Real time realization of UTC at Paris Observatory

Rovera, Daniele

UTC(OP), the French national realization of the international Coordinated Universal Time, was redesigned and rebuilt. The first step was the implementation in October 2012 of a new algorithm based on a H-maser and on atomic fountain data. Thanks to the new implementation, the stability of UTC(OP) was dramatically improved and UTC(OP) competes with the best time scales available today. Then the hardware generating and distributing the UTC(OP) physical signals was replaced. Part of the new hardware is composed of commercial devices, but the key elements were specifically developed. One of them is a special switch that allows the UTC(OP) signals be derived from one of two time scales, based on two different H-masers, which are generated simultaneously. This insures the continuity of the UTC(OP) signal even when a change of the reference H-maser is required.

With the new hardware implementation, UTC(OP) is made available through three coherent signals: 100 MHz, 10 MHz and 1 PPS. The UTC(OP) signals are now fully compatible with the requirements of the ground terminals of the space mission Atomic Clock Ensemble in Space (ACES).

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