On Saturday (02/09/2002 at 07:07AM -0000), Jeffrey C. Lehman wrote:
> 
> I'm just getting into the wireless stuff but i'd be interested in
> participating also.  I live in Columbia Heights (central and st anthony).
> 
> I also have my amateur radio license (KC0JBP). I was thinking about
> running TCP/IP over AX.25.  Anyone ever tried that?  I have a TNC that

yes...  back in 1988 :-)   I had the first 44. IP address here in the
Twin Cities.  But--  not much got done with it.

> will do 9600 bps, but i assume you can find ones that will transmit
> faster.  IIRC the limit on 2Meters is 19.6 but on 440 it's 56k. If a
> couple of us have ham licenses we could set up a backbone that way. Oh
> well, just thinking out loud.

I think there may be some interesting/slightly useful things to do involving
mobile applications.  Andy Warner can comment on the status of it--  but the
9600bps repeater on the top of Moos Tower makes it alot easier to get reliable
link from lots of places around town on UHF.  There is also (or was) a
gateway from the wired Internet to this 9600bps RF network so you could
originate frames on the wired side, destin for some mobile unit on the RF
side.  I envisioned sending real-time or near real-time traffic data 
to a PDA or laptop in the car...   but I never deployed anything.  I think
there might be a fair trade here-- trading lower speed for the ability
to get link from non-LOS locations and moving platforms.  You could certainly
build unlimited SMS (short text messaging) from a PDA+UHF HT w/ internal
TNC.

I am actually still considering 9600bps satellite uplink/downlink capability
in my vehicle for when I travel out west into places with no cellular
coverage and I can't live without my email :-)

56K is alot more work since this is done with a true RF modem (rather than
plumbing audio into the mic and speaker jacks of a voice radio) and you
then get into transmit/receive converters, potentially preamps and poweramps
and associated T/R switching.  A bunch of messing around with not too much
useful return IMHO (except for the learning and experimenting part of course).
But if you are after highspeed, reliable links, I'd throw the effort behind
802.11 stuff any day.

I hate throwing cold water on people's ideas... and that's certainly not my
intention.  It's just that some of us old timers have been down this path
around this town before and not gotten the expected return.  I would encourage
you to persue this kind of thing strictly for the educational benefit but
I would be careful about putting too much expectation into what you will be
able to do with it once you have built it.

Chris

-- 
Chris Elmquist | mailto:chrise at pobox.com | http://www.pobox.com/~chrise