HDTV has five times the information as standard TV and creates a deeper sense of realism. Japan already broadcasts a daily HDTV station which has even covered some of the big events like Wimbledon and the Olympics, as well as news and general entertainment. HDTV is slowly expanding. Other stations across the country were right behind. HDTV transmits on its own completely digital signal.
Standard television transmits a lower quality analog signal.
Therefore stations have to broadcast HDTV signals simultaneously on a different station than their traditional programming broadcasts. Because this is a very costly change for the broadcasting stations and because until enough people have converted to digital sets they would have to operate both an analog and a digital broadcast for awhile, progress has been slow. This basically means that the current television sets and antennas will not work beyond that transition date and will have to be either replaced with a new digital set, or use some other form of receiving the digital signal like a digital satellite dish or an adaptor of some sort. Combined with the system's line doubler, the resolution output was phenomenal. Clean, crisp images and enveloping sound were present, although the selection of program material was pretty slim.