C/N0 Analysis-Based GPS Spoofing Detection with Variable Antenna Orientations

GPS spoofing poses a growing threat to aviation by falsifying satellite signals and misleading aircraft navigation systems. This paper demonstrates a proof-of-concept spoofing detection strategy based on analyzing satellite Carrier-to-Noise Density Ratio (C/N$_0$) variation during controlled static antenna orientations. Using a u-blox EVK-M8U receiver and a GPSG-1000 satellite simulator, C/N$_0$ data is collected under three antenna orientations flat, banked right, and banked left) in both real-sky (non-spoofed) and spoofed environments. Our findings reveal that under non-spoofed signals, C/N$_0$ values fluctuate naturally with orientation, reflecting true geometric dependencies. However, spoofed signals demonstrate a distinct pattern: the flat orientation, which directly faces the spoofing antenna, consistently yielded the highest C/N$_0$ values, while both banked orientations showed reduced C/N$_0$ due to misalignment with the spoofing source. These findings suggest that simple maneuvers such as brief banking to induce C/N$_0$ variations can provide early cues of GPS spoofing for general aviation and UAV systems.