Satellite Navigation
R&S®SMW-K44/-K66/-K94/-K99/-
K106/-K107/-K108/-K120
User Manual
GPS, Galileo, GLONASS, BeiDou,
SBAS/QZSS, GNSS Extension, Real
word simulation, Advanced mode
(;ÜÍÝ2)
1178.6379.02 ─ 01
User Manual
Described are the following software options:
●
R&S®SMW-K44/-K66/-K94/-K107/-K106/-K99/-K108/-K120
This manual describes firmware version FW 4.15.048.xx and later of the R&S®SMW200A.
© 2017 Rohde & Schwarz GmbH & Co. KG
Mühldorfstr. 15, 81671 München, Germany
Phone: +49 89 41 29 - 0
Fax: +49 89 41 29 12 164
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 their owners.
Throughout this manual, products from Rohde & Schwarz are indicated without the ® symbol, e.g. R&S®SMW200A is indicated as
R&S SMW
ContentsSatellite Navigation
Contents
1 Preface.................................................................................................... 9
1.1 About this Manual......................................................................................................... 9
1.2 Documentation Overview........................................................................................... 10
1.2.1 Getting Started Manual................................................................................................. 10
1.2.2 User Manuals and Help.................................................................................................10
1.2.3 Tutorials........................................................................................................................ 10
1.2.4 Service Manual............................................................................................................. 11
1.2.5 Instrument Security Procedures....................................................................................11
1.2.6 Basic Safety Instructions...............................................................................................11
1.2.7 Data Sheets and Brochures.......................................................................................... 11
1.2.8 Release Notes and Open Source Acknowledgment (OSA).......................................... 11
1.2.9 Application Notes, Application Cards, White Papers, etc..............................................11
2 Welcome to the GNSS Satellite Navigation Options.........................12
2.1 Accessing the GNSS Dialog.......................................................................................13
2.2 Scope........................................................................................................................... 13
3 Required Options.................................................................................14
4 About GNSS..........................................................................................15
4.1 GNSS Systems Overview........................................................................................... 15
4.2 SBAS Overview........................................................................................................... 17
4.3 GNSS Components Overview.................................................................................... 17
4.4 How Are the GNSS Components Simulated?...........................................................19
5 Getting Started..................................................................................... 21
5.1 Trying Out the GNSS Simulator.................................................................................21
5.2 General Settings..........................................................................................................23
5.3 Simulation Monitor......................................................................................................26
6 Simulation Time................................................................................... 35
6.1 Time Configuration Settings...................................................................................... 35
7 Receiver Type and Position................................................................ 40
7.1 Receiver Type..............................................................................................................40
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7.2 Static Receiver............................................................................................................ 42
7.3 Moving Receiver..........................................................................................................46
8 Satellite's Constellation.......................................................................51
8.1 Systems and Signals Settings................................................................................... 52
8.2 Satellites Settings....................................................................................................... 54
9 Space Vehicle Configuration.............................................................. 61
9.1 Power Settings............................................................................................................ 62
9.2 Modulation Control Settings...................................................................................... 66
9.3 Simulated Orbit and Orbit Perturbation Settings.....................................................70
9.4 Simulated Clock Settings........................................................................................... 77
10 Real-World Environment..................................................................... 81
10.1 Required Options........................................................................................................ 81
10.2 Spinning and Attitude Simulation..............................................................................82
10.3 Antenna Pattern and Body Mask............................................................................... 82
10.4 Supported Multipath Models......................................................................................85
10.5 How to Simulate Real-Word Effects.......................................................................... 85
10.5.1 Visualizing the Effect of an Antenna Pattern.................................................................85
10.6 Antenna Configuration Settings................................................................................ 87
10.7 Environment Model and Environment Configuration..............................................92
10.8 Static Multipath........................................................................................................... 92
11 Tracking Mode......................................................................................96
11.1 Signal Dynamics Settings.......................................................................................... 96
12 Perturbations and Errors Simulation............................................... 101
12.1 About the Errors Sources........................................................................................ 101
12.1.1 About the Atmospheric Effects....................................................................................102
12.1.2 About Orbit and Orbit Perturbation Parameters and Errors........................................ 102
12.1.3 About Clock and Time Conversion Parameters and Errors........................................ 104
12.1.4 Simulating Errors.........................................................................................................105
12.1.5 Errors Compensation.................................................................................................. 106
12.2 Atmospheric Effects and Ionospheric Errors Settings......................................... 106
12.3 Pseudorange Errors Settings.................................................................................. 114
12.4 Orbit and Orbit Perturbation Errors Settings......................................................... 117
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12.5 Clock Errors Settings............................................................................................... 124
12.6 Time Conversion Errors Settings............................................................................ 127
12.7 System Errors Settings............................................................................................ 131
13 SBAS Corrections..............................................................................135
13.1 About SBAS...............................................................................................................135
13.2 About Errors Correction...........................................................................................136
13.3 How to Generate SBAS Corrections....................................................................... 138
13.4 SBAS Settings........................................................................................................... 140
13.4.1 Error Correction Mode.................................................................................................140
13.4.2 GEO Ranging Information...........................................................................................142
13.4.2.1 Simulated Orbit and Simulated Clock Settings........................................................... 143
13.4.2.2 Broadcasted Orbit, Clock and Time Conversion Settings........................................... 144
13.4.3 Differential Corretions................................................................................................. 147
13.4.3.1 Timing Setting of the Differential Corrections..............................................................148
13.4.3.2 Ionosphere Grid Settings............................................................................................ 149
13.4.3.3 PRN Mask Settings..................................................................................................... 151
13.4.3.4 Fast Correction Settings..............................................................................................152
13.4.3.5 Long-Term Correction File Configuration Settings......................................................155
13.4.3.6 Fast Correction Degradation Factor Configuration Settings....................................... 156
13.4.3.7 Clock-Ephemeris Covariance Matrix Configuration Settings...................................... 158
13.4.4 Additional SBAS System Parameters......................................................................... 159
14 Multi-Band, Multi-Antenna and Multi-Vehicle Scenarios................164
14.1 Related Settings........................................................................................................ 166
14.2 Output Streams......................................................................................................... 167
15 Data Logging...................................................................................... 171
15.1 Data Logging General Settings................................................................................173
15.2 Configure Logging Settings.....................................................................................175
16 Assistance Data Generation............................................................. 180
17 Loading Historical Data.....................................................................190
17.1 Import GNSS Constellation and Navigation Message Data Settings................... 192
17.2 Import SBAS Constellation and Correction Data Settings....................................193
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18 Signal Generation Control.................................................................195
18.1 Trigger Settings.........................................................................................................195
18.2 Marker Settings......................................................................................................... 200
18.3 Clock Settings........................................................................................................... 202
18.4 Local and Global Connector Settings..................................................................... 203
19 Remote-Control Commands............................................................. 204
19.1 Programming Examples........................................................................................... 206
19.2 General Settings........................................................................................................206
19.3 Systems and Signals................................................................................................ 211
19.4 Time Conversion Configuration.............................................................................. 214
19.5 Receiver Positioning Configuration Commands................................................... 225
19.6 Antenna Pattern and Body Mask............................................................................. 233
19.7 Static Multipath Configuration.................................................................................237
19.8 Atmospheric Configuration......................................................................................249
19.9 Satellites Constellation.............................................................................................252
19.10 Signals and Power Configuration per Satellite...................................................... 259
19.11 SBAS Corrections..................................................................................................... 272
19.12 Navigation Message Configuration......................................................................... 281
19.12.1 Simulated Orbit, Orbit Perturbation and Clock Commands.........................................282
19.12.2 Pseudorange Commands........................................................................................... 293
19.12.3 Orbit, Clock, System, Time Convertion and Ionospheric Errors..................................300
19.13 Signal Dynamics....................................................................................................... 351
19.14 Assistance Data Settings......................................................................................... 359
19.15 Data Logging............................................................................................................. 372
19.16 Advanced Mode Commands.................................................................................... 378
19.17 Trigger Settings.........................................................................................................382
19.18 Marker Settings......................................................................................................... 386
19.19 Clock Settings........................................................................................................... 388
Annex.................................................................................................. 390
A User Environment Files.....................................................................390
A.1 Movement or Motion Files........................................................................................390
A.1.1 Waypoint File Format.................................................................................................. 390
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A.1.2 Vector Trajectory File Format......................................................................................391
A.1.3 NMEA Files as Source for Movement Information...................................................... 394
A.1.4 Trajectory Description Files.........................................................................................394
A.1.5 Resampling Principle.................................................................................................. 398
A.1.6 Calculating the Maximum Time Duration of a Movement File.....................................399
A.2 Vehicle Description Files (Used for Smoothening)................................................399
A.3 Antenna Pattern and Body Mask Files....................................................................401
B RINEX Files.........................................................................................404
B.1 RINEX Format Description....................................................................................... 404
B.2 Example of a RINEX File...........................................................................................405
C NMEA Scenarios................................................................................ 407
D QZSS Navigation Message Scheduling........................................... 409
E List of the Supported Predefined Test Scenarios...........................410
F Ionospheric Grid File Format............................................................415
G Channel Budget..................................................................................416
H List of the Provided Predefined Files...............................................418
Glossary: List of Publications with Further or Reference Informa-
tion.......................................................................................................420
List of Commands..............................................................................422
Index....................................................................................................452
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ContentsSatellite Navigation
8User Manual 1178.6379.02 ─ 01
1 Preface
PrefaceSatellite Navigation
About this Manual
1.1 About this Manual
This user manual provides all the information specific to the GNSS options. All general instrument functions and settings common to all applications and operating modes
are described in the main R&S SMW user manual.
The main focus in this manual is on the provided settings and the tasks required to
generate a signal. The following topics are included:
●
Introduction to and getting familiar with the options
●
About the GNSS options
Background information on basic terms and principles in the context of the signal
generation
●
GNSS Configuration and Settings
A concise description of all functions and settings available to configure signal generation with their corresponding remote control command
●
How to Perform Typical Signal Generation Tasks with the GNSS Options
The basic procedure to perform signal generation tasks and step-by-step instructions for more complex tasks or alternative methods
As well as detailed examples to guide you through typical signal generation scenarios and allow you to try out the application immediately
●
Remote Control Commands
Remote commands required to configure and perform signal generation in a
remote environment, sorted by tasks
(Commands required to set up the instrument or to perform common tasks on the
instrument are provided in the main R&S SMW user manual)
Programming examples demonstrate the use of many commands and can usually
be executed directly for test purposes
●
Annex
Reference material such as description of file formats, extensive lists, and tables
●
List of remote commands
Alphabetical list of all remote commands described in the manual
●
Index
Contents and scope
This description assumes R&S SMW equipped with all availabe options. Depending on
your model and the installed options, some of the functions may not be available on
your instrument.
Notes on screenshots
When describing the functions of the product, we use sample screenshots. These
screenshots are meant to illustrate as much as possible of the provided functions and
9User Manual 1178.6379.02 ─ 01
PrefaceSatellite Navigation
Documentation Overview
possible interdependencies between parameters. The shown values may not represent
realistic usage scenarios.
The screenshots usually show a fully equipped product, that is: with all options installed. Thus, some functions shown in the screenshots may not be available in your particular product configuration.
1.2 Documentation Overview
This section provides an overview of the R&S SMW user documentation. Unless specified otherwise, you find the documents on the R&S SMW product page at:
www.rohde-schwarz.com/manual/smw200a
1.2.1 Getting Started Manual
Introduces the R&S SMW 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.
1.2.2 User Manuals and Help
Separate manuals for the base unit and the software options are provided for download:
●
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.
●
Software option manual
Contains the description of the specific functions of an option. Basic information on
operating the R&S SMW is not included.
The contents of the user manuals are available as help in the R&S SMW. The help
offers quick, context-sensitive access to the complete information for the base unit and
the software options.
All user manuals are also available for download or for immediate display on the Internet.
1.2.3 Tutorials
The R&S SMW provides interactive examples and demonstrations on operating the
instrument in form of tutorials. A set of tutorials is available directly on the instrument.
10User Manual 1178.6379.02 ─ 01
PrefaceSatellite Navigation
Documentation Overview
1.2.4 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, https://gloris.rohde-schwarz.com).
1.2.5 Instrument Security Procedures
Deals with security issues when working with the R&S SMW in secure areas. It is available for download on the Internet.
1.2.6 Basic Safety Instructions
Contains safety instructions, operating conditions and further important information.
The printed document is delivered with the instrument.
1.2.7 Data Sheets and Brochures
The data sheet contains the technical specifications of the R&S SMW. It also lists the
options and their order numbers and optional accessories.
The brochure provides an overview of the instrument and deals with the specific characteristics.
See www.rohde-schwarz.com/brochure-datasheet/smw200a
1.2.8 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/smw200a
1.2.9 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/smw200a.
11User Manual 1178.6379.02 ─ 01
Welcome to the GNSS Satellite Navigation OptionsSatellite Navigation
2 Welcome to the GNSS Satellite Navigation
Options
The R&S SMW-K44/-K66/-K94/-K98/-K106/-K107/-K99/-K108/-K120 are firmware
applications that add functionality to generate signals in accordance with GPS, Galileo,
GLONASS, QZSS, COMPASS/BeiDou and SBAS navigation system.
The global navigation satellite system (GNSS) solution for the R&S SMW is suitable for
R&D lab tests or production tests. Supported are all possible scenarios, from simple
setups with individual satellites all the way to flexible scenarios generated in real time.
The realtime scenarios can include up to 36 GPS, Glonass, Galileo, QZSS and BeiDou
satellites.
The GNSS key features are:
●
Support of GPS L1/L2 (C/A and P code) and GPS L2 L2C signals, Glonass L1/L2
C/A-code signals, Galileo E1, BeiDou B1-I/B2-I signals and QZSS L1 C/A signals,
including mixed constellations
●
Configuring the state of a particular signal component individually.
●
Simulation of SBAS satellites and support of the EGNOS/WAAS/MSAS/GAGAN
and QZSS regional systems.
●
Realtime simulation of realistic mixed constellations and unlimited simulation time
●
Flexible scenario generation including moving scenarios, dynamic power control
and atmospheric modeling
●
Configuration of user environments, including multipath, antenna characteristics
and vehicle attitude
●
Navigation and tracking test modes.
●
Simulation of orbit perturbations and pseudorange errors
●
Support of ranging, correction and integrity services for SBAS
●
Configuration suitable for basic receiver testing using signals with zero, constant or
varying Doppler profiles
●
Common configuration of multi-frequency GNSS scenarios
●
Support of assisted GNSS test scenarios, including generation of assistance data
for GPS, Glonass, Galileo and BeiDou
●
Logging of user motion and satellite-related parameters
●
High signal dynamics, simulation of spinning vehicles to support aerospace and
defense applications
This user manual contains a description of the functionality that the application provides, including remote control operation.
All functions not discussed in this manual are the same as in the base unit and are
described in the R&S SMW user manual. The latest version is available at:
www.rohde-schwarz.com/manual/SMW200A
12User Manual 1178.6379.02 ─ 01
Welcome to the GNSS Satellite Navigation OptionsSatellite Navigation
Installation
You can find detailed installation instructions in the delivery of the option or in the
R&S SMW Service Manual.
Scope
2.1 Accessing the GNSS Dialog
To open the dialog with GNSS settings
► In the block diagram of the R&S SMW, select "Baseband > Satellite Navigation".
A dialog box opens that displays the provided general settings.
The signal generation is not started immediately. To start signal generation with the
default settings, select "State > On".
2.2 Scope
Tasks (in manual or remote operation) that are also performed in the base unit in the
same way are not described here.
In particular, it includes:
●
Managing settings and data lists, like storing and loading settings, creating and
accessing data lists, or accessing files in a particular directory.
●
Information on regular trigger, marker and clock signals and filter settings, if appropriate.
●
General instrument configuration, such as checking the system configuration, configuring networks and remote operation
●
Using the common status registers
For a description of such tasks, see the R&S SMW user manual.
13User Manual 1178.6379.02 ─ 01
3 Required Options
R&S SMW base unit equipped with the following options:
●
Option baseband generator (R&S SMW-B10), per signal path
●
Option frequency (R&S SMW-B103/-B203), per signal path
●
At least one of the following options, per signal path:
– GPS (R&S SMW-K44)
(required for the generation of C/A and P signals in the L1 and L2 bands)
– Galileo (R&S SMW-K66)
– GLONASS (R&S SMW-K94)
– BeiDou (R&S SMW-K107)
●
Optional, modernized GPS (R&S SMW-K98), per signal path
(required for the generation of L2C signals in the L2 band)
●
Optional, option SBAS/QZSS (R&S SMW-K106), per signal path
(requires R&S SMW-K44)
●
Optional, extension to 48 channels (R&S SMW-K99), per signal path
●
Optional, real word simulaiton (R&S SMW-K108), per signal path
●
Optional, GNSS advanced (R&S SMW-K120)
Required OptionsSatellite Navigation
For more information, see data sheet.
There is a limitation on the maximum number of satellite signals that can be simulated
simultaneously. For more information, see Chapter G, "Channel Budget",
on page 416.
14User Manual 1178.6379.02 ─ 01
About GNSSSatellite Navigation
GNSS Systems Overview
4 About GNSS
Global navigation satellite system (GNSS) employs the radio signals of several navigation standards, like GPS, Galileo, GLONASS, and BeiDou. For several years, GPS
used to be the only standard available for civilian navigation through its C/A civilian
code. Nowadays, the GNSS signals and systems are undergoing fast development,
some systems are getting modernized and some are new. In the foreseeable future,
several more GNSS satellites utilizing more signals and new frequencies are available.
The GNSS implementation in the R&S SMW enables you to generate the signal of up
to 24 or 48 GNSS satellites, depending on the installed options. Signal generation is
performed in real time and thus not limited to a certain time period.
4.1 GNSS Systems Overview
Brief introduction to the global navigation satellite systems
●
GPS
The Global Positioning System (GPS) consists of several satellites circling the
earth in low orbits. The satellites transmit permanently information that can be used
by the receivers to calculate their current position (ephemeris) and about the orbits
of all satellites (almanac). The 3D position of a receiver on the earth can be determined by carrying out delay measurements of at least four signals emitted by different satellites.
Being transmitted on a single carrier frequency, the signals of the individual satellites can be distinguished by correlation (gold) codes. These ranging codes are
used as spreading code for the navigation message which is transmitted at a rate
of 50 bauds.
●
Galileo
Galileo is the European global navigation satellite system that provides global positioning service under civilian control. It is planed to be inter-operable with GPS and
GLONASS and other global satellite navigation systems.
The fully deployed Galileo system consists of 30 satellites (27 operational and 3
spares). Three independent CDMA signals, named E5, E6 and E1, are permanently transmitted by all Galileo satellites. The E5 signal is further subdivided into
two signals denoted E5a and E5b (see Figure 4-1).
●
GLONASS
Glonass is the Russian global navigation satellite system that uses 24 modernized
Glonass satellites touring the globe. Together with GPS, up to 54 GNSS satellites
are provided, which improves the availability and therefore the navigation performance in high urban areas.
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About GNSSSatellite Navigation
GNSS Systems Overview
Figure 4-1: GNSS frequency bands
●
COMPASS/BeiDou
The fully deployed BeiDou navigation satellite system (BDS) is a Chinese satellite
navigation system. This navigation system is also referred as BeiDou-2 and is
expected in 2020. The BDS is a global satellite navigation system a constellation of
35 satellites to cover the globe. This constellation includes 5 geostationary orbit
satellites (GEO) and 30 non-geostationary satellites; 27 in medium earth orbit
(MEO) and 3 in inclined geosynchronous orbit (IGSO).
The BDS uses frequency allocated in the E1, E2, E5B, and E6 bands.
●
Quasi-Zenith satellite system (QZSS)
The Quasi-Zenith satellite system is a regional space-based positioning system.
The system is expected to be deployed in 2013 and the satellites would be a visible Japan.
In its final deployment stage, the QZSS uses a total number of three regional not
geostationary and highly inclined satellites. The QZSS does not aim to cover the
globe but to increase the availability of GPS in Japan, especially in the larger
towns.
The QZSS uses signals that are similar to the GPS public signals.
●
Assisted GNSS (A-GNSS)
Assisted GNSS (A-GNSS) was introduced to different mobile communication
standards to reduce the time to first fix (TTFF) of a user equipment (UE) containing
a GNSS receiver. This is achieved by transmitting information (assistance data)
mainly about the satellites directly from a base station to the UE.
For example, a standalone GPS receiver needs about 30 to 60 seconds for a first
fix and up to 12.5 minutes to get all information (almanac).
In A-GNSS "UE-based mode", the base station assists the UE by providing the
complete navigation message along with a list of visible satellites and ephemeris
data. In addition to this information, the UE gets the location and the current time at
the base station. That speeds up both acquisition and navigation processes of the
GPS receiver and reduces TTFF to a few seconds.
In A-GNSS "UE assisted mode", the base station is even responsible for the calculation of the UE's exact location. The base station takes over the navigation based
on the raw measurements provided by the UE. Since the acquisition assistance
16User Manual 1178.6379.02 ─ 01
About GNSSSatellite Navigation
GNSS Components Overview
data provided by the base station already serves speeding up the acquisition process, the UE only has to track the code and carrier phase.
4.2 SBAS Overview
Brief introduction to the satellite-based augmentation systems (SBAS)
The satellite-based augmentation system uses geostationary satellites (GEO) to broadcast GNSS coarse integrity and wide area correction data (error estimations), and
ranging signal to augment the GNSS.
The SBAS broadcasts augmentation data in the GPS frequency band L1 (carrier frequency of 1575.42 MHz), uses the BPSK modulation, and the C/A PRN code of GPS.
The SBAS provides data for a maximum of 51 satellites. In the SBAS, the term pseudo
random number (PRN) is used instead of the term space vehicle (SV). There are 90
PRN numbers reserved for SBAS, where the numbering starts at 120.
Several SBAS systems are still in their development phase, like, for example, the
SDCM in Russia Federation, and GAGAN in India.
SBAS systems that are currently in operation argument the US GPS satellite navigation system, so that they are suitable, for example, for civil aviation navigation safety
needs. The following SBAS systems are supported by R&S SMW:
●
EGNOS
EGNOS (European geostationary navigation overlay service) EGNOS is the European SBAS system
●
WAAS
WAAS (wide area augmentation system) is the SBAS system in United States
●
MSAS
MSAS (multi-functional satellite augmentation system ) is the SBAS system working in Japan. It uses the multi-functional transport satellites (MTSAT) and supports
differential GPS.
●
GAGAN
GAGAN (GPS aided geo augmented navigation system) is the SBAS implementation by the Indian government.
4.3 GNSS Components Overview
The GNSS system comprises of three main components: the space segment, the
ground segment and the user segment.
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About GNSSSatellite Navigation
GNSS Components Overview
Figure 4-2: GNSS system components (simplified)
1 = Space segment or satellites
2 = Ground segment or ground stations
3 = User segment or receivers
4 = Ephemeris (broadcasted satellites orbit and clock)
5 = Broadcasted navigation message
Space segment
The space segment consists of the satellites that orbit the earth on their individual
orbits. Satellites broadcast signals at specific frequency in the L band and spread by
predefined codes. For the GPS satellites using L1 frequency band, for instance, these
are the coarse/acquisition (C/A) or the precision (P) codes.
The transmitted signal carries the navigation message, on which each satellite broadcasts its major characteristics, its clock offsets and precise orbit description, where the
latter is called ephemeris. The navigation message contains also satellites status
information, ionospheric and time-related parameters, UTC information and orbit data
with reduced accuracy for all other satellites, commonly referred as almanac.
Ground segment
The ground segment is a network of ground stations whose primary goal is to measure constantly the satellites’ location, altitude and velocity, and the satellites signals.
The ground stations also estimate the influence of the ionosphere. They calculate the
precise orbit (and orbit perturbation) parameters and clock drifts parameters of
each satellite. This corrected highly accurate information is regularly broadcasted back
to the satellites so that their navigation messages can be updated.
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How Are the GNSS Components Simulated?
User segment
Finally, the receiver decodes the navigation message (ephemeris and almanac)
broadcasted by the GNSS satellites, obtains information regarding the satellites orbit,
clock, health etc. and calculates the satellites coordinates. The receiver also measures
the signal propagation time (i.e. the pseudorange) of at least four satellites and estimates its own position.
4.4 How Are the GNSS Components Simulated?
In the real life, the true satellites orbit can differ from the information the satellites
breoadcast about that orbit.
In this implementation, the simulated orbit is the true orbit. Thus, the satellites motion
along their orbits, the clock they use and the current distance to each of them are referred to as simulated orbit, clock and pseudorange. They are set as retrieved from
the constellation data source and can be configured on a per satellite basis.
The navigation message of each of the satellites is per default identical to the simulated one. It is referred to as broadcasted navigation message, since it represents the
broadcasted satellite’s signal, see Figure 4-2. Per default, the broadcasted and the
simulated orbit and clock parameters match. Obviously, if the parameters in any of
those two groups are changed, a deviation between the sets is simulated.
The receiver is the device under test (DUT). In the simulation, the receiver is represented by its position, antenna configuration, environment, etc. The receiver is tested with
the GNSS it would receive in a real-word situation if placed in the specified conditions.
Simulation date, time and location
The R&S SMW generates the signal for any simulation date and time, in the past or in
the future, and at any location, on the earth or in the space, for a static or moving
receiver.
You have full control over the satellites’ constellation, the satellites signals and the navigation message of any of the satellites and can thus perform repeatable measurements with varying complexity.
For details, see:
●
Chapter 6, "Simulation Time", on page 35
●
Chapter 7, "Receiver Type and Position", on page 40
●
Chapter 8, "Satellite's Constellation", on page 51
●
Chapter 9, "Space Vehicle Configuration", on page 61
Real-word scenarios trough environmental effects
You can also simulate various different environmental conditions, like the effect of the
receiver’s antenna characteristic, vehicle movement, vehicle body mask, multipath
propagation, obstacles or the atmosphere.
For details, see Chapter 10, "Real-World Environment", on page 81.
19User Manual 1178.6379.02 ─ 01
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How Are the GNSS Components Simulated?
Ionospheric effects
You can also simulated the effect of the atmospheric (ionospheric and tropospheric)
errors on the positioning accuracy.
For details, see "Tropospheric and ionospheric models" on page 102.
GNSS errors sources
Additionally to the real-word and the ionosphere effects, you can simulate signal errors
by manipulating the navigation messages of the satellites. Signal errors have a direct
impact on the receiver’s positioning accuracy.
You can observe the effect of the following common error sources:
●
Orbit and orbit perturbation errors (ephemeris errors)
●
Satellite clock and time conversion errors
●
Pseudorange errors
For details, see Chapter 12, "Perturbations and Errors Simulation", on page 101.
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Getting StartedSatellite Navigation
Trying Out the GNSS Simulator
5 Getting Started
In its default configuration, this software generates GNSS signal that is sufficient for a
receiver to get a position fix.
The simulated GNSS system depends on the installed options. For instance, if
R&S SMW-K44 is installed, it is GPS C/A signal in the L1 band.
For any of the GNSS systems, the simulation starts on 19.02.2014 at 6 am UTC time
and satellite constellation corresponds to the one seen by a static receiver located in
Munich.
● Trying Out the GNSS Simulator..............................................................................21
● General Settings..................................................................................................... 23
● Simulation Monitor.................................................................................................. 26
5.1 Trying Out the GNSS Simulator
The following simple examples can help you get familiar with the basic functions of the
software:
●
"How to generate a GNSS signal for simple receiver tests (default configuration)"
on page 21
●
"How to configure a hybrid satellite constellation" on page 22
How to generate a GNSS signal for simple receiver tests (default configuration)
1. Select "Baseband > Satellite Navigation > GNSS".
2. Select "General > State > On".
The summary information confirms that a single GNSS system signal is generated.
The used frequency band is indicated, too.
3. To observe current satellite constellation, select "GNSS > Simulation Monitor".
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4. In the block diagram, select "RF > On".
Getting StartedSatellite Navigation
Trying Out the GNSS Simulator
The signal generation starts.
The frequency and level of the generated RF signal are configured automatically.
Further settings are not required.
For description of the related settings, see:
● Chapter 5.2, "General Settings", on page 23
● Chapter 5.3, "Simulation Monitor", on page 26
How to configure a hybrid satellite constellation
1. Select "Baseband > Satellite Navigation > GNSS".
2. Select "Simulation Configuration > Systems&Signals"
3. Select the frequency band, e.g. set "L1 > On".
4. Enable the global, regional and augmentation GNSS systems to be simulated, e.g.
"GPS > On", "Galileo > On", "GLONASS > On".
5. Define the signals per GNSS system, e.g. "GPS > C/A > On", "GPS > P > Off".
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General Settings
6. To observe current satellite constellation, select "GNSS > Simulation Monitor".
7. To reconfigure the satellites constellation, select "Simulation Monitor > Config".
8. In the block diagram, select "RF > On".
The signal generation starts.
The frequency and level of the generated RF signal are configured automatically.
Further settings are not required.
For description of the related settings, see:
● Chapter 5.2, "General Settings", on page 23
● Chapter 5.3, "Simulation Monitor", on page 26
● Chapter 8, "Satellite's Constellation", on page 51
5.2 General Settings
Access:
► Select "Baseband > Satellite Navigation > GNSS".
This dialog comprises the standard general settings.
The remote commands required to define these settings are described in Chap-
ter 19.2, "General Settings", on page 206.
Settings:
State..............................................................................................................................24
Set to Default................................................................................................................ 24
Save/Recall Scenario....................................................................................................24
Predefined Scenario......................................................................................................24
Scenario........................................................................................................................25
Test Mode..................................................................................................................... 25
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General Settings
Simulation Configuration...............................................................................................25
Monitor.......................................................................................................................... 26
Data Generation............................................................................................................26
State
Activates the standard and deactivates all the other digital standards and digital modulation modes in the same path.
Remote command:
[:SOURce<hw>]:BB:GNSS:STATe on page 208
Set to Default
Calls the default settings. The values of the main parameters are listed in the following
table.
Parameter Value
State Not affected by "Set to default"
Scenario None
Test Mode Navigation
Simulation Configuration L1/GPS only
Logging Off
Remote command:
[:SOURce<hw>]:BB:GNSS:PRESet on page 207
Save/Recall Scenario
Accesses the "Save/Recall" dialog, that is the standard instrument function for saving
and recalling the complete dialog-related settings in a file. The provided navigation
possibilities in the dialog are self-explanatory.
The filename and the directory, in which the settings are stored, are user-definable; the
file extension is however predefined.
See also, chapter "File and Data Management" in the R&S SMW user manual.
Remote command:
[:SOURce<hw>]:BB:GNSS:SETTing:CATalog? on page 209
[:SOURce<hw>]:BB:GNSS:SETTing:STORe on page 209
[:SOURce<hw>]:BB:GNSS:SETTing:LOAD on page 209
[:SOURce<hw>]:BB:GNSS:SETTing:DELete on page 210
Predefined Scenario
Accesses the standard "File Select" dialog and allows you to select a predefined scenario.
The available test scenarios depend on the installed SW options.
Once a scenario is selected, all parameters (simulated position, satellite configuration,
navigation data, etc.) are configured automatically. The sceanrio name is indicated,
see Scenario.
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Remote command:
[:SOURce<hw>]:BB:GNSS:SETTing:CATalog:PREDefined? on page 210
[:SOURce<hw>]:BB:GNSS:SETTing:LOAD:PREDefined on page 210
Scenario
Indicates one of the following:
●
None: preset (default) configuration, see Set to Default.
●
Scenario name: if predefined scenario is selected, see Predefined Scenario.
●
Filename: if saved settings configuration is loaded, see Save/Recall Scenario.
●
"User-defined" indicates that at least one parameter is changed after a configuration or predefined scenario is loaded.
Remote command:
[:SOURce<hw>]:BB:GNSS:SCENario? on page 208
Test Mode
Set this parameter to match the operation mode in that the DUT works.
Irrespectively of the selected mode, initial satellites constellations are defined by the
predefined or imported constellation data. The number of active satellites with their initial position and messages are retrieved from the constellation data, too. You can edit
the satellite constellation and signals in both modes.
Switching from one test mode to the other presets all satellites parameters to their
default values.
The modes differ in terms of signal content and scenario complexity:
"Navigation"
The satellite signals are configured to correspond to the signal at a
particular location ("Receiver > Location").
The generated signal corresponds to a realistic scenario. The DUT
can achieve position fix, since the satellite constellation comprises of
at least three satellites. The signal is suitable for signal acquisition
and TTFF tests.
"Tracking"
Remote command:
[:SOURce<hw>]:BB:GNSS:TMODe on page 208
Generated is signal without positioning data. Receiver configuration is
not required.
Navigation and acquiring of position fix is not possible. The signal is,
however, sufficient to test the ability of the DUT to find the channel
and to decode the signal. It is also sufficient for sensitivity testing.
Use this mode also if high signal dynamics are required, for example
for the simulation of spinning vehicles and precision code (P code)
such as in some aerospace and defense applications.
For more information, see Chapter 11, "Tracking Mode",
on page 96.
Simulation Configuration
Access the "Simulation Configuration" dialog for defining the active navigation system,
used bands and configure the satellites.
A summary of the current configuration is displayed.
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Simulation Monitor
See:
●
Chapter 8.1, "Systems and Signals Settings", on page 52
●
Chapter 6.1, "Time Configuration Settings", on page 35
●
Chapter 7.1, "Receiver Type", on page 40
●
Chapter 8.2, "Satellites Settings", on page 54
●
Chapter 12.2, "Atmospheric Effects and Ionospheric Errors Settings", on page 106
Monitor
Access the "Simulation Monitor" dialog for real-time display of the major parameters,
like current satellite constellation with SV states and position, receiver position or
movement trajectory, or received satellite power.
See Chapter 5.3, "Simulation Monitor", on page 26.
Data Generation
Access the "Data Generation" dialog for enabling and configuring of data logging,
assistance data generation and generating files by converting .
See:
●
Chapter 15, "Data Logging", on page 171
●
Chapter 16, "Assistance Data Generation", on page 180
5.3 Simulation Monitor
The simulation monitor visualizes the real-word situation of disappearance and reappearance of satellites in real time. Additionally, the simulation monitor is also a
dynamic display of several parameters like HDOP, PDOP, receiver's location, elapsed
time and the trajectory of a moving receiver.
Access:
1. Select "GNSS > General > Simulation Monitor".
Or alternatively:
a) Select "GNSS > General > Simulation Configuration > Monitor".
b) Select "GNSS > General > Simulation Configuration > Receiver/Satellites/
Atmosphere > Monitor".
The dialog displays the view that fits best to the settings in the origin dialog.
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Simulation Monitor
2. To access the related configurations settings or return back to the origin, select
"Simulation Configuration > Config...".
The "Simulation Monitor" is a dynamic display that provides real-time information
on:
● Current satellite's constellation
● Receiver position
● Current simulation time
● Power levels of the active satellites
● HDOP, PDOP.
In the following, the different views are explained in detail. Related remote control commands (SCPIs) are listed, too.
Receiver > Word Map
The "Word Map" indicates the receiver location on the word map.
Satellites > Sky View
The "Sky View" displays the current position and state (active or inactive) of the satellites in the current satellites constellation. In this display, you can, for example, observe
the situation of disappearance and reappearance of satellites.
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Simulation Monitor
Figure 5-1: Simulation Monitor: Example of a hybrid satellite's constellation with obscured satellites
in a moving scenario (car moving in through a city block)
For instruments equipped with option R&S SMW-K108, the "Sky View" indicates also
the obscured satellites, the satellites with echoes, etc. For example, the satellites
which signal is not visible from the current receivers position because there is an
obstacle between the receiver and the satellite, are displayed in gray color.
Receiver > Map View
The "Map View" display the trajectory of moving receiver or the position of a static one.
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Rx = Receiver position
If you analyze the generated GNSS signal with a GNSS receiver software, you can
notice a slight difference in the receiver position. The receiver position displayed on the
"Map View" and the position displayed on the receiver software can deviate at the
beginning of a simulation. This accuracy of the "Map View" display is progressively
increasing with the time elapsed and after the first satellite handover the deviation
completely disappears.
Receiver > Vehicle Dynamics
The "Vehicle Dynamics" displays a compass showing the geographic direction of a
moving receiver, typically an airplane. It also displays an attitude indicator showing the
orientation of this airplane relative to earth's horizon.
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Simulation Monitor
The displayed attitude indicator is known from the flight simulators. The yellow sign in
the middle represents the airplane with its nose and wings. The brown part of the display is the earth, whereas the sky is displayed in blue; the line between the two parts is
the horizon.
The "Attitude View" is changes updated in real time:
●
If the yellow circle, i.e. the nose of the airplane, is on the blue background, then the
airplane is nose up.
●
If a spinning and roll is enabled, the attitude indicator also visualizes pitch and roll
(i.e. bank or side-to-side tilt).
Satellites > Power View
The "Power View" view displays the current power levels of the signals of the active
satellites and their echoes.
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