## 4 Results
### PPP Time Transfer in the Kinematic Model Using HAS Service
Figures 14 and 15 depict the outcomes of the GPS PPP time transfer, facilitated by the Galileo HAS service, in kinematic mode across six time links, as well as the time transfer results for Galileo and the integrated Galileo/GPS PPP in kinematic mode across the same six time links. Upon examining the data presented in the two figures, several noteworthy observations emerge. Firstly, it becomes clear that the time transfer outcomes still exhibit instances of re-convergence, indicating that this phenomenon is not entirely mitigated. Secondly, aside from the TWTF-PTBB time link, the time transfer noise under the Galileo  
Figure 11: The receiver clock offset from GPS PPP in the kinematic model for six stations. PPP kinematic mode is observed to be less pronounced compared to the GPS PPP across the remaining links, suggesting a certain level of superiority in noise management. Lastly, while the Galileo/GPS combined PPP demonstrates the most favorable performance in kinematic conditions, there is a noticeable increase in time transfer noise when compared to the static model, highlighting a persistent challenge in the kinematic environments. Figure 12: Galileo\(\backslash\)GPS PPP in the kinematic model for PTBB station. Figure 13: Galileo/GPS or Galileo PPP in the kinematic model for six stations. To assess the performance of PPP time transfer under kinematic conditions enabled by the Galileo HAS, Table 5 details the standard deviations of the deviations from the reference values for GPS, Galileo, and the combined Galileo/GPS PPP time transfer in dynamic scenarios. Furthermore, Figure 16 depicts the MDEV values for six time links, showcasing their stability in the kinematic PPP operational model. Upon examining the data presented, it is evident that the precision of single-constellation PPP time transfer, either using GPS or Galileo, in kinematic conditions is adversely affected by the amplification of noise and the challenges associated with re-convergence, resulting in accuracies that can exceed 1 nanosecond. This degradation in precision is largely attributed to the frequent re-convergence events. However, it is noteworthy that time links with less frequent re-convergence instances, such as the BRUX-PTBB link, continue to deliver sub-nanosecond time transfer performance in the kinematic model. Fortunately, the combined Galileo/GPS PPP approach maintains the ability to achieve sub-nanosecond accuracy (with an average STD value of 0.48 ns) across all time links, even under kinematic conditions. This performance is on par with the static PPP time transfer, demonstrating the robustness and reliability of the Galileo/GPS PPP integration in maintaining high-precision time synchronization. Figure 14: GPS PPP time transfer in the kinematic model for six time links. To delve deeper into the analysis of the frequency stability of the PPP time transfer based on the Galileo HAS service under kinematic conditions, Figure 16 illustrates the MDEV for various time links across different system configurations. Concurrently, Table 6 presents the frequency stability for the same links under the same system combinations, measured over intervals of 960 s and 15,360 s.  
Upon a comprehensive review, it is observed that, with the exception of the TWTF-PTBB link, the GPS PPP exhibits a higher MDEV in kinematic mode compared to Galileo PPP. Moreover, the integrated Galileo/GPS PPP demonstrates a markedly superior frequency stability over any single-system PPP time transfer in kinematic conditions. At the 960 s frequency stability mark, the average Median Deviation (MDEV) for the distinct time links in the GPS, Galileo, and combined Galileo/GPS PPP solutions are 5.29 \(\times\) 10\({}^{-13}\), 3.34 \(\times\) 10\({}^{-13}\), and 1.60 \(\times\) 10\({}^{-13}\), respectively. Extending the observation to a 15,360 s frequency stability duration, the corresponding averages are 1.49 \(\times\) 10\({}^{-13}\), 1.02 \(\times\) 10\({}^{-13}\), and  
Figure 15: Galileo/GPS or Galileo PPP time transfer solutions in the kinematic model for six time links.