At 06:49 AM 8/13/02 -0700, you wrote:
>Unless one is using something like a calibrated Trimble (about
>$15,000USD), accurate GPS readings, forest or no, will be unlikely
>until the distortion chips are removed.
>
>Bernie Krause
None of the units have distortion chips. The distortion signal,
proprietary of the US Military, that was intended to destroy accuracy was
removed years ago by executive order of Bill Clinton, and remains set to
zero today.
The very accurate Trimble units for surveying have a base station, set at a
calibrated exact location, which broadcasts its GPS location to the field
unit on a separate frequency. This (when the distortion was in effect,
before Clinton) allowed the field unit to subtract the errors and thus
provide immediate accurate data. Now, totally unnecessary.
If you are getting bad locations (more than 10 meters off) from ANY units
today it is a signal problem, and external antennas might help.
The altitude has never worked properly, and typically give hilarious values
- - -as we drove around the coastline, of sometimes negative 200
meters. Glub, glub.
Marty
my very best,
Marty Michener
MIST Software Associates
PO Box 269, Hollis, NH 03049
coming soon : EnjoyBirds, bird identification software for all AOU area.
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