Time Transfer from Combined Analysis of GPS and TWSTFT Data
ROYAL OBSERVATORY BRUSSELS (BELGIUM)
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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 CVTW 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 PPPTW 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 PPPTW solution is continuous, while some discontinuities exist in the solution CVTW, 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.
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