Composite clock including a Cs clock, an H-Maser clock, and a voltage-controlled oscillator

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 mid-term stability for the hydrogen maser clock, and the short-term stability for the voltage-controlled oscillator (VCO). The control system is designed to transfer the stability of the best clock at a given averaging time to the VCO. This system is designed to reach a relative instability of approximately 10^-14 at 1 s, 10^-15 at 10³ s, and 10^-14 at 10⁶ s at 100 MHz, depending on the stability of the master clocks. To make this composite clock, we use a digital PLL with 2 references.