American Society of Civil Engineers

Assessment of Low-Cost GPS Receiver Accuracy and Precision in Forest Environments

by José R. Rodríguez-Pérez, (corresponding author), (Asst. Prof., Univ. of León, ESTIA, Avda. Astorga s/n., 24400 Ponferrada, León, Spain E-mail:, M. F. Álvarez, (Asst. Prof., Univ. of León, ESTIM, Avda. Astorga s/n., 24400 Ponferrada, León, Spain. E-mail:, and Enoc Sanz-Ablanedo, (Asst., Univ. of León, ESTIA, Avda. Astorga s/n., 24400 Ponferrada, León, Spain. E-mail:

Journal of Surveying Engineering, Vol. 133, No. 4, November 2007, pp. 159-167, (doi:

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Document type: Journal Paper
Abstract: Selecting the appropriate receiver is an issue when a major portion of global positioning system (GPS) data collection is below forest canopies. This study compares four low-cost GPS receivers, in order to determine the most suitable receiver for position assessment under different forest canopy covers, in terms of ease of use, accuracy, and reliability. A total of 33 positional assessments were gathered per receiver, plot, and method, in 18 forest locations. Data were described and analyzed through a sample comparison analysis at 95% confidence level (Mann — Whitney nonparametric test), in order to determine the existence of differences in accuracy and precision in positioning between receivers. 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. Moreover, key forest variables regarding GPS performance were identified, so that forest environments could be effectively clustered by them.

ASCE Subject Headings:
Geomatic surveys
Global positioning systems