Baltic sea GNSS jamming and spoofing emitter detection and localization in real-time using a time difference of arrival (TDOA) system

Reliance on GNSS continues to grow across the application space: from critical infrastructure to the burgeoning autonomy sector. At the same time, instances of radio frequency interference (RFI) affecting GNSS are becoming more widespread and can endanger lives with such dependence on GNSS. Currently, GNSS jamming and spoofing has become widespread around areas of conflict, especially surrounding Russia and Ukraine. But this has also spread more broadly and numerous reports, using Automatic Dependent Surveillance-Broadcast (ADS-B) aviation-based sensors, have come out of regions around the south Baltic Sea, significantly away from the current conflict regions. To explore the extent of the RFI, a low size, weight, power and cost (SWaP-C) GNSS monitor was deployed in Gdynia, Poland, which confirmed the presence of the RFI at the Gulf of Gdansk on the Polish coast. This initial effort was extended to deploy networked GNSS intermediate-frequency (IF) samplers around the Gulf of Gdansk on the Polish Baltic coast to further understand and attempt to localize the source of the interference using time-difference-of-arrival (TDOA). TDOA results are presented from the period of April-June 2025, where a circular spoofer was detected and localized, along with a separate jammer. The IF data allowed for the tracking of the circular spoofing signal, giving valuable insight into this emerging threat.