## 4 Conclusions  
Real-time orbits and clocks are crucial factors for RT-PPP applications. To evaluate the impacts of existing real-time orbit and clock products (BDS-3 PPP-Bb and IGS RTS), this study provides comprehensive assessments of the accuracy of these real-time products and their influences on the positioning accuracy and convergence time of RT-PPP in both static and dynamic tests. After the descriptions of the evaluation methods for real-time orbits and clocks as well as the real-time single-/dual-frequency PPP models, BDS-3 new signals observations of B1C and B2b from the four MEGX stations and a set of the vehicle-borne test were used to find the conclusions of the assessment. The main conclusions can be summarized as follows.  
For these real-time SSR products, the orbit accuracy of PPP-B2b SSR products is lower than these of IGS real-time products (CAS, DLR, GFZ, and WHU). However, the clock accuracy of PPP-B2b is better than these of IGS real-time products. Additionally, the accuracy of the real-time orbit and clock of BDS-3 provided by PPP-B2b is higher than that of GPS.  
For real-time dual-frequency PPP, the position RMSEs of the four MEGX stations based on PPP-B2b SSR products are slightly lower than those based on the IGS RTS SSR products. Meanwhile, the BDS-3 BII+B3I PPP positioning accuracy using the PPP-B2b service is centimeter-level which is better than that of GPS L1+L2 PPP. The dual-frequency B1I+B2b PPP positioning accuracy in the vehicle-borne test achieved submeter-level and meter-level in horizontal and vertical components in our test environment.  
For the single-frequency RT-PPP based on PPP-B2b SSR products, the BDS-3 BIC PPP is lower than that of B1I+B3I PPP, providing about 10-20 cm-level positioning accuracy with MEGX data. While using the vehicle-borne B2b frequency data, the accuracy of BDS-3 PPP is very close to that of B1I+B2b PPP with submeter-level and meter-level in horizontal and vertical components.  
In general, our work shows that both the BDS-3 PPP-B2b service and the IGS RTS can satisfy the demand for high-accuracy positioning in real time. However, these real-time products provided by IGS RTS are calculated from the global-distributed stations, which are more accurate than BDS-3 PPP-B2b, especially for GPS. However, IGS RTS are limited by the connection of the internet. Additionally, BDS-3 PPP-B2b introduces inter-satellite link technology and broadcasts SSR information by navigation signal, which gives it more significant potential in real-time precise positioning applications in the future.  
Conceptualization, C.Y., Y.Z. and Z.G.; Data curation, Q.X.; Funding acquisition, C.Y. and Z.G.; Investigation, R.L., C.Y. and Z.G.; Software, R.L.; Supervision, C.Y. and Z.G.; Visualization, R.L., Q.X. and J.L.; Writing--original draft, R.L.; Writing--review and editing, R.L., C.Y., Y.Z. and Z.G. All authors have read and agreed to the published version of the manuscript.  
This research was partly supported by the National Key Research and Development Program of China (Grant No. 2020 YFB0505802), the National Natural Science Foundation of China (NSFC) (Grants No. 42274022, No. 42274024).  
The datasets analyzed in this study are managed by the School of Land Science and Geomatics, China University of Geosciences, Beijing, and can be available on request from the corresponding author.  
Thanks to the original observations provided by MGEX and the multi-system SSR products provided by the analysis centers CAS, DLR, GFZ, and WHU.  
The authors declare no conflict of interest.