Brief

Our customer provides rugged communications systems for use in challenging environments. One of their core competencies requires testing using realistic SBAS and GPS L1 signals. The customer has record & playback (RPS) equipment, meaning they can perform repeatable tests using full real-world richness, and simulation equipment, meaning they can use mathematical modelling and edit the simulation parameters to test corner cases/challenging environments.

Our client asked us if we could analyse their recorded data and turn them into realistic test scenarios that could be played in the lab using a simulator. They wanted to do rigorous testing with their receiver and wanted the capability to edit simulation parameters. Of primary importance to the customer is the accurate representation of the recorded SBAS signals, as well as the realistic nature of the GPS L1 signals.

Approach

To enable our customer to reach their goals we adopted an approach defined by specified success factors. The baseline for the scenarios was generated by the customer, using a Spirent RPS in a static location. Spirent then replayed the recorded RF into a high-grade receiver in our lab, extracting parameters that included:

  • Scenario start time
  • Broadcasting SBAS PRN and position
  • SBAS degradation and ionospheric parameters
  • SBAS message types and rates
  • GPS track and clock errors
  • Atmospherics

We then downloaded the real orbit files for that period and entered them into the simulation. The ingenuity and expertise required in synthesising a truly realistic test scenario in this fashion meant that few people would have been able to achieve this in a reasonable timeframe.

Benefits

Our bespoke solution enabled our customer to test using the 2 best methodologies available combined into a single test solution, saving them both time and money.