Patent ID: 7995915

Claim:
Portable apparatus for measuring parameters of at least one of optical signals propagating concurrently in opposite directions in an optical transmission path between two elements, at least one of the elements being operative to transmit a first optical signal (S 1 ) only if it continues to receive a second optical signal (S 2 ) from the other of said elements, the apparatus comprising first and second connector means for connecting the apparatus into the optical transmission path in series therewith, and means connected between the first and second connector means for transferring at least said second optical signal (S 2 ) towards said at least one of the elements, measuring said parameters of said first optical signal (S 1 ) and outputting the measurement, wherein the means connected between the first and second connector means comprises optical-electrical-optical regeneration means ( 58 ″, 70 ) for producing from a said second optical signal (S 2 ) received from the second element a regenerated second optical signal and supplying the regenerated second optical signal to the said one of the elements as the second optical signal (S 2 ).