Title: High Availability of Real-time PPP by Extending SSR Orbit and Clock Corrections
Author(s): Hongzhou Yang
Published in: Proceedings of the 30th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS+ 2017)
September 25 - 29, 2017
Oregon Convention Center
Portland, Oregon
Pages: 4011 - 4025
Cite this article: Yang, Hongzhou, "High Availability of Real-time PPP by Extending SSR Orbit and Clock Corrections," Proceedings of the 30th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS+ 2017), Portland, Oregon, September 2017, pp. 4011-4025.
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Abstract: *ION GNSS+ 2017 Student Paper Award Winner* High availability of real-time PPP services requires high availability of precise orbit and clock corrections. To meet the rapidly increasing demand from the real-time PPP users, IGS Real-Time Service (RTS) is currently disseminating several real-time high-frequency State Space Representation (SSR) products through Internet under the Networked Transport of RTCM via Internet Protocol (NTRIP) protocol. But any correction outage, either due to corrupted ephemeris or loss of communication link, will degrade the availability of precise positioning using the service. To tackle the above problem, an extension of the existing SSR message package is proposed. In the new package, Solar Radiation Parameters (SRP) for satellite orbit and periodical terms for satellite clock offsets will be added to supplement the existing SSR orbit and clock corrections. After extension of the existing SSR message package, continuous precise satellite orbit and clock corrections will be available during correction outages using a method proposed in Gao et al. (2016a, 2016b). In other words, real-time users can generate their own precise orbit and clock corrections with the help of the available SRP and periodical terms whenever a correction service outage occurs. The update intervals for the SRP and periodical terms can be at very low frequency, e.g. once two hours, which is advantageous for real-time PPP applications. With the new SSR message package, the dependence of high availability of precise orbit and clock corrections on the communication link is greatly undermined, hence the availability of real-time PPP increases correspondingly. To validate the extended SSR message package, its performance will be compared to the case using the existing SSR message package for both the situations when the communication link is on and lost. Field test results will also be presented using real-time extended SSR message package. Results have shown significantly improved availability of real-time PPP by adopting the newly proposed SSR message package. Apart from that, for real-time PPP users tend to receive the new extended SSR message package, they also have the option to receive the package with lower frequency so long as the positioning precision meets their requirements.