Real-time clock bias estimation evaluation based on BeiDou PPP-B2b and Galileo high accuracy service

In response to the limited number of satellites available for precise point positioning (PPP) at the same time with BeiDou Navigation Satelliee System (BDS) PPP-B2b and the lack of research on real-time clock offset estimation, an improved method based on the fusion of BDS PPP-B2b and Galileo high accuracy service (HAS) is proposed, and its real-time clock bias estimation performance is systematically evaluated. The method fuses the PPP state space representation (SSR) corrections from both satellite systems, significantly increasing the number of satellites available at the same epoch. Compared to the standalone PPP-B2b service, this approach demonstrates substantial improvements in the accuracy and stability of clock bias estimation. Experimental results show that, after a certain period of convergence, the method outperforms the ultra-fast (UTL) product provided by GFZ. Therefore, this work not only provides an effective way to enhance the practical application of PPP-B2b services but also offers new insights and experimental validation for the design and performance optimization of real-time time solutions in multi-system integration.