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Re: Cable Modems on HAM bands?



One issue that would have to be dealt with, if one was to use DOCSIS modems
for the purposes described (and I do think this is an idea with merit), is
that DOCSIS modems are designed to be completely controlled by the "head
end" for security, rate-control and frequency assignment purposes.  These
aren't insurmountable issues, but they do increase the complexity a bit.

73,

Rick
KG6IAL
www.teksharp.com

----- Original Message ----- 
From: "Adi Linden" <adil@adis.on.ca>
To: "Bob Bruninga" <bruninga@usna.edu>
Cc: <amsat-bb@AMSAT.Org>; "TAPR APRS SIG" <aprssig@lists.tapr.org>
Sent: Friday, May 16, 2003 7:55 AM
Subject: Re: [amsat-bb] 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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