多相滤波法实现的数字正交相干检波器

正交相干检波可以保留信号包络的所有信息，因而在信号处理领域中有广泛的应用。传统的正交相干检波器由模拟器件构成，存在较大的镜频误差。该文介绍了一种由多相滤波法实现的数字正交相干检波器，并与其它常见的数字正交相干检方案进行了比较。计算机仿真结果表明，多相滤波法能够以较低的滤波器阶数达到较高的镜频抑制比，是目前较为理想的数字正交相干检波方案。

The Digital Quadrature Coherent Detector with the Polyphase Filter

The quadrature coherent detector is widely used in the field of signal processing since it can reserve all information about the complex envelope of IF signal. When it is realized by using the analog devices, the conventional quadrature coherent detector may result in the large image frequency errors. This paper described a digital quadrature coherent detector implemented with the polyphase filter, which the coefficients of in phase and quadrature branches were derived from the same low pass filter. The performances of four digital quadrature coherent detectors were compared. The computer simulation results showed that the digital quadrature coherent detector based on the polyphase filter had the higher suppress ratio of the image frequency component than other ones under the condition of the same orders of filters, and was an ideal digital quadrature coherent detector.