Postdetection integration analysis of the excision CFAR radar target detection technique in homogeneous and nonhomogeneous environments

Abstract

The excision CFAR processor has been proposed for the detection of signals in an interference saturated environment, where such an environment is frequently encountered in radar applications (multiple target situations). The excision operation ensures that the calculation of the detection threshold is based on a set of samples which is purged of strong interferers and is therefore much more representative of the noise level. Since the frequency diversity between noncoherent pulse bursts is prevalent in radar detection systems, the performance evaluation of the excision CFAR detector with noncoherent integration is needed. Our goal in this paper is to analyze the performance of this type of CFAR radar target detection techniques when the radar receiver contains a noncoherent integrator amongst its basic elements. A chi-square family of fluctuating targets with an integer fluctuation parameter is employed as a model for the received signal. Our numerical results are focused on the important Swerling case II model because of the prevalence of frequency diversity between noncoherent pulse bursts. The processor performance is evaluated for the case where the background environment is assumed to be ideal (homogeneous) as well as in the presence of clutter power transitions and interfering targets amongst the contents of the reference window. It is found that the processor detectability loss, in homogeneous background, is very low and that the performance degradation, caused by interferers is quite small even if the number of the outlying targets is large. As the number of noncoherently integrated pulses increases, lower threshold values and consequently better detection performances are obtained, given that the excision threshold is held constant.