粗糙目标光外差信号特性对探测阈值的影响

Effect of properties from a rough target echo signal on the detection threshold in optical heterodyne detection

传统目标回波光外差探测使用高斯分布等简单模型来描述,这常常导致判决误差.笔者提出利用多项式对实际目标测量数据进行拟合,给出较准确的概率分布曲线.通过对某装甲车表面样块多组测量数据的统计分析显示,利用多项式拟合来确定判决阈值,比起用简单的高斯分布来确定阈值,可以获得更高的检测概率和更低的误警概率.研究表明,对实测中频信号的统计直方图进行多项式拟合,有利于精确设置探测阈值,可以使检测概率提高6.02%,误警概率降低7.7%.文中结果为粗糙面回波外差探测系统设计提供定量参考,也为探测系统性能评估仿真提供依据.

Traditionally, a simple model, such as Gaussian distribution, describes the optical heterodyne detection echo signal of the target, which often leads to judgment errors. In this paper, we present a more accurate method to describe the probability distribution of the echo signal by use of polynomial fitting. The echo signals from a surface coating specimen of an armored car are measured, with the statistical analysis showing that the probability of detection is higher and the probability of false alarm is lower, when using the method of polynomial fitting to determine the decision threshold, rather than using a simple Gaussian distribution to determine it. The results show that by the method of polynomial fitting on the statistical histogram of the measured intermediate frequency signal, the precision of setting the detection threshold will be improved, and that the probability of detection rises by 6.02 % and the probability of false alarm fails by 7.7 %. The results of this paper provide a quantitative reference for designing the rough surface echo heterodyne detection system and also provide a useful tool for evaluating the performance of the heterodyne detection system.