Patent ID: 6842586

Claim:
A method of using optical time-domain reflectometry (OTDR) with a WDM transmission system that includes a plurality of terminals interconnected by at least two pairs of unidirectional optical transmission paths each of which has at least one repeater therein, said method comprising the steps of: transmitting an optical probe signal from a first OTDR unit associated with a first terminal into the repeater over a first optical path in a first of the at least two pairs of unidirectional optical transmission paths; receiving by the first OTDR unit a first returned OTDR signal over a second optical path in the first optical path pair, said first OTDR signal containing status information concerning the first optical path in the first optical path pair; coupling the optical probe signal from the first optical path in the first optical path pair to a second optical path in the second optical path pair, said first optical path in the first optical path pair supporting optical signals traveling in a direction opposite to optical signals supported by the second optical path in the second optical path pair; receiving over a first optical path in the second optical path pair a second returned OTDR signal in which status information concerning the second optical path in the second optical path pair is embodied, said second returned OTDR signal traversing a repeater located in the second optical path pair; and coupling the second returned OTDR signal from the first optical path in the second optical path pair to the second optical path in the first optical path pair so that the second OTDR signal is returned to the first OTDR unit, said first optical path in the second optical path pair supporting optical signals traveling in a direction opposite to optical signals supported by the second optical path in the first optical path pair.