Justin T. Fanning
Justin at futurecorp.co.uk
Mon Dec 24 10:57:28 EST 2001
Under the current Act, packet or any other form of data transmission
that does not fall under "Telemetry and Telecommand" (The ACA's
examples are monitoring water levels in dams, controlling equipment
such as irrigation pumps, opening and closing gates etc.) is not
permitted under the UHF CB class licence.
What you may be interested in looking into though is the Low Power
Radio Association (http://www.lpra.org/), they have all sorts of
data modules. Australia has wide bandwidth licence free spectrum in
the 900 Mhz, 2.4 Ghz, 5.7 Ghz & 24 Ghz bands. Narrow bandwidth is
available in the 6.7 Mhz, 13 Mhz, 26 Mhz, 29 Mhz, 36 Mhz, 40 Mhz
& 46Mhz bands (and many MANY more!) You can find complete details on
the ACA's web site. Do some searched for "low power", "licence free"
I was looking into the 40 Mhz allocation (40.66 MHz - 40.70 MHz) a few
years back. There is about 40 khz available, with an output power of
1W. Its pretty dirty spectrum, your fighting it out with baby
monitors etc, but 1W is a lot of output power if properly used.
Gary Nicholls wrote:
> I can see where the 27 Mhz band would be limiting, although I think as part
> of a community communications system it might be useful for text messaging,
> but what about UHF between 470 and 800 mhz? My UHF detector (portable B/W
> t/v) has maybe 2 channels with a carrier, and the occasional tow truck or
> taxi conversation. Isnt there 6Mhz per channel here, with guardband, and
> dozens of channels? Of course there are legal problems (Im in Canada) but if
> these channels are not being used, I think the public should have access to
> them for community purposes.
> >> Given that AM-CB modulators are dirt-cheap to make, I'm thinking a
> >> home-brew low-power 27MHz modem (with as much brains as an IrDA port)
> >> could be an alternative..
> >There are legal considerations, but putting those aside, speed will be
> >lacking because of the typical narrow bandwidth available on a CB radio,
> >300-1200 bps is typical on HF radio via amateur radio. The other problem
> >is the communication is simplex, unless you have a receiver & transmitter
> >running together at both ends with enough separation so they don't
> >interfere with each other.
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