Multiwindow hierarchical range-spread target detection in high-resolution sea clutter

High-resolution maritime radars often operate on complex scenes with dense small targets and range-spread targets in coastal waters. Traditional range-spread target detectors suffer from significant loss due to the mismatch between the range integration window and target radial sizes, and severe interference from range-spread targets to detection of surrounding small targets. In this paper, a multiwindow hierarchical range-spread target detection method is proposed to address target detection in complex oceanic scenes. High-resolution sea clutter is modelled by the generalized Pareto distribution. Adaptive range-spread generalized likelihood ratio test linearly threshold detectors (GLRT-LTDs) using multiple range integration windows are cooperated to reduce the mismatch loss. The detection results using wider range windows serve as prior information on scenes, aiding detection using narrower range windows in selection of reference cells. The hierarchical utilization of scene information markedly improves detection performance of small targets around range-spread targets. In addition, the mismatch loss of range windows in range-spread GLRT-LTDs are analyzed, and a fast estimation and inversion algorithm of speckle covariance matrices is given to mitigate computational burden of the multiwindow hierarchical detection. Finally, measured data with test small target and simulated range-spread targets is used to verify the effectiveness of the proposed method.