Evaluation of Positioning Accuracy of Smartphones under Different Canopy Openness

This study focuses on evaluating the positioning accuracy of smartphones in a deciduous forest environment compared to various levels of Global Navigation Satellite System (GNSS) devices. In a mixed coniferous forest with 90% broad-leaved forest (deciduous season), the accuracy of 57 test points was evaluated according to different openness levels under the forest. Taking the coordinates obtained by survey-grade GNSS devices in RTK (Real-time Kinematic) mode as standard, the accuracy of the single-point positioning (SPP) mode and precise-point positioning (PPP) mode obtained by three smartphones (one single frequency and two dual frequency), one survey-grade receiver and one recreational-grade receiver are compared. It can be found that there was a significant positive correlation between canopy openness and carrier-to-noise density(C/N0) (p 0.7). However, in an environment with low openness (R < 0.7) and relatively complex forest area positioning, survey-grade GNSS devices are still required to cooperate with the PPP or real-time differential positioning method to obtain accurate sub-meter-level positioning data