Detection Loss Due to Interfering Targets in Ordered Statistics CFAR

0018-9251188/1100-0678 $1.00 (C 1988 IEEE Ordered statistics (OS) constant false alarm rate (CFAR) algorithm, introduced by Rohling [ I ] , is a CFAR technique with special immunity to interfering targets. CFAR usually suffers some detection loss due to the adaptive threshold concept. Furthermore, the presence of strong returns among the cells used to determine the background noise or clutter (reference cells), results in an increase in the threshold, and therefore an increase in the required signal strength of the desired target. This is in effect an additional detection loss. In some CFAR methods, the presence of a strong return among the reference cells can cause a drastic reduction in the probability of detection. OS CFAR is a detection technique in which the threshold is just a scalar times one of the ranked reference cells. This concept provides inherent protection against a drastic drop in performance in the presence of interfering targets. In OS CFAR interfering targets cause only gradual detection loss. This loss can be analytically calculated when the interfering targets yield very strong returns, and when the desired target is a Rayleigh fluctuating one.