北斗新一代试验卫星星钟及轨道精度初步分析  

Orbit determination and time synchronization for new-generation Beidou satellites:Preliminary results

作　　者：陈金平 胡小工[2,3] 唐成盼[2,4] 周善石[2,3] 郭睿 潘军洋 李冉[2,4] 朱陵凤 

机构地区：[1]北京卫星导航中心,北京100094 [2]中国科学院上海天文台,上海200030 [3]上海市定位与导航重点实验室,上海200030 [4]中国科学院大学,北京100049

出　　处：《中国科学：物理学、力学、天文学》2016年第11期79-89,共11页Scientia Sinica Physica,Mechanica & Astronomica

基　　金：国家自然科学基金(编号:41374038;41574029);上海市定位与导航重点实验室和中国科学院青年创新促进会(编号:2016242)资助项目

摘　　要：北斗卫星导航系统新一代试验卫星星座由2颗高轨倾斜地球同步轨道卫星和3颗中轨地球轨道卫星组成,2016年2月全部发射入轨,其任务是验证北斗系统从目前区域导航定位授时服务走向全球服务的新技术体制设计及指标性能.导航卫星星载原子钟是最重要载荷之一,负责星上时间频率基准信号维持和产生,本文利用星地双向时频传递设备观测的星地钟差数据,评估了试验星配置的新型高精度铷钟和被动型氢钟的实际性能,定量比较了相对于北斗区域系统卫星钟的性能提升.结果表明新一代试验星与北斗区域系统卫星钟差预报精度相比较有较大提高,地球倾斜静止卫星(Inclined Geosynchronous Orbit,IGSO)短期预报误差从0.65ns减小到0.30ns,中轨道卫星(Medium Orbit,MEO)短期预报误差从0.78ns减小到0.32ns,IGSO/MEO卫星中期预报误差均从2.50ns减小到约1.50ns.星间链路(Inter-Satellite Link,ISL)是北斗全球系统最重要的技术体制设计之一,本文评估了试验卫星实现的星间伪距测量对提升空间信号精度,即轨道和钟差的贡献,得到在地面监测网无法连续覆盖到的境外弧段,高精度星间链路测量对轨道确定和钟差测定精度的提升尤为明显.加入星间伪距测量,MEO卫星重新入境时钟差预报误差由3ns减小至1ns以内.采用星地星间联合定轨方法估计的卫星轨道径向重叠弧段互差优于0.1m,三维位置重叠互差优于0.5m,预报24h径向重叠弧段互差优于0.2m,三维位置重叠互差优于1m,均较区域监测网L波段定轨结果有较大提升.为解决多星定轨处理时卫星钟差与轨道高度耦合问题,本文提出了卫星钟差半约束模式定轨处理方法.用户等效距离误差分析结果表明采用卫星钟差半约束的定轨模式,卫星轨道预报4h用户等效距离误差由1.04m减小至0.82m.Five new-generation Beidou Satellite Navigation System （BDS） satellites, including two satellites in the Inclined Geostationary Orbit （IGSO） and three satellites in the Medium Orbit （MEO）, have completed deployment on 1st February 2016. The mission of the five new-generation satellites is to validate the new system designs and the new technologies that will successfully expand BDS＇s Positioning, Navigation and Timing （PNT） services from regional to global. Responsible to keep time and frequency standards that are used to generate navigation signals, atomic clocks are important payloads onboard BDS satellites. Using data from BDS＇ two-way satellite time and frequency transfer system, this paper evaluates performance of those new generation atomic clocks （Hydrogen Maser and Rubidium）. Compared to the regional operational satellites onboard atomic clocks, the prediction accuracy of the new-generation onboard atomic clocks is improved. The short-term prediction error of IGSO satellites drops from 0.65 to 0.30 ns, the short-term prediction error of MEO satellites drops from 0.78 to 0.32 ns, and the media-term prediction error of IGSO and MEO satellites drops from 2.50 to 1.50 ns. Inter-Satellite Links （ISL） with measurement and data communication capabilities is one of the most important ingredient for global BDS system design. With ISL data collected for the five new-generation satellites, this paper compares differences in space signal accuracy, or orbits and clocks in broadcast navigation messages, with or without ISL contribution. Our finding confirms ISL contributes a great deal to the space signal accuracy, in particular when the satellites are not tracked by a regional network. With ISL measurements, the prediction error of MEO broadcast satellite clock parameters drops from 3 ns to within 1 ns when the MEO satellites go into the visual field once more. When ISL measurements join orbit determination as additional observation to L Band code and phase measurements, the orbit determinat

关 键 词：北斗卫星导航系统 星载原子钟 星间链路 卫星钟差 卫星定轨 空间信号精度 星地双向时频传递 

分 类 号：TN967.1[电子电信—信号与信息处理]