There's no doubt in my mind that IBOC on AM is, at best, a con. If it works at all,
it will be only in the metro coverage, as the digital sidebands, down 39db from
carrier if I read the document linked below correctly.

FM won't be much better. If your digital stream is in the noise, it won't be
available to the receiver.

It's fairly apparent that most decisionmakers in radio these days don't know what to
listen for (otherwise radio would sound better), so when they hear "digital" or
"high-definition" (a misnomer if there ever was one) they're all ears and wallets.

Barnum was right. A shame, really. The Canadians have a better way to do it, and it
ain't IBOC.

And for what it's worth, so was Nyquist. You can't get 15kHz through a channel only
designed to properly sample 5kHz.

For your reading pleasure.....
AM IBOC Standards: http://hraunfoss.fcc.gov/edocs_publi...C-02-286A3.pdf
FM IBOC Standards: http://hraunfoss.fcc.gov/edocs_publi...C-02-286A2.pdf


"WBRW" wrote in message ...
Even disregarding the subtleties (of which there are many), these two
factors alone make HD AM dramatically superior to analog AM stereo.

If IBOC were running pure compressed digital audio, that would be
true!! However, IBOC on AM is only 36 kbps, and only maintains
accurate frequency response up to _5 kHz_ -- all audio above that
point is "spectrally replicated", i.e. "faked" based on harmonics of
lower frequencies. To my ears, it sounds like the treble has been run
through a cheese grater!

Analog AM may have a more limited high frequency response, but at
least it is ACCURATE treble response -- not screechy, gritty, heavily
artifacted treble that is about as pleasing to the ears as fingernails
scratching on a chalkboard.

A new comparison between analog AM Stereo and digital IBOC/"HD Radio"
AM can be found on this site:

http://www.geocities.com/kevtronics

Download the audio samples of both, and compare!

p.s. One thing I can say, however, is that your Optimod 9100-B2 is the
best-sounding analog AM audio processor that has ever been built --
and, of course, it really shines with AM Stereo. Stations which just
want to be LOUD use the 9200... but stations which want to be both
loud AND good-sounding almost universally use the 9100.