Abstract: Aiming at the complicated strong interference overlapped on the weak GPS signal in time and frequency domains, and motivated by the idea of signal cancellation, a method for mitigating the strong interference in the cyclic spectral domain is proposed. First, the cyclic frequencies (CFs) of the interference are obtained by the cyclic spectral analysis; then with the obtained CFs and the adaptive FREquency SHift (FRESH) filter, a detailed process of mitigating the strong interference by the FRESH filtering is formed; finally by implementing the FRESH filtering with the adaptive least mean square (LMS) algorithm, the strong overlapped interference can be effectively mitigated. Simulations on the acquisition and tracking of performance of the separated GPS signal after the interference mitigation under different circumstances validate the proposed method.

Key words: GPS signal, time and frequency overlapped interference, cyclic spectral analysis, FRESH filtering