空时自适应滤波（STAP）结合角度和多普勒域的自适应波束形成，同时实现杂波和干扰的抑制。

Space-time adaptive filtering (STAP)combines adaptive beamforming in both angle and Doppler for simultaneoussuppression of clutter and jammer interference.

图1.20说明了使用STAP进行干扰抑制的方法，从而允许检测到以前不可检测的目标信号。

Figure 1.20 illustrates interferencesuppression using STAP, allowing a previously invisible target signal to beseen and perhaps detected.

Figure 1.20. 自适应波束形成效果的示例。(a)接收信号功率作为到达角和信号多普勒频移的函数映射。(b)自适应处理后的角度-多普勒二维图。Example of effect of adaptivebeamforming. (a) Map of received signal power as a function of angle of arrivaland signal Doppler shift. (b) Angle-Doppler map after adaptive processing.(Images courtesy of Dr. W. L. Melvin. Used with permission.)

图1.20a中的两条垂直条带表示来自固定到达角的干扰能量，通常以相对宽带的噪声形式出现，因此干扰存在于雷达观测到的所有多普勒频率中。

The two vertical bands in Fig. 1.20a represent jammer energy, whichcomes from a fixed angle of arrival but is usually in the form of relativelywideband noise; thus it is present at all Doppler frequencies observed by theradar.

图1.20a中的对角线条带是由于地杂波引起的，因此多普勒频移取决于从雷达到地面分块的角度。

The diagonal band in Fig. 1.20a is due to ground clutter, for whichthe Doppler shift depends on the angle from the radar to the ground patchcontributing energy.

图1.20b表明，自适应滤波已经沿着干扰和杂波能量的条带区域产生零点，从而使得位于0°到达角和400Hz多普勒频移的目标凸现出来。

Figure 1.20b shows that the adaptivefiltering has created nulls along the loci of the jammer and clutter energy,making the target at 0° angle of arrival and 400 Hz Doppler shift apparent.

自适应干扰抑制将在第九章中予以介绍。

Adaptive interference suppression will beintroduced in Chap. 9.

脉冲压缩是匹配滤波的一种特殊情况。

Pulse compression is a special case ofmatched filtering.

许多雷达系统设计都力求在检测目标时具有高灵敏度和良好的距离分辨率（分辨相邻距离很近的目标的能力）。

Many radar system designs strive for bothhigh sensitivity in detecting targets and fine range resolution (the ability todistinguish closely spaced targets).

接下来的章节表明，随着发射能量的增加，目标可检测性能提高，并且随着发射波形的瞬时带宽增加，距离分辨率提高。

Upcoming chapters show that targetdetectability improves as the transmitted energy increases, and that rangeresolution improves as the transmitted waveform's instantaneous bandwidthincreases.

如果雷达采用简单的、恒定频率的矩形包络脉冲作为发射波形，则脉冲必须在时域加长以提高给定功率电平的发射能量。

If the radar employs a simple,constant-frequency rectangular envelope pulse as its transmitted waveform thepulse must be lengthened to increase the transmitted energy for a given powerlevel.

然而，脉冲宽度的增大也降低了其瞬时带宽，从而降低了距离分辨率。

However, lengthening the pulse alsodecreases its instantaneous bandwidth, degrading the range resolution.

因此，灵敏度和距离分辨率之间似乎发生了相互冲突。

Thus sensitivity and range resolutionappear to be in conflict with one another.

通过将波形带宽与其持续时间解耦，脉冲压缩提供了一种摆脱这种困境的方法，从而避免了灵敏度和距离分辨率之间的冲突。

Pulse compression provides a way out ofthis dilemma by decoupling the waveform bandwidth from its duration, thusallowing both to be independently specified.

这是通过放弃恒频脉冲而设计调制波形来实现的。

This is done by abandoning theconstant-frequency pulse and instead designing a modulated waveform.

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

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