Main lobe interrupted sampling repeater jamming suppression based on parameter estimation and channel cancellation

Abstract

The main lobe interrupted sampling repeater jamming (ISRJ), being coherent with the transmitted signal, is capable of generating both deception and suppression jamming effects. These effects severely limit the capabilities of monopulse radar to detect, track, and identify targets. Furthermore, since the jammer is located within the main lobe of the radar's transmit beam, spatial filtering techniques will cause a serious loss of target energy. This study focuses on the research on main lobe ISRJ suppression for monopulse radar. An anti-jamming scheme based on jamming parameter estimation and channel cancellation is proposed. Firstly, time-frequency (TF) analysis is performed on the received echo to estimate the ISRJ parameters using the distribution characteristics of TF energy. Subsequently, the time unit where only ISRJ signal exists is determined. A function, referred to as the sum-difference channel ratio, is constructed, and its value in the time unit where only ISRJ exists serves as the cancellation coefficient. By applying sum-difference channel cancellation, the jamming in radar's received echo is suppressed while retaining the real target simultaneously. Through numerical simulations, we have validated the effectiveness of the proposed method and conducted a thorough analysis of how different parameters affect its performance. Compared to state-of-the-art methods, the average improvement in the signal-to-jamming-plus-noise ratio improvement factor achieved by our method is approximately 6.4 dB higher.