Joint Design of Waveform and Mismatched Filter for Interrupted Sampling Repeater Jamming Suppression

The interrupted sampling repeater jamming (ISRJ) produces multiple false targets after pulse compression, making it difficult for radar to detect real targets. In this article, an anti-ISRJ algorithm is developed based on the joint design of the waveform and the mismatched filter with an expanded mainlobe. First, to prevent false alarms when the range sidelobes and jamming peaks of the filter output are too high, the sum of the peak sidelobe level of the waveform compressed with the mismatched filter and the peak level of the ISRJ signal compressed with the mismatched filter is taken as an optimization criterion for minimization. Meanwhile, a penalty function is used to control the mainlobe shape of the correlation function between the waveform and the mismatched filter to approximate the desired mainlobe. To maximize the transmitted power efficiency of the radar and control the signal-to-noise ratio loss caused by the mismatched filter, a constant modular constraint for the waveform and an energy constraint for the filter are adopted. Then, an iterative algorithm based on the majorization-minimization framework is proposed to solve the joint design problem. In each iteration, an analytical expression is derived to realize the simultaneous updating of the waveform and filter. The convergence of the proposed algorithm is proven, and its computational complexity is analyzed. Finally, simulations are provided to demonstrate the effectiveness of the proposed algorithm. Compared with existing algorithms, the waveform and filter designed in this article exhibit better pulse compression performance and antijamming ability.