WGS 84 Datum??

[Guest Barb48]

What is WGS-84 datum?

I have a Magellan Campanion attached to a Palm Vx. I used it yesterday and had trouble finding the cache because my GPS readings changed.

This cache was hidden in a park on hilly terrain. Is there something I'm doing wrong?

Someone suggested my GPS didn't use WGS-84 datum.

[Guest RXQ]

The default setting for map datum is WGS 84. People have reported problems when trying to line up there coordinates with a topo map, like the ones used on topozone. Their map datum is NAD 27. There can put you off by 200 feet or more. The Cache position listed is WGS 84 but when you look up the position on topozone it will be incorrect if you don't convert it to NAD 27. Hope this helps.

[Guest cache_ninja]

howdy, that was me ,

i wasn't suggesting your unit doesn't use the WGS-84 datum, just that it might not be set to that datum at the moment. If you just search around in the options/setup on the unit, you should be able to find a datum section on there. Its natural and expected for coordintes to fluctuate/move etc. You seemed to say yours were very different than the cache location, and the most common cause of this is the datum setting. If its not on WGS-84 you will always be off etc.

 

anyone know how to check it on the palm?

 

thanks

c/n

[Guest fairbank]

As long as you have your GPS set to WGS84 datum when you are inputting the cache coordinates given on the cache pages then your OK. You can then switch to any datum you want (that includes the area your coordinates are in) and your "goto" page will take you to the same spot. However, if your going to also use a map to help in your search, then you must set the GPS datum to the same datum that the map uses. It doesn't have to be WGS84.

 

Eric,

Topo map help page:

http://www.geocities.com/fairbank56

[Guest bacpac]

In my opinion the significance of Map Datum is poorly defined in the literature of some GPS manufacturers.

 

I assumed that the default map datum of my Garmin GPS12 would be the same as all the USGS topos I owned. It is not. I have not seen any maps that use WGS-84 datum, but I assume there must be some.

 

I advise each GPS owner to study their maps and the section on map datum in their owners manual. GPS software has not advanced to the level of PC software that facilitates custom user interfaces.

[Guest abeyoni]

I'm ready to hide a cache. In the 'how-to'

section it says to post cache location in

WGS84 format. how do i get that info from

my eTrex Summit? for the caches i've found

i've only used the long/lat info.

[Guest bacpac]

Your GPS probably came with the WGS-84 datums set as the default. There are options for displaying a variety of coordinate formats as well. On my Garmin the format option I select for posting to this site are hddd mm.mmm.

 

There should be a selectable coodinate format as well as selectable map datums.

 

Good luck.

 

A good site with tons of help is available at http://joe.mehaffey.com

 

[This message has been edited by bacpac (edited 04-01-2001).]

[Guest Cape Cod Cache]

Congrats on getting a cache out abeyoni.

World Geodetic System 1984 is a method of defining Lat/Lon. It's the most recent definition of Lat/Lon, and GPS being used originaly for aviation and marine use, it's the default. It also translates to other datum systems well.