Real time clock synchronization

Abstract

A method of synchronizing a digital timer with the frequency of a source of A.C. power to provide long term temporal stability. The timer produces internal, fine resolution, synchronization and real time timing signals from a source of clock signals. The periods of all the timer produced timing signals are integral multiples of the period of its internal timing signal. A.C. reference timing signals which are a function of the frequency of the source of A.C. power are applied to the timer. The quotient of the period of the synchronization timing signals by that of the A.C. reference timing signals is an integer 'n'. Once n is determined, the number of fine resolution timing signals in each synchronization period for every n.sup.th A.C. timing signal is compared with a reference value. The timing of the fine resolution timing signals is adjusted to maintain the number of fine resolution timing signals in each synchronization period at which the n.sup.th A.C. reference timing signal is produced substantially equal to the reference value.