A New Method for AOA Estimation and TDOA/AOA Joint Localization of GNSS Spoofer

One of the crucial issues in mitigating Global Navigation Satellite System (GNSS) spoofing is direction finding and localization of spoofing interference sources. GNSS spoofing signals share the same signal structure as authentic signals, leading to challenges such as undetected spoofing, inability in separating spoofing from authentic signals, difficulties in spoofing identification, and inaccuracies in measurements using conventional strong interference monitoring systems and classical emitter direction-finding and localization methods. To address this issue, this paper proposes an Angle of Arrival (AOA) estimation method based on spatial cross-correlation power spectrum peak search and a GNSS spoofing interference source localization method that integrates Time Difference of Arrival (TDOA) and AOA observations. First, a spectrum peak search is conducted within the spatial angle range to detect spoofing and extract signal power and AOA observations from different incident directions. Second, signals from the reference antenna element are processed at the baseband level to enhance spoofing detection by dual-peak detection, separate spoofing from authentic signals by maximum likelihood estimation in the multi-correlator receiver, and group spoofing and authentic signals by calculating their pseudorange residuals. Then the spoofing signals are identified by comparing spatially-observed Angle Difference of Arrival (ADOA) with receiver-solved ADOA. On this basis, time synchronization across multiple monitoring stations is achieved, facilitating the extraction of TDOA observations from spoofing sources. Finally, by utilizing the identified AOA-TDOA observations of the spoofing signals, precise localization of spoofing sources is achieved. Simulation results demonstrate that our method can not only effectively detect and identify spoofing signals, but also accurately locate multiple spoofing sources simultaneously using only three or more base stations.