[Xastir] System cost options

[Tom Russo]

On Tue, Jun 26, 2007 at 09:06:18PM -0500, we recorded a bogon-computron collision of the <RiverRidge at CenturyTel.net> flavor, containing:
>  Thanks for the suggestion. 
>  I noted in the MicroTrak 300 manual, ".......power output in the range of 
>  300 mW, and is capable of operating at extremely long ranges .......".  My 
>  understanding of the problem with Garmin Rinos was that they were low power 
>  -- 1W or 5W -- meaning that the transmission distance was too short to be of 
>  much use.  
>  Is this an apples and oranges issue?  What am I missing?  (And please feel 
>  free to point out my misunderstandings.... I am VERY new to this <grin>.)

That depends on the local APRS infrastructure and how it's loaded.  That 300mW 
might be enough to hit a digipeater if your terrain is right and your 
infrastructure is built up enough.  Once it gets digipeated, the power of the 
original tracker is less important.  There is no infrastructure you can 
leverage with a Rino, and it's strictly line-of-sight between tracker and 
receiver.

I'm pretty sure that the MicroTrak doesn't have a receiver, which means it'll
transmit blind --- it won't be able to keep its mout shut when the channel's
busy.  This could be a significant downside, but is not necessarily bad.
If you have a lot of APRS traffic in your search areas, there will be times
when the flea-powered MicroTrak will transmit while other traffic is on the
channel, and it won't be heard.

At base, with the laptop, you need a TNC and a radio --- it needn't be a
D7, and that would actually be a waste of money.  A KPC3 and an HT or
mobile rig would be adequate, and would be much cheaper.  Where a D7 (or D700)
shines is as a stand-alone unit, because it can decode APRS as well as transmit
it --- so your field teams can receive APRS messages and can see position
reports of other teams on their GPS screens.  You don't need that at base,
because you're using a computer with APRS software there, and that software
would be doing all that for you anyway.

If you can't afford 12 D7's, (that's a lot of green), you could buy a few and 
deploy cheaper, less fully-featured trackers like the MicroTrak on some teams.
You needn't even buy GPS units for all of them, as you can set yourself up
to use the personal GPS units of your field teams with the APRS tracker ---
it can still be used even while wired up to the tracker.

The D7 is merely a convenient, relatively rugged, and easily set-up unit. You
pay for that convenience.  

Remember, too, that you needn't get the entire system running at once, and
you can mix and match true APRS trackers with Rinos.  Getting a usable
small set-up as a proof of principle, and getting familiar with using it might
be a way of encouraging more donations or grant money.

The Rino is pretty limited, and you pay for the limitations, too.  But even with
a full APRS set-up, you can always add Rinos to the mix, too --- Xastir can
be used with both simultaneously, so long as you have a suitable Rino in base
that can poll the Rinos in the field. 

Your options for building out a system are pretty wide open.  If you want
a consistent, stable, and very usable system you can go the pricey route with
every team having a D7, but if you're limited on cash, you can set up a more
varied kit of equipment to get the job done.

>  Richard Polivka, N6NKO wrote:
> > Another possibility is to look at Byonics.com. They make units that work 
> > great for APRS trackers.

-- 
Tom Russo    KM5VY   SAR502   DM64ux          http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236 AHTB#1 http://kevan.org/brain.cgi?DDTNM
"And, isn't sanity really just a one-trick pony anyway? I mean all you get is
 one trick, rational thinking, but when you're good and crazy, oooh, oooh,
 oooh, the sky is the limit!"  --- The Tick