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Re: Solving the need for ISA or USB slots and Serial Ports

> If you are going to use Ethernet, you probably want to think about
> what protocols you want to run within the Ethernet frames.  With
> enough effort, you could encapsulate your rotor control protocol 
> directly
> within Ethernet frames.  However, an easier solution is to run
> IP over the Ethernet frames, and then run your rotor control protocol
> on top of IP (e.g., using TCP or UDP).  The advantages of IP include:
> o	Many devices already support an IP stack, so your development
> 	would be limited to writing the rotor control application,
> 	rather than mucking around trying to implement network
> 	protocols directly on top of Ethernet.
> o	IP potentially eliminates any distance limitations.  You
> 	could control your rotor from work, or from around the world.
> 	Of course, if you don't secure your Internet-attached
> 	rotor, then potentially anyone else on the Internet could
> 	control it as well.

My vote goes with TCP/UDP over IP, hands down.  There are way too many 
out of band protocols running around on LAN's as it is, and not all 
switches or routers deal with those gracefully.  I have painful 
experience with that sort of thing.  TCP has the advantage of being the 
primary protocol the routers were designed to deal with in the first 
place, so even if you have a router/firewall at your house, if you 
*want* to open up control of your rotator to the whole world, you can 
bust open the port via IPM or whatever and allow connections to the 
rotator.  (Visions of an az/el mount going berserk when the teenage 
h4><0r across the street finds its address and figures out enough of 
the protocol to be dangerous .. ;-)  It is also very well suited to 
being routed via VPN, a more sensible approach for remote control 
operations from work.

Mind you .. if you can figure out a way to tie EchoLink into it, and 
maybe some remote console control for your radio, you could carry on 
entire QSO's via VoIP.  *If* your employer will put up with that sort 
of thing .. mine won't.

> My favorite embedded Ethernet single board computer (SBC)
> is the Dallas Semiconductor TINI board.  This SBC has a
> reasonably good Java implementation.

Don't personally know much about this, but found the page at 
http://www.ibutton.com/TINI/ and will read over it when I have time .. 
definitely looks useful.  I suspect that with the right front end and 
integration to other hardware at the nodes, this could be a very 
powerful little device in terms of doing stuff remotely.  Not just 
rotators, either -- remote antenna tuners, coax switches, switching 
phasing lines in and out, reversing sense of a circular Yagi as needed, 
all sorts of stuff.  Much easier than having a big rack of switches and 
relays in your shack, and what's even more fun, you could even put in 
fiber to Cat 5 transceivers for really large installations to kill 
ground gradients from lightning hits.  All sorts of possibilities there 
"Many that live deserve death. And some that die deserve
life. Can you give it to them? Then do not be too eager to deal out
death in judgement. Even the very wise cannot see all ends." -- Gandalf

Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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