OPTICAL TRANSMISSION SYSTEM AND STATION DEVICE

PROBLEM TO BE SOLVED: To change an amount of the attenuation of an optical level of an optical signal transmitted from an OLT depending on a change in the number of branches of an optical coupler. SOLUTION: In an optical transmission system in which a plurality of subscriber terminal devices 2 are connected via an optical branching device 3 to a station device 1, the station device includes an optical transmitter/receiver 8 which transmits and receives an optical signal to and from the subscriber terminal devices, a variable attenuator 9 which attenuates the optical level of the optical signal transmitted from the optical transmitter/receiver, and an attenuation amount controller 10 which sets the amount of the attenuation of the optical level by the variable attenuator depending on the number of branches of the optical branching device. COPYRIGHT: (C)2011,JPO&INPIT