A Novel GNSS RF Interference Detection and Geolocation Algorithm for LEO Satellites

With the rising incidence of Global Navigation Satellite Systems (GNSS) interference due to the current geopolitical climate, Radio Frequency Interference (RFI) is among the major challenges that GNSS receivers face, as it can cause significant errors in the reception of signals, affecting the accuracy and reliability of GNSS-based navigation and positioning systems. Characterization and mapping of RFI are challenging for space applications due to the significant free space losses that lead to weak GNSS-received signals. This makes the detection and localization of RFI from satellites a highly desirable capability for applications, including GNSS-Reflectometry, search-and-rescue, surveying and spectrum monitoring. This paper proposes an innovative algorithm for detecting and localizing GNSS interference based on mapping the Doppler shift and Doppler rate of a Low Earth orbit (LEO) satellite and an RFI transmitter. This work targets geolocation and mapping of RFI with different simulated scenarios using Skydel GSG-8 GNSS Simulator to simulate the space environment involving a single LEO satellite as a receiver and a static RFI transmitter source on the Earth’s surface. A novel, low-computation search grid aligned with the satellite path and upon the surface of the Earth is derived that improves search area capabilities and convergence rates. The geolocation grid has been developed with different grid resolutions and grid spacings to measure the accuracy of detecting the interference’s source. The influence of the Effective Isotropic Radiated Power (EIRP) on the RFI signals is discussed. The weakest transmission power is between -3.9 and 3.15 dBm depending on the path loss. The mean error between the truth Doppler rate and the measurement Doppler rate is 0.13 Hz/s. The geolocation algorithm result shows utilization and performance that converges within 7.4 seconds to within approximately 1-kilometre range of the true transmitter position over a 600 km search space.