Comparison of GPS receiver accuracy and precision in forest environments, practical recommendations regarding methods and receiver selection
Rodriguez-Perez, Jose R. ... [et al]
Selecting the appropriate receiver and methods might be complicated when a major portion of GPS data collection is below forest canopies. This study compares recreational GPS receivers (GARMIN eTrex Euro, GARMIN 12XL, GARMIN Summit, GARMIN Geko 201) and more precise GPS receivers (Topcon Hiper+). It was aimed to determine the most suitable method and receiver for position assessment under different forest canopy covers, in terms of easiness of use, accuracy, reliability, and the ratio accuracy/cost. Data were collected in 17 forest locations and consisted of 3 measurements with each receiver per plot and positioning method. Each plot was visited 11 times; therefore there were 33 measurements per receiver, plot and method. Several positioning techniques were compared: autonomous, real-time differential, and post-processed differential modes, as well as the effect of using an augmentation system. Data were described and analyzed through a sample comparison analysis at 95% confidence level (Dunnet test for normal data, and Mann-Whitney test for data which do not fit a normal distribution), in order to validate the following null hypothesis: (i) all receivers have the same accuracy and precision at measuring horizontal coordinates, (ii) all receivers have the same accuracy and precision determining altitudes, (iii) accuracy and precision do not depend on characteristics of forest canopy, and (iv) differences in accuracy and precision between receivers are independent of forest canopy characteristics. Results showed that there were significant differences between the receivers regarding accuracy and precision measuring coordinates; moreover, accuracies were different depending on the canopy cover and forest characteristics. Therefore, practical recommendations for each case were settled in order to help foresters to select the most suitable receiver.
Event: XXIII International FIG Congress : Shaping the change
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