Interference Suppression Based on Joint Time-Frequency Analysis and Fractional Fourier Domain in LFM HF Radar

Radar signal is always contaminated by interferences in the high-frequency (HF) band because of the overcrowded electromagnetic environment today. This problem is more serious for linear frequency modulation (LFM) HF radar. In this paper, we put forward a three-step method to solve this problem. The new method detects interference based on time-frequency analysis technique, transforms the signal to fractional Fourier domain (FRFD), and finally suppresses the interference. Comparison between the proposed method and the traditional N-sigma method is given using simulation, and the results show that the proposed method is superior to the N-sigma method. Experimental results that the new method is applied for multi-frequency HF radar to obtain indicate that it can effectively suppress the interference with a SNR gain of more than 10 dB.