1.引言精确地分析存在噪声时二阶锁相环的性能目前仍是然数学难题,所以相位相关通讯系统的设计多半还要依据线性或准线性锁相理论。然而,在空间通讯方面,一些耗费巨资的特殊任务需要应用精确的非线性锁相环理论。而这一理论应能用于在发射前预示直到任务结束时止的通信系统的性能。近几年来,已有了几种分析存在噪声时锁相环性能的方法。本文不详述锁相理论的历史与演变,有兴趣的读者可参阅参考文献。但总而言之,迄今为 1. INTRODUCTION Precisely analyzing the performance of second-order phase-locked loop in the presence of noise is still a mathematical problem at present. Therefore, the design of phase-related communication system depends mostly on the linear or quasi-linear phase-locked theory. However, in space communications, some special tasks that cost a lot of money require the application of accurate nonlinear phase-locked loop theory. This theory should be used to predict the performance of the communications system until the end of the mission before launch. In recent years, several methods have been developed to analyze the performance of phase-locked loops in the presence of noise. This article does not elaborate on the history and evolution of phase-locked theory. Interested readers can refer to the references. But in a word, so far