Precise Time Dissemination Via Portable Atomic Clocks

Kenneth Putkovich

Abstract:	The most precise operational method of time dissemination over long distances presently available to the Precise Time and Time Interval (PTTI) community of users is by means or portable atomic clocks. The many attempts that have been made in the past to devise operational systems for sub-microsecond time dissemination to supplant portable clocks largely have been unsuccessful. Many excellent techniques have been developed which are capable of the required precision. In some cases, the cost and burden of utilizing these techniques in a worldwide, operational time dissemination network have proved to be far greater than the portable clock costs. In other cases, the geographical coverage has been limited. In many cases, however, the managers of systems capable of being economically utilized for PTTI dissemination have been reluctant and, in some cases, adamantly opposed to even considering use of their systems for PTTI. In no case have the proposals for a system or a system modification solely for PTTI dissemination been seriously considered. The Global Positioning System (GPS) is the latest system showing promise of replacing portable clocks for global PTTI dissemination. Although GPS has the technical capability of providing superior world-wide dissemination, the question of present cost and future accessibility may require a continued reliance on portable clocks for a number of years. For these reasons it was felt that a discussion of portable clock operations as they are carried out today would be of some value. This paper describes the portable clock system that has been utilized by the U. S. Naval Observatory (NAVORSY) in the global synchronization of clocks over the past 17 years, explains the concepts on which it is based and examines some of its capabilities and limitations.
Published in:	Proceedings of the 13th Annual Precise Time and Time Interval Systems and Applications Meeting December 1 - 3, 1981 Naval Research Laboratory Washington, DC
Pages:	87 - 120
Cite this article:	Putkovich, Kenneth, "Precise Time Dissemination Via Portable Atomic Clocks," Proceedings of the 13th Annual Precise Time and Time Interval Systems and Applications Meeting, Washington, DC, December 1981, pp. 87-120.
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