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R&S®FSW-K15
Avionics (VOR/ILS) Measurements
User Manual
(;ÛËÙ2)
1177617502
Version 12
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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)
The following firmware options are described:
●
R&S FSW-K15 (1331.4388.02)
© 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.
1177.6175.02 | Version 12 | R&S®FSW-K15
The following abbreviations are used throughout this manual: R&S®FSW is abbreviated as R&S FSW.
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R&S®FSW-K15
1 Documentation overview.......................................................................7
1.1 Getting started manual................................................................................................. 7
1.2 User manuals and help.................................................................................................7
1.3 Service manual..............................................................................................................7
1.4 Instrument security procedures.................................................................................. 8
1.5 Printed safety instructions...........................................................................................8
1.6 Data sheets and brochures.......................................................................................... 8
1.7 Release notes and open-source acknowledgment (OSA).........................................8
1.8 Application notes, application cards, white papers, etc........................................... 8
2 Welcome to the R&S FSW Avionics (VOR/ILS) measurements appli-
Contents
Contents
cation.......................................................................................................9
2.1 Starting the R&S FSW Avionics (VOR/ILS) measurements application...................9
2.2 Understanding the display information.................................................................... 10
3 Measurement basics............................................................................13
3.1 General information on ILS and VOR/DVOR............................................................ 13
3.1.1 The instrument landing system (ILS)............................................................................ 13
3.1.2 VHF omnidirectional radio range (VOR)....................................................................... 16
3.1.3 DVOR (doppler VHF omni-directional range)................................................................18
3.2 Description of the VOR/ILS measurement demodulator......................................... 19
3.2.1 Circuit description - block diagrams.............................................................................. 19
3.2.2 ILS demodulator............................................................................................................20
3.2.3 VOR demodulator......................................................................................................... 23
3.3 Impact of specific parameters................................................................................... 25
3.3.1 Demodulation bandwidth...............................................................................................25
3.3.2 Stability of measurement results................................................................................... 26
3.3.3 Phase notation in VOR measurements.........................................................................27
4 Measurements and result displays.................................................... 28
4.1 Result displays for VOR/ILS measurements............................................................ 28
4.2 Avionics parameters...................................................................................................33
4.2.1 Signal characteristics.................................................................................................... 33
4.2.2 ILS parameters..............................................................................................................33
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4.2.3 VOR parameters........................................................................................................... 37
4.2.4 Harmonic distortion marker results (markers H1, F1, F2)............................................. 40
5 Configuration........................................................................................42
5.1 Configuration overview.............................................................................................. 42
5.2 Input, output and frontend settings...........................................................................44
5.2.1 Input source settings..................................................................................................... 44
5.2.2 Frequency settings........................................................................................................49
5.2.3 Amplitude settings.........................................................................................................50
5.2.4 Output settings.............................................................................................................. 54
5.3 Trigger settings........................................................................................................... 57
5.4 Data acquisition and detection.................................................................................. 62
5.5 Sweep settings............................................................................................................ 64
Contents
5.6 Demodulation spectrum............................................................................................. 65
6 Analysis................................................................................................ 69
6.1 Display configuration................................................................................................. 69
6.2 Result configuration................................................................................................... 69
6.2.1 Y-Scaling....................................................................................................................... 69
6.2.2 Units.............................................................................................................................. 71
6.3 Markers........................................................................................................................ 72
6.3.1 Individual marker settings............................................................................................. 73
6.3.2 General marker settings................................................................................................77
6.3.3 Marker search settings..................................................................................................78
6.3.4 Marker positioning functions......................................................................................... 79
6.4 Export functions..........................................................................................................80
7 How to perform VOR/ILS measurements...........................................83
8 Optimizing and troubleshooting the measurement.......................... 84
9 Remote commands to perform VOR/ILS measurements................. 87
9.1 Introduction................................................................................................................. 88
9.1.1 Conventions used in descriptions................................................................................. 88
9.1.2 Long and short form...................................................................................................... 89
9.1.3 Numeric suffixes............................................................................................................89
9.1.4 Optional keywords.........................................................................................................89
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9.1.5 Alternative keywords..................................................................................................... 90
9.1.6 SCPI parameters...........................................................................................................90
9.2 Activating VOR/ILS measurements........................................................................... 92
9.3 Selecting the measurement type............................................................................... 96
9.4 Configuring VOR/ILS measurements........................................................................ 97
9.4.1 Input source settings..................................................................................................... 97
9.4.2 Configuring the outputs............................................................................................... 102
9.4.3 Frontend configuration................................................................................................ 103
9.4.4 Triggering measurements........................................................................................... 109
9.4.5 Data acquisition...........................................................................................................116
9.4.6 Configuring the demodulation spectrum......................................................................119
9.5 Configuring and performing sweeps...................................................................... 121
9.6 Analyzing VOR/ILS measurements......................................................................... 123
Contents
9.6.1 Configuring the result display......................................................................................124
9.6.2 Configuring the Y-Axis scaling and units..................................................................... 131
9.6.3 Working with markers..................................................................................................134
9.7 Retrieving results......................................................................................................146
9.7.1 Retrieving numeric results...........................................................................................147
9.7.2 Trace results................................................................................................................157
9.8 Status reporting system........................................................................................... 160
9.8.1 STATus:QUEStionable:SYNC<n> register..................................................................160
9.8.2 Querying the status registers...................................................................................... 161
9.9 Programming examples: performing VOR/ILS measurements............................ 163
9.9.1 Programming example: performing an ILS measurement.......................................... 163
9.9.2 Programming example: performing a VOR measurement.......................................... 165
Annex.................................................................................................. 168
A Abbreviations..................................................................................... 168
List of Commands (Avionics)........................................................... 169
Index....................................................................................................173
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Contents
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R&S®FSW-K15
1 Documentation overview
1.1 Getting started manual
Documentation overview
Service manual
This section provides an overview of the R&S FSW user documentation. Unless specified otherwise, you find the documents on the R&S FSW product page at:
www.rohde-schwarz.com/manual/FSW
Introduces the R&S FSW 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.
1.2 User manuals and help
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.
●
Firmware application manual
Contains the description of the specific functions of a firmware application, including remote control commands. Basic information on operating the R&S FSW is not
included.
The contents of the user manuals are available as help in the R&S FSW. 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.
1.3 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 registered users on the global Rohde & Schwarz
information system (GLORIS):
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1.4 Instrument security procedures
1.5 Printed safety instructions
1.6 Data sheets and brochures
Documentation overview
Application notes, application cards, white papers, etc.
https://gloris.rohde-schwarz.com
Deals with security issues when working with the R&S FSW in secure areas. It is available for download on the Internet.
Provides safety information in many languages. The printed document is delivered with
the product.
The data sheet contains the technical specifications of the R&S FSW. It also lists the
firmware applications 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/FSW
1.7 Release notes and open-source acknowledgment (OSA)
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/FSW
1.8 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/FSW
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2 Welcome to the R&S FSW Avionics (VOR/
Welcome to the R&S FSW Avionics (VOR/ILS) measurements application
Starting the R&S FSW Avionics (VOR/ILS) measurements application
ILS) measurements application
The R&S FSW-K15 is a firmware application that adds functionality to perform
VOR/ILS measurements to the R&S FSW.
The R&S FSW-K15 features:
●
Demodulation of avionics (VOR/ILS) signals
●
Modulation accuracy evaluation
●
Maximum accuracy and temperature stability due to digital down-conversion
●
No evidence of typical errors of analog down-conversion and demodulation like AM
⇔ FM conversion, deviation error, frequency response or frequency drift at DC coupling
This user manual contains a description of the functionality that the application provides, including remote control operation.
General R&S FSW functions
The application-independent functions for general tasks on the R&S FSW are also
available for VOR/ILS measurements and are described in the R&S FSW user manual.
In particular, this comprises the following functionality:
●
Data management
●
General software preferences and information
The latest version is available for download at the product homepage.
For further information see the Rohde & Schwarz Application Note 1MA193: "Aero-
nautical radio navigation measurement solutions".
Installation
You can find detailed installation instructions in the R&S FSW Getting Started manual
or in the Release Notes.
2.1 Starting the R&S FSW Avionics (VOR/ILS) measurements application
The R&S FSW Avionics (VOR/ILS) measurements application adds a new application
to the R&S FSW.
To activate the R&S FSW Avionics (VOR/ILS) measurements application
1. Press the [MODE] key on the front panel of the R&S FSW.
A dialog box opens that contains all operating modes and applications currently
available on your R&S FSW.
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Welcome to the R&S FSW Avionics (VOR/ILS) measurements application
Understanding the display information
2. Select the "Avionics" item.
The R&S FSW opens a new measurement channel for the R&S FSW Avionics
(VOR/ILS) measurements application.
The measurement is started immediately with the default settings. It can be configured
in the VOR/ILS "Overview" dialog box, which is displayed when you select the "Overview" softkey from any menu (see Chapter 5.1, "Configuration overview",
on page 42).
Multiple Measurement Channels and Sequencer Function
When you activate 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 (including the "MultiView") as the measurements are performed. Sequential operation itself is independent of the currently displayed tab.
For details on the Sequencer function see the R&S FSW User Manual.
symbol in the tab label. The result displays of the individual channels
2.2 Understanding the display information
The following figure shows a measurement diagram during analyzer operation. All different information areas are labeled. They are explained in more detail in the following
sections.
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Welcome to the R&S FSW Avionics (VOR/ILS) measurements application
Understanding the display information
1
6
5
1 = Channel bar for firmware and measurement settings
2+6 = Window title bar with diagram-specific (trace) information
3 = Diagram area with marker information
4 = Diagram footer with diagram-specific information, depending on measurement application
5 = Instrument status bar with error messages, progress bar and date/time display
2
3
Channel bar information
In the R&S FSW Avionics (VOR/ILS) measurements application, the R&S FSW shows
the following settings:
Table 2-1: Information displayed in the channel bar in the R&S FSW Avionics (VOR/ILS) measure-
ments application
4
"Ref Level" Reference level
"Att" Mechanical and electronic RF attenuation
"Freq" Center frequency
"RBW" Resolution bandwidth
"Meas Time" Measurement time for data acquisition.
"Meas BW" Demodulation bandwidth
"Meas" Measurement type (ILS/VOR)
"SGL" The sweep is set to single sweep mode.
In addition, the channel bar also displays information on instrument settings that affect
the measurement results even though this is not immediately apparent from the display
of the measured values (e.g. transducer or trigger settings). This information is displayed only when applicable for the current measurement.
For details see the R&S FSW Getting Started manual.
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Welcome to the R&S FSW Avionics (VOR/ILS) measurements application
Understanding the display information
Window title bar information
For diagrams, the header provides the following information:
1 2
4
3
5 6
Figure 2-1: Window title bar information in the R&S FSW Avionics (VOR/ILS) measurements applica-
1 = Window number
2 = Window type
3 = Trace color
4 = Trace number
5 = Detector
6 = Trace mode
tion
Diagram footer information
The diagram footer (beneath the diagram) contains the frequency range.
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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3 Measurement basics
3.1 General information on ILS and VOR/DVOR
Measurement basics
General information on ILS and VOR/DVOR
Some background knowledge on basic terms and principles used in VOR/ILS measurements is provided here for a better understanding of the required configuration settings.
● General information on ILS and VOR/DVOR..........................................................13
● Description of the VOR/ILS measurement demodulator.........................................19
● Impact of specific parameters................................................................................. 25
The following topics summarize some background information on the related avionics
standards. The provided overview information is intended as explanation of the used
terms and does not aim to be comprehensive.
● The instrument landing system (ILS)...................................................................... 13
● VHF omnidirectional radio range (VOR)................................................................. 16
● DVOR (doppler VHF omni-directional range)..........................................................18
3.1.1 The instrument landing system (ILS)
An instrument landing system is used in aircraft during the landing approach to monitor
the correct approach path to the runway.
Using the globally standardized system ILS, an aircraft on a defined glide-path
receives highly accurate position information in reference to the glide-path during landing. This landing path is described by the intersection of a vertical glide-slope level and
a horizontal localizer plane.
Figure 3-1: Basics of the ILS
An ILS system consists of three independent subsystems:
●
A glide slope for vertical guidance.
●
A localizer for horizontal guidance.
●
(optional) marker beacons
● Localizer basics.......................................................................................................14
● Glide slope basics...................................................................................................15
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3.1.1.1 Localizer basics
Measurement basics
General information on ILS and VOR/DVOR
The localizer transmitter is located near the end of the runway (nearest to the start of
the aircraft approach). Typically, horizontally aligned antennas transmit two intersecting
main beams beside one another at carrier frequencies between 108 MHz and
112 MHz. As seen from the approaching aircraft coming in for a landing, the left beam
is usually modulated at 90 Hz and the right beam at 150 Hz.
The information on position is provided after demodulation of the beam signals by evaluating the difference in depth of modulation (DDM).
DDM = m(x90) – m(x150)
The following scenarios are possible:
●
Predominance of the 90 Hz beam: the aircraft is too far to the left and must turn to
the right
●
Predominance of the 150 Hz beam: the aircraft is too far to the right and must turn
to the left
●
The signal strength from both beams is equal: the aircraft is in the center, on the
right course.
Course and clearance signals
The landing path is divided into the region further away from the runway, referred to as
the course, and the runway itself, referred to as the clearance. Localizers are positioned in both areas, however they transmit their ILS signals using different frequencies, one that must travel farther, one for close-up. The frequencies differ only in a few
kilohertz. The aircraft always receives both signals, and cannot (and need not) distinguish the two. However, for test purposes, it can be useful to measure the signals individually.
Morse code identification signal
The localizer not only allows the aircraft to determine its position, it also provides identification of the ILS transmitter. The localizer periodically transmits a Morse code at
1020 Hz which uniquely identifies the transmitter. The receiver thus knows that the ILS
is operating correctly and that it is receiving the correct signal. The glide slope station
does not transmit an identification signal.
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3.1.1.2 Glide slope basics
Measurement basics
General information on ILS and VOR/DVOR
The following description is taken from the Rohde & Schwarz Application Note
1MA193: "Aeronautical radio navigation measurement solutions".
The glide slope transmitter is located near the end of the runway (nearest to the start of
the aircraft approach).
Figure 3-2: Approach navigation using instrument landing system (ILS)
Typically, vertically aligned antennas transmit two intersecting main beams on top of
one another at carrier frequencies between 329 MHz and 335 MHz. The top beam is
usually modulated at 90 Hz and the beam below at 150 Hz.
The information on position is provided after demodulation of the beam signals by evaluating the difference in depth of modulation (DDM). The following scenarios are possible:
●
Predominance of the 90 Hz beam: the aircraft is too high and must descend
●
Predominance of the 150 Hz beam: the aircraft is too low and needs to climb
●
The signal strength from both beams is equal: the aircraft is in the center, on the
right course.
If there is a predominance of the 90 Hz beam, then the aircraft is too high and must
descend. A predominant 150 Hz means that the aircraft is too low and needs to climb.
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3.1.2 VHF omnidirectional radio range (VOR)
Measurement basics
General information on ILS and VOR/DVOR
Very high frequency (VHF) omnidirectional radio range (VOR) is a radio navigation system for short and medium distance navigation. The VOR radio navigation aid supplies
the aircraft with directional information, angle information relative to the magnetic north
from the site of the beacon. Thus, it helps aircraft to determine their position and stay
on course. The range covered by a VOR station is ideally a circle around the VOR station with a radius depending on the flight altitude.
A VOR system consists of a ground transmission station and a VOR receiver on board
the aircraft.
Ground transmitter
The transmitter stations operate at VHF frequencies of 108 MHz to 118 MHz, with the
code identification (COM/ID) transmitting on a modulation tone of 1.020 kHz. It emits
two types of signals:
●
An omnidirectional reference signal (REF) that can consist of two parts:
– 30 Hz frequency modulated (FM) sine wave on subcarrier 9.96 kHz from ampli-
tude modulation (AM) carrier
– 1020 Hz AM modulated sine wave Morse code
●
A directional positioning signal, variable (VAR): 30 Hz AM modulated sine waves
with variable phase shift
VOR receiver
The VOR receiver obtains the directional information by measuring the phase difference of two 30 Hz signals transmitted by the beacon. A conventional VOR station
(CVOR) transmits with a rotating antenna. From the rotation, a sine wave AM signal
arises in the receiver, whose phase position depends on the present angle of rotation.
The rotation frequency of the antenna sets the modulation frequency at 30 Hz.
Instead of using a rotating antenna, DVOR stations (Doppler) divide the circumference
of the antenna into 48 or 50 segments, covering each segment by its own antenna.
Each antenna transmits the unmodulated subcarrier from one antenna to the next, so
that the signal completes the round trip 30 times per second.
To determine the radial, the phase difference to a reference phase must be measured.
This reference phase must be independent of the rotation of the antenna. Thus, it is
modulated with a frequency deviation of 480 Hz in FM onto a secondary carrier with
9.96 kHz. It is then emitted over a separate antenna with a round characteristic.
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Measurement basics
General information on ILS and VOR/DVOR
Figure 3-3: Basics of the VOR phase angles (Φ) depending on the azimuth angle (Θ)
The frequency modulated secondary carrier for the reference phase is itself again
modulated in AM on the RF carrier of the VOR station. In addition to the signals necessary for navigation, a Morse code with 1020 Hz can be transmitted on the VOR carrier.
Also, speech in the usual AF from 300 Hz to 3.3 kHz can be transmitted. Often the
voice channel of a VOR station is used for the transmission of ATIS (Automatic Terminal Information Service) messages. The Morse code can be used to identify the VOR
station, similar to the "Morse code identification signal" on page 14 in the ILS signal.
The spectrum of a VOR signal is therefore composed of the carrier and three modulated components.
Figure 3-4: Example of the VOR Spectrum
The identical modulation degree m = 0.3 for all three components was selected in
ICAO annex-10 [63] such that the total signal still contains 10% modulation reserve.
The carrier is therefore not suppressed at any time. The 9960 Hz reference carrier is
FM modulated with 480 Hz deviation. The VOR signal generation as under ICAO is
shown below.
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3.1.3 DVOR (doppler VHF omni-directional range)
Measurement basics
General information on ILS and VOR/DVOR
Figure 3-5: Basics of the VOR signal generation
Like a VOR beacon, a DVOR beacon transmits an RF signal in which the two phase
angles are coded. From the difference between these phases, the receiver can calculate its position in reference to the DVOR. In contrast to the VOR signal, the meaning
of the reference and azimuth-dependent phase is opposite. This means that the reference phase is no longer emitted in FM through the secondary carrier. Instead, the
30 Hz reference signal is emitted in AM from a fixed antenna.
In DVOR the azimuth-dependent phase is generated using the Doppler effect. The
Doppler effect is such that the receiving frequency frx increases when there is radial rel-
ative movement of a receiver with a speed vx towards the transmitter. Correspondingly,
it decreases when there is movement away from the transmitter.
The following figure shows the 50 circularly arranged single antennas of a DVOR station. The secondary carrier to be transmitted on (+9.96 kHz carrier) is distributed using
an electronic multiplexer on the circularly arranged antenna. Thus, the transmission
signal seems to revolve at 30 Hz in the circle.
Figure 3-6: Basics of a DVOR system
The circles shown in the above figure symbolize radial transmitters. The transmission
antenna in the center of the circle (M) transmits the reference phase in the form of the
30 Hz AM modulated carrier and the identifier of the station. The Doppler shift corresponds to the FM deviation.
In practice both sidebands of the secondary carrier (carrier + 9.96 kHz and carrier -
9.96 kHz) are created separately and fed into the antenna array spatially displaced by
180°. Therefore two super-imposed individual antennas are emitting at one period in
time, each being one sideband of the total signal. In the far field, there is the effect of
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Measurement basics
Description of the VOR/ILS measurement demodulator
an FM signal on the receiver. One sideband component always increases in frequency
due to the Doppler effect, while the other component decreases in frequency. The reason for this complex method of signal generation lies in the high accuracy which can
be obtained for the azimuth-dependent phase.
Figure 3-7: Basics of the DVOR signal generation
3.2 Description of the VOR/ILS measurement demodulator
The following chapter describes the functions of the VOR/ILS measurement demodulator in the R&S FSW Avionics (VOR/ILS) measurements application.
By sampling (digitization) already at the IF and digital down-conversion to the baseband (I/Q), the demodulator achieves maximum accuracy and temperature stability.
There is no evidence of typical errors of an analog down-conversion and demodulation
like AM ⇔ FM conversion, deviation error, frequency response or frequency drift at DC
coupling.
3.2.1 Circuit description - block diagrams
Figure 3-8: Block diagram of analyzer signal processing
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3.2.2 ILS demodulator
Measurement basics
Description of the VOR/ILS measurement demodulator
Figure 3-8 shows the analyzer's hardware from the IF to the processor. The A/D con-
verter samples the IF.
Lowpass filtering and reduction of the sampling rate follow the down-conversion to the
complex baseband. The decimation depends on the selected demodulation bandwidth.
Useless over-sampling at narrow bandwidths is avoided, saving calculating time and
increasing the maximum recording time.
The software demodulator runs on the main processor of the analyzer. The demodulation process is shown below. All calculations are performed simultaneously with the
same I/Q data set.
Figure 3-9: Block diagram of ILS software demodulator
The ILS demodulation basically comprises two bandpass filters with 90 Hz and 150 Hz
center frequencies. To meet the required selectivity with a reasonable filter order, the
AM signal must be decimated in frequency before filtering.
The optional ID signal is separated by a bandpass filter with a frequency range from
300 Hz to 4000 Hz.
A Morse decoder detects and decodes the ON and OFF periods in the identifier signal.
AM modulation depth
To obtain the AM depth, a lowpass filter must calculate the mean carrier power, while
suppressing all other signal components. The mean carrier power is then used to nor-
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Measurement basics
Description of the VOR/ILS measurement demodulator
malize the instantaneous magnitude of the I/Q signal. The result is the AM modulation
depth signal vs. time.
The following AM depths and their derivatives are calculated:
●
"Depth90": Modulation depth of the 90 Hz signal
●
"Depth
●
"DepthID": Modulation depth of the identification/voice signal.
": Modulation depth of the 150 Hz signal
150
– For a demodulation bandwidth of 12.5 kHz or larger: from 300 Hz to 4 kHz.
– For a demodulation bandwidth of 3.2 kHz: from 300 Hz to 1.6 kHz
– For a demodulation bandwidth of 800 Hz: not supported
●
"Sum90+150": Modulation depth of the signal containing both the 90 Hz and the
150 Hz component. Measured as peak-to-peak value after interpolating the signal.
●
"SDM90,150": Sum of modulation depths: "Depth90" + "Depth150"
●
"DDM90,150": Difference in modulation depths: "Depth90" - "Depth150"
AF frequencies
The following AF frequencies are calculated:
●
"Freq90": Modulating frequency of the 90 Hz signal
●
"Freq150": Modulating frequency of the 150 Hz signal
●
"FreqID": Modulating frequency of the identification/voice signal.
– For a demodulation bandwidth of 12.5 kHz or larger: from 300 Hz to 4 kHz.
– For a demodulation bandwidth of 3.2 kHz: from 300 Hz to 1.6 kHz
– For a demodulation bandwidth of 800 Hz: not supported
Phase angle 90/150 Hz
The phase angle is calculated using the estimated phases and frequencies of the
90 Hz and the 150 Hz signal. It describes the phase of the 150 Hz signal at the time
the 90 Hz signal crosses zero. If both involved frequencies have their ideal 3 to 5 ratio
the phase angle is valid. Phase angles exceeding ± 60° lead to ambiguous results. If
one of the two involved signals is turned off or if the frequency ratio is not 3 to 5, this
result does not make sense.
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Measurement basics
Description of the VOR/ILS measurement demodulator
Figure 3-10: Phase angle ambiguity
Example: ILS phase difference of 40 degrees
When the 90 Hz signal crosses zero, the 150 Hz signal has the following phase values:
-80 deg, +160 deg, +40 deg, -80 deg, etc.
If you add or subtract 120 degrees, the ambiguity is eliminated: all values become 40
degrees.
ILS distortion
The ILS software demodulator also analyzes AM AF distortions. The AM modulation
depth vs time signal is processed by an FFT, using a user-defined resolution bandwidth. The trace is displayed in the "Modulation Spectrum" display. The K2, K3 and
THD results of the AM components are calculated based on the FFT trace and the estimated modulation frequencies.
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3.2.3 VOR demodulator
Measurement basics
Description of the VOR/ILS measurement demodulator
Figure 3-11: Block diagram of the VOR software demodulator
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Measurement basics
Description of the VOR/ILS measurement demodulator
The VOR signal contains three AM modulated components that must be separated in a
first step:
●
Rotational signal (30 Hz)
●
Identification/voice part (300 Hz to 4 kHz)
●
FM modulated carrier (9960 Hz ± 700 Hz)
To obtain the AM depth, a lowpass filter must calculate the mean carrier power, while
suppressing all other signal components. The mean carrier power is then used to normalize the instantaneous magnitude of the I/Q signal. The result is the AM modulation
depth signal vs. time. The three AM components are separated using bandpass filters
covering the individual frequency ranges.
A Morse decoder detects and decodes the ON and OFF periods in the identifier signal.
The separated FM modulated carrier is passed through an FM demodulator. The FM
carrier frequency (nominal 9960 Hz) is calculated as the average output value of the
FM demodulator. To obtain the 30 Hz reference signal, the FM demodulator output is
filtered by the same narrow 30 Hz bandpass as the 30 Hz AM rotational component.
FM deviation is calculated using the estimated magnitude of the 30 Hz reference signal.
The azimuth is calculated as the phase difference of the 30 Hz reference signal and
the 30 Hz rotational signal.
VOR distortion
In the VOR software demodulator two kinds of signals are analyzed regarding distortions:
●
AM Distortion: The AM modulation depth vs time signal is processed by an FFT,
with a user-defined resolution bandwidth. The trace is displayed in the "Modulation
Spectrum" display. The K2, K3 and THD results of the AM components are calculated based on the FFT trace and the estimated modulation frequencies.
●
FM Distortion: The FM modulation depth vs time signal is processed by an FFT,
using a resolution bandwidth automatically set by the application. You cannot view
the resulting trace. The K2, K3 and THD results of the FM components are calculated based on the FFT trace and the estimated modulation frequencies.
3.2.3.1 AM modulation depth
To obtain the AM depth, a lowpass filter must calculate the mean carrier power, while
suppressing all other signal components. The mean carrier power is then used to normalize the instantaneous magnitude of the I/Q signal. The result is the AM modulation
depth signal versus time. It is then used to calculate the following AM modulation
depths:
●
Depth
●
Depth
●
DepthID: AM modulation depth of the identification/voice signal
: AM modulation depth of the FM carrier, typically at 9960 Hz
9960
: AM modulation depth of the 30 Hz rotational signal
AM30
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3.2.3.2 FM modulation depth
Measurement basics
Impact of specific parameters
The FM deviation Devia
(typically 480 Hz) is calculated by estimating the magni-
FM30
tude of the FM demodulated 30 Hz reference signal.
3.2.3.3 Azimuth (phase difference at 30 hz)
The phases of both the 30 Hz FM and 30 Hz AM signal are estimated at exactly the
same time instant. The azimuth (Phase FM-AM) is calculated as the phase difference
between the two.
3.2.3.4 AF frequencies
In the VOR demodulator the AF frequencies are calculated:
●
Freq
●
Freq
●
FreqID: voice / identification; From 300 Hz to 4 kHz, typically 1020 Hz
●
Freq
: 30 Hz Rotational-signal (AM)
AM30
: 30 Hz Reference-signal (FM)
FM30
: The carrier frequency of the FM carrier, typically 9960 Hz; Calculated as
9960
mean value of the FM demodulator output
3.3 Impact of specific parameters
● Demodulation bandwidth.........................................................................................25
● Stability of measurement results.............................................................................26
● Phase notation in VOR measurements...................................................................27
3.3.1 Demodulation bandwidth
The R&S FSW Avionics (VOR/ILS) measurements application captures I/Q data using
digital filters with quasi-rectangular amplitude responses. The demodulation bandwidth
defines the width of the filter's flat passband. This is not the 3 dB bandwidth, but the
useful bandwidth which is distortion-free with regard to phase and amplitude.
Small demodulation bandwidths have the following advantages:
●
Lower sample rate, less IQ data, higher measurement speed
●
Only the signal of interest is captured, no adjacent signals and less noise captured,
better SNR
Large demodulation bandwidths have the following advantages:
●
A high carrier frequency offset of the DUT is no longer critical because the whole
spectrum of the signal still falls in the filter's passband. FM to AM conversion is
avoided (VOR mode)
●
The "Modulation Spectrum" display allows for a wider span, showing harmonics of
a higher order
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Measurement basics
Impact of specific parameters
It is recommended that you use the automatic configuration of the demodulation bandwidth, which applies the following settings:
●
ILS
DBW = 12.5 kHz, to capture the full identifier signal
●
VOR
DBW = 25 kHz, to capture the 9.96 kHz signal
If the demodulation bandwidth setting is changed, some demodulation results may not
be available due to bandwidth limitations. For harmonic distortion measurement, the
highest measured harmonic signal may be limited due to the demodulation bandwidth
(see also "Distortion Max Frequency" on page 67).
The following tables show the relationship between the available demodulation bandwidths and measurement times for the different measurements.
Table 3-1: Available demodulation bandwidths and measurement times for ILS measurements
Demodulation BW Meas time min Meas time max Meas time default
800 Hz 0.1 sec 133 sec 1 sec
3.2 KHz 0.1 sec 33.4 sec 1 sec
12.5 KHz 0.1 sec 8.356 sec 1 sec
50 KHz 0.1 sec 8.356 sec 1 sec
100 KHz 0.1 sec 8.356 sec 1 sec
Table 3-2: Available demodulation bandwidths and measurement times for VOR measurements
Demodulation BW Meas time min Meas time max Meas time default
25 KHz 0.1 sec 30 sec 1 sec
50 KHz 0.1 sec 30 sec 1 sec
100 KHz 0.1 sec 30 sec 1 sec
3.3.2 Stability of measurement results
The stability of the algorithms used to estimate the modulation depths and Azimuth rely
on a sufficient amount of data. This is achieved if at least five periods of the 30 Hz
basic modulation frequency are recorded. Since the R&S FSW Avionics (VOR/ILS)
measurements application automatically compensates for filter settling times internally,
a measurement time of approximately 200 ms is required.
Note that the precision as specified in the data sheet is guaranteed only if the 30 Hz
AM rotational component can be identified properly in the VOR analysis case.
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3.3.3 Phase notation in VOR measurements
Measurement basics
Impact of specific parameters
In VOR measurements, the phase can be provided using two different notations, indicated in the following illustration:
Figure 3-12: Phase notation in VOR measurements
Phase is always counted counter-clockwise, starting at the reference.
The reference depends on the selected notation:
●
FROM: North direction at the VOR beacon
●
TO: North direction at the receiver/ aircraft
To convert one notation to the other, use the following equation:
PhaseTO = Phase
+ 180 deg
FROM
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4 Measurements and result displays
Measurements and result displays
Result displays for VOR/ILS measurements
The R&S FSW Avionics (VOR/ILS) measurements application provides two different
measurements to determine the parameters described by the VOR/ILS specifications.
ILS measurement
The R&S FSW Avionics (VOR/ILS) measurements application demodulates the AM
components of the ILS signal at the RF input and calculates characteristic parameters
such as the modulation depth and frequency or phase for specific components. Furthermore, an FFT is performed on all components of the AF signal. The resulting AF
spectrum allows you to measure the required components and their distortions (harmonics).
VOR measurement
The R&S FSW Avionics (VOR/ILS) measurements application demodulates the AM
and FM components of the VOR signal at the RF input. Then it calculates characteristic parameters, such as the modulation depth, and frequency or phase for specific
components and subcarriers. The VOR phase, i.e. the phase difference between the
AM and FM signal components, is also calculated. Furthermore, an FFT is performed
on all components of the AF signal. The resulting AF spectrum allows you to measure
the required components and their distortions (harmonics).
Selecting the measurement type
To select a different measurement type, do one of the following:
●
Select the "Overview" softkey. In the "Overview", select the "Select Measurement"
button. Select the required measurement.
●
Press the [MEAS] key. In the "Select Measurement" dialog box, select the required
measurement.
Remote command:
CALCulate<n>:AVIonics[:STANdard] on page 96
● Result displays for VOR/ILS measurements...........................................................28
● Avionics parameters................................................................................................33
4.1 Result displays for VOR/ILS measurements
Access: "Overview" ≥ "Display Config"
The captured VOR/ILS signal can be displayed using various evaluation methods. All
evaluation methods available for VOR/ILS measurements are displayed in the evaluation bar in SmartGrid mode.
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Measurements and result displays
Result displays for VOR/ILS measurements
For details on working with the SmartGrid, see the R&S FSW Getting Started manual.
By default, the ILS measurement results are displayed in the following windows:
●
Signal Summary
●
Result Summary
●
Modulation Spectrum
The following evaluation methods are available for VOR/ILS measurements:
Signal Summary............................................................................................................29
Result Summary............................................................................................................29
Distortion Summary.......................................................................................................30
Modulation Spectrum.................................................................................................... 31
Marker Table................................................................................................................. 32
Signal Summary
Displays information on the input signal settings and measured values in one table.
A bargraph visualizes the signal strength compared to the current level settings. The
peak power measured during the current or most recent measurement is indicated by a
vertical yellow line in the graph. This is useful to detect underload or overload conditions at a glance.
Figure 4-1: Signal summary for ILS signal
For details on individual parameters, see Chapter 4.2.1, "Signal characteristics",
on page 33.
Remote command:
LAY:ADD? '1',RIGH,SSUM, see LAYout:ADD[:WINDow]? on page 125
Results:
CALCulate<n>:AVIonics:FERRor[:RESult]? on page 150
CALCulate<n>:AVIonics:RFFRequency[:RESult]? on page 151
CALCulate<n>:AVIonics:CARRier[:RESult]? on page 149
Result Summary
Displays the numerical measurement results for the demodulated signal components.
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Measurements and result displays
Result displays for VOR/ILS measurements
Figure 4-2: Result summary for ILS signal
Figure 4-3: Result summary for VOR signal
The scale bar at the bottom of the table provides a quick overview at a glance. It indicates the difference in depth of modulation (DDM) for ILS, and the azimuth (FROM/TO
phase) for VOR measurements graphically.
For details on individual parameters, see Chapter 4.2, "Avionics parameters",
on page 33.
Note: If the result display is too narrow to display the complete table, the THD, K2 and
K3 are hidden. Increase the width of the window to display the complete table.
Remote command:
LAY:ADD? '1',RIGH,RSUM, see LAYout:ADD[:WINDow]? on page 125
Results:
Chapter 9.7, "Retrieving results", on page 146
Distortion Summary
Displays the results of the harmonic distortion measurement.
Figure 4-4: Distortion summary for ILS signal
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Measurements and result displays
Result displays for VOR/ILS measurements
Figure 4-5: Distortion summary for VOR signal
For details on individual parameters, see Chapter 4.2, "Avionics parameters",
on page 33.
Remote command:
LAY:ADD? '1',RIGH,DSUM, see LAYout:ADD[:WINDow]? on page 125
Results:
Chapter 9.7, "Retrieving results", on page 146
Modulation Spectrum
Displays the FFT spectrum of the AF input signal.
Figure 4-6: Modulation spectrum for a VOR signal
Two fixed markers (H1, F1) are always active and displayed in the "Modulation Spectrum" diagram. F1 indicates the currently selected Fundamental Frequency for distortion measurement, as well as the measured power level. A third marker, F2, is set to a
second fundamental frequency for ILS measurements on the 90 Hz + 150 Hz components only. H1 indicates the currently selected frequency for distortion measurement
(see Harmonic Frequency). Furthermore, the results include the power measured at
that frequency, and the distortion at this frequency in relation to the power at the fundamental frequency.
Note: The marker results can be displayed in a separate Marker Table, if configured
accordingly (see "Marker Table Display" on page 77).
The results of the F1, F2 markers are only displayed in the Marker Table.
The distortion for the H1 marker is only displayed in the "Modulation Spectrum" diagram.
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Measurements and result displays
Result displays for VOR/ILS measurements
As opposed to common markers, F1 and F2 markers cannot be repositioned manually,
for example by dragging them on the screen. Their position is automatically defined by
the Harmonic Frequency and Fundamental Frequency settings, respectively (see "Dis-
tortion" on page 67). These markers cannot be deactivated or configured.
Remote command:
LAY:ADD? '1',RIGH,MSP, see LAYout:ADD[:WINDow]? on page 125
Results:
TRACe<n>[:DATA]? on page 157
CALCulate<n>:AVIonics:SHD:FREQuency on page 152
CALCulate<n>:AVIonics:SHD:RESult? on page 153
CALCulate<n>:AVIonics:SHD[:STATe] on page 153
Marker Table
Displays a table with the current marker values for the active markers.
This table can be displayed automatically if configured accordingly (see "Marker Table
Display" on page 77).
Tip: To navigate within long marker tables, simply scroll through the entries with your
finger on the touchscreen.
Note: Two fixed markers (H1, F1) are always active and displayed in the "Marker
Table". F1 indicates the currently selected Fundamental Frequency for distortion measurement, as well as the measured power level. A third marker, F2, is set to a second
fundamental frequency for ILS measurements on the 90 Hz + 150 Hz components
only. H1 indicates the currently selected frequency for distortion measurement (see
Harmonic Frequency) and the power measured at that frequency.
The distortion at this frequency (measured as the power in relation to the power at the
fundamental frequency) is indicated as an additional marker result in the Modulation
Spectrum.
As opposed to common markers, F1 and F2 markers cannot be repositioned manually,
for example by dragging them on the screen. Their position is automatically defined by
the Harmonic Frequency and Fundamental Frequency settings, respectively (see "Dis-
tortion" on page 67). These markers cannot be deactivated or configured.
Remote command:
LAY:ADD? '1',RIGH, MTAB, see LAYout:ADD[:WINDow]? on page 125
Results:
CALCulate<n>:MARKer<m>:X on page 139
CALCulate<n>:MARKer<m>:Y? on page 146
Results:
CALCulate<n>:AVIonics:SHD:FREQuency on page 152
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4.2 Avionics parameters
4.2.1 Signal characteristics
Measurements and result displays
Avionics parameters
CALCulate<n>:AVIonics:SHD:RESult? on page 153
CALCulate<n>:AVIonics:SHD[:STATe] on page 153
The VOR/ILS measurements capture the I/Q data of the VOR/ILS signal and determine
the following I/Q parameters in a single measurement:
● Signal characteristics.............................................................................................. 33
● ILS parameters........................................................................................................33
● VOR parameters..................................................................................................... 37
● Harmonic distortion marker results (markers H1, F1, F2).......................................40
The following parameters characterize the measured signal in general and are available for all VOR/ILS measurements.
RF Frequency............................................................................................................... 33
Carrier Offset.................................................................................................................33
RF Level........................................................................................................................33
RF Frequency
Measured RF (=carrier) frequency of the signal
Remote command:
CALC:AVI:RFFR?
Carrier Offset
Difference between measured frequency and frequency setting ("Center Frequency"
on page 49)
Positive value if the signal's carrier frequency is higher than expected
Remote command:
CALC:AVI:FERR?
RF Level
Measured RF signal level
Remote command:
CALC:AVI:CARR?
4.2.2 ILS parameters
For ILS measurements, the following parameters are determined.
90 Hz AM depth............................................................................................................ 34
90 Hz AM frequency......................................................................................................34
90 Hz AM THD..............................................................................................................34
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Avionics parameters
150 Hz AM depth.......................................................................................................... 34
150 Hz AM frequency....................................................................................................34
150 Hz AM THD............................................................................................................34
90+150 Hz AM depth.................................................................................................... 35
90+150 Hz AM phase....................................................................................................35
90+150 Hz AM THD......................................................................................................35
Voice / IDENT AM depth...............................................................................................35
Voice / IDENT AM frequency........................................................................................ 35
Voice / IDENT AM THD.................................................................................................35
Ident Code.....................................................................................................................35
SDM.............................................................................................................................. 36
ILS DDM........................................................................................................................36
K2..................................................................................................................................36
K3..................................................................................................................................36
THD total.......................................................................................................................36
90 Hz AM depth
AM modulation depth of 90 Hz ILS component
Remote command:
CALC:AVI:AM:DEPT? '90'
90 Hz AM frequency
AF frequency of 90 Hz ILS component
Remote command:
CALC:AVI:AM:FREQ? '90'
90 Hz AM THD
Total harmonic distortion of 90 Hz ILS component
(THD = the ratio of the sum of the powers of all harmonic components to the power of
the fundamental frequency)
The unit depends on the Distortion setting.
Remote command:
CALC:AVI:THD:RES? '90'
150 Hz AM depth
AM modulation depth of 150 Hz ILS component
Remote command:
CALC:AVI:AM:DEPT? '150'
150 Hz AM frequency
AF frequency of 150 Hz ILS component
Remote command:
CALC:AVI:AM:FREQ? '150'
150 Hz AM THD
Total harmonic distortion of 150 Hz ILS component
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Measurements and result displays
Avionics parameters
Remote command:
CALC:AVI:THD:RES? '150'
90+150 Hz AM depth
(Remote query only)
Total AM modulation depth of the 90 Hz and the 150 Hz components, taking the phase
between the components into account.
Remote command:
CALC:AVI:AM:DEPT? '90+150'
90+150 Hz AM phase
Phase angle measurement between 90 Hz and 150 Hz AM signal (90 Hz = reference
signal); measurement range: ±60 degrees
Remote command:
CALC:AVI:PHAS?
90+150 Hz AM THD
Total harmonic distortion of the 90 Hz and the 150 Hz components
The unit depends on the Distortion setting.
Remote command:
CALC:AVI:THD:RES? '90+150'
Voice / IDENT AM depth
AM Modulation depth of identifier signal and speech band (300 Hz to 4 kHz) without
influence by the actual ILS signal components
Remote command:
CALC:AVI:AM:DEPT? 'ID'
Voice / IDENT AM frequency
AM frequency of identifier signal and speech band (300 Hz to 4 kHz) without influence
by the actual ILS signal components
Remote command:
CALC:AVI:AM:FREQ? 'ID'
Voice / IDENT AM THD
Total harmonic distortion of the identifier signal component
The unit depends on the Distortion setting.
Remote command:
CALC:AVI:THD:RES? 'ID'
Ident Code
Morse code of identifier
Remote command:
CALC:AVI:AM:CODE?
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Measurements and result displays
Avionics parameters
SDM
Sum in Depth of Modulation (SDM); arithmetic sum of the modulation depth of the
90 Hz and the 150 Hz components without any influence of the phase between the
components.
Remote command:
CALC:AVI:SDM?
ILS DDM
Difference in depth of modulation (DDM) between 90 Hz and 150 Hz AM signal (m
– m
150 Hz
)
The unit depends on the ILS DDM setting.
Remote command:
CALC:AVI:DDM?
K2
Relative amplitude of an AF signal's second harmonic, calculated as:
<amplitude of second harmonic> / <amplitude of fundamental>
For 90 Hz + 150 Hz:
90 Hz
<mean amplitude of second harmonics> / <mean amplitude of fundamentals>
The unit depends on the Distortion setting.
Remote command:
CALC:AVI:THD:K2? '90'
CALC:AVI:THD:K2? '150'
CALC:AVI:THD:K2? '90+150'
CALC:AVI:THD:K2? 'ID'
K3
Relative amplitude of an AF signal's third harmonic, calculated as:
<amplitude of third harmonic> / <amplitude of fundamental>
For 90 Hz + 150 Hz:
<mean amplitude of third harmonics> / <mean amplitude of fundamentals>
The unit depends on the Distortion setting.
Remote command:
CALC:AVI:THD:K3? '90'
CALC:AVI:THD:K3? '150'
CALC:AVI:THD:K3? '90+150'
CALC:AVI:THD:K3? 'ID'
THD total
Total harmonic distortion relative to the fundamental frequency. Only distortions at frequencies below the specified Distortion Max Frequency parameter are taken into
account in the following calculations.
For the 90 Hz, 150 Hz, and identification signal:
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%100*
f1A
...f4Af3Af2A
THD
222
Measurements and result displays
Avionics parameters
A = measured modulation depth for the specified harmonic on a linear scale
f = fundamental frequency
For the 90 Hz + 150 Hz:
The nominator contains all frequencies N* 30 Hz (except 90 Hz, 150 Hz). The denomi-
nator is the average of the modulation depth at 90 Hz and at 150 Hz.
The unit depends on the Distortion setting.
Remote command:
CALC:AVI:THD:RES? '90'
CALC:AVI:THD:RES? '150'
CALC:AVI:THD:RES? '90+150'
CALC:AVI:THD:RES? 'ID'
4.2.3 VOR parameters
For VOR measurements, the following parameters are determined.
30 Hz AM depth............................................................................................................ 37
30 Hz AM frequency......................................................................................................37
30 Hz AM THD..............................................................................................................38
9.96 kHz AM depth........................................................................................................38
9.96 kHz AM frequency.................................................................................................38
9.96 kHz AM THD......................................................................................................... 38
30 Hz FM depth.............................................................................................................38
30 Hz FM frequency......................................................................................................38
30 Hz FM THD.............................................................................................................. 38
VOICE / IDENT AM depth.............................................................................................38
VOICE / IDENT AM frequency......................................................................................38
VOICE / IDENT AM THD.............................................................................................. 39
VOR Phase................................................................................................................... 39
K2..................................................................................................................................39
K3..................................................................................................................................39
THD...............................................................................................................................39
30 Hz AM depth
AM modulation depth of 30 Hz AM rotational signal
Remote command:
CALC:AVI:AM:DEPT? '30'
30 Hz AM frequency
AF frequency of 30 Hz AM rotational signal
Remote command:
CALC:AVI:AM:FREQ? '30'
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Measurements and result displays
Avionics parameters
30 Hz AM THD
Total harmonic distortion of 30 Hz component
The unit depends on the Distortion setting.
Remote command:
CALC:AVI:THD:RES? '30'
9.96 kHz AM depth
AM modulation depth of 9.96 kHz subcarrier
Remote command:
CALC:AVI:AM:DEPT? '9960'
9.96 kHz AM frequency
Mean carrier frequency of the FM modulated subcarrier, typically at 9.96 kHz
Remote command:
CALC:AVI:AM:FREQ? '9960'
9.96 kHz AM THD
Total harmonic distortion of 9.96 kHz component (FM carrier)
The unit depends on the Distortion setting.
Remote command:
CALC:AVI:THD:RES? '9960'
30 Hz FM depth
FM frequency deviation of 30 Hz subcarrier
Remote command:
CALC:AVI:FM?
30 Hz FM frequency
AF frequency of the 30 Hz reference signal
Remote command:
CALC:AVI:FM:FREQ?
30 Hz FM THD
Total harmonic distortion of 30 Hz component
The unit depends on the Distortion setting.
Remote command:
CALC:AVI:THD:RES? '30FM'
VOICE / IDENT AM depth
AM Modulation depth of identifier signal and speech band (300 Hz to 4 kHz)
Remote command:
CALC:AVI:AM:DEPT? 'ID'
VOICE / IDENT AM frequency
AM frequency of identifier signal and speech band (300 Hz to 4 kHz)
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Measurements and result displays
Avionics parameters
Remote command:
CALC:AVI:AM:FREQ? 'ID'
VOICE / IDENT AM THD
Total harmonic distortion of the identifier signal component
The unit depends on the Distortion setting.
Remote command:
CALC:AVI:THD:RES? 'ID'
VOR Phase
Phase angle measurement between 30 Hz AM & 30 Hz FM demodulated signal (in
degrees)
Note the effect of the VOR Phase setting on the results!
Remote command:
CALC:AVI:PHAS?
K2
Relative amplitude of an AF signal's second harmonic, calculated as:
<amplitude of second harmonic> / <amplitude of fundamental>
The unit depends on the Distortion setting.
Remote command:
CALC:AVI:THD:K2? '30'
CALC:AVI:THD:K2? '30FM'
CALC:AVI:THD:K2? '9960'
CALC:AVI:THD:K2? 'ID'
K3
Relative amplitude of an AF signal's third harmonic, calculated as:
<amplitude of third harmonic> / <amplitude of fundamental>
The unit depends on the Distortion setting.
Remote command:
CALC:AVI:THD:K3? '30'
CALC:AVI:THD:K3? '30FM'
CALC:AVI:THD:K3? '9960'
CALC:AVI:THD:K3? 'ID'
THD
Total harmonic distortion relative to the fundamental frequency.
The unit depends on the Distortion setting.
For AM modulated components: Only distortions at frequencies below the specified
Distortion Max Frequency parameter are taken into account in the following calcula-
tions.
For the 30 Hz AM rotational signal, 30 Hz reference signal, FM carrier at 9960 , and
identification signal:
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%100*
f1A
...f4Af3Af2A
THD
222
Measurements and result displays
Avionics parameters
A = measured modulation depth for the specified harmonic on a linear scale
f = fundamental frequency
Note: For the FM carrier at 9960 Hz, the distortion results are calculated slightly differ-
ently. Since it is an FM spectrum consisting of many lines, the harmonics and fundamentals cannot be calculated on distinct frequencies. Thus, the R&S FSW Avionics
(VOR/ILS) measurements application integrates the values over a bandwidth centered
around the estimated FM carrier frequency, or N times that frequency. The integration
bandwidth is derived from the estimated FM carrier deviation and increases more and
more with each next harmonic, as the bandwidth of the distortion products also broadens.
Remote command:
CALC:AVI:THD:RES? '90'
CALC:AVI:THD:RES? '150'
CALC:AVI:THD:RES? '90+150'
CALC:AVI:THD:RES? 'ID'
4.2.4 Harmonic distortion marker results (markers H1, F1, F2)
Three fixed markers (H1, F1, F2) are always active and displayed in the "Modulation
Spectrum" diagram. They are used to calculate the harmonic distortion at specified frequencies.
F1, (F2)......................................................................................................................... 40
H1..................................................................................................................................40
DIST..............................................................................................................................40
F1, (F2)
Fundamental frequency
Reference frequency for harmonic distortion measurement (or frequencies for distor-
tion measurement on multiple signal components)
Remote command:
CALCulate<n>:AVIonics:THD:FREQuency:FUNDament
H1
Harmonic frequency
Frequency at which harmonic distortion is measured; position of marker H1
Remote command:
CALCulate<n>:AVIonics:SHD:FREQuency
DIST
Distortion at harmonic frequency (H1)
Calculated as the relative difference between modulation at harmonic frequency and
modulation at fundamental frequency (=H1
mod
/F1
mod
)*100
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Measurements and result displays
Avionics parameters
Remote command:
CALCulate<n>:AVIonics:SHD:RESult? on page 153
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5 Configuration
Configuration
Configuration overview
Access: [MODE] > "Avionics"
VOR/ILS measurements require a special application on the R&S FSW.
The settings required to configure each of these measurements are described here.
When you switch a measurement channel to the R&S FSW Avionics (VOR/ILS) measurements application the first time, a set of parameters is passed on from the currently active application. After initial setup, the parameters for the measurement channel are stored upon exiting and restored upon re-entering the channel. Thus, you can
switch between applications quickly and easily.
When you activate a measurement channel in the R&S FSW Avionics (VOR/ILS) measurements application, a VOR measurement for the input signal is started automatically with the default configuration. The "Avionics" menu is displayed and provides
access to the most important configuration functions.
Exporting I/Q Data
Access:
The I/Q data captured by the R&S FSW Avionics (VOR/ILS) measurements application
can be exported for further analysis in external applications.
For details on exporting I/Q data, see the R&S FSW I/Q Analyzer and I/Q Input User
Manual.
● Configuration overview............................................................................................42
● Input, output and frontend settings..........................................................................44
● Trigger settings....................................................................................................... 57
● Data acquisition and detection................................................................................62
● Sweep settings........................................................................................................64
● Demodulation spectrum.......................................................................................... 65
5.1 Configuration overview
Access: all menus
Throughout the measurement channel configuration, an overview of the most important
currently defined settings is provided in the "Overview".
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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):
1. Input and Frontend Settings
See Chapter 5.2, "Input, output and frontend settings", on page 44
2. Trigger
See Chapter 5.3, "Trigger settings", on page 57
3. Data Acquisition
See Chapter 5.4, "Data acquisition and detection", on page 62
4. Display Configuration
See Chapter 6.1, "Display configuration", on page 69
To configure settings
► Select any button to open the corresponding dialog box. To configure a particular
setting displayed in the "Overview", simply select the setting on the touch screen.
The corresponding dialog box is opened with the focus on the selected setting.
For step-by-step instructions on configuring VOR/ILS measurements, see Chapter 7,
"How to perform VOR/ILS measurements", on page 83.
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.
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Configuration
Input, output and frontend settings
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 96
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.
Select Measurement
Selects a measurement to be performed.
See "Selecting the measurement type" on page 28.
Remote command:
CALCulate<n>:AVIonics[:STANdard] on page 96
5.2 Input, output and frontend settings
Access: "Overview" ≥ "Input/Frontend"
The R&S FSW can evaluate signals from different input sources and provide various
types of output (such as noise or trigger signals).
The frequency and amplitude settings represent the "frontend" of the measurement
setup.
● Input source settings...............................................................................................44
● Frequency settings..................................................................................................49
● Amplitude settings...................................................................................................50
● Output settings........................................................................................................54
5.2.1 Input source settings
Access: "Overview" > "Input" > "Input Source"
Or: [INPUT/OUTPUT] > "Input Source Config"
The input source determines which data the R&S FSW will analyze.
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5.2.1.1 Radio frequency input
Configuration
Input, output and frontend settings
Further input sources
The R&S FSW Avionics (VOR/ILS) measurements application application can also
process input from the following sources:
●
I/Q Input files
●
Probes
Access: "Overview" > "Input/Frontend" > "Input Source" > "Radio Frequency"
Or: [INPUT/OUTPUT] > "Input Source Config" > "Input Source" > "Radio Frequency"
The only input source for the R&S FSW Avionics (VOR/ILS) measurements application
is "Radio Frequency", i.e. the signal at the [RF Input] connector of the R&S FSW.
Radio Frequency State
Input Coupling...............................................................................................................46
Impedance.................................................................................................................... 46
Direct Path.................................................................................................................... 46
High Pass Filter 1 to 3 GHz...........................................................................................47
YIG-Preselector.............................................................................................................47
Input Connector.............................................................................................................47
Radio Frequency State
Activates input from the "RF Input" connector.
For R&S FSW85 models with two input connectors, you must define which input
source is used for each measurement channel.
................................................................................................. 45
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Configuration
Input, output and frontend settings
If an external frontend is active, select the connector the external frontend is connected
to. You cannot use the other RF input connector simultaneously for the same channel.
However, you can configure the use of the other RF input connector for another active
channel at the same time.
"Input 1"
1.00 mm RF input connector for frequencies up to 85 GHz (90 GHz
with option R&S FSW-B90G)
"Input 2"
Remote command:
INPut<ip>:SELect on page 101
INPut<ip>:TYPE on page 101
Input Coupling
The RF input of the R&S FSW can be coupled by alternating current (AC) or direct current (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 98
Impedance
For Avionics measurements, the impedance is always 50 Ω and cannot be changed.
Remote command:
INPut<ip>:IMPedance on page 100
1.85 mm RF input connector for frequencies up to 67 GHz
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.
"Auto"
"Off"
(Default) The direct path is used automatically for frequencies close
to zero.
The analog mixer path is always used.
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Configuration
Input, output and frontend settings
Remote command:
INPut<ip>:DPATh on page 98
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 100
YIG-Preselector
Enables or disables the YIG-preselector, if available on the R&S FSW.
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 100
Input Connector
Determines which connector the input data for the measurement is taken from.
"RF"
"RF Probe"
Remote command:
INPut<ip>:CONNector on page 97
5.2.1.2 Settings for input from I/Q data files
Access: "Overview" > "Input/Frontend" > "Input Source" > "I/Q File"
Or: [INPUT/OUTPUT] > "Input Source Config" > "Input Source" > "I/Q File"
(Default:) The "RF Input" connector
The "RF Input" connector with an adapter for a modular probe
This setting is only available if a probe is connected to the "RF Input"
connector.
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Configuration
Input, output and frontend settings
I/Q Input File State........................................................................................................ 48
Select I/Q data file.........................................................................................................48
File Repetitions............................................................................................................. 49
I/Q Input File State
Enables input from the selected I/Q input file.
If enabled, the application performs measurements on the data from this file. Thus,
most measurement settings related to data acquisition (attenuation, center frequency,
measurement bandwidth, sample rate) cannot be changed. The measurement time
can only be decreased to perform measurements on an extract of the available data
only.
Note: Even when the file input is disabled, the input file remains selected and can be
enabled again quickly by changing the state.
Remote command:
INPut<ip>:SELect on page 101
Select I/Q data file
Opens a file selection dialog box to select an input file that contains I/Q data.
The I/Q data file must be in one of the following supported formats:
.iq.tar
●
.iqw
●
.csv
●
.mat
●
.wv
●
.aid
●
For details on formats, see the R&S FSW I/Q Analyzer and I/Q Input user manual.
Note: Only a single data stream or channel can be used as input, even if multiple
streams or channels are stored in the file.
Note: For some file formats that do not provide the sample rate and measurement time
or record length, you must define these parameters manually. Otherwise the traces are
not visible in the result displays.
The default storage location for I/Q data files is C:\R_S\INSTR\USER.
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5.2.2 Frequency settings
Configuration
Input, output and frontend settings
Remote command:
INPut<ip>:FILE:PATH on page 99
File Repetitions
Determines how often the data stream is repeatedly copied in the I/Q data memory to
create a longer record. If the available memory is not sufficient for the specified number of repetitions, the largest possible number of complete data streams is used.
Remote command:
TRACe:IQ:FILE:REPetition:COUNt on page 102
Access: "Overview" > "Input/Frontend" > "Frequency"
Or: [FREQ]
Center Frequency......................................................................................................... 49
Center Frequency Stepsize...........................................................................................49
Frequency Offset...........................................................................................................50
Center Frequency
Defines the center frequency of the signal in Hertz.
Remote command:
[SENSe:]FREQuency:CENTer on page 103
Center Frequency Stepsize
Defines the step size by which the center frequency is increased or decreased using
the arrow keys.
When you use the rotary knob the center frequency changes in steps of only 1/10 of
the span.
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Configuration
Input, output and frontend settings
The step size can be coupled to another value or it can be manually set to a fixed
value.
"= Center"
"Manual"
Remote command:
[SENSe:]FREQuency:CENTer:STEP on page 103
Frequency Offset
Shifts the displayed frequency range along the x-axis by the defined offset.
This parameter has no effect on the instrument's hardware, on the captured data, or on
data processing. It is simply a manipulation of the final results in which absolute frequency values are displayed. Thus, the x-axis of a spectrum display is shifted by a
constant offset if it shows absolute frequencies. However, if it shows frequencies relative to the signal's center frequency, it is not shifted.
A frequency offset can be used to correct the display of a signal that is slightly distorted
by the measurement setup, for example.
The allowed values range from -1 THz to 1 THz. The default setting is 0 Hz.
Remote command:
[SENSe:]FREQuency:OFFSet on page 104
Sets the step size to the value of the center frequency. The used
value is indicated in the "Value" field.
Defines a fixed step size for the center frequency. Enter the step size
in the "Value" field.
5.2.3 Amplitude settings
Access: "Overview" > "Input/Frontend" > "Amplitude"
Or: [AMPT] > "Amplitude Config"
Amplitude settings affect the signal power or error levels.
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Configuration
Input, output and frontend settings
Reference Level............................................................................................................51
└ Shifting the Display (Offset)............................................................................ 51
RF Attenuation.............................................................................................................. 52
└ Attenuation Mode / Value................................................................................52
Using Electronic Attenuation.........................................................................................52
Input Settings................................................................................................................ 53
└ Preamplifier.....................................................................................................53
└ Ext. PA Correction...........................................................................................53
Reference Level
Defines the expected maximum input signal level. Signal levels above this value are
possibly not measured correctly, which is indicated by the "IF Overload" status display.
The reference level can also be used to scale power diagrams; the reference level is
then used for the calculation of the maximum on the y-axis.
Since the hardware of the R&S FSW is adapted according to this value, it is recommended that you set the reference level close above the expected maximum signal
level. Thus you ensure an optimum measurement (no compression, good signal-tonoise ratio).
Remote command:
DISPlay[:WINDow<n>][:SUBWindow<w>]:TRACe<t>:Y[:SCALe]:RLEVel
on page 104
Shifting the Display (Offset) ← Reference Level
Defines an arithmetic level offset. This offset is added to the measured level. In some
result displays, the scaling of the y-axis is changed accordingly.
Define an offset if the signal is attenuated or amplified before it is fed into the
R&S FSW so the application shows correct power results. All displayed power level
results are shifted by this value.
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Configuration
Input, output and frontend settings
The setting range is ±200 dB in 0.01 dB steps.
Note, however, that the internal reference level (used to adjust the hardware settings to
the expected signal) ignores any "Reference Level Offset". Thus, it is important to keep
in mind the actual power level the R&S FSW must handle. Do not rely on the displayed
reference level (internal reference level = displayed reference level - offset).
Remote command:
DISPlay[:WINDow<n>][:SUBWindow<w>]:TRACe<t>:Y[:SCALe]:RLEVel:
OFFSet on page 105
RF Attenuation
Defines the mechanical attenuation for RF input.
Attenuation Mode / Value ← RF Attenuation
The RF attenuation can be set automatically as a function of the selected reference
level (Auto mode). Automatic attenuation ensures that no overload occurs at the RF
Input connector for the current reference level. It is the default setting.
By default and when no (optional) electronic attenuation is available, mechanical
attenuation is applied.
In "Manual" mode, you can set the RF attenuation in 1 dB steps (down to 0 dB). Other
entries are rounded to the next integer value. The range is specified in the data sheet.
If the defined reference level cannot be set for the defined RF attenuation, the reference level is adjusted accordingly and the warning "limit reached" is displayed.
NOTICE! Risk of hardware damage due to high power levels. When decreasing the
attenuation manually, ensure that the power level does not exceed the maximum level
allowed at the RF input, as an overload can lead to hardware damage.
Remote command:
INPut<ip>:ATTenuation on page 107
INPut<ip>:ATTenuation:AUTO on page 108
Using Electronic Attenuation
If the (optional) Electronic Attenuation hardware is installed on the R&S FSW, you can
also activate an electronic attenuator.
In "Auto" mode, the settings are defined automatically; in "Manual" mode, you can
define the mechanical and electronic attenuation separately.
Note: Electronic attenuation is not available for stop frequencies (or center frequencies
in zero span) above 15 GHz.
In "Auto" mode, RF attenuation is provided by the electronic attenuator as much as
possible to reduce the amount of mechanical switching required. Mechanical attenuation can provide a better signal-to-noise ratio, however.
When you switch off electronic attenuation, the RF attenuation is automatically set to
the same mode (auto/manual) as the electronic attenuation was set to. Thus, the RF
attenuation can be set to automatic mode, and the full attenuation is provided by the
mechanical attenuator, if possible.
The electronic attenuation can be varied in 1 dB steps. If the electronic attenuation is
on, the mechanical attenuation can be varied in 5 dB steps. Other entries are rounded
to the next lower integer value.
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Configuration
Input, output and frontend settings
For the R&S FSW85, the mechanical attenuation can be varied only in 10 dB steps.
If the defined reference level cannot be set for the given attenuation, the reference
level is adjusted accordingly and the warning "limit reached" is displayed in the status
bar.
Remote command:
INPut<ip>:EATT:STATe on page 109
INPut<ip>:EATT:AUTO on page 108
INPut<ip>:EATT on page 108
Input Settings
Some input settings affect the measured amplitude of the signal, as well.
For information on other input settings, see Chapter 5.2.1.1, "Radio frequency input",
on page 45.
Preamplifier ← Input Settings
If the (optional) internal preamplifier hardware is installed, a preamplifier can be activated for the RF input signal.
You can use a preamplifier to analyze signals from DUTs with low output power.
Note: If an optional external preamplifier is activated, the internal preamplifier is auto-
matically disabled, and vice versa.
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 106
INPut<ip>:GAIN[:VALue] on page 107
Ext. PA Correction ← Input Settings
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.
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5.2.4 Output settings
Configuration
Input, output and frontend settings
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 105
Access: "Overview" > "Input/Frontend" > "Output"
The R&S FSW can provide output to special connectors for other devices.
For details on connectors refer to the R&S FSW Getting Started manual, "Front / Rear
Panel View" chapters.
How to provide trigger signals as output is described in detail in the R&S FSW User
Manual.
Noise Source Control....................................................................................................55
Trigger 2/3.....................................................................................................................55
└ Output Type.................................................................................................... 56
└ Level..................................................................................................... 56
└ Pulse Length.........................................................................................56
└ Send Trigger.........................................................................................56
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Configuration
Input, output and frontend settings
Noise Source Control
Enables or disables the 28 V voltage supply for an external noise source connected to
the "Noise source control / Power sensor") connector. By switching the supply voltage
for an external noise source on or off in the firmware, you can enable or disable the
device as required.
External noise sources are useful when you are measuring power levels that fall below
the noise floor of the R&S FSW itself, for example when measuring the noise level of
an amplifier.
In this case, you can first connect an external noise source (whose noise power level is
known in advance) to the R&S FSW and measure the total noise power. From this
value, you can determine the noise power of the R&S FSW. Then when you measure
the power level of the actual DUT, you can deduct the known noise level from the total
power to obtain the power level of the DUT.
Remote command:
DIAGnostic:SERVice:NSOurce on page 102
Trigger 2/3
The trigger input and output functionality depends on how the variable "Trigger Input/
Output" connectors are used.
"Trigger 1"
"Trigger 2"
"Trigger 3"
"Input"
"Trigger 1" is input only.
Defines the usage of the variable "Trigger Input/Output" connector on
the front panel
(not available for R&S FSW85 models with 2 RF input connectors)
Defines the usage of the variable "Trigger 3 Input/Output" connector
on the rear panel
The signal at the connector is used as an external trigger source by
the R&S FSW. Trigger input parameters are available in the "Trigger"
dialog box.
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Configuration
Input, output and frontend settings
"Output"
Remote command:
OUTPut<up>:TRIGger<tp>:DIRection on page 114
Output Type ← Trigger 2/3
Type of signal to be sent to the output
"Device Trig-
gered"
"Trigger
Armed"
"User Defined"
Remote command:
OUTPut<up>:TRIGger<tp>:OTYPe on page 115
Level ← Output Type ← Trigger 2/3
Defines whether a high (1) or low (0) constant signal is sent to the trigger output connector (for "Output Type": "User Defined".
The trigger pulse level is always opposite to the constant signal level defined here. For
example, for "Level" = "High", a constant high signal is output to the connector until you
select the Send Trigger function. Then, a low pulse is provided.
The R&S FSW sends a trigger signal to the output connector to be
used by connected devices.
Further trigger parameters are available for the connector.
(Default) Sends a trigger when the R&S FSW triggers.
Sends a (high level) trigger when the R&S FSW is in "Ready for trigger" state.
This state is indicated by a status bit in the STATus:OPERation register (bit 5), as well as by a low-level signal at the "AUX" port (pin 9).
Sends a trigger when you select the "Send Trigger" button.
In this case, further parameters are available for the output signal.
Remote command:
OUTPut<up>:TRIGger<tp>:LEVel on page 114
Pulse Length ← Output Type ← Trigger 2/3
Defines the duration of the pulse (pulse width) sent as a trigger to the output connector.
Remote command:
OUTPut<up>:TRIGger<tp>:PULSe:LENGth on page 116
Send Trigger ← Output Type ← Trigger 2/3
Sends a user-defined trigger to the output connector immediately.
Note that the trigger pulse level is always opposite to the constant signal level defined
by the output Level setting. For example, for "Level" = "High", a constant high signal is
output to the connector until you select the "Send Trigger" function. Then, a low pulse
is sent.
Which pulse level is sent is indicated by a graphic on the button.
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5.3 Trigger settings
Configuration
Trigger settings
Remote command:
OUTPut<up>:TRIGger<tp>:PULSe:IMMediate on page 115
Access: "Overview" > "Signal Capture" > "Trigger Source"
Trigger settings determine when the input signal is measured.
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.
For step-by-step instructions on configuring triggered measurements, see the main
R&S FSW User Manual.
Trigger Source...............................................................................................................58
└ Trigger Source................................................................................................ 58
└ Free Run...............................................................................................58
└ External Trigger 1/2/3........................................................................... 58
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Configuration
Trigger settings
└ IF Power............................................................................................... 59
└ RF Power..............................................................................................59
└ I/Q Power..............................................................................................59
└ Trigger Level...................................................................................................59
└ Drop-Out Time................................................................................................ 60
└ Trigger Offset..................................................................................................60
└ Hysteresis....................................................................................................... 60
└ Trigger Holdoff................................................................................................ 60
└ Slope...............................................................................................................60
Trigger 2/3.....................................................................................................................61
└ Output Type.................................................................................................... 61
└ Level..................................................................................................... 62
└ Pulse Length.........................................................................................62
└ Send Trigger.........................................................................................62
Trigger Source
The trigger settings define the beginning of a measurement.
Trigger Source ← Trigger Source
Defines 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 113
Free Run ← Trigger Source ← 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 113
External Trigger 1/2/3 ← Trigger Source ← 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 59).
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.
For R&S FSW85 models, "Trigger 2" is not available due to the second RF input connector on the front panel.
"External Trigger 3"
Trigger signal from the "TRIGGER 3 INPUT / OUTPUT" connector on
the rear panel.
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Configuration
Trigger settings
Remote command:
TRIG:SOUR EXT, TRIG:SOUR EXT2
TRIG:SOUR EXT3
See TRIGger[:SEQuence]:SOURce on page 113
IF Power ← Trigger Source ← Trigger Source
The R&S FSW starts capturing data as soon as the trigger level is exceeded around
the third intermediate frequency.
For frequency sweeps, the third IF represents the start frequency. The trigger threshold
depends on the defined trigger level, as well as on the RF attenuation and preamplification. A reference level offset, if defined, is also considered. The trigger bandwidth at
the intermediate frequency depends on the RBW and sweep type. For details on available trigger levels and trigger bandwidths, see the instrument data sheet.
For measurements on a fixed frequency (e.g. zero span or I/Q measurements), the
third IF represents the center frequency.
This trigger source is only available for RF input.
The available trigger levels depend on the RF attenuation and preamplification. A refer-
ence level offset, if defined, is also considered.
For details on available trigger levels and trigger bandwidths, see the data sheet.
Remote command:
TRIG:SOUR IFP, see TRIGger[:SEQuence]:SOURce on page 113
RF Power ← Trigger Source ← Trigger Source
Defines triggering of the measurement via signals which are outside the displayed
measurement range.
For this purpose, the instrument uses a level detector at the first intermediate frequency.
The resulting trigger level at the RF input depends on the RF attenuation and preamplification. For details on available trigger levels, see the instrument's data sheet.
Note: If the input signal contains frequencies outside of this range (e.g. for fullspan
measurements), the measurement can be aborted. A message indicating the allowed
input frequencies is displayed in the status bar.
A "Trigger Offset", "Trigger Polarity" and "Trigger Holdoff" (to improve the trigger stability) can be defined for the RF trigger, but no "Hysteresis".
Remote command:
TRIG:SOUR RFP, see TRIGger[:SEQuence]:SOURce on page 113
I/Q Power ← Trigger Source ← Trigger Source
Triggers the measurement when the magnitude of the sampled I/Q data exceeds the
trigger threshold.
Remote command:
TRIG:SOUR IQP, see TRIGger[:SEQuence]:SOURce on page 113
Trigger Level ← Trigger Source
Defines the trigger level for the specified trigger source.
For details on supported trigger levels, see the instrument data sheet.
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Configuration
Trigger settings
Remote command:
TRIGger[:SEQuence]:LEVel:IFPower on page 111
TRIGger[:SEQuence]:LEVel:IQPower on page 112
TRIGger[:SEQuence]:LEVel[:EXTernal<port>] on page 111
Drop-Out Time ← Trigger Source
Defines the time that the input signal must stay below the trigger level before triggering
again.
Remote command:
TRIGger[:SEQuence]:DTIMe on page 110
Trigger Offset ← Trigger Source
Defines the time offset between the trigger event and the start of the measurement.
Offset > 0: Start of the measurement is delayed
Offset < 0: Measurement starts earlier (pretrigger)
Remote command:
TRIGger[:SEQuence]:HOLDoff[:TIME] on page 110
Hysteresis ← Trigger Source
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 111
Trigger Holdoff ← Trigger Source
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 110
Slope ← Trigger Source
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 113
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Configuration
Trigger settings
Trigger 2/3
The trigger input and output functionality depends on how the variable "Trigger Input/
Output" connectors are used.
"Trigger 1"
"Trigger 2"
"Trigger 1" is input only.
Defines the usage of the variable "Trigger Input/Output" connector on
the front panel
(not available for R&S FSW85 models with 2 RF input connectors)
"Trigger 3"
"Input"
"Output"
Remote command:
OUTPut<up>:TRIGger<tp>:DIRection on page 114
Output Type ← Trigger 2/3
Type of signal to be sent to the output
"Device Trig-
gered"
"Trigger
Armed"
"User Defined"
Remote command:
OUTPut<up>:TRIGger<tp>:OTYPe on page 115
Defines the usage of the variable "Trigger 3 Input/Output" connector
on the rear panel
The signal at the connector is used as an external trigger source by
the R&S FSW. Trigger input parameters are available in the "Trigger"
dialog box.
The R&S FSW sends a trigger signal to the output connector to be
used by connected devices.
Further trigger parameters are available for the connector.
(Default) Sends a trigger when the R&S FSW triggers.
Sends a (high level) trigger when the R&S FSW is in "Ready for trigger" state.
This state is indicated by a status bit in the STATus:OPERation register (bit 5), as well as by a low-level signal at the "AUX" port (pin 9).
Sends a trigger when you select the "Send Trigger" button.
In this case, further parameters are available for the output signal.
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Configuration
Data acquisition and detection
Level ← Output Type ← Trigger 2/3
Defines whether a high (1) or low (0) constant signal is sent to the trigger output connector (for "Output Type": "User Defined".
The trigger pulse level is always opposite to the constant signal level defined here. For
example, for "Level" = "High", a constant high signal is output to the connector until you
select the Send Trigger function. Then, a low pulse is provided.
Remote command:
OUTPut<up>:TRIGger<tp>:LEVel on page 114
Pulse Length ← Output Type ← Trigger 2/3
Defines the duration of the pulse (pulse width) sent as a trigger to the output connector.
Remote command:
OUTPut<up>:TRIGger<tp>:PULSe:LENGth on page 116
Send Trigger ← Output Type ← Trigger 2/3
Sends a user-defined trigger to the output connector immediately.
Note that the trigger pulse level is always opposite to the constant signal level defined
by the output Level setting. For example, for "Level" = "High", a constant high signal is
output to the connector until you select the "Send Trigger" function. Then, a low pulse
is sent.
Which pulse level is sent is indicated by a graphic on the button.
Remote command:
OUTPut<up>:TRIGger<tp>:PULSe:IMMediate on page 115
5.4 Data acquisition and detection
Access: "Overview" > "Data Acquisition"
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Configuration
Data acquisition and detection
Demodulation Bandwidth.............................................................................................. 63
Measurement Time....................................................................................................... 63
RBW..............................................................................................................................64
Demodulation Bandwidth
The R&S FSW Avionics (VOR/ILS) measurements application captures I/Q data using
digital filters with quasi-rectangular amplitude responses. The demodulation bandwidth
defines the width of the filter's flat passband.
For more information, see Chapter 3.3.1, "Demodulation bandwidth", on page 25.
Depending on the selected DBW mode, the value is either determined automatically or
can be defined manually.
"Auto mode"
(Default) The DBW is determined automatically by the R&S FSW
Avionics (VOR/ILS) measurements application.
For ILS measurements: 12.5 kHz
For VOR measurements: 25 kHz
"Manual mode"
Remote command:
[SENSe:]ADEMod:BWIDth:DEModulation on page 116
[SENSe:]ADEMod:BWIDth:DEModulation:AUTO on page 117
Measurement Time
Defines the net, settled measurement length; internally, the R&S FSW Avionics (VOR/
ILS) measurements application captures data slightly longer to allow for all filters to
settle.
"Auto"
"Manual"
The user-defined DBW is used. For a list of available demodulation
bandwidths, see Available demodulation bandwidths and measure-
ment times for ILS measurements and Table 3-2.
(Default:) The required time (1 s) is determined by the R&S FSW
Avionics (VOR/ILS) measurements application. The currently used
measurement time is indicated for reference only
The measurement time is defined manually; enter the measurement
time in seconds
For a list of available measurement times depending on the Demodu-
lation Bandwidth, see Table 3-1 and Table 3-2.
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Configuration
Sweep settings
Remote command:
[SENSe:]SWEep:TIME on page 118
[SENSe:]SWEep:TIME:AUTO on page 119
RBW
Defines the resolution bandwidth for Modulation Spectrum results. The available RBW
values depend on the Demodulation Bandwidth and the Measurement Time.
Depending on the selected RBW mode, the value is either determined automatically or
can be defined manually. As soon as you enter a value in the input field, the RBW
mode is changed to "Manual".
"Auto mode"
"Manual mode"
Remote command:
[SENSe:]ADEMod:SPECtrum:BWIDth[:RESolution] on page 117
[SENSe:]ADEMod:SPECtrum:BWIDth[:RESolution]:AUTO on page 118
(Default) The RBW is determined automatically depending on the
Demodulation Bandwidth and the Measurement Time.
The user-defined RBW is used.
5.5 Sweep settings
Access: [SWEEP]
The sweep settings define how often data from the input signal is acquired and then
evaluated.
Continuous Sweep / Run Cont......................................................................................64
Single Sweep / Run Single............................................................................................65
Measurement Time....................................................................................................... 65
Continuous Sweep / Run Cont
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 122
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Configuration
Demodulation spectrum
Single Sweep / Run Single
After triggering, starts the number of sweeps set in "Sweep Count". The measurement
stops after the defined number of sweeps has been performed.
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.
Remote command:
INITiate<n>[:IMMediate] on page 123
Measurement Time
Defines the net, settled measurement length; internally, the R&S FSW Avionics (VOR/
ILS) measurements application captures data slightly longer to allow for all filters to
settle.
"Auto"
"Manual"
Remote command:
[SENSe:]SWEep:TIME on page 118
[SENSe:]SWEep:TIME:AUTO on page 119
(Default:) The required time (1 s) is determined by the R&S FSW
Avionics (VOR/ILS) measurements application. The currently used
measurement time is indicated for reference only
The measurement time is defined manually; enter the measurement
time in seconds
For a list of available measurement times depending on the Demodu-
lation Bandwidth, see Table 3-1 and Table 3-2.
5.6 Demodulation spectrum
Access: [MEAS CONFIG] > "Spectrum"
The demodulation spectrum defines which span of the demodulated data is evaluated.
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Configuration
Demodulation spectrum
AF Span........................................................................................................................ 66
└ AF Center........................................................................................................66
└ AF Start...........................................................................................................66
└ AF Stop...........................................................................................................66
└ AF Span..........................................................................................................67
└ AF Full Span................................................................................................... 67
Distortion.......................................................................................................................67
└ Deviation Trace...............................................................................................67
└ Harmonic Frequency.......................................................................................67
└ Distortion Max Frequency...............................................................................67
└ Fundamental Frequency.................................................................................68
AF Span
Defines the frequency range to be demodulated in the Modulation Spectrum.
AF Center ← AF Span
Defines the center frequency of the demodulated data to evaluate in the Modulation
Spectrum.
Remote command:
[SENSe:]ADEMod:AF:CENTer on page 120
AF Start ← AF Span
Defines the start frequency of the demodulated data to evaluate in the Modulation
Spectrum.
Remote command:
[SENSe:]ADEMod:AF:STARt on page 120
AF Stop ← AF Span
Defines the stop frequency of the demodulated data to evaluate in the Modulation
Spectrum display.
The maximum AF stop frequency corresponds to half the demodulation bandwidth.
Remote command:
[SENSe:]ADEMod:AF:STOP on page 121
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Configuration
Demodulation spectrum
AF Span ← AF Span
Defines the span (around the center frequency) of the demodulated data to evaluate in
the Modulation Spectrum. The maximum span is DBW/2.
Remote command:
[SENSe:]ADEMod:AF:SPAN on page 120
[SENSe:]ADEMod:AF:SPAN:FULL on page 120
AF Full Span ← AF Span
Sets the span (around the center frequency) of the demodulated data to the maximum
of DBW/2.
Remote command:
[SENSe:]ADEMod:AF:SPAN:FULL on page 120
Distortion
Configures the optional harmonic distortion measurement.
Deviation Trace ← Distortion
Switches the scaling mode for the deviation trace in the Modulation Spectrum between
linear and logarithmic.
Note: this setting only affects the graphical results, not the numerical results.
"Linear"
"Logarithmic"
Scaling in percent
(Default:) Scaling in dB
Remote command:
DISPlay[:WINDow<n>]:TRACe<t>:Y:SPACing on page 119
Harmonic Frequency ← Distortion
Defines the frequency at which the harmonic distortion is measured.
Tip: the fixed "H1" marker in the Modulation Spectrum display indicates the distortion
at the given frequency relative to the modulation at the set Fundamental Frequency.
Remote command:
CALCulate<n>:AVIonics:SHD:FREQuency on page 152
Distortion Max Frequency ← Distortion
Defines the upper frequency limit for most total harmonic distortion measurements.
Only harmonics frequencies not exceeding this value are included in the THD calculation. The maximum allowed value is half the defined Demodulation Bandwidth.
The setting has no effect on K2 and K3 or FM distortion results.
The following table shows the maximum frequencies included in the THD calculations
for different signal components.
Table 5-1: Maximum frequencies included in the THD calculations
Signal component Maximum frequency included in THD
ILS
90 Hz AM "Distortion Max Frequency"
150 Hz AM "Distortion Max Frequency"
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Configuration
Demodulation spectrum
Signal component Maximum frequency included in THD
90/150 Hz AM "Distortion Max Frequency"
Voice / Ident 0.5 * Demodulation Bandwidth
VOR
30 Hz AM "Distortion Max Frequency"
9.96 kHz AM 0.5 * Demodulation Bandwidth
30 Hz FM min ("Distortion Max Frequency", 5*30 Hz)
Voice / Ident 8.16 kHz
Remote command:
CALCulate<n>:AVIonics:THD:FREQuency:UPPer on page 154
Fundamental Frequency ← Distortion
Defines the reference for the harmonic distortion measurement; the modulation depth
measured at the Harmonic Frequency is set in relation to the modulation depth of the
selected fundamental frequency.
Table 5-2: Used reference values depending on selected frequency
Setting Reference value Remote command
ILS
"90 Hz" Modulation depth at nominal 90 Hz
"150 Hz" Modulation depth at nominal 150 Hz
"90 Hz &
150 Hz"
"Identification"
VOR
"30 Hz" Modulation depth at nominal 30 Hz
"9.96 kHz" Modulation depth at nominal 9960 Hz (inte-
"Identification"
Average of the modulation depth values at
nominal 90 Hz and nominal 150 Hz
Modulation depth at the currently estimated
identification frequency
gration in specific bandwidth, see "THD"
on page 39)
Modulation depth at the currently estimated
identification frequency
CALC:AVI:THD:FREQ:FUND '90'
CALC:AVI:THD:FREQ:FUND '150'
CALC:AVI:THD:FREQ:FUND '90_150'
CALC:AVI:THD:FREQ:FUND 'ID'
CALC:AVI:THD:FREQ:FUND '30'
CALC:AVI:THD:FREQ:FUND '9960'
CALC:AVI:THD:FREQ:FUND 'ID'
Remote command:
CALCulate<n>:AVIonics:THD:FREQuency:FUNDament on page 154
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6 Analysis
6.1 Display configuration
Analysis
Result configuration
General result settings concerning the trace, markers, diagrams etc. can be configured
in the R&S FSW Avionics (VOR/ILS) measurements application.
● Display configuration...............................................................................................69
● Result configuration................................................................................................ 69
● Markers................................................................................................................... 72
● Export functions...................................................................................................... 80
Access: "Overview" > "Display Config"
The captured signal can be displayed using various evaluation methods. All evaluation
methods available for the R&S FSW Avionics (VOR/ILS) measurements application
are displayed in the evaluation bar in SmartGrid mode.
Drag one or more evaluations to the display area and configure the layout as required.
To close the SmartGrid mode and restore the previous softkey menu select the
"Close" icon in the righthand corner of the toolbar, or press any key.
Up to 16 evaluation methods can be displayed simultaneously in separate windows.
The VOR/ILS evaluation methods are described in Chapter 4, "Measurements and
result displays", on page 28.
For details on working with the SmartGrid, see the R&S FSW Getting Started manual.
6.2 Result configuration
Access: [MEAS CONFIG] > "Result Config"
Some evaluation methods require or allow for additional settings to configure the result
display. Note that the available settings depend on the selected window (see "Specific
Settings for" on page 44).
6.2.1 Y-Scaling
Access: [MEAS CONFIG] > "Result Config" > "Y Scaling" tab
The scaling for the vertical axis is highly configurable, using either absolute or relative
values.
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Analysis
Result configuration
Auto Scale Once........................................................................................................... 70
Absolute Scaling (Min/Max Values)...............................................................................70
Relative Scaling (RefeFSWA_K95_UserManual+Help, 9, en_USrence/ per Division)
...................................................................................................................................... 70
└ Per Division.....................................................................................................71
└ Ref Position.....................................................................................................71
└ Ref Value........................................................................................................ 71
Auto Scale Once
Automatically determines the optimal range and reference level position to be displayed for the current measurement settings.
The display is only set once; it is not adapted further if the measurement settings are
changed again.
Remote command:
DISPlay[:WINDow<n>][:SUBWindow<w>]:TRACe<t>:Y[:SCALe]:AUTO ONCE
on page 131
Absolute Scaling (Min/Max Values)
Define the scaling using absolute minimum and maximum values.
Remote command:
DISPlay[:WINDow<n>]:TRACe<t>:Y[:SCALe]:MAXimum on page 132
DISPlay[:WINDow<n>]:TRACe<t>:Y[:SCALe]:MINimum on page 133
Relative Scaling (RefeFSWA_K95_UserManual+Help, 9, en_USrence/ per Division)
Defines the scaling relative to a reference value, with a specified value range per division.
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Analysis
Result configuration
Per Division ← Relative Scaling (RefeFSWA_K95_UserManual+Help, 9,
en_USrence/ per Division)
Defines the value range to be displayed per division of the diagram (1/10 of total
range).
Note: The value defined per division refers to the default display of ten divisions on the
y-axis. If the window is reduced in height, for example, not all divisions are displayed.
In this case, the range per division is increased to display the same result range in the
smaller window. In this case, the per division value does not correspond to the actual
display.
Remote command:
DISPlay[:WINDow<n>][:SUBWindow<w>]:TRACe<t>:Y[:SCALe]:PDIVision
on page 132
Ref Position ← Relative Scaling (RefeFSWA_K95_UserManual+Help, 9,
en_USrence/ per Division)
Defines the position of the reference value in percent of the total y-axis range.
Remote command:
DISPlay[:WINDow<n>][:SUBWindow<w>]:TRACe<t>:Y[:SCALe]:RPOSition
on page 132
Ref Value ← Relative Scaling (RefeFSWA_K95_UserManual+Help, 9, en_USrence/
per Division)
Defines the reference value to be displayed at the specified reference position.
Remote command:
DISPlay[:WINDow<n>]:TRACe<t>:Y[:SCALe]:RVALue on page 133
6.2.2 Units
Some parameters can be provided in different units.
Distortion.......................................................................................................................71
ILS DDM........................................................................................................................71
Deviation Trace.............................................................................................................72
VOR Phase................................................................................................................... 72
Distortion
Switches units between dB and percent for the total harmonic distortion (THD), K2 and
K3 results in the Distortion Summary and Result Summary and the corresponding
remote commands.
Remote command:
UNIT<n>:THD on page 134
ILS DDM
Determines the unit for ILS DDM results (relevant for ILS measurements only, see also
"ILS DDM" on page 36).
"unitless"
"percent"
Absolute results
Relative results
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Analysis
Markers
Remote command:
UNIT<n>:DDM on page 133
Deviation Trace
Switches the scaling mode for the deviation trace in the Modulation Spectrum between
linear and logarithmic.
Note: this setting only affects the graphical results, not the numerical results.
"Linear"
"Logarithmic"
Remote command:
DISPlay[:WINDow<n>]:TRACe<t>:Y:SPACing on page 119
VOR Phase
Only relevant for VOR measurements: Switches between a phase display in from or to
notation.
For details, see Chapter 3.3.3, "Phase notation in VOR measurements", on page 27.
Remote command:
UNIT<n>:VORDirection on page 134
Scaling in percent
(Default:) Scaling in dB
6.3 Markers
Access: [MKR]
Markers help you analyze your measurement results by determining particular values
in the diagram. Thus you can extract numeric values from a graphical display.
Fixed markers (H1, F1, F2)
Two fixed markers (H1, F1) are always active and displayed in the Modulation Spec-
trum result display and the marker table. F1 indicates the currently selected Fundamental Frequency for distortion measurement, as well as the measured power level. A
third marker, F2, is set to a second fundamental frequency for ILS measurements on
the 90 Hz + 150 Hz components only. H1 indicates the currently selected frequency for
distortion measurement (see Harmonic Frequency) and the power measured at that
frequency.
The distortion at this frequency (measured as the power in relation to the power at the
fundamental frequency) is indicated as an additional marker result ("Dist") in the Modu-
lation Spectrum.
As opposed to common markers, H1, F1 and F2 markers cannot be repositioned manually, for example by dragging them on the screen. Their position is automatically
defined by the Harmonic Frequency and Fundamental Frequency settings, respectively
(see "Distortion" on page 67). These markers cannot be deactivated or configured.
Due to these special markers, only 13 regular markers are configurable in the R&S
FSW Avionics (VOR/ILS) measurements application.
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6.3.1 Individual marker settings
Analysis
Markers
● Individual marker settings....................................................................................... 73
● General marker settings..........................................................................................77
● Marker search settings............................................................................................78
● Marker positioning functions................................................................................... 79
Up to 14 markers or delta markers can be activated for each window simultaneously.
Initial marker setup is performed using the "Marker" dialog box.
The markers are distributed among three tabs for a better overview. By default, the first
marker is defined as a normal marker, whereas all others are defined as delta markers
with reference to the first marker. All markers are assigned to trace 1, but only the first
marker is active.
Marker 1 / Marker 2 / Marker 3 / Marker 4.................................................................... 74
Selected Marker............................................................................................................74
Marker State..................................................................................................................74
Marker Position X-value................................................................................................74
Marker Type..................................................................................................................74
Reference Marker......................................................................................................... 75
Linking to Another Marker.............................................................................................75
Assigning the Marker to a Trace................................................................................... 75
Select Marker................................................................................................................75
All Markers Off...............................................................................................................76
Fixed markers (H1, F1, F2)...........................................................................................76
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Analysis
Markers
Marker 1 / Marker 2 / Marker 3 / Marker 4
The "Marker X" softkey activates the corresponding marker and opens an edit dialog
box to enter the marker position ("X-value"). Pressing the softkey again deactivates the
selected marker.
Marker 1 is always the default reference marker for relative measurements. If activated, markers 2 to 4 are delta markers that refer to marker 1. These markers can be
converted into markers with absolute value display using the "Marker Type" function.
If normal marker 1 is the active marker, pressing the "Mkr Type" softkey switches on an
additional delta marker 1.
Remote command:
CALCulate<n>:MARKer<m>[:STATe] on page 138
CALCulate<n>:MARKer<m>:X on page 139
CALCulate<n>:MARKer<m>:Y? on page 146
CALCulate<n>:DELTamarker<m>[:STATe] on page 136
CALCulate<n>:DELTamarker<m>:X on page 137
CALCulate<n>:DELTamarker<m>:X:RELative? on page 145
CALCulate<n>:DELTamarker<m>:Y? on page 146
Selected Marker
Marker name. The marker which is currently selected for editing is highlighted orange.
Remote command:
Marker selected via suffix <m> in remote commands.
Marker State
Activates or deactivates the marker in the diagram.
Remote command:
CALCulate<n>:MARKer<m>[:STATe] on page 138
CALCulate<n>:DELTamarker<m>[:STATe] on page 136
Marker Position X-value
Defines the position (x-value) of the marker in the diagram. For normal markers, the
absolute position is indicated. For delta markers, the position relative to the reference
marker is provided.
To create a delta marker in a fixed distance to another marker, define the distance as
the x-value for the delta marker. Then link the delta marker to another marker using the
Linking to Another Marker function.
Remote command:
CALCulate<n>:MARKer<m>:X on page 139
CALCulate<n>:DELTamarker<m>:X on page 137
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.
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Analysis
Markers
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 138
CALCulate<n>:DELTamarker<m>[:STATe] on page 136
Reference Marker
Defines a marker as the reference marker which is used to determine relative analysis
results (delta marker values).
Remote command:
CALCulate<n>:DELTamarker<m>:MREFerence on page 135
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).
Linking to Another Marker
Links the current marker to the marker selected from the list of active markers. If the xaxis value of the initial marker is changed, the linked marker follows to the same position on the x-axis. Linking is off by default.
Using this function you can set two markers on different traces to measure the difference (e.g. between a max hold trace and a min hold trace or between a measurement
and a reference trace).
For linked delta markers, the x-value of the delta marker is 0 Hz by default. To create a
delta marker in a fixed distance to another marker, define the distance as the x-value
for the linked delta marker.
Remote command:
CALCulate<n>:MARKer<ms>:LINK:TO:MARKer<md> on page 138
CALCulate<n>:DELTamarker<ms>:LINK:TO:MARKer<md> on page 137
CALCulate<n>:DELTamarker<m>:LINK on page 135
Assigning the Marker to a Trace
The "Trace" setting assigns the selected marker to an active trace. The trace determines which value the marker shows at the marker position. If the marker was previously assigned to a different trace, the marker remains on the previous frequency or
time, but indicates the value of the new trace.
If a trace is turned off, the assigned markers and marker functions are also deactivated.
Remote command:
CALCulate<n>:MARKer<m>:TRACe on page 139
Select Marker
The "Select Marker" function opens a dialog box to select and activate or deactivate
one or more markers quickly.
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Markers
Remote command:
CALCulate<n>:MARKer<m>[:STATe] on page 138
CALCulate<n>:DELTamarker<m>[:STATe] on page 136
All Markers Off
Deactivates all markers in one step.
Remote command:
CALCulate<n>:MARKer<m>:AOFF on page 137
Fixed markers (H1, F1, F2)
Two fixed markers (H1, F1) are always active and displayed in the Modulation Spec-
trum result display and the "Marker Table". F1 indicates the currently selected Funda-
mental Frequency for distortion measurement, as well as the measured power level. A
third marker, F2, is set to a second fundamental frequency for ILS measurements on
the 90 Hz + 150 Hz components only. H1 indicates the currently selected frequency for
distortion measurement (see Harmonic Frequency) and the power measured at that
frequency.
The distortion at this frequency (measured as the power in relation to the power at the
fundamental frequency) is indicated as an additional marker result ("Dist") in the Modu-
lation Spectrum.
As opposed to common markers, H1, F1 and F2 markers cannot be repositioned manually, for example by dragging them on the screen. Their position is automatically
defined by the Harmonic Frequency and Fundamental Frequency settings, respectively
(see "Distortion" on page 67). These markers cannot be deactivated or configured.
Remote command:
CALCulate<n>:AVIonics:SHD:RESult? on page 153
CALCulate<n>:AVIonics:SHD:FREQuency on page 152
CALCulate<n>:AVIonics:THD:FREQuency:FUNDament on page 154
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6.3.2 General marker settings
Analysis
Markers
Access: "Overview" > "Analysis" > "Marker" > "Marker Settings"
Or: [MKR] > "Marker Config" > "Marker Settings" tab
Marker Table Display
Defines how the marker information is displayed.
"On"
"Off"
"Auto"
Remote command:
DISPlay[:WINDow<n>]:MTABle on page 140
Marker Info
Turns the marker information displayed in the diagram on and off.
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.
(Default) If more than two markers are active, the marker table is displayed automatically.
If Marker Info is active, the marker information for up to two markers
is displayed in the diagram area.
Remote command:
DISPlay[:WINDow<n>]:MINFo[:STATe] on page 140
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6.3.3 Marker search settings
Analysis
Markers
Access: "Overview" > "Analysis" > "Marker" > "Search"
Access: [MKR ->] > "Search Config"
Several functions are available to set the marker to a specific position very quickly and
easily. In order to determine the required marker position, searches can be performed.
The search results can be influenced by special settings.
Search Mode for Next Peak..........................................................................................78
Peak Excursion............................................................................................................. 78
Search Mode for Next Peak
Selects the search mode for the next peak search.
"Left"
"Absolute"
"Right"
Remote command:
Chapter 9.6.3.3, "Positioning the marker", on page 141
Peak Excursion
Defines the minimum level value by which a signal must rise or fall so that it is identified as a maximum or a minimum by the search functions.
Remote command:
CALCulate<n>:MARKer<m>:PEXCursion on page 140
Determines the next maximum/minimum to the left of the current
peak.
Determines the next maximum/minimum to either side of the current
peak.
Determines the next maximum/minimum to the right of the current
peak.
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6.3.4 Marker positioning functions
Analysis
Markers
Access: [MKR ->]
The following functions set the currently selected marker to the result of a peak search.
Peak Search..................................................................................................................79
Search Next Peak......................................................................................................... 79
Search Minimum........................................................................................................... 79
Search Next Minimum...................................................................................................79
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 142
CALCulate<n>:DELTamarker<m>:MAXimum[:PEAK] on page 144
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 141
CALCulate<n>:MARKer<m>:MAXimum:RIGHt on page 142
CALCulate<n>:MARKer<m>:MAXimum:LEFT on page 141
CALCulate<n>:DELTamarker<m>:MAXimum:NEXT on page 143
CALCulate<n>:DELTamarker<m>:MAXimum:RIGHt on page 144
CALCulate<n>:DELTamarker<m>:MAXimum:LEFT on page 143
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 142
CALCulate<n>:DELTamarker<m>:MINimum[:PEAK] on page 145
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.
Remote command:
CALCulate<n>:MARKer<m>:MINimum:NEXT on page 142
CALCulate<n>:MARKer<m>:MINimum:LEFT on page 142
CALCulate<n>:MARKer<m>:MINimum:RIGHt on page 143
CALCulate<n>:DELTamarker<m>:MINimum:NEXT on page 144
CALCulate<n>:DELTamarker<m>:MINimum:LEFT on page 144
CALCulate<n>:DELTamarker<m>:MINimum:RIGHt on page 145
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6.4 Export functions
Analysis
Export functions
Access: "Save" > "Export"
The standard data management functions (e.g. saving or loading instrument settings)
that are available for all R&S FSW applications are not described here.
See the R&S FSW User Manual for a description of the standard functions.
Export table to ASCII File..............................................................................................80
Table Export Configuration............................................................................................80
└ Include Instrument & Measurement Settings..................................................80
└ Decimal Separator.......................................................................................... 81
└ Export Table to ASCII File...............................................................................81
Export Trace to ASCII File.............................................................................................81
Trace Export Configuration........................................................................................... 81
└ Include Instrument & Measurement Settings..................................................81
└ Decimal Separator.......................................................................................... 81
└ Export Trace to ASCII File.............................................................................. 82
I/Q Export......................................................................................................................82
└ File Explorer....................................................................................................82
Export table to ASCII File
Opens a file selection dialog box and saves the selected result table in ASCII format
(.DAT) to the specified file and directory.
Note: To store the measurement results for all traces and tables in all windows, use
the Export Trace to ASCII File command in the "Save/Recall" > "Export" menu.
(See also "Trace Export Configuration" on page 81)
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>:TABLe on page 157
Table Export Configuration
Table results can be exported to an ASCII file for further evaluation in other (external)
applications.
Include Instrument & Measurement Settings ← Table Export Configuration
Includes additional instrument and measurement settings in the header of the export
file for result data.
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Export functions
Remote command:
FORMat:DEXPort:HEADer on page 159
Decimal Separator ← Table Export Configuration
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 159
Export Table to ASCII File ← Table Export Configuration
Opens a file selection dialog box and saves the selected result table in ASCII format
(.DAT) to the specified file and directory.
See "Export table to ASCII File" on page 80.
Export Trace to ASCII File
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.
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 158
Trace Export Configuration
Opens the "Traces" dialog box to configure the trace and data export settings.
Include Instrument & Measurement Settings ← Trace Export Configuration
Includes additional instrument and measurement settings in the header of the export
file for result data.
Remote command:
FORMat:DEXPort:HEADer on page 159
Decimal Separator ← Trace Export Configuration
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 159
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Analysis
Export functions
Export Trace to ASCII File ← Trace Export Configuration
Opens a file selection dialog box and saves the selected trace in ASCII format (.dat)
to the specified file and directory.
See "Export Trace to ASCII File" on page 81.
I/Q Export
Opens a file selection dialog box to define an export file name to which the I/Q data is
stored. This function is only available in single sweep mode.
Note: Storing large amounts of I/Q data (several Gigabytes) can exceed the available
(internal) storage space on the R&S FSW. In this case, it can be necessary to use an
external storage medium.
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.
File Explorer ← I/Q Export
Opens the Microsoft Windows File Explorer.
Remote command:
not supported
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7 How to perform VOR/ILS measurements
How to perform VOR/ILS measurements
The following step-by-step instructions demonstrate how to perform an VOR/ILS measurement with the R&S FSW Avionics (VOR/ILS) measurements application.
1. Press the [MODE] key on the front panel and select the "Avionics" application.
2. Press the "MEAS" key and select the required measurement type (ILS/VOR).
3. Select the "Overview" softkey to display the "Overview" for a VOR/ILS measurement.
4. Select "Input/Frontend" and switch to the "Frequency" tab.
5. Define the center frequency and any known frequency offset.
6. Select the "Amplitude" tab and define the appropriate reference level to avoid overload and underload. The bargraph in the Signal Summary is a useful indicator
whether the selected value is suitable or not. The bar should cover as much of the
graph as possible.
7. Select the "Data Acquisition" button and define the frequency range ("Demodulation BW") and duration ("Measurement Time") of the measurement.
Make sure the bandwidth covers all relevant parts of the signal, but no more. If you
are interested in the identifier, the measurement time must be long enough to capture the entire IDENT component (several seconds).
8. Select the "Display Config" button and select the displays that are of interest to you
(up to 6).
Arrange them on the display to suit your preferences.
9. Press [ESC] to exit the display configuration.
10. Stop the continuous sweep and start a new sweep with the new configuration (e.g.
using the [RUN SINGLE] key).
The characteristic signal parameters and distortion results are displayed.
11. Select the "Spectrum" softkey from the main "Avionics" menu to obtain the distortion for a particular frequency.
a) Define the frequency ("Harmonic Freq") at which the distortion is to be calcula-
ted.
b) Define the fundamental frequency to be used as a reference for the distortion
measurement.
The distortion at the selected frequency is indicated in the marker area of the
"Modulation Spectrum" display ("DIST").
12. Select the "Result Config" softkey from the main "Avionics" menu to change any
units for the result displays.
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8 Optimizing and troubleshooting the mea-
Optimizing and troubleshooting the measurement
surement
If the results do not meet your expectations, try the following methods to optimize the
measurement or solve problems.
Problem: No identification signal results at all in ILS Result Summary.........................84
Problem: Identification signal results are unstable or missing in the Result Summary
...................................................................................................................................... 84
Problem: No Morse coding results................................................................................84
Problem: Modulation Spectrum display shows picket fence effect around identification
signal.............................................................................................................................85
Problem: Modulation Spectrum display does not resolve the signal components........ 85
Problem: Modulation Spectrum display shows strange distortion products (VOR mea-
surement)......................................................................................................................85
Problem: Values in Result Summary or Signal Summary not accurate enough........... 85
Problem: identification code not as expected................................................................85
Problem: Missing results in Distortion Summary...........................................................85
Problem: K2 and K3 cannot be calculated....................................................................85
Problem: No identification signal results at all in ILS Result Summary
A demodulation bandwidth of 800 Hz does not allow for identification signals to be
demodulated. Select a larger demodulation bandwidth (see Chapter 5.4, "Data acquisi-
tion and detection", on page 62).
Explanation: The maximum AF frequency that can be analyzed is 0.5 * Demodulation
BW = 400 Hz (for carrier offset = 0 Hz and DBW = 800 Hz). However, the identification/
voice signal is 300 Hz to 4000 Hz, typically 1020 Hz.
Problem: Identification signal results are unstable or missing in the Result Summary
Possible Solutions:
●
Turn off Morse coding of the identification signal in your DUT (making the signal a
continuous tone)
●
Increase the measurement time of the R&S FSW Avionics (VOR/ILS) measurements application to make sure at least one ON period is included, even in the
worst case
●
Synchronize the R&S FSW Avionics (VOR/ILS) measurements application and the
DUT's Morse coding using an external trigger on the R&S FSW.
Problem: No Morse coding results
Possible Solution: Increase the measurement time of the R&S FSW Avionics (VOR/
ILS) measurements application. It should be at least the repetition cycle time of the
Morse signal plus the time required to transmit two characters.
If time cannot be increased: Lower the demodulation bandwidth
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Optimizing and troubleshooting the measurement
Problem: Modulation Spectrum display shows picket fence effect around identification signal
Possible Solution: Turn off Morse coding of the identification signal in your DUT
(making the signal a continuous tone), or turn off the identification signal in your DUT
altogether.
Problem: Modulation Spectrum display does not resolve the signal components
Possible Solution: Make sure the RBW is small enough to distinguish all compo-
nents. If possible, use the RBW auto mode (see "RBW" on page 64).
Problem: Modulation Spectrum display shows strange distortion products (VOR
measurement)
Possible Solution: Could be FM to AM conversion, caused by FM signals or FM-like
distortion products falling onto the application's digital filter's slope. Increase the
Demodulation BW so that the critical frequencies fall into the filter's flat passband. Also
check the measured carrier offset and adjust the carrier frequency setting either in the
R&S FSW Avionics (VOR/ILS) measurements application or on the DUT.
Problem: Values in Result Summary or Signal Summary not accurate enough
Possible Solutions:
●
Increase the measurement time.
●
Adjust the reference level.
Use an external reference frequency, if possible.
(See the Reference Frequency Settings chapter in the R&S FSW User Manual).
Problem: identification code not as expected
That is OK if DUT and R&S FSW Avionics (VOR/ILS) measurements application are
not synchronized. Sending "MUC" can give you "C MU" or "UC MU" or "UC MU", etc.
Possible Solution: Increase the measurement time to get the complete code
word, .e.g "UC MUC MU".
Problem: Missing results in Distortion Summary
K2, K3, and THD of a signal can only be measured if its modulation depth was detected to be high enough to trust the estimated frequency.
Possible Solutions:
●
In your DUT, turn on the missing signal or increase its modulation depth.
●
The THD result cannot be calculated if the Distortion Max Frequency parameter is
smaller than 2 times the fundamental frequency. Increase the Distortion Max Fre-
quency.
Note that the AF Span defined for the Modulation Spectrum result display has no effect
on the THD, K2 and K3 results.
Problem: K2 and K3 cannot be calculated
Possible Solution:
K2 and K3 do not regard the Distortion Max Frequency parameter, but cannot be calculated if the span of the Modulation Spectrum display ends earlier than 2 or 3 times
the fundamental frequency, respectively. Increase the demodulation bandwidth.
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Optimizing and troubleshooting the measurement
Note that the AF Span defined for the Modulation Spectrum result display has no effect
on the THD, K2 and K3 results.
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9 Remote commands to perform VOR/ILS
Remote commands to perform VOR/ILS measurements
measurements
The following commands are required to perform measurements in the R&S FSW
Avionics (VOR/ILS) measurements application in a remote environment. It is assumed
that the R&S FSW has already been set up for remote operation in a network as
described in the R&S FSW User Manual.
Common Suffixes
In the R&S FSW Avionics (VOR/ILS) measurements application, the following common
suffixes are used in remote commands:
Table 9-1: Common suffixes used in remote commands in the R&S FSW Avionics (VOR/ILS) measure-
Suffix Value range Description
<m> 1 to 13 Marker
<n> 1 to 16 Window (in the currently selected channel)
<t> 1 to 6 Trace
<li> 1 to 8 Limit line
Note that basic tasks that are also performed in the base unit in the same way are not
described here. For a description of such tasks, see the R&S FSW User Manual.
In particular, this includes:
●
●
●
The following tasks specific to the R&S FSW Avionics (VOR/ILS) measurements application are described here:
● Introduction............................................................................................................. 88
● Activating VOR/ILS measurements.........................................................................92
● Selecting the measurement type.............................................................................96
● Configuring VOR/ILS measurements......................................................................97
● Configuring and performing sweeps..................................................................... 121
● Analyzing VOR/ILS measurements.......................................................................123
● Retrieving results.................................................................................................. 146
● Status reporting system........................................................................................ 160
● Programming examples: performing VOR/ILS measurements.............................163
ments application
Managing Settings and Results, i.e. storing and loading settings and result data
Basic instrument configuration, e.g. checking the system configuration, customizing
the screen layout, or configuring networks and remote operation
Using the common status registers
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9.1 Introduction
Remote commands to perform VOR/ILS measurements
Introduction
Commands are program messages that a controller (e.g. a PC) sends to the instrument or software. They operate its functions ('setting commands' or 'events') and
request information ('query commands'). Some commands can only be used in one
way, others work in two ways (setting and query). If not indicated otherwise, the commands can be used for settings and queries.
The syntax of a SCPI command consists of a header and, usually, one or more parameters. To use a command as a query, you have to append a question mark after the
last header element, even if the command contains a parameter.
A header contains one or more keywords, separated by a colon. Header and parameters are separated by a "white space" (ASCII code 0 to 9, 11 to 32 decimal, e.g. blank).
If there is more than one parameter for a command, they are separated by a comma
from one another.
Only the most important characteristics that you need to know when working with SCPI
commands are described here. For a more complete description, refer to the user
manual of the R&S FSW.
Remote command examples
Note that some remote command examples mentioned in this general introduction are
possibly not supported by this particular application.
9.1.1 Conventions used in descriptions
The following conventions are used in the remote command descriptions:
●
Command usage
If not specified otherwise, commands can be used both for setting and for querying
parameters.
If a command can be used for setting or querying only, or if it initiates an event, the
usage is stated explicitly.
●
Parameter usage
If not specified otherwise, a parameter can be used to set a value and it is the
result of a query.
Parameters required only for setting are indicated as Setting parameters.
Parameters required only to refine a query are indicated as Query parameters.
Parameters that are only returned as the result of a query are indicated as Return
values.
●
Conformity
Commands that are taken from the SCPI standard are indicated as SCPI confirmed. All commands used by the R&S FSW follow the SCPI syntax rules.
●
Asynchronous commands
A command which does not automatically finish executing before the next command starts executing (overlapping command) is indicated as an Asynchronous
command.
●
Reset values (*RST)
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9.1.2 Long and short form
Remote commands to perform VOR/ILS measurements
Introduction
Default parameter values that are used directly after resetting the instrument (*RST
command) are indicated as *RST values, if available.
●
Default unit
The default unit is used for numeric values if no other unit is provided with the
parameter.
●
Manual operation
If the result of a remote command can also be achieved in manual operation, a link
to the description is inserted.
The keywords have a long and a short form. You can use either the long or the short
form, but no other abbreviations of the keywords.
The short form is emphasized in uppercase letters. Note however, that this emphasis
only serves the purpose to distinguish the short from the long form in the manual. For
the instrument, the case does not matter.
Example:
SENSe:FREQuency:CENTer is the same as SENS:FREQ:CENT.
9.1.3 Numeric suffixes
Some keywords have a numeric suffix if the command can be applied to multiple
instances of an object. In that case, the suffix selects a particular instance (e.g. a measurement window).
Numeric suffixes are indicated by angular brackets (<n>) next to the keyword.
If you do not quote a suffix for keywords that support one, a 1 is assumed.
Example:
DISPlay[:WINDow<1...4>]:ZOOM:STATe enables the zoom in a particular measurement window, selected by the suffix at WINDow.
DISPlay:WINDow4:ZOOM:STATe ON refers to window 4.
9.1.4 Optional keywords
Some keywords are optional and are only part of the syntax because of SCPI compliance. You can include them in the header or not.
If an optional keyword has a numeric suffix and you need to use the suffix, you have to
include the optional keyword. Otherwise, the suffix of the missing keyword is assumed
to be the value 1.
Optional keywords are emphasized with square brackets.
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9.1.5 Alternative keywords
Remote commands to perform VOR/ILS measurements
Introduction
Example:
Without a numeric suffix in the optional keyword:
[SENSe:]FREQuency:CENTer is the same as FREQuency:CENTer
With a numeric suffix in the optional keyword:
DISPlay[:WINDow<1...4>]:ZOOM:STATe
DISPlay:ZOOM:STATe ON enables the zoom in window 1 (no suffix).
DISPlay:WINDow4:ZOOM:STATe ON enables the zoom in window 4.
A vertical stroke indicates alternatives for a specific keyword. You can use both keywords to the same effect.
Example:
[SENSe:]BANDwidth|BWIDth[:RESolution]
In the short form without optional keywords, BAND 1MHZ would have the same effect
as BWID 1MHZ.
9.1.6 SCPI parameters
Many commands feature one or more parameters.
If a command supports more than one parameter, they are separated by a comma.
Example:
LAYout:ADD:WINDow Spectrum,LEFT,MTABle
Parameters can have different forms of values.
● Numeric values....................................................................................................... 90
● Boolean...................................................................................................................91
● Character data........................................................................................................ 92
● Character strings.....................................................................................................92
● Block data............................................................................................................... 92
9.1.6.1 Numeric values
Numeric values can be entered in any form, i.e. with sign, decimal point or exponent.
For physical quantities, you can also add the unit. If the unit is missing, the command
uses the basic unit.
Example:
With unit: SENSe:FREQuency:CENTer 1GHZ
Without unit: SENSe:FREQuency:CENTer 1E9 would also set a frequency of 1 GHz.
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Remote commands to perform VOR/ILS measurements
Introduction
Values exceeding the resolution of the instrument are rounded up or down.
If the number you have entered is not supported (e.g. for discrete steps), the command
returns an error.
Instead of a number, you can also set numeric values with a text parameter in special
cases.
●
MIN/MAX
Defines the minimum or maximum numeric value that is supported.
●
DEF
Defines the default value.
●
UP/DOWN
Increases or decreases the numeric value by one step. The step size depends on
the setting. Sometimes, you can customize the step size with a corresponding
command.
Querying numeric values
When you query numeric values, the system returns a number. For physical quantities,
it applies the basic unit (e.g. Hz for frequencies). The number of digits after the decimal
point depends on the type of numeric value.
Example:
Setting: SENSe:FREQuency:CENTer 1GHZ
Query: SENSe:FREQuency:CENTer? would return 1E9
Sometimes, numeric values are returned as text.
●
INF/NINF
Infinity or negative infinity. Represents the numeric values 9.9E37 or -9.9E37.
●
NAN
Not a number. Represents the numeric value 9.91E37. NAN is returned if errors
occur.
9.1.6.2 Boolean
Boolean parameters represent two states. The "on" state (logically true) is represented
by "ON" or the numeric value 1. The "off" state (logically untrue) is represented by
"OFF" or the numeric value 0.
Querying Boolean parameters
When you query Boolean parameters, the system returns either the value 1 ("ON") or
the value 0 ("OFF").
Example:
Setting: DISPlay:WINDow:ZOOM:STATe ON
Query: DISPlay:WINDow:ZOOM:STATe? would return 1
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9.1.6.3 Character data
9.1.6.4 Character strings
Remote commands to perform VOR/ILS measurements
Activating VOR/ILS measurements
Character data follows the syntactic rules of keywords. You can enter text using a short
or a long form. For more information, see Chapter 9.1.2, "Long and short form",
on page 89.
Querying text parameters
When you query text parameters, the system returns its short form.
Example:
Setting: SENSe:BANDwidth:RESolution:TYPE NORMal
Query: SENSe:BANDwidth:RESolution:TYPE? would return NORM
Strings are alphanumeric characters. They have to be in straight quotation marks. You
can use a single quotation mark ( ' ) or a double quotation mark ( " ).
Example:
INSTRument:DELete 'Spectrum'
9.1.6.5 Block data
Block data is a format which is suitable for the transmission of large amounts of data.
The ASCII character # introduces the data block. The next number indicates how many
of the following digits describe the length of the data block. The data bytes follow. During the transmission of these data bytes, all end or other control signs are ignored until
all bytes are transmitted. #0 specifies a data block of indefinite length. The use of the
indefinite format requires an NL^END message to terminate the data block. This format
is useful when the length of the transmission is not known or if speed or other considerations prevent segmentation of the data into blocks of definite length.
9.2 Activating VOR/ILS measurements
VOR/ILS measurements require a special application on the R&S FSW. A measurement is started immediately with the default settings.
INSTrument:CREate[:NEW].............................................................................................. 93
INSTrument:CREate:REPLace..........................................................................................93
INSTrument:DELete......................................................................................................... 93
INSTrument:LIST?........................................................................................................... 94
INSTrument:REName.......................................................................................................95
INSTrument[:SELect]........................................................................................................96
SYSTem:PRESet:CHANnel[:EXEC]................................................................................... 96
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Remote commands to perform VOR/ILS measurements
Activating VOR/ILS measurements
INSTrument:CREate[:NEW] <ChannelType>, <ChannelName>
This command adds a measurement channel. You can configure up to 10 measurement channels at the same time (depending on available memory).
Parameters:
<ChannelType> Channel type of the new channel.
For a list of available channel types, see INSTrument:LIST?
on page 94.
<ChannelName> String containing the name of the channel.
Note that you cannot assign an existing channel name to a new
channel. If you do, an error occurs.
Example:
INSTrument:CREate:REPLace <ChannelName1>,<ChannelType>,<ChannelName2>
This command replaces a channel with another one.
Setting parameters:
<ChannelName1> String containing the name of the channel you want to replace.
<ChannelType> Channel type of the new channel.
<ChannelName2> String containing the name of the new channel.
Example:
INST:CRE SAN, 'Spectrum 2'
Adds a spectrum display named "Spectrum 2".
For a list of available channel types, see INSTrument:LIST?
on page 94.
Note: If the specified name for a new channel already exists, the
default name, extended by a sequential number, is used for the
new channel (see INSTrument:LIST? on page 94).
Channel names can have a maximum of 31 characters, and
must be compatible with the Windows conventions for file
names. In particular, they must not contain special characters
such as ":", "*", "?".
INST:CRE:REPL 'IQAnalyzer2',IQ,'IQAnalyzer'
Replaces the channel named "IQAnalyzer2" by a new channel of
type "IQ Analyzer" named "IQAnalyzer".
Usage: Setting only
INSTrument:DELete <ChannelName>
This command deletes a channel.
If you delete the last channel, the default "Spectrum" channel is activated.
Setting parameters:
<ChannelName> String containing the name of the channel you want to delete.
A channel must exist to delete it.
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Remote commands to perform VOR/ILS measurements
Activating VOR/ILS measurements
Example:
INST:DEL 'IQAnalyzer4'
Deletes the channel with the name 'IQAnalyzer4'.
Usage: Setting only
INSTrument:LIST?
This command queries all active channels. The query is useful to obtain the names of
the existing channels, which are required to replace or delete the channels.
Return values:
<ChannelType>,
<ChannelName>
For each channel, the command returns the channel type and
channel name (see tables below).
Tip: to change the channel name, use the INSTrument:
REName command.
Example:
INST:LIST?
Result for 3 channels:
'ADEM','Analog Demod','IQ','IQ
Analyzer','IQ','IQ Analyzer2'
Usage: Query only
Table 9-2: Available channel types and default channel names in Signal and Spectrum Analyzer mode
Application <ChannelType>
parameter
Default Channel name*)
Spectrum SANALYZER Spectrum
1xEV-DO BTS (R&S FSW-K84) BDO 1xEV-DO BTS
1xEV-DO MS (R&S FSW-K85) MDO 1xEV-DO MS
3GPP FDD BTS (R&S FSW-K72) BWCD 3G FDD BTS
3GPP FDD UE (R&S FSW-K73) MWCD 3G FDD UE
802.11ad (R&S FSW-K95) WIGIG 802.11ad
802.11ay (R&S FSW-K97) EDMG 802.11ay EDMG
Amplifier Measurements (R&S FSW-K18) AMPLifier Amplifier
AM/FM/PM Modulation Analysis (R&S FSW-K7) ADEM Analog Demod
Avionics (R&S FSW-K15) AVIonics Avionics
cdma2000 BTS (R&S FSW-K82) BC2K CDMA2000 BTS
cdma2000 MS (R&S FSW-K83) MC2K CDMA2000 MS
DOCSIS 3.1 (R&S FSW-K192/193) DOCSis DOCSIS 3.1
Fast Spur Search (R&S FSW-K50) SPUR Spurious
GSM (R&S FSW-K10) GSM GSM
HRP UWB (R&S FSW-K149) UWB HRP UWB
*) If the specified name for a new channel already exists, the default name, extended by a sequential number, is used for the new channel.
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Remote commands to perform VOR/ILS measurements
Activating VOR/ILS measurements
Application <ChannelType>
parameter
I/Q Analyzer IQ IQ Analyzer
LTE (R&S FSW-K10x) LTE LTE
Multi-Carrier "Group Delay" (R&S FSW-K17) MCGD MC "Group Delay"
NB-IoT (R&S FSW-K106) NIOT NB-IoT
Noise (R&S FSW-K30) NOISE Noise
5G NR (R&S FSW-K144) NR5G 5G NR
OFDM VSA (R&S FSW-K96) OFDMVSA OFDM VSA
OneWeb (R&S FSW-K201) OWEB OneWeb
Phase Noise (R&S FSW-K40) PNOISE Phase Noise
Pulse (R&S FSW-K6) PULSE Pulse
"Real-Time Spectrum" RTIM "Real-Time Spectrum"
TD-SCDMA BTS (R&S FSW-K76) BTDS TD-SCDMA BTS
TD-SCDMA UE (R&S FSW-K77) MTDS TD-SCDMA UE
Transient Analysis (R&S FSW-K60) TA Transient Analysis
Default Channel name*)
Verizon 5GTF Measurement Application (V5GTF,
R&S FSW-K118)
VSA (R&S FSW-K70) DDEM VSA
WLAN (R&S FSW-K91) WLAN WLAN
*) If the specified name for a new channel already exists, the default name, extended by a sequential number, is used for the new channel.
V5GT V5GT
INSTrument:REName <ChannelName1>, <ChannelName2>
This command renames a channel.
Setting parameters:
<ChannelName1> String containing the name of the channel you want to rename.
<ChannelName2> String containing the new channel name.
Note that you cannot assign an existing channel name to a new
channel. If you do, an error occurs.
Channel names can have a maximum of 31 characters, and
must be compatible with the Windows conventions for file
names. In particular, they must not contain special characters
such as ":", "*", "?".
Example:
INST:REN 'IQAnalyzer2','IQAnalyzer3'
Renames the channel with the name 'IQAnalyzer2' to 'IQAnalyzer3'.
Usage: Setting only
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Remote commands to perform VOR/ILS measurements
Selecting the measurement type
INSTrument[:SELect] <ChannelType>
This command activates a new measurement channel with the defined channel type,
or selects an existing measurement channel with the specified name.
See also INSTrument:CREate[:NEW] on page 93.
For a list of available channel types see INSTrument:LIST? on page 94.
Parameters:
<ChannelType> AVI
R&S FSW Avionics (VOR/ILS) measurements application,
R&S FSW–K15
Example:
SYSTem:PRESet:CHANnel[:EXEC]
This command restores the default instrument settings in the current channel.
Use INST:SEL to select the channel.
Example:
Usage: Event
Manual operation: See "Preset Channel" on page 43
INST:SEL AVI
INST:SEL 'Spectrum2'
Selects the channel for "Spectrum2".
SYST:PRES:CHAN:EXEC
Restores the factory default settings to the "Spectrum2" channel.
9.3 Selecting the measurement type
CALCulate<n>:AVIonics[:STANdard] <Standard>
Defines the standard for which the signal parameters are measured.
For details on the standards and the corresponding measurements see Chapter 4,
"Measurements and result displays", on page 28 and Chapter 3.1, "General information on ILS and VOR/DVOR", on page 13.
Suffix:
<n>
Parameters:
<Standard> VOR | ILS
Example:
Manual operation: See "Select Measurement" on page 44
.
1..n
irrelevant
*RST: VOR
CALC:AVI:STAN ILS
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9.4 Configuring VOR/ILS measurements
9.4.1 Input source settings
Remote commands to perform VOR/ILS measurements
Configuring VOR/ILS measurements
● Input source settings...............................................................................................97
● Configuring the outputs.........................................................................................102
● Frontend configuration.......................................................................................... 103
● Triggering measurements..................................................................................... 109
● Data acquisition.....................................................................................................116
● Configuring the demodulation spectrum................................................................119
INPut<ip>:ATTenuation:PROTection:RESet.........................................................................97
INPut<ip>:CONNector...................................................................................................... 97
INPut<ip>:COUPling.........................................................................................................98
INPut<ip>:DPATh.............................................................................................................98
INPut<ip>:FILE:PATH.......................................................................................................99
INPut<ip>:FILTer:HPASs[:STATe].....................................................................................100
INPut<ip>:FILTer:YIG[:STATe]..........................................................................................100
INPut<ip>:IMPedance.....................................................................................................100
INPut<ip>:SELect...........................................................................................................101
INPut<ip>:TYPE............................................................................................................ 101
TRACe:IQ:FILE:REPetition:COUNt..................................................................................102
INPut<ip>:ATTenuation:PROTection:RESet
This command resets the attenuator and reconnects the RF input with the input mixer
for the R&S FSW after an overload condition occurred and the protection mechanism
intervened. The error status bit (bit 3 in the STAT:QUES:POW status register) and the
INPUT OVLD message in the status bar are cleared.
The command works only if the overload condition has been eliminated first.
Suffix:
<ip>
.
1 | 2
For R&S FSW85 models with two RF input connectors:
1: Input 1 (1 mm [RF Input] connector)
2: Input 2 (1.85 mm [RF2 Input] connector)
For all other models:
irrelevant
Example:
INP:ATT:PROT:RES
INPut<ip>:CONNector <ConnType>
Determines which connector the input for the measurement is taken from.
If an external frontend is active, the connector is automatically set to RF.
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Remote commands to perform VOR/ILS measurements
Configuring VOR/ILS measurements
Suffix:
<ip>
Parameters:
<ConnType> RF
Example:
Manual operation: See "Input Connector" on page 47
INPut<ip>:COUPling <CouplingType>
This command selects the coupling type of the RF input.
Suffix:
<ip>
Parameters:
<CouplingType> AC | DC
.
1 | 2
irrelevant
RF input connector
RFPRobe
Active RF probe
*RST: RF
INP:CONN RF
Selects input from the RF input connector.
.
1 | 2
irrelevant
AC
AC coupling
DC
DC coupling
*RST: AC
Example:
Manual operation: See "Input Coupling" on page 46
INPut<ip>:DPATh <DirectPath>
Enables or disables the use of the direct path for frequencies close to 0 Hz.
Suffix:
<ip>
Parameters:
<DirectPath> AUTO | OFF
INP:COUP DC
.
1 | 2
irrelevant
AUTO | 1
(Default) the direct path is used automatically for frequencies
close to 0 Hz.
OFF | 0
The analog mixer path is always used.
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Remote commands to perform VOR/ILS measurements
Configuring VOR/ILS measurements
Example:
INP:DPAT OFF
Manual operation: See "Direct Path" on page 46
INPut<ip>:FILE:PATH <FileName>[, <AnalysisBW>]
This command selects the I/Q data file to be used as input for further measurements.
The I/Q data file must be in one of the following supported formats:
.iq.tar
●
.iqw
●
.csv
●
.mat
●
.wv
●
.aid
●
Only a single data stream or channel can be used as input, even if multiple streams or
channels are stored in the file.
For some file formats that do not provide the sample rate and measurement time or
record length, you must define these parameters manually. Otherwise the traces are
not visible in the result displays.
Suffix:
<ip>
.
1 | 2
irrelevant
Parameters:
<FileName> String containing the path and name of the source file.
The file extension is *.iq.tar.
<AnalysisBW> Optionally: The analysis bandwidth to be used by the measure-
ment. The bandwidth must be smaller than or equal to the bandwidth of the data that was stored in the file.
Default unit: HZ
Example:
INP:FILE:PATH 'C:\R_S\Instr\user\data.iq.tar'
Uses I/Q data from the specified file as input.
Example:
//Load an IQW file
INP:SEL:FIQ
INP:FILE:PATH 'C:\R_S\Instr\user\data.iqw'
//Define the sample rate
TRAC:IQ:SRAT 10MHz
//Define the measurement time
SENSe:SWEep:TIME 0.001001
//Start the measurement
INIT:IMM
Manual operation: See "Select I/Q data file" on page 48
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Remote commands to perform VOR/ILS measurements
Configuring VOR/ILS measurements
INPut<ip>:FILTer:HPASs[:STATe] <State>
Activates an additional internal high-pass filter for RF input signals from 1 GHz to
3 GHz. This filter is used to remove the harmonics of the R&S FSW to measure the
harmonics for a DUT, for example.
This function requires an additional high-pass filter 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.)
Suffix:
<ip>
Parameters:
<State> ON | OFF | 0 | 1
Example:
Manual operation: See "High Pass Filter 1 to 3 GHz" on page 47
INPut<ip>:FILTer:YIG[:STATe] <State>
Enables or disables the YIG filter.
Suffix:
<ip>
.
1 | 2
irrelevant
OFF | 0
Switches the function off
ON | 1
Switches the function on
*RST: 0
INP:FILT:HPAS ON
Turns on the filter.
.
1 | 2
irrelevant
Parameters:
<State> ON | OFF | 0 | 1
Example:
Manual operation: See "YIG-Preselector" on page 47
INPut<ip>:IMPedance <Impedance>
This command selects the nominal input impedance of the RF input. In some applications, only 50 Ω are supported.
Suffix:
<ip>
INP:FILT:YIG OFF
Deactivates the YIG-preselector.
.
1 | 2
irrelevant
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