| 摘要 |
PURPOSE:To inspect telephone lines collectively in a prescribed place and to inform the disconnection of a line to a monitor station, by discriminating the disconnection in a specific area and informing the disconnection together with the telephone number. CONSTITUTION:Trigger pulses are sent from a pulse generating circuit 41 to an address selecting circuit 42. The circuit 42 stores addresses corresponding to subscriber's telephone numbers. A relay driving circuit 43 drives a relay Ai corresponding to the selected address. A discriminating means 5 sends a low frequency signal to the telephone line. Only when a retrieval signal is received from a delay circuit 44, a discrimination circuit 53 is started. When unbalanced voltage is normal as compared to reference voltage, the discrimination circuit 53 advances the disconnection detection to the succeeding line, and only when disconnection is detected, sends a starting signal and a pulse stopping signal. The stopping signal informs the disconnection to a disconnection alarming center and then makes the pulse generating circuit 41 generate pulses again. Simultaneously, the starting signal is send to start a failure information device 7. A data generating circuit 72 starts a centeral telephone number storing circuit 73 to make an automatic dialing circuit 75 dial to the alarm center 2 automatically. |
