Interrupted Sampling Repeater Jamming Suppression Method Based on Time-Frequency Domain Statistical Characteristics

Interrupted sampling repeater jamming (ISRJ) is a type of coherent interference that works by sampling and retransmitting radar signals multiple times within a single radar pulse, creating realistic false target groups at the radar receiver that severely interfere with target detection and recognition. Current research primarily focuses on suppressing ISRJ in radar received signals after de-chirping processing, while studies on suppressing ISRJ in received signals after pulse compression remain relatively scarce. To address this issue, this paper proposes a method that identifies jamming and target echoes by utilizing their fluctuation characteristics in the time-frequency domain, thereby achieving jamming suppression. First, short time Fourier transform (STFT) is applied to the matched-filtered received signals to obtain their time-frequency distribution. Then, threshold detection is performed on the time-frequency matrix to obtain over-threshold points corresponding to potential jamming and target echoes. Subsequently, the coefficient of variation of frequency dimension (CVFD) is calculated for the at each time sampling point where over-threshold points exist. By comparing with CVFD threshold, the system can identify whether the frequency-domain components correspond to jamming or target echoes. Finally, a time-frequency domain filter is constructed based on the identification results to suppress the jamming. Simulation results demonstrate that the proposed method effectively suppresses intermittent sampling repeater jamming.