Research on the Influence of Stations' Distance in High-accuracy GPS Satellite Clock Offset Estimation

In the estimation of GPS satellites' clock offset,the design matrix of clock offset parameters is often considered independent with the geometric distribution of observation stations,as it has nothing to do with the coordination of the stations.However,in the high-accuracy estimation of clock offset,the troposphere delay has to estimate together,the design matrix of troposphere parameter is dependent with the observation stations,so the influence of geometric distribution of observation stations on accuracy must be taken into acc-ount.In this paper,we analyzed the influence of different observation stations distributions(from 50 km to 1 000 km) on satellite's clock offset estimation based on the PANDA software.The result shows that,when the distance between stations is shorter than 200km,the correlation of troposphere parameter and satellite clock offset parameter is strong,the accuracy of satellite clock offset estimation will be up to 0.8 ns;when the distance between stations is up to 500 km,as the correction of troposphere parameter and satellite clock offset parameter is significantly reduced,and the two kinds of parameters can be distinguished.