Composite clock including a Cs clock, a H-maser clock and a VCO.

This article presents the project of creating a composite clock, the advances in its realization and the technical choices. The goal is to generate an output signal which combines the advantages of each clock, the long-term stability for the cesium clock, the midterm stability for the hydrogen maser clock and short-term stability for the VCO. The control system must keep the stability of the best clock within each duration range. This system is designed for reaching a relative instability of some 10^-14 @ 1 s, 10^-15 @ 10³ s and 10^-14 @ 10⁶ s at 100 MHz, depending on the stability of the master clocks.