[Xastir] More system questions

[Curt, WE7U]

On Wed, 27 Jun 2007, Tom Russo wrote:

> A portable digipeater-in-a-box, however, can be deployed at a mission as
> needed --- it needn't be man-portable, can be in a rugged waterproof
> container, and with a mast, big battery, and beefy mobile rig could be
> very effective.  Our SAR Support team has one and can deploy it as needed
> (which in our case isn't often).

*) Steel ammo-can.
*) Large gell-cell.
*) Mobile antenna mounted to the lid, perhaps a 1/2 wave antenna so
   that it doesn't require a ground plane.
*) 2-meter handheld radio.
*) Kantronics KPC-3+ TNC, set up to digipeat.
*) Perhaps a chain to lock it to a tree in case a stray hiker finds
   it during the mission.

One problem with this setup is that you have to allocate a resource
to put it into place and another to retrieve it after the mission.
Perhaps someone to replace the battery during a longer mission.


> I am still of the opinion that the SARn-N idea could work, but has the
> potential to jam up a channel quickly as every field team digipeats every
> other team's data.  I am waiting to be proven wrong, at which point I'll
> gleefully eat my words.  At this point I have no way of doinng the
> experiment myself, as none of the readily available tracker units can do
> it anyway.

I figure 10-15 teams in the woods, transmitting roughly every 3-5
minutes, with some of them being in range of others and some not at
any given time, won't be that much of a load.  At least with the
WIDEn-N anti-duping algorithm and using the preemptive digipeating,
it should work well.  Yea, needs to be proven in real experiments.
If I get my three T2's on the air I'll try it on another frequency
and bump up the rate quite a bit to try to figure out what the
practical limits are.  Can also get other people with regular APRS
non-digipeating stations on the same frequency for the experiment.
There are other T2's in the area as well, a few T2-135's in
Alinco's, and at least one other OT2M up in Canada (which is part of
our backyard).  Maybe we can get together for a combined experiment
at some point.

--
Curt, WE7U.   APRS Client Comparisons: http://www.eskimo.com/~archer
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