这种效应也可以从相反的方向来看待：如果信号在频域变得更宽，那么它在时域必须变得更窄。

This effect can also be viewed in theopposite direction: if the signal gets wider in the frequency domain, it mustget narrower in the time domain.

将傅里叶变换的互易扩展特性与分辨率取决于信号宽度的观测相结合，表明提高时域分辨率需要在相反的傅里叶频域中增加“带宽”。

Combining the reciprocal spreading propertyof Fourier transforms with the observation that resolution depends on signalwidth shows that improving resolution requires increasing "bandwidth"in the opposite Fourier domain.

例如，提高简单脉冲的距离分辨率需要使用更短的脉冲，如第1.4.2节所示；但是图1.17表明，较短的脉冲意味着较宽的频谱，即更大的带宽。

For example, improving range resolution forsimple pulses requires using shorter pulses, as was seen in Sec. 1.4.2;but Fig. 1.17 shows that a shorter pulse implies a wider spectrum, i.e., morebandwidth.

相反，第1.4.2节表明，频域分辨力的提高需要更窄的频谱主瓣宽度，根据图1.17，则需要在时域观测更长的时间。

Conversely, it was also shown in Sec. 1.4.2that improving resolution in the frequency domain requires a narrower spectrummainlobe and thus according to Fig. 1.17, a longer observation (more"bandwidth") in the time domain.

以上现象适用于任何两个与傅里叶变换相关的函数：在一个域中更精细的分辨率要求在其相反域中更多的信息支持。

This behavior holds for any two functionsrelated by a Fourier transform: finer resolution in one domain requires widersupport in the opposite domain.

雷达设计人员已经开发了增加适当带宽的技术，以在各种维度上获得改进的分辨率。

Radar designers have developed techniquesfor increasing the appropriate bandwidth to obtain improved resolution invarious dimensions.

例如，提高距离分辨率需要增加波形带宽，这就导致使用宽带相位和频率调制波形来代替简单的脉冲波形（第四章）。

For example, improving resolution in rangerequires increasing waveform bandwidth, which has led to the use of widebandphase- and frequency-modulated waveforms in place of the simple pulse (Chap.4).

提高横向距离分辨率需要在较宽角度范围内持续观测场景，以增大横向空间频率带宽，这就是第8章讨论的合成孔径技术。

Improving cross-range resolution requiresviewing a scene over a wide angular interval to increase cross-range spatialfrequency bandwidth, and leads to the synthetic aperture techniques of Chap. 8.

提高速度（即，多普勒）分辨率需要长时间的观测数据，并采用多脉冲波形完成。

Improving velocity (equivalently, Doppler)resolution requires a long time observation and is accomplished with multipulsewaveforms.

由于天线远场方向图是孔径电流分布的傅里叶变换，因此采用较大的孔径（即较大的天线）可以获得改进的角分辨率。

Because the antenna far-field pattern isthe Fourier transform of the aperture current distribution, improved angularresolution can be obtained with larger apertures, i.e., bigger antennas.

1.5 基本雷达信号处理综述

1.5. A Preview of Basic Radar SignalProcessing

在雷达信号处理的早期阶段，组件的设计是由后期的一些组件特性驱动的，这样的情况有很多。

There are a number of instances where thedesign of a component early in the radar signal processing chain is driven byproperties of some later component.

例如，在第4章，可以看到匹配滤波器使信噪比最大化；但是直到推导出匹配滤波器的检测器性能曲线，才会看到最大化信噪比也优化了检测性能。

For example, in Chap. 4 it will be seenthat the matched filter maximizes SNR; but it is not until the performancecurves for the detectors that follow the matched filter are derived that itwill be seen that maximizing SNR also optimizes detection performance.

在考虑检测器之前，很难确切地看出雷达性能如何依赖于SNR。

Until the detector is considered, it ishard to see exactly how performance depends on SNR.

在介绍了典型脉冲相干雷达系统的主要组成部分之后，现在试探性地描述雷达信号处理链中最常见的信号处理操作。

Having seen the major components of atypical pulsed coherent radar system, the most common signal processingoperations in the radar signal processing chain are now describedheuristically.

通过从头到尾勾画的“宏观框图”的这个预览，可能更容易理解后面章节将要描述的许多处理操作的动机和相互关系。

By sketching out this preview of the"big picture" from beginning to end, it may be easier to understandthe motivation for and interrelation of many of the processing operations to bedescribed in later chapters.

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

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