Optimum coherent detection in homogenous K‐distributed clutter

Abstract

In this study, the optimum coherent detector in homogeneous K-distributed clutter is derived. It is named the Hom-OKD to show its relationship with the optimum K-distributed detector (OKD) under highly heterogeneous K-distributed clutter. The Hom-OKD has a different expression from the OKD because the received vectors at the reference cells are used as a part of the hypotheses. The Hom-OKD is shown to be constant false alarm rate (CFAR) with respect to speckle covariance matrix, Doppler steering vector, and the scale parameter of the gamma texture. Moreover, the adaptive Hom-OKD using a non-iterative maximum likelihood estimate of speckle covariance matrix is given and is proved to have the same CFAR property as the Hom-OKD. Under homogeneous K-distributed clutter environments, the adaptive Hom-OKD provides better detection performance than the adaptive OKD owing to the fact that the texture information conveyed by the secondary data at the reference cells is fully exploited. Simulated experiments are used to verify the optimality of the Hom-OKD. Experiments using real sea clutter data are made to show that the adaptive OKD and adaptive Hom-OKD are complementary. The former surpasses the latter for highly heterogeneous sea clutter and the situation is converse for homogeneous sea clutter.