Precision Clock

 
SELEX Galileo produce atomic clocks with outstanding stability for averaging times from 1 to 100.000 seconds, to be used in precise positioning, time keeping and other on-board applications. 

PHM - Passive Hydrogen MASER  PHM (Passive Hydrogen Maser) is an atomic clock designed to perform in the space environment for a minimum of 12 years. With outstanding stability for averaging times ranging 1 to 100,000 seconds, it is used in precise positioning and time keeping. PHM is flying with excellent performances on-board the GIOVE B Satellite and has been selected as the reference clock for the Galileo Constellation.