Multi-Channel GPS Common-View Time Transfer Experiments: First Results and Uncertainty Study for Short and Long Baselines

Gerard Petit, Claudine Thomas, Philippe Moussay, John A. Davis, Mihran Miranian, Juan Palacio

Abstract:	Far regular TAI computations, GPS time transfer is currently out using a number of common-view observations from single-channel single-frequency C/A code receivers operating in a scheduled mode. This mode of operation limits the accuracy of time transfer and serious problems of ageing of the current receivers are now being encountered. This paper considers all-in-view measurements from muIti-channel dual frequency GPS time receivers used to carry out time transfer between remote locations, taking into account all possible common-view observations for a given baseline. We have used data from Allen Osborne Associates TTR-4P receivers operating at the BIPM the NPL, the ROA and the USNO. Two approaches have been used. First we construct for each station, standard 13-minute common-view observations of all available satellites and use these data to compute time differences for three baselines. We find that the results are better than those obtained with singIe-channeI receivers, and are about in accord with what might be expected from the number of measurements. Second we use raw short-term data to compute time differences and compare the results with the standard approach for one baseline. We find that the raw data provide a better measurement of the time link than is possible using the standard approach. In all cases the equipment in use display large variations in the calibration delay that are likely to be induced by the enviroment and require a corrective action,
Published in:	Proceedings of the 29th Annual Precise Time and Time Interval Systems and Applications Meeting December 2 - 4, 1997 Sheraton Long Beach Hotel Long Beach, California
Pages:	309 - 318
Cite this article:	Petit, Gerard, Thomas, Claudine, Moussay, Philippe, Davis, John A., Miranian, Mihran, Palacio, Juan, "Multi-Channel GPS Common-View Time Transfer Experiments: First Results and Uncertainty Study for Short and Long Baselines," Proceedings of the 29th Annual Precise Time and Time Interval Systems and Applications Meeting, Long Beach, California, December 1997, pp. 309-318.
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