Re: GPS accuracy and a site to generate a map of findings
- From: Jack Erbes <jackerbes@xxxxxxxxxxxx>
- Date: Fri, 17 Nov 2006 08:38:36 -0500
DJW wrote:
My friend brought over their hand held Garmin GPS unit. Offhand not
sure of model but if it matters I can find that out. We were in a
northern USA location and had large trees around us. It seemed to see
three to six satellites that kept changing.
If it was one of the models with the SiRF III chip set it will receive and process up to 20 channels of satellite data. It only displays 12 channels so when it is processing it display some of the channels intermittently. I'm not sure of the logic but it looks like the pr
The coordinates came up but
the Plus and minus would be between 18 to 25 ft. Does that mean that we
were not actually getting very good accuracy as to where we were
standing.
That *is* good accuracy. That value will often get as small at 12 or 14, maybe even less, when you are standing without movement. But as soon as you start moving the figure will increase a little and factors like vegetation or your hand blocking the antenna, getting your body between the GPS receiver and the mid latitudes (where more of the satellites will be) will affect the EPE value.
I thought that I heard that the government purposely made
them just a couple of feet off for security purposes in case a evil
person wanted to send a cruse missile off and out lol.
That program was called Selective Availability and has been turned off for some years now. There are better receivers than the consumer grade models discussed here for the most part. Those are used by the military, surveyors, etc. Or even consumers if they don't mind the bulk, weight, and cost.
Also is there a free site on the web where I could put in the
coordinates we got and be able to see and or print out a map.
Google earth.
If the accuracy really was like 20 feet off was it just our location.
How do those people who look for buried treasure ever find it in those
setup treasure hunt games?
It would have been a 20 foot radius around the receiver location at that moment in time. The people have brains, eyes, and are looking for clues and "flagged" or good hiding places. Or good luck and metal detectors for real treasure..
Jack
--
Jack Erbes in Ellsworth, Maine, USA - jackerbes at adelphia dot net
(also receiving email at jacker at midmaine.com)
.
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