还可以用于“地形跟随”导航，将测量图像与存储的地图相互关联起来。
They can also be used for “terrainfollowing” navigation by correlating measured imagery with stored maps.
虽然雷达图像还没有达到光学图像的分辨率，但是微波频率下电磁波的低衰减特性使得雷达具有“透视”云层、雾和雨水的重要优势。（即雷达具有全天候的监视能力，受气象因素影响很小，但是雷达图像的分辨力远低于光学图像。）
While radar images have not achieved theresolution of optical images, the very low attenuation of electromagnetic wavesat microwave frequencies gives radar the important advantage of"seeing" through clouds, fog, and precipitation very well.
因此，当光学仪器完全无法使用时，成像雷达能够产生有用的图像。（因此二者是互补的！）
Consequently, imaging radars generateuseful imagery when optical instruments cannot be used at all.
根据所需要的功能，雷达系统的性能可以通过各种指标进行衡量。
The quality of a radar system is quantifiedwith a variety of figures of merit, depending on the function being considered.
在分析雷达的目标检测性能时，最基本的参数是检测概率PD和虚警概率PFA。
In analyzing detection performance, thefundamental parameters are the probability of detection PD and theprobability of false alarm PFA.
如果雷达的其它系统参数固定，那么增大检测概率PD的同时，也会导致虚警概率PFA的增大。
If other system parameters are fixed,increasing PD always requires accepting a higher PFA aswell.
检测和虚警概率的组合由信号和干扰统计特性决定，尤其是信干比SIR。
The achievable combinations are determinedby the signal and interference statistics, especially the signal-tointerferenceratio (SIR).
当雷达探测波束中存在多个目标时，在评估目标检测性能时需要考虑雷达系统的分辨率和旁瓣。
When multiple targets are present in theradar field of view, additional considerations of resolution and sidelobesarise in evaluating detection performance.
例如，如果两个目标不能够被雷达分辨，那么它们将被认为是同一个目标。
For example, if two targets cannot beresolved by a radar, they will be registered as a single object.
如果旁瓣很高，来自强反射点的目标回波可能掩盖来自附近但较弱目标的回波，因此仍然会将两个目标判断为只有一个目标存在。
If sidelobes are high, the echo from onestrongly reflecting target may mask the echo from a nearby but weaker target,so that again only one target is registered when two are present.
距离上的分辨率和旁瓣由雷达波形决定，而角度上的分辨率和旁瓣由天线方向图决定。
Resolution and sidelobes in range aredetermined by the radar waveform, while those in angle are determined by theantenna pattern.
在雷达跟踪中，最基本的指标是距离、角度和速度估计精度。
In radar tracking, the basic figure ofmerit is accuracy of range, angle, and velocity estimation.
虽然分辨率对精度提出了粗略的限制，但是通过适当的信号处理，最终可实现的精度在每种情况下都受到SIR的限制。
While resolution presents a crude limit onaccuracy, with appropriate signal processing the achievable accuracy isultimately limited in each case by the SIR.
在成像雷达中，主要的指标是空间分辨率和动态范围。
In imaging, the principal figures of meritare spatial resolution and dynamic range.
空间分辨率决定了在最终图像中可以识别出多大尺寸的目标，因此也决定了该图像的用途。
Spatial resolution determines what sizeobjects can be identified in the final image, and therefore to what uses theimage can be put.
例如，分辨率为1km x 1km的雷达图像对于土地利用研究是有用的，但对于机场或导弹场地的军事监视是没有用的。
For example, a radar map with 1 km by 1 km resolution would be useful for land use studies, but uselessfor military surveillance of airfields or missile sites.
动态范围决定了图像对比度，这也有助于从图像中提取出更多的信息量。
Dynamic range determines image contrast,which also contributes to the amount of information that can be extracted froman image.
雷达信号处理的目的就是要提高以上这些性能指标。
The purpose of signal processing in radaris to improve these figures of merit.
SIR可以通过脉冲积累得到改善。
SIR can be improved by pulse integration.
通过脉冲压缩和其它波形设计技术，例如频率捷变，可以联合提高分辨率和SIR。
Resolution and SIR can be jointly improvedby pulse compression and other waveform design techniques, such as frequencyagility.
测量精度得益于SIR的增大，也可以使用插值方法提高精度。
Accuracy benefits from increased SIR andinterpolation methods.
几乎在信号处理的所有应用中都使用类似的加窗技术，这样可以改善旁瓣特性。
Sidelobe behavior can be improved with thesame windowing techniques used in virtually every application of signalprocessing.
——本文译自Mark A. Richards所著的《Fundamentals of Radar Signal Processing（Second edition）》
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