Analysis STAP for Mixed Jamming Suppression and Subspace-Based Spoofing Cancellation Under Unknown Interference Conditions

Tsan-Lin Wu, Cheng-Wei Wang, Hsin-Cheng Liao, Shau-Shiun Jan

Peer Reviewed

Abstract:	This paper presents a compact four-antenna Global Positioning System (GPS) front-end pre-correlation processing framework that jointly addresses jamming and spoofing under unknown operating conditions. The key contribution is to detect whether the receiver is in a jamming, spoofing, or clean scenario and automatically switch to the corresponding suppression algorithm without requiring prior knowledge of the interferer's direction or parameters. For jamming, the framework monitors automatic gain control (AGC) variations to detect high-power interference at the front end. Once triggered, it performs space-time adaptive processing (STAP) using the minimum variance distortionless response (MVDR) criterion on intermediate-frequency (IF) samples. By augmenting each antenna channel with a finite impulse response (FIR) time delay filter, thereby simultaneously mitigating mixed narrowband and wideband jamming signals. For spoofing, we incorporate a calibration-tolerant pre-correlation detection and cancellation strategy that operates directly on raw in-phase/quadrature (IQ) samples. Notably, we generalize a previously dual-antenna pre-correlation spoofing canceller to a four-antenna architecture, leveraging additional spatial diversity to achieve more robust counterfeit suppression. By combining the two detectors, the receiver establishes a switching mechanism that reliably selects between jamming mitigation, spoofing cancellation, or pass-through processing in clean conditions. The proposed framework is validated through software simulations and outdoor measurements using a USRP X440 and a four-antenna front end. To emulate multi-jammer conditions without multiple hardware jammers, we digitally inject multiple synthesized jamming waveforms into outdoor-recorded clean GPS IF data. At the same time, spoofing is evaluated in both simulated and real-world environments. Results demonstrate concurrent suppression of at least nine narrowband and two wideband interferers, with average attenuation of approximately 25 dB for narrowband jamming, 25 dB for wideband jamming, and 20 dB for spoofing, enabling reliable acquisition and stable tracking under composite threats.
Published in:	Proceedings of the ION 2026 Pacific PNT Meeting April 13 - 16, 2026 Hilton Waikiki Beach Honolulu, Hawaii
Pages:	845 - 855
Cite this article:	Wu, Tsan-Lin, Wang, Cheng-Wei, Liao, Hsin-Cheng, Jan, Shau-Shiun, "Analysis STAP for Mixed Jamming Suppression and Subspace-Based Spoofing Cancellation Under Unknown Interference Conditions," Proceedings of the ION 2026 Pacific PNT Meeting, Honolulu, Hawaii, April 2026, pp. 845-855. https://doi.org/10.33012/2026.20625
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