A New GPS/BDS precise point positioning Algorithm Based on Helmet Posteriori Method

The precise point positioning(PPP) based on GPS takes about 30 minutes to obtain centimeter-level accuracy. The accuracy of positioning is also subject to the number of satellites. In this paper, we firstly realize the PPP based on Beidou satellite navigation system(BDS). Secondly, we use the Helmet posteriori weighting method to establish a stochastic model, and set up a whole PPP system of GPS and BDS. By using the combined observations of BDS/GPS, the number of visible satellites is increased, which ameliorates the result of PPP in complex environments. The system is used to make a solution of PPP for eight observing stations distributed around the world. The result of PPP based on the ambiguity fixed solution is better than the result based on the ambiguity floating solution. Compared with single system PPP, dual-system PPP performs better in speed of convergence and accuracy of positioning. The error in the E and N directions is less than 1cm.