| 摘要 |
PURPOSE:To remove noise by a method wherein a counter detecting a time-informing sound is maintained in the reset state within 0.9sec after a preliminary sound for time information is detected. CONSTITUTION:A preliminary sound generated with 440Hz for 0.1sec is converted into forty-four rectangular waves and input to a divided-by-44 counter 6. When this counter 6 delivers a carry signal 7, a noise removing circuit 12 puts the counter 6 in the reset state for 0.9sec thereafter so as to prevent the counter 6 from counting the noise. When the counter 6 delivers the carry signal 7 three times, a carry signal 9 is delivered from a ternary counter 8, and a time is corrected thereby 0.9sec later. |
