Brief

Our client was experiencing intermittent loss of service of GPS receivers in one of two locations, but not in the other. There were several potential causes of the observed issues, with the most likely seeming to be radio frequency interference (RFI). Our brief was to establish the cause of the PVT degradation/outages, demonstrate how it was affecting the client’s equipment, and offer mitigation solutions.

Approach

In order to perform this analysis effectively a wide range of equipment was required, as well as a high level of expertise. Our professional services team was able to fulfil both of these needs, and was a cost-effective way for the customer to achieve their aims.

We split our approach into three distinct parts. Firstly, we took a recording at the affected site using a GSS6450 Record-and-playback (RPS) device. We then replayed the recorded RF data file into a spectrum analyzer to determine the duration of interference signals, and the frequency band within which they occur. This gave us a picture of the power and duration of interference over an extended period, providing a benchmark to test against.

The second stage of the service involved benchmarking the client receiver performance against two high-performance COTS receivers. To do this we replayed the recorded RF data file into the receivers and analyzed their behavior in terms of 3D accuracy, number of visible GPS satellites, C/N0, and PVT outages. This allowed us to demonstrate that a different receiver would be less seriously affected by the observed interference.

Lastly, we replayed the recorded RF data file into a GSS200D interference detector. From there we were able to synthesize test cases that could be used in the lab. This allowed the client to regulate and justify their vendor selection, perform software optimization, and improve receiver positioning.

Benefits

After delivery of our reports and analysis the customer was able to pinpoint the sources of RFI that had been causing issues for their systems. Using that information, as well as the test cases we synthesized for their ongoing use, the client was able to make an informed decision on the receiver used in their systems, as well as where the receiver would be best positioned to deliver a continuous service. All of this was done for a fraction of the cost of purchasing each individual piece of hardware used in the process, not to mention the expertise required to operate the hardware.