Rohde&Schwarz R&S®VSE-K18 Amplifier Measurements User Manual
R&S®VSE-K18
Power Amplifier and Envelope
Tracking Measurements
User Manual
(;ÝP×2)
1179327302
Version 03
This manual applies to the following software, version 2.20 and later:
●
R&S®VSE Enterprise Edition base software (1345.1105.06)
●
R&S®VSE Basic Edition base software (1345.1011.06)
The following firmware options are described:
●
R&S®VSE-K18 (1345.1434.02)
●
R&S®VSE-K18D (1345.1440.02)
●
R&S®VSE-K18F (1345.1457.02)
●
R&S®VSE-K18M (1345.1492.02)
●
R&S®VSE-KT18 (1345.2060.02)
●
R&S®VSE-KT18D (1345.2053.02)
●
R&S®VSE-KT18F (1345.2047.02)
●
R&S®VSE-KT18M (1345.2030.02)
© 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.
1179.3273.02 | Version 03 | R&S®VSE-K18
Throughout this manual, products from Rohde & Schwarz are indicated without the ® symbol , e.g. R&S®VSE is indicated as
R&S VSE.
R&S®VSE-K18
1.1 Starting the application................................................................................................ 9
1.2 Understanding the display information.................................................................... 10
3.1 Configuration overview.............................................................................................. 33
3.2 Designing a reference signal..................................................................................... 35
3.3 Configuring inputs and outputs.................................................................................45
3.3.1 Input source settings..................................................................................................... 45
3.3.1.1 Radio frequency input................................................................................................... 46
Contents
Contents
1 Welcome to the amplifier measurement application.......................... 9
2 Measurements and result displays.................................................... 12
3 Configuration........................................................................................33
3.3.1.2 I/Q file input................................................................................................................... 50
3.3.2 Configuring the frequency............................................................................................. 52
3.3.3 Defining level characteristics.........................................................................................53
3.3.4 Power sensors.............................................................................................................. 56
3.3.5 Configuring outputs....................................................................................................... 61
3.3.6 Controlling a signal generator....................................................................................... 61
3.3.7 Reference: I/Q file input................................................................................................ 66
3.3.7.1 Basics on input from I/Q data files................................................................................ 66
3.3.7.2 I/Q data file format (iq-tar)............................................................................................. 67
I/Q parameter XML file specification............................................................................. 69
I/Q data binary file......................................................................................................... 78
3.4 Triggering measurements.......................................................................................... 80
3.5 Configuring the data capture..................................................................................... 81
3.6 Sweep configuration...................................................................................................84
3.7 Synchronizing measurement data.............................................................................86
3.8 Evaluating measurement data................................................................................... 88
3.9 Estimating and compensating signal errors............................................................ 90
3.10 Equalizer...................................................................................................................... 91
3.11 Applying system models............................................................................................92
3.12 Applying digital predistortion.................................................................................... 95
3.12.1 Polynomial DPD............................................................................................................ 96
3User Manual 1179.3273.02 ─ 03
R&S®VSE-K18
3.12.2 Direct DPD (R&S VSE-K18D)....................................................................................... 98
3.12.3 Memory polynomial DPD (R&S VSE-K18M)...............................................................103
3.12.4 Hammerstein model (R&S VSE-K18M)...................................................................... 105
3.13 Detailed MSE............................................................................................................. 108
3.14 Configuring power measurements..........................................................................109
3.15 Configuring adjacent channel leakage error (ACLR) measurements.................. 110
3.16 Configuring the parameter sweep........................................................................... 113
3.17 Configuring power servoing.................................................................................... 117
4.1 Configuring traces.................................................................................................... 119
4.1.1 Selecting the trace information....................................................................................119
4.1.2 Exporting traces.......................................................................................................... 122
Contents
4 Analysis...............................................................................................119
4.1.3 Detector settings......................................................................................................... 123
4.2 Using markers........................................................................................................... 124
4.2.1 Configuring markers....................................................................................................124
4.2.2 Configuring individual markers....................................................................................125
4.2.3 Positioning markers.....................................................................................................127
4.3 Customizing numerical result tables...................................................................... 128
4.4 Configuring result display characteristics............................................................. 130
4.5 Scaling the X-Axis.....................................................................................................132
4.6 Scaling the Y-Axis.....................................................................................................134
5 Remote control commands for amplifier measurements...............136
5.1 Introduction............................................................................................................... 136
5.1.1 Conventions used in descriptions............................................................................... 137
5.1.2 Long and short form.................................................................................................... 137
5.1.3 Numeric suffixes..........................................................................................................138
5.1.4 Optional keywords.......................................................................................................138
5.1.5 Alternative keywords................................................................................................... 138
5.1.6 SCPI parameters.........................................................................................................139
5.1.6.1 Numeric values........................................................................................................... 139
5.1.6.2 Boolean....................................................................................................................... 140
5.1.6.3 Character data............................................................................................................ 140
5.1.6.4 Character strings.........................................................................................................141
4User Manual 1179.3273.02 ─ 03
R&S®VSE-K18
5.1.6.5 Block data................................................................................................................... 141
5.2 Common suffixes...................................................................................................... 141
5.3 Selecting the application..........................................................................................141
5.4 Performing amplifier measurements.......................................................................142
5.4.1 Activating Amplifier measurements.............................................................................142
5.4.2 Retrieving graphical measurement results..................................................................142
5.4.3 Retrieving numeric results...........................................................................................145
5.4.3.1 Retrieving general numeric results..............................................................................145
5.4.3.2 Retrieving results of the result summary.....................................................................145
Contents
Retrieving all results....................................................................................................145
Retrieving the modulation accuracy............................................................................ 146
Retrieving power results..............................................................................................150
Retrieving baseband characteristics........................................................................... 157
5.4.3.3 Retrieving results of the parameter sweep table.........................................................160
5.4.3.4 Retrieving results of the statistics table.......................................................................174
Amplitude droop.......................................................................................................... 175
AM/AM curve width..................................................................................................... 175
AM/PM curve width..................................................................................................... 176
Average PAE...............................................................................................................177
Power (Vcc*Icc)...........................................................................................................180
Crest factor input.........................................................................................................183
Crest factor out............................................................................................................184
Frequency error...........................................................................................................185
Gain.............................................................................................................................186
Gain imbalance........................................................................................................... 187
Current (Icc)................................................................................................................ 188
I/Q imbalance.............................................................................................................. 191
I/Q offset......................................................................................................................192
Baseband i input voltage.............................................................................................193
Magnitude error...........................................................................................................196
P1DB input.................................................................................................................. 197
P1DB output................................................................................................................198
P2DB input.................................................................................................................. 199
5User Manual 1179.3273.02 ─ 03
R&S®VSE-K18
Contents
P2DB output................................................................................................................200
P3DB input.................................................................................................................. 201
P3DB output................................................................................................................202
Average power consumption.......................................................................................203
PC based average PAE...............................................................................................204
Phase error................................................................................................................. 205
Power input................................................................................................................. 206
Power output............................................................................................................... 209
Quadrature error......................................................................................................... 212
Baseband q input voltage............................................................................................213
Raw EVM.................................................................................................................... 216
Raw model EVM......................................................................................................... 219
Sample rate error........................................................................................................ 222
Voltage (Vcc)...............................................................................................................223
5.4.4 Retrieving I/Q data...................................................................................................... 226
5.5 Configuring amplifier measurements..................................................................... 227
5.5.1 Designing a reference signal.......................................................................................228
5.5.2 Power sensor measurements..................................................................................... 242
5.5.2.1 Configuring power sensor measurements.................................................................. 242
5.5.2.2 Triggering with power sensors.................................................................................... 251
5.5.3 Configuring data input................................................................................................. 254
5.5.3.1 RF input.......................................................................................................................254
5.5.3.2 Remote commands for external frontend control........................................................ 265
Commands for initial configuration..............................................................................266
Commands for alignment............................................................................................ 272
5.5.4 Configuring the frequency........................................................................................... 275
5.5.5 Defining level characteristics.......................................................................................276
5.5.6 Controlling a signal generator..................................................................................... 282
5.5.7 Configuring the data capture.......................................................................................291
5.5.8 Sweep configuration....................................................................................................296
5.5.9 Synchronizing measurement data...............................................................................298
5.5.10 Defining the evaluation range..................................................................................... 301
5.5.11 Estimating and compensating signal errors................................................................ 303
6User Manual 1179.3273.02 ─ 03
R&S®VSE-K18
5.5.11.1 Error estimation and compensation............................................................................ 303
5.5.11.2 Equalizer..................................................................................................................... 306
5.5.12 Applying a system model............................................................................................ 308
5.5.13 Applying digital predistortion........................................................................................311
5.5.14 Detailed MSE.............................................................................................................. 328
5.5.15 Configuring envelope tracking.....................................................................................329
5.5.16 Configuring ACLR measurements.............................................................................. 330
5.5.17 Configuring power measurements.............................................................................. 336
5.5.18 Configuring parameter sweeps................................................................................... 336
5.5.19 Configuring power servoing........................................................................................ 340
5.6 Analyzing results...................................................................................................... 343
5.6.1 Configuring traces....................................................................................................... 343
5.6.2 Using markers............................................................................................................. 349
Contents
5.6.2.1 General marker settings..............................................................................................349
5.6.2.2 Configuring individual markers....................................................................................350
5.6.2.3 Positioning markers.....................................................................................................356
5.6.3 Configuring numerical result displays......................................................................... 360
5.6.4 Configuring the statistics table.................................................................................... 363
5.6.5 Configuring result display characteristics....................................................................364
5.6.6 Scaling the diagram axes............................................................................................368
5.6.7 Managing measurement data..................................................................................... 374
5.7 Deprecated remote commands for amplifier measurements............................... 375
5.8 Programming example R&S VSE-K18M..................................................................376
List of Commands (Amplifier)...........................................................378
Index....................................................................................................400
7User Manual 1179.3273.02 ─ 03
R&S®VSE-K18
Contents
8User Manual 1179.3273.02 ─ 03
R&S®VSE-K18
1 Welcome to the amplifier measurement
Welcome to the amplifier measurement application
Starting the application
application
The R&S VSE-K18 is a firmware application that adds functionality to measure the efficiency of amplifiers with the R&S VSE signal analyzer. You extend the amplifier application with the R&S VSE-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 VSE user manual. The latest versions of the manuals are
available for download at the product homepage.
Installation
Find detailed installing instructions in the getting started or the release notes of the
R&S VSE.
● 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 VSE.
To activate the amplifier application
1.
Select the "Add Channel" function in the Sequence tool window.
A dialog box opens that contains all operating modes and applications currently
available in your R&S VSE.
2. Select the "Amplifier" item.
The R&S VSE opens a new measurement channel for the Amplifier measurement
application.
9User Manual 1179.3273.02 ─ 03
R&S®VSE-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 42 3 56
Figure 1-1: Screen layout of the amplifier measurement application
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 VSE.
Channel bar information
The channel bar contains information about the current measurement setup, progress
and results.
10User Manual 1179.3273.02 ─ 03
R&S®VSE-K18
Welcome to the amplifier measurement application
Understanding the display information
Figure 1-2: Channel bar of the amplifier application
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 1179.3273.02 ─ 03
R&S®VSE-K18
2 Measurements and result displays
Measurements and result displays
Note that you can use the R&S VSE-K18 with the sequencer that is available with the
R&S VSE. The functionality is the same as in the spectrum application. Refer to the
R&S VSE user manual for more information.
Adjacent Channel Leakage Error (ACLR).....................................................................12
AM/AM.......................................................................................................................... 13
AM/PM.......................................................................................................................... 14
DDPD Results (R&S VSE-K18D)..................................................................................15
EVM vs Power...............................................................................................................16
Error Vector Spectrum...................................................................................................17
Gain Compression........................................................................................................ 17
Gain Deviation vs Time.................................................................................................19
Magnitude Capture........................................................................................................19
Memory DPD Coefficients.............................................................................................20
Parameter Sweep......................................................................................................... 20
└ Parameter Sweep: Diagram............................................................................20
└ Parameter Sweep: Table.................................................................................21
Phase Deviation vs Time...............................................................................................22
Raw EVM...................................................................................................................... 22
Numeric Result Summary............................................................................................. 23
└ Results to check modulation accuracy............................................................24
└ Results to check power characteristics...........................................................27
Spectrum FFT............................................................................................................... 29
Time Domain.................................................................................................................30
└ Scale of the x-axis (display settings for the time domain)...............................30
└ Scale of the y-axis (display settings for the time domain)...............................31
Statistics Table.............................................................................................................. 31
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 VSE-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 1179.3273.02 ─ 03
R&S®VSE-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 3.15, "Con-
figuring adjacent channel leakage error (ACLR) measurements", on page 110.
Remote command:
Selection: LAY:ADD? '1',LEFT,ACP
Result query: CALCulate<n>:MARKer<m>:FUNCtion:POWer:RESult?
on page 330
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 1179.3273.02 ─ 03
R&S®VSE-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 143
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 1179.3273.02 ─ 03
R&S®VSE-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 143
DDPD Results (R&S VSE-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 VSE-K18M). It is only available with application R&S VSE-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.
15User Manual 1179.3273.02 ─ 03
R&S®VSE-K18
Measurements and result displays
Remote command:
Selection: LAY:ADD? '1',LEFT,DDPD
Configure result type: CONFigure:DDPD:WINDow<n>:RESult on page 316
Result query: TRACe<n>[:DATA]? on page 143
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.
16User Manual 1179.3273.02 ─ 03
R&S®VSE-K18
Measurements and result displays
Remote command:
Selection: LAY:ADD? '1',LEFT,AMEV
Result query: TRACe<n>[:DATA]? on page 143
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 143
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.
17User Manual 1179.3273.02 ─ 03
R&S®VSE-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 143
18User Manual 1179.3273.02 ─ 03
R&S®VSE-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 143
Magnitude Capture
The "Magnitude Capture" result display contains the raw data that has been recorded
and thus represents the characteristics of the DUT.
The raw data is source for all further evaluations. You can also use the data in the capture 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.
19User Manual 1179.3273.02 ─ 03
R&S®VSE-K18
Measurements and result displays
Remote command:
Selection (RF): LAY:ADD? '1',LEFT,RFM
Result query: TRACe<n>[:DATA]? on page 143
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 VSE-K18M installed.
Remote command:
Selection: LAY:ADD? '1',LEFT,MDPD
Result query: FETCh:MDPD:COEFficients? on page 326
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 115.
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."
20User Manual 1179.3273.02 ─ 03
R&S®VSE-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.
21User Manual 1179.3273.02 ─ 03
R&S®VSE-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
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 110).
power.
Remote command:
Chapter 5.4.3.3, "Retrieving results of the parameter sweep table", on page 160
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 143
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.
22User Manual 1179.3273.02 ─ 03
R&S®VSE-K18
Measurements and result displays
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.
Remote command:
Selection: LAY:ADD? '1',LEFT,REVM
Result query: TRACe<n>[:DATA]? on page 143
Numeric Result Summary
The "Result Summary" shows various measurement results in numerical form, combined in one table.
23User Manual 1179.3273.02 ─ 03
R&S®VSE-K18
Measurements and result displays
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.
●
Unit
Unit of the result.
Results that evaluate each captured sample
●
"Raw EVM" and Raw Model EVM
●
Power In and Power Out
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 5.4.3, "Retrieving numeric results", on page 145
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 149
Raw Model EVM Error vector magnitude between synchronized measured and model signal.
FETCh:MACCuracy:RMEV:CURRent[:RESult]? on page 150
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 3.9, "Estimating and compensating signal
errors", on page 90.
FETCh:MACCuracy:FERRor:CURRent[:RESult]? on page 147
24User Manual 1179.3273.02 ─ 03
R&S®VSE-K18
Measurements and result displays
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 3.9, "Estimating and compensating sig-
nal errors", on page 90.
FETCh:MACCuracy:SRERror:CURRent[:RESult]? on page 150
Magnitude Error Difference in magnitude between the reference signal and the measured sig-
nal.
FETCh:MACCuracy:MERRor:CURRent[:RESult]? on page 148
Phase Error Phase difference between reference and measured signal.
FETCh:MACCuracy:PERRor:CURRent[:RESult]? on page 149
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 3.9, "Estimating and compensating signal
errors", on page 90.
FETCh:MACCuracy:QERRor:CURRent[:RESult]? on page 149
25User Manual 1179.3273.02 ─ 03
R&S®VSE-K18
Measurements and result displays
Gain Imbalance Gain difference between the real (I) and imaginary (Q) part of the signal.
This effect is typically generated by two separate amplifiers with a different
gain in the I and Q path of the analog baseband signal generation.
Note that gain imbalance is not available if the I/Q Imbalance estimation is
switched off. See also Chapter 3.9, "Estimating and compensating signal
errors", on page 90.
FETCh:MACCuracy:GIMBalance:CURRent[:RESult]? on page 147
I/Q Imbalance Combination of Quadrature error and Gain imbalance.
The I/Q imbalance parameter is a representation of the combination of Quadrature error and gain imbalance.
Note that I/Q imbalance is not available if the I/Q imbalance estimation is
switched off. See also Chapter 3.9, "Estimating and compensating signal
errors", on page 90.
FETCh:MACCuracy:IQIMbalance:CURRent[:RESult]? on page 148
26User Manual 1179.3273.02 ─ 03
R&S®VSE-K18
Measurements and result displays
I/Q Offset Shift of the measured signal compared to the ideal I/Q constellation in the I/Q
plane.
Note that I/Q offset is not available if the I/Q Offset estimation is switched off.
See also Chapter 3.9, "Estimating and compensating signal errors",
on page 90.
FETCh:MACCuracy:IQOFfset:CURRent[:RESult]? on page 148
Amplitude Droop Amplitude droop is a measure of the change in magnitude of the signal over
the frame (reference signal) being measured in dB.
Note that amplitude droop is not available if the amplitude droop estimation is
switched off. See also Chapter 3.9, "Estimating and compensating signal
errors", on page 90.
Results to check power characteristics ← Numeric Result Summary
Power In Signal power at the DUT input when reference signal is active. The signal
generator level may change during direct DPD, but this result summary value
will always refer to the reference signal – not the DPD signal.
FETCh:POWer:INPut:CURRent[:RESult]? on page 153
Power In (Sensor) Signal power at the input power sensor.
FETCh:POWer:SENSor:IN:CURRent[:RESult]? on page 156
Power Out Signal power at the DUT output.
Power Out (Sensor) Signal power at the output power sensor.
It is the RMS power of:
●
The currently selected frame, if R&S VSE-K18 has successfully
synchronized.
●
The current capture buffer, if R&S VSE-K18 has not synchronized.
FETCh:POWer:OUTPut:CURRent[:RESult]? on page 153
FETCh:POWer:SENSor:OUT:CURRent[:RESult]? on page 157
27User Manual 1179.3273.02 ─ 03
R&S®VSE-K18
Measurements and result displays
Gain Average gain calculated over all samples of the "Gain Compression" trace.
noise in
output signal
gain
Note that gain is not necessarily equal to the ratio "Power Out" / "Power In".
Gain only describes the ratio of the correlated signal in "Power Out" to "Power
In".
Gain is always referenced to the reference signal power, i.e. when DPD
changes the generator level, the gain is still referenced to the input power of
the reference signal - not the DPD signal.
Example: If the output signal contains the same amount of noise as the correlated signal (e.g. signal is 0 dBm and noise power is also 0 dBm), "Power Out"
will show the sum (3 dBm). However, assuming an input signal power of
-10 dBm, gain will only show 10 dB, not 13 dB.
FETCh:POWer:GAIN:CURRent[:RESult]? on page 152
total output
signal
correlated
output signal
input signal
Crest Factor In Crest factor of the signal at the DUT input. The crest factor is the ratio of the
RMS and peak power.
FETCh:POWer:CFACtor:IN:CURRent[:RESult]? on page 152
Crest Factor Out Crest factor of the signal at the DUT output. The crest factor is the ratio of the
RMS and peak power.
FETCh:POWer:CFACtor:OUT:CURRent[:RESult]? on page 152
AM/AM Curve Width Vertical spread of the samples in the "AM/AM" result display.
The "AM/AM" curve width shows the standard deviation of the output voltage
or the output phase deviation within a +/- 1% range around the mean amplitude in volt.
Output
amplitude
+/- 1%
σ of output
amplitude
in this range
10,5
Input amplitude
linear normalized
FETCh:AMAM:CWIDth:CURRent[:RESult]? on page 151
28User Manual 1179.3273.02 ─ 03
R&S®VSE-K18
Measurements and result displays
AM/PM Curve Width Vertical spread of the samples in the "AM/PM" result display.
The "AM/PM" curve width shows the standard deviation of the output voltage
or the output phase deviation within a +/- 1% range around the mean amplitude in volt.
Output
amplitude
+/- 1%
σ of output
amplitude
in this range
FETCh:AMPM:CWIDth:CURRent[:RESult]? on page 151
10,5
Input amplitude
linear normalized
Compression Point (1 dB / 2
dB / 3 dB)
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 110).
In the graphical result, the compression points are indicated by horizontal red
lines.
FETCh:POWer:P1DB:CURRent[:RESult]? on page 153
FETCh:POWer:P2DB:CURRent[:RESult]? on page 154
FETCh:POWer:P3DB:CURRent[:RESult]? on page 154
Output Compression Point
(1 dB / 2 dB / 3 dB)
Output power where the gain deviates by 1 dB, 2 dB or 3 dB from a reference
gain.
Uses identical operating points as "Compression Point (1 dB / 2 dB / 3 dB)",
but is identified by output power at compression point rather than input power.
FETCh:POWer:P1DB:OUT:CURRent[:RESult]? on page 155
FETCh:POWer:P2DB:OUT:CURRent[:RESult]? on page 155
FETCh:POWer:P3DB:OUT:CURRent[:RESult]? on page 156
Occupied Bandwidth Occupied bandwidth calculated for the defined evaluation range.
Spectrum FFT
The "Spectrum FFT" result display shows the frequency spectrum of the signal.
The spectrum FFT result shows the signal level in the spectrum around the center fre-
quency. The unit is dBm.
You can display the spectrum of the measured signal and the reference signal. In the
best case, the measured signal has the same shape as the reference signal.
29User Manual 1179.3273.02 ─ 03
R&S®VSE-K18
Measurements and result displays
Remote command:
Selection (RF): LAY:ADD? '1',LEFT,RFS
Result query: TRACe<n>[:DATA]? on page 143
Time Domain
The "Time Domain" result display shows the signal characteristics over time.
It is similar to the "Power vs Time" and "Magnitude Capture" result displays in that it
shows the signal characteristics over time. However, it deliberately shows only a very
short period of the signal. You can thus use it to compare various aspects of the signal,
especially the timing of the displayed signals, in a single result display.
●
Measured signal
Trace 1 shows the characteristics of the measured signal over time. The data
should be the same as the results shown in the "Magnitude Capture" RF result display.
In the best case, the measured signal is the same as the reference signal.
●
Modeled signal
Trace 2 shows the characteristics of the modeled signal. When system modeling
has been turned off, this trace is not displayed.
If the model matches the behavior of the DUT, the characteristics of the signal are
the same as those of the measured signal (minus the noise).
●
Reference signal
Trace 3 shows the characteristics of the reference signal. The reference signal
present at the DUT input represents the ideal signal.
Remote command:
Selection: LAY:ADD? '1',LEFT,TDOM
Result query: TRACe<n>[:DATA]? on page 143
Scale of the x-axis (display settings for the time domain) ← Time Domain
The scale of the x-axis depends on your configuration in the "Display Settings" dialog
box.
The logic is as follows:
●
When you select automatic scaling (➙ "Position: Auto") and synchronization has
failed, the application searches for the peak level in the capture buffer and shows
the signal around the peak for the "Duration" that has been defined.
●
When you select automatic scaling (➙ "Position: Auto") and synchronization is OK,
the application searches for the peak level in the synchronized area of the capture
30User Manual 1179.3273.02 ─ 03
Loading...