| 摘要 |
<p>PURPOSE:To attain accurate discrimination by using a gate pulse generated from a detection pulse of one preceding frame so as to gate a detection pulse of a frame synchronization signal thereby avoiding noise from being discriminated in error as a detection pulse. CONSTITUTION:A frame pulse with a shorter period than one frame period is inputted to one gate 11 of AND gates 11, 12 except the reception of an HDTV signal and no pulse is inputted to the other gate 12 and its output is at a low level. An up-down counter 13 is counted up by a frame pulse from the AND gate 11 and the AND gate 11 is closed when the count value reaches F, then the count-up is stopped and the state is continued afterward.</p> |
