It's a very unpleasant listening experience when the AM station starts flipping in and out of HD mode as you drive around. It's much worse on AM than on FM because the AM audio quality changes so drastically, the constant back-and-forth flipping in-and-out of HD mode is just jarring. For me, it's a major tune-out. And this happens quite a bit since HD range seems really limited on AM, even from 50kW flamethrowers.
Honestly, I don't see what benefit broadcasters get from using HD on AM. It makes the analog signal sound worse, it splatters hash noise across multiple adjacent frequencies, it's a major irritant when reception of the HD signal is marginal, you can't stay locked into it on a nighttime skywave signal, and it doesn't provide any side channels that the broadcaster can monetize. It's even more pointless when the same station is available on an FM HD subchannel which sounds better than AM HD and, at least in NYC, provides more robust reception. WCBS 880 sounds great on 101.1 FM HD2, and that subchannel is easy to keep locked in driving all around the metro area. Same goes for 1010 WINS on 102.7 FM HD3. You just don't need the annoyances that IBOC causes on the AM signals.
I like FM HD, but I wish the industry would face the fact that it's worthless on AM, and just turn it off.
Honestly, I don't see what benefit broadcasters get from using HD on AM. It makes the analog signal sound worse, it splatters hash noise across multiple adjacent frequencies, it's a major irritant when reception of the HD signal is marginal, you can't stay locked into it on a nighttime skywave signal, and it doesn't provide any side channels that the broadcaster can monetize. It's even more pointless when the same station is available on an FM HD subchannel which sounds better than AM HD and, at least in NYC, provides more robust reception. WCBS 880 sounds great on 101.1 FM HD2, and that subchannel is easy to keep locked in driving all around the metro area. Same goes for 1010 WINS on 102.7 FM HD3. You just don't need the annoyances that IBOC causes on the AM signals.
I like FM HD, but I wish the industry would face the fact that it's worthless on AM, and just turn it off.