Continuous Improvement with Spirent

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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 8.00 (including service releases) – June 2022 (by Mia Swain & Chris Yapp)

New ICDs supported

Galileo OS SIS ICD V2.0

The new issue of the OS SIS ICD introduces major updates for all Galileo Open Service users.

3 new features are introduced to the I/NAV message transmitted on the Galileo E1-B signal component:

  • Reduced Clock and Ephemeris Data (RedCED);

  • Reed-Solomon Outer Forward Error Correction Data (FEC2); and

  • Secondary Synchronization Pattern (SSP).

These new features represent a major evolution of the Galileo Open Service signals, which will provide all users with a more robust and faster retrieval of the Clock and Ephemeris Data, particularly for users in challenging environments, while at the same time allowing for a faster reconstruction of the Galileo System Time (GST).

As part of our extensive support entitlement, users will gain access to this updated ICD with the latest software update (PosApp V8.00 GAL FOC 2.0).

New features

New Software User Interface

With the release of v8.00, we have updated the look and feel of our GNSS simulation software. As a customer who has previously used version 7 of SimGEN, SimREPLAY+ and SimTEST, or Single Channel Utility, you will notice some changes to the way the user interface looks and works.

The software has been given a fresh new look – to better align with Windows 10’s look and feel, and with other apps in the Spirent product suite.

Continuous Improvement1

Scenario Play Controls

The controls for starting, stopping, rewinding and engaging turbo mode have been simplified and moved. They can now be found in the top-right corner of the app.

The stop button has been removed and merged with the ‘play’ button.

Continuous Improvement2


The buttons are larger, with clear text labels underneath. They work in the same way as before, showing and hiding the various windows below.

Continuous Improvement3

Scenario Tree

The scenario’s attributes and settings – we call these the ‘scenario tree’ – have been simplified. The tree has been tidied, and the buttons below have been simplified, made more concise and clearly labelled.

Continuous Improvement4

Ground Track

The ground track shows where the scenario’s simulated vehicles and satellites are displayed.

We’ve made it easier to tell the difference between land and sea, easier to determine where your vehicles are, and easier to distinguish where satellites are located in the sky.

Green now signifies visible satellites, blue signifies not visible, and red signifies satellites that are not simulated as part of your license.

Continuous Improvement5

Default Layout

We’ve optimised the size and layout of the information panels to better match the Spirent c50 and Full HD 1080 x 1920 displays, in the default layout configuration.

This gives you more room for your power level and received signals panels, while also fixing the date/time and position details panels for consistency and clarity.

Continuous Improvement6

Antenna configuration window

V8.00 introduces a set of new features that focus on customer experience. One of these features is the antenna configuration window, a tool that has been designed to accurately recreate and represent the position and orientation of the antennas with respect to the vehicle in the scenario.

This tool allows users to prepare their antenna set-up before the simulation starts. It helps to visualise the active configuration in a dynamic 3D plot as one edits parameters such as antenna offsets, heading, elevation and bank angles. Whether the user is running a single or multi-antenna scenario, the antenna configuration window enables them to create, edit or delete their vehicle antennas as well as easily share settings across SimGEN scenarios.

Continuous Improvement7

For the most advanced use-cases, a CRPA definition tool has been also incorporated. In 2 steps, users can now create antenna arrays and uniformly space the individual elements based on half wavelengths or precise distances. This capability comes with the associated 3D plot that enables the visualisation of the relative distances between the different antenna elements.

Continuous Improvement8

Once a CRPA antenna is created, SimGEN will holistically identify the individual elements as part of a CRPA entity and will always reflect it within a single instance of the software. This allows users to modify in-run parameters such as power levels for the whole CRPA antenna using the sliders within SimGEN.

Spoofing Capability

Release v8.00 Spoofing introduces the embedded spoofing feature (licensable), Spirent’s new all-in-one spoofing solution.

The new spoofing feature comprises powerful built-in and user configurable capabilities to generate spoofing scenarios. It covers most spoofing attacks such as trajectory spoofing, navigation data spoofing and meaconing attacks, and works on all GNSS constellations and frequencies. For increased realism, the spoofing signals are now transmitted from ground-based transmitters.

Fully embedded into SimGEN, the user can easily define, amongst other parameters, the number of spoofer transmitters and their location (absolute or vehicle relative, static or moving), the spoofer power levels, the false vehicle position (spoofed position) and the spoofing signal content, including navigation data and errors. The resulting spoofer RF signal will be automatically calculated based on user scenario settings, with the correct spoofer signal arrival angle and spoofer signal content.

The new feature is available on GSS9000, GSS7000 SimGEN and SimREPLAY+.

Continuous Improvement9


V8.00 introduces significant updates for SimSENSOR and SimINERTIAL (via new version v5.05). The inertial error model (shared by the two inertial sensor simulation solutions) has been enhanced with the addition of new embedded vibration and temperature models. SimINERTIAL and SimSENSOR users will now be able to test their inertial sensors and INS against the effects of these environmental errors.

The vibration-induced errors affecting accelerometers are simulated via a vibration model based on MIL-STD-810-H. The model includes the pre-defined vibration profiles defined in the standard (e.g. aircraft, helicopter, shipboard), as well as user-defined ASD vs. frequency vibration profiles. Multiple vibration profiles can be applied at different time in a given scenario.

The temperature model is based on two industry-recognized research papers and simulates the effects of temperature on MEMS-based accelerometers and gyroscopes. The user can define the scenario temperature profile and set the values of critical temperature parameters.

SimSENSOR will also benefit from new embedded and pre-defined error models, for Consumer/Automotive, Industrial, Tactical and Navigation performance grades of IMUs, for an easy and more realistic simulation of common IMU models.

Continuous Improvement10

Improved remote control

V8.00 adds further sophistication to SimGEN’s remote-working functionality. From v8.00, you can remotely restart the SimGEN engine via a command-line interface. Engine control has long been a facet of the Host Controller Utility, which also includes the ability restart the firmware and configure network ports for remote control of the software. This is in addition to recent improvements made to the utility that enable both the GSS9000 and its Host Controller to be turned on, rebooted, and powered off from a remote computer.

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:




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.