A study of the effects of stems and canopies on the signal to noise ratio of GPS signals

This study investigated the relationship between the quantity of the shielding effect by wood material and the lowering of the signal to noise ratio (SNR) of global positioning system (GPS), signals. Three types of wood materials, namely, Japanese cedar board (JCB), Japanese cedar needle (JCN), and deciduous broadleaf (DBL), were prepared. We performed analysis by quantification I to clarify the factors that affect SNR. Approximately 60% of SNR could be explained by wood resistance quantity (Wrq) and satellite elevation angle SEA. The order of the factors that effect SNR was SEA > Wrq > experimental date > type of wood material > permeation distance through wood material (Dwm). We could formulate the relationship between Wrq and SNR. The Monte Carlo simulation was used to confirm the relationship between SNR and Wrq. The results of the positioning fix ratio by the simulation showed an excessive value in the coniferous forest that almost corresponded with that of the deciduous broad-leaved forest.