图1.15说明了一个简单的单频脉冲在距离维度上的分辨率和分辨率间隔。

Figure 1.15 illustrates resolution and theresolution interval in the range dimension for a simple constant-frequencypulse.

Figure 1.15. 用于描述常规脉冲距离分辨率的几何关系示意图Geometry for describing conventional pulse range resolution.

如果持续时间为τ秒的脉冲信号前沿位于t = 0时刻，那么如图所示，t₀时刻从散射体返回的脉冲回波前沿将在距离ct₀/2处接收到。

If a pulse whose leading edge istransmitted at time t = 0 has duration τ seconds, then at time t₀the echo of the leading edge of the pulse will be received from a scatterer atrange ct₀/2.

同时，返回的脉冲回波后沿在距离c(t₀ – τ)/2处接收到。

At the same time, echoes of the trailingedge of the pulse from a scatterer at range c(t₀ – τ)/2 are alsoreceived.

任何位于脉冲前沿和后沿之间的散射体也会对回波电压的大小产生影响。

Any scatterers at intermediate ranges wouldalso contribute to the voltage at time t₀ .

因此，分布在cτ/2距离范围内的散射体都会同时对接收电压作出贡献。

Thus, scatterers distributed over cτ/2 in range contribute simultaneously to thereceived voltage.

为了能够将两个散射体的贡献分离为不同的时间采样样本，它们之间的间隔必须大于cτ/2米，以使得它们各自的回波不会在时间上重叠。

In order to resolve the contributions fromtwo scatterers into different time samples, they must be spaced by more thancτ/2 meters so that their individual echoes do not overlap in time.

cτ/2被称为距离分辨率ΔR。

The quantity cτ/2 is called the rangeresolution ΔR.

类似地，二维和三维分辨率单元可以通过考虑距离、方位角和俯仰角中的同时分辨率来定义。

Similarly, two- and three-dimensionalresolution cells can be defined by considering the simultaneous resolution in,say, range, azimuth angle, and elevation angle.

注意：这种距离分辨率的描述仅适用于未调制的单频脉冲。

This description of range resolutionapplies only to unmodulated, constant frequency pulses.

正如第四章中看到的，脉冲调制结合匹配滤波可用于获得比cτ/2更精细的距离分辨率。

As will be seen in Chap. 4, pulsemodulation combined with matched filtering can be used to obtain rangeresolution finer than cτ/2.

方位和俯仰维的角分辨率由同一平面中的天线波束宽度决定。

Angular resolution in the azimuth andelevation dimensions is determined by the antenna beamwidths in the sameplanes.

如果两个散射体位于天线主瓣内，并且因此被同时照射，那么这两个在相同距离但不同方位角(或俯仰角)的散射体将同时对接收的回波信号做出贡献。

Two scatterers at the same range butdifferent azimuth (or elevation) angles will contribute simultaneously to thereceived signal if they are within the antenna mainlobe and thus are bothilluminated at the same time.

为了估计角分辨率，通常将主瓣宽度取为天线的3dB波束宽度θ。

For the purpose of estimating angularresolution, the mainlobe width is typically taken to be the 3-dB beamwidth θ ofthe antenna.

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

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