On 13 Dec 2006 11:40:00 -0800, "Marco Leon" wrote:

When we look at a GPS error value in a so-equipped GPS, does that value
reflect *both* the vertical (i.e. altitude) and the horizontal
component? Can a separate value for each be determined?

The reason I ask is that in firing up my Garmin 496 (an early Christmas
present, comments to follow in another post ), I noticed the altitude
initially register at 100 ft below actual then right itself after a few
minutes. All of this happened while the horizontal location did not
noticeably move (had it fully-zoom by the way) which led me to believe
that the error can be different from each other at least initially.

Marco

You can try to improve vertical accuracy using calculations from one
of the following websites but you need to know if your GPS is already
correcting or not!

http://sps.unavco.org/geoid/

http://earth-info.nga.mil/GandG/wgs8...0/intptW.html?