GMV NSL's unprecedented understanding of the threats and vulnerabilities to GNSS and the RF environment, allows us to test GNSS-based units in terms of their security, functional and operational performance.


GMV NSL provides services to test commercial devices that have been submitted for type approval against detailed functional and non-functional requirements. This includes, for example:

  • Testing the performance of single-constellation, multi-constellation and augmented GNSS
  • Performance testing under nominal, degraded and denied scenarios
  • Testing the Time-To-First-Fix and other performance metrics in the presence of obstructions
  • Testing the communications system performance and power management capabilities
  • Testing the resilience against signal interference, spoofing and jamming
  • Testing the vulnerability to tampering and unauthorised external inputs
  • Analysis of the reporting history to identify event characteristics and derive common indicators for incidents, attacks and aberrations
  • For further information on these services, please either email or telephone GMV NSL.


GMV NSL are the leading civilian authority on radio interference of the GNSS frequencies and signals. Our DETECTOR product has been developed to capture and analyse rogue interference signals.

DETECTOR comprises of GNSS hardware and server-based analysis and alerting software. The hardware continuously listens to the GNSS signals, capturing any abnormal RF signals that may occur. These signals are then analysed, their impact on PNT assessed, characterised in terms of interference type (for example this may be the type of GNSS jammer that is present), and parameterised so that the signal may be regenerated in a controlled environment for receiver testing purposes.


Key Features and Benefits

  • DETECTOR probes detect and record real-world interferences to the GNSS signal
  • Radio Frequency signal captures are characterised, categorised and parameterised with all information stored in a relational database for analysis
  • Event alerts are sent to users via email and/or text message based on user-defined trigger events
  • Manufacturers, integrators and purchasers of GNSS receivers can monitor their GNSS signal environment to understand the scale and severity of the threats
  • Service providers can ensure that their system is clean and free from interference
  • GNSS developers and service regulators can test their systems in the presence of captured interferences
  • GNSS developers can develop hardened receivers that are resilient to real-world interference signals

GNSS ENVIRONMENT: Solutions for recording, analysing & impact Assessment

GMV NSL offers a complete set of tools to monitor the quality of satellite navigation. With each tool offering state of the art capability, the combined set creates the world’s most comprehensive solution for safeguarding your GNSS investment.


monitoringtoolsCapability of NSL's GNSS Environment tools

These tools are tried and tested across numerous market sectors including aviation, maritime, timing, critical infrastructure and communications, and include:

  • GISMO - software that analyses the measurements from GNSS satellites
  • DETECTOR - hardware that records, and software that analyses, the RF signals in the GNSS spectrum
  • SAGE - professional-grade reference station hardware to record measurements from GNSS satellites
  • TESTING SERVICES - a combination of tools, facilities and resources to test end to end GNSS based systems






The GISMO (GNSS Integrity and Signal Monitoring Observatory) is a software-based service that meets the needs of organisations that provide GNSS-based products and services reliant on a minimum level of performance from GNSS. For example, GISMO is operational at international airports that support GNSS-based aviation procedures (R-NAV).

GISMO provides a full analysis of GNSS positioning and timing for any particular application, providing metrics on a 24/7 basis. This software suite can operate with any GNSS network which provides dual-frequency code and carrier data.

GISMO produces graphical and descriptive results, which can either be displayed online or used to generate periodic reports. The system is capable of the following distinct monitoring services.

  • Satellite availability, accuracy and integrity
  • Signal reception and signal quality statistics
  • Identification of faults and failures
  • Record of published NANUs
  • Comparison of NANU information and monitored GPS constellation behaviour
  • Satellite range error analyses
  • Station error analyses and modelling
  • Predicted satellite availability, accuracy and integrity
  • Comparison between predicted and observed values
  • Ensuring GPS is meeting the criteria specified within "Global Positioning System Standard Positioning Service (GPS SPS) Performance Standard - 2008"
  • Ensuring GPS is meeting the criteria specified within "ICAO SARPS (2006), Annex 10: International Standards and Recommended Practices"