Reliability of GNSS satellite horizontal positioning in forest environment by handheld GPS receivers

Abstract

Reliability of GNSS satellite horizontal positioning in forest environment by handheld GPS receivers The present research refers about accuracy and precision determination by handheld GPS receivers used for planimetric surveys in forest environments. The position-fixes have been recorded at 1 second frequency and then averaged for different time ranges. In this way it has been possible to simulate increasing acquisition ranges in order to evaluate the effects on accuracy and precision parameters. The test area is located on the slopes of a mountain in the Apennine mountain range considered representative of morphologic and vegetational conditions of the basal zone. For this work, the Authors have referred to some parameters usually indicated by producing companies and to the Guidelines for Digital Map Base Updates of Cartographic Specifications and Symbols (EM-7140-24). The results about accuracy and precision have shown a considerable influence of the number of fixes for each point position and of the canopy cover, even without leaves. The examined parameters have sensibly improved when the positioning ranges increase from 1 second to 5 minutes.