Estimation of the DCB for the BDS-3 new signals based on BDGIM constraints

Abstract

The hardware delay difference for different navigation signals in satellite or receiver channels is called Differential Code Bias (DCB). DCB is a major error of global navigation satellite system (GNSS), which may lead to tens of Total Electron Content unit (TECu) ionospheric delay errors or several-meter ranging errors. The basic system of BeiDou Navigation Satellite System has opened services and three new navigation signals, namely B1C, B2a at the end of 2018, and B2b at the end of 2019. As the BeiDou satellite broadcast clock difference is based on the phase center of the B3I signal antenna, it is necessary to estimated the DCB values of the new navigation signals relative to B3I. Considering that BDS broadcasts the BeiDou global ionospheric delay correction model (BDGIM) parameters with the highest precision, the method of solving satellite or receiver DCB based on the BDS-3 BDGIM parameter constraint is proposed and verified. Theoretical analysis shows that the mean square error of daily solution is about 0.63–1.96 ns. The measured data of 25 iGMAS stations from January 1 to 30, 2019, are used for verification. The results show that the solution precision of satellite DCB is better than 1.0 ns and that of receiver DCB is slightly worse. This method does not need the support of external ionospheric products and provides a possibility for online real-time estimating of the satellite and receiver DCB.