FREQUENCY STANDARDS WORK AND TIMEKEEPING AT THE NATIONAL RESEARCH COUNCIL OF CANADA

C.C. Costain, R.J. Douglas, C. Jacques, D. Morris, P. Tremblay, J. Vanier

Abstract:	For many years, the primary means of establishing the international time scale TAI was through the Loran C navigation network. When the East Coast network was reconfigured in 1979, with the introduction of Senece as the master of the North East Coast chain, it had some rather surprising effects on international time keeping. In Ottawa we found that the time of arrival of signals received from Nantucket and Seneca showed a seasonal variation of over 1 psl. This is the result of changes in propagation delay, and the changes introduced in the emission times of the Loran C stations by the local area monitor at Sandy Hook. Our path to Seneca is short and much over water, while the path to Nantucket is over the Adirondacks. For USNO the reverse is true, and when the USNO started reporting Seneca in mid 1979, a large seasonal variation was introduced into their time scale, and because of their weight of clocks, into TAI. In Figure 1, it can be seen that the time scales of NRC and PTB have a strongly correlated seasonal variation, in opposite phase to that of the USNO, which is an indication that the observed seasonal variation was in TAI.
Published in:	Proceedings of the 18th Annual Precise Time and Time Interval Systems and Applications Meeting December 2 - 4, 1986 DuPont Plaza Hotel Washington, DC
Pages:	71 - 77
Cite this article:	Costain, C.C., Douglas, R.J., Jacques, C., Morris, D., Tremblay, P., Vanier, J., "FREQUENCY STANDARDS WORK AND TIMEKEEPING AT THE NATIONAL RESEARCH COUNCIL OF CANADA," Proceedings of the 18th Annual Precise Time and Time Interval Systems and Applications Meeting, Washington, DC, December 1986, pp. 71-77.
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