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Continuous Improvement with Spirent


Spirent’s SimGEN is built on decades of experience, delivering the power, flexibility, and intuitive ease-of-use needed to develop the next generation of location-aware systems. To ensure our customers stay ahead of the industry, Spirent dedicates a large team to improving the performance and broadening the performance of our flagship simulation control platform.

If you’d like to find out more about renewing your support agreement, and the great value that it provides, get in touch.

NOTE: SimGEN™, SimREPLAYplus™, SimTEST™, and Single Channel Utility are built on Spirent’s SimGEN architecture. References to updates and improvements will refer to SimGEN unless stated otherwise.

Version 7.04 (including service releases) – December 2021 (by Mia Swain & Chris Yapp)

New ICDs supported


GLONASS CDMA signal system V1.0

  • Spirent has led the way with the first commercially-available GLO CDMA simulation solution. For more information on GLONASS CDMA signals and Spirent’s implementation, please visit our blog.

Galileo High Accuracy Service testing ICD V1.2

  • Galileo HAS will provide free-of-charge high-accuracy Precise Point Positioning corrections through the Galileo E6-B signal, with accuracy under two decimeters, offering real-time improved user positioning performance.

  • Working with GMV, Spirent has developed the industry’s first commercially available simulation test solution for the Galileo HAS, via a beta interface implementation based on HAS ICD version 1.2.

  • As part of our extensive support entitlement, all existing Galileo E6 customers will gain access to this functionality with the latest software update (V7.04 SR01 HAS).

New features


Software tool SimOSNMA is designed to work with Spirent’s market leading GNSS simulation platforms to test Galileo Open Service Navigation Message Authentication (OSNMA ICD V1.1) signal conformance, which will bring new levels of robustness for both civilian and commercial GNSS uses.

SimOSNMA has been developed together with Qascom, a leader in GNSS resilience and a significant contributor to the development of Galileo OSNMA. For more information, please refer to Spirent’s press release, or contact your local Spirent representative.

Premium enhancements to the GSS9000 Series

1. Rolling RINEX (also available on GSS7000 with SimGEN Software)

As spoofing techniques become more sophisticated in the real-world, Spirent remains committed to bringing the most advanced anti-spoofing test techniques to the lab.

For this purpose, from V7.04 release, all Spirent GNSS constellation simulators are capable of updating ephemeris data on user demand based on existing RINEX files. This feature permits a close alignment between the simulator and the live-sky signals during the scenario run.

2. Enhanced embedded multipath

Achieving greater realism is a key aspect and a common theme for most of today’s simulation test tools. In the GNSS domain, multipath plays an important role in realism due both to the low power of the signals received, and the diversity of the scenarios where receivers operate.

In the V7.04 release, new functionality is added to the GSS9000 Series embedded multipath feature. Users can now control the power levels and code delays of each multipath signal in real-time, enabling the creation of more complex and dynamic scenarios for greater representation of the real world.


3. 32-channel interference channel banks

The V7.04 release unlocks another new feature of GSS9000 Series simulator. The number of simultaneously generated GNSS and interference signals is expanded to 32 per channel bank, enabling a 2RF interference-capable GSS9000 Series to simulate up to 160 GNSS signals (RF1) and 160 interference signals (RF2). This was previously limited to 160 GNSS signals and 80 interference channels.

Increased antenna power level control

V7.04 adds the ability to apply power level changes to all vehicle antennas in a single action. This feature is applicable to scenarios with more than one antenna defined, whether the antennas share a vehicle, or are spread across multiple vehicles. With a multi-antenna scenario loaded, the “All antennas” option can be accessed from the Power Adjustment dialog. For scenarios containing multiple vehicles, the “All vehicles” option is also made available.

Enabling the “All antennas” feature ensures any power level changes are applied to all the vehicle’s antennas configured for the signal being adjusted. By selecting “All vehicles” as well, the same changes can be cascaded to every antenna, irrespective of which vehicle they are assigned to:


GSS9000 Simulator and Host Controller remote power on / off / reboot

V7.04 adds the capability to remotely control power to the simulator and its C50r Host Controller. Functionality to power on, reboot and shutdown both the GSS9000 Simulator and C50r Host Controller is provided via the Host Controller Utility when used with a supported IP power switch. This enables essential maintenance and power conservation to be conducted remotely.

To further enhance the remote-working experience, the Host Controller Utility is now present in the Remote PC instance of PosApp. To install, select the SimREMOTE option during the installation process on your Remote PC.

Version 7.03 – July 2021 (by Mia Swain & Chris Yapp)

New ICDs supported

QZSS L6 : IS-QZSS-L6-003
RTCM V3.3 : RTCM 10403.3

New features

Premium enhancements to GSS9000 simulator

2kHz simulation update rate on GSS9000 GNSS simulator (on 3rd Gen GSS9000 only)

There is now a licensable option on GSS9000 simulator to achieve a maximum software and hardware update rate of 2 kHz (maximum scenario duration: 24 hours on up to 80 channels. For more details, please refer to the GSS9000 specification datasheet). This improves the accuracy of simulated trajectory for fast moving vehicles and operations such as space missions, hypersonic vehicles and drone testing use cases.

The faster update rate also improves latency for hardware-in-the-loop (HIL) testing, enabling trajectory and motion data from third-party hardware and software systems to be ingested and processed in real time at faster rates.

Extended maximum scenario duration to 65 days

V7.03 extends the available scenario duration to 65 days on GSS9000 and GSS7000 simulators with SimGEN and SimREPLAYplus software platforms (limitation applies on GSS9000 when SIR exceeds 100Hz. For more details, please refer to the GSS9000 specification datasheet).

This will benefit some test cases such as space missions where long-term simulation is needed. Extended scenario duration enables test runs using the same initial conditions – with reduced user inputs – for the duration of the simulation, delivering uninterrupted high-performance testing for longer.

Enhanced Embedded Interference (GTx) Capabilities

In v7.03 release, Spirent has improved support for interference testing on wide spectrum signals, increased bandwidth resolution and repetition rates, and added variable bandwidth control on additive white Gaussian noise (AWGN).

For more details, please refer to the specification datasheets of the GSS9000 and GSS7000 simulators.

New Python example script added to PosApp installer

This new script is a quick setup guideline to help users better compose TCP string commands using Python.

The "posapp_simremote_control_example.py" script exemplifies how SimREMOTE control of PosApp can be achieved via Python. The script contains a series of generic functions to support communication with PosApp over TCP/IP (socket operations).

An example remote control session is included within the script and will take effect once the script is executed. The script requires Python v3 or later to be installed on the remote client end which controls PosApp. Operation is not limited to the commands specified within the example script; any SimREMOTE command defined in the SimREMOTE User Manual can be used to control PosApp by adapting the example Python script to include the required command.

Please contact Spirent support service for more detailed advice on customising the script for your test needs.

Multipath control added to Maximum Simulated Satellites limit

PosApp v7.03 introduces the ability to control whether multipath signals are included the in the limits set by altering the Maximum Simulated Satellites parameter. This control is provided with a remote command and is applicable to SimGEN, SimREPLAYplus, SimTEST and Single Channel Utility.

Maximum Simulated Satellites - accessed from Options > General Options
Default: 999
Used to limit the maximum number of satellites PosApp simulates. Note, if one satellite per constellation is required, see "Single Channel Mode" on PosApp’s "File" menu.

Exclude MP signals - accessed from Options > General Options
Default: Disabled; multipath signals are included in the limit
When enabled, you can control the maximum number of simulated satellites without impacting the number of channels used to produce multipath signals.

Spirent offers several multipath control methods, which allow you to configure the type, offset and quantity of echoed signals, as well as which satellite they originate from.

The Exclude MP signals feature is accompanied by a remote command:
USER_SETTINGS_UPDATE, { "exclude_mp_signals": "<state>" }
Where <state> is either "true" (enabled) or "false" (disabled)

‘Signal Off’ option added to Single Channel Utility’s Power Adjustment dialog

Default: Disabled; all signals are set “On
When selected under the constellation slider, all signals in that constellation are turned “Off”, disabling all power level sliders in that constellation. All signal levels for that constellation display as ‘Off’ in the Power Levels Graph.

When selected under the frequency slider, all signals in that frequency are turned “Off”, disabling all power level sliders in that frequency. All signal levels for that frequency display as ‘Off’ in the Power Levels Graph.

"Import" function added to Source File dialogs

Located alongside the existing “Browse” function present in various SimGEN and SimREPLAYplus dialogs, an “Import” option has been added to v7.03. The text "Linked" is displayed below the file’s path to show that PosApp is using the chosen file in the scenario.
BeiDou Signal Sources File > Rolling Grid File examples are shown below.

Browsing to the file you want to use keeps the chosen file in its original location; PosApp records its path and filename in the scenario. This solution is suitable if the scenario is only to be used on one simulator system, or if multiple scenarios are to use the same file:

Importing the file you want to use makes a copy of the chosen file in your scenario’s folder. This solution is useful if you move scenarios between systems, or share them with partners (including Spirent):

Data Streaming now supports multiple concurrent versions of EthernetShare.h

EthernetShare.h is a C++ header file supplied with PosApp, which, along with your own C/C++ code, allows you to implement data streaming clients. EthernetShare.h enables PosApp to interface with supported third-party software.

The EthernetShare.h file is subject to configuration control. The file has undergone several updates since its first use with PosApp; at the time of writing the file is at version 27. A record of the changes at each release is contained within the EthernetShare.h file. The file's version can be determined my reading the "static const unsigned short" "version_major" and "version_minor" values.

From PosApp v7.03, PosApp can support multiple concurrent versions of EthernetShare.h file. The EthernetShare.h version is chosen from the Data Streaming Definition > General dialog.

To choose the required version, ascertain the "Built with EthernetShare.h version" from the Data Streaming Definition > General dialog.
If 26 or less, choose the same version
- If 27 or more, choose the version number that matches the version shown in Data Streaming Message Logger

Apply transmission delay to GPS L1 C/A Navigation message

PosApp v7.03 adds the ability to delay the transmission of the GPS L1 C/A navigation message by up to 6 seconds. The delay is applied to the time of action and is specific to the chosen satellite(s) within the GPS constellation to which navigation data modifications are defined.

The Time Delay is configured using the GPS Signal Sources file’s Navigation Data Modification dialog for Legacy NAV Data Mod:

Version 7.02 – March 2021

New ICDs supported
BeiDou B2b signal and Precise Point Positioning service

New features

Galileo E6 signals’ PRN code sequence is now supported on the GSS7000

There are two dedicated signals transmitted on Galileo E6 band (1260-1300 MHz): E6-B and E6-C. Both channels allow the encryption of the information at signal level. Spirent’s industry leading GSS9000 simulator continues to provide support for encrypted signals to authorised users, with the GSS7000 now adding the limited capability to support the PRN code sequence without the navigation message.

March PNT update image1

Spectra of Galileo Signals in E6 (source: https://gssc.esa.int/navipedia/index.php/Galileo_Signal_Plan)

Simulation of multiple RTCM reference stations

A new feature introduced in V7.02 enables the simulation of up to 10 RTCM reference stations. Parameters of each reference station, such as location, RTCM version and message type, can be freely edited by the users. NTRIP protocol is supported in SimGEN, meaning all reference stations can be configured as NTRIP Servers streaming correction messages to a designated NTRIP Caster for testing.

This new feature will allow the user to test both rover and Caster’s ability to select/connect to the most suitable reference station and apply its corrections as the rover moves along its trajectory. It could also enable the simulation of a Multi-Base Station (MBS) Real Time Kinematic (RTK) system to help verify the accuracy of Virtual Reference Stations.

Control GPS L1/L2/L5 power levels independently

Applicable to all control software levels, for all supported simulators, SimGEN v7.02 adds a greater degree of power level control while the scenario is running. In addition to altering power levels by Constellation or Channel, you can now change the power level of each frequency within the constellation independently. For instance, the power level for GPS L1 signals can be controlled separately to that applied to GPS L2 or GPS L5 signals.

This is accomplished using either the Power Adjustment window or remote command (SAT_FREQ_POW_OFFSET).

March PNT update image2

March PNT update image3

Simulation of more BeiDou SVs

By the beginning of 2020, there were over 50 BeiDou satellites in space. To enable more realistic simulation of the BeiDou constellation, the default number of BeiDou SVs has been increased to 30. With the ‘extended constellation’ function, SimGEN is capable of simulating 33 additional SVs as specified in BDS ICDs. A total of 63 SVs are now available with the latest software release.

Single Channel Utility Emulator commands

IEEE commands are used by the Single Channel Utility’s (SCU) Emulator to send legacy direct commands to control the GSS7000 simulator system. SimGEN v7.02’s SCU User Manual includes the complete list of Emulator commands, including for:

  • Scenario commands – simulator info, scenario start/stop controls

  • Signal power commands – signal power level controls

  • Signal control commands – constellation, nav data, velocity profile controls

  • Pseudorange commands – initial pseudorange controls

  • Hardware and calibration commands – BITE, reference frequency, error status

The User Manual also provides a comprehensive list of equivalent SCU GSS6300 emulator remote commands.

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Mia Swain
Mia Swain

Mia Swain is a Product Manager working on simulator products and PNT solutions within the Spirent Positioning Technology business unit. She has an academic background in Physics and worked in R&D, applications engineering and then product management. Mia Swain’s current focus is managing the commercial status and development lifecycle of Spirent’s commercial grade GNSS simulator and its software platform, ensuring that the products maximize their commercial value and next generation products meets the needs of the market.