| 摘要 |
PROBLEM TO BE SOLVED: To provide a fault detector and method for transmission line that can correctly and economically detect a fault in a transmission line while keeping the economy, availability and high reliability of a communication system where two-way optical communication is conducted between one device and a plurality of devices. SOLUTION: In the system where two-way optical communication is conducted between a station side device and a plurality of subscriber devices that are branch-connected to the station side device by a branching coupler, a monitor is connected between the station side device and the branching coupler, an attenuator is provided for each of a plurality of optical transmission liens between the branching coupler and the subscriber devices, the monitor transmits a test optical signal and monitors a reflection signal of the test signal that is reflected and returned and its attenuation state while monitoring the presence of the attenuation of each attenuator or changing the attenuation so as to locate a faulty transmission line among a plurality of the optical transmission lines and a distance of a faulty point. |
