Tom Wells said:Exactly! A telephone IS a balanced distibution of frequencies. Three hundred to three thousand hz, period.
Not a desirable frequency response, but balanced and more intelligible than AM when brickwalled at the station and center tuned for HD.
I agree that music needs bass, and simplify the "speaker size" issue in order to say there should be less bass as there is less treble.
I also know that there is a great difference in high-end response limits from station to station, and they're not complying to the same standard.
If you're hearing "splat" from side-tuning on AM, you have tuned past the carrier and are receiving sideband only.
If you then open up your bandwidth, you will find the distortion is gone.
I, too deplore engineers with no ears.
But it is worse to hear something "wrong" and pretend everything is OK to satisfy "the man".
I will not pretend everything is OK with the analog left over after HD is added.
I also keep hearing reference to "legality".
With all due respect, I think the precedent has been set by ibiquity.
Seems it's OK to put sidebands out to 20khz continuously.
So of course it's no problem to have modulation out there 2 to 3 per cent of the time....
It's only your receiver that makes you think that an HD station is transmitting out to 20 Khz. Take a look at the signal on a spectrum analyzer. While you think you are hearing the IBOC signal across the band what you are actually experiencing is poor skirt selectivity. In analogue words the entire channel is being modulated at 100% as opposed to analog peaks which while they cause interference to first adjacents because it isn't a constant interference, people/DXers can usually get an ID through the noise. Because of the 100% IBOC audio to the channel edges, analog radios can not deal with the perfectly legal IBOC next door neighbor because they really weren't designed to do so. Nevertheless, just because a receiver lacks for selectivity doesn't mean that stations are operating illegally. I posted a demo of a Non HD station on a second adjacent to a 50KW local IBOC and there was no IBOC interference and I am in a null of that station which is over 70 miles from my location.