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雷达接收机中的相干检波器一般都是以基带正交通道的形式实现的,以便降低所需要的A/D变换器的采样率。其相位精度取决于两个正交通道的调整,它限制了雷达信号处理器所能达到的性能。现代A/D变换器的速度已经很快,足以在载频大于信号带宽的中频点直接对信号进行采样。应用大家熟知的“窄带”信号采样和处理的定律,能够节省硬件和改善性能。本文回顾有关的理论并说明中频采样的线性滤波所需要的处理方法。给出的一些例子说明,不用把信号分解成I、Q分量就可以完成脉冲压缩。最后给出一个附录,说明用实验室硬件和数字式I/Q检波器进行的中频采样所能达到的固有相位精度。
Coherent detectors in radar receivers are generally implemented in the form of baseband orthogonal channels in order to reduce the required sample rate of the A / D converter. The phase accuracy depends on the adjustment of two orthogonal channels, which limits the radar signal processor can achieve the performance. Modern A / D converters are fast enough to sample the signal directly at mid-frequency points where the carrier frequency is greater than the signal bandwidth. Applying the well-known law of “narrowband” signal sampling and processing, you save hardware and improve performance. This article reviews the theory and illustrates the processing required for linear filtering of IF samples. Some examples are given to show that pulse compression can be done without breaking down the signal into I and Q components. Finally, an appendix shows the inherent phase accuracy achievable with IF sampling using lab hardware and a digital I / Q detector.