In Reply #1, Zach said
Converting to digital with the proprietary IBOC system would just be a big fat cash gift to iBiquity, and frankly they don't deserve the handout. It COULD work, but the painful transition period would hurt radio for a long time. (I believe that IBOC stations running 'full digital' with no analog signal would be a lot more robust, but that's just a hunch.)
And in Reply #4, DaveBayArea responded
The other thing is that the IBOC system today is set to run on FM frequencies - 88 to 108 MHz. DAB operates in the high VHF band (174-240 MHz) or the L-band (1452-1492 MHz). The higher frequencies are much more suited to digital transmission due to less impulse noise. Those television broadcasters who were saddled with a low-VHF channel during the DTV transition found out about that problem in a hurry.
I honestly question whether it would work to the satisfaction of most radio listeners.
Actually, Dave, based on the experience of OTA digital TV, there’s really no question. It wouldn’t work.
Let’s look at the Philadelphia market. Only two of the four stations originally on VHF elected to move their digital signals to their original VHF channels when the analog signals were turned off. There were so many complaints about reception of WPVI on channel 6 (82-88) that, within a couple of weeks, the FCC authorized the station to quadruple
While WHYY’s experience on channel 12 (204-210) has been better, that station occasionally has problems not seen in the UHF band. Even with high band VHF, I can lose audio and see freeze-framing for a second or two after switching on (or off) a table lamp next to the antenna wire. (Of course, that may be because I’m still using 300 Ω twin-lead, not 75 Ω coax.)
Remember, OFDM is no more robust than 8VSB. So if an OTA DTV signal in the VHF high band is that vulnerable to impulse noise, how can you expect a digital radio signal in the lower half of the VHF spectrum to provide dependable reception in cars, or on small radios with dangling wire antennas in homes and offices?