"Frank Dresser" wrote in message
...
"Doug Smith W9WI" wrote in message
...
It's commonly not understood by non-engineers that a radio station
(broadcasting or otherwise) causes interference over a much wider area
than it provides service. This is especially true on AM where multiple
signals on the same frequency mix together.
The open frequencies I mentioned aren't silent, but are a mish-mash of low
power signals. They aren't useful in this area.
Then they're not "open". And adding another signal, even a low power one, in this
space would then interfere with the otherwise serviceable coverage closer in to these
stations.
The new Chicago X-band station moved from downstate - Johnson City IIRC.
A station on that frequency in Chicago would not have been allowed if
WRLL had been operating downstate.
I live within 15 miles of WRLL, and it's almost unlistenable at night after
they drop power to 1 kW. Skywave comes in from all over. A much larger
number of daytimers could be worked out, however.
That doesn't make the area unserved by WRLL's nighttime pattern "open". A facility
allowed to fill in this "unserved" area would interfere with the stations whose
skywaves come in from all over. And the FCC no longer licenses daytimers, and all
attempts to apply for one will be rejected on this criteria. As it is, the FCC is
looking for daytimers below 1600 (and encourages, through policies in place) to move
to the X-band, in order to clear out the congestion and permit more regional service
by the full-time stations on those frequencies.
That's the point. The allowable amount of interference isn't really a
technical consideration. At one extreme, we could have a very small number
of true clear channel stations. Or we could have super saturated radio
markets in which the only clear reception would be within the shadow of the
station's antenna. Allowable interference is a political consideration, not
a technical one.
Actually, no. The interference standards provide for usable coverages to the limits
of receivers (very few radios will provide a listenable output at 500uV, the current
protection limit for nighttime service, which affords a 26dB signal to noise ratio,
give-or-take). But protecting out to that limit means that for every 20dB increase
in signal strength for the desired station (by moving closer to the transmitter) also
means at least a 20dB boost in the signal to noise ratio...thus, the rural-grade
5mV/m contour would be a listenable signal. Allowing increased interference (by
raising the protected contour to, say, 2mV/m) means that a listenable signal would be
obtained at the 20mVm contour....which is a metro-grade signal-strength. So, in the
interest of expanding coverage, you'd actually be reducing it. For both the new, as
well as the existing, stations.
All the details about how this is done can be found at
http://kauko.hallikainen.org/FCC/FccRules/2003/73/182/ and
http://kauko.hallikainen.org/FCC/FccRules/2003/73/37/
IMHO the FCC has grounds to regulate both services on content if they
chose to do so. IMHO they need to either do so, or lift content
regulations on OTA.
Maybe so....but, for the former proposal, would you want a situation where the FCC
can delve into the private affairs of these operations? You know, the next step
would be censoring telephone conversations, as the analogy holds. Subscription
services, and other non-broadcasting licensees, are not public entities. Better that
if the FCC feels obliged to limit what can be said on OTA, they feel that it's the
only area where such pervue exists. While I'm not so keen to remove those
restrictions on OTA, the Canadians and other democracies have no such limits
(although there's some discretion in how often the ability to say anything is
exploited) and they haven't come to the end of the world.
--
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If there's nothing that offends you in your community, then you know you're not
living in a free society.
Kim Campbell - ex-Prime Minister of Canada - 2004
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