Time Transfer from Combined Analysis of GPS and TWSTFT Data

Pascale Defraigne, M. Carmen Martínez, and Z. Jiang

Abstract:	This paper presents the time transfer results obtained from the combination of GPS data and TWSTFT data. Two different methods are used for the combination: a first one (named CV+TW) is based on a least-squares analysis of GPS code and carrier-phase measurements in common view, constrained by TWSTFT data. Using the Vondrak-Cepek algorithm, the second approach (named PPP+TW) combines the TWSTFT time transfer data with the GPS clock solutions computed with Precise Point Positioning. Combining GPS and TWSTFT considerably increases the robustness of the accurate time transfer result due to the complete independence between the two spatial techniques. Both combination methods provide a time transfer solution which benefits from the high short-term stability and high resolution of the GPS data and the high accuracy of the TWSTFT data. The PPP+TW solution is continuous, while some discontinuities exist in the solution CV+TW, due to the noise and diurnal perturbation in the TW data. In general, the solutions obtained with both methods agree well with each other. The r.m.s. of the differences between the results remains below 300 picoseconds for the links investigated.
Published in:	Proceedings of the 40th Annual Precise Time and Time Interval Systems and Applications Meeting December 1 - 4, 2008 Hyatt Regency Reston Town Center Reston, Virginia
Pages:	565 - 576
Cite this article:	Defraigne, Pascale, Martínez, M. Carmen, Jiang, Z., "Time Transfer from Combined Analysis of GPS and TWSTFT Data," Proceedings of the 40th Annual Precise Time and Time Interval Systems and Applications Meeting, Reston, Virginia, December 2008, pp. 565-576.
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