SATELLITE TWO-WAY TIME TRANSFER: FUNDAMENTALS AND RECENT PROGRESS

D.A. Howe, D.W. Hanson, J.L. Jesperscn, M.A. Lombardi

Abstract: Experiments in precise clock comparisons using the two-way time transfer technique via satellite began in 1962. Experience gained from a variety of experiments since that time steadily improved the precision and accuracy of such comparisons. Recent growth in the fixed satellite service, or FSs, has created new opportunities at moderate costs for high-accuracy time transfers using geostationary satellites. We discuss fundamental aspects of two-way timing and show an implementation of a satellite two-way time transfer system which has been used for two-years between USNO, Washington, D.C. and NIST, Boulder, Co. The raw data collection procedure will be discussed. We also outline the rationale for the choice of satellite uplink/downlink frequencies, signal structure, and reduction of data. Short-term noise in the time transfer limits the precision to about 300 px in a 300 average. Uncertainty in accuracy is due to uncertainty in the non-reciprocity of the two-way signal path. Accuracy limits due to the atmosphere, earth-satellite rotating system (Sagnac effect), and the equipment are discussed. The goal is to achieve an accuracy level of ins after a suitable calibration of earth-station (differential) equipment delays. Satellite Two-way Time Transfer We discuss fundamental aspects of two-way time transfers first.
Published in: Proceedings of the 21th Annual Precise Time and Time Interval Systems and Applications Meeting
November 28 - 30, 1989
Sheraton Hotel
Redondo Beach, California
Pages: 117 - 130
Cite this article: Howe, D.A., Hanson, D.W., Jesperscn, J.L., Lombardi, M.A., "SATELLITE TWO-WAY TIME TRANSFER: FUNDAMENTALS AND RECENT PROGRESS," Proceedings of the 21th Annual Precise Time and Time Interval Systems and Applications Meeting, Redondo Beach, California, November 1989, pp. 117-130.
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