IGS站的几何结构与数量对GPS导航星座精密轨道确定的影响分析

INFLUENCE OF GEOMETRY AND NUMBER OF IGS STATION ON PRECISE ORBIT DETERMINATION OF GPS NAVIGATION CONSTELLATION

基于2008年年积日87—95天的不同几何结构和数量的IGS站的观测数据,分别解算GPS导航星座的一天解、三天解和七天解。通过与IGS发布的精密轨道做比较,结果表明,利用结构优化后的40个IGS站的观测数据解算GPS导航星座的一天解、三天解和七天解,其精度分别能达到4.9、3.6和3.4 cm,但IGS站达到一定数量之后,GPS导航星座轨道精度不会随着观测站数量的增加而显著提高,反而使解算的时间增长;固定IGS站的数量之后,IGS站的几何结构是影响轨道精度的关键因素。

One-day, three-day and seven-day orbit solutions of GPS navigation constellation based on the ob- servations of IGS stations in different numbers and geometries from 87-day to 95-day in 2008 were determined. The final solutions were compared with IGS precise ephemeris. The result shows that the accuracy of one-day, three-day and seven-day orbit solutions could reach up to 4.9 cm, 3.6 cm and 3.4 cm when optimal geometry of the 40 IGS stations are selected. With the increase of [GS stations, the orbit accuracy could not be remarkably improved when the IGS stations have reached a certain limit, but computing time become longer. Thus it is evident that the geome- try is the key factor which affects the accuracy of the final solution when the number of IGS stations is fixed.