| 摘要 |
<p>A picture display device comprising a synchronizing signal separating stage, a field synchronizing separating stage, a line synchronizing signal circuit and a field synchronizing circuit. The device also comprises a noise detector for detecting noise in the incoming video signal and for changing over portions of the device in dependence on the detected noise signal. The noise detector comprises a noise separating stage for amplifying the noise present during the occurrence of a sampling pulse, which pulse is derived from the reference signal produced by the line synchronizing circuit. The noise detector further comprises a counting arrangement for counting the number of times the noise signal amplified by the noise separating stage exceeds a predetermined value and for producing a change-over signal when the number found during the counting operation has reached a predetermined value during a predetermined number of line periods in the field trace period.</p> |
