Positioning accuracy analysis of RBN DGPS applied in precision forestry

To examine the applicability of GPS and Radio Beacon Differential Global Positioning System (RBN DGPS) for forestry machinery positioning, experiments were conducted using the non-differential and RBN DGPS mode -of a Trimble AgGPS132. Coordinate change process figures and scatter distribution figures were used to compare the accuracy of the different position modes. Average values and standard deviation were also used to analyze the precision. The stationary test (where the mobile platform was maintained at a fixed location) was carried out to investigate the static conformity degree. The mobile test (where the platform was moving along certain path of circle) was conducted to examine the dynamic conformity degree accuracy of GPS signals. The results showed that the RBN DGPS mode improved the accuracy of x and y axis by 12%-47% than non-differential mode. In the stationary test, the variability of x and y coordinates was much smaller in RBN DGPS than that in the non-differential mode. In the mobile test, the traces of the moveable platform (circles) were much better represented with the locations recorded in the RBN DGPS mode. It was found that RBN DGPS was more suitable than non-differential mode for precision forestry positioning requirements. In regions where beacon DGPS signal coverage in China is available, RBN DGPS has enormous potential for application of precision forestry due to its continuous signals, reliability, high accuracy and low cost.