Overview of weak interference detection and localization techniques for the GNSS environmental monitoring system (GEMS)

Modern infrastructure increasingly relies on the positioning and timing capabilities provided by the Global Navigation Satellite Systems (GNSS) such as GPS, making GNSS itself a critical infrastructure. Low received signal power levels of GNSS signals, however, make them vulnerable to unintentional and intentional Radio Frequency Interference (RFI). Alleviating this vulnerability to interference by detecting, localising and eliminating it has become of paramount importance. In this paper we provide an overview of various weak RFI detection and localization techniques that were developed for the GNSS Environmental Monitoring System (GEMS) II that uses hybrid Angle-of-Arrival (AOA) and Time-Difference-of-Arrival (TDOA) techniques to geo-locate RFI. The use of these approaches results in increased interference detection and localisation capability, hence increasing the coverage area of the GEMS II system. This enables GEMS II to detect the onset of interference before it effects the operation of the systems that rely on GNSS to function.