故障星分布对星座PDOP可用性影响的建模及评价

Modeling and Evaluation of Effects of Fault Satellites Distribution on PDOP Availability of Navigation Constellation

导航星座定位精度衰减因子(PDOP)可用性是卫星导航系统顶层设计的重要指标。研究了不同故障星分布状况对全球导航星座PDOP可用性的影响。首先,从概率角度并采用组合方法建立了全球导航星座PDOP可用性指标的统计评价模型。进而对给定数量的故障星分布在单个或多个轨道面内的不同状况下,典型的Walker-δ构型导航星座的PDOP可用性如何变化进行了仿真计算和比较分析。仿真结果表明,故障星分布状况和轨道平面数对星座PDOP可用性有较显著影响,适当地减少轨道平面数对于改善星座的PDOP可用性是有利的。提出的评价模型物理意义明确,避免了主观性和局限性,且可以保证较高的指标评价效率。

Positioning dilution of precision （PDOP） availability of navigation constellation is one of the important specifications in the phase of general system design. Effects of different distributions of fault satellites on PDOP availability of global navigation constellation are studied. Firstly, a statistical evaluation model of PDOP availability is suggested using probability and combination method. Using this model, simulation and analysis for variation of PDOP availability of navigation constellations with typical Walker-δ configurations are performed, considering that a given number of fault satellites distribute in one or more orbital planes. The simulation results indicate that the distribution of fault satellites and the number of orbital planes have notable effects on PDOP availability of constellation, and that it is advantageous to reduce the number of orbital planes properly to improve PDOP availability of global navigation constellation. The proposed model has explicit physical meaning and can avoid the subjectivity and ensure the effectiveness of specification evaluation.