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Re: Cable Modems on HAM bands?



> Any experts want to fill in the modem details and the bandwidths and
> frequencies?

That's an interesting idea. There is a commercial product that does 
something similar. 

Wavecom has a DOCSIS over wireless product. You need proper headend 
equipment, such as a Cisco ubr7111 cable router. The upstream and 
downstream of the cable router are connected to converters which moves the 
spectrum of the cable router into an unlicensed ISM band. At the customer 
premises there is a similar converter that takes the ISM band signal and 
brings it down to something the cable modem can chew.

On a DOCSIS cable system, the downstream (going from the headend to the 
cable modem) typically uses QPSK (64-QAM or 16-QAM). The downstream uses a 
6 MHz channel width in the 85-to-860 MHz frequency range. Effective bit 
rate is about 27Mbps on the downstream.

The upstream (going from the cable modem to the headend) typically uses 
QPSK (or 16-QAM). The upstream supports the 5-to-42 MHz frequency range 
and a typical channel width of 3.2MHz.

Hope this helps...
Adi
-- 
   Adi Linden  |  va3adi  |  va3adi@adis.ca  |  http://adis.ca
+-----------------------------------------------------------------+
            IRLP Node 2590 in Sioux Lookout, Ontario

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