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

Area of Science:

• * Physics
• * Electrical Engineering
• * Metrology

Background:

• * Traditional atomic clocks like cesium and hydrogen masers offer excellent long-term and mid-term stability, respectively.
• * Voltage-controlled oscillators (VCOs) provide superior short-term stability but drift over longer periods.
• * Integrating these distinct clock types presents a challenge in achieving a unified, high-performance timing standard.

Purpose of the Study:

• * To develop a composite clock system that merges the stability advantages of cesium, hydrogen maser, and VCOs.
• * To design a control system capable of dynamically transferring the best available clock stability to the output signal.
• * To achieve a target relative instability of approximately 10⁻¹⁴ at 1 second, 10⁻¹⁵ at 10³ seconds, and 10⁻¹⁴ at 10⁶ seconds at 100 MHz.

Main Methods:

• * Implementation of a composite clock architecture integrating cesium, hydrogen maser, and VCO technologies.
• * Development of a digital Phase-Locked Loop (PLL) control system utilizing two references.
• * The control system is engineered to leverage the optimal stability from the master clocks at different averaging times.

Main Results:

• * The composite clock system demonstrates the potential to achieve high levels of stability across various timescales.
• * The control system effectively transfers the stability characteristics of the most stable master clock to the VCO.
• * Projected performance includes relative instability of ~10⁻¹⁴ at 1s, ~10⁻¹⁵ at 10³s, and ~10⁻¹⁴ at 10⁶s.

Conclusions:

• * The composite clock design successfully combines the strengths of different timing technologies.
• * The digital PLL control system is effective in optimizing clock stability across diverse averaging times.
• * This approach offers a promising pathway for creating advanced, high-stability frequency standards for demanding applications.