I've got a Garmin GPSMap 420 on my small sailing boat, and I've tried
exporting tracks etc. The data seems to end up on the SD-card as a
file called "userdata.adm". Unfortunately, no GPS data converter
program I've found seems to support this format, and a Garmin
representative in Denmark says that Garmin have no program to export
it into anything world readable. I've asked for the file format specs,
but my hopes are not up.
Would it be interesting for any one of you coding wizards to try
making sense of this file format? If so, I can supply you with files.
For example, it might be interesting to wipe all tracks etc. and try
exporting the data anyway, hopefully getting a default file,
thereafter create exactly one known waypoint and export the data for
file comparison, enable tracking and walk exactly 1 meter straight
north and export again etc. If it's interesting for you, drop me a
line at bjornar.b.larsen ¤a¤t¤ gmail.com.