| 摘要 |
PURPOSE:To detect precise time by detecting a zero cross or a slope code change point of a sine wave electric signal of a time announcing sound and making a pulse signal by the timing to count it. CONSTITUTION:A pulse signal 3 is generated by a zero cross of a sine wave 1 of a time announcing sound. Or another pulse signal 4 is generated by a change point of a slope code of the sine wave 1 of the time announcing sound. In the case of the sine wave 2 of the time announcing sound in which the difference from the wave 1 in the phase is 180 deg., the signal 3 of the zero cross and the signal 4 of the slope code change point are also generated. On the other hand, since the cycle of the time announcing sound of 880Hz is 1.13636ms, the cycle of the signal 3 and the signal 4 of the slope code change is 0.568181ms. Since these pulse signals can be processed to distinguish the time announcing sound and the other sound signals by a digital filter and the like, deterioration of precision caused by outside factors does not occur. |
