这些主题的讨论将体现在后面的每个章节中。
Each of these topics are discussed in thechapters that follow.
雷达信号处理利用了其它信号处理领域中使用的许多相同的技术和概念，这些技术来自与通信、声纳等密切相关的语音和图像处理领域。
Radar signal processing draws on many ofthe same techniques and concepts used in other signal processing areas, fromsuch closely related fields as communications and sonar to very differentapplications such as speech and image processing.
线性滤波和统计检测理论是雷达目标检测中最基本的知识。
Linear filtering and statistical detectiontheory are central to radar’s most fundamental task of target detection.
使用快速傅立叶变换(FFT)技术实现的傅立叶变换处理无处不在，用于从匹配滤波器的快速卷积实现、多普勒谱估计到雷达成像等各个方面。
Fourier transforms, implemented using fastFourier transform (FFT) techniques, are ubiquitous, being used for everythingfrom fast convolution implementations of matched filters, to Doppler spectrumestimation, to radar imaging.
现代的基于模型的谱估计和自适应滤波技术已经被用于波束形成和干扰消除。
Modern model-based spectral estimation andadaptive filtering techniques are used for beamforming and jammer cancellation.
模式识别技术用于目标/杂波辨识和目标识别。
Pattern recognition techniques are used fortarget/clutter discrimination and target identification.
同时，与其它信号处理领域相比，雷达信号处理具有若干独特的特性。
At the same time, radar signal processinghas several unique qualities that differentiate it from most other signalprocessing fields.
大多数现代雷达是相干的，这意味着接收信号解调到基带后的输出是复值而不是实值。
Most modern radars are coherent, meaningthat the received signal, once demodulated to baseband, is complex-valuedrather than real-valued.
雷达信号具有很高的动态范围，一般能达到几十分贝，在一些特殊情况下接近100分贝。
Radar signals have very high dynamic rangesof several tens of decibels, in some extreme cases approaching 100 dB.
因此，增益控制设计是很常见的，旁瓣控制也至关重要的，以避免强信号将弱信号掩盖遮蔽。
Thus, gain control schemes are common, andsidelobe control is often critical to avoid having weak signals masked bystronger ones.
通常情况下的SIR比值相对较低。
SIR ratios are often relatively low.
例如，检测时的SIR可能只有10到20dB，而信号处理之前的单个接收脉冲的SIR通常小于0dB。
For example, the SIR at the point ofdetection may be only 10 to 20 dB, while the SIR for a single received pulseprior to signal processing is frequently less than 0 dB.
尤其重要的是，与大多数其它的数字信号处理应用相比，雷达信号的带宽较大。
Especially important is the fact that,compared to most other DSP applications, radar signal bandwidths are large.
单个脉冲的瞬时带宽通常为几兆赫，在一些高分辨率雷达中可能达到几百兆赫，甚至高达1GHz。
Instantaneous bandwidths for an individualpulse are frequently on the order of a few megahertz, and in some fineresolution radars may reach several hundred megahertz and even as high as 1GHz.
这一事实对于数字信号处理具有若干意义。
This fact has several implications fordigital signal processing.
例如，高带宽雷达信号的处理需要速度非常快的模数（A/D）转换器。
For example, very fast analog-to-digital(A/D) converters are required.
历史上，由于多兆赫A/D转换器的设计困难，直接影响到数字技术引入到雷达信号处理中的应用速度。
The difficulty of designing good convertersat multi-megahertz sample rates has historically slowed the introduction ofdigital techniques into radar signal processing.
即使是现在，数字技术已经在新的设计中非常常见，而高带宽系统中的雷达采样位数通常相对较短，只有8到12位，而不是在许多其它领域中常见的16位。
Even now, when digital techniques arecommon in new designs, radar word lengths in high-bandwidth systems are usuallya relatively short 8 to 12 bits, rather than the 16 bits common in many otherareas.
在历史上，高数据速率也意味着常常需要为数字处理器设计定制的硬件，以便获得足够的吞吐量，即“跟上”数据的采集速度。（也就是说，你的“吃饭”速度要与肠胃的“消化”速度相匹配，如果吃饭吃得快（采样率太高），而肠胃消化太慢，则无法有效吸收消化，就会导致浪费或者发生疾病）
The high data rates have also historicallymeant that it has often been necessary to design custom hardware for thedigital processor in order to obtain adequate throughput, that is, to"keep up with" the onslaught of data.
与声呐处理技术相比，吞吐量不足的问题导致雷达信号处理算法只能相对简单，否则处理不过来。
This same problem of providing adequatethroughput has resulted in radar signal processing algorithms being relativelysimple compared to, say, sonar processing techniques.
——本文译自Mark A. Richards所著的《Fundamentals of Radar Signal Processing（Second edition）》
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