vertical-hold control
Quick Summary
The vertical-hold control on a television is a manual adjustment that ensures the picture on the screen remains stable. It works by synchronizing the vertical deflection generator with the incoming vertical synchronizing impulses from the broadcast signal. This process is crucial for maintaining a steady image and preventing the picture from rolling or becoming distorted.1
The vertical blanking interval, a brief pause between the end of one image and the beginning of the next, was originally necessary for the electron gun in cathode-ray tube televisions to return to its starting position. This interval is now also used to carry additional data alongside the main video signal.2
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