[aprssig] The best resolution of position from APRS

Wes Johnston aprs at kd4rdb.com
Tue Jan 3 22:07:51 EST 2006

I just ran an Opentracker hooked to a Dallas one wire weather staion for
60 hours on a 4aH battery.  Ht was an old no frills alinco 5w HT on the
5w setting.  Interval was every 10 minutes with comment (ie voltage in
comment) every 30 minutes.... so 8 packets per hour for 60 hours.  I'm
absoultely sure it would last A LOT longer if the HT was able to be
powered down.  We're looking at deploying these portable wx stations for
days at a time in the SC state guard.  The longer they last on
batteries, the happier we'll be.  Last year a train car carrying
cholorine gas derailed and they started wanting portable weather
stations to kinda know what the wind is doing.

I gotta say, I'd really prefer the metal case like TNCx with 20amp power
switching in it.  I find the tiny track/opentrack case with de9's on
each end a little clunky, but cute.  What starts as a small cute case
ends up being 3-1/2 inches long by the time you get the 9pin hoods on it
and there aren't any screws to secure the de9's with.  I'd rather see
the serial and radio ports both come out the same side of the unit, and
as I mentioned a moment ago, I'd *really* like the metal case with power

I have the power switching open track in my wife's car at this time
running off her car battery and wow, it' a blessing... no need to switch
anything on or off to save battery... I just hooked it directly to the
car battery and it comes on as needed.  My GPS is motion (vibration)
activated and goes to sleep when the car isn't moving.  The open tracker
runs all the time and the 50w 2m radio only comes on 2 seconds before
transmitting a position... neat!  For the time being, I've got my mother
in law looking for a metal cookie tin to mount the open tracker in.


scott at opentrac.org wrote:
>>The best resolution is to use compressed mode. Unfortunately, several 
>>months ago, Bob said that no one should use it at all, lest the be 
>>tempted to use it on an Object or Item which wouldn't be 
>>decoded by the 
> That's OK... in a few months, everyone can just buy one of my new trackers.
> =]  They'll already do compressed items/objects, direct or third party, with
> Garmin symbol translation (plus a number of custom symbols on supported GPS
> receivers), altitude extension (goes in the Garmin elevation field) and
> comments.  Doesn't bother me at all if Kenwood doesn't want to fix their
> firmware!
> Speaking of the new project, I've been meaning to set up some sort of poll
> about the form factor.  Would you rather see something like the OT1x layout
> (plastic case, inline DB9s on each end, slightly larger than the TinyTrak or
> original OpenTracker), a larger plastic case with a battery compartment
> (either a cheaper and less noise-prone 9-volt setup, or more complicated
> dual AA that might be able to run a GPS for several hours), metal case like
> the TNC-X or KPC-3 plus mounting flanges and the ability to control a 20-amp
> load (either for radio power control or remote control), or something else?
> There could of course be more than one version eventually, but for now I
> need to concentrate on getting one board ready.  The current prototype board
> fits (er, almost) in the inline plastic case, which is certainly the
> simplest and cheapest way to go, but except for the fact that it has locking
> connectors, introduces all of the same mounting problems as the TT3 or
> OpenTracker.
> I've done a couple of prototypes for a metal case version with power
> control, leaving holes on the PCB for direct soldering of 12 AWG wire.  It
> occurs to me that a screw-down terminal block might be an option as well -
> ought to handle 15 amps at least, and would provide convenient telemetry
> connection points.  Anyone tried using one of these as a power connection in
> a mobile application?  I worry that it might not be secure enough.
> Other suggestions?
> Scott, N1VG
> http://n1vg.net/opentracker
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