| 摘要 |
A bi-directional system which reduces the number of wavelength for downward and upward signals and monitors any malfunction of repeaters accurately. The system of the present invention comprises end terminals for transmitting/receiving light signals, optical fibers for upward/downward transmission line which carry the light signal, and a plurality of optical repeaters which amplify directly the attenuated light signals. Here, each repeater comprises an optical amplifier for the transmission lines, an optical coupler for separating the output of the optical amplifier into two beams, and optical filter for extracting monitor wavelength to output it into the opposite direction. Any faulty repeater is detected by analyzing the amplitudes of the pulse train which returns back to an end terminal under the time delay depending upon the distance between the end terminal and each repeater. <IMAGE> |
