Fiber optic RF frequency transfer on the distance of 480 km with the active stabilization of the propagation delay

In the paper the results of laboratory experiments are presented concerning the time and frequency transfer in 480 km long electronically stabilized fiber optic link. The fiber optic link comprised nine spooled spans with attenuation between 5–15 dB and eight custom-built bidirectional fiber amplifiers. The Allan deviation measured for frequency transfer at one-day averaging was around 4·10⁻¹⁷, whereas time deviation for 1PPS signal was in the range 650–900 fs for averaging times between 10³–10⁵ s.