Galileo完备性系统中WUL算法研究

Study of WUL algorithm of Galileo system

本文详细分析了Galileo系统中WUL的计算步骤,首先把WUL点从空间固定到球体的一个大圆,确定出WUL在球体上的坐标,进而利用椭球和球之间的关系,把WUL点转化到椭球面上,最后通过实例进行分析可知,在相同误差不同的卫星位置之下,该WUL算法计算出的WUL距离误差都在厘米级且变化范围较小,最大差异为1.6cm;在同一卫星同一轨道位置不同的轨道误差之下,计算出的WUL的距离误差变化较小,最大值和最小值之差为0.36cm,进而可知该WUL算法得出的距离误差具有数值稳定性且精度较高,能够满足WUL的计算要求。

The paper analyzed the process of computing the Worst User Location （WUL） of Galileo system in detail. Firstly, it spatially determined WUL to a big circle of sphere, calculated the coordinate of WUL on the sphere, then transformed it from sphere to ellipsoid ; lastly, used this method to calculate WUL. The result was that the distance errors based on the difference location of satellite and same orbit errors were in centimeter level with 1.6era as greatest difference, and the distance errors based on the same location of satellite and different orbit errors changed little, the difference of the largest and least value was 0. 36era; they proved that this method could meet the demanding preeision of WUL and the distance errors calculated by using this method was stable and high precision.