| 摘要 |
PURPOSE:To generate a correct time signal by conducting initial synchronization periodically by a time signal contained in TV broadcasting wave signals and by executing synchronization monitoring and synchronization control at an interval of a short time by a picture signal. CONSTITUTION:A TV wave from a broadcasting station is led to an amplifier 102 through an antenna 101, amplified therein to be at a required level and inputted to a band-pass filter 103 and a sync signal separator 111. When a correct-time sound is contained in signals inputted to the band-pass filter 103, it is extracted and inputted to the next pulse generator 104, and a pulse generated in the generator 104 on receiving said signal is led to a frequency divider 107 of a clock device 105. Meanwhile, the frequency of a clock pulse other than the one of a correct time is always corrected by a picture sync signal contained in TV broadcasting waves extracted from outputs of the amplifier 102 by the sync signal separator 111. According to this constitution, there occurs no disorder in a time signal when forced synchronization with exact correct-time casting is executed once a day. |
