Research on an Active Hydrogen Maser Digital Circuit Control System Based on FPGA

Area of Science:

• Atomic, Molecular, and Optical Physics
• Precision Measurement and Metrology
• Aerospace Engineering and Technology

Background:

• Hydrogen masers are crucial for high-precision timekeeping in applications like satellite navigation.
• Active hydrogen masers (AHMs) offer superior stability over passive hydrogen masers (PHMs) but are larger and heavier.
• Reducing the size and weight of AHMs is essential for space-based applications.

Purpose of the Study:

• To develop a digital circuit control system for active hydrogen masers (AHMs) to reduce volume and weight.
• To improve the integration and flexibility of the maser's control circuitry.
• To enhance the frequency stability and reliability of AHMs for space applications.

Main Methods:

• Designed a digital control system utilizing a field-programmable gate array (FPGA).
• Implemented digital techniques for temperature control, signal detection, down-conversion, and phase-locking.
• Introduced a novel tuning method based on hydrogen flow to mitigate environmental frequency fluctuations.
• Validated the system's performance with oven-controlled crystal oscillator (OCXO) and cavity loops.

Main Results:

• The digital control system successfully met the performance requirements for both OCXO and cavity loops.
• Achieved remarkable frequency stability of 2.6×10⁻¹³/1 s and 1.4×10⁻¹⁵/10,000 s.
• The achieved stability is comparable to ground-based active hydrogen masers.

Conclusions:

• The developed FPGA-based digital control system offers a significant reduction in size and weight for AHMs.
• This technology provides a practical engineering solution for next-generation space navigation, deep space exploration, and space station timekeeping.
• The system's enhanced performance and miniaturization pave the way for more advanced space missions.