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[aprssig] Parallel UHF APRS level-4 node system.

J. Lance Cotton josecanuc at gmail.com
Tue Dec 28 19:52:29 UTC 2004


On Tue, 28 Dec 2004 13:36:11 -0600, John Denison <kd5you at houston.rr.com> wrote:
> Icom has a system called the D-STAR which operates at 128k on 1.2 and 10
> GHz. I've just started getting into packet, but from a newbie point of
> view, I wonder why 1200 baud is still being used. We left 1200 baud
> behind years ago in computer modems, so why is ham radio still lingering
> behind? If high speed data occurs on wireless routers at 2.4 GHz, then
> there is no reason why we can't meet or exceed that standard with our
> own implementations.

My thoughts on why hams are still at 1200bps (and less frequently
9600bps) are that it is a result of one of many factors, but in
particular: Bandwidth limitations.

That 128 kbps DSTAR system has a signal bandwidth of 130 kHz (source:
http://www.icomamerica.com/amateur/dstar/default.asp ) U.S. Amateurs
are, I think, not allowed to use bandwidths that high except at 70cm
and shorter wavelengths (but PLEASE correct me if I'm wrong)

Of course equipment cost at <70cm wavelengths is another large factor,
but it's been examined ad naseum here...

Spread spectrum is great, and I hope amateurs start coming up with
easy to implement SS modes that are legal to use...
-- 
J. Lance Cotton, KJ5O
joe at lightnigflash.net
http://kj5o.lightningflash.net
Three Step Plan: 1. Take over the world. 2. Get a lot of cookies. 3.
Eat the cookies.




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