Performance analysis of order-statistic CFAR detectors in time diversity systems for partially correlated chi-square targets and multiple target situations: A comparison

In radar systems, detection performance is always related to target models and background environments. In "time diversity systems", the assumed Swerling complete correlation (slow fluctuation) and complete decorrelation (fast fluctuation) target models may not predict the actual system performance when the target returns are partially correlated. The probability of detection is shown to be sensitive to the degree of correlation among the received pulses. In this paper, we derive exact expressions for the probability of false alarm (Pfa) and the probability of detection (Pd) of a pulse-to-pulse partially correlated target with 2K degrees of freedom in a pulse-to-pulse completely decorrelated thermal noise for the order statistics constant false alarm rate (OS-CFAR) detector and the censored mean level CFAR (CMLD-CFAR). The complete analysis is carried out for the "non-conventional time diversity system" (NCTDS) and multiple target situations. The obtained results are compared with the detection performance of the "conventional time diversity system" (CTDS).