A Real-Time Clock Offset Datum Maintenance Method Based on Short-Term Clock Offset Prediction

Jianhua Cheng, Xue Liu, Hui Li, Nan Li, WenZhen Peng

Abstract:	Real-time precise satellite clock offset product is widely used in real-time precise point positioning (PPP) and real-time satellite clock performance monitoring. However, affected by the real-time observation outliers or outages, the disruption in clock offset datum constructed by a receiver clock is inevitable. In this paper, a real-time clock offset datum maintenance method based on short-term clock offset prediction is proposed. This method first selects the satellite clock with the best frequency stability for clock offset short-term prediction based on historical estimated satellite clock offsets, and then sets the selected satellite clock offset to predicted value as constraint to maintain the original clock offset datum during the clock offset datum interruption. The proposed method is compared with the conventional clock offset datum switching method and the situation without clock offset datum switching. The results show that the clock offset estimated accuracy of the proposed method is equivalent to accuracy without datum switching. The clock offset datum maintenance accuracy of the conventional method and the proposed method are 169.68 ns and 0.07 ns, respectively. The satellite clock frequency stability of the proposed method and the situation without clock offset datum switching are almost identical at the averaging interval from 100 to 10000 s. The PPP experiment using the clock offsets obtained with the proposed method shows that the positioning RMS in north, east and up are 3.7, 6.5, and 8.4 cm, respectively. Besides, the positioning fluctuations and re-convergence can be avoided effectively. Therefore, compared with the conventional clock offset datum switching method, the proposed method can effectively guarantee the continuity and consistency of the clock offset datum during the interruption of clock offset datum.
Published in:	Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023) September 11 - 15, 2023 Hyatt Regency Denver Denver, Colorado
Pages:	800 - 814
Cite this article:	Cheng, Jianhua, Liu, Xue, Li, Hui, Li, Nan, Peng, WenZhen, "A Real-Time Clock Offset Datum Maintenance Method Based on Short-Term Clock Offset Prediction," Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023), Denver, Colorado, September 2023, pp. 800-814. https://doi.org/10.33012/2023.19359
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