[BC] Re: SUPER MODULATION & AM STANDARDS

[Dave Dunsmoor]

So now that IBOC is coming on line and is (supposedly) going to rule the
day, what's to keep this +125% limit from going away? Might the reversal of
this rule be a good "rebuttal" for those who cannot see the wisdom of
implementing IBOC, but would still like to broadcast out to the fringes?

Dave Dunsmoor


> On 12 May 2005 at 10:18, Lamar Owen wrote:
>
> > So it's not really an interference issue in the positive modulation
> > direction; it's a sidestepping of coverage limits.  You raise the
sidebands
> > up and you get more distance to effective reception.  And you walk on
your
> > co-channels' sidebands, as well as you first adjacents' carriers.
>
> Back in the days when the FCC Broadcast Bureau was run by Harold Kassens,
I
> think you might have gotten a different opinion regarding the fact that it
> WAS an interference issue. This probably was the reason for the RM that
led
> to the limit of 125%, a truly insignificant amount from an interference
> standpoint in the adjacent channel consideration. Remember that there was
> no NRSC frequency limit in those days and modulation in the 12-15 kHz
range
> was relatively common in most plants. There was a time when adjacent
channel
> interference was taken quite seriously. Alas, there are few today that
recall
> those times and none of them are on the Commission.
>
> Phil Alexander, CSRE
> Broadcast Engineering Services and Technology
> (a Div. of Advanced Parts Corporation)
> Ph. (317) 335-2065   FAX (317) 335-9037
>
>
>
>
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