Interrupted Sampling Repeater Jamming Suppression Based on Inter-Pulse Frequency Coding LFM Signal and Mismatch Filter

Interrupted sampling repeater jamming (ISRJ) exhibits unparalleled coherence, high agility, and rapid response compared to other jamming types, while simultaneously possessing both blocking and deception effects. Consequently, the threat posed by ISRJ to radar systems in engineering applications is becoming increasingly severe. Particularly with the continuous emergence of ISRJ variants and forwarding strategies, traditional anti-jamming methods appear inadequate. To address this challenge, we propose an ISRJ suppression method based on inter-pulse frequency coding LFM (IFC-LFM) signal and mismatch filter. First, an IFC-LFM signal is designed at the transmitter, and the echo signal undergo mismatch processing using an uncoding LFM pulse train. Subsequently, the mismatch-processed output pulses of the entire coherent process interval (CPI) undergo ISRJ cancellation in the slow-time domain using blind source extraction (BSE) technology. During ISRJ cancellation, the mismatch filter is constructed based on the frequency coding of the transmitted signal. The mismatch filter reference signal can adaptively eliminate signal segments sampled by ISRJ. Finally, all pulse echoes in the entire CPI are processed through the constructed mismatch filter, followed by range Doppler processing and target detection, achieving effective ISRJ suppression. Numerical results demonstrate that the proposed method effectively suppresses both conventional and complex ISRJ types, including frequency shifting ISRJ, nonperiodic ISRJ, and composite ISRJ. Compared to existing algorithms of the same type, the proposed method exhibits superior anti-jamming performance and has a wider applicability.