| 摘要 |
PURPOSE:To simplify a circuit constitution while a loop pack is composed of four gates with ascending and descending regenerative repeaters by providing a gate to NRZ/RZ-convert commonly to a main signal system and a loop-back system. CONSTITUTION:A main signal system converts the NRZ signal of the output of an identifying circuit 3 to an RZ signal with a clock CK of the output of a timing circuit 4 and an LD light emitting element 7 is driven by an LD driving circuit 6. When a loop-back is executed from an ascending regenerative repeater to a descending regenerative repeater, the RZ signal converted by an AND gate 5 is connected through a loopback gate 8 opened and closed with a loopback control signal LBS1 from an SV control circuit 17 to the input of an AND gate 13 of the descending regenerative repeater. The loopback from the descending regenerative repeater to the ascending regenerative repeater also connects the output of the AND gate 13, which is a main signal system NRZ/RZ converting gate, through a loopback gate 19 opened and closed by a loopback control signal LBS2 to the input of the AND gate 5 of the ascending regenerative repeater. |
