空间光通信中轨道短时预报

Satellite Orbit Forecast in Short Time for Free Optical Communication

瞄准、捕获和跟踪(PAT)技术是星间光通信的关键技术之一,高精度卫星轨道短时预报能有效实现PAT。首先在EGM96地球引力场模型下建立了卫星状态动力方程和预报方程,然后改进基于数值算法的扩展卡尔曼滤波算法对卫星轨道短时预报,最后以champ卫星星载GPS实时定轨数据为卡尔曼滤波器观测数据进行仿真实验:预报卫星位置误差约亚米级,速度误差约0.05m/s;卫星位置和速度的均方差估计趋于稳定,在一定程度上能很好地克服离散误差和模型误差对轨道估计精度的影响。PAT瞄准精度约1.6μrad,预报轨道精度能满足空间光通信PAT技术要求。

PAT（Pointing,Acquisition,Tracking） has become the key technology of inter- satellite optical communication. High accuracy satellite orbit forecast in short time can realize PAT effectively. This paper first presented the state space equations and forecast equations based on the reference gravity field models EGM96. and an extended Kalman Filtering（EKF） for forecasting satellite orbit was presented based on advanced numerical arithmetic. The real time orbit determination of on - board GPS receivers was used as observation data of EKF. It was confirmed by simulation that the precision of forecasting satellite position is approximate to sub - meter level, and precision of forecasting satellite speed is approximate to 0.05m/s. It was also confirmed that the mean square error of forecasting sat- ellite position and speed becomes stable, thus overcoming the influences of discrete error and model error to some extent. Precision of pointing is about 1.61μrad, so the accuracy of forecasting satellite orbit meet the requirement of PAT technology of free optical communication.