| 摘要 |
<p>To be able to monitor all operational regenerative repeaters ZR1 to ZRn in the outgoing and incoming direction in the case of an interruption or when such a transmission link is being set up, the telemetry signal in the regenerative repeaters ZR2 and ZRn located immediately in front of and behind the break F is looped back via telemetry signal switches TUg and TUk in the opposite direction to the line terminal devices LE1 and LE2, respectively, feeding in this telemetry signal. The telemetry signal switches TUg and TUk are controlled by system dependability circuits which are preferably constructed as laser shutdown units LAg, LAk in the case of an optical transmission. <IMAGE></p> |
