[Taxacom] GPS units that record the time a waypoint was taken

Frederick W Schueler bckcdb at istar.ca
Thu Mar 19 08:37:08 CDT 2009

Mike Dallwitz wrote:
>> If the unit says that the accuracy is 20 m, but over a long period at 
>> the same point (or repeatedly moving away and coming back to it), it only 
>> fluctuates by 3 m, does that mean the accuracy is really 3 m?

* I can't speak to real accuracy, since my only reference is topo maps, 
but for precision, over years of measurements, the "accuracy" reading on 
the old Garmin 45, for departure and arrival readings in our driveway, 
was similar to the standard deviation of the readings (circa 20m; see 
Schueler,  Frederick W. 2000. Navigating as Naturalists with the Global 
Positioning System. Trail and Landscape 34(1):35-40).

I use 3 times the usual "accuracy" reading of the unit in the ACCURACY 
field of my database, but, along with time, the eTrex doesn't download 
the accuracy.
> See http://en.wikipedia.org/wiki/Accuracy_and_precision

             Bishops Mills Natural History Centre
           Frederick W. Schueler & Aleta Karstad
        RR#2 Bishops Mills, Ontario, Canada K0G 1T0
     on the Smiths Falls Limestone Plain 44* 52'N 75* 42'W
       (613)258-3107 <bckcdb at istar.ca> http://pinicola.ca

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