在恒虚警条件下滤波及非理想门限对游程检测性能的影响

The Influence of Filtering and Non-ideal Threshold to Run Length Detecting Property under CFAR

在许多检测系统中不仅采取门限比较,而且还采取用过门限的宽度(即要求连续多个检测值过门限)来判定目标出现的检测方法——游程检测[1],这种检测方法通常会得到比仅进行门限检测更好的检测性能。但是在恒虚警条件下,滤波、或门限特性不理想对游程检测特性影响的理论分析难度较大,在此我们通过仿真计算得出:当门限过渡区Δd和噪声方差值接近时,游程检测性能大大下降,因此为了得到较好的检测特性,应将Δd控制在不超过噪声方差0.7倍的范围内;在游程检测中不宜加低通滤波而应采用高通滤波;可以在门限d1=0时以满足虚警率要求的游程作为检测游程N1等结论,为系统设计提供一些参考。

Many detection systems apply not only threshold comparison, but also the passing threshold width （successive signal values pass the threshold ） to determine target appearance This method, the method of run length detecting, can usually obtain a better detecting property than the method of threshold detecting. But,under the condition of CFAR （constant false alarm rate） ,it is difficult to do theoretical analysis on the influence of filtering and non-ideal threshold to the run length detecting property. The simulated computing result shows： when the transition region △d is close to the noise variance value,the run length detecting property will sharply drop down. In order to get better detecting property, the measures and conclusions below are applied and testified： △d should be confined to 0. 7 times more than the noise valance; high pass filters should rather be used than to low pass filters in the run length detecting system;when threshold d1 = 0 ,the run length,which meets CFAR demands,can be taken as the detecting run length N1 .