RESUMO
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.
RESUMO
This article reviews the creation and technical evolution of atomic time scales. In particular, we focus our attention on the method of calculation and the characteristics of International Atomic Time (TAI), and show how it is disseminated at the ultimate level of precision.
Assuntos
Sistema Internacional de Unidades/normas , Internacionalidade , Oscilometria/normas , Fatores de Tempo , Padrões de ReferênciaRESUMO
A new algorithm for the clock frequency prediction used to calculate the Echelle Atomique Libre (EAL) is presented. The mathematical model adopted in the new prediction algorithm takes into account the effect of the frequency drift of the H-masers. We demonstrate that there is an improvement in long-term stability of EAL by using the new prediction algorithm.
