For those who wonder why the big jump to UHF by the formerly analog stations I can explain....
The higher the carrier frequency (Broadcast channel) the more data can be crammed into the signal.. I do digital radio (As I said before ALL television is a form of radio) on many frequencies.. The SPEED of transmission .. Depends on the frequency to some extend (The maximum speed) and the mode.. 31 CPS.. 45.45 1400.. All frequency dependent.. HF is slow, VHF faster and UHF faster still.
So where as, for example, Detroit Channel 2 (56MHZ) used to be one analog signal.. Today they broadcast on Channel 7 (I'd have to look up the frequency) and 2 or 3 (forget which looked up on other comptuer...2) as you go up in frequency to UHF many have snuck in a 4th sub channel and at least one a 5th.. (That's about the limit before quality drops) the higher the frequency you transmit on (The carrier channel or broadcast channel) the more data you can stuff.