Main Lobe Interrupted Sampling Repeater Jamming Suppression Method Via Constructing a Time-Frequency Plane

Main lobe interrupted sampling repeater jamming (ISRJ) is a typical form of coherent jamming that achieves both deception and suppression effects, significantly degrading the detection and tracking performance of radar systems. On the basis of the periodic sampling mechanism of the ISRJ scheme and the consistent frequencies of jamming slices with the same repeater order after dechirping, we construct a time-frequency (TF) plane to suppress the ISRJ signals in the radar echoes. First, the dechirped echo signals are segmented and reshaped on the basis of the jammer's sampling interval to form a signal matrix. The energies of jamming slices with the same repeater order in different sampling intervals are then accumulated by applying a discrete Fourier transform to generate a TF plane. This plane, characterized by high time and frequency resolution and high energy concentration, facilitates the separation of target echoes from jamming slices and an accurate estimation of jamming parameters. The theoretical resolutions are derived, and the distribution characteristics of the target echoes and jamming slices in the TF plane are analyzed. On the basis of these characteristics, jamming slices are distinguished from target echoes, and key parameters such as the slice location and width are estimated. By zeroing the elements containing jamming signals in the TF plane, the ISRJ signals are suppressed. The numerical simulation results verify the feasibility of the proposed method, which shows stable performance under different jamming-to-signal ratios, signal-to-noise ratios and jamming parameters.