Study On Constant False Alarm Rate Detection Under Heterogeneous Background

Constant false alarm rate(CFAR)is one of the important research contents in modern radar signal processing,and it possesses a significant position in radar adaptive detection.In practice,radar usually works in heterogeneous clutter environment,so classical CFAR methods cannot maintain a good detection performance.Motivated by this,the problem of CFAR detection algorithms in complex environment is studied and a method to adaptively choose the CFAR algorithm that matches with the clutter background is proposed in this thesis.Firstly,the fundamentals of radar adaptive detection are introduced.Then,classical CFAR detection algorithms are studied,including the mean level CFAR algorithm and the order statistic type algorithm.Secondly,with regard to mean level CFAR algorithms,CA-CFAR,GO-CFAR,SO-CFAR and Log-CFAR algorithms are mainly studied.OS-CFAR,a typical order statistic type algorithm,is also discussed.The detection performance of each algorithm is analyzed in the homogeneous clutter,the clutter edge and the multiple targets cases.The CFAR loss under homogeneous background of each algorithm is compared and the suitable environment for each algorithm is summarized.Lastly,the clutter map CFAR has a good detection performance under the situation that the clutter varies drastically in the spatial domain and keeps stationary in the temporal domain.The clutter map CFAR proposed by Nitzberg and the logarithm clutter map CFAR are mainly studied.The detection performance of the two methods are analyzed and compared by simulation experiments.Furthermore,the estimation accuracy of the background power level and the target detection performance using the two methods are compared through the measured data processing results.According to the characteristics of the logarithm clutter map and the ML-CFAR algorithm,an adaptive CFAR algorithm based on the logarithm clutter map is proposed.The logarithm clutter map of detection area is established first.Then,the clutter environment surrounding the cell under test is distinguished according to the pre-established logarithm clutter map,including homogeneous clutter area,weak clutter area or heavy clutter area of clutter edge.Last,according to the clutter background of the cell under test,the proposed method adaptively chooses the most appreciate CFAR algorithm that matches with the present clutter background.The processing results show that the proposed method can reduce the false alarm rate and the missing alarm rate effectively in the clutter edge case,and improve the detection performance of radar in heterogeneous background.