空间光通信的时间平滑实验研究

为了给空间光通信的瞄准捕获跟踪链路的设计提供参考,实验研究了强湍流区的大气闪烁时间平滑效应,并考虑大气闪烁和瞄准抖动误差,分析了空间光通信的跟瞄链路的强度起伏统计规律;在此基础上,分析了时间平滑对链路衰落起伏的改善作用.实验研究结果表明,随着曝光时间的增加,强湍流区的大气闪烁起伏幅度减小,当曝光时间达到几十毫秒时,强湍流区的大气闪烁起伏服从对数正态分布;在确保空间光通信系统的链路跟踪中断概率小于10-3以下,采用时间平滑可以使所需的衰落冗余减少15dB～20dB.

Experimental research of time-averaging effect in space optical communication

To present preference to design of pointing,acquisition and tracking link in space optical communication,time-averaging effect of the atmospheric scintillation in the strong turbulent regime was studied experimentally.The mathematical model for the fade probability in space optical communications was provided in which effect of the pointing jitter and atmospheric scintillation on intensity fluctuations was taken into account.Based on the above,the improvement of links' fade fluctuation by time-averaging effects was analyzed.Experimental results show that the probability density function of irradiance in the strong turbulent regime is governed by the lognormal distribution,when exposure time reaches several decades of milliseconds;the required fade budget of the link at a lost-tracking probability of 10-3 is improved by the least of 15dB~20dB,when the method of time-averaging effects of the atmospheric scintillation is used in space optical communications.