Terry, et al,
Back ten years ago, maybe more, Walter Holmes, an engineer with Compaq,
was going mobile packet using a Radio Shack laptop (you know, 64 KBPS of
RAM and 2" X 6" LCD screes) and TNC. He strapped the taptop to the
steering wheel (or so I'm told) and I worked him going between houston
and San Antonio.
Later the same year, my XYL (WB5WXY) and I made a trip thru the south, up
to DC, over to Ohio and back down to Graceland and back to San Antonio.
We had packet mobile...not just mobile, but a mobile BBS running on the
same type of Radio Shack laptop that Walter used. We would have folks
here in San Antonio and around the state (of Texas of course) send us
E-Mail at specific BBSs along the route. As we passed thru the areas, we
would have the BBS automatically query the local BBS for E-Mail and pick
up our E-Mail.
About two years later, after I began running TCP/IP on 2M (1200 baud) and
70 cm (19.2 KBPS) I ran TCP/IP mobile on 2M in and around San
Antoino...had to stay close to the gateway.
All of the above worked.
I've also worked backpack TCP/IP...this would be a real Hoot using a
PalmTop and micro-TNC at 9600 BPS.
Have fun guys and keep on expermenting.
Walt/K5YFW
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On Wed, 11 Feb 1998, Terry Dawson wrote:
> Darxus wrote:
>
> > 1st concept is a wearable computer.
> >
> > Second concept is the AX.25 internet connection concept -- hook up a
> > portable HAM radio to a wearable, and connect via radio waves (TCP/IP
> > encapsulated in AX.25) to a computer at your house, and route your
> > connection through to the internet via a dialup modem.
> >
> > Third concept is encapsulating phone calles through a network like the
> > internet. You could do funky things like calling a local number, which
> > happens to be a computer, which connects to a remote computer, via the
> > internet, in the area code of the phone number you wish to connect to, and
> > encapsulates your phone call. No charge.: (login) session opened for user
> > darxus by darxus(uid=0)
>
> Most of these things have already been demonstrated as feasible in
> one fashion or another.
>
> Wearable computers are a reality in a not particularly utilatarian
> fashion already.
>
> AX.25 Internet connections have existed for some time. I've known
> people who have operated packet radio in a mobile capacity, bringing
> the two together is trivial.
>
> I've done voice over IP over AX.25 myself. I used the gsm speech
> compression algorithm and a fairly conventional linux based 4800bps
> packet radio configuration. It was store and forward style, ie
> push to talk simplex operation, so they were "walkietalkie" type
> communications, but with only 4800bps simplex packet radio you don't
> get much option :)
>
> There is no good reason why the addition of a silence detection
> algorithm and enough processing power to do the compression quickly
> couldn't produce a workable system fairly easily. Mind you, if you
> have a perfectly good radio system in place, you'd have to ask why
> you'd bother :) It'd be much simpler to just do an analog phone
> patch.
>
> > There are, of course, problems. Getting a voice stream to a phone line
> > (which could actually be easy, I haven't looked into it), the current
> > bandwith constraints of AX.25 and the bandwith requirements of
> > bidirectional voice straeming.
>
> There are no inherent bandwidth constraints for AX.25, it is the radio
> and the modem that are the largest constraint. Running IP over AX.25/UI
> mode is moderately efficient with large packet sizes.
>
> Terry
>
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