Single cable optical fibre signaling system

摘要

A single optical fibre cable signaling system is provided between a central station and a remote location wherein a shutter element is movable between first and second positions at the remote location in response to a change in the measured variable. The shutter element and the interior of a housing surrounding the end of the cable have cooperating light reflecting and light absorbing surfaces which are effective in one position in the shutter element to absorb unmodulated light transmitted from a source of the central station over the cable to the remote location and prevent the same from being transmitted back over the cable and are effective in the other position of the shutter element to reflect unmodulated light transmitted to the remote location back over the cable to the central station.