From: Kenny Reed (kreed@pintoeng.com)
Date: Wed Dec 21 2005 - 15:21:42 PST
that is basically what the gps of today does. it has to have at least 6
sat. in its "view". it will take the average of the three strongest sat and
that is your coord. for a topo shot it takes a 5 sec shot. for control
points it takes a three min shot as long as your base station is on a known
control point like a usgs control monument. to set a control point that
isn't on a certain grid system then you can send the kinfo the gps gathers
in to a site called opus. they require that you do a two hour record in the
morning and then two hours in the afternoon also. that is a min. if you
have 3 hours and 59 mins then they will not even look at it twice. then you
can have the highest accuracy on that certain coord system. the reason the
elevation of a gps is the worst for accuracy is the sharp angle that most of
the sat. signals are coming down at. the signal for sat. around here is the
strongest in the morning and at its weakest from 1130 to about 130. that is
around here anyway. that will be different in other places since the
rotation of the earth more or less changes the viewable skyline.
Kenny Reed
1968 M35A2 W/W, Whistler
Hopefully Ring Mount and .50 cal soon
----- Original Message -----
From: "J" <W7LS@blarg.net>
To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
Sent: Wednesday, December 21, 2005 4:53 PM
Subject: [MV] Getting the higher resolutions on GPS
> One simple trick some GPS use is just plain old averaging positions over
> time. If you just sit there and average all the positions the GPS says
> over a long time, like hours, you can get down to a few millimeters.
> Surveyors have this kind of equipment. Any one given GPS coordinate
> reading is prone to the adversities of the atmosphere, and the users
> position will appear to wander about, in a 10 meter area. Over time, your
> true position will be in the center of all that wandering. Jim
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