北斗导航系统自2018年12月27日提供全球服务以来,其服务性能受到了极大关注.以上海天文台iGMAS (International GNSS Monitoring&Assessment System)分析中心发布的精密轨道、钟差产品作为基准,评估了2019年年积日3-12d的北斗二号...北斗导航系统自2018年12月27日提供全球服务以来,其服务性能受到了极大关注.以上海天文台iGMAS (International GNSS Monitoring&Assessment System)分析中心发布的精密轨道、钟差产品作为基准,评估了2019年年积日3-12d的北斗二号、北斗三号以及GPS广播星历的轨道、钟差和空间信号用户测距误差(Signal in Space User Ranging Error, SISURE,简称为URE),并且对北斗卫星导航系统结果进行了详细的分析.结果表明:在评估时间段内,北斗三号广播星历轨道精度、URE均明显优于北斗二号,且部分结果优于GPS.北斗三号广播星历轨道径向精度最高,优于0.2m.北斗三号全部卫星URE均值优于0.4m, URE RMS (root mean square)优于0.5m.北斗二号每颗卫星URE均值、95%URE (置信度为95%的URE)、URE RMS小于2m,北斗三号每颗卫星URE均值、95%URE、URE RMS小于1m,均达到了系统公开承诺的服务性能标准.展开更多
To enhance the integrity, an analytic method （AM） which has less execution time is proposed to calculate the user differential range error （UDRE） used by the user to detect the potential risk. An ephemeris and clo...To enhance the integrity, an analytic method （AM） which has less execution time is proposed to calculate the user differential range error （UDRE） used by the user to detect the potential risk. An ephemeris and clock correction calculation method is introduced first. It shows that the most important thing of computing UDRE is to find the worst user location （WUL） in the service volume. Then, a UDRE algorithm using AM is described to solve this problem. By using the covariance matrix of the error vector, the searching of WUL is converted to an analytic geometry problem. The location of WUL can be obtained directly by mathematical derivation. Experiments are conducted to compare the performance between the proposed AM algorithm and the exhaustive grid search （EGS） method used in the master station. The results show that the correctness of the AM algorithm can be proved by the EGS method and the AM algorithm can reduce the calculation time by more than 90%. The computational complexity of this proposed algorithm is better than that of EGS. Thereby this algorithm is more suitable for computing UDRE at the master station.展开更多
星基增强导航系统（SBAS,Satellite Based Augmentation System）通过向用户提供用户差分距离误差（UDRE,User Differential Range Error）,来保证广播星历和星钟改正数的精度并增强用户的完好性性能.给出了一种用于主控站的UDRE计算方...星基增强导航系统（SBAS,Satellite Based Augmentation System）通过向用户提供用户差分距离误差（UDRE,User Differential Range Error）,来保证广播星历和星钟改正数的精度并增强用户的完好性性能.给出了一种用于主控站的UDRE计算方法,提出了卫星监视几何精度因子（SSDOP,Satellite Surveillance Dilution of Precision）的概念.基于UDRE和SS-DOP的表达式,通过数学推导发现UDRE受到SSDOP和限制因子的影响,而限制因子可以用其统计平均值0.7438来替代,建立了由SSDOP估计UDRE的表达式.仿真结果表明：利用SS-DOP估计出的UDRE值,其误差不超过0.8 m,能够反映出当前卫星UDRE的特性,可以作为用户在无法接收完好性信息时快速推算UDRE的一种可行手段.展开更多
文摘北斗导航系统自2018年12月27日提供全球服务以来,其服务性能受到了极大关注.以上海天文台iGMAS (International GNSS Monitoring&Assessment System)分析中心发布的精密轨道、钟差产品作为基准,评估了2019年年积日3-12d的北斗二号、北斗三号以及GPS广播星历的轨道、钟差和空间信号用户测距误差(Signal in Space User Ranging Error, SISURE,简称为URE),并且对北斗卫星导航系统结果进行了详细的分析.结果表明:在评估时间段内,北斗三号广播星历轨道精度、URE均明显优于北斗二号,且部分结果优于GPS.北斗三号广播星历轨道径向精度最高,优于0.2m.北斗三号全部卫星URE均值优于0.4m, URE RMS (root mean square)优于0.5m.北斗二号每颗卫星URE均值、95%URE (置信度为95%的URE)、URE RMS小于2m,北斗三号每颗卫星URE均值、95%URE、URE RMS小于1m,均达到了系统公开承诺的服务性能标准.
文摘To enhance the integrity, an analytic method （AM） which has less execution time is proposed to calculate the user differential range error （UDRE） used by the user to detect the potential risk. An ephemeris and clock correction calculation method is introduced first. It shows that the most important thing of computing UDRE is to find the worst user location （WUL） in the service volume. Then, a UDRE algorithm using AM is described to solve this problem. By using the covariance matrix of the error vector, the searching of WUL is converted to an analytic geometry problem. The location of WUL can be obtained directly by mathematical derivation. Experiments are conducted to compare the performance between the proposed AM algorithm and the exhaustive grid search （EGS） method used in the master station. The results show that the correctness of the AM algorithm can be proved by the EGS method and the AM algorithm can reduce the calculation time by more than 90%. The computational complexity of this proposed algorithm is better than that of EGS. Thereby this algorithm is more suitable for computing UDRE at the master station.
文摘星基增强导航系统（SBAS,Satellite Based Augmentation System）通过向用户提供用户差分距离误差（UDRE,User Differential Range Error）,来保证广播星历和星钟改正数的精度并增强用户的完好性性能.给出了一种用于主控站的UDRE计算方法,提出了卫星监视几何精度因子（SSDOP,Satellite Surveillance Dilution of Precision）的概念.基于UDRE和SS-DOP的表达式,通过数学推导发现UDRE受到SSDOP和限制因子的影响,而限制因子可以用其统计平均值0.7438来替代,建立了由SSDOP估计UDRE的表达式.仿真结果表明：利用SS-DOP估计出的UDRE值,其误差不超过0.8 m,能够反映出当前卫星UDRE的特性,可以作为用户在无法接收完好性信息时快速推算UDRE的一种可行手段.
