I'm probably 400+ miles from Salt Lake City, Utah but 1160 KSL is a good
signal here presently (an hour or more after sunset), and on Perseus SDR in
CW mode, 8 Hz bandwidth, zoom, I'm easily seeing +/- 16 Hz sidebands
relative to 1160.000. The strongest carrier signal (1160.000) is assumed to
be KSL, which fits with its IBOC-accurate carrier. In AM mode KSL is what
I'm hearing for the dominant station.
(I'm also seeing a +35 Hz fairly strong signal which I assume is some
non-IBOC station, quite aways off frequency; as well as a -11 Hz weak
signal.)
73,
Steve
NE Oregon
----- Original Message -----
From: "Barry McLarnon" <[email protected]>
To: "Mailing list for the International Radio Club of America"
<[email protected]>
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 [email protected] 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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