Dr. �ET�N: In grad-school, did a field test that compared the elevation measurements obtained from a GPS unit to those obtained from a handheld altimeter. The GPS unit was very accurate for latitude and longitude but very inaccurate for elevation. The elevation readings varied by +/- 100 feet from point to point. The handheld altimeter was much more accurate. One person suggested that the reason the GPS elevations are inaccurate is because all satellites are overhead - there are no satellites underneath you.
I'd use a handheld altimeter for field elevation measurements.
I've attached a PDF file that provides details of the two devices and
summarizes the results. [List-members: if the attachment is not
included in the post to the list and you would like a copy, send me an
email.]
Regards,
-- David Stinchcomb
Texas Department of Health
M.A.Geo. 2002, Southwest Texas State University
======================
Mahmut �ET�N wrote:
> Dear list members,We are planning a field survey. In the field, we
> have many deep groundwater wells. We will determine both position and
> elevations of each well by using a GPS device. Do you think that we
> may measure the elevation by using GPS. What about the precision or
> error we are subject to? Could you recommend us a device with some
> specifications. Surfing Internet, I found GPS devices of GARMIN,
> however no specifications on elevation measurements.Every kind of
> suggestion is welcome.Yours Sincerely,Dr. Mahmut
> CETIN-------------------------------------------------------------------------------
>
> Associate Prof. Dr. Mahmut CETIN
> Department of Agricultural Structures and Irrigation
> Faculty of Agriculture
> University of Cukurova
> 01330 Balcali-Adana/TURKEY
> Tel: ++90 (322)338 6877 (Direct)
> ++90 (322) 338 6318 (Switchboard, ext. : 25)
> Fax: ++90 (322) 338 6386
> E-Mail: [EMAIL PROTECTED]
GPS_vs_Alt.PDF
Description: Adobe PDF document
