Interrupted Sampling Repeater Jamming Suppression via Mismatch Filter Constructed by Multi-frequency Compensation

Interrupted sampling repeater jamming (ISRJ) has garnered significant attention in recent years. With the advancement of jammer technology, an increasing variety of ISRJ types and strategies have emerged, including frequency shifting ISRJ (FISRJ), nonperiodic ISRJ (NISRJ), and composite ISRJ (CISRJ), among others. This presents a challenge to anti-jamming technology. Many existing anti-ISRJ methods heavily rely on obtaining accurate prior knowledge of jamming and can only suppress ISRJ types with strong regularity. In response to this issue, this paper proposes a mismatch filter-based approach for ISRJ suppression. It cleverly formulates the construction of mismatch filters as an optimization problem with independent constraints through multi-frequency compensation. Initially, multi-frequency compensation is performed on the reference signal of a single echo to obtain multi-channel matched filtering outputs. Subsequently, the multiple outputs are processed by the independent component analysis algorithm, constructing an adaptive mismatched filter through independence constraints. The resulting mismatched filter can preserve the target energy while effectively suppressing the energy of ISRJ. Numerical simulations demonstrate that this method does not require any prior knowledge of ISRJ and is capable of suppressing ISRJ across various forwarding strategies, including FISRJ, NISRJ, and CISRJ. It exhibits high robustness to variations in noise and jamming energy.