A Space System for High-Accuracy Global Time and Frequency Comparison of Clocks

R. Decher, D.W. Allan, C.O. Alley, R.F.C. Vessot, G.M.R. Winkler

Abstract:	NASA is planning a Space Shuttle experiment to demonstrate high-accuracy global time and frequency transfer. A hydrogen maser clock on hoard the Space Shuttle will be compared with clocks on the ground using two-way microwave and short-pulse laser signals. The accuracy goal for the experiments 1 sec or better for the time transfer and 10-14 for the frequency comparison. A direct, frequency comparison of primary standards at the 1914 accuracy level is a unique feature of the proposed system. Roth time and frequency transfer will be accomplished by microwave transmission, while the laser signals provide calibration of the system as well as sub-nanosecond time transfer. Following the demonstration with the Space Shuttle, an operational system could be implemented in a free-flying satellite to provide permanent global time and frequency transfer.
Published in:	Proceedings of the 12th Annual Precise Time and Time Interval Systems and Applications Meeting December 2 - 4, 1980 Goddard Space Flight Center Greenbelt, Maryland
Pages:	99 - 111
Cite this article:	Decher, R., Allan, D.W., Alley, C.O., Vessot, R.F.C., Winkler, G.M.R., "A Space System for High-Accuracy Global Time and Frequency Comparison of Clocks," Proceedings of the 12th Annual Precise Time and Time Interval Systems and Applications Meeting, Greenbelt, Maryland, December 1980, pp. 99-111.
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