Detecting Space Based Interference on GNSS Signals

GNSS receivers operate by relying on satellite signals coming from the Medium Earth Orbit (MEO), but these signals can easily be drowned out by background noise, underscoring the critical importance of interference detection. While traditional methods leaned on local spatial and temporal characteristics for this purpose, the advent of advanced widespread, multi-band GNSS receiver networks have significantly enhanced the capabilities of interference detection. This paper aims to investigate instances of interference by leveraging the Trimble reference network which consists of 43 multifrequency receivers deployed all over the US and Europe. In June of 2021, this network detected an unusual power spike within the B3/E6 band at 1268.52 MHz. Further monitoring and analysis unveiled a distinct interference pattern that eliminated the possibility of local jamming and instead pointed to a space-based origin. This conclusion was substantiated by the simultaneous impact on receivers across the entirety of Europe and the U.S. over a mere 24-hour span. This paper draws upon data collected from GNSS receivers scattered across these two continents to undertake interference monitoring. By analyzing averaged FFT (Fast Fourier Transforms) data in the B3/E6 band, the study correlates this information with LOS observables obtained from each receiver. Ultimately, the paper endeavors to determine the interference's global trajectory and pinpoint the most probable space-based origin. In addition, it attempts to assess any effects on a receiver position solution. Such monitoring is of paramount importance in safeguarding the quality and reliability of GNSS signals.