Satellite Based Augmentation Systems(SBASs)improve the positioning accuracy and integrity by broadcasting to the civil aviation community the corrections and integrity parameters.A snapshot algorithm based on the mini...Satellite Based Augmentation Systems(SBASs)improve the positioning accuracy and integrity by broadcasting to the civil aviation community the corrections and integrity parameters.A snapshot algorithm based on the minimum variance estimation is investigated in this study to calculate the satellite clock and orbit corrections.A chi-square test is performed on the remaining errors in the corrected ephemeris to guarantee the integrity.User Differential Range Error(UDRE)and scaling matrix contained in Message Type 28 are derived using the covariance information based on the assumption that one of the reference stations failed.A software package is developed and applied in the real data collected at 26 stations.International GNSS(Global Navigation Satellite System)Service(IGS)precise clock and orbit products are taken as the references to assess the accuracy of corrections.For both Global Positioning System(GPS)and BeiDou Navigation Satellite System(BDS),the range accuracy of 0.10 m can be achieved with the employment of the derived corrections.No obvious performance difference between GPS and BDS is found.UDREs for all visible satellites are generated with the maximum index of 12 and minimum index of 3.The geometric range differences calculated with IGS precise products and broadcast ephemeris are employed to assess the integrity of UDRE.It is found that the UDRE is able to bound the residuals with 99.9%confidence which meet the requirement of aviation users.With ionospheric delay corrected by Global Ionosphere Map(GIM),the positioning accuracy of 0.98 m with GPS corrections and 0.80 m with multi-constellation augmentation can be achieved which indicates a significant improvement of GPS standalone results.展开更多
星基增强导航系统（SBAS）通过向用户提供用户差分距离误差（User differential range error,UDRE），来保证广播星历和星钟改正数的精度。本文设计了UDRE的一种改进算法，建立卫星导航系统星钟和星历误差的状态方程和量测方程，进行卡...星基增强导航系统（SBAS）通过向用户提供用户差分距离误差（User differential range error,UDRE），来保证广播星历和星钟改正数的精度。本文设计了UDRE的一种改进算法，建立卫星导航系统星钟和星历误差的状态方程和量测方程，进行卡尔曼滤波计算星历与星钟误差改正数与改正精度，通过滤波误差估计精度矩阵计算UDRE，针对基准站对卫星UDRE影响因素，仿真分析基准站高度截止角和数目分布对三种卫星倒DOP及UDRE的影响，仿真结果表明：基准站的高度截止角选为15°，基准站数目选择20个以上较为合适。展开更多
星基增强系统(satellite based augmentation system,SBAS)通过地球同步轨道卫星实时播发导航卫星星历改正数和完好性参数,以提升用户定位精度和完好性。采用最小方差法解算GPS星历改正数,利用卡方统计进行改正数完好性检核,并依据星历...星基增强系统(satellite based augmentation system,SBAS)通过地球同步轨道卫星实时播发导航卫星星历改正数和完好性参数,以提升用户定位精度和完好性。采用最小方差法解算GPS星历改正数,利用卡方统计进行改正数完好性检核,并依据星历改正数方差-协方差信息计算SBAS用户差分距离误差(user differential range error,UDRE)和信息类型28(message type 28, MT28)等完好性参数。利用中国区域27个监测站的实测数据,首先以国际GNSS服务组织的精密轨道和钟差产品为参考解算星历改正数,结果表明,钟差改正精度优于0.1 m,轨道改正精度优于0.4 m;然后解算广播星历改正数,并生成UDRE和MT28参数,广播星历残余误差卡方检验值均小于告警门限,保证了改正数的完好性;最后利用生成的改正数进行SBAS定位解算,得到定位结果的水平精度优于0.7 m,垂直精度优于1.0 m,对比GPS单点定位,所提算法的水平和垂直方向精度分别提升了30%和40%。展开更多
基金the Equipment Pre-research Foundation of China(No.61405180103)the National Natural Science Foundation of China(No.41974041).
文摘Satellite Based Augmentation Systems(SBASs)improve the positioning accuracy and integrity by broadcasting to the civil aviation community the corrections and integrity parameters.A snapshot algorithm based on the minimum variance estimation is investigated in this study to calculate the satellite clock and orbit corrections.A chi-square test is performed on the remaining errors in the corrected ephemeris to guarantee the integrity.User Differential Range Error(UDRE)and scaling matrix contained in Message Type 28 are derived using the covariance information based on the assumption that one of the reference stations failed.A software package is developed and applied in the real data collected at 26 stations.International GNSS(Global Navigation Satellite System)Service(IGS)precise clock and orbit products are taken as the references to assess the accuracy of corrections.For both Global Positioning System(GPS)and BeiDou Navigation Satellite System(BDS),the range accuracy of 0.10 m can be achieved with the employment of the derived corrections.No obvious performance difference between GPS and BDS is found.UDREs for all visible satellites are generated with the maximum index of 12 and minimum index of 3.The geometric range differences calculated with IGS precise products and broadcast ephemeris are employed to assess the integrity of UDRE.It is found that the UDRE is able to bound the residuals with 99.9%confidence which meet the requirement of aviation users.With ionospheric delay corrected by Global Ionosphere Map(GIM),the positioning accuracy of 0.98 m with GPS corrections and 0.80 m with multi-constellation augmentation can be achieved which indicates a significant improvement of GPS standalone results.
文摘星基增强导航系统（SBAS）通过向用户提供用户差分距离误差（User differential range error,UDRE），来保证广播星历和星钟改正数的精度。本文设计了UDRE的一种改进算法，建立卫星导航系统星钟和星历误差的状态方程和量测方程，进行卡尔曼滤波计算星历与星钟误差改正数与改正精度，通过滤波误差估计精度矩阵计算UDRE，针对基准站对卫星UDRE影响因素，仿真分析基准站高度截止角和数目分布对三种卫星倒DOP及UDRE的影响，仿真结果表明：基准站的高度截止角选为15°，基准站数目选择20个以上较为合适。
文摘星基增强系统(satellite based augmentation system,SBAS)通过地球同步轨道卫星实时播发导航卫星星历改正数和完好性参数,以提升用户定位精度和完好性。采用最小方差法解算GPS星历改正数,利用卡方统计进行改正数完好性检核,并依据星历改正数方差-协方差信息计算SBAS用户差分距离误差(user differential range error,UDRE)和信息类型28(message type 28, MT28)等完好性参数。利用中国区域27个监测站的实测数据,首先以国际GNSS服务组织的精密轨道和钟差产品为参考解算星历改正数,结果表明,钟差改正精度优于0.1 m,轨道改正精度优于0.4 m;然后解算广播星历改正数,并生成UDRE和MT28参数,广播星历残余误差卡方检验值均小于告警门限,保证了改正数的完好性;最后利用生成的改正数进行SBAS定位解算,得到定位结果的水平精度优于0.7 m,垂直精度优于1.0 m,对比GPS单点定位,所提算法的水平和垂直方向精度分别提升了30%和40%。
