Observation Weight Function Design for Fusing BDS/GPS Data to Estimate the Real-time Clock with Regard to the Orbit Errors

The real-time clock product is one of the basis products for wide-area positioning service of high precision. Considering the difference between BDS orbit precision and GPS precision, we design a new observation weight function, in order to optimize the stochastic model of real time BDS/GPS clock estimation. The BDS/GPS observations of 78 MGEX global stations and 2 iGMAS stations were collected to generate the real time clock, and then the calculation results were compared with the final iGMAS precise clock product in two strategies (the old stochastic model and the new stochastic model). It shows that the method based the proposed stochastic model can improve the precision of satellite clock about 9% for GPS and 10% for BDS.