But many experts thought it would take a decade or so until technology was advanced enough to squeeze a digital HDTV signal into a single channel.

That is because the vast amount of data in an HDTV signal requires at least 10 megabytes of computer memory.

Zenith's HDTV signal, it says, uses less than 0.2 percent of the power needed for regular transmissions.

Some HDTV signals display certain types of broadcasts better than others.

HDTV signals can also be progressive, meaning that the each frame of the moving image is a whole picture rather than half of one.

Each station would be required to begin transmitting HDTV signals within five years of the adoption of the standard.

Television sets capable of receiving HDTV signals could be available as early as 1995.

For buyers of the first sets, the only sure way to receive an HDTV signal is with an over-the-air television antenna.

Indeed, because the HDTV signals required more space in the spectrum, broadcasters feared that some stations might be crowded off the air altogether.

It includes equipment for the production, transmission and reception of HDTV signals.