Passive Hydrogen Maser
PHM is an atomic clock used for precise positioning, timekeeping and other onboard applications. Designed to operate in space for more than 12 years, it offers an outstanding stability for averaging times from 1 to 100,000 seconds. The company is also developing a mini PHM, which offers the same frequency stability as the PHM in a smaller package.
The PHM clock consists of two modules, named Electronic Package and Physics Package respectively. Its operating principle is based on the stimulated microwave emission at the frequency of 1420.4 MHz, generated by the decay of the hydrogen atoms inside the microwave cavity of the Physics Package.