HD radio question

[-TJ-]

<font color=3333ff>Is HD and sub-channels for both AM and FM? Or is it only a FM thing?

And if it's a AM thing too, how will this affect the overnight skip of the AM signals across the country? The signals don't travel as much as the analog right?

That'd be sad cuz I remember traveling from Miami to home and listening to WBBM AM in Atlanta and that was fun! WMAQ 670 (was my first choice) faded when I got to FL since a Spanish station came in.
</font>

 

[Mediafrog]

> Is HD and sub-channels for both AM and FM? Or is it only a
> FM thing?

HD can be either on the AM or FM bands, but the AM version is inferior...more like a decent internet stream--okay for talk, but digital artifacts show up with music.

Multicasting is on FM only. Insufficient bandwidth on the AM IBOC technology.

 

[tpt]

IBOC on AM will cause both first adjacent and second adjacent interference, There is a "carrier" for lack of a better term) at 19 khz. that sounds like a 1,000 demonic cicadas when you are listeni9ng to a second adjacent station.

Because many tight directional patterns also have limited bandwidth, the IBOC signal may interfere with adjacent channel staitons because the adjacent channel IBOC signal is not properly nulled towards that adjacent channel station. Even if the IBOC station is properly nulled on the main channel.

And this is daytime.

Mighttime AM IBOC will be a disaster. I doubt that the FCC will authorize it except on a limited, experimental basis. I suspect that the Canadians will protest if it is authroized. And some medium size operator (who hasn't bought into this nonsense) will sue.

FM doesn't seem to be a problem, but I have not heard it in tight allocation situations. The secondary channel is a nice toy, but without receivers, no more than that.