Contrastive analysis of the performances of radar multi-look polarimetric detectors

Abstract

Contrastive analysis of the performance of 7 classical polarimetric detectors is presented for multi-look case after extending the identity likelihood ratio test (ILRT), the optimal span detector (OSD) and the single channel detector (SCD). The ideal detection performances of the optimal polarimetric detector (MOPD), the multi-look polarimetric matched filter (MPMF), the multi-look polarimetric whitening filter (MPWF), the multi-look span detector (MSD) and the above three after extended are compared by using Monte Carlo simulations and the analytical method respectively, since two kinds of general mathematical expressions of the theoretical performances of the SD, OSD and SCD are derived for multi-look case. Area under the ROC curve (AUC index) and the concept of ‘gain of multi-look processing’ are first used to evaluate these detectors, while the results indicate that the optimum number of nominal look is 4 for polarimetric radar under low and medium resolution, and the ranking result for 4-look case is obtained, that is, OPD > MPWF ≈ MILRT (multi-look ILRT) > MOSD > MPMF ≈ MSD > MSCD. The adaptive detection performances are analyzed at the same time, which demonstrates that polarimetric detectors perform well when observation number is greater than 32 for 4-look case while 64 for single-look case. Finally, a novel approach to compute the CFAR threshold of the span detectors is proposed by using the theoretical threshold derived in this paper.