1.
IEEE Trans Ultrason Ferroelectr Freq Control
; 65(6): 898-903, 2018 06.
Article
in English
| MEDLINE
| ID: mdl-29856705
ABSTRACT
This paper gives a brief account of the history of time standards and timekeeping beginning with John Harrison's seagoing clocks for navigation up to today's optical frequency standards and prospects for the future definition of the second.
2.
IEEE Trans Ultrason Ferroelectr Freq Control
; 55(4): 750-60, 2008 Apr.
Article
in English
| MEDLINE
| ID: mdl-18467219
ABSTRACT
We refine our estimate of the uncertainty in [UTC - UTC(k)] by taking into account the contribution of correlations between the links. Using a matrix formulation to facilitate computation, we re-analyze the link-based uncertainties and obtain the same solution as found previously. We then evaluate the site-based uncertainties and compare the results with the link-based uncertainties.