| 摘要 |
PURPOSE:To enhance the reliability of the control by installing the means, which identifies the effectiveness of the signal transferred from the originating terminal unit, to the remote control device which is connected to the telephone switchboard. CONSTITUTION:The subscriber telephone number is transmitted by telephone TEL to start circuit control part LC in remote control device RCE. Then the oscillation sound of oscillator OSC is transmitted to key signal identifying part KS. Identifying that the oscillation sound is identical to the prescribed tone, part KS transmits the connection signal to gate part GT to secure a connection between telephone TEL and the control part. Thus the control can be given to the working of terminal units TEM1-TEMn. Such identification of the key signal enhances the reliability of the control system. |
