| 摘要 |
<p>A method of proving the integrity of optical paths in an optical communication system wherein the same diagnostic optical signal is transmitted along each path from one end, and each path is provided at its other end with means, e.g. a grating pattern, for producing a pattern of time spaced echoes of the diagnostic signal unique to that path. In one particular embodiment the diagnostic signal comprises an amplitude modulated optical signal and the echo producing means produces echoes at time spacing such that the modulation components of the echoes are in-phase at a different frequency for each path.</p> |
