| 摘要 |
<p>PURPOSE:To perform failure retrieval simply by the synthesized signal f2+ or -f1 by transmitting two monitor signals f1, f2, from the terminal stations, synthesizing in the relay unit. CONSTITUTION:In the relay transmission system of one line bidirectional method, the line monitor signal f1 is transmitted from one terminal station (low group transmission terminal station etc.) and the monitor signal f2 is from another terminal station (high group transmission terminal station etc.). The band pass filters 201, 202 the signals f1, f2 and produce the failure retrieval and monitor signal of f2+ or -f1 in the frequency converter 203. The signal is coupled at the output point of the low and high group amplifiers 105, 106, and f2-f1 is given to the low group band and f2+f1 is to the high group band. Accordingly, the number of relay units and failure can be monitored at each reception terminal station by only detecting the level of the failure retrieval and monitor signal. Further, the frequency of the failure retrieval and monitor signal is single enough to monitor the entire relay units, the occupied area can be less, and the line can effectively be used.</p> |
