In PTB’s wide spectrum of tasks, dissemination of legal time is one of the most important service tasks performed for the public. Whereas atomic clocks a priori furnish only time intervals of extremely precise duration, the realization and the dissemination of legal time require a comparison and combination of the signals of the different PTB clocks. Moreover, the second marks must be brought into a well-defined relation to the international time system. This purpose serve international time and frequency comparisons via GPS and telecommunication satellites. The finally obtained national reference time scale UTC(PTB) forms the basis of legal time which is thus realized in a cooperation between PTB working groups “Time Standards” (4.41) and “Transmission of Time” (4.42).

• PTB-Mitteilung: Die SI-Basiseinheit "Sekunde"