Time Maintenance of User Clocks Via the Tracking and Data Relay Satellite System

Gary Whitworth, J.W. McIntyre, R.E. Dovas

Abstract:	During the 1980's, all NASA-supported low earth orbital spacecraft will be supported by the Tracking Data and Relay Satellite System (TDRSS). User spacecraft will have the capability of time-tagging science and housekeeping data on board the spacecraft. This activity requires that the on-board time scale be relatable to a standard time scale such as Universal Time Coordinated (UTC). A system is described which uses the TDRSS itself to compare the user satellite clock with a clock at the White Sands station that is referenced to UTC. No command of the spacecraft by the system is required, and actual on-board clock corrections are made by the spacecraft control center at its discretion. Computer models were constructed using basic orbital parameters for user and TDRS satellites. With only first-order corrections and simple averaging techniques for constant clock rates, error measurement precision of better than one microsecond was obtained. More sophisticated computations should allow considerable improvement over this
Published in:	Proceedings of the 14th Annual Precise Time and Time Interval Systems and Applications Meeting November 30 - 3, 1982 NASA Goddard Space Flight Center Greenbelt, Maryland
Pages:	39 - 56
Cite this article:	Whitworth, Gary, McIntyre, J.W., Dovas, R.E., "Time Maintenance of User Clocks Via the Tracking and Data Relay Satellite System," Proceedings of the 14th Annual Precise Time and Time Interval Systems and Applications Meeting, Greenbelt, Maryland, November 1982, pp. 39-56.
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