Dual-antenna GNSS spoofing detection method based on Doppler frequency difference of arrival

Recent years have witnessed the emergence of portable global navigation satellite spoofing devices. A variety of anti-spoofing techniques have been dedicated to detecting the presence of spoofing signals, most of which solely utilize either signal characteristics or navigational information. However, since the GNSS system is under continuous monitoring and control, there is a subtle consistency between the signal and the navigational information in authentic GNSS signals, which the spoofing signal can hardly counterfeit. Here, we present a new dual-antenna spoofing detection technique based on this consistency. The essence of this method is the precise estimations of the frequency difference of arrival between a pair of fixed antennas from both the carrier phase observations and the navigational information. When there is no spoofing signal, the observation should be consistent with the prediction. Otherwise, spoofing signals would probably break the consistency because of the geometric and motion discrepancies between GNSS satellites and the spoofing device(s). Theoretically, since the proposed method does not make any presumptions about the spoofer, it can detect moving spoofers and multi-antenna spoofers. We analyze the optimal detection method in three different situations, and the corresponding detection performances are both theoretically and numerically investigated. We also intensively conduct experiments with various configurations to prove the detection capabilities against various spoofing techniques and strategies.