gps recommendations?

I am going to update some trail maps of a local park, and have seen
examples of gps units and software that talk to topo maps and merge
waypoints to the map, etc. What are these features called? What would
be a few minimum models I should look at?
gr

gr wrote:

I am going to update some trail maps of a local park, and have seen
examples of gps units and software that talk to topo maps and merge
waypoints to the map, etc. What are these features called? What would
be a few minimum models I should look at?

For the most part, the abilities you are looking for are a function of
software, rather than of the GPS receiver.

The minimal features you need in the GPS receiver are (a) creating an
automatic "track log" that records where you went, and (b) connecting
the GPS receiver to a computer, so that the software can make good use
of the information about where you went.

Among the numerous models made by Garmin, the minimum models seem to be
the "plain" (yellow) eTrex (as opposed to the eTrex Summit and eTrex
Venture, which are more expensive) and the Geko 201 (colored puke-green)
(as opposed to the (yellow) Geko 101, which appears to lack the ability
to connect to a computer).

I'm less familiar with the Magellan products, but, after puzzling over
their Web site, it looks like the Explorist 100 and 200 do NOT have the
ability to connect to a computer, but the Explorist 210 DOES. And it
also appears that they have a basic model called SporTrak which seems to
be analogous to the Garmin eTrex in that the "plain" SporTrak meets the
minimal requirements and then they have a series of more expensive
models (SporTrak Pro, SporTrak Color, SporTrak Map, SporTrak Topo, etc.)
with additional features.

Lew Lasher
Cambridge, Massachusetts and Stowe, Vermont

gr wrote:
I am going to update some trail maps of a local park, and have seen
examples of gps units and software that talk to topo maps and merge
waypoints to the map, etc. What are these features called? What would
be a few minimum models I should look at?
gr

You're opening up a big can of worms...

Simple way.
Most GPS units will record a "track" or "trail" of where you have been, and
you download that onto a computer for subsequent re-use.
Most will let this trail be overlaid on a Map held in the computer (though
you'll need the map from somewhere to start with), which can subsequently be
printed out.
Tools such as GoogleEarth will let you view and print the trail overlaying
an aerial photograph.

If you save the track, you can then load it into another GPS and display it
on the GPS' screen (overlaying whatever maps that unit might have, or as
just a trail if the GPS is not a mapping unit). There are a few issues
translating tracks from maker to maker, but its not overly difficult.

( In this context Most = GPS with computer interface. There are a few models
around which lack the option of computer interface, avoid those.).



Advanced way.
Make transparent map layers which can be loaded into a mapping GPS unit,
overlaying the maker-supplied maps with your trails.
This gets you into quite heavyweight computing. I'm reasonably OK with the
basics for a Garmin device, and I believe there are similar methods for
Magellan. If you've a lot of stuff, or are just interested in doing it, the
results can be very useful.
Essentially, one needs to record the track (above), then use various bits of
public domain software to edit the trails and finally compile a map. That
map can then be uploaded into a mapping device. Start by looking at
www.cGPSmapper and www.Geopainting.com . The learning curve is steep.






--
Nigel Cliffe,
Webmaster at http://www.2mm.org.uk/