Evaluation of GPS positioning accuracy while walking in forested areas.

摘要

In this study, we measured the positioning accuracy of the global positioning system (GPS) while walking in forested areas and analysed the GPS data to find factors that affect the positioning accuracy. In the field tests, we repeated GPS measurements with different types of GPS receivers, types of forests and modes of GPS positioning. The GPS data were analysed using ANOVA. As a result, the type of GPS receivers, type of forests and modes of GPS positioning were found to be a significant factor (p<0.001) to determine positioning accuracy while any interactions between these factors were not. The result also showed that the GPS receiver with multipath rejection technology produced higher positioning accuracy than without it. Therefore, multipath errors, which are caused by the reflection of GPS signals due to nearby stems, can be a critical cause to adversely affect GPS positioning accuracy. It was also suggested that GPS positioning accuracy while walking in forested areas was affected not by basal area but by stand density. That was because temporal signal blocking occurred more often with increasing stand density while walking forested areas. As a result of multiple regression analysis, the observed position dilution of precision was not a significant factor (p=0.590) to determine positioning accuracy.