noise).
This result display shows changes in the model and its parameters and thus allows
you to optimize the modeling.
When system modeling has been turned off, this trace is not displayed.
Note that the raw EVM is calculated for each sample that has been recorded. Thus, the
raw EVM can differ from EVM values that are calculated according to a specific mobile
communication standard that apply special rules to calculate the EVM, for example
LTE.
27User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Measurements and result displays
Remote command:
Selection: LAY:ADD? '1',LEFT,REVM
Result query: TRACe<n>[:DATA]? on page 163
Numeric Result Summary
The "Result Summary" shows various measurement results in numerical form, combined in one table.
The table is split in two parts (three parts when you use the baseband input).
●
The first part shows the modulation accuracy
●
The second part shows the power characteristics of the RF signal
●
The third part shows the power supply characteristics of the amplifier
For each result type, several values are displayed.
●
Current
Value measured during the last sweep.
For measurements that evaluate each captured sample, this value represents the
average value over all samples captured in the last sweep.
●
Min
For measurements that evaluate each captured sample, this value represents the
sample with lowest value captured in the last sweep.
●
Max
For measurements that evaluate each captured sample, this value represents the
sample with the highest value captured in the last sweep.
28User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Measurements and result displays
●
Unit
Unit of the result.
Results that evaluate each captured sample
●
"Raw EVM" and Raw Model EVM
●
Power In and Power Out
●
All baseband results, except the Average PAE
Note: When synchronization has failed or has been turned off, some results may be
unavailable.
Remote command:
Selecting the result display: LAY:ADD? '1',LEFT,RTAB
Querying results: see Chapter 5.5.3, "Retrieving numeric results", on page 164
Results to check modulation accuracy ← Numeric Result Summary
Raw EVM Error vector magnitude between synchronized reference and measured sig-
nal.
FETCh:MACCuracy:REVM:CURRent[:RESult]? on page 169
Raw Model EVM Error vector magnitude between synchronized measured and model signal.
FETCh:MACCuracy:RMEV:CURRent[:RESult]? on page 170
Frequency Error Difference of the RF frequency of the reference signal compared to the mea-
sured signal.
Note that a frequency error is not available if the frequency error estimation is
switched off. See also Chapter 3.10, "Estimating and compensating signal
errors", on page 96.
FETCh:MACCuracy:FERRor:CURRent[:RESult]? on page 167
Sample Rate Error Sample rate difference between reference and measured signal.
Note that a sample rate error is not available if the sample rate error estimation is switched off. See also Chapter 3.10, "Estimating and compensating sig-
nal errors", on page 96.
FETCh:MACCuracy:SRERror:CURRent[:RESult]? on page 170
Magnitude Error Difference in magnitude between the reference signal and the measured sig-
nal.
FETCh:MACCuracy:MERRor:CURRent[:RESult]? on page 168
29User Manual 1176.9893.02 ─ 22
R&S®FSW-K18
Measurements and result displays
Phase Error Phase difference between reference and measured signal.
FETCh:MACCuracy:PERRor:CURRent[:RESult]? on page 168
Quadrature Error Phase deviation of the 90° phase difference between the real (I) and imagi-
nary (Q) part of the signal.
Within an ideal transmitter, the I and Q signal parts are mixed with an angle of
90° by the I/Q output mixer. Due to hardware imperfections, the signal delay of
I and Q can be different and thus lead to an angle non-equal to 90°.
Note that quadrature rate error is not available if the I/Q Imbalance estimation
is switched off. See also Chapter 3.10, "Estimating and compensating signal
errors", on page 96.
FETCh:MACCuracy:QERRor:CURRent[:RESult]? on page 169
30User Manual 1176.9893.02 ─ 22
Loading...