Robust Iterative Adaptive Filtering Sidelobe Suppression Algorithm to Range-Doppler-Straddling

The sidelobe suppression performance of existing iterative adaptive filtering methods severely deteriorates in the presence of range-Doppler-straddling targets. To resolve this issue, a straddling-robust iterative adaptive filtering (SR-IAF) algorithm is proposed. It incorporates the range-Doppler-straddling and intrapulse Doppler effects into the received signal model and compensates the straddling mismatch iteratively using the estimated straddling offsets. To further improve the capability of SR-IAF for sidelobe suppression in scenarios including range-spread targets, a modified SR-IAF (MSR-IAF) algorithm is then proposed. In this algorithm, the coarse positions, the lengths, and the number of range-spread targets are first determined according to the SR-IAF outputs, then the straddling offsets of range-spread targets are refined based on the minimum error criterion, and finally, SR-IAF is again performed with the estimated range–Doppler image and straddling offsets as prior knowledge to further subdue sidelobe levels of range-spread targets effectively. Simulation results show that the proposed SR-IAF method is capable of recovering the range–Doppler images with well-suppressed sidelobes for point straddling targets, resulting in successful detection of weak targets located near strong targets. Compared with SR-IAF, MSR-IAF can further improve the performance of sidelobe suppression for range-spread targets with straddling, as demonstrated by the simulated and the experimental results.