Research on ISRJ Suppression for LFM Signals Based on Frequency-Domain Feature Adaptive Mismatched Filtering

Le résumé fourni par la source

Intermittent Sampling Repeater Jamming (ISRJ), a typical coherent interference, poses a severe threat to stable radar target tracking by intercepting and repeatedly retransmitting portions of radar pulses, which generates dense false target clusters with high coherent processing gain in the range domain. To address the failure of traditional spatial anti-jamming methods in self-defense scenarios, this paper proposes an ISRJ suppression method based on frequency-domain feature extraction and adaptive mismatched filtering. Firstly, the de-chirp technique is utilized to perform time-frequency transformation on singlechannel echoes, accurately identifying the jammer's sampling period and slice width by extracting “bright-line” spectral features. Subsequently, an adaptive mismatched filter is constructed based on a time-domain zeroing criterion using the extracted parameters. To accommodate parameter estimation deviations, a$\mathbf{1. 5}$-fold redundant width zeroing window is introduced, achieving precise directional notch filtering of the jamming mainlobe energy through sliding window displacement. Finally, a moving average algorithm is applied to repair and smooth the envelope in the notched regions of the filter output, thereby preserving the structural integrity of the target echo. Simulation results demonstrate that within a Jamming-to-Signal Ratio (JSR) range of -10 dB to 30 dB, the proposed method maintains a high and stable Signal-to-Interference-plus-Noise Ratio (SINR) improvement factor. Its performance significantly outperforms traditional matched filtering and down-sampling blind source separation methods. The proposed method requires no complex waveform coding, does not rely on spatial separability, and exhibits high robustness to jamming parameter estimation errors, providing an efficient and steady engineering solution for radar signal processing in complex electronic countermeasure environments.

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