FCDP AND ACES CLOCK SIGNAL
The Frequency Comparison and Distribution Package (FCDP), developed by EADS under ESA responsibility, is the core of the atomic clock ensemble. PHARAO and SHM 100-MHz clock signals are delivered to the FCDP and their frequency and phase compared. Direct comparison of the two clocks has two purposes: to drive the short-term servo loop for phase-locking PHARAO’s local oscillator to the SHM, and to assess onboard clock stability. Finally, the FCDP distributes the ACES clock signal to the MWL.