LOOPBACK CONTROL SYSTEM IN DATA TRANSMISSION

摘要

PURPOSE:To attain switching by electric components in case of the optical fiber transmission by switching the transmission line not by a transmission line part but by the inside of a station. CONSTITUTION:If a station ST2 is faulty completely, a signal from the station ST2 is lost at a main transmission line side and a detector DT1 of a station ST3 has no signal and its output is 0. Thus, a changeover switch S1 is turned on to the position of a repeater RP and a switch S4 is turned off. As a result, a station ST3 is connected by the path of sub-transmission line R2 S2 RP TM D1 main transmission line. The switch S4 is turned off and no signal is transmitted to the station ST2. The detector DT2 of the station ST1 has no signal and then the changeover switch S2 is turned on to the position of a transmitter TM. As a result, the station ST1 is connected in the path of main transmission line R1 S1 TM S2 RP S4 D2 sub-transmission line. Then only the station ST2 is disconnected and the loop back is established.