| 摘要 |
PURPOSE:To obtain a circuit for detecting a time signal composed of three preceding sounds and one correct time sound in which the correct time sound can be extracted correctly with no error through a simple and cheap circuitry. CONSTITUTION:Preceding sounds in a time signal are extracted through a filter 1 and the duration thereof is measured through a preceding sound detecting circuit 9 thus detecting the preceding sound. A GATE B signal is generated based on a signal obtained upon elapse of a predetermined time after counting of a predetermined number of preceding sounds through a preceding sound counter 10. On the other hand, a GATE A generating circuit 12 generates a GATE A signal upon receiving the preceding sounds at a predetermined interval. Upon receiving a correct time sound, an AND circuit 44 outputs a correction signal. A correct time sound detecting circuit 14 extracts a correct time sound based on a current correction signal and an HOUR GATE from a time counter 15 which has detected a time sound preceding time or before. |
