GNSS几何性能仿真分析

Simulation Analysis of GNSS Geometric Performance

卫星的可见性和几何性能制约着导航定位精度以及定位可用性等。在分析卫星可见性和PDOP理论基础上,为提高导航定位精度,以北京地区为例,使用基于星座轨道模型方向余弦的计算方法,研究分析了三系统的卫星可见性随截止高度角的变化关系,对GDOP值的变化进行仿真试验。同时对在低纬度地区、中纬度地区以及高纬度地区的GDOP值变化做了对比分析。试验结果表明,Galileo系统的卫星满足定位要求,GPS和GLONASS(不包括增强系统)缺少稳定性;在低纬度区域,Galileo几何性能优于GPS,GPS优于GLONASS;在高纬度地区GLONASS具有最优的几何性能,GPS次之,而Galileo则极不稳定。

Satellite visibility and geometric performance restrict the precision of navigation and positioning as well as the availability of such position. In this paper, take the Beijing area as an example, using the constellation model and its cosine calculation algorithm, the changing relationship between the satellite visibility and its elevation angle in the GPS, Galileo and GLONASS was researched and analyzed based on the satellite visibility and GDOP theory. The GDOP＇s value change in the world region was simulated, at a 24 - hour cycle, and a comparative analysis of the GDOP＇s value change at low latitudes, mid - latitudes, and high latitudes was made. Finally the conclusion was drawn that with the elevation angle increasing（ 〈 30deg）, Galileo system always meets the positioning requirements, while GPS and GLONASS can not（ not include GPS Augmentation System）. On low latitude regions, Galileo geometric properties are superior to GPS, and GPS geometric properties are superior to GLONASS. GLONASS has good GDOP values and geometric performance at high latitudes.