| 摘要 |
<p>An analogue telemetry system/method provides fault location in an optical transmission system including optical fibre amplifiers. Each amplifier includes an optical fibre amplifier with an AGC loop therearound, a respective optical pump source being included in the AGC loop. In the AGC loop the spontaneous emissions from the amplifier fibre is detected and employed to drive the pump source appropriately to maintain the amplifier output at a predetermined level. A supervisory tone is applied at the transmission end of the system. At each amplifier the presence of the supervisory tone or a distress tone from a previous amplifier is looked for. If either tone is detected the signal is amplified and transmitted to the next amplifier. If neither tone is detected a respective amplifier distress tone is applied to the respective optical pump source. At the receiver end of the system the supervisory tone is sought or, in its absence, a distress tone or no tone at all from this information the position of a system fault determined.</p> |
