Analysis of the accuracy of GPS Trimble JUNO ST measurement in the conditions of forest canopy

Abstract

GPS Trimble JUNO ST was tested at 16 points under forest canopy. The measurements were done on three different dates of the growing seasons in 2007 and 2008. On each date, 4 recordings were measured in the length of 1,2,5, and 10 minutes with the recording frequency of 5 seconds. The resultant data were statistically evaluated by analysis of variance (ANOVA) both for data before corrections and for data after post-process corrections from the reference station. The tested GPS receiver reaches the average mean square error of the measurement of XY coordinates in the interval of 2.7 up to 5.1 m (without corrections and depending on the time of observation). The error of the altitudinal (Z) coordinate measurement is three times the average MSE XY. The use of corrections from reference stations turns out to be ineffective. No statistically significant relationship was proved between the PDOP value and the error of measurement of the position or height, and there was no significant relationship of the type of stand or stand density or the type of relief. By contrast, the age of stand was statistically significant and there are higher MSE XY values in older stands, depending, however, on the stand density.