| 摘要 |
PURPOSE:To eliminate the necessity of a no-ringing call for a telephone circuit network controller which performs an automatic inspection of a meter, etc., by starting a code transmitter only in case a telephone is not hooked off while the polarity is inverted continuously for a certain period. CONSTITUTION:In an automtic detection carried out through a center, a network controller of the terminal side which is connected to telephone circuits 13 and 14 detects the polarity inversion of a circuit through a circuit 15 to give an initial resetting to a time limiting circuit 16 and also to start a time limiting action. If a telephone 6 is not hooked off during the time limiting action, a switch circuit 21 is actuated by the on-hook output of an off-hook detecting circuit 18 and the constant time limiting output of the circuit 16. Then a code transmitter 7 of the next stage is connected to a circuit, and the value of a meter 9 is fed to the transmitter 7 via a sensor 8 to be sent to a center. A control is carried out to start the transmission of code while the telephone is not hooked off for a certain period by means of the output of a 16Hz detecting circuit 22 even in the calling mode for inspection of meter in which a call signal arrives. In such way, the same function is realized. |
