Airbus Defence and Space


Clock monitor & control unit

The CMCU is a high performance 10.23 MHz master clock generation unit for satellite navigation systems. Two frequency synthesizers can select independently one out of four signal inputs to which independent 10 MHz atomic clock frequency references can be provided as a basis for the master clock generation. One of the two synthesizer outputs is selected to provide the master clock for the payload and is distributed to up to four identical outputs. The output signal of the second synthesizer provides a hot redundant alternative for the master clock. A phase meter monitors the output phase of the active synthesizer against the hot redundant one. To increase the operational safety the CMCU abandons a micro controller use. The TM/TC interface is implemented as hard wired logic and can be addressed by serial and high level commands. According to the customer needs optional features like phase synchronous output switching between active and redundant synthesizer, parameter based clock drift compensation or synthesizer adaptation to source characteristics can be implemented.

Features / technical details

• Master Timing Reference generation (10.23MHz) for NAV payloads

• Direct Digital Frequency Synthesis with hyper-fine tuning steps to correct frequency drifts of atomic clocks while not degrading their performance

• Frequency Comparison System determines drifts between two atomic clocks

• Frequency distribution networks

• High phase stability over temperature drifts

• 4 x 2 switch matrix with high isolation to prevent degradation of clock stability



• Navigation Payloads (global or regional)

• High-performance Communication Systems

• Scientific Applications

• Pseudolite Systems