中文摘要：

为了保证光通信终端的精确对准，抑制编码器莫尔条纹正弦性偏差引入的细分误差，设计了基于经验模态分解（empir—icalmodedecomposition，EMD）的正弦性修正方法。首先，介绍了卫星光通信终端跟瞄系统的组成与工作原理。接着，分析了莫尔条纹正弦偏差给系统带来的细分误差并给出满足工程需求的正弦性阈值。然后，在阐述EMD分解原理的基础上，给出了基于EMD的正弦性修正方法，该方法利用编码器自身粗码信息计算转速，从而确定精码莫尔条纹信号的基波频率值，并采用EMD分解在原始信号中提取与该值相匹配的基波分量。最后，对该方法进行了原理和转速自适应性仿真，并应用到去掉光学滤波镜片后的粗瞄回路编码器中。仿真及实验结果表明：在光通信终端的各工作转速下，修正后的莫尔条纹正弦性均小于0．85％，满足细分要求；修正后的精码译码结果精确，编码器测角精度维持在1”以内，满足终端对准精度的要求。

英文摘要：

In order to ensure that optical communication terminal points at target precisely, a method is put forward to compensate the sinusoidal deviation of Moir6 fringe in photoelectrical encoder, which is the position sensor of the coarse pointing system. First, the structure and operational principle of the satellite optical communication terminal are introduced. Then the subdividing error of the encoder caused by sinusoidal deviation is analyzed, and the thresh old of sinusoidal deviation that could satisfy engineering needs is given. Based on the principle of empirical mode de composition （EMD） , a compensating algorithm is put forward, in which the fundamental frequency of moir6 fringe is decided according to the rotating speed calculated by the coarse coder. With empirical mode decomposition, the fun damental wave component is extracted. Simulation results indicate that this method works well at different rotating speeds. When the method is applied in a photoelectrical encoder in which the optical filtering lens is removed, the experiment result shows that the sinusoidal deviations are less than 0.85% at different speeds, the precision of the encoder maintains in 1＂, and the encoder can satisfy the need of pointing precision.