Study of high-precision time transfer method enhanced by PPP-AR/PPP-RTK

With the ongoing advancements in the Global Navigation Satellite System (GNSS), the technology for high-precision time transfer facilitated by GNSS has also become increasingly refined. This paper aims to investigate the contribution of information-enhanced GNSS PPP to time transfer performance, with a focus on the comprehensive evaluation and analysis of the time transfer performance of PPP-AR and PPP-RTK. Using GPS as a case study, experimental results indicate that the average success fixing rate of PPP integer ambiguity resolution across five stations is 94%. Using the standard deviation for stability assessment, the analysis reveals that the stability of the station clock offset sequence of PPP-AR is superior to that of PPP floating solution. In comparison to the PPP floating solution, the average improvement of PPP-AR stability is 17%. Furthermore, using PPP-AR for time transfer improves the stability of the time transfer link clock offset sequence and also reduces its noise level. Moreover, different types of time transfer links exhibit varying degrees of improvement. The stability has been increased by 14% on average, and the noise level has been improved by 9% on average. Additionally,` the Allan deviation is employed to assess the frequency stability. The findings indicate that the frequency stability of the fixed solution is superior to that of the float solution. PPP-RTK also enhances the stability, noise level and frequency stability of time transfer even better than PPP-AR. Nevertheless, as the reference network scale increases, the accuracy of the interpolated atmospheric delay correction diminishes, impacting the performance of PPP-RTK.