2 Magellan's 2 sets of numbers

[Akeybabe]

I have 2 older Magellan units for caching. I'm not sure which one to trust, or to buy a newer model.

1st is a Magellan Meridian Platinum and the other is a small explorist 200. The explorist 200 is much eaiser to use, I use it more but the last couple of caches I have planted, I have had a couple of comments about the coords. being off, I do let the GPS set for a moment to settle it's numbers. I did a small test and set the units up side by side on a table, and the N. coords matched but the W. coords were off by a few numbers.

 

Also can someone explain "Map Datum"? Mine is set to WGS84 how do I know if this is correct??

 

Thanks again you all have been a lot of help

Eric..

[+trainlove]

The Datum is the model of the Earth that a map or coordinate is based on. We all use WGS84. If you are using anything different your GPS may display a coordinate that's hundreds of meters 'wrong'.

 

Magellans can have problems if your secondary coordinate (position screen and left or right arrow) used a different datum, even though it's just displaying an equivalent position.

 

Magellans also can have a problem if you were just moving. The best thing to do is to turn it off and on again and wait for a 3D fix, and the EPE (estimated position error) to get small, then trust that reading.

 

+/-5 or 6 in the least significant digit is to be expected as the GPS system has a 95 percentile of being correct to +/-10 meters.

 

Check http://ray.jerome.jobs.googlepages.com/gpshints for hints on using a Magellan.

 

edited to add:

I think the secondary problem mentioned above really only happens if you try to project a waypoint.

 

Ah, I didn't think this post got through. The timeout of a public library computer occurred about 15 seconds after I pressed the complete post button.

 

P.S. You metion putting them on a table. I assume you mean a picnic table out in the open and not something indoors? Your GPS has to be able to see the satellites in order to be able to tell you where it thinks it is.

Edited July 10, 2008 by trainlove