Combating Compound Interference in Radar-Communication Spectral Overlap: A Cognitive Framework via Multi-Null Spectral Masks

Abstract

In spectrum-congested environments, radar systems may simultaneously suffer from interrupted sampling repeater jamming (ISRJ) generated by digital radio frequency memory techniques and spectrally overlapping communication interference. To address this compound-interference problem, this paper proposes a joint transmit–receive framework based on alternating-bandwidth transmission (ABT) and multi-null spectral masks (MNSMs). At the transmitter, pulse-to-pulse variations in bandwidth and initial frequency of the transmitted signal introduce waveform-dependent pulse-compression response diversity, thereby weakening the slow-time coherent accumulation of ISRJ-induced secondary false targets and sidelobes. At the receiver, a common communication null and graded multi-null spectral masks generate multiple range–Doppler planes with differentiated spectral supports and interference responses. Real and false targets are then discriminated through peak compensation, range–velocity matching, and cross-plane peak-fluctuation analysis. The target-energy loss caused by spectral nulling is also analyzed. Simulation and semi-physical results demonstrate that the proposed framework effectively suppresses compound interference while preserving real-target responses and enabling reliable false-target discrimination under low signal-to-noise ratio and high jamming-to-signal ratio conditions.