Wishart分布情形下极化SAR图像目标CFAR检测解析方法

等效视数是影响极化合成孔径雷达（PolSAR）图像恒虚警 （CFAR）检测性能的重要参数.目前等效视数的估计大都不是整数，导致已有的基于整数等效视数的CFAR检测方法不再适用.为解决此问题，提出了一种新的PolSAR图像目标CFAR检测解析算法.首先，在Wishart分布假设下，推导出了多视极化白化滤波（MPWF）检测量的概率密度函数；然后对其积分得到了CFAR检测门限关于等效视数的解析表达式；最后通过仿真数据和AIRSAR实测数据比较了新方法与已有的适用于整数等效视数的检测方法和双参数恒虚警（2P-CFAR）检测方法的CFAR检测性能.结果表明新方法中实际虚警概率与给定的恒虚警概率最为接近，更好保证了CFAR检测的恒虚警假设.

Polarimetric SAR Imagery Target CFAR Detection Analytical Algorithm with Wishart Distribution

The equivalent number of looks (ENL) is a key parameter that affects the constant false alarm rate (CFAR) detection performances in polarimetric synthetic aperture radar (PolSAR) imageries.At present,the estimated value of the ENL mostly is not an integer,resulting that existing CFAR detection algorithms are no longer applicable.To solve this problem,a new analytical CFAR algorithm of target detection is proposed in PolSAR imageries.Firstly,the probability density function (PDF) of multi-look polarimetric whitening filter (MPWF) metric is derived based on Wishart distribution assumption;Secondly,the analytical expression of CFAR detection threshold with respect to the ENL is obtained by integrating the PDF of MPWF metric;Finally,the CFAR detection performances of the new algorithm are compared with other CFAR detection algorithms via simulation data and AIRSAR measured data.The results show that the real false alarm probability in the new algorithm is the closest to the given constant false alarm probability,which better guarantees the hypothesis of the constant false alarm probability in the CFAR detection.