A Time-varying Modulation Interference Suppression Method Based on Mutual Cancellation

Time-varying modulation targets disrupt the correlation between the echo signal and the reference signal by modulating the phase of the radar’s transmitted signal, thereby reducing pulse compression gain and significantly degrading radar target detection performance. Essentially, time-varying modulation targets impose a multiplicative interference on the radar signal. However, most existing suppression interference techniques are designed to counter additive interference, such as intermittent sampling repeater jamming. In this paper, a time-varying modulation interference suppression method based on mutual cancellation is proposed. Specifically, considering the characteristics of multiplicative interference and radar systems, this method involves the joint design of dual baseline transmission waveforms that are orthogonal in the frequency domain with constrained spectra and exhibit excellent matched filtering performance when multiplied in the time domain. Based on this, we formulate a non-convex optimization problem with the root mean square error between the weighted preset spectrum and the spectrum to be optimized as the objective function, and the constant amplitude of the transmitted signal as a constraint, proposing an effective solution method for this problem. Finally, some numerical simulation results are presented to validate the effectiveness of the proposed method.

I. Introduction

Time-varying modulation surfaces, which control the microscopic characteristics of reflected electromagnetic waves by rapidly switching the internal physical structure of materials, have recently been applied in radar interference, affecting target detection [1], tracking [2], and imaging [3]. Currently, in the field of radar, typical time-varying modulation surfaces include electromagnetic control surfaces (ECS), phase-switching screens (PSS), and modulation metasurface (MTS). In radar target detection, [1] utilizes ECS to generate a novel interference pattern that simultaneously impacts radar ranging and velocity measurement, while analyzing the effects of both periodic and random phase modulation on pulse Doppler radar.