[aprssig] Looking to borrow some Garmin units

Doug Faunt N6TQS +1-510-655-8604 faunt at panix.com
Thu Dec 15 13:20:21 CST 2005

Hi Scott,

I've got an ETrex Vista, running software version 3.60,
and a Geko 301 (and I can't figure out the software version), either
of which you can borrow.

73, doug

   From: <scott at opentrac.org>
   Date: Wed, 14 Dec 2005 22:11:44 -0800
   Thread-Index: AcYBPmvu5KonRgx6RJSjbASJVwp4FA==

   Those of you who follow OpenTracker news probably already know that I'm
   working on a follow-on to the OpenTracker, tentatively called just Tracker2
   for now.  It's a receive-capable device, and has the ability to plot
   received positions on a GPS receiver's map.

   In addition to outputting the usual NMEA $GPWPL format, it can also speak
   Garmin binary protocol.  This means that stations show up with appropriate
   symbols (limited of course to the receiver's symbol set), elevation, and
   comment text.

   The trouble with Garmin binary protocol is that it isn't really one
   protocol.  They've got about a dozen different waypoint formats, for
   starters, and I can only test with what I've got on hand.  The protocol
   varies not only with GPS model, but also with different software versions
   for the same model.  I'm hoping to borrow assorted Garmin units for testing
   - I need units with serial interfaces (not USB-only like some of the newer
   models), the ability to display waypoints (not headless units), and
   preferably the standard round 4-pin or flat eTrex-style connectors, unless
   there's a cable to go with the unit.

   If you've got a unit you can spare for a couple of weeks, let me know the
   model number and software version and I'll tell you if I can use it.  I'll
   be happy to send along an OpenTracker kit or a bag of Powerpoles with the
   unit when I return it.

   The protocol's not the only issue, either - there's lots of undocumented
   stuff to test, like what characters are allowed in the comment field, what
   symbols are supported, whether the unit beeps or displays a message when
   transferring data, and so on.  Garmin absolutely refuses to provide any
   programming support beyond the interface spec document, so it's got to be
   done the hard way.

   Anyway, here are a couple of screen shots from a Tracker2-connected GPSmap


   The first shows a map screen in the LA area, with a number of stations
   visible.  Digis are antenna towers, unsupported symbols are green dots.  The
   second image is the waypoint detail screen for a station.  In this case, the
   comment text had my email address.  The 'at' sign isn't supported, so it was
   replaced with a '-' to keep it from all running together.  There was also an
   /A=000234 altitude string in the comment, which was stripped out (to reduce
   clutter and save comment space) and placed in the elevation field.

   The prototype unit currently decodes just about everything except
   maidenhead.  That includes standard positions, compressed positions, Mic-E,
   objects, and items (which can also be compressed).  Unfortunately there
   doesn't seem to be a way to delete individual waypoints, so a 'kill' command
   just changes the symbol to a skull and can optionally move the waypoint to a
   'graveyard' somewhere, which at least makes it go away if you're in the
   proximity-sorted list.

   I'm hoping to have a production version ready in the next three months.
   I've still got to decide what form factor I want to do initially - the
   current version fits (well, almost fits) in the same case as the OT1x.
   Other possibilities are a metal box that'd be better suited to vehicle
   mounting, or a version with a battery compartment that'd be more useful for
   man-portable operation.  Each option has its problems, but if you have any
   particular preference, or any other suggestions, let me know.  The Alinco
   DR-135 internal option is still in the works, held up due to difficulty
   finding anyone with the connector tooling.

   There will also probably need to be at least one button on the tracker
   itself, to initiate certain events.  I'd like to be able to create waypoints
   with the GPS receiver and have them transmitted as objects, but it
   introduces some design challenges.  For one, downloading the waypoint list
   from the receiver causes it to beep loudly and display a message on the
   screen - in other words, it's not something you want it doing every 30
   seconds on its own.

   More to come later...

   Scott, N1VG

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