AP - Digital over-the-air TV transmissions require a lot of broadcast spectrum. But when TV stations aren't transmitting digital signals - the spectrum is wide enough for each station to transmit four different TV signals at once. And that allows the viewer to choose the one program they want to watch.
CBS experimented with the technology during the NCAA basketball tournament. One channel offered the primary game, but the other three channels offered different regional games.
This wide broadcast spectrum also makes it easier for viewers to interact with their TV sets. Take an NFL game, for instance. The viewer could split the screen and have the game on one half while calling up statistics of a player on the other.
John Orlando with the National Association of Broadcasters says it may be a while before TV broadcasters regularly offer interactive programming. He says there's one simple reason why: the number one priority right now is get their digital infrastructure in place.