Whitepaper

Real-World Interference Impacts Analysis using High Dynamic Range GNSS RF/IF Signals R&P

Robustness consideration in GNSS receivers’ design and validation still represent a big challenge as multiple RF sources must coexist in an overloaded RF world. Despite the advantages of spectrum spreading techniques used in GNSS, receivers are still vulnerable to interferences generated by a variety of sources (FM/TV transmitters’ harmonics, mobile phone networks, AM transmitters, location based services transmitters, etc.). Most of the research and analysis done in this area are based on the GNSS simulators. Simulated GNSS signals are combined with RF interferences at the GNSS receiver RF input, bypassing the active GNSS antenna. Although very efficient, these methods still lack reproducing realworld signal impairments with high fidelity. To complete the analysis of GNSS receivers’ performance in presence of interferences and to have a better understanding of the interferences’ impacts on real-world GNSS signals, field tests are mandatory. The interferences’ impact on GNSS signals analysis in the field is not always easy to perform in real-time, especially when the experiment conditions are subject to constant changes. Also, field tests are usually cost- and time-consuming (e.g. flight tests, special environments, complex scenarios, repeatable tests and controlled conditions, etc.). In the proposed interferences’ analysis approach, the real GNSS and interference signals are first recorded with a Multifrequency Record and Playback system (like a snapshot of the real-world RF spectrum) in a large frequency band with a high dynamic range. The recorded data (GNSS plus interference signals) are postprocessed in order to analyze the GNSS signal degradation and to characterize the nature of the interferences dropped into the GNSS spectrum (out of band interferences are considered). The real-world RF signals, once recorded can be replayed at any time in a controlled environment for any GNSS receiver testing, proof of concept and demonstrations or technological breakthrough