Abstract：This paper analyses the satellite clock correction principle of parameters with respect to GPS space-time reference points and deduces the BDS differential code bias (DCB) correction formula of single-frequency and dual-frequency ionospheric free combination in standard point position (SPP) and precise point position (PPP). With DCB files distributed by a multi-GNSS experiment (MGEX), some observation stations are calculated both in SPP and PPP. The results of BDS B1B3 and B1B2 dual-frequency SPP show that E direction improvement accuracy is at the sub-meter level, while N, U direction improvement accuracy are at the meter level. Moreover, before correction the position accuracy is extremely poor, with poorer accuracy of dual-frequency positioning compared to single-frequency positioning in E, N direction. From the results in BDS precise positioning, solutions in B1B3, in combination with DCB corrections, are very consistent with the B1B2 combination, and accuracy is improved in static and kinematic modes.
