| 摘要 |
PURPOSE:To enable the outputting of a highly accurate time calibration signal with an accurate judgement of time signal information by detecting leading and tailing edges of a prediction signal and a leading edge of a regular time signal to judge whether a time announcing signal is given or not. CONSTITUTION:Audio signal full-wave rectified is converted 6 into a pulse signal with a threshold voltage set by a variable resistance 5 as reference to remove noises. Then, an edge detection circuit 7 inputs the pulse signal to generate leading edge pulses and tailing edge pulses of a prediction signal and a regular time signal four times and three times respectively from a square wave which is generated by a triggering with a built-in mono-stable multivibrator. Then, an MPU 8 measures time T of the respective seven pulses from outputs of a counter 9 while a time length (t) between the pulses is calculated. When the time length (t) is held within a range of allowable error, time announcing information is determined. Then, errors are determined between the time T of the four leading edge pulses and the regular time to send a calibration signal after a fixed time based on a mean of the errors. |
