This should help broadcasters who are under a Congressional mandate to make HDTV the format for transmitted television by next year.

The algorithm combines digital and analog signals such that older TVs can still receive and display the analog signal without using a converter. And newer TVs will just need a software loop in their receivers to recover digital information from the same signal.

The technology gives broadcasters an alternative to broadcasting their signal on two channels — one for HDTV, one for the older analog sets --until HDTV becomes the norm. Currently, researchers estimate only 30% of the U.S. population is familiar with HDTV and that there are still 120 million analog TV sets in use in the U.S.