Re: 900 mhz "radio" != "cell-phone" ?
> are there radios available, that can use the 900 mhz range, without
> those radios being considered as 'cell-phones' ? ( and hand-helds
> ... something in the text of that page makes me wonder if it's a
> home-based system )
>
> ( and how do they avoid conflicting with cell-phone traffic in that
> range? is there a special "public" part of it? any URLs would be
> appreciated. )
The Metricom units operate spread spectrum on 162 channels in the
902-928 MHz band. They are allowed to operate under the unlicensed
low-power rules in Part 15. Devices in this class are limited to
1 Watt output and must change channels at least once every 400 ms.
At least some models of the devices are intended to be portable.
Metricom is trying to sell internet connectivity through metropolitan
coverage areas where they've installed their network of pole-top
service units. This service is called Ricochet.
Cell phones operate in different frequency ranges. Thus, they don't
interfere with the Metricom stuff. Of course, the Metricom units
don't suffer much from interference anyway, since they're spread
spectrum devices.
The 902-928 band corresponds exactly to the amateur 33 cm band;
hams are secondary users of this band after various government
services and the ISM devices like the Metricom units. A ham could
probably legally modify the Metricom units to put out more power,
and use higher-gain antennas, as long as the over-the-air protocols
and modulation techniques are public specifications.
Oh, and you presumably already know there are Linux drivers for the
Metricom units.
Dennis Boone
KB8ZQZ
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