1.4.3. 数据积累与相位变化建模

1.4.3. Data Integration and Phase History Modeling

在雷达信号处理中，一种最基本的操作就是对数据样本进行积累以提高信干比SIR。

A fundamental operation in radar signalprocessing is integration of samples to improve the SIR.

相干积累与非相干积累都是人们感兴趣的方法。

Both coherent integration and noncoherentintegration are of interest.

前者指复采样数据(即幅度和相位)的积累，而后者指仅基于数据的幅度(可能的平方或对数幅度)的积累。

The former refers tointegration of complex (i.e., magnitude and phase) data, while the latterrefers to integration based only on the magnitude (or possibly the squared orlog magnitude) of the data.

现在假设测量重复了N – 1次。

Now suppose the measurement is repeated N –1 more times.

人们期望重复测量相同的确定性回波响应，但是每次都使用独立的噪声样本。

One expects to measure the samedeterministic echo response, but with an independent noise sample each time.

通过将多次独立的测量结果进行积累（求和）形成单次测量数据，这种保留相位信息的处理就是相干积累：

Form a single measurement z by integrating(summing) the individual measurements; this sum of complex samples, retainingthe phase information, is a coherent integration:

对N次测量进行相干积累可以将信噪比提高N倍，这种信噪比的提高称为积累增益。

Coherently integrating N measurements hasimproved the SNR by a factor of N; this increase is called the integration gain.

以后的章节将表明，正如人们所期望的，增加信噪比可以提高检测和参数估计性能。

Later chapters show that, as one wouldexpect, increasing the SNR improves detection and parameter estimationperformance.

由此引入的代价是采集与处理N个脉冲数据的时间、能量和运算量。

The cost is the extra time, energy, andcomputation required to collect and combine the N pulses of data.

在相干积累中，这里的信号相位的累加，意味着“相干特性”。

In coherent integration, the signalcomponents added in phase, i.e., coherently.

通常将信号描述为基于电压的相加，因为积累的信号幅度增大了N倍，使得信号的功率增大了N²倍。

This is often described as adding on avoltage basis, since the amplitude of the integrated signal component increasedby a factor of N, with the result that signal power increased by N².

而噪声样本的相位变化是随机的，是基于功率的相加。

The noise samples, whose phases variedrandomly, added on a power basis.

正是因为信号分量相位的对齐使得信号功率比噪声功率增长得更快。

It is the alignment of the signal componentphases that allowed the signal power to grow faster than the noise power.

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

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