Novel Anti-spoofing Methods Based on Discrete Wavelet Transform in the Acquisition and Tracking Stages of Civil GPS Receiver

摘要

The growing dependence of critical civil infrastructure on Global Positioning System (GPS) makes GPS interference not only a safety threat, but also a matter of national security. Spoofing could pose a major threat for GPS navigation systems, so the GPS users have to gain an in-depth understanding of GPS spoofing. Therefore, spoofing countermeasure is a significant subject of research these days. In this paper, we utilize wavelets transform (WT) as a tool that effectively hinders the adverse activities of these groups, and then introduce two novel methods to mitigate spoofing in the acquisition and tracking processes. In the first suggested algorithm, using WT in the acquisition process, we control satellite constellation to mitigate spoofing errors. After generating the in-phase and quadrature correlator output signals, called I and Q respectively, we apply the wavelet db3 to the Q samples to remove their noise components. In the second method, WT is used in a tracking loop. In this way, we apply sym4 to the Q arm, which results in spoofing reduction. We apply our new algorithms to both simulated and measurement data sets, to shed light on its performance. Results show that both methods successfully mitigate the spoofing effect on the tested data sets.