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 7.00 – August 2020

Important notice

Following the end of support for Windows 7, SimGEN version 7.00 has been tested under the Windows 10 environment only.

New ICDs supported



NaVIC (IRNSS) L5 - now supported on Single Channel Utility

New features

We are pleased to announce that a graphical user interface (GUI) for Single Channel Utility (SCU) is now available to supported customers with the release of PosApp V7.00.

Spirent’s PosApp software supports the generation of a single channel output for each licenced signal. The Single Channel Utility allows individual control of several parameters including: a satellite’s carrier frequency, power level, velocity profile and PRN, secondary code and navigation data. Single Channel Utility GUI provides a user interface to all current SCU remote commands on GSS7000 and GSS9000 simulators, and any PosApp product (SimGEN, SimREPLAYplus, SimTEST) can operate in single channel mode.


All PosApp products (SimGEN, SimREPLAYplus, SimTEST) can be switched to operate in single channel mode via "Options" -> "Control Options" -> "Single channel mode":


The new 2-Vehicle 1-RF trajectory spoofing licensable feature allows 2 vehicles to be defined with independent trajectories at the same RF output. To simulate a trajectory spoofing attack, 2 sets of GNSS signals are generated at a single output to simulate 2 different vehicle trajectories (static or dynamic). These two trajectories could be aligned originally with one set of GNSS signals then altered to simulate one trajectory gradually diverted from the ‘truth’ trajectory. The receiver can be spoofed to follow the altered signal set, diverging from the truth data according to the user-controlled parameters.

Applicable to GPS, GLONASS, Galileo and BeiDou constellations (plus their respective ground-transmitter interference constellations), the multi-copy constellation feature for receiver anti-spoofing tests enables the generation of up to 10 copies of any licenced constellation – each with full manipulation of parameters via the signal sources file (1 source file for each copy).

By using the multi-copy constellation feature, users can:

  • Have more than one satellite constellation per GNSS type

  • Choose whether the satellite constellation uses traditional orbits or has fixed, ground-based positions

  • Treat the first constellation for each GNSS type as ‘truth’

  • Modify constellation parameters based on intended signal attack simulation

Signal Flexibility allows the user to select an existing GNSS signal and replace its standard (ICD-defined) content with user-defined values. With this feature, an open API and flexible system architecture turns the GSS9000 into an arbitrary waveform generator (AWG).

Fundamentally, this feature allows built-in user-configurable setup and control

  • Experimental and pre-operational SIS ICD PRN codes

  • Navigation data content and rate

  • Chipping rate

  • Edge-shaping

  • Modulation types

New support of ‘rolling’ SP3 files and navigation data generation by curve-fit adds realism to GNSS satellite orbit simulation. To enable this function, go to “Options” -> “General options” -> “generate nav data by curve-fit”.

SimGEN will interpolate between records and, if required, extrapolate beyond the ends of the files. Navigation data is generated using a curve-fitting process similar to that used by GNSS Control Segments, meaning users will see ephemeris and clock errors which are highly representative of those observed under live-sky conditions. This is PosApp’s most realistic simulation to date, allowing users to:

  • See the increased accuracy of modernised ephemerides

  • Observe the degradation of accuracy that occurs outside of an ephemeris’ validity period

  • See the different precision of different almanac messages

  • Test receiver performance across discontinuities at ephemeris cutovers

  • Quickly and simply exercise all available orbit and clock parameters in each navigation message

The maximum number of GTx (Ground Transmitter) channels permissible on the GSS9000 has been increased from 16 to 64 simultaneous embedded interference channels from a single constellation. The 64-channel maximum can consist of 64 channels of one signal type or up to 32 channels of two GTx signals and so on. For example, “64 GTx_GPS_L1” or “32 GTx_GPS_L1 and 32 GTx_GPS_L2”.


The GTx dialogue menus have been improved to include a field to specify the “max transmitters” and the fixed attenuator value for each simulated GTx signal. The increase enables larger or denser jamming fields to be produced. The position, motion, power, and signal type of each Ground Transmitter can be independently controlled.

As of V7.00, the External Power Gain range has been increased to -30dB to +130dB. Accessible as a parameter on the General Options menu, it is used to change the reference level seen in the Power Levels Graph to display the actual power level experienced by the device under test. It is intended to allow the user to show the effect of cables, amplifiers and attenuators between the simulator and the device.

Version 6.07 – February 2020

Windows 7 support ends

Further to the announcements made in 2018 (NWS10171) and 2019 (NWS10196), support for Windows 7 by Spirent's positioning and navigation products has now ended. Consult NWS10242 for the latest information and details on what to do if you are affected.

Version v6.07 is the final SimGEN release Spirent built for use with Windows 7. Subsequent releases will not be tested or qualified for use with the retired operating system. All new simulator purchases are shipped with Windows 10.

Visit FAQ19022 for a list of the first Windows 10 compatible software versions, and the last release tested with Windows 7 for the following positioning products:


New ICDs supported

IS-QZSS-L6 Nov. 2018 version

BDS-SIS-ICD-B3I V3.0 Feb. 2019 (for the change notes, please refer to article NWS10240 on Spirent Customer Service Center)

BDGIM Ionospheric Model for BeiDou Phase 3 signals

ISRO-IRNSS-ICD-MSG-INCOIS-1.0 Mar. 2019 version

New features

GALILEO E5 observation data can now be output separately as E5a/E5b in a RINEX output file, rather than as 1 signal. This feature will help customers in, for example, RTK simulation tests where GALILEO E1 and E5a signals are used together.

V6.07 also introduces the capability to exclude or include logged data for all satellites, even when they are not simulated. The number of channels displayed is only limited by the simulator’s specification and the number of channels purchased.

SimTEST has its own dedicated scenario folder - in alignment with SimGEN and SimREPLAYplus. This change is in response to customer feedback and is intended to make locating the example SimTEST scenarios easier.

If you have an idea that could improve our software, please bring it to our attention by contacting Spirent Global Services via support@spirent.com, or by raising a Service Request from the “Cases” tab on the Customer Service Centre (CSC) website: support.spirent.com.  

It is now possible to simulate NavIC (IRNSS) AutoNav with Spirent software. AutoNav is a feature of IRNSS / NavIC constellation that allows satellites to transmit differential correction (DC) data within message type 14 to other satellites in the constellation. This DC data provides corrections that can be applied to both clock and ephemeris data before the satellite broadcasts its own NavData.

SimGEN simulates this by allowing the user to set a satellite to AutoNav mode at a custom time during the scenario run in the “Status control” menu. When this point is reached in the scenario, the satellite will enter AutoNav mode and will begin to transmit the DC parameters set in the “Diff. correction table” menu.

With the integration of Open Street Maps, SimROUTE is now available to customers in China and Korea who have limited access to the Google Maps server. SimROUTE is an online tool that generates route-matched trajectory data from online map services to create road-matched trajectory data, and is available free of charge to Spirent customers with a valid Spirent Support Service contract.

To view the full V6.07 Release Notes, please visit the Knowledge Base.

Version 6.06 – December 2019

New ICDs supported

IS-GPS-200K May 2019 version

IS-GPS-705F May 2019 version

IS-GPS-800F May 2019 version

RTCM Standard 10403.2

New features

Spirent now supports Earth Orientation Parameters from ITRF 2014. The ITRF2014 solution replaces the ITRF2008 solution that was published by the IERS on 31 May 2010. ITRF2014 consists of sets of station positions and velocities with their variance/covariance matrices. It has been computed using solutions from four difference space geodetic techniques: VLBI (Very Long Baseline Interferometry), SLR (Satellite Laser Ranging), DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite), and GPS.

SimGEN now allows time synchronization between scenarios and real-world (host PC), for some specific timing tests. For example, simulators are used to change GPS locations to move telecom devices into different infrastructures (i.e. LTE cores from different vendors). It can be beneficial to simulate with current time/PC time so that data collected from modem logs are easier to analyse and compare.

Scenarios containing “Rectangular Racetrack” motion can be loaded in SimREPLAYplus, and the following parameters edited:

• Racetrack dimensions and orientation
• Vehicle reference position, including height and direction
• Vehicle dynamics; acceleration and speed

In the default “Off” state, SimGEN uses SVIDs 1 to 30. Once “Extended constellation” is selected, SimGEN can access SVIDs 1 to 30 and 31 to 63. The table below lists the satellite types and signals permitted for satellites in the constellation. Enabling “Extended constellation” also sets the AmEpID, AmID and BdEpID indicators in the Phase 3 D1 and D2 navigation messages - regardless of whether any extended constellation satellites are enabled in the scenario.

Continuous improvement with Spirent image

To view the full V6.06 Release Notes, please visit the Knowledge Base

Version 6.05 – February 2019

New ICDs supported

BeiDou Phase III

BeiDou ICD B1C V1.0 Dec. 2017 version

BeiDou ICD B2a V1.0 Dec. 2017 version

BeiDou ICD B3I V1.0 Dec. 2017 version


IS-MADOCA-SEAD Feb 2017 version

IS-QZSS-L1S-003 Nov 2018 version

IS-QZSS-L6-001 Apr 2018 version

IS-QZSS-PNT-001 Mar 2017 version


IRNSS_SISICD_SPS V1.1 Aug 2017 version

New features

SimGEN now has the added ability to force an additional BDS ephemeris update to occur at a specific time, away from the standard hourly update. This is to simulate the upload of new data from the control segment when an abnormality has been detected.

SimGEN also now allows customers to edit the .umt file and add comments and notes to your motion file. Supported customers can find out more in KB article SOL14088 on the Spirent Knowledge Base.

To view the full V6.05 Release Notes, please visit the Knowledge Base

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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.