| 摘要 |
PURPOSE: To simplify the circuit configuration by fetching the signal component of a specific frequency included in a time signal by a BPF, detecting that it is continued for a predetermined time or more, and time correcting only one degree in the time correcting range before or after the time signal when the time is corrected. CONSTITUTION: When one wave of a frequency 880Hz included in a time signal is received by 880Hz BPF, its output is waveform shaped by a waveform shaper 13. A square wave of 880Hz is output to a CPU 15. The CPU 15 operates a frequency discriminating counter contained therein, and monitors whether the square wave is continued for 2 seconds or more or not. The CPU 15 then checks whether the present time is between 55 minutes to 59 minutes or not, and when the present time is therebetween, the correction for adding '+1' to the present time is conducted. Then, the second correction for setting the second of the present time to '02' and the minute correction for setting the minute of the present time to '00' are conducted. Thereafter, a two second counter for counting two seconds is cleared, and a frequency discriminating counter is cleared, thereby finishing the time correction. |
