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R&S®FSW-K30
Noise Figure Measurements
User Manual
(;×êÔ2)
1173927002
Version 29
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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)
This manual applies to the following R&S®FSW models with firmware version 3.20 and higher:
●
R&S®FSW8 (1312.8000K08)
●
R&S®FSW13 (1312.8000K13)
●
R&S®FSW26 (1312.8000K26)
●
R&S®FSW43 (1312.8000K43)
●
R&S®FSW50 (1312.8000K50)
●
R&S®FSW67 (1312.8000K67)
●
R&S®FSW85 (1312.8000K85)
The following firmware options are described:
●
R&S FSW-K30 (1313.1380.02)
© 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.
1173.9270.02 | Version 29 | R&S®FSW-K30
Throughout this manual, products from Rohde & Schwarz are indicated without the ® symbol , e.g. R&S®FSW is indicated as
R&S FSW.
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R&S®FSW-K30
1 Preface.................................................................................................... 7
1.1 About this manual.........................................................................................................7
1.2 Conventions used in the documentation....................................................................8
1.2.1 Typographical conventions..............................................................................................8
1.2.2 Conventions for procedure descriptions..........................................................................8
1.2.3 Notes on screenshots..................................................................................................... 8
2 Welcome to the noise figure measurement application.....................9
2.1 Starting the noise application......................................................................................9
2.2 Understanding the display information.................................................................... 10
3 Measurements and result displays.................................................... 13
Contents
Contents
4 Measurement basics............................................................................22
4.1 Tuning modes.............................................................................................................. 22
4.1.1 Swept measurements................................................................................................... 23
4.1.2 Frequency table measurements....................................................................................23
4.1.3 Single frequency measurements...................................................................................23
4.2 Measurement modes.................................................................................................. 24
4.3 DUT types.................................................................................................................... 26
4.3.1 Measurements on linear DUTs (direct measurement)...................................................26
4.3.2 Measurements on frequency converting DUTs............................................................. 26
4.4 External generator control......................................................................................... 27
4.5 Image frequency rejection..........................................................................................29
4.6 Calibration (2nd stage correction).............................................................................32
4.7 Using smart noise sources........................................................................................ 35
4.8 Separating signals by selecting an appropriate resolution bandwidth................. 35
4.9 Analyzing several traces - trace mode......................................................................36
4.10 Using markers............................................................................................................. 37
5 Configuration........................................................................................40
5.1 Configuration overview.............................................................................................. 40
5.2 Defining the measurement frequency.......................................................................42
5.2.1 Defining a frequency set............................................................................................... 42
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5.2.2 Configuring single frequency measurements................................................................45
5.2.3 Using a frequency table................................................................................................ 46
5.3 Selecting DUT characteristics................................................................................... 49
5.4 Configuring the noise source.................................................................................... 50
5.4.1 Defining the noise source characteristics......................................................................50
5.4.2 Using an ENR or temperature table.............................................................................. 54
5.5 Configuring additional loss........................................................................................58
5.5.1 Defining loss..................................................................................................................58
5.5.2 Using a loss table..........................................................................................................61
5.6 Configuring the analyzer............................................................................................ 63
5.7 Using the uncertainty calculator............................................................................... 67
5.7.1 Configuring noise source characteristics...................................................................... 69
5.7.2 Configuring DUT characteristics................................................................................... 70
Contents
5.7.3 Configuring analyzer characteristics............................................................................. 71
5.7.4 Guidelines and results...................................................................................................72
5.8 Trigger and gate configuration.................................................................................. 74
5.8.1 Trigger settings..............................................................................................................74
5.8.2 Gate settings................................................................................................................. 78
5.8.3 Continuous gate settings...............................................................................................79
5.9 Performing measurements.........................................................................................80
5.10 Configuring inputs and outputs of the R&S FSW.................................................... 82
5.10.1 Radio frequency (RF) input........................................................................................... 83
5.10.2 External generator.........................................................................................................85
5.10.2.1 Interface configuration settings..................................................................................... 85
5.10.2.2 Measurement configuration...........................................................................................86
6 Analysis................................................................................................ 90
6.1 Configuring the display.............................................................................................. 90
6.1.1 Configuring graphical results.........................................................................................90
6.1.2 Configuring numerical results........................................................................................92
6.2 Working with traces.................................................................................................... 93
6.3 Using markers............................................................................................................. 96
6.3.1 Marker configuration..................................................................................................... 96
6.3.2 Marker positioning.........................................................................................................99
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6.4 Limit line settings and functions............................................................................. 101
6.4.1 Limit line management................................................................................................ 101
6.4.2 Limit line details...........................................................................................................103
7 Remote control commands for noise figure measurements......... 106
7.1 Common suffixes...................................................................................................... 107
7.2 Introduction............................................................................................................... 107
7.2.1 Conventions used in descriptions............................................................................... 108
7.2.2 Long and short form.................................................................................................... 108
7.2.3 Numeric suffixes..........................................................................................................109
7.2.4 Optional keywords.......................................................................................................109
7.2.5 Alternative keywords................................................................................................... 109
7.2.6 SCPI parameters.........................................................................................................110
Contents
7.2.6.1 Numeric values............................................................................................................110
7.2.6.2 Boolean........................................................................................................................111
7.2.6.3 Character data.............................................................................................................111
7.2.6.4 Character strings......................................................................................................... 112
7.2.6.5 Block data....................................................................................................................112
7.3 Controlling the noise figure measurement channel.............................................. 112
7.4 Working with windows in the display......................................................................116
7.5 General window commands.....................................................................................123
7.6 Retrieving measurement results............................................................................. 123
7.7 Defining the measurement frequency.....................................................................125
7.8 Selecting DUT characteristics................................................................................. 130
7.9 Configuring the noise source.................................................................................. 132
7.10 Configuring additional loss......................................................................................140
7.11 Configuring the analyzer..........................................................................................147
7.12 Configuring triggered and gated measurements...................................................154
7.12.1 Configuring the triggering conditions...........................................................................154
7.12.2 Configuring gated measurements............................................................................... 159
7.12.3 Configuring the trigger output......................................................................................164
7.12.4 Programming example: continuous gating..................................................................166
7.13 Using the uncertainty calculator............................................................................. 167
7.14 Performing measurements.......................................................................................177
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7.15 Configuring the inputs and outputs........................................................................ 182
7.15.1 Radio frequency (RF) input......................................................................................... 182
7.15.2 External mixer............................................................................................................. 185
7.15.3 External generator.......................................................................................................196
7.16 Configuring the display............................................................................................ 200
7.17 Working with traces.................................................................................................. 203
7.18 Working with limit lines............................................................................................ 208
7.18.1 Defining general characteristics of a limit line............................................................. 209
7.18.2 Defining horizontal data points....................................................................................210
7.18.3 Controlling lower limit lines..........................................................................................212
7.18.4 Controlling upper limit lines......................................................................................... 213
7.18.5 Managing limit lines.....................................................................................................214
7.18.6 Controlling limit checks............................................................................................... 215
Contents
7.19 Working with markers...............................................................................................217
7.19.1 Using markers............................................................................................................. 218
7.19.2 Using delta markers.................................................................................................... 220
7.19.3 Configuring markers....................................................................................................223
7.19.4 Positioning markers.....................................................................................................224
7.19.5 Positioning delta markers............................................................................................226
7.20 Using the status register.......................................................................................... 228
7.20.1 Status registers for noise figure measurements..........................................................229
7.20.1.1 STATus:OPERation register........................................................................................231
7.20.1.2 STATus:QUEStionable register................................................................................... 231
7.20.1.3 STATus:QUEStionable:LIMit register.......................................................................... 232
7.20.1.4 STATus:QUEStionable:CORRection register..............................................................232
7.20.1.5 Status register remote commands.............................................................................. 233
7.21 Deprecated remote commands for noise figure measurements.......................... 235
7.22 Programming example: measuring a noise figure.................................................236
Annex.................................................................................................. 237
A Reference: frequency table file format.............................................237
List of Commands (Noise Figure).....................................................238
Index....................................................................................................245
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1 Preface
1.1 About this manual
Preface
About this manual
This User Manual provides all the information specific to the application. All general
instrument functions and settings common to all applications and operating modes are
described in the main R&S FSW User Manual.
The main focus in this manual is on the measurement results and the tasks required to
obtain them. The following topics are included:
●
Welcome to the "Noise Figure" Application
Introduction to and getting familiar with the application
●
Typical applications
Example measurement scenarios in which the application is frequently used.
●
Measurements and Result Displays
Details on supported measurements and their result types
●
"Noise Figure" Measurement Basics
Background information on basic terms and principles in the context of the measurement
●
"Noise Figure" Measurement Configuration + Analysis
A concise description of all functions and settings available to configure measurements and analyze results with their corresponding remote control command
●
How to Perform Measurements with the "Noise Figure" Application
The basic procedure to perform each measurement and step-by-step instructions
for more complex tasks or alternative methods
●
Measurement Examples
Detailed measurement examples to guide you through typical measurement scenarios and allow you to try out the application immediately
●
Optimizing and Troubleshooting the Measurement
Hints and tips on how to handle errors and optimize the test setup
●
Remote Commands for "Noise Figure" Measurements
Remote commands required to configure and perform "noise figure" measurements
in a remote environment, sorted by tasks
(Commands required to set up the environment or to perform common tasks on the
instrument are provided in the main R&S FSW User Manual)
Programming examples demonstrate the use of many commands and can usually
be executed directly for test purposes
●
Annex
Reference material
●
List of remote commands
Alphabetical list of all remote commands described in the manual
●
Index
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1.2 Conventions used in the documentation
1.2.1 Typographical conventions
Preface
Conventions used in the documentation
The following text markers are used throughout this documentation:
Convention Description
"Graphical user interface elements"
[Keys] Key and knob names are enclosed by square brackets.
Filenames, commands,
program code
Input Input to be entered by the user is displayed in italics.
Links Links that you can click are displayed in blue font.
"References" References to other parts of the documentation are enclosed by quota-
All names of graphical user interface elements on the screen, such as
dialog boxes, menus, options, buttons, and softkeys are enclosed by
quotation marks.
Filenames, commands, coding samples and screen output are distinguished by their font.
tion marks.
1.2.2 Conventions for procedure descriptions
When operating the instrument, several alternative methods may be available to perform the same task. In this case, the procedure using the touchscreen is described.
Any elements that can be activated by touching can also be clicked using an additionally connected mouse. The alternative procedure using the keys on the instrument or
the on-screen keyboard is only described if it deviates from the standard operating procedures.
The term "select" may refer to any of the described methods, i.e. using a finger on the
touchscreen, a mouse pointer in the display, or a key on the instrument or on a keyboard.
1.2.3 Notes on screenshots
When describing the functions of the product, we use sample screenshots. These
screenshots are meant to illustrate as many as possible of the provided functions and
possible interdependencies between parameters. The shown values may not represent
realistic usage scenarios.
The screenshots usually show a fully equipped product, that is: with all options installed. Thus, some functions shown in the screenshots may not be available in your particular product configuration.
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R&S®FSW-K30
2 Welcome to the noise figure measurement
Welcome to the noise figure measurement application
Starting the noise application
application
The R&S FSW-K30 is a firmware application that adds functionality to perform "noise
figure" measurements to the R&S FSW.
Noise Source Control
The Noise Source Control connector on the R&S FSW is a prerequisite for the R&S
FSW Noise measurements application.
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 Spectrum application 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 noise application....................................................................................9
● Understanding the display information....................................................................10
2.1 Starting the noise application
The "noise figure" measurement application adds a new type of measurement to the
R&S FSW.
To activate the R&S FSW Noise measurements application
1. Select the [MODE] key.
A dialog box opens that contains all operating modes and applications currently
available on your R&S FSW.
2. Select the "Noise Figure" item.
The R&S FSW opens a new measurement channel for the "noise figure" measurement application.
All settings specific to "noise figure" measurements are in their default state.
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Welcome to the noise figure measurement application
Understanding the display information
Multiple Channels and Sequencer Function
When you activate an application, a new channel is created which determines the
measurement settings for that application ("Channel"). The same application can be
activated with different measurement settings by creating several "Channel"s for the
same application.
The number of channels that can be configured at the same time depends on the available memory on the instrument.
Only one measurement can be performed at any time, namely the one in the currently
active channel. However, to perform the configured measurements consecutively, a
Sequencer function is provided.
If activated, the measurements configured in the currently defined "Channel"s are performed one after the other in the order of the tabs. The currently active measurement is
indicated by a
The result displays of the individual channels are updated in the tabs (as well as the
"MultiView") as the measurements are performed. Sequential operation itself is independent of the currently displayed tab.
symbol in the tab label.
For details on the Sequencer function, see the R&S FSW user manual.
2.2 Understanding the display information
The following figure shows the display as it looks for "noise figure" measurements. All
different information areas are labeled. They are explained in more detail in the following sections.
1
2
3
4
4
4 4
6
Figure 2-1: Screen layout of the noise figure measurement application
5
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Welcome to the noise figure measurement application
Understanding the display information
1 = Toolbar
2 = Channel bar
3 = Diagram header
4 = Result display
5 = Softkey bar
6 = Status bar
Channel bar information
In the R&S FSW Noise measurements application, the R&S FSW shows the following
settings:
Ref Level Reference level of the R&S FSW.
Att Attenuation of the R&S FSW.
RBW Resolution bandwidth
SWT Sweep time
AVG Number of averages
ENR Excess noise ratio
For smart noise sources: also the provided temperature
2nd Stage Corr State of the 2nd stage correction.
Calibration Data Date and time of the current calibration data.
Mode Currently selected measurement mode.
Window title bar information
For each diagram, the header provides the following information:
Figure 2-2: Window title bar information for the R&S FSW Noise measurements application
1 = Window number
2 = Window type
3 = Trace color and number
4 = Trace mode
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.
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Welcome to the noise figure measurement application
Understanding the display information
Risk of damaging the instrument
Make sure not to overload the input mixer during calibration and the measurement. An
overload condition can damage or destroy the input mixer.
If an overload condition occurs, the R&S FSW shows a corresponding message in the
status line ("RF OVLD" or "IF OVLD").
To avoid an overload during calibration or measurement, do one or more of the following:
●
Check and adjust the DUT "gain" settings
●
Check and adjust the ENR settings
●
Increase the reference level.
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3 Measurements and result displays
Measurements and result displays
The R&S FSW-K30 measures the "noise figure" of a DUT and displays the results
graphically and numerically. Each graphical result display shows the "noise figure" from
a different perspective. In the default configuration, the application shows the "noise
figure" of the DUT, the "gain" of the DUT and the corresponding "y-factor". In addition,
it shows the numerical results of the measurement.
The scale of the horizontal axis depends on the tuning mode.
Frequency list and swept measurements
In all graphical result displays, the horizontal axis represents the frequency. The displayed frequency is either the RF (radio frequency) or the IF (intermediate frequency).
The range depends on the frequency set you have currently defined. Because the
application only measures selected frequencies, it connects the results to draw a trace.
Negative "noise figure" and "noise temperature"
From a physical point of view, the "noise figure" and the "noise temperature" levels
have a positive range (including zero).
Due to the mathematical operations the application performs, the results can be negative. Sometimes this happens due to incorrect calibration or variance of measurement
values.
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out
in
SNR
SNR
Figure Noise
Measurements and result displays
Single frequency measurements
In all graphical result displays, the horizontal axis represents a chronological order of
measurement results for the frequency you are testing. The axis has no unit, but is
made up out of several index values that represent time. Each index value represents
one measurement point and therefore one measurement on the single frequency you
are analyzing. The size of the index (and thus number of results) depends on the number of (Measurement) Points that you have defined. Because the application only
measures at certain points in time, it connects the results to draw a trace.
The right diagram border represents the present (index = 0), values to the left represent past measurement results (index = -<x>). As soon as the application finishes a
single measurement, the measurement points are moved to the left, the new result is
added on the right. All other measurement points are moved down one position with
the most obsolete result falling out of the diagram (like in the roll mode of an oscilloscope).
Selecting the result display
►
Select the
icon in the toolbar or press the [MEAS] key.
The application enters the SmartGrid configuration mode.
For more information on the SmartGrid functionality, see the R&S FSW Getting
Started.
Noise Figure..................................................................................................................14
Gain...............................................................................................................................15
Noise Temperature........................................................................................................15
Y-Factor.........................................................................................................................16
ENR Measured..............................................................................................................17
Power (Hot)...................................................................................................................18
Power (Cold)................................................................................................................. 18
Cal Y-Factor.................................................................................................................. 19
Cal Power (Hot).............................................................................................................19
Cal Power (Cold)...........................................................................................................20
Result Table.................................................................................................................. 20
Current Values...............................................................................................................21
Marker Table................................................................................................................. 21
Noise Figure
Shows the "noise figure" of the DUT.
The "noise figure" is the ratio of the signal-to-noise ratio at the DUT input to the signal-
to-noise ratio at the DUT output.
The vertical axis shows the level of the "noise figure" in dB. The scale depends on the
settings in the "Display Configuration" dialog box.
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Measurements and result displays
Remote command:
LAY:ADD:WIND? '2',RIGH,NOIS see LAYout:ADD[:WINDow]? on page 117
Results:TRACe<t>[:DATA]? <Trace>,NOISe
Gain
Shows the "gain" characteristics of the DUT.
The vertical axis shows the level of the "gain" in dB. The scale depends on the settings
in the "Display Configuration" dialog box.
Remote command:
LAY:ADD:WIND? '2',RIGH,GAIN see LAYout:ADD[:WINDow]? on page 117
Results:TRACe<t>[:DATA]? <Trace>,GAIN
Noise Temperature
Shows the "noise temperature" characteristics of the DUT.
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constant Boltzmannk
BandwidthB
PowerP
with
eTemperatur Noise
kB
P
off source noise with[dB] power Noise
on source noise with[dB] power Noise
with
FactorY
off
on
off
on
N
N
N
N
Measurements and result displays
The vertical axis shows the "noise temperature" in Kelvin. The scale depends on the
settings in the "Display Configuration" dialog box.
Remote command:
LAY:ADD:WIND? '2',RIGH,TEMP see LAYout:ADD[:WINDow]? on page 117
Results: TRACe<t>[:DATA]? <Trace>,TEMPerature
Y-Factor
Shows the ratio of the hot and the cold power of the DUT.
The "Y-factor" indicates the quality of measurement tolerances and uncertainties. To
get the result, the application measures the DUT power with the noise source turned
on (hot power) and the noise source turned off (cold power).
The vertical axis shows the linear relation. The scale depends on the settings in the
"Display Configuration" dialog box.
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Measurements and result displays
Remote command:
LAY:ADD:WIND? '2',RIGH,YFAC see LAYout:ADD[:WINDow]? on page 117
Results: TRACe<t>[:DATA]? <Trace>,YFACtor
ENR Measured
Shows the results of the ENR measurement.
To measure the ENR of a noise source, first attach a noise source with known ENR to
the device, enter the ENR of this noise source to the calibration ENR table and calibrate using this one. Then, attach the unknown noise source to the device and perform
a measurement ("Run Single") with this one. The graph shown in the ENR Measured
display and the results for ENR Measured in the Result Summary will be the ENR of
the noise source at the measured frequencies. The vertical axis shows the level of the
measured ENR in dB. The scale depends on the settings in the "Display Configuration"
dialog box.
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Measurements and result displays
Remote command:
LAY:ADD:WIND? '2',RIGH,ENR see LAYout:ADD[:WINDow]? on page 117
Results: TRACe<t>[:DATA]? <Trace>,ENR
Power (Hot)
Shows the absolute power characteristics at the instrument input. The noise source is
turned on.
The vertical axis shows the power in dBm. The scale depends on the settings in the
"Display Configuration" dialog box.
Remote command:
LAY:ADD:WIND? '2',RIGH,PHOT see LAYout:ADD[:WINDow]? on page 117
Results: TRACe<t>[:DATA]? <Trace>,PHOT
Power (Cold)
Shows the absolute power characteristics at the instrument input. The noise source is
turned off.
The vertical axis shows the power in dBm. The scale depends on the settings in the
"Display Configuration" dialog box.
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off source noise with[dB] power Noise
on source noise with[dB] power Noise
with
FactorY
off
on
off
on
N
N
N
N
Measurements and result displays
Remote command:
LAY:ADD:WIND? '2',RIGH,PCOL see LAYout:ADD[:WINDow]? on page 117
Results: TRACe<t>[:DATA]? <Trace>,PCOLd
Cal Y-Factor
Shows the ratio of the hot and the cold power measured during calibration.
The "Y-factor" indicates the quality of measurement tolerances and uncertainties. To
get the result, the application measures the power with the noise source turned on (hot
power) and the noise source turned off (cold power), but without the DUT inserted.
The vertical axis shows the linear relation. The scale depends on the settings in the
"Display Configuration" dialog box.
Remote command:
LAY:ADD:WIND? '2',RIGH,CYF see LAYout:ADD[:WINDow]? on page 117
Results: TRACe<t>[:DATA]? <Trace>,CYFactor
Cal Power (Hot)
Shows the absolute power characteristics at the instrument input during the calibration
measurement. The noise source is turned on, the DUT is not inserted.
The vertical axis shows the power in dBm. The scale depends on the settings in the
"Display Configuration" dialog box.
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Measurements and result displays
Remote command:
LAY:ADD:WIND? '2',RIGH,CPH see LAYout:ADD[:WINDow]? on page 117
Results: TRACe<t>[:DATA]? <Trace>,CPHot
Cal Power (Cold)
Shows the absolute power characteristics at the instrument input during the calibration
measurement. The noise source is turned off, the DUT is not inserted.
The vertical axis shows the power in dBm. The scale depends on the settings in the
"Display Configuration" dialog box.
Remote command:
LAY:ADD:WIND? '2',RIGH,CPC see LAYout:ADD[:WINDow]? on page 117
Results: TRACe<t>[:DATA]? <Trace>,CPCold
Result Table
Shows the measurement results in numerical form in a table.
The contents of the table depend on the "Display Settings". By default it shows the
"noise figure", "gain" and "y-factor" results. Each row represents one measurement
point. Each column represents one result type. The first column shows the measurement frequency.
If you display the uncertainty result, it is displayed in the "Noise" column next to the
"Noise Figure" result. Note that the uncertainty is displayed only after you have turned
on the uncertainty calculation and also include the result in the display.
The result table shows either the RF or the IF, depending on your selection.
For more information, see Chapter 6.1.2, "Configuring numerical results", on page 92.
Remote command:
LAY:ADD:WIND? '2',RIGH,RES see LAYout:ADD[:WINDow]? on page 117
Results: TRACe<n>[:DATA]? on page 124
Table items: DISPlay[:WINDow<n>]:TABLe:ITEM on page 200
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Measurements and result displays
Current Values
Shows the result at the current measurement point.
The contents of the "Current" result display are updated as soon as a new measure-
ment point is analyzed.
The result types shown in the table depend on the "Display Settings". By default it
shows the results for the "Noise Figure", "Gain" and "Y-Factor" result type. Each row
represents one result type. The first column shows the result type, the second column
shows the result.
For more information, see Chapter 6.1.2, "Configuring numerical results", on page 92.
Marker Table
Shows the marker characteristics in numerical form in a table.
The size of the table depends on the number of active markers and the way you have
configured the table in the "Result Config" dialog box. For more information, see Chap-
ter 6.3, "Using markers", on page 96 and Chapter 6.1.2, "Configuring numerical
results", on page 92.
The first four columns of the table are fix.
●
Type
Shows the marker type. 'M' represents a normal marker, 'D' represents a delta
marker.
●
Ref
Shows the reference marker for relative delta markers.
●
Trc
Shows the trace that the marker is positioned on.
●
X-value
Shows the horizontal position (frequency) of the marker.
For normal markers, the position is an absolute value. The position of delta markers is relative to another marker.
●
<Result>
Shows the measurement result at the marker position.
For normal markers, the result is an absolute value. Results for delta markers are
relative to another marker.
Remote command:
LAY:ADD:WIND? '2',RIGH,MTAB see LAYout:ADD[:WINDow]? on page 117
Results:
CALCulate<n>:MARKer<m>:Y? on page 219
CALCulate<n>:DELTamarker<m>:Y? on page 222
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4 Measurement basics
Measurement basics
Tuning modes
The measurement basics contain background information on the terminology and principles of "noise figure" measurements.
"Noise figure" measurements determine the noise that a device under test (DUT) adds
to a signal as that signal passes through the DUT.
● Tuning modes......................................................................................................... 22
● Measurement modes.............................................................................................. 24
● DUT types............................................................................................................... 26
● External generator control.......................................................................................27
● Image frequency rejection.......................................................................................29
● Calibration (2nd stage correction)...........................................................................32
● Using smart noise sources......................................................................................35
● Separating signals by selecting an appropriate resolution bandwidth.................... 35
● Analyzing several traces - trace mode....................................................................36
● Using markers.........................................................................................................37
4.1 Tuning modes
Basically, the application calculates the "noise figure" of a DUT based on the characteristics of the DUT that have been measured and a noise source whose properties are
known. Therefore, the Noise Source Control connector on the R&S FSW is a prerequisite for the R&S FSW Noise measurements application.
In addition to the noise characteristics of a DUT, the application is also able to determine several more DUT characteristics like its "gain" or its "noise temperature" characteristics.
The application provides several measurement modes or tuning modes.
● Swept measurements............................................................................................. 23
● Frequency table measurements..............................................................................23
● Single frequency measurements.............................................................................23
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4.1.1 Swept measurements
Measurement basics
Tuning modes
The sweep tuning mode performs measurements on a set of discrete frequencies
based on the frequency parameters. Each measurement analyzes the noise characteristics of the corresponding frequency or measurement point.
For swept measurements, the application automatically determines the measurement
frequencies and combines them in a frequency list.
Such a frequency set is the result of the frequency and span information that you have
provided. The frequency and span information is made up out of the center frequency,
the span, the start and the stop frequency. In combination with the measurement points
or the frequency table step size, the application calculates the contents of the frequency table.
The center frequency is the frequency in the center of the frequency band you are
measuring. Thus, it is defined either by the span, or the start and stop frequencies.
The measurement points is the number of entries in a frequency list and thus the
number of measurements that the application performs during a "noise figure" measurement.
The stepsize defines the distance between two measurement points. It is constant for
all measurement points.
If the stepsize is larger than the distance between start and stop frequency, the frequency table consists of the start and stop frequencies only.
4.1.2 Frequency table measurements
The frequency table tuning mode also performs measurements on a set of frequencies based on the contents of a frequency list. Each measurement analyzes the noise
characteristics of the corresponding frequency.
Compared to a swept measurement, you can customize the contents of the frequency
list. Thus, you can add frequencies that are independent of the frequency stepsize and
the number of measurement points.
Frequency tables also allow you to define a variable RBW and sweep time, depending
on the current frequency of the sweep point (see "Variable RBW and sweep time for
low-frequency measurements" on page 36 and Chapter 5.2.3, "Using a frequency
table", on page 46).
4.1.3 Single frequency measurements
The single frequency tuning mode performs one or several consecutive measurements on a single frequency. You can perform the measurement on any frequency that
is supported by the hardware you are using.
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Measurement basics
Measurement modes
Single frequency measurements are a way to facilitate manual adjustments for "noise
figure" measurements. They also allow you to get an idea about how the "noise figure"
at a particular frequency change over time.
Note that sweep lists or frequency tables are not considered in this measurement
mode.
Single frequency measurement results
For single frequency measurements, the same set of graphical result displays is available as for frequency list measurements ("Noise Figure", "Gain" etc.). Note, however,
that the x-axis has no unit, but shows a series of results taken for a single frequency.
The number of displayed results depends on the number of measurement points you
have defined.
For more information, see Chapter 3, "Measurements and result displays", on page 13.
In addition, you can also view the results in the Result Table in numerical form.
Single frequency measurements are not available when you are using a resistor as a
noise source.
4.2 Measurement modes
In some cases, the Power (Hot) and Power (Cold) results require two different noise
sources with different temperature characteristics (cold and hot). Measurements with a
resistor noise source are such a case.
Usually, noise sources with diode characteristics are used for "Noise Figure" measurements. These noise sources have two states, on and off. When they are supplied with
power (state = on), the application measures the hot power, when they are not supplied
with power (state = off), it measures the cold power. Turning the noise source on and
off is automatically done by the application, so that you can get the hot and cold power
characteristics in a single step.
This automatic measurement mode is the default measurement mode of the R&S
FSW Noise measurements application.
A resistor noise source, however, requires two resistors, one hot and one cold. You
have to substitute the hot resistor by the cold resistor to measure first the hot and then
the cold power. For these cases, the application provides a manual measurement
mode. This measurement mode is automatically selected when you select a "Noise
Source" on page 52 with resistor characteristics, but is not restricted to those cases.
The manual measurement mode is available for measurements and the calibration
stage.
Performing a manual measurement
In manual measurement mode, you have to measure (or calibrate) the hot and cold
power characteristics of the DUT separately. When you start the measurement, the
application opens a dialog box that allows you to select the type of measurement to
perform next.
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Measurement basics
Measurement modes
Recommended order of measurements
Note that it is recommended that you begin with the hot power measurement.
Furthermore, calibration always begins with the hot power measurement.
In case the hot power has to be measured first, the cold power measurement is
unavailable:
When the first measurement is done, you can change the test setup by connecting the
other resistor. Then start the second measurement.
In the dialog box, the measurement stage that is already done is labeled green.
In addition, the application shows the missing calibration and measurement steps in
the channel bar.
Clearing results
To replace the previous calibration or measurement results, clear the currently stored
data using the "Clear Calibration Results" or "Clear Measurement Results" function.
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4.3 DUT types
Measurement basics
DUT types
Returning to automatic measurement mode
When you are in automatic measurement mode and select a noise source with resistor
characteristics, the application automatically selects the manual measurement mode.
When you are in manual measurement mode and select a noise source with diode
characteristics, you have to select the automatic measurement mode deliberately in
the "Sweep" menu.
"Noise figure" measurements are possible on DUTs with a wide variety of characteristics. The DUT characteristics not only affect the test setup, but also determine the way
the application populates the frequency list for swept measurements.
The R&S FSW Noise measurements application supports measurements on DUTs that
work on a fixed frequency as well as measurements on frequency-converting DUTs.
● Measurements on linear DUTs (direct measurement).............................................26
● Measurements on frequency converting DUTs....................................................... 26
4.3.1 Measurements on linear DUTs (direct measurement)
For a linear DUT, the RF frequency remains the same between its input and output.
For measurements on such DUTs, it is sufficient to measure the signal's RF frequency
without any additional equipment (like a local oscillator). A typical linear DUT is an
amplifier, for example.
The test setup for measurements on such DUTs usually consists of the noise source,
the DUT and an analyzer. If necessary, the measurement also considers loss that
occurs somewhere in the measurement path.
For linear DUTs, the contents and layout of the "Overview" dialog box represents the
configuration of a typical test setup.
4.3.2 Measurements on frequency converting DUTs
A frequency converting DUT converts the RF frequency to an intermediate frequency
(IF) using the local oscillator (LO). A frequency-converting DUT either converts the RF
frequency to a lower IF (down-conversion) or a higher IF (up-conversion).
The conversion process requires a local oscillator in the test setup. You can generate
the LO signal in two ways.
●
An external generator controlled by the analyzer via IEC bus.
●
A VCO controlled by a voltage source.
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Measurement basics
External generator control
If you have selected a frequency-converting DUT measurement mode, the layout of the
"Overview" dialog box adds the local oscillator to the test setup.
The local oscillator can have a fixed or a variable frequency. If the LO frequency is
fixed, the intermediate frequency (IF) resulting from the conversion process is variable
(depending on the input signal). If the LO frequency is variable, the IF has to be fixed.
The R&S FSW Noise measurements application provides measurement for both measurement scenarios.
Fixed intermediate frequency
If you select one of the fixed IF measurement modes, the IF is the same for all entries
in the frequency list. The LO frequency for each entry is variable and is the result of the
equation the selected mode is based on.
●
fRF - fIF for up-converters
●
fRF + fIF for down-converters
The fixed IF measurement modes are, for example, useful for measurements on mixers.
Note that fixed IF measurements are only possible if the R&S FSW is equipped with
the optional External Generator Control hardware. For more information, see Chap-
ter 4.4, "External generator control", on page 27.
Fixed LO frequency
If you select one of the fixed LO measurement modes, the LO frequency is the same
for all entries in the frequency list. The IF frequency for each entry is variable and is the
result of the equation the selected mode is based on.
●
fRF + fLO for up-converters
●
fRF - fLO for down-converters
The fixed LO measurement modes are, for example, required for measurements on
satellite converters.
4.4 External generator control
To perform fixed IF measurements with the R&S FSW Noise measurements application, you have to install the optional External Generator Control hardware. This option
allows you to control an external generator and the type of signal it generates.
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Measurement basics
External generator control
The typical measurement setup for such measurements includes the R&S FSW equipped with the optional R&S FSW Noise measurements application, a signal generator
and the DUT. The signal generator is controlled either via the LAN connection or the
GPIB interface. The GPIB interface is part of the optional External Generator Control
hardware.
To enhance the measurement accuracy, it is recommended to use a common reference frequency for both R&S FSW and signal generator in the measurement setup.
If you have no 10 MHz reference frequency on hand, you can use the internal reference signal of the R&S FSW or signal generator. For more information, see the documentation of the R&S FSW or the signal generator.
Signal generator support
The R&S FSW-B10 supports various signal generators. A list is available in the user
interface (see Generator Type) and in the documentation of the R&S FSW.
Note that you have to select the generator specifically for the R&S FSW Noise measurements application. It does not inherit the generator settings from other applications.
It is also possible to add new signal generators to that list. To do so, you have to copy
a custom signal generator setup file with the file extension .gen to the R&S FSW. The
setup file defines the frequency and power ranges supported by the generator, as well
as information required for communication. You can use a setup file of the signal generators already supported as a template. After you copy it to the R&S FSW, the new
generator model is added to the dropdown menu.
The existing setup files can be displayed in an editor in read-only mode directly from
the Interface Configuration dialog box.
Make sure to adhere to the required syntax and commands and only change the values of the parameters. Errors are only detected and displayed when you try to use the
custom generator.
Error and status messages
The following status and error messages can occur during external generator control.
Message Description
"Ext. Generator GPIB Handshake Error!" /
"Ext. Generator TCPIP Handshake Error!" /
"Ext. Generator TTL Handshake Error!"
"Ext. Generator Limits Exceeded!" The allowed frequency or power ranges for the generator
Connection to the generator is not possible, e.g. due to a
cable damage or loose connection or wrong address.
were exceeded.
"Reverse Sweep via min. Ext. Generator Frequency!"
"Ext. Generator File Syntax Error!" Syntax error in the generator setup file.
Reverse sweep is performed; frequencies are reduced to
the minimum frequency, then increased again.
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Image frequency rejection
Message Description
"Ext. Generator Command Error!" Missing or wrong command in the generator setup file.
"Ext. Generator Visa Error!!" Error with Visa driver provided with installation (very
unlikely).
Risk of damage to the instrument
To allow for highest sensitivity during the measurement, the R&S FSW Noise measurements application automatically sets the input attenuation to 0 dB.
Because this configuration minimizes the overrange reserve, make sure that the signal
you apply does not cause an overload condition. In particular, consider the LO feedthrough. An overload condition can damage or destroy the input mixer.
The R&S FSW shows a corresponding message in the status line if an overload occurs
("RF OVLD" or "IF OVLD").
To avoid an overload, do one of the following:
●
Reduce the LO feedthrough of the mixer device.
●
Increase the reference level.
4.5 Image frequency rejection
Frequency converting DUTs convert a radio frequency (RF) to an intermediate frequency (IF). The IF is lower than the RF for down-converting DUTs, and higher than
the RF for up-converting DUTs.
In a basic test setup, the image frequency of the RF signal is also converted to the IF.
Depending on the DUT, this effect can be wanted or even necessary, or not. To avoid
measurement errors of the "noise figure" and "gain" of up to 3 dB, make sure to use
the appropriate measurement configuration.
Basically, you can distinguish between single sideband (SSB) mixers, double sideband
(DSB) mixers, and mixers that partly suppress a sideband. If a sideband is not needed
or only partly needed, you can reject the image frequency. If you do so, the application
activates a filter that suppresses the image frequency to a certain extent.
The following illustrations help you configure the measurement correctly.
For more information on how to configure image rejection, see "Image Rejection"
on page 50.
Double sideband measurements
Double sideband mixers use both sidebands to the same extent. Both RF and image
frequency are converted. In that case, turn off image rejection.
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Image frequency rejection
fLO= frequency of the local oscillator
fIF= intermediate frequency = fRF ± f
fRF= lower sideband = fLO - f
f
= upper sideband = fLO + f
image
LO
IF
IF
If image rejection is on, the results have a 3 dB error. That means "noise figure" results
are 3 dB lower than they should be. "Gain" results are 3 dB higher.
Single sideband measurements
Single sideband mixers use a single sideband only. In that case, you have to suppress
the sideband that is not required. If you do so, the measurement is like on an amplifier.
To suppress a sideband completely, it is best to set the image rejection to the maximum amount possible (999.99 dB).
Partial sideband suppression
For measurements on mixers with a low image frequency rejection, there are two test
scenarios.
●
Mixers whose image rejection is known.
●
Mixers whose image rejection is unknown.
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Measurement basics
Image frequency rejection
For mixers whose image rejection is known, define the magnitude of image rejection in
dB as accurately as possible. Otherwise, measurement results ("noise figure" and
"gain") deviate between 0 dB to 3 dB.
If you do not know the image rejection characteristics of a mixer, use a custom test
setup including an additional filter. You also have to know the "gain" characteristics of
the DUT.
(1)
= Test setup for calibration
(2) = Test setup for "noise figure" measurement
In the test setup shown above, a lowpass filter prevents unwanted noise from being fed
in at the image frequency.
Depending on the position of the frequency bands, you might need a highpass or
bandpass filter for the RF frequency instead of the lowpass filter. The important point is
that unwanted noise is not converted by a further receive path of the mixer. The
unwanted noise at the receive frequency must not be reduced. The insertion loss must
be considered, if applicable.
With this test setup, the measurement on a mixer without sideband suppression is the
same as SSB measurements.
To take the characteristics of the filter into account, include the insertion loss of the filter at the RF. To consider the actual filter suppression at the image frequency, include
the actual attenuation for the image rejection.
Harmonics mixer measurement
For a harmonics mixer, the input signals are not only converted to the IF by the wanted
harmonic. The harmonic of the LO signal produced in the mixer is also converted.
Often, the mixer even features a lower conversion loss for unwanted harmonics. For
measurements on this type of mixer, you have to use a bandpass filter. The filter
ensures that there is only noise at the desired frequency at the input of the DUT. This
measurement is similar to measurements on a mixer with an average sideband suppression.
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4.6 Calibration (2nd stage correction)
Measurement basics
Calibration (2nd stage correction)
The calibration procedure of the application measures the inherent noise of the
R&S FSW you are using. Performing calibration is therefore recommended, as it
increases the accuracy of measurement results. The results get more accurate
because the application takes the inherent noise of the analyzer into account while it
calculates the results.
Calibration for "noise figure" measurements is also known as 2nd stage correction.
This term is used because in a typical "noise figure" test setup, the DUT represents the
first stage and the analyzer the second stage in the test setup.
The 2nd stage correction is a calibration that is specific to "noise figure" measurements. It is independent of the overall calibration state of the analyzer and does not
calibrate the analyzer.
For successful calibration, you need additional equipment.
●
Noise source
The noise source is like a calibration standard. It provides a reference with known
noise characteristics that allows the application to determine the inherent noise of
the analyzer you are using.
During the calibration, the application measures the inherent noise characteristics of
the analyzer at the set of measurement frequencies.
Thus, the 2nd stage correction is valid for a particular instrument configuration, the
room temperature and the instrument temperature. As long as this configuration stays
the same, calibration data remains valid.
Calibrating single frequency measurements
Like for all other measurements of the R&S FSW Noise measurements application,
perform a calibration before a single frequency measurement for increased accuracy.
There is an easy way to calibrate single frequency measurements, if you already calibrated the application for swept or list measurements. If the single frequency is part of
the frequency list, the measurement is already calibrated for that frequency and no further steps are necessary. The application recalls the last calibration values when you
switch back to sweep mode or frequency table mode.
Only if you use a single frequency that is not part of the frequency list, you must calibrate this frequency point first.
●
Interpolation
If you change the frequency, while the frequency span stays the same or is
reduced, the application interpolates the correction data for the new measurement
points. A new calibration is not required.
However, measurements based on interpolated data can result in an increased
measurement uncertainty. Highly accurate measurements that are conform to the
values specified in the data sheet are only possible at calibrated measurement
points.
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Calibration (2nd stage correction)
Note that useful interpolation is possible only if essential calibration parameters
(e.g. impedance or attenuation) change only slightly. This is the case if the distance
between the original calibration points is sufficiently small.
If the span increases compared to the span during calibration, a new calibration is
necessary.
If the application interpolates the calibration data, it shows a corresponding label in
the channel bar and a warning message in the status bar.
●
Invalid calibration
If you change one of the amplitude parameters (e.g. the attenuation), calibration is
labeled invalid. In that case, calibration is not accurate, because the settings are
not in line with the settings at the time the R&S FSW has been calibrated. If calibration is invalid, repeat the calibration or restore the settings as they were during
the calibration.
Saving calibration data
If you save the current configuration or measurement results to a data set, calibration
data is part of that data set.
For more information on saving and restoring data sets, see the "Storing and Recalling
Instrument Settings and Measurement Data" chapter in the R&S FSW user manual.
The picture below shows a typical calibration setup that includes a noise source.
Figure 4-1: Noise figure calibration setup
1. Connect the noise source directly and without a cable to the RF input of the analyzer.
2. Connect the noise source to the +28 V voltage supply (Noise Source Control connector) on the back of the R&S FSW.
To connect the noise source to the voltage supply, you need a coaxial cable.
After you have set up calibration, there are several ways to start calibration.
●
In the "Noise Overview" dialog box, press the "Calibrate" button.
●
In the "Sweep" menu, press the "Calibrate" softkey.
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Calibration (2nd stage correction)
Calibration Save
If the user has performed a valid calibration on the instrument, the calibration results
can be saved by using the "Calibration Save" button in the "Export" dialog. This provides the possibility to use once stored calibration results at a later point.
Remote command:
[SENSe:]CORRection:SAVE on page 149
Calibration Recall
Calibration results that have been stored once on the instrument can be recalled by
using the "Calibration Recall" button in the "Import" dialog.
To achieve a valid calibration by importing a saved one, all parameters of R&S FSWK30 must match exactly to the ones that have been used for the calibration. At the
import of a calibration, a preview dialog is shown which contains all relevant parameters of the calibration to be imported and an indication (green / red) if they match to the
current instrument and option settings. Only if the calibration context summary is
green, the calibration import can be done. If the calibration context summary is red,
importing the calibration results would lead to an invalid calibration status for the current settings. Thus the calibration results cannot be imported in this case. If the calibration context summary is green but some of the individual entries are red (i.e. they differ
from the current settings), the calibration results still can be imported. The import will
then overwrite the red marked settings with the ones from the stored calibration to
ensure the settings match.
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4.7 Using smart noise sources
Measurement basics
Separating signals by selecting an appropriate resolution bandwidth
Remote command:
[SENSe:]CORRection:RECall on page 149
A smart noise source (SNS) provides its own ENR and uncertainty tables and a temperature value from an internal measurement. Thus, accuracy is improved and less
configuration efforts are required.
When you connect a smart noise source, the R&S FSW automatically loads its ENR
table and stores it for future measurements. The ENR table remains stored on the
instrument even after the noise source is disconnected. If the table already exists on
the R&S FSW, the contents are updated, if necessary. The contents of the most
recently loaded SNS ENR table are also stored as the "default" ENR table. Thus, they
remain available even if the noise source type is changed, for example to "noise
diode". The ENR tables for smart noise sources are shown for reference only and cannot be edited in the R&S FSW Noise measurements application. The name of each
ENR table contains the serial number of the SNS.
Test Setup
Connect the smart noise source to the Lemosa Power Sensor / Noise Source Control
connector on the R&S FSW. (For models without a Lemosa connector, connect the
SNS to the BNC Noise source control connector and a USB connector on the
R&S FSW.) Then connect the SNS output to the DUT or the RF Input connector on the
R&S FSW. Only one SNS can be active on the R&S FSW at any time.
The identification and setup procedure after connecting the FS-SNS may take up to 10
seconds.
4.8 Separating signals by selecting an appropriate resolution bandwidth
The resolution bandwidth defines the 3 dB bandwidth of the resolution filter to be used.
An RF sinusoidal signal is displayed according to the passband characteristic of the
resolution filter (RBW), i.e. the signal display reflects the shape of the filter.
The highest sensitivity is obtained at the smallest bandwidth (1 Hz). If the bandwidth is
increased, the reduction in sensitivity is proportional to the change in bandwidth.
Increasing the bandwidth by a factor of 3 increases the displayed noise by approx. 5
dB (4.77 dB precisely). If the bandwidth is increased by a factor of 10, the displayed
noise increases by a factor of 10, i.e. 10 dB.
The higher spectral resolution with smaller bandwidths is won by longer sweep times
for the same span. The sweep time has to allow the resolution filters to settle during a
sweep at all signal levels and frequencies to be displayed.
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Analyzing several traces - trace mode
If the RBW is too large, signal parts that are very far away (e.g. from a different signal)
are considered in the measurement and distort the results. The displayed noise increases.
If the RBW is too small, the measurement time increases.
Variable RBW and sweep time for low-frequency measurements
Usually, a constant RBW and sweep time is used for the entire measurement. However, for low-frequency measurements (under 10 MHz), smaller bandwidths and longer
sweep times are required to improve accuracy of the results. Using a small RBW and
long sweep time for the entire span would increase measurement time significantly. In
this case, a variable RBW and sweep time can be defined for lower frequencies,
depending on the current frequency of the sweep point. The variable RBW and sweep
times are defined in the frequency table (see Chapter 5.2.3, "Using a frequency table",
on page 46). The defined RBW and sweep times are also included in a table export.
In the channel bar, the bandwidth and sweep time range of the variable values is indicated.
4.9 Analyzing several traces - trace mode
The trace mode determines the way the data is processed and displayed. The application provides the following trace modes.
Table 4-1: Overview of available trace modes
Trace Mode Description
Blank Hides the selected trace.
Clear Write Overwrite mode: the trace is overwritten by each sweep. This is the default setting.
View The current contents of the trace memory are frozen and displayed.
Each time the trace mode is changed, the selected trace memory is cleared.
The default trace mode for the first trace is Clear/Write. For trace 2-4, the default trace
mode is "Blank". If you require another mode, you have to set it manually.
As you can have up to four traces simultaneously, you can compare the results with
different measurement configurations. For example, freeze a trace and use it as a reference trace.
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Using markers
If you change the scaling of the y-axis, the R&S FSW automatically adapts the trace
data to the changed display range. Thus, you can perform an amplitude zoom after the
measurement to show details of the trace.
4.10 Using markers
Markers are used to mark points on traces, to read out the results of a particular measurement point or compare results of different traces. The noise application provides
four markers.
When you activate a marker, the application automatically positions it on the first measurement point (left border of the diagram) of trace 1, regardless of how many traces
are active. A marker is always positioned on the same horizontal position in all active
measurement windows. If you change the position of a marker in one window, the
application adjusts the position of that marker in all other measurement windows. Thus,
the marker results for a specific marker are always for the same frequency, which
makes it easier to compare results.
Markers in single frequency mode
When you use a marker for single frequency measurements, the marker is positioned
on a particular index value and not a particular measurement point. This means that
during continuous measurements, the marker remains on the index value you have put
it on. It does not move down the line with the results.
To move a marker, you can use several methods.
●
Enter a particular measurement frequency in the input field that opens when you
activate a marker.
●
Move the marker around with the rotary knob or the cursor keys.
●
Drag the marker around using the touchscreen.
All markers can be used either as normal markers or delta markers. A normal marker
indicates the absolute signal value at the defined position in the diagram. A delta
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Using markers
marker indicates the value of the marker relative to the specified reference marker (by
default marker 1).
The application always positions the marker on the trace with the lowest number that is
in Clear/Write trace mode. To set the marker on another trace, use the "Marker to
Trace" function. With this function, you can also position a marker on a trace that is in
"View" trace mode, e.g. to compare measurement results. Note that at least one active
marker has to be a normal marker.
The application shows the results at the marker position directly in the diagram area
(up to two markers) or in the marker table (if you use more than two markers).
Marker information in diagram area
By default, the results of the last two markers or delta markers that were activated are
displayed in the diagram area.
The following information is displayed there:
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Using markers
●
The marker type (M for normal, D for delta, or special function name)
●
The marker number (1 to 4)
●
The assigned trace number in square brackets [ ]
●
The marker value on the y-axis
●
The marker position on the x-axis
Marker information in marker table
In addition to the marker information displayed within the diagram area, a marker table
can be displayed in a separate window. For more information on the contents of the
marker table, see "Marker Table" on page 21.
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5 Configuration
Configuration
Configuration overview
"Noise figure" measurements require a special application on the R&S FSW, which you
activate using the [MODE] key.
The Noise Source Control connector on the R&S FSW is also a prerequisite for the
R&S FSW Noise measurements application. Without this connector, no measurement
can be performed.
When you activate a measurement channel in the R&S FSW Noise measurements
application, a measurement for the input signal is defined with the default configuration. The "Noise Figure" menu is displayed and provides access to the most important
configuration functions.
Unavailable hardkeys
Note that the [AMPT], [AUTO SET], [BW], [TRIG] and [MKR FUNC] keys have no contents and no function in the R&S FSW Noise measurements application.
● Configuration overview............................................................................................40
● Defining the measurement frequency..................................................................... 42
● Selecting DUT characteristics.................................................................................49
● Configuring the noise source.................................................................................. 50
● Configuring additional loss......................................................................................58
● Configuring the analyzer......................................................................................... 63
● Using the uncertainty calculator..............................................................................67
● Trigger and gate configuration................................................................................ 74
● Performing measurements......................................................................................80
● Configuring inputs and outputs of the R&S FSW....................................................82
5.1 Configuration overview
Throughout the measurement channel configuration, an overview of the most important
currently defined settings is provided in the "Overview". The "Overview" is displayed
when you select the "Overview" icon, which is available at the bottom of all softkey
menus.
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Configuration
Configuration overview
In addition to the main measurement settings, the "Overview" provides quick access to
the main settings dialog boxes. The individual configuration steps are displayed in the
order of the data flow. Thus, you can easily configure an entire measurement channel
from input over processing to output and analysis by stepping through the dialog boxes
as indicated in the "Overview".
In particular, the "Overview" provides quick access to the following configuration dialog
boxes (listed in the recommended order of processing):
To perform a calibration
1. Noise Source
See Chapter 5.4, "Configuring the noise source", on page 50.
2. Calibration Loss
See Chapter 5.5, "Configuring additional loss", on page 58
3. Spectrum Analyzer
See Chapter 5.6, "Configuring the analyzer", on page 63.
4. Calibration
See "Calibrate" on page 82
To perform a measurement
1. Noise Source
See Chapter 5.4, "Configuring the noise source", on page 50.
2. Input and output losses
See Chapter 5.5, "Configuring additional loss", on page 58.
3. DUT configuration
See Chapter 5.3, "Selecting DUT characteristics", on page 49
4. Spectrum Analyzer
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Configuration
Defining the measurement frequency
See Chapter 5.6, "Configuring the analyzer", on page 63.
5. Display Configuration
See Chapter 6.1, "Configuring the display", on page 90
To configure settings
► Select any button in the "Overview" to open the corresponding dialog box.
Select a setting in the channel bar (at the top of the measurement channel tab) to
change a specific setting.
Preset Channel
Select the "Preset Channel" button in the lower left-hand corner of the "Overview" to
restore all measurement settings in the current channel to their default values.
Note: Do not confuse the "Preset Channel" button with the [Preset] key, which restores
the entire instrument to its default values and thus closes all channels on the
R&S FSW (except for the default channel)!
Remote command:
SYSTem:PRESet:CHANnel[:EXEC] on page 116
Specific Settings for
The channel can contain several windows for different results. Thus, the settings indicated in the "Overview" and configured in the dialog boxes vary depending on the
selected window.
Select an active window from the "Specific Settings for" selection list that is displayed
in the "Overview" and in all window-specific configuration dialog boxes.
The "Overview" and dialog boxes are updated to indicate the settings for the selected
window.
5.2 Defining the measurement frequency
● Defining a frequency set......................................................................................... 42
● Configuring single frequency measurements..........................................................45
● Using a frequency table.......................................................................................... 46
5.2.1 Defining a frequency set
Access: "Overview" > "DUT" > "Frequency Config"
These settings define the frequency characteristics for the measurement.
The information in this tab is also the basis for an automatic population of the frequency table. All parameters of this dialog are interdependent. If you change one
parameter, at least one other parameter is changed by the application.
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Configuration
Defining the measurement frequency
If you change a frequency set, perform a new calibration to ensure accurate results.
Preamplifier
If a preamplifier is used, make sure the defined (and possibly upconverted) IF frequencies for the measurement stay below the maximum frequency the preamplifier supports. For the R&S FSW-B22 option, the maximum frequency is 7 GHz. However, the
preamplifier can be activated or deactivated individually for different tuning modes. For
example, for a sweep mode which requires a span above 7 GHz it is deactivated, while
for a single frequency measurement at 1 GHz it can be activated.
Tuning Mode................................................................................................................. 43
Center........................................................................................................................... 44
Span..............................................................................................................................44
Start and Stop Frequency............................................................................................. 44
(Measurement) Points...................................................................................................45
Step...............................................................................................................................45
Tuning Mode
Selects the tuning or measurement mode.
For more information, see Chapter 4.1, "Tuning modes", on page 22.
Tuning mode selection is also available via softkeys ("Sweep Mode", "Frequency Table
Mode", "Single Frequency Mode") in the "Sweep" menu.
Note: A preamplifier can be activated or deactivated individually for different tuning
modes. When you switch tuning modes, the defined preamplifier state is adapted.
"Sweep"
The measurement is based on an automatically generated frequency
set.
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Configuration
Defining the measurement frequency
"Frequency
Table"
"Single Frequency"
Remote command:
Frequency sweep measurement:
[SENSe:]CONFigure:LIST:CONTinuous on page 126
[SENSe:]CONFigure:LIST:SINGle on page 126
INITiate<n>[:IMMediate] on page 179
Single frequency measurement:
[SENSe:]CONFigure:FREQuency:CONTinuous on page 125
[SENSe:]CONFigure:FREQuency:SINGle on page 126
INITiate<n>[:IMMediate] on page 179
Center
Defines the center of the measurement frequency range.
If you change the center frequency, the application changes the start and stop fre-
quency according to the span you have set.
The "Center" setting is also available via the [FREQ] key.
Remote command:
Frequency list measurement:
[SENSe:]FREQuency:CENTer on page 127
Single frequency measurement:
[SENSe:]FREQuency:SINGle on page 128
The measurement is based on a customized frequency table.
For more information, see Chapter 5.2.3, "Using a frequency table",
on page 46.
The measurement measures a single frequency only.
For more information, see Chapter 5.2.2, "Configuring single fre-
quency measurements", on page 45.
Span
Defines the measurement span.
If you change the span, the application changes the start frequency, the stop frequency
and the stepsize according to the center frequency and the measurement points.
The "Span" setting is also available via the [SPAN] key.
Remote command:
[SENSe:]FREQuency:SPAN on page 129
Start and Stop Frequency
Defines the start and stop frequencies.
If you change the start or stop frequency, the application changes the center frequency,
the span and the measurement points according to the new values and the stepsize.
The "Start" and "Stop" settings are also available via the [FREQ] key.
Remote command:
Start frequency:
[SENSe:]FREQuency:STARt on page 129
Stop frequency:
[SENSe:]FREQuency:STOP on page 130
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Configuration
Defining the measurement frequency
(Measurement) Points
Defines the measurement points.
For frequency list measurements, the number of measurement points corresponds to
the number of entries in the frequency table. The number of points displayed in the
graphical results is also the same.
If you change the measurement points, the application changes the stepsize according
to the span.
The "Points" setting is also available via the [SPAN] key.
Remote command:
[SENSe:]FREQuency:POINts on page 128
Step
Defines the frequency step size in the frequency table.
The stepsize corresponds to the distance between two consecutive measurement
points.
If you change the stepsize, the application changes the measurement point according
to the span.
The "Stepsize" setting is also available via the [FREQ] key.
Remote command:
[SENSe:]FREQuency:STEP on page 129
5.2.2 Configuring single frequency measurements
Access: "Overview" > "DUT" > "Frequency Config" > "Tuning Mode: Single Fre-
quency"
These settings define the frequency characteristics for the measurement.
If you change the frequency, perform a new calibration to ensure accurate results.
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Configuration
Defining the measurement frequency
Single (Frequency)........................................................................................................46
Coupled to Sweep List.................................................................................................. 46
(Measurement) Points...................................................................................................46
Single (Frequency)
Defines the frequency that the single frequency measurement is performed on.
The "Single" setting is also available via the [FREQ] key.
Remote command:
[SENSe:]FREQuency:SINGle on page 128
Coupled to Sweep List
Couples or decouples frequency selection to the contents of a sweep list.
If you couple the frequency to the sweep list, the application allows you to select only
the frequencies currently part of the frequency list. If you enter another frequency, the
application automatically selects the nearest frequency of the frequency list. If the frequency list has been calibrated previously, calibration remains valid for those frequencies when you change the tuning mode.
If you turn off the coupling, you can define any frequency for single frequency measurements. Note, however, that you have to calibrate the measurement for that frequency.
Remote command:
[SENSe:]FREQuency:SINGle:COUPled on page 129
(Measurement) Points
Defines the number of measurement points for single frequency measurements.
For single frequency measurements, the number of measurement points corresponds
to the number of measurements (index values) performed on a single frequency.
For more information, see "Single frequency measurements" on page 14.
The "Points" setting is also available via the [SPAN] key.
Remote command:
[SENSe:]FREQuency:POINts on page 128
5.2.3 Using a frequency table
Access: "Overview" > "DUT" > "Frequency Config" > " Frequency Table"
The "Frequency Table" tab in the "Frequency Settings" dialog box contains functionality
to manage the measurement frequencies.
The application populates the table according to the information you entered in the
"Frequency Config" tab when you select "Populate Table".
Note that changes to the frequency table take effect only if you select the "Frequency
Table" tuning mode.
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Configuration
Defining the measurement frequency
Frequency Table............................................................................................................47
Clear Table....................................................................................................................48
Populate Table.............................................................................................................. 48
Insert............................................................................................................................. 48
Delete............................................................................................................................48
Import / Export...............................................................................................................48
Frequency Table
Shows the current measurement points.
The table is made up of one column that represents the measurement frequency. Each
frequency corresponds to one measurement point. The length of the table is variable
(up to a maximum of 10001 points).
When you perform measurements in "Sweep" or "Single Frequency" tuning mode, the
contents of the table have no effect on the measurement.
When you select a table entry in "Frequency Table" tuning mode, you can edit it or add
a new frequency below the selected frequency. A new frequency has to be higher than
the last table entry and lower than the next table entry.
If the RBW and sweep time settings are set to "variable" in the measurement settings
(see Resolution Bandwidth (RBW) and "Sweep Time" on page 64), you can also
define those values in the frequency table.
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Configuration
Defining the measurement frequency
Select Populate Table to predefine the RBW and sweep times to be used. For each
sweep point with a frequency under 10 MHz in the table, suitable settings are defined.
For higher frequencies, the values provided in the measurement settings are used
(indicated by "--" as they are automatically updated if the measurement settings
change.) All predefined values in the table can be overwritten manually.
The defined RBW and sweep times are also included in a table export.
See also "Variable RBW and sweep time for low-frequency measurements"
on page 36.
Clear Table
Deletes the contents of the table.
Populate Table
Populates or restores the measurement frequencies based on the center frequency,
the start and stop frequencies, the span, the stepsize and the number of measurement
points.
If the RBW and sweep time settings are set to "variable" in the measurement settings
(see Resolution Bandwidth (RBW) and "Sweep Time" on page 64), those values are
also predefined. For each sweep point with a frequency under 10 MHz in the table,
suitable settings are defined. For higher frequencies, the values provided in the measurement settings are used (indicated by "--" as they are automatically updated if the
measurement settings change.) All predefined values in the table can be overwritten
manually.
See also "Variable RBW and sweep time for low-frequency measurements"
on page 36.
Remote command:
[SENSe:]FREQuency:TABLe:DATA on page 127
[SENSe:]FREQuency:LIST:DATA on page 127
RBW and sweep time set to variable: [SENSe:]BANDwidth:LIST:DATA
on page 128
Insert
Inserts a new measurement point above the one you have selected.
Delete
Deletes the currently selected measurement point.
Import / Export
Opens a dialog box to select a frequency table to import or export.
An import copies the frequency table into the default frequency table directory. An
export copies the table to a location outside the default frequency table directory, e.g. a
memory stick. The file extension has to be *.freq.
If variable RBW and sweep times are enabled, they are also included in a table export
(see "Frequency Table" on page 47).
For details on the required file format, see Chapter A, "Reference: frequency table file
format", on page 237.
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5.3 Selecting DUT characteristics
Configuration
Selecting DUT characteristics
Access: "Overview" > "DUT" > "DUT Settings"
The "DUT" button opens a dialog box to configure the characteristics of the DUT you
are testing. The dialog box contains a schematic overview of the DUT input and output
characteristics and the way it is integrated into the test setup.
Mode
............................................................................................................................. 49
LO Fixed........................................................................................................................49
IF Fixed......................................................................................................................... 50
Image Rejection............................................................................................................ 50
Mode
Selects the measurement mode.
The required measurement mode depends on the type of DUT you are testing. For
more information, see Chapter 4.3, "DUT types", on page 26.
Note: For upconverting measurements, if a preamplifier is used, make sure the upcon-
verted frequencies for the measurement stay below the maximum frequency the preamplifier supports.
Remote command:
DUT type: [SENSe:]CONFigure:MODE:DUT on page 131
LO type: [SENSe:]CONFigure:MODE:SYSTem:LO on page 131
LO Fixed
Defines a fixed LO frequency for measurements on frequency-converting DUTs with a
fixed LO.
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Configuration
Configuring the noise source
After you have defined the LO frequency, the application updates the frequency list
accordingly.
The "LO" setting is also available via the [FREQ] key.
Remote command:
[SENSe:]CONFigure:MODE:SYSTem:LO:FREQuency on page 131
IF Fixed
Defines a fixed intermediary frequency (IF) for measurements on frequency-converting
DUTs with a fixed IF.
After you have defined the intermediary frequency, the application updates the frequency list accordingly.
The "IF" setting is also available via the [FREQ] key.
Remote command:
[SENSe:]CONFigure:MODE:SYSTem:IF:FREQuency on page 130
Image Rejection
Turns image rejection of the DUT on and off.
If you set an image rejection of 0 dB, the image frequency passes completely. If you
set a high image rejection (up to 999.99 dB), the image frequency is suppressed completely. For DUTs that have a partial image rejection, define the amount of suppression.
For more information, see Chapter 4.5, "Image frequency rejection", on page 29.
Remote command:
[SENSe:]CORRection:IREJection on page 132
5.4 Configuring the noise source
The noise source characteristics are used to calculate the effective "noise temperature"
of the noise source. The more accurate the specified characteristics of the noise
source you are using, the more accurate the measurement results. The noise source
characteristics must be supplied by its manufacturer.
● Defining the noise source characteristics................................................................50
● Using an ENR or temperature table........................................................................54
5.4.1 Defining the noise source characteristics
Access: "Overview" > "Noise Source" > "ENR / Temp Settings"
The noise characteristics of noise sources with diode characteristics are usually
defined by their ENR (Excess Noise Ratio). The noise characteristics of noise sources
with resistor characteristics are defined by their noise (or ambient) temperatures (T
and T
Both noise source types can have different ENR values during the calibration and the
measurement stage. You can use either the same type of noise source for both calibra-
cold
). T
is typically at a very low temperature of liquid nitrogen or liquid helium.
cold
hot
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Configuration
Configuring the noise source
tion and measurement, or use different types of noise sources for calibration and measurement.
Auto Select SNS........................................................................................................... 51
Noise Source.................................................................................................................52
Measurement................................................................................................................ 52
Common Noise Source.................................................................................................53
Calibration.....................................................................................................................53
Temperature..................................................................................................................54
Auto Select SNS
If enabled (default), the R&S FSW Noise measurements application automatically recognizes a connected smart noise source and uses it for the noise measurement. The
provided ENR and uncertainty tables and temperature are loaded and used for the
measurement. The recognized serial number of the SNS is indicated in the channel bar
and dialogs of the R&S FSW Noise measurements application.
If "Auto Select SNS" is ON and a SNS is connected, a green message with information
about the connected SNS is displayed:
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Configuration
Configuring the noise source
If no SNS is connected, a red "No SNS connected" warning is displayed:
If "Auto Select SNS" is disabled, you must manually change the noise source to SNS
and select the required tables, if necessary (see "Frequency Table" on page 47).
Noise Source
Access: "Overview" > "Noise Source" > "ENR / Temp Settings" > "Noise Source"
You can select the type of noise source and its characteristics independently for the
Calibration and the Measurement.
"Diode"
Selects a noise source with diode characteristics. The frequency
characteristics of the noise source are defined by the Excess Noise
ratio (ENR).
"Resistor"
Selects a test setup that uses two resistors which act as a noise
source. One of the resistors has a low noise or ambient temperature
(a cold resistor), the other has a high noise or ambient temperature (a
hot resistor). The noise characteristics of the resistor are defined by
its "noise temperatures" T
and T
hot
cold
.
When you select the resistor noise source, the application automatically starts the manual measurement mode, which is indicated in a
message at the bottom of the dialog box.
"Smart Noise
Source"
Selects a smart noise source, which provides its own ENR and uncertainty tables. The serial number of the connected noise source is
automatically recognized and indicated. Otherwise, enter the number
of a noise source to continue preconfiguring the measurement.
Remote command:
Measurement: [SENSe:]CORRection:ENR[:MEASurement]:TYPE on page 138
[SENSe:]CORRection:ENR[:MEASurement]:SNS:SRNumber on page 140
Calibration: [SENSe:]CORRection:ENR:CALibration:TYPE on page 135
[SENSe:]CORRection:ENR:CALibration:SNS:SRNumber on page 140
Measurement
Selects the source of the ENR or temperature values.
The frequency characteristics can be approximated by a constant or be based on an
ENR or temperature table.
If the ENR or temperature is a constant, the same values are used for all frequencies
in the frequency table. If you have selected a constant ENR, you have to define its
magnitude in the input field next to the radio button. If you have selected a constant
temperature, you have to define the temperatures of the resistor in the input fields next
to the radio button. T
temperature; T
cold
is the temperature of a resistor with a low noise or ambient
hot
is the temperature of a resistor with a high noise or ambient temper-
ature.
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Configuration
Configuring the noise source
If the noise characteristics are based on a table, the ENR level and temperatures typically depend on the measurement frequency. You can select an existing table from the
dropdown menu next to the radio button, if it is active. For more information on ENR
and temperature tables, see Chapter 5.4.2, "Using an ENR or temperature table",
on page 54.
When "Common Noise Source" is on, the ENR is used for both measurement and calibration.
Remote command:
ENR mode: [SENSe:]CORRection:ENR[:MEASurement]:MODE on page 137
Constant ENR: [SENSe:]CORRection:ENR[:MEASurement]:SPOT on page 138
Select table:[SENSe:]CORRection:ENR[:MEASurement]:TABLe:SELect
on page 136
Constant temperature: [SENSe:]CORRection:ENR[:MEASurement]:SPOT:COLD
on page 139
Constant temperature: [SENSe:]CORRection:ENR[:MEASurement]:SPOT:HOT
on page 139
Common Noise Source
Turns the use of a common ENR on and off.
Common ENRs have the same characteristics for the measurement and calibration. If
you turn off common ENR, you can define an additional ENR to be used during calibration.
Define additional ENR for measurements on frequency converting DUTs, if one noise
source does not cover the frequency range at the DUT input (RF) and for calibration
(IF).
Remote command:
[SENSe:]CORRection:ENR:COMMon on page 135
Calibration
Selects the source of the ENR or temperature values used during calibration.
The frequency characteristics can be a constant or be based on an ENR or tempera-
ture table.
If the ENR or temperature is a constant, the same value is used for all frequencies in
the frequency table. If you have selected a constant ENR, you can also define its value
in the input field next to the radio button. If you have selected a constant temperature,
you have to define the temperatures of the resistor in the input fields next to the radio
button. T
T
is the temperature of a resistor with a high noise or ambient temperature.
cold
is the temperature of a resistor with a low noise or ambient temperature;
hot
If the noise source characteristics are based on a table, the ENR level and temperature
depend on the measurement frequency. In that case, the values are interpolated to the
measurement points. You can select a table from the dropdown menu next to the radio
button, if it is active. For more information on ENR tables, see Chapter 5.4.2, "Using an
ENR or temperature table", on page 54.
The calibration settings are available if the "Common Noise Source" is off.
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Configuration
Configuring the noise source
Remote command:
ENR mode:[SENSe:]CORRection:ENR:CALibration:MODE on page 133
Constant ENR: [SENSe:]CORRection:ENR:CALibration:SPOT on page 134
Select table: [SENSe:]CORRection:ENR:CALibration:TABLe:SELect
on page 134
Constant temperature: [SENSe:]CORRection:ENR:CALibration:SPOT:COLD
on page 133
Constant temperature: [SENSe:]CORRection:ENR:CALibration:SPOT:HOT
on page 133
Temperature
Defines the absolute room temperature in degree Celsius or Fahrenheit.
The room temperature is required for the calculation of the real ENR of the noise
source, because an ENR table is based on a temperature of 290K.
For smart noise sources, the temperature is provided automatically by the connected
SNS itself. If no SNS is connected, the most recently loaded value is indicated. The
provided temperature is used for all noise sources throughout the measurement.
To set the temperature manually, select "Manual" and enter the value.
To change the unit of the temperature from Celsius to Fahrenheit, change the date for-
mat from "DE" to "US" in the "General" display settings.
●
Press the [SETUP] key.
●
Select "Display".
●
Select the "General" tab.
●
Select "DE" for Celsius or "US" for Fahrenheit.
Note: If you define the temperature via remote control, the unit is degree Kelvin.
Remote command:
[SENSe:]CORRection:TEMPerature on page 139
5.4.2 Using an ENR or temperature table
Access: "Overview" > "Noise Source" > "Table Settings"
The "Table Settings" tab in the "ENR/TEMP Settings" dialog box contains the functionality to create and edit ENR or temperature tables.
ENR or temperature tables contain the noise source characteristics for particular frequencies. If the table does not contain ENR or temperature values for one of the measurement frequencies, the application interpolates between the values.
The "Table Settings" tab contains a list of ENR and temperature tables currently available on the R&S FSW and shows the table currently in use if the "ENR/TEMP Settings"
are enabled.
In addition, the tab contains functionality to create new tables and modify existing
ones.
Noise Source.................................................................................................................55
New...............................................................................................................................55
Edit................................................................................................................................55
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Configuration
Configuring the noise source
Delete............................................................................................................................56
Copy To.........................................................................................................................56
Import / Export Table.....................................................................................................56
Edit Table...................................................................................................................... 56
Noise Source
Selects the type of noise source you are using for the measurement. The type of noise
source selected in the "ENR/TEMP Settings" > "Noise Source" dialog is adopted automatically.
The noise source type affects the data type that the table contains. For a "Noise
Diode", the table contains the ENR values of the noise source you are using. For a
"Resistor", the table contains the "noise temperatures" of the resistors (T
and T
hot
cold
).
For a smart noise source, the table contains the provided ENR and uncertainty table.
The table for the connected noise source is automatically recognized and highlighted.
The name of the ENR table contains the serial number of the SNS. The "default" table
also contains the data for the most recently connected smart noise source. The tables
for all previously connected noise sources, whose ENR tables remain stored on the
instrument, are also listed. Smart noise source tables are for reference only and cannot
be edited.
For more information on the noise source types, see "Noise Source" on page 52.
Remote command:
[SENSe:]CORRection:ENR[:MEASurement]:TYPE on page 138
New
Opens the Edit Table dialog box to create a new table.
The contents of the dialog box are empty.
Smart noise source tables are shown for reference only and cannot be edited. A mes-
sage indicates whether the SNS with the selected serial number is currently connected
to the R&S FSW or not. If it is connected, the table data reflects the most recent data
provided by the SNS.
Remote command:
Table selection: [SENSe:]CORRection:ENR:CALibration:TABLe:SELect
on page 134
and:[SENSe:]CORRection:ENR[:MEASurement]:TABLe:SELect on page 136
Diode: [SENSe:]CORRection:ENR[:MEASurement]:TABLe[:DATA] on page 135
Resistor: [SENSe:]CORRection:ENR[:MEASurement]:TABLe:TEMPerature[:
DATA] on page 137
Edit
Opens the Edit Table dialog box to modify the selected table.
Smart noise source tables are for reference only and cannot be edited.
Remote command:
Table selection: [SENSe:]CORRection:ENR[:MEASurement]:TABLe:SELect
on page 136
and: [SENSe:]CORRection:ENR[:MEASurement]:TABLe:SELect on page 136
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Configuration
Configuring the noise source
Diode: [SENSe:]CORRection:ENR[:MEASurement]:TABLe[:DATA] on page 135
Resistor: [SENSe:]CORRection:ENR[:MEASurement]:TABLe:TEMPerature[:
DATA] on page 137
Delete
Deletes the selected table.
Smart noise source tables cannot be deleted.
Remote command:
Diode: [SENSe:]CORRection:ENR[:MEASurement]:TABLe:DELete on page 136
Resistor:[SENSe:]CORRection:ENR[:MEASurement]:TABLe:TEMPerature:
DELete on page 137
Copy To
Opens the Edit Table dialog box to modify the selected table and save it under a new
name.
Import / Export Table
Opens a dialog box to select a table to import or export.
Smart noise source tables can be exported, but not re-imported. Tables for smart noise
sources are always loaded directly from the SNS itself. However, you can edit and use
the SNS tables for other noise sources, such as noise diodes.
Edit Table
Defines the noise source characteristics or the loss characteristics of additional measurement equipment.
The noise source and loss tables are made up of up to 10001 data points. A data point
consists of a frequency and its corresponding ENR, temperature or loss value. The
ENR and temperature values must be supplied by the manufacturer of the noise
source or resistor. The loss characteristics of measurement equipment must also be
supplied by the manufacturer.
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Configuration
Configuring the noise source
"Name"
"Comment"
"Frequency"
"Value"
Name of the ENR, temperature or loss table.
Comment for the ENR, temperature or loss table.
Frequency of a particular ENR, temperature or loss value.
ENR value or loss in dB.
For a resistor, the characteristics of the resistor are defined by the
"noise temperatures" T
and T
hot
instead of a single value. The unit
cold
in that case is Kelvin (degrees).
"Clear Table"
Deletes the contents of the table (frequencies and values) or the loss
table.
"Insert"
"Delete"
"Save"
"Cancel"
Inserts a new data point above the selected one.
Deletes the selected data point.
Saves the able.
Exits the "Edit Table" dialog box and returns to the result diagram.
Remote command:
Edit ENR table: [SENSe:]CORRection:ENR[:MEASurement]:TABLe[:DATA]
on page 135
Edit temperature table: [SENSe:]CORRection:ENR[:MEASurement]:TABLe:
TEMPerature[:DATA] on page 137
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5.5 Configuring additional loss
Configuration
Configuring additional loss
Edit input loss table: [SENSe:]CORRection:LOSS:INPut:TABLe[:DATA]
on page 143
Edit output loss table: [SENSe:]CORRection:LOSS:OUTPut:TABLe[:DATA]
on page 145
These settings configure the loss characteristics of additional equipment in the test
setup, such as cables or attenuators at the DUT input or output. The characteristics of
such equipment must be supplied by the manufacturer.
Note that loss is only considered during the measurement and not during calibration
because the noise source is connected directly to the analyzer input.
Treatment of losses in resistor noise sources
For resistor noise sources, it is not possible to change the loss characteristics.
When you change back to using a diode as a noise source, the previous loss settings
are not restored. In that case, store loss settings in a loss table for later use.
● Defining loss............................................................................................................58
● Using a loss table....................................................................................................61
5.5.1 Defining loss
Access: "Overview" > "Loss Input" / "Loss Output" > "Loss Settings"
The "Loss Settings" tab in the "Loss Settings" dialog box contains settings to define the
loss characteristics of miscellaneous equipment in the test setup.
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Configuration
Configuring additional loss
You can define the loss characteristics of the signal path to the DUT input and the signal path from the DUT output to the analyzer.
Furthermore, you can define the loss characteristics of the signal path from the noise
source directly to the analyzer for the calibration measurement.
Input Loss......................................................................................................................59
Output Loss...................................................................................................................60
Calibration Loss............................................................................................................ 60
Input Loss
Defines losses between the noise source and the DUT input.
The input loss is the sum of all losses caused by the measurement equipment. The
loss can be constant or based on a loss table.
If the loss is constant, the same loss is used for all frequencies in the frequency table.
If you have selected a constant loss, you can also define its value in the input field next
to the radio button.
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Configuration
Configuring additional loss
If the loss is based on a table, the loss values are interpolated to the measurement frequencies. You can select a table from the dropdown menu next to the radio button, if it
is active. For more information on loss tables, see Chapter 5.5.2, "Using a loss table",
on page 61.
The specified temperature at the time of measurement can be considered in the loss
calculation.
Remote command:
Loss mode:
[SENSe:]CORRection:LOSS:INPut:MODE on page 143
Constant loss:
[SENSe:]CORRection:LOSS:INPut:SPOT on page 143
Select loss table:
[SENSe:]CORRection:LOSS:INPut:TABLe:SELect on page 144
Temperature:
[SENSe:]CORRection:LOSS:INPut:TEMPerature on page 145
Output Loss
Selects the loss between the DUT output and the RF input of the analyzer.
The output loss is the sum of all losses caused by the measurement equipment (e.g.
connectors, cables or attenuators). The loss can be constant or be based on a loss
table.
If the loss is constant, the same loss is used for all frequencies in the frequency table.
If you have selected a constant loss, you can also define its value in the input field next
to the radio button.
If the loss is based on a table, the loss values are interpolated to the measurement frequencies. You can select a table from the dropdown menu next to the radio button, if it
is active. For more information on loss tables, see Chapter 5.5.2, "Using a loss table",
on page 61.
The current temperature at the time of measurement can be considered in the loss calculation.
Remote command:
Loss mode:
[SENSe:]CORRection:LOSS:OUTPut:MODE on page 145
Constant loss:
[SENSe:]CORRection:LOSS:OUTPut:SPOT on page 145
Select loss table:
[SENSe:]CORRection:LOSS:OUTPut:TABLe:SELect on page 146
Temperature:
[SENSe:]CORRection:LOSS:OUTPut:TEMPerature on page 146
Calibration Loss
Selects the loss between the noise source and the RF input of the analyzer for the calibration measurement.
The loss is the sum of all losses caused by the measurement equipment (e.g. connectors, cables or attenuators). The loss can be constant or be based on a loss table.
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Configuration
Configuring additional loss
If the loss is constant, the same loss is used for all frequencies in the frequency table.
If you have selected a constant loss, you can also define its value in the input field next
to the radio button.
If the loss is based on a table, the loss values are interpolated to the measurement frequencies. You can select a table from the dropdown menu next to the radio button, if it
is active. For more information on loss tables, see Chapter 5.5.2, "Using a loss table",
on page 61.
The current temperature at the time of measurement can be considered in the loss calculation.
Remote command:
Loss mode:
[SENSe:]CORRection:LOSS:CALibration:MODE on page 141
Constant loss:
[SENSe:]CORRection:LOSS:CALibration:SPOT on page 141
Select loss table:
[SENSe:]CORRection:LOSS:CALibration:TABLe:SELect on page 142
Temperature:
[SENSe:]CORRection:LOSS:CALibration:TEMPerature on page 142
5.5.2 Using a loss table
Access: "Overview" > "Loss Input" / "Loss Output" > "Table Settings"
The "Table Settings" tab in the "Loss Settings" dialog box contains the functionality to
create and edit loss tables.
Loss tables contain the loss characteristics of additional frequency-dependent equipment in the test setup. If you are using a loss table, the loss values can be different on
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Configuration
Configuring additional loss
each frequency that is measured. If the table does not contain a loss for one of the
measurement frequencies, the application interpolates between values.
The "Table Settings" tab contains a list of loss tables currently available on the
R&S FSW. It shows the table currently selected in the "Loss Settings" tab.
In addition, the tab contains functionality to create new tables and modify existing
ones.
New...............................................................................................................................62
Edit................................................................................................................................62
Delete............................................................................................................................62
Copy To.........................................................................................................................62
Import / Export Table.....................................................................................................63
New
Opens the Edit Table dialog box to create a new loss table.
The contents of the dialog box are empty.
Remote command:
Create input loss table:
[SENSe:]CORRection:LOSS:INPut:TABLe[:DATA] on page 143
Create output loss table:
[SENSe:]CORRection:LOSS:OUTPut:TABLe[:DATA] on page 145
Create calibration loss table:
[SENSe:]CORRection:LOSS:CALibration:TABLe[:DATA] on page 142
Edit
Opens the Edit Table dialog box to modify the selected table.
Remote command:
Edit input loss table:
[SENSe:]CORRection:LOSS:INPut:TABLe[:DATA] on page 143
Edit output loss table:
[SENSe:]CORRection:LOSS:OUTPut:TABLe[:DATA] on page 145
Edit calibration loss table:
[SENSe:]CORRection:LOSS:CALibration:TABLe[:DATA] on page 142
Delete
Deletes the selected table.
Remote command:
Delete input loss table:
[SENSe:]CORRection:LOSS:INPut:TABLe:DELete on page 144
Delete output loss table:
[SENSe:]CORRection:LOSS:OUTPut:TABLe:DELete on page 146
Delete calibration loss table:
[SENSe:]CORRection:LOSS:CALibration:TABLe:DELete on page 141
Copy To
Opens the Edit Table dialog box to modify the selected table and save it under a new
name.
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5.6 Configuring the analyzer
Configuration
Configuring the analyzer
Import / Export Table
Opens a dialog box to select a loss table to import or export.
An import copies the loss table into the default loss table directory. The file extension
can be *.loss or *.s2p. In case the file extension is *.s2p, the S21 vector is parsed
out of the *.s2p file. The magnitude of this vector is written to a file with ending
*.loss into the default loss directory. This file then can be used like conventional loss
files.
An export copies the table to a location outside the default loss table directory, e.g. a
memory stick. The file extension will be *.loss.
Access: "Overview" > "Spectrum Analyzer"
Or: [MEAS CONFIG] > "Meas Settings"
The measurement settings include parameters related to the second stage correction
measurement.
2nd Stage Correction.................................................................................................... 64
Resolution Bandwidth (RBW)........................................................................................64
Sweep Time.................................................................................................................. 64
Settling Time................................................................................................................. 65
Average.........................................................................................................................65
Ref Level.......................................................................................................................65
Auto Level Range..........................................................................................................66
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Configuration
Configuring the analyzer
RF Attenuation.............................................................................................................. 66
Preamplifier...................................................................................................................66
Ext. PA Correction.........................................................................................................67
2nd Stage Correction
Turns 2nd stage correction on and off.
If enabled, the application uses the calibration data to compensate for the inherent
noise of the analyzer when calculating the measurement results.
If disabled, the application does not correct the measurement results, even if a valid
calibration has been performed. Note that correction data is not deleted if you turn off
the 2nd stage correction.
For more information, see Chapter 4.6, "Calibration (2nd stage correction)",
on page 32.
Remote command:
State: [SENSe:]CORRection[:STATe] on page 149
Calibration measurement selection:[SENSe:]CONFigure:CORRection on page 148
Resolution Bandwidth (RBW)
Defines the resolution bandwidth for the measurement.
For more information on the resolution bandwidth, see Chapter 4.8, "Separating sig-
nals by selecting an appropriate resolution bandwidth", on page 35.
"Constant"
"Variable"
Remote command:
[SENSe:]BANDwidth:RESolution:AUTO on page 148
[SENSe:]BANDwidth[:RESolution] on page 147
Uses a constant RBW for the entire measurement span
Uses a variable RBW, depending on the current frequency of the
sweep point, as defined in the frequency table (see Chapter 5.2.3,
"Using a frequency table", on page 46);
In the channel bar, the bandwidth and sweep time range of the vari-
able values is indicated.
Sweep Time
Defines the sweep time for the measurement.
The sweep time is the time it takes the analyzer to perform a measurement at one
measurement frequency.
Note that "noise figure" measurements perform two measurements during one sweep.
One with the noise source turned on, one with the noise source turned off.
Frequency tables allow you to define a variable RBW and sweep time, depending on
the current frequency of the sweep point (see "Variable RBW and sweep time for low-
frequency measurements" on page 36 and Chapter 5.2.3, "Using a frequency table",
on page 46).
"Constant"
Uses a constant sweep time for the entire measurement span
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Configuration
Configuring the analyzer
"Variable"
Remote command:
[SENSe:]SWEep:TIME:AUTO on page 150
[SENSe:]SWEep:TIME on page 150
Settling Time
Defines the settling time of the DUT and the noise source.
Most noise sources need a certain amount of time to settle after you turn them on.
Low-frequency DUTs can require a certain time until their coupling capacitors have
been charged or discharged. Both are defined as the settling time. For details on the
settling time, refer to the datasheet of the noise source.
Remote command:
SYSTem:CONFigure:DUT:STIMe on page 154
Average
Defines the number of measurements that are used to average the results.
The more measurements you include in the averaging, the more accurate and stable
the results are. However, accuracy and stability come at the price of measurement
speed.
Remote command:
[SENSe:]SWEep:COUNt on page 150
Uses a variable sweep time, depending on the current frequency of
the sweep point, as defined in the frequency table (see Chapter 5.2.3,
"Using a frequency table", on page 46);
In the channel bar, the bandwidth and sweep time range of the vari-
able values is indicated.
Ref Level
Turns automatic determination of the reference level on and off.
The reference level is the power level the R&S FSW expects at the RF input. Keep in
mind that the noise signal has a high crest factor. To avoid an instrument overload, set
the reference level to the peak envelope power of the noise signal, not to the mean
power.
Set the reference level to approximately 5 dB to 15 dB above the noise display that
occurs with the DUT connected and the noise source activated.
To get the best dynamic range, set the reference level as low as possible. At the same
time, make sure that the maximum signal level does not exceed the reference level. If
it does, it can overload the RF and IF stages of the analyzer, regardless of the signal
power. Measurement results can deteriorate.
Note that the signal level at the A/D converter can be stronger than the level the
R&S FSW displays because the resolution bandwidths are implemented digitally after
the A/D converter.
If automatic detection of the reference level is on, the application performs a measurement to determine the ideal reference level. The time of this measurement depends on
the state of the "2nd Stage Correction".
●
"2nd Stage Correction" is enabled
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Configuration
Configuring the analyzer
The application determines the reference level before the calibration starts. The
reference level is based on several test measurements on the start frequency.
For more information, see "Auto Level Range" on page 66.
●
"2nd Stage Correction" is disabled
The application determines the reference level before the measurement begins.
The reference level is based on the measurement of the first frequency that is
measured. After this measurement is done, the application resumes the measurement.
If manual selection of the reference level is on, you can define the reference level in
the corresponding input field.
Note: Reference level. Even for DUTs with a high-ripple frequency response it can be
useful to define the reference level manually. Determining the reference level automatically does not always result in optimal settings.
Remote command:
Manual reference level:
DISPlay[:WINDow<n>]:TRACe<t>:Y[:SCALe]:RLEVel on page 151
Automatic reference level:
DISPlay[:WINDow<n>]:TRACe<t>:Y[:SCALe]:RLEVel:AUTO on page 151
Auto Level Range
Defines the maximum expected "gain" of the DUT.
The application uses the auto level range to determine the reference level automati-
cally if the 2nd stage correction is on.
Make sure the range does not exceed the actual "gain" of the DUT by more than
10 dB.
Remote command:
SYSTem:CONFigure:DUT:GAIN on page 153
RF Attenuation
Defines the RF attenuation of the analyzer.
The attenuation is applied to the signal at the RF input.
Attenuation affects the quality of the "noise figure" measurement results. For a low
"noise figure" of the analyzer (and thus more accurate measurement results), keep the
attenuation as low as possible. No attenuation is best. However, some high-power
DUTs require attenuation to avoid an overload of the analyzer. An attenuation of 10 dB
provides a better input VSWR of the analyzer, but results in a deteriorating "noise figure".
Remote command:
INPut<ip>:ATTenuation on page 151
Preamplifier
If the (optional) internal preamplifier hardware is installed, a preamplifier can be activated for the RF input signal.
Turn on the preamplifier for a low inherent noise of the analyzer.
Note: If an optional external preamplifier is activated, the internal preamplifier is auto-
matically disabled, and vice versa.
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Configuration
Using the uncertainty calculator
For an active external frontend, a preamplifier is not available.
For all R&S FSW models except for R&S FSW85, the following settings are available:
"Off"
"15 dB"
"30 dB"
For R&S FSW85 models, the input signal is amplified by 30 dB if the preamplifier is
activated.
Remote command:
INPut<ip>:GAIN:STATe on page 152
INPut<ip>:GAIN[:VALue] on page 153
Ext. PA Correction
This function is only available if an external preamplifier is connected to the R&S FSW,
and only for frequencies above 1 GHz. For details on connection, see the preamplifier's
documentation.
Using an external preamplifier, you can measure signals from devices under test with
low output power, using measurement devices which feature a low sensitivity and do
not have a built-in RF preamplifier.
When you connect the external preamplifier, the R&S FSW reads out the touchdown
(.S2P) file from the EEPROM of the preamplifier. This file contains the s-parameters of
the preamplifier. As soon as you connect the preamplifier to the R&S FSW, the preamplifier is permanently on and ready to use. However, you must enable data correction
based on the stored data explicitly on the R&S FSW using this setting.
Deactivates the preamplifier.
The RF input signal is amplified by about 15 dB.
The RF input signal is amplified by about 30 dB.
When enabled, the R&S FSW automatically compensates the magnitude and phase
characteristics of the external preamplifier in the measurement results. Any internal
preamplifier, if available, is disabled.
For R&S FSW85 models with two RF inputs, you can enable correction from the external preamplifier for each input individually, but not for both at the same time.
When disabled, no compensation is performed even if an external preamplifier remains
connected.
Remote command:
INPut<ip>:EGAin[:STATe] on page 152
5.7 Using the uncertainty calculator
Access: [MEAS CONFIG] > "Uncertainty Calculation"
"Noise figure" measurements are subject to uncertainty. The "noise figure" measurement is meaningless if the measurement uncertainty is too large. Knowing the uncertainty of the "noise figure" measurement adds value especially when comparing measurement results.
Note that the "noise figure" uncertainty is not calculated for frequencies above 67 GHz
because input VSWR values are not specified.
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Configuration
Using the uncertainty calculator
Uncertainty values and systematic error recognition
Note that the uncertainty calculation only takes systematic measurement inaccuracies
into account.
The most significant inaccuracies are:
●
Uncertainties of the noise source and the analyzer
●
Input and output matching
●
"Noise figure" and "gain" of the DUT
●
"Noise figure" of the analyzer
The accuracy of the measurement can also be affected by insufficient repeatability during calibration or measurement.
The repeatability is mainly affected by:
●
Signal-to-noise ratio during calibration and measurement
●
Measurement time (if it is too short)
●
Environmental conditions (e.g. a change in the temperature between measurements)
●
Mechanical stability of the test setup
For more background information on "noise figure" measurement uncertainty, refer to
the application note "The "Y-Factor" Technique for "Noise Figure" Measurement" available for download on the Rohde & Schwarz homepage (http://www.rohde-
schwarz.com/en/applications/the-y-factor-technique-for-noise-figure-measurementsapplication-note_56280-15484.html).
In addition to the parameters described here, the application also considers several
parameters from the general measurement configuration when calculating the uncertainty.
●
Measurement mode
●
2nd Stage Correction
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5.7.1 Configuring noise source characteristics
Configuration
Using the uncertainty calculator
If 2nd stage correction is on, but no calibration data is available, uncertainty is calculated without the 2nd stage correction data.
●
Internal preamplification
●
RF Attenuation
●
Temperature
●
ENR values
Access: [MEAS CONFIG] > "Uncertainty Calculation"
The Uncertainty Calculator supports individual characteristics for a noise source used
during calibration and the measurement.
If you are using a Common ENR, the application assumes that the Output Match and
ENR Uncert(ainty) are the same during calibration and measurement. Only the "Mea-
surement Noise Source" parameters are displayed.
If you are using a different noise source during calibration and measurement, the
Uncertainty Calculator adds an Output Match and ENR Uncert(ainty) required for
uncertainty calculation during calibration.
Note that you have to turn off the Common Noise Source if you have to define the values of the noise source used during calibration.
Common Source for Meas and Cal...............................................................................69
Use SNS Values............................................................................................................69
Output Match.................................................................................................................70
ENR Uncert(ainty).........................................................................................................70
Temperature Uncert(ainty)............................................................................................ 70
Common Source for Meas and Cal
Controls the way the application calculates the uncertainty for the noise source.
Turn on the switch when you use the same noise source during calibration and mea-
surement. Only one set of fields to define the noise source characteristics is available.
The application calculates the uncertainty according to the values you have entered in
there.
Turn the switch off when you use different noise sources during calibration and measurement. The application shows an additional set of fields to define the noise source
characteristics. The uncertainty calculation also includes these values.
The switch is available if you have turned on Common Noise Source.
Remote command:
CALCulate<n>:UNCertainty:COMMon on page 168
Use SNS Values
If enabled, the values from the uncertainty table provided by the (most recently) connected smart noise source are used.
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Configuration
Using the uncertainty calculator
Output Match
Defines the output match of the noise source you are using.
You can define the output match either as the VSWR or as the return loss (RL).
Refer to the datasheet of the noise source for these values.
If a smart noise source is used, the VSWR / RL values defined in the SNS table are
used.
Remote command:
CALCulate<n>:UNCertainty:MATCh:SOURce:CALibration:RL on page 174
CALCulate<n>:UNCertainty:MATCh:SOURce:RL on page 174
CALCulate<n>:UNCertainty:MATCh:SOURce:CALibration[:VSWR]
on page 174
CALCulate<n>:UNCertainty:MATCh:SOURce:CALibration:RL on page 174
ENR Uncert(ainty)
Defines the uncertainty of the excess noise ratio of the noise source you are using.
Refer to the datasheet of the noise source for this value.
Available for noise sources with diode characteristics.
If a smart noise source is used, the ENR uncertainty values defined in the SNS table
are used.
Remote command:
CALCulate<n>:UNCertainty:ENR:UNCertainty on page 171
CALCulate<n>:UNCertainty:ENR:CALibration:UNCertainty on page 170
Temperature Uncert(ainty)
Defines the uncertainty of the hot and cold temperatures of the noise source you are
using.
Refer to the datasheet of the noise source for these values.
Available for resistor noise sources.
Remote command:
CALCulate<n>:UNCertainty:ENR:UNCertainty:COLD on page 171
CALCulate<n>:UNCertainty:ENR:CALibration:UNCertainty:HOT
on page 170
CALCulate<n>:UNCertainty:ENR:CALibration:UNCertainty:COLD
on page 170
CALCulate<n>:UNCertainty:ENR:CALibration:UNCertainty:HOT
on page 170
5.7.2 Configuring DUT characteristics
Access: [MEAS CONFIG] > "Uncertainty Calculation"
Input / Output Match......................................................................................................71
Use Measurement Values............................................................................................. 71
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Configuration
Using the uncertainty calculator
Input / Output Match
Defines the match at the DUT input and output.
You can define the match either as the VSWR or as the return loss (RL). If you define
the VSWR or the return loss, the application automatically calculates the other.
If these values are not defined in the DUT datasheet, determine these values, for
example, with a network analyzer.
Remote command:
CALCulate<n>:UNCertainty:MATCh:DUT:IN[:VSWR] on page 172
CALCulate<n>:UNCertainty:MATCh:DUT:IN:RL on page 172
CALCulate<n>:UNCertainty:MATCh:DUT:OUT[:VSWR] on page 173
CALCulate<n>:UNCertainty:MATCh:DUT:OUT:RL on page 172
Use Measurement Values
Turns automatic determination of the DUT characteristics used for the uncertainty calculation on and off.
If on, the application calculates the uncertainty with the DUT characteristics ("noise figure", "gain" and frequency) resulting from the "noise figure" measurement. For this
method, the application calculates the uncertainty for each measurement point (or frequency) based on the "noise figure" and "gain" results of the last measurement.
If you have selected automatic determination of the DUT characteristics, the application does not show a result in the "NF Uncertainty +/-" field in the dialog box. Instead,
to view the uncertainty at all measurement points, use the "Result Table".
If off, define the "gain", "noise figure" and frequency of the DUT manually for a single
frequency. With this manual determination of the DUT characteristics, the application
only calculates the uncertainty for that frequency and shows the result in the "NF
Uncertainty +/-" field in the dialog box.
●
"Noise Figure" of the DUT
●
"Gain" of the DUT
●
Frequency of the DUT
Remote command:
Control automatic DUT characteristics determination:
CALCulate<n>:UNCertainty[:RESult]? on page 176
Manual definition of DUT characteristics:
CALCulate<n>:UNCertainty:DATA:NOISe on page 169
CALCulate<n>:UNCertainty:DATA:GAIN on page 168
CALCulate<n>:UNCertainty:DATA:FREQuency on page 168
5.7.3 Configuring analyzer characteristics
Access: [MEAS CONFIG] > "Uncertainty Calculation"
For the analyzer characteristics, the application always uses the data specified in the
datasheet of the R&S FSW model you are using. Thus, it is not possible to change or
adjust the analyzer characteristics in any way. The uncertainty calculation takes several analyzer characteristics into account, of which the following are shown as readonly fields in the user interface.
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Configuration
Using the uncertainty calculator
●
SA Input Match: Input match (VSWR or return loss) of the analyzer
●
SA NF Uncert: "Noise figure" uncertainty of the analyzer
●
SA "Gain" Uncert: "Gain" uncertainty of the analyzer
●
SA NF: "Noise figure" of the analyzer
However, if you are using an external preamplifier in the test setup, you have to specify
its characteristics to get a valid uncertainty result.
Remote commands:
CALCulate<n>:UNCertainty:SANalyzer:GAIN:UNCertainty? on page 176
CALCulate<n>:UNCertainty:SANalyzer:NOISe:UNCertainty? on page 177
External Preamplifier (Ext PA).......................................................................................72
└ Preamplifier noise figure (PA NF)................................................................... 72
└ Preamplifier Gain (PA Gain)............................................................................72
└ Net spectrum analyzer noise figure (Net SA NF)............................................72
External Preamplifier (Ext PA)
If enabled, the application automatically calculates and updates the analyzer characteristics based on the characteristics of the external preamplifier defined here.
Refer to the datasheet of the preamplifier you are using for the values you have to
enter.
Remote command:
CALCulate<n>:UNCertainty:PREamp:STATe on page 176
Preamplifier noise figure (PA NF) ← External Preamplifier (Ext PA)
Defines the "noise figure" of the preamplifier.
Remote command:
CALCulate<n>:UNCertainty:PREamp:NOISe on page 175
Preamplifier Gain (PA Gain) ← External Preamplifier (Ext PA)
Defines the "gain" of the preamplifier.
Remote command:
CALCulate<n>:UNCertainty:PREamp:GAIN on page 175
Net spectrum analyzer noise figure (Net SA NF) ← External Preamplifier (Ext PA)
Shows the "noise figure" of the analyzer.
If you are using an external preamplifier, the application calculates the "noise figure" of
the analyzer including the "noise figure" of the preamplifier and shows the result here.
If you do not use an external preamplifier, this value is the same as the "noise figure" of
the analyzer shown in the "SA NF" field.
5.7.4 Guidelines and results
Access: [MEAS CONFIG] > "Uncertainty Calculation"
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Configuration
Using the uncertainty calculator
The lower part of the dialog box contains measurement guidelines that provide information on the quality of measurement and the actual "noise figure" uncertainty.
Guidelines
The guidelines are an indicator of the quality of the measurement and an indicator the
repeatability of the measurement.
The three guidelines are:
●
Make sure that the "noise figure" of the DUT and the "gain" of the DUT is greater
than the "noise figure" of the analyzer plus 1 dB.
●
Make sure that the ENR of the noise source is greater than the "noise figure" of the
DUT plus 5 dB.
●
Make sure that the ENR of the noise source is greater than the "noise figure" of the
analyzer plus 3 dB.
A short form of these guidelines is indicated in the "Uncertainty Calculation" dialog box.
The dialog box also indicates if the guidelines have been met or not by a colored dot.
●
Green light
●
Yellow light : guideline condition not met, but within 1 dB of being met.
●
Red light : guideline condition not met.
Note that the guidelines have no effect on the actual uncertainty that has been calculated and that they are only considered for measurements with 2nd Stage Correction.
Uncertainty
The "Uncertainty" result is shown only if you define the "noise figure" and "gain" characteristics of the DUT manually on a single frequency. In that case, the uncertainty
shown in the "Uncertainty Calculation" dialog box is valid only for the DUT frequency
you have defined.
The "Measurement Offset" evaluates the internal noise of the R&S FSW that is added
to the "noise figure" results. The measurement offset result is displayed when 2nd
stage correction is turned off. When you turn on 2nd stage correction, the internal
noise is automatically removed from the uncertainty results, so the measurement offset
is not shown.
If you are using the "noise figure" and "gain" that has been determined during a measurement, the uncertainty is displayed only in the result table.
For more information, see "Use Measurement Values" on page 71.
SCPI command:
: guideline condition met.
CALCulate<n>:UNCertainty[:RESult]? on page 176
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5.8 Trigger and gate configuration
Configuration
Trigger and gate configuration
Triggering means to capture the interesting part of the signal. Choosing the right trigger
type and configuring all trigger settings correctly allows you to detect various incidents
in your signals.
Gating allows you to restrict measurement analysis to the important part or parts of the
signal, for example bursts.
Noise source for trigger preview
As long as the trigger and gate preview is displayed, a "Noise Source State" function is
available in the "Trigger" menu. This function turns on the noise source temporarily so
that you can see the effects of the trigger and gate settings with the noise source on.
See "Noise Source State" on page 78.
● Trigger settings....................................................................................................... 74
● Gate settings...........................................................................................................78
● Continuous gate settings.........................................................................................79
5.8.1 Trigger settings
Access: "Overview" > "Trigger/Gate"
External triggers from one of the TRIGGER INPUT / OUTPUT connectors on the
R&S FSW are configured in a separate tab of the dialog box.
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Configuration
Trigger and gate configuration
Preview......................................................................................................................... 75
└ Frequency.......................................................................................................75
└ RBW................................................................................................................76
└ Sweep Time....................................................................................................76
Trigger Source...............................................................................................................76
└ Free Run.........................................................................................................76
└ External Trigger 1/2/3..................................................................................... 76
Trigger Level................................................................................................................. 77
Repetition Interval......................................................................................................... 77
Drop-Out Time...............................................................................................................77
Trigger Offset................................................................................................................ 77
Hysteresis..................................................................................................................... 77
Trigger Holdoff...............................................................................................................78
Slope.............................................................................................................................78
Noise Source State....................................................................................................... 78
Preview
The preview mode allows you to try out trigger and gate settings before actually applying them to the current measurement.
The preview diagram displays a zero span measurement at the center frequency with
the defined RBW and sweep time. This is useful to analyze bursts, for example, to
determine the required gate settings.
The trigger and gate settings are applied to the measurement when the dialog box is
closed.
Note: The zero span settings refer only to the preview diagram. The main diagram
remains unchanged.
If preview mode is switched off, any changes to the settings in this dialog box are
applied to the measurement diagram directly. In this case, the zero span settings for
the preview diagram are not displayed.
Frequency ← Preview
Defines the center frequency.
Remote command:
[SENSe:]FREQuency:CENTer on page 127
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Trigger and gate configuration
RBW ← Preview
Defines the bandwidth value. The available resolution bandwidths are specified in the
data sheet. Numeric input is always rounded to the nearest possible bandwidth.
Remote command:
[SENSe:]BANDwidth[:RESolution] on page 147
Sweep Time ← Preview
Defines the sweep time. Allowed values depend on the ratio of span to RBW and RBW
to VBW. For details refer to the data sheet. Numeric input is always rounded to the
nearest possible sweep time.
Remote command:
[SENSe:]SWEep:TIME on page 150
Trigger Source
Selects the trigger source. If a trigger source other than "Free Run" is set, "TRG" is displayed in the channel bar and the trigger source is indicated.
Remote command:
TRIGger[:SEQuence]:SOURce on page 158
Free Run ← Trigger Source
No trigger source is considered. Data acquisition is started manually or automatically
and continues until stopped explicitly.
Remote command:
TRIG:SOUR IMM, see TRIGger[:SEQuence]:SOURce on page 158
External Trigger 1/2/3 ← Trigger Source
Data acquisition starts when the TTL signal fed into the specified input connector
meets or exceeds the specified trigger level.
(See "Trigger Level" on page 77).
Note: The "External Trigger 1" softkey automatically selects the trigger signal from the
"TRIGGER 1 INPUT" connector on the front panel.
For details, see the "Instrument Tour" chapter in the R&S FSW Getting Started manual.
"External Trigger 1"
Trigger signal from the "TRIGGER 1 INPUT" connector.
"External Trigger 2"
Trigger signal from the "TRIGGER 2 INPUT / OUTPUT" connector.
Note: Connector must be configured for "Input" in the "Output" configuration
For R&S FSW85 models, "Trigger 2" is not available due to the second RF input connector on the front panel.
(See the R&S FSW user manual).
"External Trigger 3"
Trigger signal from the "TRIGGER 3 INPUT / OUTPUT" connector on
the rear panel.
Note: Connector must be configured for "Input" in the "Output" configuration.
(See R&S FSW user manual).
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Configuration
Trigger and gate configuration
Remote command:
TRIG:SOUR EXT, TRIG:SOUR EXT2
TRIG:SOUR EXT3
See TRIGger[:SEQuence]:SOURce on page 158
Trigger Level
Defines the trigger level for the specified trigger source.
For details on supported trigger levels, see the instrument data sheet.
Remote command:
TRIGger[:SEQuence]:LEVel[:EXTernal<port>] on page 156
Repetition Interval
Defines the repetition interval for a time trigger.
The shortest interval is 2 ms.
Set the repetition interval to the exact pulse period, burst length, frame length or other
repetitive signal characteristic. If the required interval cannot be set with the available
granularity, configure a multiple of the interval that can be set. Thus, the trigger
remains synchronized to the signal.
Remote command:
TRIGger[:SEQuence]:TIME:RINTerval on page 158
Drop-Out Time
Defines the time that the input signal must stay below the trigger level before triggering
again.
Remote command:
TRIGger[:SEQuence]:DTIMe on page 155
Trigger Offset
Defines the time offset between the trigger event and the start of the sweep.
Offset > 0: Start of the sweep is delayed
Offset < 0: Sweep starts earlier (pretrigger)
Remote command:
TRIGger[:SEQuence]:HOLDoff[:TIME] on page 155
Hysteresis
Defines the distance in dB to the trigger level that the trigger source must exceed
before a trigger event occurs. Setting a hysteresis avoids unwanted trigger events
caused by noise oscillation around the trigger level.
This setting is only available for "IF Power" trigger sources. The range of the value is
between 3 dB and 50 dB with a step width of 1 dB.
Remote command:
TRIGger[:SEQuence]:IFPower:HYSTeresis on page 156
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Configuration
Trigger and gate configuration
Trigger Holdoff
Defines the minimum time (in seconds) that must pass between two trigger events.
Trigger events that occur during the holdoff time are ignored.
Remote command:
TRIGger[:SEQuence]:IFPower:HOLDoff on page 155
Slope
For all trigger sources except time, you can define whether triggering occurs when the
signal rises to the trigger level or falls down to it.
Remote command:
TRIGger[:SEQuence]:SLOPe on page 157
Noise Source State
Access: [TRIG]
Temporarily turns on the noise source so that you can see the effects of the trigger and
gate settings with the noise source on.
This function is only available as long as the trigger and gate preview is displayed.
5.8.2 Gate settings
Access: "Overview" > "Trigger" > "Trigger / Gate Config." > "Gate Settings"
Gate settings define one or more extracts of the signal to be measured.
Gating is not available for measurements on I/Q-based data.
Gated Trigger................................................................................................................79
Gate Mode.................................................................................................................... 79
Gate Delay.................................................................................................................... 79
Gate Length.................................................................................................................. 79
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Configuration
Trigger and gate configuration
Gated Trigger
Switches gated triggering on or off.
If the gate is switched on, a gate signal applied to one of the TRIGGER INPUT connec-
tors or the internal IF power detector controls the sweep.
Remote command:
[SENSe:]SWEep:EGATe on page 159
Gate Mode
Sets the gate mode.
"Edge"
"Level"
Remote command:
[SENSe:]SWEep:EGATe:TYPE on page 164
The trigger event for the gate to open is the detection of the signal
edge.
After the gate signal has been detected, the gate remains open until
the gate length is over.
The trigger event for the gate to open is a particular power level.
After the gate signal has been detected, the gate remains open until
the signal disappears.
This mode is not supported when using R&S Power Sensors as
power triggers ("Trg/Gate Source" = Power Sensor or External).
Gate Delay
Defines the delay time between the gate signal and the continuation of the measurement.
The delay position on the time axis in relation to the sweep is indicated by a line
labeled "GD".
Remote command:
[SENSe:]SWEep:EGATe:HOLDoff on page 161
Gate Length
Defines how long the gate is open when it is triggered.
The gate length can only be set in the edge-triggered gate mode. In the level-triggered
mode the gate length depends on the level of the gate signal.
The gate length in relation to the sweep is indicated by a line labeled "GL".
Remote command:
[SENSe:]SWEep:EGATe:LENGth on page 161
5.8.3 Continuous gate settings
Access: "Overview" > "Trigger" > "Trigger / Gate Config." > "Cont. Gate" tab
Continuous gating allows you to perform a continuous gated sweep after a single
external trigger is received.
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Configuration
Performing measurements
Continuous Gate........................................................................................................... 80
Gate Period Length.......................................................................................................80
Gate Period Count........................................................................................................ 80
Continuous Gate
Activates or deactivates continuous gating.
This setting is only available if Gated Trigger is "On".
If no external trigger is active yet when continuous gating is activated, external trigger 1
is automatically activated as the trigger source.
Remote command:
[SENSe:]SWEep:EGATe:CONTinuous[:STATe] on page 161
Gate Period Length
Defines the length in seconds of a single gate period in continuous gating. The length
is determined from the beginning of one gate measurement to the beginning of the
next one.
Remote command:
[SENSe:]SWEep:EGATe:CONTinuous:PLENgth on page 160
Gate Period Count
Defines the number of gate periods to be measured after a single trigger event in continuous gating.
Remote command:
[SENSe:]SWEep:EGATe:CONTinuous:PCOunt on page 160
5.9 Performing measurements
Access: [SWEEP]
Access (calibration): "Overview" > "Calibrate"
This chapter contains all functionality necessary to control and perform "noise figure"
measurements.
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Configuration
Performing measurements
Continuous Sweep / Run Cont......................................................................................81
Single Sweep / Run Single............................................................................................81
Calibrate........................................................................................................................82
Sweep Time.................................................................................................................. 82
Meas Mode (Auto Manual)............................................................................................82
Continuous Sweep / Run Cont
After triggering, starts the measurement and repeats it continuously until stopped. This
is the default setting.
Initiates a measurement and repeats it continuously until stopped. If necessary, the
application automatically determines the reference level before starting the actual measurement.
While the measurement is running, the "Continuous Sweep" softkey and the [RUN
CONT] key are highlighted. The running measurement can be aborted by selecting the
highlighted softkey or key again. The results are not deleted until a new measurement
is started.
Note: Sequencer. If the Sequencer is active, the "Continuous Sweep" softkey only controls the sweep mode for the currently selected channel. However, the sweep mode
only takes effect the next time the Sequencer activates that channel, and only for a
channel-defined sequence. In this case, a channel in continuous sweep mode is swept
repeatedly.
Furthermore, the [RUN CONT] key controls the Sequencer, not individual sweeps.
[RUN CONT] starts the Sequencer in continuous mode.
For details on the Sequencer, see the R&S FSW User Manual.
Remote command:
INITiate<n>:CONTinuous on page 178
Single Sweep / Run Single
Initiates a single measurement. The measurement is finished after all frequencies in
the frequency list have been measured. If necessary, the application automatically
determines the reference level before starting the actual measurement.
After triggering, initiates a single measurement. The measurement is finished after all
frequencies in the frequency list have been measured. If necessary, the application
automatically determines the reference level before starting the actual measurement.
While the measurement is running, the "Single Sweep" softkey and the [RUN SINGLE]
key are highlighted. The running measurement can be aborted by selecting the highlighted softkey or key again.
Note: Sequencer. If the Sequencer is active, the "Single Sweep" softkey only controls
the sweep mode for the currently selected channel. However, the sweep mode only
takes effect the next time the Sequencer activates that channel, and only for a channel-defined sequence. In this case, the Sequencer sweeps a channel in single sweep
mode only once.
Furthermore, the [RUN SINGLE] key controls the Sequencer, not individual sweeps.
[RUN SINGLE] starts the Sequencer in single mode.
If the Sequencer is off, only the evaluation for the currently displayed channel is updated.
For details on the Sequencer, see the R&S FSW User Manual.
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Configuration
Configuring inputs and outputs of the R&S
Remote command:
INITiate<n>[:IMMediate] on page 179
Calibrate
Initiates a calibration measurement.
For interpolation purposes, R&S FSW-K30 will internally add addiitonal measurement
points at the band switching frequencies. This may increase the time needed to complete the calibration.
For more information see Chapter 4.6, "Calibration (2nd stage correction)",
on page 32.
Remote command:
INITiate<n>[:IMMediate] on page 179
when [SENSe:]CONFigure:CORRection is on.
Sweep Time
Defines the sweep time.
For more information see "Sweep Time" on page 64.
Meas Mode (Auto Manual)
Selects the measurement mode for the hot and cold power measurements.
For more information about the measurement modes see Chapter 4.2, "Measurement
modes", on page 24.
In manual measurement mode, the application opens a dialog box when you start a
measurement. For more information about its contents see "Performing a manual mea-
surement" on page 24.
Remote command:
[SENSe:]CONFigure:CONTrol on page 180
[SENSe:]CONFigure:MEASurement on page 181
FSW
5.10 Configuring inputs and outputs of the R&S FSW
Further input sources
The R&S FSW Noise measurements application application can also process input
from the following optional sources:
●
External mixer
●
External generator
●
Active modular probes
For details, see the R&S FSW I/Q Analyzer and I/Q Input User Manual.
● Radio frequency (RF) input.....................................................................................83
● External generator...................................................................................................85
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Configuration
5.10.1 Radio frequency (RF) input
Access: [INPUT/OUTPUT] > "Input Source Config" > "Input Source" > "Radio Fre-
quency"
The RF input is the default input of the R&S FSW.
Input Coupling...............................................................................................................83
Impedance.................................................................................................................... 83
Direct Path.................................................................................................................... 83
High Pass Filter 1 to 3 GHz...........................................................................................84
YIG-Preselector.............................................................................................................84
Input Connector.............................................................................................................84
Input Coupling
The RF input of the R&S FSW can be coupled by alternating current (AC) or direct current (DC).
For an active external frontend, input coupling is always DC.
AC coupling blocks any DC voltage from the input signal. AC coupling is activated by
default to prevent damage to the instrument. Very low frequencies in the input signal
can be distorted.
However, some specifications require DC coupling. In this case, you must protect the
instrument from damaging DC input voltages manually. For details, refer to the data
sheet.
Remote command:
INPut<ip>:COUPling on page 182
Configuring inputs and outputs of the R&S
FSW
Impedance
For some measurements, the reference impedance for the measured levels of the
R&S FSW can be set to 50 Ω or 75 Ω.
Select 75 Ω if the 50 Ω input impedance is transformed to a higher impedance using a
75 Ω adapter of the RAZ type. (That corresponds to 25Ω in series to the input impedance of the instrument.) The correction value in this case is 1.76 dB = 10 log (75Ω/
50Ω).
Remote command:
INPut<ip>:IMPedance on page 183
Direct Path
Enables or disables the use of the direct path for small frequencies.
In spectrum analyzers, passive analog mixers are used for the first conversion of the
input signal. In such mixers, the LO signal is coupled into the IF path due to its limited
isolation. The coupled LO signal becomes visible at the RF frequency 0 Hz. This effect
is referred to as LO feedthrough.
To avoid the LO feedthrough the spectrum analyzer provides an alternative signal path
to the A/D converter, referred to as the direct path. By default, the direct path is
selected automatically for RF frequencies close to zero. However, this behavior can be
disabled. If "Direct Path" is set to "Off", the spectrum analyzer always uses the analog
mixer path.
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Configuration
Configuring inputs and outputs of the R&S
For an active external frontend, the direct path is always used automatically for frequencies close to zero.
"Auto"
"Off"
Remote command:
INPut<ip>:DPATh on page 184
High Pass Filter 1 to 3 GHz
Activates an additional internal highpass filter for RF input signals from 1 GHz to
3 GHz. This filter is used to remove the harmonics of the analyzer to measure the harmonics for a DUT, for example.
This function requires an additional hardware option.
Note: For RF input signals outside the specified range, the high-pass filter has no
effect. For signals with a frequency of approximately 4 GHz upwards, the harmonics
are suppressed sufficiently by the YIG-preselector, if available.)
Remote command:
INPut<ip>:FILTer:HPASs[:STATe] on page 183
(Default) The direct path is used automatically for frequencies close
to zero.
The analog mixer path is always used.
FSW
YIG-Preselector
Enables or disables the YIG-preselector, if available on the R&S FSW.
An internal YIG-preselector at the input of the R&S FSW ensures that image frequen-
cies are rejected. However, image rejection is only possible for a restricted bandwidth.
To use the maximum bandwidth for signal analysis you can disable the YIG-preselector
at the input of the R&S FSW, which can lead to image-frequency display.
Note: Note that the YIG-preselector is active only on frequencies greater than 8 GHz.
Therefore, switching the YIG-preselector on or off has no effect if the frequency is
below that value.
To use the optional 90 GHz frequency extension (R&S FSW-B90G), the YIG-preselector must be disabled.
Remote command:
INPut<ip>:FILTer:YIG[:STATe] on page 183
Input Connector
Selects the input source.
The Noise application supports the following input sources:
●
RF Input
●
Analog Baseband Input
The "Baseband Input I" requires option R&S FSW-B71.
Remote command:
INPut<ip>:CONNector on page 184
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Configuration
5.10.2 External generator
Access: [INPUT/OUTPUT] > "Input Source Config" > "External Generator"
● Interface configuration settings............................................................................... 85
● Measurement configuration.....................................................................................86
5.10.2.1 Interface configuration settings
Access: "Overview" > "Local Oscillator" > "External Generator" > "Measurement Con-
figuration"
Configuring inputs and outputs of the R&S
FSW
Generator Type.............................................................................................................85
Interface........................................................................................................................ 85
TTL Handshake.............................................................................................................86
GPIB Address/TCPIP Address / Computer Name........................................................ 86
Reference......................................................................................................................86
Edit Generator Setup File..............................................................................................86
Frequency Min/ Frequency Max....................................................................................86
Level Min/ Level Max.................................................................................................... 86
Generator Type
Selects the generator type and thus defines the generator setup file to use.
Remote command:
SYSTem:COMMunicate:RDEVice:GENerator<gen>:TYPE on page 198
Interface
Type of interface connection used.
For details on which signal generators support which interfaces, see the documenta-
tion of the corresponding signal generator.
●
GPIB
●
TCP/IP
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Configuration
Configuring inputs and outputs of the R&S FSW
Remote command:
SYSTem:COMMunicate:RDEVice:GENerator<gen>:INTerface on page 197
TTL Handshake
Turning the TTL handshake on and off has no effect for "Noise Figure" measurements.
GPIB Address/TCPIP Address / Computer Name
For LAN connections: TCP/IP address of the signal generator
For GPIB connections: GPIB address of the signal generator.
Remote command:
SYSTem:COMMunicate:GPIB:RDEVice:GENerator<gen>:ADDRess on page 198
SYSTem:COMMunicate:TCPip:RDEVice:GENerator<gen>:ADDRess
on page 198
Reference
Selects the internal R&S FSW or an external frequency reference to synchronize the
R&S FSW with the generator (default: internal).
Remote command:
SOURce<si>:EXTernal<gen>:ROSCillator[:SOURce] on page 197
Edit Generator Setup File
Displays the setup file for the currently selected Generator Type in read-only mode in
an editor.
Although the existing setup files are displayed in read-only mode in the editor, they can
be saved under a different name (using "File > SaveAs").
For more information, see Chapter 4.4, "External generator control", on page 27.
Frequency Min/ Frequency Max
For reference only: Lower and upper frequency limit for the generator.
Level Min/ Level Max
For reference only: Lower and upper power limit for the generator.
5.10.2.2 Measurement configuration
Access: "Overview" > "Local Oscillator" > "External Generator" > "Measurement Con-
figuration"
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Configuration
Configuring inputs and outputs of the R&S
Automatic Control..........................................................................................................87
Init Before Meas............................................................................................................87
Auto Switch Off..............................................................................................................88
Source Power................................................................................................................88
Frequency Coupling......................................................................................................88
Init External Generator..................................................................................................89
FSW
Automatic Control
Turns automatic control of the external generator on and off.
If on, the application controls the configuration of the external generator during mea-
surements by transmitting the required remote commands. The connection is established automatically before a measurement if Init Before Meas is on. To establish the
connection manually at any time, use the Init External Generator function.
Otherwise, you have to control the generator manually. The application assumes that
the generator is configured correctly for the measurement. The remote connection to
the generator is automatically terminated.
Turn on automatic control to perform Fixed IF measurements with the LO frequency
tuned to the current measurement (RF) frequency. Manual control is recommended
only for measurements whose generator settings remain the same during the measurement.
Remote command:
SYSTem:CONFigure:GENerator:CONTrol:STATe on page 199
Init Before Meas
Turns automatic transmission of the external generator configuration on and off.
If enabled, the application transmits a sequence of remote commands that configures
the generator and turns on its RF output before each measurement. Thus, the generator runs with the required configuration and can still receive remote control commands
during a measurement. Automatic initialization requires a slightly longer measurement
time because of the time required to transmit the commands and configure the generator.
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21 Offset
rDenominato
Numerator
Offsetff
LOGenera tor
Configuration
Configuring inputs and outputs of the R&S
If disabled, you have to initialize the generator manually with Init External Generator.
Note that you have to establish the connection before you can perform a measurement
with the external generator.
Remote command:
SYSTem:CONFigure:GENerator:INITialise:AUTO on page 199
Auto Switch Off
Turns automatic deactivation of the generator's RF output on and off.
If enabled, the application transmits a sequence of remote commands to turn off the
RF output of the generator when a measurement is over. A measurement is over after
a single sweep or if the measurement is aborted. The sequence of commands also
ends the remote control session.
If disabled, you have to turn off the RF output and remote control session manually.
Note that when you close the R&S FSW Noise measurements application, the genera-
tor's RF output is turned off and the remote session is terminated.
Remote command:
SYSTem:CONFigure:GENerator:SWITch:AUTO on page 199
FSW
Source Power
Defines the output power of the external generator.
The range depends on the generator you are using and is defined in its data sheet.
Remote command:
SOURce<si>:EXTernal<gen>:POWer[:LEVel] on page 197
Frequency Coupling
Defines frequency correction characteristics.
The generator frequency is calculated as follows.
With:
●
f
Generator
●
fLO= frequency of the analyzer's LO
●
f
offset<1>
●
f
offset<2>
Use the factors and offsets to compensate one or more components in the test setup
which change the frequency between the generator and the DUT. Make sure, however,
that the result does not exceed the frequency range of the generator.
The application calculates the resulting start and stop frequency based on the values
you apply and displays them below the equation.
Remote command:
SOURce:EXTernal:FREQuency[:FACTor]:DENominator on page 196
SOURce:EXTernal:FREQuency[:FACTor]:NUMerator on page 196
SOURce:EXTernal:FREQuency:OFFSet<of> on page 196
= generator frequency
= offset frequency of the analyzer
= offset frequency of other components
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Configuration
Configuring inputs and outputs of the R&S FSW
Init External Generator
Establishes a connection to generator and turns on its RF output.
You can establish the connection automatically before a measurement if Init Before
Meas is on.
Note that you have to establish the connection before you can perform a measurement
with the external generator.
Remote command:
SYSTem:CONFigure:GENerator:INITialise[:IMMediate] on page 199
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6 Analysis
6.1 Configuring the display
Analysis
Configuring the display
This chapter contains all settings and parameters that the application provides to analyze and evaluate measurement results.
● Configuring the display............................................................................................90
● Working with traces.................................................................................................93
● Using markers.........................................................................................................96
● Limit line settings and functions............................................................................ 101
Access: [MEAS CONFIG] > "Result Config"
Display configuration settings configure the way the results are displayed in the diagram.
The contents depend on whether you want to configure a graphical result display or a
numerical result display.
Specifics for
The settings you make apply to the results you have selected in the "Specifics for"
dropdown menu. If more than one window is active, "Specifics for" also puts the focus
on the corresponding window.
● Configuring graphical results...................................................................................90
● Configuring numerical results..................................................................................92
6.1.1 Configuring graphical results
Access: [MEAS CONFIG] > "Result Config" > "Graph"
When configuring graphical results, the dialog box contains functionality to scale and
set up the diagram axes.
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Y-Axis............................................................................................................................ 91
Auto Scale / Min / Max.................................................................................................. 91
Symbols........................................................................................................................ 92
Uncertainty....................................................................................................................92
X-Axis............................................................................................................................92
Y-Axis
Selects the result display and thus the scaling of the vertical axis.
For more information, see Chapter 3, "Measurements and result displays", on page 13.
Auto Scale / Min / Max
Turns automatic scaling of the vertical axis on and off.
If on, the application optimizes the scaling of the vertical axis after each measurement
for ideal viewing of the results.
If off, you can define the scaling manually. The "Min" and "Max" input fields become
available. These two input fields define the values at the top and bottom of the vertical
axis.
Remote command:
Automatic scaling:
DISPlay[:WINDow<n>]:TRACe<t>:Y[:SCALe]:AUTO on page 202
Manual minimum value:
DISPlay[:WINDow<n>]:TRACe<t>:Y[:SCALe]:BOTTom on page 202
Manual maximum value
DISPlay[:WINDow<n>]:TRACe<t>:Y[:SCALe]:TOP on page 203
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Symbols
Turns symbols that represent a measurement point on the trace on and off.
Remote command:
DISPlay[:WINDow<n>]:TRACe<t>:SYMBols on page 200
Uncertainty
Displays an additional trace indicating the measured trace values ± the uncertainty values determined by the uncertainty calculator. Thus, you obtain a range of minimum
and maximum result values. This trace is only useful for "noise figure" measurements.
Remote command:
DISPlay[:WINDow<n>]:TRACe<t>:UNCertainty on page 201
X-Axis
Selects the frequency data that is displayed on the x-axis.
For measurements on frequency converting DUTs with a variable intermediate fre-
quency, you can display either the RF frequency or the IF frequency.
Note that a change of the x-axis scale applies to all result displays, and also deter-
mines which value is output for trace export.
The "Frequency Axis" scale is also available via the [FREQ] key.
Remote command:
DISPlay[:WINDow<n>]:TRACe<t>:X[:SCALe] on page 201
6.1.2 Configuring numerical results
When configuring numerical results, the dialog box selects the type of results you want
to display in the result table. The results in the table are based on a particular trace
that you can select in the corresponding input field.
You can add an aspect of the measurement by placing a checkmark in front of the corresponding result on and remove it by removing the checkmark.
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For more information on each result, see Chapter 3, "Measurements and result dis-
plays", on page 13.
Remote command:
DISPlay[:WINDow<n>]:TABLe:ITEM on page 200
6.2 Working with traces
Access (trace configuration): [TRACE] > "Trace Config" > "Traces"
Access (trace export): [TRACE] > "Trace Config" > "Trace / Data Export"
Access (copy trace): [TRACE] > "Trace Config" > "Trace Copy"
A trace is the graphical representation of a set of measurement results in a diagram.
Each measurement window that contains graphical results supports up to four individual traces. Each trace has a different color. Trace settings determine how the measured data is analyzed and displayed on the screen. The trace information, including a
color map and trace mode is summarized in the diagram header.
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Traces........................................................................................................................... 94
Smoothing.....................................................................................................................95
Preset Traces................................................................................................................95
Trace Export..................................................................................................................95
└ Export all Traces and all Table Results...........................................................95
└ Include Instrument & Measurement Settings..................................................95
└ Trace to Export............................................................................................... 95
└ Decimal Separator.......................................................................................... 95
└ Export Trace to ASCII File.............................................................................. 95
Copy Trace....................................................................................................................96
Traces
The "Trace 1 to 4" softkeys open the "Traces" tab of the "Trace Configuration" dialog
box.
The "Traces" tab contains functionality to configure a trace.
"Trace Selec-
tion"
"Trace Mode"
Remote command:
Trace mode:
DISPlay[:WINDow<n>][:SUBWindow<w>]:TRACe<t>:MODE on page 204
The "Trace 1" to "Trace 4" buttons select a trace. If a trace is
selected, it is highlighted orange.
Note that you cannot select a trace if its trace mode is "Blank".
Selects the trace mode for the corresponding trace.
For more information, see Chapter 4, "Measurement basics",
on page 22.
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Smoothing
If enabled, the trace is smoothed by the specified value (between 1 % and 50 %). The
smoothing value is defined as a percentage of the display width. The larger the
smoothing value, the greater the smoothing effect.
Remote command:
DISPlay[:WINDow<n>][:SUBWindow<w>]:TRACe<t>:SMOothing[:STATe]
on page 205
DISPlay[:WINDow<n>][:SUBWindow<w>]:TRACe<t>:SMOothing:APERture
on page 205
Preset Traces
Restores the default configuration for all traces in a window.
Trace Export
The "Trace Export" tab contains functionality to export trace data.
Export all Traces and all Table Results ← Trace Export
Selects all displayed traces and result tables (e.g. "Result Summary", marker table
etc.) in the current application for export to an ASCII file.
Alternatively, you can select one specific trace only for export (see Trace to Export).
The results are output in the same order as they are displayed on the screen: window
by window, trace by trace, and table row by table row.
Remote command:
FORMat:DEXPort:TRACes on page 207
Include Instrument & Measurement Settings ← Trace Export
Includes additional instrument and measurement settings in the header of the export
file for result data.
Remote command:
FORMat:DEXPort:HEADer on page 207
Trace to Export ← Trace Export
Defines an individual trace to be exported to a file.
This setting is not available if Export all Traces and all Table Results is selected.
Decimal Separator ← Trace Export
Defines the decimal separator for floating-point numerals for the data export/import
files. Evaluation programs require different separators in different languages.
Remote command:
FORMat:DEXPort:DSEParator on page 206
Export Trace to ASCII File ← Trace Export
Opens a file selection dialog box and saves the selected trace in ASCII format (.dat)
to the specified file and directory.
The results are output in the same order as they are displayed on the screen: window
by window, trace by trace, and table row by table row.
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The column headers are provided as the first row. Whether the frequency value represents the RF or IF frequency depends on the X-Axis setting.
Note: Secure user mode.
In secure user mode, settings that are stored on the instrument are stored to volatile
memory, which is restricted to 256 MB. Thus, a "memory limit reached" error can occur
although the hard disk indicates that storage space is still available.
To store data permanently, select an external storage location such as a USB memory
device.
For details, see "Protecting Data Using the Secure User Mode" in the "Data Management" section of the R&S FSW base unit user manual.
Remote command:
MMEMory:STORe<n>:TRACe on page 207
Copy Trace
Access: "Overview" > "Analysis" > "Traces" > "Copy Trace"
Or: [TRACE] > "Copy Trace"
Copies trace data to another trace.
The first group of buttons (labeled "Trace 1" to "Trace 4") selects the source trace. The
second group of buttons (labeled "Copy to Trace 1" to "Copy to Trace 4") selects the
destination.
Remote command:
TRACe<n>:COPY on page 208
6.3 Using markers
Markers help you to read out measurement results for particular frequencies or mark a
particular point on a trace. The "noise figure" application features four markers. Markers in the "noise figure" application are linked. If you use more than one measurement
window and activate a marker in one window, it also appears in all other measurement
windows on the same horizontal position.
● Marker configuration............................................................................................... 96
● Marker positioning...................................................................................................99
6.3.1 Marker configuration
Access (marker configuration): [MKR] > "Marker Config" > "Marker"
Access (marker settings): [MKR] > "Marker Config" > "Marker Settings"
The "Marker Configuration" dialog box and the "Marker" menu contain all functionality
necessary to control markers.
The "Marker Configuration" dialog box consists of two tabs.
The "Markers" tab contains functionality to define characteristics for each marker.
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The "Marker Settings" tab contains general marker functionality.
Marker (1...4).................................................................................................................98
Marker Type..................................................................................................................98
Marker to Trace.............................................................................................................98
All Markers Off...............................................................................................................98
Marker Config................................................................................................................98
Marker Table Display.....................................................................................................98
Marker Info....................................................................................................................99
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Marker (1...4)
Selects or turns the corresponding marker on and off.
Turning on a marker also opens an input field to define the horizontal position of the
marker.
By default, the first marker you turn on is a normal marker, all others are delta markers.
Marker Type
Toggles the marker type.
The type for marker 1 is always "Normal", the type for delta marker 1 is always "Delta".
These types cannot be changed.
Note: If normal marker 1 is the active marker, switching the "Mkr Type" activates an
additional delta marker 1. For any other marker, switching the marker type does not
activate an additional marker, it only switches the type of the selected marker.
"Normal"
"Delta"
Remote command:
CALCulate<n>:MARKer<m>[:STATe] on page 218
CALCulate<n>:DELTamarker<m>[:STATe] on page 221
A normal marker indicates the absolute value at the defined position
in the diagram.
A delta marker defines the value of the marker relative to the specified reference marker (marker 1 by default).
Marker to Trace
Opens an input field to assign the marker to a particular trace if you are using more
than one trace.
All Markers Off
Deactivates all markers in one step.
Remote command:
CALCulate<n>:MARKer<m>:AOFF on page 218
Marker Config
Opens the "Marker Configuration" dialog box.
The "Marker Configuration" dialog box contains all marker functions necessary to set
up the four markers supported by the application.
●
Selected
Highlights the currently selected marker.
●
State
Turns a marker on and off.
●
X-value
Defines the marker position on the horizontal axis.
●
Type
Selects the marker type. For more information see "Marker Type" on page 98.
●
Trace
Selects the trace the marker is positioned on.
Marker Table Display
Defines how the marker information is displayed.
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"On"
"Off"
Remote command:
DISPlay[:WINDow<n>]:MTABle on page 224
Marker Info
Turns the marker information displayed in the diagram on and off.
Remote command:
DISPlay[:WINDow<n>]:MINFo[:STATe] on page 223
Displays the marker information in a table in a separate area beneath
the diagram.
No separate marker table is displayed.
If Marker Info is active, the marker information is displayed within the
diagram area.
6.3.2 Marker positioning
If you are using more than one measurement window, the application performs the
peak search in the currently selected measurement window. The currently selected
measurement window has a blue border. Because the markers are linked in the "noise
figure" application, the frequency position of the marker in the other window is updated
accordingly, even if it means that the marker is on a peak in one window only.
Select Marker <x>.........................................................................................................99
Peak Search................................................................................................................100
Search Next Peak....................................................................................................... 100
Search Minimum......................................................................................................... 100
Search Next Minimum.................................................................................................100
Marker to Single Frequency........................................................................................101
Select Marker <x>
Opens a dialog box to select and activate or deactivate one or more markers.
The number in the softkey label (<x>) shows the number of the currently selected
marker.
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Remote command:
Marker selected via suffix <m> in remote commands.
Peak Search
Sets the selected marker/delta marker to the maximum of the trace. If no marker is
active, marker 1 is activated.
Remote command:
CALCulate<n>:MARKer<m>:MAXimum[:PEAK] on page 225
CALCulate<n>:DELTamarker<m>:MAXimum[:PEAK] on page 227
Search Next Peak
Sets the selected marker/delta marker to the next (lower) maximum of the assigned
trace. If no marker is active, marker 1 is activated.
Remote command:
CALCulate<n>:MARKer<m>:MAXimum:NEXT on page 225
CALCulate<n>:MARKer<m>:MAXimum:RIGHt on page 225
CALCulate<n>:MARKer<m>:MAXimum:LEFT on page 224
CALCulate<n>:DELTamarker<m>:MAXimum:NEXT on page 227
CALCulate<n>:DELTamarker<m>:MAXimum:RIGHt on page 227
CALCulate<n>:DELTamarker<m>:MAXimum:LEFT on page 226
Search Minimum
Sets the selected marker/delta marker to the minimum of the trace. If no marker is
active, marker 1 is activated.
Remote command:
CALCulate<n>:MARKer<m>:MINimum[:PEAK] on page 226
CALCulate<n>:DELTamarker<m>:MINimum[:PEAK] on page 228
Search Next Minimum
Sets the selected marker/delta marker to the next (higher) minimum of the selected
trace. If no marker is active, marker 1 is activated.
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