Improved switching CFAR detector for non-homogeneous environments

Abstract

In order to mitigate the excessive false alarm rate of the switching constant false alarm rate (S-CFAR) detector at the clutter edge, an improved switching CFAR (IS-CFAR) detector is proposed in this paper. In IS-CFAR, a comparison threshold is generated by multiplying the amplitude of the test cell by a scaling factor. Then in the leading and lagging reference windows, the numbers of reference cells whose amplitudes are smaller than the comparison threshold are countered and compared with a threshold integer. Based on the comparison result, the detection threshold is generated by selecting appropriate reference cells for background noise/clutter power estimation. The detection probability of IS-CFAR in various environments is derived in a closed-form expression. The performance is evaluated and compared with other CFAR detectors. It is shown that IS-CFAR exhibits a low CFAR loss in a homogeneous environment and almost the same detection performance as S-CFAR in a multiple targets situation; at a clutter edge, the false alarm rate of IS-CFAR is much lower than that of S-CFAR and approximates to the greatest-of CFAR (GO-CFAR). Experimental results from a linear frequency modulated continuous wave (LFMCW) radar system are given to demonstrate the efficiency of IS-CFAR.