To provide competitive global positioning and timing services under the condition that monitoring stations are confined to Chinese territory,inter-satellite link(ISL)technology is used by the third-generation BeiDou N...To provide competitive global positioning and timing services under the condition that monitoring stations are confined to Chinese territory,inter-satellite link(ISL)technology is used by the third-generation BeiDou Navigation Satellite System(BDS-3).The ISL,together with the dual one-way links between satellites and anchor stations,may enable autonomous navigation for BDS-3.In this paper,we propose a general observation model for orbit determination(OD)and time synchronization(TS)directly using non-simultaneous observations,such as raw ISL pseudoranges.With the proposed model,satellite orbits,clocks,and hardware delay biases of ISL equipment can be determined simultaneously by jointly processing inter-satellite one-way pseudorange data and observation data from ground monitoring stations.Moreover,autonomous OD and TS are also achievable with one-way pseudorange data from anchor stations and satellites.Data from eight BDS-3 satellites,two anchor stations,and seven monitoring stations located in China were collected to validate the proposed method.It is shown that by jointly processing data from the ISL and seven monitoring stations,the RMS of overlap orbit differences in radial direction is 0.019 m,the overlap clock difference(95%)is 0.185 ns,and the stability of the estimated hardware delay biases for each satellite is greater than 0.5 ns.Compared with the results obtained with the seven stations,the improvements of orbits in radial direction and clocks are 95.7%and 90.5%,respectively.When the hardware delay biases are fixed to predetermined values,the accuracies of orbits and clocks are further improved.By jointly processing pseudoranges from the satellites and the two anchor stations,the RMS of overlap orbit differences is 0.017 m in the radial direction,and the overlap clock difference(95%)is 0.037 ns.It has also been demonstrated that under the condition of one-way ranging links,the accuracies of orbits and clocks obtained by the above two modes are still significantly better than those obtained by using the data from the monitoring stations alone.展开更多
基金the National Natural Science Foundation of China(Grant Nos.41704035 and 42774012)Office of China Navigation Satellite System(Project No.GFZX03010403).
文摘To provide competitive global positioning and timing services under the condition that monitoring stations are confined to Chinese territory,inter-satellite link(ISL)technology is used by the third-generation BeiDou Navigation Satellite System(BDS-3).The ISL,together with the dual one-way links between satellites and anchor stations,may enable autonomous navigation for BDS-3.In this paper,we propose a general observation model for orbit determination(OD)and time synchronization(TS)directly using non-simultaneous observations,such as raw ISL pseudoranges.With the proposed model,satellite orbits,clocks,and hardware delay biases of ISL equipment can be determined simultaneously by jointly processing inter-satellite one-way pseudorange data and observation data from ground monitoring stations.Moreover,autonomous OD and TS are also achievable with one-way pseudorange data from anchor stations and satellites.Data from eight BDS-3 satellites,two anchor stations,and seven monitoring stations located in China were collected to validate the proposed method.It is shown that by jointly processing data from the ISL and seven monitoring stations,the RMS of overlap orbit differences in radial direction is 0.019 m,the overlap clock difference(95%)is 0.185 ns,and the stability of the estimated hardware delay biases for each satellite is greater than 0.5 ns.Compared with the results obtained with the seven stations,the improvements of orbits in radial direction and clocks are 95.7%and 90.5%,respectively.When the hardware delay biases are fixed to predetermined values,the accuracies of orbits and clocks are further improved.By jointly processing pseudoranges from the satellites and the two anchor stations,the RMS of overlap orbit differences is 0.017 m in the radial direction,and the overlap clock difference(95%)is 0.037 ns.It has also been demonstrated that under the condition of one-way ranging links,the accuracies of orbits and clocks obtained by the above two modes are still significantly better than those obtained by using the data from the monitoring stations alone.
文摘全球卫星导航系统(global navigation satellite system,GNSS)星载原子钟性能的优劣直接影响GNSS观测信号质量、测距精度、钟差预报与卫星自主导航能力,从而间接影响整个导航系统的服务性能。结合北斗三号系统独特的星间链路(inter-satellite link,ISL)和星地时间双向比对(two-way time transfer,TWTT)体制以及常用的精密轨道与钟差确定(orbit determination and time synchronization,ODTS)体制所估计的精密钟差数据,分析评估了北斗三号在轨原子钟服务性能。结果表明,3种钟差确定体制评估的频率准确度和漂移率结果基本一致,所有卫星频率准确度在(-4~2)×10^(-11)范围以内,氢钟频率准确度优于铷钟,ISL钟差评估的频率漂移率精度略优于ODTS。在评估原子钟稳定度方面,3种钟差确定体制各有优势,短期稳定度方面,ODTS钟差评估优于ISL钟差,基于ODTS评估的3000 s稳定度可达3×10^(-14),且氢钟的短期稳定性优于铷钟;中长期稳定度方面,当平滑时间大于1×10^(4)s时,采用ISL体制的钟差评价中长期稳定度更接近于北斗三号星载原子钟的实际情况;对于7 d以上的长期稳定度评估,基于TWTT的广播钟差评估结果接近于ISL,可用于快速评估。
