Mitigation of thunderstorm interference in compact HFSWR by space-time cascaded processing

Transient interference can significantly degrade the performance of high-frequency (HF) radars. Most previous studies have focused on skywave over-the-horizon radar assuming that interferences are sparse in coherent integral time (CIT). However, HF surface wave radars often experience more severe transient interference than skywave radars because of extreme weather conditions such as thunderstorms and typhoons. Traditional methods suffer dramatic performance degradation since these interferences substantially contaminate parts of CIT. In this study, we propose a novel interference suppression method based on adaptive beamforming and a modified space-time cascaded process. The proposed procedure has two main aspects. First, based on the spatial correlation of a compact array, statistical samples of main-lobe transient interferences are estimated using rotating spatial beam technology. Second, a time domain-adaptive selection strategy based on information geometry is developed to obtain optimal training samples of the interferences. The proposed method was evaluated using the measured data, and the processing results demonstrated its effectiveness.