A Spoof-Proof GPS Receiver

We present a precise and robust GPS spoofing mitigation method, which is based on a position likelihood distribution. Compared to existing spoofing mitigation methods, this maximum likelihood method is less prone to selecting the wrong satellite signals when (spoofed) duplicates are received. The presented method operates from GPS signal snapshots as short as one millisecond and detects all likely receiver positions. Even with spoofing signals stronger than the authentic satellite signals, the actual receiver position is still found through iterative dampening of the strongest signals. The spoofing mitigation capability is evaluated on the de facto standard TEXBAT spoofing dataset. We reach median position errors introduced by spoofing below 19 m and keep the maximum error below 222 m for all TEXBAT scenarios. This is six times more accurate than the best previous work, which only detects spoofing attacks, but does not mitigate them.