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

We present the project of a composite clock, that will combine a cesium standard, a hydrogen maser standard, and a voltage controlled oscillator in order to provide an output signal that would combine the respective quality of each of the component clocks, the long-term stability for the Cs clock, the mid-term stability for the H-maser and the the short-term performance for the VCO. The output signal is provided by the VCO. Design, advances in its realizations and alternative ways that have been considered concerning its different parts are presented. The objective is a relative frequency instability around 10^-15 over 1 s.