Redundant frequency source with seamless switchover

This paper describes a redundant frequency source system with seamless switchover that produces a stable and continuous output frequency signal. This system has primary and backup frequency produce links to generate the reference frequency. It has the ability to monitor the integrity of the frequency produce links and switchover seamlessly between the primary and the backup links. By use intermediate oscillator of the measurement system as a third party criterion, the autonomous monitor integrity of frequency produce links was achieved without external reference signal. The excellent short-term stability characteristics of intermediate oscillator improves the accuracy and real-time for the monitoring of sudden failure and the degradation of performance. Seamless switchover was defined as the maintenance of both output phase and frequency continuity while and after the switcher from the primary to the backup links. It was initiated when system detects a degradation of the integrity of primary links. The experiment result has been presented showing that there were no detectable change in phase and frequency after the switchover, and the jump of frequency was less than 2e-13, the change of phase less than 100ps.