Affordable GPS systems

[Una Smith]

Matt Davey wrote:

>                           the group we borrowed [the GPS unit] from were
>taking the co-ordinates from the gps to map where certain plant species
>exist in the forests for future reference, i for sure would not like to be
>the person in the future wondering around the forest in a few years time
>looking for plants at imaginary co-ordinates.

Exactly.  To use GPS as a substitute for checking maps, I think at the
least I would want to know the date and time, the model of GPS unit and
its precise capabilities, how many sats contributed to the coordinate
data, and the local reference datum in use by the unit at the time.  All
so that it would be possible, with a little research and programming,
to work out a correction factor to match the GPS coordinate to the right
spot on a real map.

Of course, recording coordinates from a map has similar problems, so it
is important to be explicit about what map was used, and if possible to
archive a copy of that specific map.

        Una Smith               Department of Biology
                                Yale University
        una.smith at yale.edu      New Haven, CT  06520-8104  USA