An investigation has been made on the models and characteristics of triple-frequency carrier-phase linear combinations for the Bei Dou Navigation Satellite System(BDS). Based on the three frequencies of the BDS, three...An investigation has been made on the models and characteristics of triple-frequency carrier-phase linear combinations for the Bei Dou Navigation Satellite System(BDS). Based on the three frequencies of the BDS, three categories of combinations are developed: ionosphere-free combinations(i.e., those that eliminate the ionospheric effect), minimum-noise combinations(those that mitigate the effects of thermal noise and multiple paths), and troposphere-free combinations(those that mitigate tropospheric effects). Both the ionosphere-free and troposphere-free combinations can be expressed as planes, whereas the minimum-noise combinations can be expressed as a line. The relationships between these three categories of linear combinations are investigated from the perspective of geometry. The angle between the troposphere-free plane and ionosphere-free plane is small, while the angles between the troposphere-free plane and the minimum-noise line, and between the ionosphere-free plane and the minimum-noise line, are large. Specifically, the troposphere-free plane is orthogonal to the minimum-noise line. By introducing the concepts of lane number and integer ionosphere number, the characteristics of the long-wavelength integer combinations and ionosphere-free integer combinations are investigated. The analysis indicates that the longest wavelength that can be formed for integer combinations is 146.53 m, and the ionosphere-free integer combinations all have large noise amplification factors. The ionosphere-free integer combination with minimum noise amplification factor is(0, 62, 59). According to the lane number, integer ionosphere number, and noise amplification factor, optimal integer combinations with different characteristics are presented. For general short baselines and long baselines, three independent integer combinations are suggested.展开更多
无电离层组合模型和非差非组合模型是精密单点定位(precise point positioning,PPP)中最常用的两种函数模型。非差非组合模型中电离层误差常被描述为随机游走,随机游走过程中的功率谱密度成为决定PPP定位性能的主要因素,采用经验值功率...无电离层组合模型和非差非组合模型是精密单点定位(precise point positioning,PPP)中最常用的两种函数模型。非差非组合模型中电离层误差常被描述为随机游走,随机游走过程中的功率谱密度成为决定PPP定位性能的主要因素,采用经验值功率谱密度的方法没有考虑电离层小尺度变化。在非差非组合模型的基础上,分析电离层时间相关性信息,在电离层差分时间间隔较小时,观测噪声较大甚至淹没电离层的变化。因此,通过平滑去噪的方法削弱观测值噪声的影响,实时确定电离层功率谱密度,对非差非组合模型中的电离层延迟参数进行合理约束,从而改善定位性能。对12个测站10 d的北斗卫星导航系统(BeiDou satellite navigation system,BDS)数据进行不同电离层模型下的解算,结果表明:相对于传统无电离层组合PPP模型,所提方法在收敛时间上缩短约8.2%,水平方向精度相当,垂直方向定位精度提高约31%。相较于功率谱密度采用经验值方法,所提方法在收敛时间上缩短约9.7%,水平方向精度相当,垂直方向定位精度提高约31%。展开更多
近年来,随着多系统全球导航卫星系统(global navigation satellite system,GNSS)的迅速发展以及实时高精度应用需求的日益增长,国际GNSS服务分析中心(International GNSS Service,IGS)提供的状态空间表述(state space representation,S...近年来,随着多系统全球导航卫星系统(global navigation satellite system,GNSS)的迅速发展以及实时高精度应用需求的日益增长,国际GNSS服务分析中心(International GNSS Service,IGS)提供的状态空间表述(state space representation,SSR)产品越来越丰富。评估不同分析中心的GNSS实时产品及其定位性能对用户具有重要参考价值。对中国科学院(Chinese Academy of Sciences,CAS)、法国太空研究中心(Centre National d’Etudes Spatiales,CNE)、德国宇航中心(Deutsches Zentrum für Luft-und Raumfahrt,DLR)、西班牙航天与防务公司(GMV Aerospace and Defense,GMV)、德国地学研究中心(Deutsches GeoForschungsZentrum,GFZ)、武汉大学(Wuhan University,WHU)6个分析中心的GPS/北斗卫星导航系统(BeiDou satellite navigation system,BDS)SSR产品的可用性、精度和实时精密单点定位性能进行了评估。实验结果表明:CAS播发的GPS卫星可用性最高,提供了所有32颗GPS卫星的SSR改正数;CAS、GFZ、WHU 3家分析中心的BDS卫星可用性相对较高,提供了15(BDS-2)+27(BDS-3)卫星的SSR改正数。在6个分析中心中,WHU的GPS卫星的三维轨道精度和钟差精度均为最佳;不同分析中心GPS卫星的信号空间测距误差(signal-in-space ranging errors,SISRE)普遍优于5 cm,不同分析中心GPS卫星的SISRE值的大小顺序为:WHU<GMV<CNE<DLR<GFZ<CAS;BDS卫星轨道钟差精度相对较差,表现最优的WHU分析中心的BDS-2和BDS-3的中地球轨道卫星精密产品的SISRE值分别为8.83、5.91 cm。在单GPS动态PPP模式下,DLR的收敛速度最慢,GFZ收敛速度最快;加入BDS卫星以后,定位精度无显著差异,但能够有效提升收敛速度。展开更多
基金sponsored by the National Natural Science Foundation of China(Grant Nos.41074024,41204030)the National Basic Research Program of China(Grant No.2013CB733301)
文摘An investigation has been made on the models and characteristics of triple-frequency carrier-phase linear combinations for the Bei Dou Navigation Satellite System(BDS). Based on the three frequencies of the BDS, three categories of combinations are developed: ionosphere-free combinations(i.e., those that eliminate the ionospheric effect), minimum-noise combinations(those that mitigate the effects of thermal noise and multiple paths), and troposphere-free combinations(those that mitigate tropospheric effects). Both the ionosphere-free and troposphere-free combinations can be expressed as planes, whereas the minimum-noise combinations can be expressed as a line. The relationships between these three categories of linear combinations are investigated from the perspective of geometry. The angle between the troposphere-free plane and ionosphere-free plane is small, while the angles between the troposphere-free plane and the minimum-noise line, and between the ionosphere-free plane and the minimum-noise line, are large. Specifically, the troposphere-free plane is orthogonal to the minimum-noise line. By introducing the concepts of lane number and integer ionosphere number, the characteristics of the long-wavelength integer combinations and ionosphere-free integer combinations are investigated. The analysis indicates that the longest wavelength that can be formed for integer combinations is 146.53 m, and the ionosphere-free integer combinations all have large noise amplification factors. The ionosphere-free integer combination with minimum noise amplification factor is(0, 62, 59). According to the lane number, integer ionosphere number, and noise amplification factor, optimal integer combinations with different characteristics are presented. For general short baselines and long baselines, three independent integer combinations are suggested.
文摘近年来,随着多系统全球导航卫星系统(global navigation satellite system,GNSS)的迅速发展以及实时高精度应用需求的日益增长,国际GNSS服务分析中心(International GNSS Service,IGS)提供的状态空间表述(state space representation,SSR)产品越来越丰富。评估不同分析中心的GNSS实时产品及其定位性能对用户具有重要参考价值。对中国科学院(Chinese Academy of Sciences,CAS)、法国太空研究中心(Centre National d’Etudes Spatiales,CNE)、德国宇航中心(Deutsches Zentrum für Luft-und Raumfahrt,DLR)、西班牙航天与防务公司(GMV Aerospace and Defense,GMV)、德国地学研究中心(Deutsches GeoForschungsZentrum,GFZ)、武汉大学(Wuhan University,WHU)6个分析中心的GPS/北斗卫星导航系统(BeiDou satellite navigation system,BDS)SSR产品的可用性、精度和实时精密单点定位性能进行了评估。实验结果表明:CAS播发的GPS卫星可用性最高,提供了所有32颗GPS卫星的SSR改正数;CAS、GFZ、WHU 3家分析中心的BDS卫星可用性相对较高,提供了15(BDS-2)+27(BDS-3)卫星的SSR改正数。在6个分析中心中,WHU的GPS卫星的三维轨道精度和钟差精度均为最佳;不同分析中心GPS卫星的信号空间测距误差(signal-in-space ranging errors,SISRE)普遍优于5 cm,不同分析中心GPS卫星的SISRE值的大小顺序为:WHU<GMV<CNE<DLR<GFZ<CAS;BDS卫星轨道钟差精度相对较差,表现最优的WHU分析中心的BDS-2和BDS-3的中地球轨道卫星精密产品的SISRE值分别为8.83、5.91 cm。在单GPS动态PPP模式下,DLR的收敛速度最慢,GFZ收敛速度最快;加入BDS卫星以后,定位精度无显著差异,但能够有效提升收敛速度。
