There appear to be a number of stations using this low data rate signal. 850
KOA +/- 16Hz; 1110 KFAB +/- 16Hz; 700 +/- 16 Hz. And some with either a +
offset of +14 to +20 and some with a + offset and a different - offset -20
to -14. Of course those might just be other stations off-frequency, hard to
tell for sure. Info on the specs of this presumed low-data rate signal would
be nice to read about.
Steve
----- Original Message -----
From: "Barry McLarnon" <b...@bdmcomm.ca>
To: "Mailing list for the International Radio Club of America"
<irca@hard-core-dx.com>
Sent: Wednesday, December 22, 2010 5:23 PM
Subject: Re: [IRCA] Fw: [Lowfer] Growling audio on MWBC signals
On Wednesday 22 December 2010 17:51:27 sc...@fybush.com wrote:
> Something I hadn't known about Clear Channel stations, apparently they
> all have this....
> Steve
I don't think they all do yet...or even many of them. I've yet to see any
gear installed for this at any of the stations I've visited.
I wonder if the source of the "growling"has been mis-identified. 16 Hz,
after all, is pretty much below the lower limit of the human audio
perception
range. Since the station in question (KSL) also runs IBOC, consider the
possibility that this is actually the source of the noise. The AM IBOC
signal includes a pair of low frequency reference subcarriers (at +/- 182
Hz
from the carrier) that are transmitted with a quadrature phase
relationship
so that they don't produce any audible output (in theory, at least) from
an
AM detector. If you tune to the signal in SSB mode, however, this
relationship becomes unbalanced, and you can hear a low-frequency rumbling
sound along with the program audio. Maybe this is the source of the
"growling"?
Barry
--
Barry McLarnon VE3JF Ottawa, ON
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