To always keep a time error to a minimum by periodically detecting only a time-casting pulse signals frequency from a broadcasting electric wave and performing time correction at a detected timing.
A counting unit 5 counts a pulse generated at a crystal oscillating unit 4, counts a second digit up to 59, counts a minute digit at 60-th second, counts 60 minutes, and calculates one hour. A synchronizing unit 9, by synchronizing a broadcasting electric wave manually set at a synchronous frequency setting unit 12, received the set wave and modulates it by a detecting unit 10. A signal detecting unit 11 compares a signal containing a clock pulse from a wave detecting unit 10 with a clock pulse signal setting preset at a reference signal setting unit 13 and detects it as a clock pulse when it is matched. An integration unit 6 performs correction at a correct time based on the detected clock pulse, and a display unit 8 displays a corrected time. Thereby, a fine error (2 to 3 seconds per month) that a crystal oscillating clock has is periodically corrected.
TAKAHASHI SHINICHI
FUJINO NOBUHIRO
AOKI SATORU
NARITA TAKAMITSU
