Algorithm for On-Orbit GPS III Clock Correction

John P. Janis and Michael R. Jones

Abstract:	The Atomic Frequency Standards in each GPS satellite form the basis for global navigation. As reported previously, the Rubidium Atomic Frequency Standards (RAFS) occasionally experience frequency and phase anomalies that impact operational availability and system performance. In GPS III currently, RAFS anomaly detection is based on fixed limits. When an anomaly is detected, the satellite is automatically switched to Non-Standard Code (NSC), requiring Control Segment intervention to resume standard code operation. We present the results of an advanced algorithm to automatically detect and correct for these anomalies. The algorithm employs adaptive thresholding to minimize time to correction for the largest anomalies while maximizing detection sensitivity and correction accuracy, taking advantage of the capabilities of the GPS III Navigation Payload TKS to simultaneously measure the phase of multiple onboard clocks.
Published in:	Proceedings of the 48th Annual Precise Time and Time Interval Systems and Applications Meeting January 30 - 2, 2017 Hyatt Regency Monterey Monterey, California
Pages:	177 - 182
Cite this article:	Janis, John P., Jones, Michael R., "Algorithm for On-Orbit GPS III Clock Correction," Proceedings of the 48th Annual Precise Time and Time Interval Systems and Applications Meeting, Monterey, California, January 2017, pp. 177-182. https://doi.org/10.33012/2017.14985
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