| 摘要 |
PURPOSE:To prevent the output of the tone detecting signal due the error signal and to make easy to the circuit integration, by outputting the detection signal when the incoming of a given tone signal is present for set number within a given time by the digital processing. CONSTITUTION:The timing pulse of leading of the rectangular waves of the output signal from the reception circuit 1 is formed with the wave processing circuit 3, and this timing pulse is counted at the counter circuit 4 according to the clock from the reference clock generating circuit 5, and a given tone signal is detected by controlling the detected gate circuit 6 with the output of the circuit 4. The output side of the detecting gate circuit 6 is provided with the discrimination circuit consisting of the gate circuit 15, timer circuit 16, and counter circuit 17. Further, the AND gate 20 of the circuit 15 is controlled with the timing pulse of a given time width produced from the delay circuit 18 and the monostable multivibrator 21 provided at the circuit 16, the output of the circuit 15 is fed to the counter circuit 17, and the detection signal is outputted when the detection signal of a given number is incoming within a given time width. |
