| 摘要 |
PURPOSE:To detect an interrupted transmission line with an intermediate repeater only by providing a bit representing the presence of insertion of alarm information for each intermediate repeater only to an alarm signal representing a defect and detecting the interruption fault of the transmission line while monitoring the bit. CONSTITUTION:An optoelectric conversion circuit 14 extracts an optical signal 201 passing through a optical directional coupler 13 in an intermediate repeater 2 as an electric signal 202. An ID bit 24 for station identification is provided to an OLTM as an alarm signal in a terminal station repeater. Moreover, a D(Drop)/I(Insert) FAIL bit 25 designating the presence of alarm insertion is provided to each OREP forming alarm information 23 in n-set of intermediate repeaters. Each intermediate repeater and terminal station repeater monitor the D/I FAIL bit 25 to confirm the presence of the insertion of alarm information in each intermediate repeater. |
