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Abstract The PPP-B2b service broadcasted by BDS-3 GEO satellites can provide centimeter to decimeter-level positioning accuracy in China and surrounding area. As a free satellite based-augmentation system, BDS PPP-B2b service also potentially benefits the low earth orbit (LEO) space users to improve the orbit determination accuracy. The challenge is the regional PPP-B2b augmentation information cannot cover the full orbit arc, so it has to switch the ephemeris datum between the PPP-B2b ephemeris and the broadcast ephemeris during the LEO precise orbit determination (POD). The PPP-B2b clock product is generated from a regional network, whose datum may not be consistency with the broadcast ephemeris, which hinders the seamless fusion between the PPP-B2b ephemeris and the broadcast ephemeris. In this study, we proposed a PPP-B2b enhanced model with hybrid LNAV/PPP-B2b clock offset datum transformation (CDT) and validated it with onboard GPS data from the GRACE satellites. Compared to the results using hybrid ephemeris without CDT, the results of reduced-dynamic and kinematic POD using the hybrid ephemeris reveal that the orbit accuracy with CDT is improved by 11.71% and 26.95% in 3D direction, and the LEO clock frequency stability with CDT is improved by 34.77% ~ 44.3% and 23.29% ~ 44.35% for different averaging times. The proposed CDT method achieves 2 decimeter accuracy in reduced-dynamic orbit and provides new application prospects for LEO POD based on regional PPP-B2b service.
Zhou et al. (Mon,) studied this question.