多全球导航卫星系统联合的探月飞行器轨道定位分析

Analysis of multi-GNSS united lunar explorer orbit positioning

针对探月飞行器月球公转轨道上的卫星导航定位问题,以高轨道飞行器卫星导航定位的研究为基础,采用多全球导航卫星系统联合定位的方法进行仿真。分析了载波功率与噪声功率密度比为15d BHz的弱信号捕获门限下,各系统联合定位时波束主瓣和旁瓣的可用性,同时对各系统联合情况下的精度因子值进行分析。仿真结果表明:当接收到的卫星天线辐射的主瓣和旁瓣信号均高于载噪比门限时,全球导航卫星系统的三系统或四系统的联合能满足实时定位条件;而旁瓣损耗不加以补偿时,接收信号载噪比低于门限并导致任意联合方式均无法完成定位。各系统联合的精度因子分析表明:单系统或双系统联合的几何精度因子变化剧烈,四系统联合相比三系统联合的几何精度因子下降16.93%;三系统联合定位方案中,美国全球定位系统、中国的北斗卫星导航定位系统与欧洲的伽利略卫星导航定位系统联合方案的几何精度因子值变化最平稳,为最佳选择。理论分析和仿真结果为探月飞行器定位技术研究和星载多系统接收机设计提供参考。

Muhi-GNSS （Global Navigation Satellite System） united positioning was simulated based on researches of high earth orbital positioning. On the weakest signal acquisition C/N0 threshold, 15dBHz, feasibility of satellite beam main lobe and side lobe receiving was analyzed, and the dilution of precision values with different GNSS system united cases were also analyzed. Simulation results show that when the receiving signal＇ s C/N0 of both main lobe and side lobe is larger than the threshold, 3 systems united or more can satisfy positioning. When the side lobe loss isn ＇ t compensated, C/N0 of receiving signal is weaker than threshold so that any case of multi-system united can ＇ t realize positioning. Analysis of dilution of precision values shows that geometrical dilution of precision of single system and double systems united changes violently. Geometrical dilution of precision of 4 systems united decreases 16.93% than that of 3 systems united. On the condition of 3 systems united, the case of American GPS （Global Position System） united with Chinese BDS （BeiDou navigation satellite System） and European Galileo system（ Galileo satellite navigation system） is best since its geometrical dilution of precision is smoother than others. Theory analysis and simulation results provide beneficial suggestions for researching of lunar explorer positioning and space borne GNSS multi-system receiver.