表2.3中各种RCS模型的一个基本区别是概率密度函数是否包含一个或两个自由参数。

One fundamentaldifference among the various RCS models of Table 2.3 is whether the probabilitydensity function has one or two free parameters.

非波动分布、指数分布和所有的chi-square分布（阶数已确定）都是只有一个自由参数的分布模型。

The nonfluctuating,exponential, and all chi-square (once the order is stated) are allone-parameter distributions.

对于单参数分布，估计平均值足以描述完整的PDF。

For a one-parameterdistribution, estimating the mean is sufficient to characterize the completePDF.

对于两个参数的双参数情况，通常必须计算方差和均值或中值，用以描述PDF。

For the two-parametercase estimates of two parameters, usually the variance and either the mean ormedian, must be computed to characterize the PDF.

这种单参数和双参数的区别在第6章自动检测算法的设计中很重要。

This distinction isimportant in the design of automatic detection algorithms in Chap. 6.

大多数雷达分析和测量程序都强调RCS的测量，它与接收功率成正比。

Most radar analysisand measurement programs emphasize RCS measurements, which are proportional toreceived power.

有时候相应的接收回波电压ζ是大家感兴趣的，特别是用式（2.50）准确模拟多个散射体目标复合回波的仿真。

Sometimes ζ, thecorresponding voltage, is of interest, particularly for use in simulationswhere Eq. (2.50) is used explicitly to model the composite echo from a multiplescatterer target.

然后需要电压的概率密度函数，以便正确地模拟复电压和的概率变化。

The probabilitydensity function for the voltage is then required in order to properly modelthe probabilistic variations of the complex sum.

采用随机变量的基本结论，很容易根据σ的PDF推导出|ζ|的PDF。

The PDF of |ζ| iseasily derived from the PDF of σ using basic results of random variables(Papoulis and Pillai, 2001).

根据表2.3中的内容，式（2.55）可用于计算出电压的PDF。

Equation (2.55) canbe used to write the voltage PDFs by inspection from Table 2.3.

表2.4给出的结果是用表2.3中相应RCS分布参数予以表示的。

The results, given inTable 2.4, are expressed in terms of the parameters of the corresponding RCSdistribution from Table 2.3.

——本文译自Mark A. Richards所著的《Fundamentals of Radar Signal Processing（Second edition）》

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