GPS/GLONASS System Bias Estimation and Application in GPS/GLONASS Combined Positioning

摘要

Multi-GNSS data analysis has become a new challenge with the development of satellite navigation systems. System bias is the key issue in Multi-GNSS data analysis, which has no recommended models within IGS community. We introduce the integrated data analysis model developed at the GNSS data analysis center of Shanghai Astronomical Observatory (SHAO). Based on the routine GNSS data analysis at SHAO over 14 months, we analyze the precise GPS/GLONASS system bias product in detail. Results show: (1) system bias shows similarity for same type of receivers, while obvious difference are observed for different type of receivers; (2) variation of system bias shows same pattern for all stations, which indicates that the long-term variation of system bias is caused by the system time offset; (3) system bias is influenced also by type of antenna type. A model is derived to separate hardware delay difference (HDD) between GPS/GLONASS observations at the same receiver and the so-called inter-frequency bias (IFB). Analysis of the HDD and IFB time series shows that both terms are affected by the change of receiver type, antenna type, firmware series, cable type and length. Applying the system bias into PPP positioning, precision of GLONASS-only solution is improved by 55 % and precision of GPS/GLONASS combined solution is improved by 30 %.