#1.. HD Radio uses side-band frequencies. These are part of current station licenses. Back in the '70's, we used 'em on FM when quadrophonic (4-channel) was all the rage.

#2.. This would/does, still require a standard broadcast setup. Over 30,000 applications for new stations are received by the F.C.C. yearly. There isn't any bandwidth left.

#3.. Even if you could secure an open frequency in your area, you're still looking at $20,000 & up for engineering and attorney fees. That's even before you get a yes or "maybe" from the F.C.C.

Been there. Done that. Got a "no".

See, the other problem is.. Even if the F.C.C. gives a "maybe" or even a "yes" there's a frequency open in your location, EVERY radio station in the U.S., Mexico & Canada knows about it. If even ONE of them says "that frequency would cause me problems between the hours of 2 & 3 A.M." you got a fight on your hands. (Translate that as.. $$$$$$$$)

BTW.. Low-Power TV stations are also gone now.

Pete