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R&S®ESW Spectrum Analysis
User Manual
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Rohde&Schwarz R&S®ESW Spectrum Analysis User Manual

R&S®ESW Spectrum Application User Manual
1177630002 Version 10
This manual describes the following R&S®ESW models:
●
R&S®ESW8 (1328.4100K08)
●
R&S®ESW8 (1328.4100K09)
●
R&S®ESW26 (1328.4100K26)
●
R&S®ESW26 (1328.4100K27)
●
R&S®ESW44 (1328.4100K44)
●
R&S®ESW44 (1328.4100K45)
The contents of this manual correspond to firmware version 2.20 and higher. The Spectrum application is integral part of the R&S®ESW.
© 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.
1177.6300.02 | Version 10 | R&S®ESW
Throughout this manual, products from Rohde & Schwarz are indicated without the ® symbol , e.g. R&S®ESW is indicated as R&S ESW.
R&S®ESW

Contents

Contents
1 Preface.................................................................................................. 11
1.1 About this manual....................................................................................................... 11
1.2 Documentation overview............................................................................................11
1.2.1 Getting started manual..................................................................................................12
1.2.2 User manuals and help................................................................................................. 12
1.2.3 Service manual............................................................................................................. 12
1.2.4 Instrument security procedures.....................................................................................12
1.2.5 Basic safety instructions................................................................................................13
1.2.6 Data sheets and brochures........................................................................................... 13
1.2.7 Release notes and open source acknowledgment (OSA)............................................ 13
1.2.8 Application notes, application cards, white papers, etc.................................................13
1.3 Conventions used in the documentation..................................................................13
1.3.1 Typographical conventions............................................................................................13
1.3.2 Conventions for procedure descriptions........................................................................14
1.3.3 Notes on screenshots................................................................................................... 14
2 Welcome to the spectrum application............................................... 15
2.1 Starting the application.............................................................................................. 15
2.2 Understanding the display information.................................................................... 16
2.3 R&S multiview............................................................................................................. 17
3 Measurements and results..................................................................19
3.1 Basic measurements.................................................................................................. 20
3.1.1 Basic measurement types.............................................................................................20
3.1.2 How to perform a basic sweep measurement...............................................................21
3.1.3 Measurement examples - measuring a sinusoidal signal............................................. 22
3.1.4 Measurement example – measuring levels at low S/N ratios....................................... 25
3.1.5 Measurement examples - measuring signal spectra with multiple signals....................28
3.1.6 Measurement examples in zero span........................................................................... 34
3.2 Channel power and adjacent-channel power (ACLR) measurement..................... 40
3.2.1 About channel power measurements............................................................................40
3.2.2 Channel power results.................................................................................................. 41
3.2.3 Channel power basics...................................................................................................43
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3.2.10 Reference: predefined ACLR user standard XML files................................................. 89
Contents
3.2.4 Channel power configuration........................................................................................ 56
3.2.5 MSR ACLR configuration.............................................................................................. 64
3.2.6 How to perform channel power measurements............................................................ 79
3.2.7 Measurement examples................................................................................................84
3.2.8 Optimizing and troubleshooting the measurement........................................................87
3.2.9 Reference: predefined CP/ACLR standards................................................................. 88
3.3 Carrier-to-noise measurements.................................................................................90
3.3.1 About the measurement................................................................................................91
3.3.2 Carrier-to-noise results..................................................................................................92
3.3.3 Carrier-to-noise configuration........................................................................................92
3.3.4 How to determine the carrier-to-noise ratio...................................................................94
3.4 Occupied bandwidth measurement (OBW).............................................................. 94
3.4.1 About the measurement................................................................................................95
3.4.2 OBW results.................................................................................................................. 97
3.4.3 OBW configuration........................................................................................................ 97
3.4.4 How to determine the occupied bandwidth................................................................... 99
3.4.5 Measurement example................................................................................................101
3.5 Spectrum emission mask (SEM) measurement..................................................... 101
3.5.1 About the measurement..............................................................................................102
3.5.2 Typical applications.....................................................................................................102
3.5.3 SEM results.................................................................................................................102
3.5.4 SEM basics................................................................................................................. 105
3.5.5 SEM configuration....................................................................................................... 116
3.5.6 How to perform a spectrum emission mask measurement......................................... 133
3.5.7 Measurement example: multi-sem measurement....................................................... 138
3.5.8 Reference: SEM file descriptions................................................................................ 139
3.6 Spurious emissions measurement..........................................................................146
3.6.1 About the measurement..............................................................................................146
3.6.2 Spurious emissions measurement results.................................................................. 147
3.6.3 Spurious emissions basics..........................................................................................148
3.6.4 Spurious emissions measurement configuration........................................................ 150
3.6.5 How to perform a spurious emissions measurement.................................................. 156
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Contents
3.6.6 Reference: ASCII export file format (spurious)........................................................... 158
3.7 Statistical measurements (APD, CCDF)..................................................................159
3.7.1 About the measurements............................................................................................ 159
3.7.2 Typical applications.....................................................................................................160
3.7.3 APD and CCDF results............................................................................................... 160
3.7.4 APD and CCDF basics - gated triggering................................................................... 162
3.7.5 APD and CCDF configuration..................................................................................... 163
3.7.6 How to perform an APD or CCDF measurement........................................................ 169
3.7.7 Examples.................................................................................................................... 170
3.7.8 Optimizing and troubleshooting the measurement......................................................173
3.8 Time domain power measurement.......................................................................... 173
3.8.1 About the measurement..............................................................................................174
3.8.2 Time domain power results......................................................................................... 174
3.8.3 Time domain power basics - range definition using limit lines.................................... 175
3.8.4 Time domain power configuration............................................................................... 175
3.8.5 How to measure powers in the time domain............................................................... 177
3.8.6 Measurement example................................................................................................178
3.9 Harmonic distortion measurement..........................................................................179
3.9.1 About the measurement..............................................................................................179
3.9.2 Harmonic distortion basics.......................................................................................... 180
3.9.3 Harmonic distortion results..........................................................................................182
3.9.4 Harmonic distortion configuration................................................................................183
3.9.5 How to determine the harmonic distortion...................................................................185
3.10 Third order intercept (TOI) measurement............................................................... 185
3.10.1 About the TOI measurement.......................................................................................186
3.10.2 TOI basics................................................................................................................... 186
3.10.3 TOI results...................................................................................................................190
3.10.4 TOI configuration.........................................................................................................191
3.10.5 How to determine the third order intercept..................................................................192
3.10.6 Measurement example – measuring the R&S ESW's intrinsic intermodulation..........193
3.11 AM modulation depth measurement.......................................................................195
3.11.1 About the measurement..............................................................................................195
3.11.2 AM modulation depth results.......................................................................................195
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3.11.3 AM modulation depth configuration.............................................................................196
3.11.4 Optimizing and troubleshooting the measurement......................................................197
3.11.5 How to determine the AM modulation depth............................................................... 198
3.12.1 About the EMI measurement...................................................................................... 199
3.12.2 EMI measurement results........................................................................................... 199
3.12.3 EMI measurement basics............................................................................................200
3.12.4 EMI measurement configuration................................................................................. 209
3.12.5 EMI result analysis...................................................................................................... 218
3.12.6 How to perform EMI measurements........................................................................... 218
3.12.7 Measurement example: measuring radio frequency interference............................... 221
3.12.8 Optimizing and troubleshooting EMI measurements.................................................. 223
Contents
3.12 Electromagnetic interference (EMI) measurement................................................ 198
4 Common measurement settings...................................................... 224
4.1 Measurement basics.................................................................................................224
4.1.1 IF and video signal output........................................................................................... 224
4.2 Configuration overview............................................................................................ 224
4.3 Data input and output............................................................................................... 226
4.3.1 Receiving data input and providing data output.......................................................... 226
4.3.2 Input source settings................................................................................................... 230
4.3.3 Configuring the preselector......................................................................................... 232
4.3.4 Optional external generator control.............................................................................232
4.3.5 Optional external mixers............................................................................................. 260
4.3.6 Output settings............................................................................................................ 283
4.4 Frequency and span configuration......................................................................... 286
4.4.1 Impact of the frequency and span settings................................................................. 287
4.4.2 Frequency and span settings...................................................................................... 288
4.4.3 Keeping the center frequency stable - signal tracking................................................ 292
4.4.4 How to define the frequency range............................................................................. 293
4.4.5 How to move the center frequency through the frequency range............................... 294
4.5 Amplitude and vertical axis configuration..............................................................294
4.5.1 Impact of the vertical axis settings.............................................................................. 295
4.5.2 Amplitude settings.......................................................................................................297
4.5.3 Scaling the Y-Axis....................................................................................................... 300
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Contents
4.5.4 How to optimize the amplitude display........................................................................302
4.6 Bandwidth, filter and sweep configuration.............................................................302
4.6.1 Impact of the bandwidth, filter and sweep settings..................................................... 303
4.6.2 Bandwidth, filter and sweep settings...........................................................................309
4.6.3 Reference: list of available RRC and Channel filters.................................................. 317
4.7 Trigger and gate configuration................................................................................ 319
4.7.1 Triggering.................................................................................................................... 319
4.7.2 Gating..........................................................................................................................329
4.8 Adjusting settings automatically.............................................................................334
5 Common analysis and display functions........................................ 337
5.1 Result display configuration....................................................................................337
5.1.1 Basic evaluation methods........................................................................................... 337
5.1.2 Laying out the result display with the smartgrid.......................................................... 340
5.2 Zoomed displays.......................................................................................................344
5.2.1 Single zoom versus multiple zoom..............................................................................345
5.2.2 Zoom functions............................................................................................................346
5.2.3 How to zoom into a diagram....................................................................................... 348
5.3 Configuring traces.................................................................................................... 351
5.3.1 Basic information about traces....................................................................................351
5.3.2 Trace configuration......................................................................................................367
5.3.3 How to configure traces.............................................................................................. 383
5.3.4 References..................................................................................................................389
5.4 Marker usage............................................................................................................. 392
5.4.1 Basics on markers.......................................................................................................393
5.4.2 Marker settings............................................................................................................396
5.4.3 Marker search settings and positioning functions....................................................... 401
5.4.4 Marker (measurement) functions................................................................................ 407
5.4.5 How to work with markers........................................................................................... 429
5.4.6 Measurement example: measuring harmonics using marker functions...................... 431
5.5 Display and limit lines.............................................................................................. 433
5.5.1 Display lines................................................................................................................ 433
5.5.2 Limit lines.................................................................................................................... 436
6 Remote commands in the spectrum application............................ 453
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Contents
6.1 Introduction............................................................................................................... 453
6.1.1 Conventions used in descriptions............................................................................... 453
6.1.2 Long and short form.................................................................................................... 454
6.1.3 Numeric suffixes..........................................................................................................454
6.1.4 Optional keywords.......................................................................................................455
6.1.5 Alternative keywords................................................................................................... 455
6.1.6 SCPI parameters.........................................................................................................455
6.2 Common suffixes...................................................................................................... 458
6.3 Application selection................................................................................................ 458
6.4 General window commands.....................................................................................461
6.5 Screen layout.............................................................................................................463
6.6 Preset......................................................................................................................... 470
6.7 Measurement configuration..................................................................................... 470
6.7.1 Measurement control.................................................................................................. 470
6.7.2 Power measurements................................................................................................. 473
6.7.3 Channel power and ACLR.......................................................................................... 478
6.7.4 Carrier-to-noise ratio................................................................................................... 519
6.7.5 Occupied bandwidth....................................................................................................520
6.7.6 Spectrum emission mask (SEM).................................................................................522
6.7.7 Spurious emissions..................................................................................................... 558
6.7.8 Statistics......................................................................................................................571
6.7.9 Time domain power.....................................................................................................581
6.7.10 Harmonic distortion..................................................................................................... 591
6.7.11 Third order intercept point (TOI)..................................................................................594
6.7.12 AM modulation depth.................................................................................................. 597
6.7.13 List evaluations........................................................................................................... 600
6.7.14 Measuring the pulse power......................................................................................... 604
6.7.15 EMI measurements..................................................................................................... 608
6.7.16 Programming example: EMI measurement.................................................................616
6.7.17 Programming example: carrier-to-noise ratio..............................................................618
6.7.18 Programming example: performing a basic frequency sweep.................................... 619
6.8 Configuration.............................................................................................................622
6.8.1 Inputs and output configuration...................................................................................622
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Contents
6.8.2 Frequency configuration..............................................................................................655
6.8.3 Amplitude configuration...............................................................................................661
6.8.4 Y-Axis scaling..............................................................................................................665
6.8.5 Bandwidth configuration..............................................................................................668
6.8.6 Sweep configuration....................................................................................................671
6.8.7 Trigger configuration................................................................................................... 677
6.8.8 Automatic configuration...............................................................................................684
6.9 Analysis..................................................................................................................... 687
6.9.1 Zoom........................................................................................................................... 688
6.9.2 Trace configuration......................................................................................................691
6.9.3 Marker configuration................................................................................................... 714
6.9.4 Lines............................................................................................................................771
List of commands.............................................................................. 789
Index....................................................................................................802
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Contents
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1 Preface

1.1 About this manual

This User Manual provides all the information specific to RF measurements in the Spectrum application. All other operating modes and applications are described in
the specific application manuals.
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 R&S ESW
Introduction to and getting familiar with the instrument
●
Measurements
Descriptions of the individual measurements in the Spectrum application, including result types and configuration settings.
●
Common Measurement Settings
Description of the measurement settings common to all measurement types with their corresponding remote control commands
●
Common Measurement Analysis and Display Functions
Description of the settings and functions provided to analyze results independently of the measurement type with their corresponding remote control commands
●
Remote Commands
Remote commands required to configure and perform measurements in a remote environment, sorted by tasks Remote commands required to set up the environment and to perform common tasks on the instrument, sorted by tasks Programming examples demonstrate the use of many commands and can usually be executed directly for test purposes
●
List of Commands
Alphabetical list of all remote commands described in the manual
●
Index
Preface
Documentation overview

1.2 Documentation overview

This section provides an overview of the R&S ESW user documentation. You find it on the product page at:
www.rohde-schwarz.com/manual/esw
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1.2.1 Getting started manual

1.2.2 User manuals and help

Preface
Documentation overview
Introduces the R&S ESW and describes how to set up and start working with the prod­uct. Includes basic operations, typical measurement examples, and general informa­tion, e.g. safety instructions, etc.
A printed version is delivered with the instrument. A PDF version is available for down­load on the Internet.
Separate user manuals are provided for the base unit and the firmware applications:
●
Base unit manual Contains the description of all instrument modes and functions. It also provides an introduction to remote control, a complete description of the remote control com­mands with programming examples, and information on maintenance, instrument interfaces and error messages. Includes the contents of the getting started manual.
●
Manuals for (optional) firmware applications Contains the description of the specific functions of a firmware application, includ­ing remote control commands. Basic information on operating the R&S ESW is not included.
The contents of the user manuals are available as help in the R&S ESW. The help offers quick, context-sensitive access to the complete information for the base unit and the firmware applications.
All user manuals are also available for download or for immediate display on the Inter­net.

1.2.3 Service manual

Describes the performance test for checking the rated specifications, module replace­ment and repair, firmware update, troubleshooting and fault elimination, and contains mechanical drawings and spare part lists.
The service manual is available for download for registered users on the global Rohde & Schwarz information system (GLORIS):
https://gloris.rohde-schwarz.com

1.2.4 Instrument security procedures

Deals with security issues when working with the R&S ESW in secure areas. It is avail­able for download on the Internet.
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1.2.5 Basic safety instructions

1.2.6 Data sheets and brochures

1.2.7 Release notes and open source acknowledgment (OSA)

Preface
Conventions used in the documentation
Contains safety instructions, operating conditions and further important information. The printed document is delivered with the instrument.
The data sheet contains the technical specifications of the R&S ESW. It also lists the options and their order numbers, and optional accessories.
The brochure provides an overview of the instrument and deals with the specific char­acteristics.
See www.rohde-schwarz.com/brochure-datasheet/esw
The release notes list new features, improvements and known issues of the current firmware version, and describe the firmware installation.
The open source acknowledgment document provides verbatim license texts of the used open source software.
See www.rohde-schwarz.com/firmware/esw

1.2.8 Application notes, application cards, white papers, etc.

These documents deal with special applications or background information on particu­lar topics.
See www.rohde-schwarz.com/application/esw

1.3 Conventions used in the documentation

1.3.1 Typographical conventions

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.
All names of graphical user interface elements on the screen, such as dialog boxes, menus, options, buttons, and softkeys are enclosed by quotation marks.
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Preface
Conventions used in the documentation
Convention Description
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-
Filenames, commands, coding samples and screen output are distin­guished by their font.
tion marks.

1.3.2 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.

1.3.3 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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Welcome to the spectrum application
Starting the application

2 Welcome to the spectrum application

The Spectrum application is a firmware application that adds functionality to perform signal and spectrum analysis to the R&S ESW. The application is part of the R&S ESW firmware.
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 Receiver appli­cation and are described in the R&S ESW User Manual. The latest versions of the manuals are available for download at the product homepage.
http://www2.rohde-schwarz.com/product/ESW.html.
Installation
Find detailed installing instructions in the Getting Started or the release notes of the R&S ESW.
● Starting the application............................................................................................15
● Understanding the display information....................................................................16
● R&S multiview.........................................................................................................17

2.1 Starting the application

Access: [MODE] > "Spectrum"
Multiple Measurement Channels and Sequencer Function
When you enter an application, a new measurement channel is created which deter­mines the measurement settings for that application. The same application can be acti­vated with different measurement settings by creating several channels 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, in order to perform the configured measurements consecu­tively, a Sequencer function is provided.
If activated, the measurements configured in the currently active channels are per­formed one after the other in the order of the tabs. The currently active measurement is indicated by a 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. The result displays of the individual channels
For details on the Sequencer function see the R&S ESW User Manual.
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Welcome to the spectrum application
Understanding the display information

2.2 Understanding the display information

The following figure shows the display as it looks for measurements in spectrum mode. All different information areas are labeled. They are explained in more detail in the fol­lowing sections.
1
Figure 2-1: Screen layout of the noise figure measurement application
42 3 5 6
1 = Toolbar 2 = Channel bar 3 = Diagram header 4 = Result display 5 = Status bar 6 = Softkey bar
Channel bar information
The channel bar contains information about the current measurement setup, progress and results.
Figure 2-2: Channel bar of the Spectrum application
Ref Level Reference level of the R&S ESW.
Att Attenuation of the R&S ESW.
Input Input and input coupling
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Welcome to the spectrum application
R&S multiview
SWT Sweep time
PS Preselector state
RBW Resolution bandwidth
VBW Video bandwidth
Mode Currently selected measurement mode, including the sweep count.
Frequency Center frequency
Window title bar information
For each diagram, the header provides the following information:
1 2 3 4
Figure 2-3: Window title bar information for the Noise Figure application
1 = Window number 2 = Window type 3 = Trace color and number 4 = Trace mode and detector
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.

2.3 R&S multiview

Each application is displayed in a separate tab. An additional tab ("MultiView") provides an overview of all currently active channels at a glance. In the "MultiView" tab, each individual window contains its own channel bar with an additional button. Select this button to switch to the corresponding channel display quickly.
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Welcome to the spectrum application
R&S multiview
Remote command:
DISPlay:FORMat on page 462
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Measurements and results

3 Measurements and results

Access: "Overview" > "Select Measurement"
Or: [MEAS]
In the Spectrum application, the R&S ESW provides a variety of different measurement functions.
●
Basic measurements - measure the spectrum of your signal or watch your signal in time domain
●
Power measurements - calculate the powers involved in modulated carrier signals
●
Emission measurements - detect unwanted signal emission
●
Statistic measurements - evaluate the spectral distribution of the signal
●
Special measurements - provide characteristic values of the signal
●
EMI measurements - detect electromagnetic interference in the signal
The individual functions are described in detail in the following chapters.
The measurement function determines which settings, functions and evaluation meth­ods are available in the R&S ESW. The various measurement functions are described in detail here.
When you select a measurement function, the measurement is started with its default settings immediately and the corresponding measurement configuration menu is dis­played. The measurement configuration menu can be displayed at any time by press­ing the [MEAS CONFIG] key.
The easiest way to configure measurements is using the configuration "Overview", see
Chapter 4.2, "Configuration overview", on page 224.
In addition to the measurement-specific parameters, the general parameters can be configured as usual, see Chapter 4, "Common measurement settings", on page 224. Many measurement functions provide special result displays or evaluation methods; however, in most cases the general evaluation methods are also available, see Chap-
ter 5, "Common analysis and display functions", on page 337.
The remote commands required to retrieve measurement results are described in
Chapter 6.9.2.1, "Trace data retrieval", on page 691.
● Basic measurements...............................................................................................20
● Channel power and adjacent-channel power (ACLR) measurement......................40
● Carrier-to-noise measurements.............................................................................. 90
● Occupied bandwidth measurement (OBW).............................................................94
● Spectrum emission mask (SEM) measurement....................................................101
● Spurious emissions measurement........................................................................146
● Statistical measurements (APD, CCDF)............................................................... 159
● Time domain power measurement........................................................................173
● Harmonic distortion measurement........................................................................ 179
● Third order intercept (TOI) measurement............................................................. 185
● AM modulation depth measurement..................................................................... 195
● Electromagnetic interference (EMI) measurement................................................198
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3.1.1 Basic measurement types

Measurements and results
Basic measurements

3.1 Basic measurements

Basic measurements are common sweeps in the time or frequency domain which pro­vide an overview of the basic input signal characteristics.
If no other measurement function is selected, or if all measurement functions are switched off, the R&S ESW performs a basic frequency or time sweep.
Use the general measurement settings to configure the measurement, e.g. via the "Overview" (see Chapter 4, "Common measurement settings", on page 224).
Frequency Sweep......................................................................................................... 20
Zero Span..................................................................................................................... 20
All Functions Off............................................................................................................21
Frequency Sweep
A common frequency sweep of the input signal over a specified span. Can be used for general purposes to obtain basic measurement results such as peak levels and spec­trum traces. The "Frequency" menu is displayed. This is the default measurement if no other function is selected.
Use the general measurement settings to configure the measurement, e.g. via the "Overview" (see Chapter 4, "Common measurement settings", on page 224).
Remote command:
[SENSe:]FREQuency:STARt on page 658, [SENSe:]FREQuency:STOP
on page 658
INITiate<mt>[:IMMediate] on page 471 INITiate<n>:CONTinuous on page 472
Zero Span
A sweep in the time domain at the specified (center) frequency, i.e. the frequency span is set to zero. The display shows the time on the x-axis and the signal level on the y­axis, as on an oscilloscope. On the time axis, the grid lines correspond to 1/10 of the current sweep time.
Use the general measurement settings to configure the measurement, e.g. via the "Overview" (see Chapter 4, "Common measurement settings", on page 224).
Most result evaluations can also be used for zero span measurements, although some functions (e.g. markers) may work slightly differently and some may not be available. If so, this will be indicated in the function descriptions (see Chapter 5, "Common analysis
and display functions", on page 337).
Remote command:
[SENSe:]FREQuency:SPAN on page 658 INITiate<mt>[:IMMediate] on page 471 INITiate<n>:CONTinuous on page 472
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3.1.2 How to perform a basic sweep measurement

Measurements and results
Basic measurements
All Functions Off
Switches off all measurement functions and returns to a basic frequency sweep. Selecting "Frequency Sweep" has the same effect.
The following step-by-step instructions demonstrate how to perform basic sweep mea­surements.
For remote operation, see Chapter 6.7.18, "Programming example: performing a basic
frequency sweep", on page 619.
To perform one or more single sweeps
1. Configure the frequency and span to be measured ("Frequency" dialog box, see
Chapter 4.4, "Frequency and span configuration", on page 286).
2. Configure the number of sweeps to be performed in a single measurement ("Sweep Config" dialog box, see "Sweep/Average Count" on page 313).
3. If necessary, configure how the signal is processed internally ("Bandwidth" dialog box, see "Sweep Type" on page 315).
4. If necessary, configure a trigger for the measurement ("Trigger/ Gate Config" dialog box, see Chapter 4.7, "Trigger and gate configuration", on page 319).
5. Define how the results are evaluated for display ("Trace" dialog box, see Chap-
ter 5.3.2.1, "Trace settings", on page 367).
6. If necessary, configure the vertical axis of the display ("Amplitude" dialog box, see
Chapter 4.5.3, "Scaling the Y-Axis", on page 300).
7. To start the measurement, select one of the following:
● [RUN SINGLE] key
● "Single Sweep" softkey in the "Sweep" menu The defined number of sweeps are performed, then the measurement is stopped.
While the measurement is running, the [RUN SINGLE] key is highlighted. To abort the measurement, press the [RUN SINGLE] key again. The key is no longer high­lighted. The results are not deleted until a new measurement is started.
8. To repeat the same number of sweeps without deleting the last trace, select the "Continue Single Sweep" softkey in the "Sweep" menu.
To start continuous sweeping
1. If you want to average the trace or search for a maximum over more (or less) than 10 sweeps, configure the "Sweep/Average Count" ("Sweep Config" dialog box, see
"Sweep/Average Count" on page 313).
2. To start the measurement, select one of the following:
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3.1.3 Measurement examples - measuring a sinusoidal signal

Measurements and results
Basic measurements
● [RUN CONT] key
● "Continuous Sweep" softkey in the "Sweep" menu After each sweep is completed, a new one is started automatically. While the mea-
surement is running, the [RUN CONT] key is highlighted. To stop the measure­ment, press the [RUN CONT] key again. The key is no longer highlighted. The results are not deleted until a new measurement is started.
One of the most common measurement tasks that can be handled using a signal ana­lyzer is determining the level and frequency of a signal. When measuring an unknown signal, you can usually start with the presettings.
Test setup
1. Configure the signal generator (e.g. R&S SMW):
● Frequency: 128 MHz
● Level: -30 dBm
NOTICE! Signal levels exceeding 30 dBm can damage the RF attenuator or the
2. input mixer. When calculating the expected power level, consider the total power of all occuring signals.
If you measure signals higher than +30 dBm (=1 W), insert a power attenuator before the RF input of the analyzer.
3. Connect the RF output of the signal generator to the RF input of the R&S ESW.
● Measuring the level and frequency using markers..................................................22
● Measuring the signal frequency using the signal counter....................................... 24
3.1.3.1 Measuring the level and frequency using markers
The level and frequency of a sinusoidal signal can be measured easily using the marker function. The R&S ESW always displays its amplitude and frequency at the marker position. The frequency measurement uncertainty is determined by the refer­ence frequency of the R&S ESW, the resolution of the marker frequency display and the number of sweep points.
1. Select [PRESET] to reset the instrument.
2. Enter the Spectrum application via the [MODE] key.
3. Connect the signal to be measured to the "RF INPUT" connector on the R&S ESW.
4. Set the center frequency to 128
5. Reduce the frequency span to 1 MHz.
MHz.
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Measurements and results
Basic measurements
Note: Coupled settings. When the frequency span is defined, the resolution band­width, the video bandwidth and the sweep time are automatically adjusted, because these functions are defined as coupled functions in the presettings.
6. Select [MKR] to activate marker 1 and automatically set it to the maximum of the trace.
The level and frequency values measured by the marker are displayed in the marker information at the top of the display.
Note: Performing a peak search. When a marker is initially activated, it automati­cally performs the peak search function (as shown in the example). If a marker was already active, select the [Peak Search] key or the "Peak" softkey in the [MKR >] menu in order to set the currently active marker to the maximum of the displayed signal.
Increasing the frequency resolution
The frequency resolution of the marker is determined by the resolution of the trace. A trace consists of 1001 trace points, i.e. if the frequency span is 1 MHz, each trace point represents a span of approximately 1 kHz. This corresponds to a maximum uncertainty of +/- 0.5 kHz.
You can increase the resolution of the trace by reducing the frequency span.
Reducing the frequency span to 10 kHz
► Reduce the frequency span to 10 kHz.
The resolution of the trace is now approximately 10 Hz (10 kHz span / 1001 trace points), thus, the precision of the marker frequency display increases to approxi­mately ±5 Hz.
Setting the reference level
The reference level is the level at the upper limit of the diagram. To achieve the widest dynamic range possible for a spectrum measurement, use the entire level span of the R&S ESW. In other words, the highest level that occurs in the signal should be located at the top edge of the diagram ( = reference level) or immediately below it.
Low Reference Levels
If the selected reference level is lower than the highest signal that occurs in the spec­trum, the signal path in the R&S ESW is overloaded.
In this case, the message "IFOVL" is displayed in the error message field.
In the presettings, the value of the reference level is 0 dBm. If the input signal is
-30 dBm, the reference level can be reduced by 30 dB without causing the signal path
to be overloaded.
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3.1.3.2 Measuring the signal frequency using the signal counter
Measurements and results
Basic measurements
Reducing the reference level by 30 dB
► Set the reference level to -30 dBm.
The maximum of the trace is near the maximum of the measurement diagram. The increase in the displayed noise is not substantial. Thus, the distance between the signal maximum and the noise display (=dynamic range) has increased.
Setting the reference level with the help of a marker
You can also use a marker to shift the maximum value of the trace directly to the top edge of the diagram. If the marker is located at the maximum level of the trace (as in this example), the reference level can be moved to the marker level as follows:
1. Press the [MKR ->] key.
2. Select "Ref Lvl = Mkr Lvl".
The reference level is set to the current marker level.
The built-in signal counter allows you to measure the frequency more accurately than measuring it with the marker. The frequency sweep is stopped at the marker, and the R&S ESW measures the frequency of the signal at the marker position (see also Chap-
ter 5.4.4.1, "Precise frequency (signal count) marker", on page 408).
In the following example, the frequency of the generator at 128 MHz is shown using the marker.
Prerequisite
Precise frequency measurements require a precise reference frequency. Therefore, an external reference frequency from the signal generator is used. Connect the signal generator's "Ref OUT" connector to the analyzer's "Ref IN" connector.
1. Select [PRESET] to reset the instrument.
2. Enter the Spectrum application via the [MODE] key.
3. Set the center frequency to 128 MHz.
4. Set the frequency span to 1 MHz.
5. Select "Setup" > "Reference" > "External Reference 10 MHz" to activate the exter­nal reference frequency.
6. Select [MKR] to activate marker 1 and automatically set it to the maximum of the trace.
The level and the frequency of the marker are displayed in the marker results in the diagram or the marker table.
7. Select [MKR FUNC] > "Signal Count" to activate the signal counter. The result of the signal counter is displayed in the marker results.
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3.1.4 Measurement example – measuring levels at low S/N ratios

Measurements and results
Basic measurements
8. If necessary, increase the resolution of the signal counter by selecting "Signal Count Resolution" (in the "Signal Count" menu).
Prerequisites for using the internal signal counter
In order to obtain a correct result when measuring the frequency with the internal sig­nal counter, an RF sinusoidal signal or a spectral line must be available. The marker must be located more than 25 dB above the noise level to ensure that the specified measurement accuracy is adhered to.
The minimum signal level a signal analyzer can measure is limited by its intrinsic noise. Small signals can be swamped by noise and therefore cannot be measured. For sig­nals that are just above the intrinsic noise, the accuracy of the level measurement is influenced by the intrinsic noise of the R&S ESW.
The displayed noise level of a signal analyzer depends on its noise figure, the selected RF attenuation, the selected reference level, the selected resolution and video band­width and the detector.
For details see:
●
"Attenuation" on page 299
●
Chapter 4.5.1.1, "Reference level", on page 295
●
Chapter 4.6.1.1, "Separating signals by selecting an appropriate resolution band­width", on page 303
●
Chapter 4.6.1.2, "Smoothing the trace using the video bandwidth", on page 304
●
Chapter 5.3.1.1, "Mapping samples to sweep points with the trace detector",
on page 351
This measurement example shows the different factors influencing the S/N ratio.
Table 3-1: Signal generator settings (e.g. R&S SMW)
Frequency 128 MHz
Level -95 dBm
1. Preset the R&S ESW.
2. Enter the Spectrum application via the [MODE] key.
3. Set the center frequency to 128 MHz.
4. Set the span to 100 MHz.
5. Set the reference level to -30
dBm.
The signal is measured with the auto peak detector and is completely hidden in the intrinsic noise of the R&S ESW.
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Measurements and results
Basic measurements
Figure 3-1: Sine wave signal with low S/N ratio
6. To suppress noise spikes, average the trace. In the "Traces" configuration dialog, set the "Trace Mode" to "Average" (see "Trace Mode" on page 368).
The traces of consecutive sweeps are averaged. To perform averaging, the R&S ESW automatically switches on the sample detector. The RF signal, therefore, can be more clearly distinguished from noise.
Figure 3-2: RF sine wave signal with low S/N ratio with an averaged trace
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Measurements and results
Basic measurements
7. Instead of trace averaging, you can select a video filter that is narrower than the resolution bandwidth. Set the trace mode back to "Clear/ Write", then set the VBW to 10 kHz manually in the "Bandwidth" configuration dialog.
The RF signal can be distinguished from noise more clearly.
Figure 3-3: RF sine wave signal with low S/N ratio with a smaller video bandwidth
8. By reducing the resolution bandwidth by a factor of 10, the noise is reduced by 10 dB. Set the RBW to 100 kHz.
The displayed noise is reduced by approximately 10 dB. The signal, therefore, emerges from noise by about 10 dB. Compared to the previous setting, the video bandwidth has remained the same, i.e. it has increased relative to the smaller reso­lution bandwidth. The averaging effect of the video bandwidth is therefore reduced. The trace will be noisier.
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Measurements and results
Basic measurements
Figure 3-4: Reference signal at a smaller resolution bandwidth

3.1.5 Measurement examples - measuring signal spectra with multiple signals

● Separating signals by selecting the resolution bandwidth...................................... 28
● Measuring the modulation depth of an AM-modulated carrier in the frequency
domain.................................................................................................................... 31
● Measuring AM-modulated signals...........................................................................32
3.1.5.1 Separating signals by selecting the resolution bandwidth
A basic feature of a Signal and Spectrum Analyzer is the ability to separate the spec­tral components of a mixture of signals. The resolution at which the individual compo­nents can be separated is determined by the resolution bandwidth. Selecting a resolu­tion bandwidth that is too large may make it impossible to distinguish between spectral components, i.e. they are displayed as a single component (see also Chapter 4.6.1.1,
"Separating signals by selecting an appropriate resolution bandwidth", on page 303).
Two signals with the same amplitude can be resolved if the resolution bandwidth is smaller than or equal to the frequency spacing of the signal. If the resolution bandwidth is equal to the frequency spacing, the spectrum display shows a level drop of 3 dB pre­cisely in the center of the two signals. Decreasing the resolution bandwidth makes the level drop larger, which thus makes the individual signals clearer.
In this measurement example we will analyze two signals with a level of -30 dBm each and a frequency spacing of 30 kHz.
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Signal
Generator 1
Coupler
[-6 dB]
R&S ESW
Signal
Generator 2
Figure 3-5: Test setup
Table 3-2: Signal generator settings (e.g. R&S SMW)
Measurements and results
Basic measurements
Signal generator 1 -30 dBm 128,00 MHz
Signal generator 2 -30 dBm 128,03 MHz
Level Frequency
1. Select [PRESET] to reset the instrument.
2. Enter the Spectrum application via the [MODE] key.
3. Set the center frequency to 128.015
MHz.
4. Set the frequency span to 300 kHz.
5. Set the resolution bandwidth to 30 kHz and the video bandwidth to 1 kHz.
Note: Larger video bandwidths. The video bandwidth is set to 1 kHz in order to make the level drop in the center of the two signals clearly visible. At larger video bandwidths, the video voltage that results from envelope detection is not suffi­ciently suppressed. This produces additional voltages, which are visible in the trace, in the transition area between the two signals.
Figure 3-6: Measurement of two equally-leveled RF sinusoidal signals with the resolution band-
width which corresponds to the frequency spacing of the signals
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Measurements and results
Basic measurements
Matching generator and R&S ESW frequencies
The level drop is located exactly in the center of the display only if the generator frequencies match the frequency display of the R&S ESW exactly. To achieve exact matching, the frequencies of the generators and the R&S ESW must be synchronized.
6. Set the resolution bandwidth to 100 kHz.
It is no longer possible to clearly distinguish the two generator signals.
Figure 3-7: Measurement of two equally-leveled RF sinusoidal signals with a resolution band-
width which is larger than their frequency spacing
7. Set the resolution bandwidth to 1 kHz.
The two generator signals are shown with high resolution. However, the sweep time becomes longer. At smaller bandwidths, the noise display decreases simulta­neously (10 dB decrease in noise floor for a decrease in bandwidth by a factor of
10).
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