A multi-domain collaborative filter for HFSWR based on oblique projection

Radio frequency interference (RFI) cancellation is a main problem to be solved in High Frequency Surface Wave Radar (HFSWR) system. To minimize the impact of RFI, a number of signal processing techniques, such as adaptive beamforming and polarization filtering, have been developed. However, the performance of these conventional methods degrades a lot when the target and interferences have similar parameters within the corresponding processing domains. According to the fact that target usually differs with RFI in more than one domain, it will be beneficial to suppress interferences by constructing a joint filter that includes multiple domains like frequency, space and polarization, etc. In this paper, a multi-domain collaborative filer (MDCF) based on oblique projection is proposed. The construction of oblique projection spatial-frequency-polarization filter (OPSFPF), oblique projection spatial-polarization filter (OPSPF) and oblique projection spatial filter (OPSF) is introduced. Theoretical analysis and simulation results demonstrate that the multi-domain collaborative filter is feasible and performs better when more processing domains are included. Such filter could take full advantage of the differences between the target and interference and, consequently improves the effect of RFI suppression in HFSWR.