低轨卫星下行仿真数据精密定轨研究

Precision orbit determination research of LEO satellite simulated downlink data

低轨卫星导航定位是新一代卫星导航技术发展的重要方向,使用低轨卫星提供高精度定位、导航与授时(positioning,navigation and timing,PNT)服务,需要能够利用下行数据对其进行精密定轨.目前低轨卫星定轨相关研究多以星载GNSS数据和星间链路数据为研究对象,缺少针对低地球轨道(low earth orbit,LEO)下行数据定轨能力的分析.为分析低轨卫星下行数据定轨性能,模拟仿真了轨道高度1000 km、轨道倾角48°的Walker 90/10/1低轨卫星导航星座、150个地面测站及相应轨道、钟差和观测数据.分别使用测站数为60、90、120和150的全球测站网络观测数据进行LEO卫星精密定轨,并对定轨精度和可视测站卫星位置精度衰减因子(satellite position dilution of precision,SPDOP)值进行分析.结果表明:测站数从60增加至150可使LEO卫星轨道1d均方根(root mean square,RMS)从117.5 mm提升至39.8 mm;当测站稀疏时,LEO卫星定轨精度降低迅速;增加测站可以有效改善陆地范围可视测站SPDOP和LEO卫星定轨精度,但由于测站跟踪范围有限,海洋区域可视测站SPDOP和LEO卫星定轨精度难以获得改善,需引入新的观测数据源.研究结果可为低轨导航卫星系统建设提供支持.

This study focuses on precision orbit determination utilizing simulated downlink data from low earth orbit(LEO)satellites.A comprehensive investigation is conducted on the orbit determination performance,considering a simulated Walker 90/10/1 LEO satellite constellation with an orbit altitude of 1000 km and an inclination angle of 48°,along with 150 ground stations equipped with corresponding orbit clocks and observation data.The observational data from global station networks,featuring station numbers ranging from 60 to 150,are utilized for precise orbit determination of LEO satellites,followed by a detailed analysis of orbit accuracy and station position dilution of precision(SPDOP)values.Results indicate a significant enhancement in LEO satellite orbit accuracy from 117.5 mm to 39.8 mm upon increasing the number of stations from 60 to 150.Furthermore,sparse station distribution leads to a rapid degradation in LEO satellite orbit accuracy.The study underscores the effectiveness of augmenting the number of ground stations in improving both visible station SPDOP and LEO satellite orbit accuracy over terrestrial regions.However,due to the constrained tracking range of stations,enhancing the orbit accuracy of LEO satellites in marine regions remains challenging.