BDS Differential Code Bias Estimation Using BeiDou Experimental Tracking Stations

Differential Code Biases (DCBs) are the main systematic error in ionosphere TEC monitoring and modeling. Meanwhile, satellite DCBs are important parameters for satellite navigation messaging. This article presents a satellite DCBs estimation algorithm and DCBs transformation formula derived under different zero-mean conditions as applied to the constellation average of the satellite DCBs. Using BeiDou Experimental Tracking Station (BETS) observations from 2013, the DCBs for BDS satellite were determined, and the BDS satellite DCBs monthly stability was analyzed and compared with the DCBs products published by MGEX under the same zero-mean conditions. Results show that the BDS satellite B1-B2 DCBs values are between-9~17 ns, and the stability was better than 0.4 ns. Stability for BDS IGSO satellites was better than GEO and MEO satellites. The BDS satellite DCBs determined using BETS and MGEX have system biases, where the largest discrepancy was about 1.7 ns. The probable reason lies in a discrepancy in the pseudo range code measurement. The difference of receiver material results in a discrepancy in receiver DCBs.