Countermeasure for Interrupted-sampling Repeater Jamming based on Fractional Fourier Transformation

Today, the interrupted-sampling repeater jamming (ISRJ) has posed a serious threat to LFM radars. In this paper, a countermeasure to suppressing ISRJ based on fractional Fourier transformation (FrFT) is presented. The echo signals, mixed with ISRJ, will be processed in FrFT of specific order, and then a narrow band filter based on parameters of FrFT is designed to extract the target signals and suppress interference signal, so as to realize the target detection. The three kinds of models of ISRJ (ISDRJ, ISRRJ, ISCRJ) are introduced; the anti-jamming principles are analyzed and simulated. The simulation results show that, the algorithm has low complexity and takes short operation time, and it is effective in low SNR or high JSR condition