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Abstract:
Precise orbit products are fundamental for real-time Global Navigation Satellite Systems (GNSS) applications. Currently, the ultra-rapid orbits are provided via batch processing and predicted over a certain period at most of the IGS Analysis Centers. As the orbit accuracy degrades along with the prediction time, especially for satellites in eclipse, reducing orbit update latency becomes increasingly important but is very challenging due to the multi-GNSS constellation with about 130 satellites. In this study, a new ultra-rapid obit processing strategy is proposed to realize orbit update every hour or even half-hour for integrated processing of all GNSS and QZSS satellites. By utilizing information of previously processed sessions, only the most recent (sub-)hourly observations are processed with undifferenced ambiguity resolution. Through a rigorous combination approach of the historic and the recent (sub-)hourly information equivalent solutions to that of the 24/48-hour session are achieved. With the proposed strategy, a latency of 30-min is available and ensures that the accuracy of the real-time available orbits is improved to 3.5 cm, 10.2 cm, 3.9 cm and 7.2 cm for GPS, GLONASS, Galileo and BDS, respectively, which is around 6.5%-22% better than the 2-hour updated orbits.
