Precision and Accuracy of Global Positioning Augmentation Systems and their Application to Geoarchaeology

Abstract

Free global positioning data correction products from government, university, and even commercially-managed global positioning augmentation systems have made cm-level positioning data cheaper than ever before. That said, threshold costs associated with receivers compatible with these data products continue to present financial challenges to geospatial field workers who do not have the budget for many (or any) of these $5000-$10,000 receivers. As such, demand persists for cheaper, position-correction alternatives. This study investigates one such alternative. In the experiment, I compare the accuracy of positional data from a consumer-grade global positioning receiver, a mapping-grade global positioning receiver, and the same data augmented by correction factors from two other, identical receivers acting as base stations. I hypothesize that correction factors from an identical receiver will increase the precision and accuracy of a data set, but correction factors from a different receiver will not. Accuracy of both horizontal and vertical coordinates is tested through root-mean-squared-error calculations. Results show that augmentation with either set of correction factors does not increase precision or accuracy. Further research on the particular sources of error in the survey environment as well as on the algorithms currently utilized by augmentation systems may reveal how the methodology used here can be modified to achieve better results.