GNSS System Time Offset Real-Time Monitoring with GLONASS ICBs Estimated

Global Navigation Satellite Systems (GNSS) include Global Positioning System (GPS), Global Navigation Satellite System (GLONASS), Galileo satellite navigation system (Galileo) and BeiDou Navigation Satellite System (BDS). With the development of BDS, it is necessary to monitor system time offset between BDS and the other GNSSs to enhance the compatibility and interoperability among GNSSs. The system time offset between GLONASS and BDS is affected by the inter-channel biases (ICBs) caused by frequency division multiple access technique (FDMA). To reduce the impact of GLONASS ICBs on BDS and GLONASS system time offset (BDS-GLONASS), this paper proposes a method of estimating GLONASS ICBs parameters and system time offset parameters in real time. The experimental results indicate that the standard deviation (STD) of BDS-GLONASS monitoring value can be reduced from 6 ~ 7ns to about 3ns (more than 45%). And the STD of BDS-GPS and BDS-Galileo monitoring value can be reduced more than 15%. This work will also lead to further research in GNSS system time offset monitoring and forecasting.