陆态网络数据的北斗观测值特性分析

Characteristics analysis of BDS observations based on CMONOC data

为了进一步分析北斗卫星观测值的相关特性,文章对比北斗卫星与GPS卫星、以及不同类型北斗卫星之间观测值特性的差异,提出了用站间差分考察伪距多路径组合和GFIF组合观测值的方法。陆态网络数据实验结果显示,北斗卫星B1频率观测值的信噪比最低;高度角较低时,北斗卫星伪距多路径组合绝对值和离散度均较大,约为1.5m,且IGSO和MEO卫星的伪距多路径组合值随高度角增大而明显降低;北斗GEO和IGSO卫星的相位GFIF组合有日周期性,变化范围约为±2cm,伪距GFIF组合的变化范围可达±2m;站间差分可明显减弱伪距多路径组合的变化趋势和相位GFIF组合的周期性,表明这两个组合中可能包含与卫星相关的误差,为北斗观测数据误差处理提供参考。

In order to further analyze the correlative characteristic of BDS observations,the paper compared the different behaviors not only between the BDS and GPS satellites,but also among different types of BDS satellites,and proposed to investigate pseudorange multipath combination and GFIF combination with the method of between-station-differencing.Experiments with observations from the stations of Crustal Movement Observation Network of China（CMONOC）demonstrated that the SNR of B1 observables are the lowest among three BDS frequencies;when the elevation angles are relatively small,both the absolute values and dispersions of multipath combinations become large,with the absolute values reaching about 1.5m;meanwhile,the multipath combinations of IGSO and MEO satellites decrease significantly with the increase of elevation;daily periodicity is found in the GFIF combinations of both GEO and IGSO satellites,with an variation of±2cm for carrier phase and±2mfor pseudorange.Both the trend of multipath combination and the periodicity of carrier phase GFIF combination could be significantly mitigated through between-station-differencing,showing that some satellite dependent errors are likely contained in the two combinations.The above results would provide a reference for properly handling the errors in BDS observations.