Characterization of the frequency transfer over 300 km of aerial suspended fiber

In this paper we are reporting on the experiments with a 300-km-long suspended fiber running inside the safety wire of the power grid and being a part of large optical wavelength division multiplexing telecom network. We used this fiber to carry the 10 MHz frequency signal and investigated the influence of heavy environmental conditions on the stability of the transfer. We were able to find the evidence that the transmission in the aerial fiber is affected, apart from rapidly varying external temperature, by the wind and by the 50 Hz pickup from the power grid. However, the general result of our investigations is that the true stability-limiting factor is not the fiber and various environmental conditions, but the time-dependent asymmetry of the telecom equipment, like e.g. reconfigurable optical add-drop multiplexers.