The vertical blanking interval (VBI) is a portion of a television signal that can carry information other than video or audio, such as closed-caption text and stock market data. The interval in sending a video signal is required for the time it takes the electron gun in a television monitor's cathode ray tube ( CRT ) to move back up to the top of the tube. VBI data can be inserted by a cable TV provider and transmitted to a special receiver that connects to a computer's RS-232C port .

24 Mar 2011