I Have a Garmin Etrex Legend i have used and enjoyed for a while but I never paid much attention to the coordinates now I want to use it in conjunction with UTM coordinates but I am not sure what setting I need to put it on. there are two UTM settings in the units options one is "User UTM" and the other "UTM UPS"

and for those of you who know almost everything. the option under setup, units "map datum" what is that and is it possible I may need to change it if I am using maps in another country such as mexico (supposedly the mexican maps I have are UTM)

I Have a Garmin Etrex Legend i have used and enjoyed for a while but I never paid much attention to the coordinates now I want to use it in conjunction with UTM coordinates but I am not sure what setting I need to put it on. there are two UTM settings in the units options one is "User UTM" and the other "UTM UPS"

and for those of you who know almost everything. the option under setup, units "map datum" what is that and is it possible I may need to change it if I am using maps in another country such as mexico (supposedly the mexican maps I have are UTM)
For the UTM setting, just use the UTM UPS.

<DT>datum: <DD>A set of parameters and control points used to accurately define the three-dimensional shape of the earth. The datum defines part of a geographic coordinate system that is the basis for a planar coordinate system. For example, the North American Datum for 1983 (NAD83) is the datum for map projections and coordinates within the United States and throughout North America. </DD><DD>(Source: ESRI ArcGIS 8.1 glossary)</DD><DD> </DD>As for which datum to use, that depends on the map you're using as a reference. The most recent datum for the USA is WGS84, but other commonly used datums are NAD83 and NAD27. Most USGS topo maps in the US are still NAD27. For your Mexico maps, you'll want to look at the bottom of the map where the map scale and legend are located for some text indicating the datum.

Nate

I don't know about a Garmin, cause I have a Magellan.. But if you don't get an answer here, then try www.geocaching.com forums.. Someone there has your answer

thanks

and for those of you who know almost everything. the option under setup, units "map datum" what is that and is it possible I may need to change it if I am using maps in another country such as mexico (supposedly the mexican maps I have are UTM)

I do know about map datums. Generally your GPS should be set to WGS84 (World GLobal Sytstm 1984). But If you are using a topo map, or any map for that matter you need to set your GPS to the same Datum as the map.. On USGS topo maps it is noted in the info at the lower left corner of the map. Usually NAD 27 (North American Datum 1927). If you don't have your GPS set to the proper map datum your position on the map wll be incorrect. It doesn't matter what sytem you are using either .. Both UTM (Universal Transverse Mercator) or Deg.Min.Sec's. i don't know about a GArmin, but my Maggie Gold will display both types of co-ord system info at the same time.