卫星轨道参数对北斗GEO卫星多径效应影响的分析

摘要

在我国的北斗导航系统以及其他国家的星基导航系统中，地球同步轨道（ GEO）卫星不仅用于播发增强信号，还作为测距源使用。同时GEO卫星多径干扰是制约卫星导航系统整体性能的一个不可忽略的因素。通过建立多径衰落数学模型，详细分析了GEO卫星多径衰落的机理，深入研究了卫星轨道参数对多径衰落的影响。通过对不同监测站实测数据的分析，北斗系统中倾斜地球同步轨道（ IGSO）卫星和中地球轨道（ MEO）卫星的多径衰落特性与其相应卫星的高度角存在相关性，但并未发现GEO卫星的多径衰落也拥有类似的特征。通过分析开普勒多径衰落因子KMPF的第一和第二零陷点的衰落特性，可在一定程度上反映出GEO卫星多径误差的变化。最后通过仿真实验证明了开普勒多径衰落因子对分析GEO卫星多径误差提供了重要的研究手段。%In Beidou navigation satellite system and satellite⁃based augmentation system ( SBAS) from foreign coun⁃tries, the Geostationary Earth Orbit ( GEO) satellites not only send augmentation signals, but be used as a ranging source. Moreover the multipath noises from GEO constraint BeiDou receiver to provide a high⁃precision positioning service, which is not negligible. By designing multipath fading mathematical model, the mechanism of multipath fa⁃ding from GEO satellites is fully analyzed, and the effects of satellite orbit parameters on multipath fading are deep⁃ly studied. Based on the analysis of the measurements from different monitoring stations, the multipath error curves of MEO and IGSO satellites are correlated with the elevation angle, but this correlation is not in GEO satellites mul⁃tipath errors. This paper proposes a method, by analyzing the fading trend of the first nulling point and second null⁃ing point of Kepler multipath fading ( KMPF) factor, which can reflect variation trend of the multipath error of GEO. Finally, the simulation results verifies that the KMPF factor provides an important method to analyze the GEO multipath errors.