GPS OTA jamming system development and verification with off-the-shelf receiver

Abstract

The resilience of Global Navigation Satellite System (GNSS) receivers against intentional radiofrequency (RF) threats was investigated by building a repeatable over-the-air (OTA) jamming and spoofing testbed that couples a Safran Skydel signal generator, an Ettus Universal Software Radio Peripheral (USRP) X300 software-defined radio and a u-blox M8 L1 receiver. Three representative interference waveforms were radiated con-tinuous-wave (CW) tone, 1 Mbps Binary Phase-Shift Keying (BPSK) noise and a ±5 MHz linear-FM chirp while a counterfeit GNSS transmitter (“spoofer”) remained co-channel but power-controlled. Experiments were executed first through a link (conducted) and then inside an anechoic chamber at 0.5 m and 1.35 m receiver distances, compo-site signals were radiated. S/J was calculated at 1 kHz using logged receiver and jammer power to assess tracking and recovery under deep fades.

Results show that waveform performance depends strongly on both geometry and transmit power. At the close 0.5 m range, chirp achieved the highest mean signal-to-jammer ratio (–1.4 dB) and fastest recovery, outperforming CW (–1.7 dB) and BPSK (–2.1 dB). S/J was calculated using logged receiver and jammer power. When separation increased to 1.35 m, the order inverted: narrow-band BPSK led (–7.8 dB) because the additional 8.6 dB path-loss lowered jammer power below its coherent-integration gain, while chirp and CW fell to –13.3 dB and –22.4 dB respectively. All catastrophic outages aligned with the jammer’s closest approach, underscoring geometry as the primary driv-er of worst-case behaviour.

The study validates the testbed as a cost-effective bridge between simulation and field trials and emphasises the need for adaptive waveform selection and geometry-aware countermeasures in future GNSS receiver designs.