Real-time performance monitoring of fiber optic long-distance time and RF frequency transfer links

In a long-distance fiber optic time and frequency distribution link, operating bi-directionally over a single fiber, gains of the optical amplifiers must be judiciously chosen to minimize various undesirable effects resulting from backscattered signals and other sources of noise. In this paper we propose to monitor the performance of the link continuously during its operation and to use these information for a real-time optimization of the parameters of transferred time and frequency signals. The design of the subsystem intended to measure the jitter of the frequency signal is discussed together with the evaluation results.