北斗GEO/IGSO/MEO卫星定轨地面站构型影响分析及其优化

Analysis and Optimization of BDS GEO/IGSO/MEO Ground Monitoring Stations Configuration for Determining GNSS Orbit

GNSS卫星定轨精度主要取决于卫星动力学模型精度和GNSS几何观测信息。由于北斗GEO/IGSO卫星静地、高轨特性,以及力学模型不精确等原因,地面几何观测信息对轨道改进至关重要。本文讨论了北斗GEO/IGSO/MEO卫星定轨地面站分布影响及优化改进方法。在简化动力学定轨模型基础上,探讨多历元几何观测信息累积对轨道的改进;研究了北斗导航卫星定轨理想几何构型条件,得到影响定轨精度的几何因子,包括测站数量、覆盖范围、分布密度;利用离散概率密度方法研究地面站构型,分析了3类卫星轨道改进机理和优化方法。通过算例,讨论了增加5个中国区域基准站改善离散概率密度指标,优化全球北斗卫星定轨构型,发现GEO和IGSO卫星精度改善最为明显,MEO卫星改善最小;其中GEO卫星提高了10%,IGSO卫星提高了16%,MEO卫星提高了4%。

Orbit determination accuracy of GNSS satellites depends on the satellites dynamics models and GNSS orbit determination geometry.Because of the weak geometry,higher orbit height of GEO and IGSO and relatively low accuracy of the dynamics models,the geometry information may play an important role in improving the GNSS orbit.The method for analysis the configuration and the influence of BDS GEO/IGSO/MEO ground monitoring stations distribution are discussed.Firstly,based on the reduced-dynamic orbit determination theory,the precision improvement of GNSS orbit from multi-epoch geometry observations is revealed.Secondly,the geometric condition of an ideal configuration for BDS satellites orbit determination is studied and the influence factors(quantity,range,density)are obtained.Thirdly,the method based on the discrete probability distribution is proposed to analyse the configuration of the ground monitoring stations.Finally,the indicators of discrete probability density and configuration of BDS orbit determination are optimized by adding five Chinese regional stations.It is showed that the improvement of GEO and IGSO satellites is more significant relative to MEO satellites.The accuracy of GEO/IGSO/MEO satellites is improved by 10%,16%,4%respectively.