Appropriateness of the linear correction method for GPS positional fixes in wildlife studies
Casaer, J., Hermy, M., Verhagen, R. & Coppin, P. 1999: Appropriateness of the linear correction method for GPS positional fixes in wildlife studies. -Wildl. Biol. 5: 125-128.
This paper describes the results of tests performed to evaluate linear correction of GPS measurements as an alternative to differential correction of GPS positional fixes. Differential correction requires information which is not provided by the existing animal-borne GPS systems for smaller mammals. Therefore, linear correction, by means of a second GPS rover, has been suggested as an alternative to differential correction. To test the accuracy of linearly corrected measurements, we compared the position estimates of raw, linearly corrected and differentially corrected GPS positional fixes with the true (known) geodetic position. The tests indicate that the accuracy of linear correction is highly unstable and is related to differences in the satellite constellation used by the GPS receivers. Linear correction is consequently strongly discouraged. If differential correction is not possible, we recommend the use of raw GPS measurements, of which the error is well known and more predictable.
Key words: animal-borne GPS, GPS correction methods, mammals
Jim Casaer, Martin Hermy & Pol Coppin, Laboratory for Forest, Nature and Landscape Research, Vital Decosterstraat 102, B-3000 Leuven, Belgium - email : jim.casaer@agr.kuleuven.ac.be
Ron Verhagen, Evolutionary Biology Group, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium
Received 1 October 1997, accepted 1 December 1998
Associate Editor: Tomas Willebrand