利用DORIS测轨系统实现高精度定轨

High Accuracy Orbit Determination with DORIS System

仿真研究DORIS测轨系统,重点考察了大气密度模型误差、测量精度、测轨网分布对定轨精度的影响。仿真结果表明,除了测轨网的地理分布,动力学模型中的大气模型误差对中低轨卫星精密定轨结果影响也较大。对ENVISAT卫星的DORIS实测数据进行了定轨分析,结果表明实测数据的定轨精度比仿真精度大约低1个量级不到。综合仿真结果和实测数据进行精度分析,推断对800km高度的太阳卫星轨道,采用8个DORIS信标站布设,24h定轨,定轨三维位置精度可以达到29cm(1σ),其中径向误差为3.4cm(1σ)。若采用30个DORIS信标站布设,定轨精度可提高30%。

DORIS system is based on accurate measurements of Doppler shifts,which are usually processed as range-rate data and the accuracy is better than 0.5mm/sec.To investigate the orbit determination accuracy through processing of DORIS data,this paper uses a set of simulation experiments to analyze various error sources,such as distribution of the ground-based beacons,observation error and atmospheric density model error,which may affect the accuracy.The results indicate that wider distribution of ground-based beacons brings better orbital accuracy.At the same time,atmospheric density model significantly reduces orbital accuracy.Furthermore,a comparison is made between simulation tests and actual data processing.From the comparison,we come to the conclusion that the accuracy of the position can be better than 30 cm(1σ) under the distribution of eight ground-based beacons using twenty-four hours Doppler range-rate data to determine a sun synchronous polar orbit at an altitude of 800km,and the result can be better than 20 cm(1σ) for global distribution of thirty ground-based beacons.