Fusion-Based Adaptive Coherent Detection of Small Targets in Dual-Polarimetric Correlated Sea Clutter

Polarization diversity has been widely used in maritime radars to improve detection performance. For high-resolution maritime radars for small target detection, the HH-HV dual polarization is an affordable and effective mode. This article investigates dual-polarimetric coherent detection in dual-polarimetric compound-Gaussian sea clutter with correlated inverse Gamma textures at two polarizations. The analysis of real measured datasets shows that the textures at HH and HV polarizations are highly positively correlated. The existing dual-polarimetric coherent detectors are all based on the texture independency assumption and, thus, suffer from severe model mismatch loss. A dual-polarimetric signal-to-clutter ratio-based fusion detector, for short, the DPSF-GLRT-LTD, is proposed, which is free of the texture independency assumption. It is proved to be constant false alarm rate with respect to the Doppler steering vector, scale parameters, and speckle covariance matrices. Moreover, the false alarm rate of the DPSF-GLRT-LTD is shown to be insensitive to the texture polarimetric correlation coefficient by Monte-Carlo tests. Experiments using the measured sea clutter data with simulated targets and test targets are made to compare the proposed DPSF-GLRT-LTD with the existing dual-polarimetric coherent detectors. The results show that the DPSF-GLRT-LTD attains much better target detection performance.