Within any 6 MHz channel, there can be up to four program channels. Except if one channel is HDTV 1080i,then there is only enough bandwidth for two other channels. I suppose if a station is cheap enough not to buy the equipment, they would still use the full 6Mz bandwidth for one channel, which, I agree, is a waste.
The magic of DTV is due to digital compression: if the same pixels are in subsequent frames, they are not transmitted twice. There is also a time- to frequency domain conversion done digitally that allows further compression. A full, uncompressed, HDTV signal would require 290 Mbyte/second, the actual data are 19.38 Mbytes/second on a channel, that is how powerful the compression is. PBS in Buffalo NY is transmitting three channels, the regular WNED feed, plus a HDTV feed which is sometimes the same as the regular analog WNED and sometimes has special programming, and a third children's educational channel. Other Buffalo stations are transmitting combinations of old movies, live sports, and local WX and road condx on their other channels. If you want further information, I highly recommend "Digital television Fundamentals" by Michael Robin and Michel Poulin. I am teaching this at college and found the book very useful in switching from the old analog course to digital. 73, Nigel ve3id --- In Repeater-Builder@yahoogroups.com, "Richard" <[EMAIL PROTECTED]> wrote: > > I can't picture that ever happening; I understand it will allow each station > to broadcast multiple programs, should they choose to. > > Richard > <http://www.n7tgb.net/> www.n7tgb.net > >
