多站扩频测距下的卫星定位GDOP分析

GDOP Analysis of Satellite Positioning by Multi-Station DSSS Ranging

根据GPS多星测距定位原理,提出在地面使用多个测站对空间飞行器进行多站测距定位,在分析其定位原理的基础上,进行定位解算的数学推导,给出几何衰减因子(Geometric Dilution Of Precision, GDOP)的理论公式,最后根据GDOP进行理论仿真,同时给出结论。结论认为,在三站测距定位时,GDOP最佳值为1.732;对于近地空间飞行器(高度在1000km以下),测站间地心角应在30°~60°较好,且测站布局应接近于正三角形;若能增加测站,同时改善测站的几何布局(接近于正多边形时),可以获得更好的定位效果。

With respect to LEO(Low Earth Orbit)satellite positioning in TTC(Tracking,Telemetry and Command),a multi-station tracking method has presented with multi-satellite positioning theory from GPS(Global Positioning System)to increase orbital determination precision by DSSS(Direct Spread Spectrum Signal)ranging.After derivation of mathematical positioning solution,GDOP(Geometric Dilution of Precision)formula has obtained to analyze error and precision influence computationally.With simulation,the result has shown that when three TTC stations are placed in regular triangle,the minimum GDOP is about 1.732,and when satellite height is between 200km and 1000km,the Earth core angle of two stations is better to be between 30°and 60°,and when stations are more than 3 and approximately placed in regular polygon,the GDOP value is more better.