NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: G Becker
Date: 2010 Nov 23, 05:09 -0800
there are a few reasons why your gps is off.
1.) your gps is a "recreational grade" unit. If the wind was at your back, all the stars lined up, and you had your lucky rabbits foot with you.... you would be lucky to get within 3 feet / 1 meter of a point.
2.) if the satalites were in a poor distribution (bad angles in the horizon & low number of satalites) in the sky you would have a poor PDOP. Bad PDOP usually will give you bad sollutions. Add a bad PDOP to a recreation grade GPS and you get gobbeldy goop.
A $30,000 "survey grade" GPS can only get within a +/-6mm of a point.
The cost of a GPS unit is based on the quality of the software solution & internal chip in the GPS unit. Generally speaking, all GPS units have the same antenna. The BIG, HUGE difference is the processing chip and the internal software.
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