星间光通信系统的捕获、瞄准及跟踪(APT)过程构成了一个切换系统,通过电荷藕合器件(CCD)采集的光斑信息决定了切换的序列以及激活的子系统,对通信连续性有重要影响。分析了光通信中的捕获、瞄准及跟踪过程,建立了系统的切换模型;根据所得的系统模型验证了由于光斑噪声引起的系统切换对通信链路的影响;并提出了将均值滤波、最大类间方差法和连通区域选择法结合对光斑噪声信号进行抑制的算法。仿真结果表明CCD采集得到的灰度图像通过该算法处理后,能有效地消除椒盐噪声、高斯噪声以及恒星背景噪声的影响,确保星间光通信过程的连续性。 The acquisition, aiming and tracking (APT) process of an intersatellite optical communication system constitutes a switching system. The spot information collected by a charge-coupled device (CCD) determines the sequence of switching as well as the active subsystems that are important to the continuity of the communication influences. The process of capture, aiming and tracking in optical communication is analyzed, and the system switching model is established. The system model is used to verify the influence of system switching on the communication link caused by speckle noise. Inter-variance method and connected region selection method combined with the spot noise signal suppression algorithm. The simulation results show that the grayscale image acquired by CCD can effectively eliminate the effects of salt and pepper noise, Gaussian noise and stellar background noise, and ensure the continuity of the inter-satellite optical communication process.