Control algorithm of UTC(MIKE)

The Finnish realization of coordinated universal time, designated UTC(MIKE), is derived from a single active hydrogen maser at the Centre for Metrology and Accreditation (MIKES). The frequency of a hydrogen maser typically drifts with time, leading to an approximately parabolic phase shift. At MIKES, a programmable delay generator is used to negate the phase drift of the maser. An improved control algorithm for the phase compensation has lead to a ten-fold improvement in time stability compared to our previous results. With time-transfer based on precise point positioning, we have been able to keep UTC(MIKE) within ±6 ns of UTC during the past year even though our only link to primary frequency standards is through the CCTF-K001. UTC and Circular T. Moreover, improved predictability has lowered the time deviation (TDEV) of UTC(MIKE) to a level below 500 ps when data from the past 10 months is considered.