[BC] Re: SUPER MODULATION & AM STANDARDS

[DANA PUOPOLO]

Actually IBOC is worse, Dave..

First off, unlike analog audio, it's always there. It's power distribution
curve looks like  a square wave - it stays out at 100% all the way to the edge
of the channel. Analog has its maximum amplitude at carrier, falling off
gradually toward the channel edges.

Do remember, in the days of supermodulation, most AM stations had (some) audio
out to at least 15 kHz - no NRSC filters!

Second, when detected by an analog detector, it has a "buzz jamming" sound,
which is psychoacoustically gnawing to human ears. Our ears tend to hear sound
as a whole rather then it's parts. This is how masking (perceptual coding)
works. The buzz saw sound draws attention to itself because of its dominance.


-D



------ Original Message ------
Received: Sat, 14 May 2005 03:43:18 PM PDT
From: "Dave Dunsmoor" <mrfixit at min.midco.net>
To: "Broadcast Radio Mailing List" <broadcast at radiolists.net>
Subject: Re: [BC] Re: SUPER MODULATION & AM STANDARDS



> The 125% limit was put into effect because of splatter.  Stations that
> supermodulated (especially ones near the top of the dial) used to splatter
> like crazy, wiping out most stations within 20 or 30 kHz away.

So, how does this differ from IBOC, in effect? IBOC is ok, but "splatter" is
not?
And, I'm not directing this question specifically to you, Dana, but to the
engineering community at large.
I fail to see the benefit, even after a couple years' worth of
discussion/debate.

Dave


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