Passive Hydrogen Maser (PHM) and Rubidium Atomic Frequency Standard (RAFS) are the two baseline on-board clock technologies for Galileo, the European Global Navigation Satellite System (GNSS), which are currently being validated on-board two experimental spacecrafts, GIOVE-A and GIOVE-B. These two spacecrafts are orbiting in a Galileo-representative orbit and transmit Galileo representative signals that are tracked and collected by a network of evenly distributed sensor stations (the Galileo Experimental Sensor Stations). The collected observables (pseudo-range and carrier phase) are being processed by the GIOVE Processing Centre, providing as one of its core product the estimation of the phase offset between the on-board clock and a reference clock, chosen to be an Active Hydrogen Maser connected to one of the sensor stations. Read More
