Antenna diversity—employing either multiple separate receivers or a multi-antenna single-oscillator receiver---can be used to defend against intentional GPS spoofing by greatly increasing the technical difficulty required to mount a successful attack. In general, an additional spoofer transmitter is required for each additional GPS antenna. Furthermore, a spoofer would have to locate each transmit antenna in close physical proximity to the appropriate GPS antenna in the array. If the GPS antennas of static or dynamic installations are further protected by physical security, it is possible to create a robust defense against even a sophisticated spoofing attack. In the case of a complicit user, the presence of multiple antennas makes it difficult to intentionally defeat the system by direct injection of an artificial GPS signal. In the spoofing defense implemented here, a one-time survey of a fixed antenna array was sufficient to enable receiver autonomous spoofing detection. a practical but slightly less robust defense that does not depend on knowledge of the attitude of the multi-antenna array can also be implemented. The technology to enable multi-antenna spoofing detection is readily available using any of the numerous GPS receivers that produce L1 carrier phase observables.

 

Cite and download the paper:
Montgomery, P.Y., T.E. Humphreys, B.M. Ledvina, "A Multi-Antenna Defense Receiver-Autonomous GPS Spoofing Detection," InsideGNSS, 2009.