| 摘要 |
<p>PURPOSE:To detect a failure generated section in a short time, by providing an oscillator which oscillates the same frequency to a plurality of relay devices given with address and transmitting the output of the oscillator to a transmission line only when a control signal in coincidence with the address is detected. CONSTITUTION:When a control signal CTS is applied from a terminal station A, a control signal detector DET of a relay device REP is operated and an output of an oscillator OSC is transmitted to the terminal station A and the signal is detected at the terminal station A via a filter BPF. The oscillator OSC transmits the output to the transmission line only when it detects the output of the detector DET. The control signal CTS becomes an address instruction signal with a single frequency burst signal outside the transmission frequency band from a terminal station to be monitored to constitute continuous repetitive pattern. The monitor signal detector DET only in the relay device of the corresponding address among relay devices REP1-REPn and transmits the output of the oscillator to the transmission line. The section of signal intermission can be detected by measuring the signal level at the terminal station, by changing the address designation of the relay device one after another.</p> |
