正交相干检波的误差分析

Error Analysis of the Quadrature Coherent Detection

正交相干检波器输出的同相分量和正交分量之间的幅度并非完全相等，相位并非完全正交，通常存在幅度和相位误差。该文首先推导了相干检波器输出的信号表达式，然后在假定误差由中频信号分裂和本振信号90°移相产生的条件下，给出了正交检波器输出的误差信号表达式，并分析了误差功率及其频谱特性，得到了幅度和相位误差与输出信号信噪比的关系式，最后给出了微机仿真结果。

The magnitude between the in-place channel and quadrature channel at the output of quadrature coherent detectors is not identical and the relative phase difference between the two channels is not just 9O°. Consequently,there exist gain and phase errors between the in-place channel and quadrature channel. Firstly,the output signal expression of the quadrature coherent detection is derived in this paPer. Then the error signal expression is given on condition that the errors are caused by the IF signal splitter and the 9o' phase shift. Then the error signal power and spectrum are analyzed and the relationship between the gain and phase error and the signal-nosie ratio of the output signal is obtained. Finally,the simulation results of the computer are given.