Development of the forest monitoring method using GPS signal degradation under tree canopies

本研究的目的是建立一种利用SIP （Signal Interruption Probability，信号中断概率）值来估计GPS定位精度和林分体积或林分密度等林分信息的方法，SIP值表示GPS信号接收状态除以森林冠层。不同林分和季节的GPS观测试验表明，10 ~ 15 min SIP值与GPS定位误差的相关性最高，且SIP值与GPS定位误差的相关性显著高于半球面照片计算的冠层开度指数和DOP值。此外，还澄清了SIP不仅可用于GPS定位，还可用于GPS和GLONASS的组合使用，并且SIP可用于通过使用GPS和GLONASS接收器进行的GNSS观测测试认为难以实现的浮子解决方案的误差管理。

Objective of this study is to establish a method for estimation of GPS positioning accuracy and stand information, such as stand volume or stand density, by using SIP (Signal Interruption Probability) value, which indicates status of GPS signal reception divided by forest canopies.It was clarified that SIP values calculated from 10 - 15 minutes have the highest correlation to GPS positional errors, and the correlation of SIP values to GPS positional errors is significantly higher than the canopy opening index calculated by a hemispherical photograph and DOP value through GPS observation tests in various forest stands and seasons.Furthermore, it was also clarified that SIP can be applied to not only GPS positioning but also combination use of GPS and GLONASS, and that SIP can be used for error management for float solutions which is considered to be difficult through GNSS observation tests using GPS and GLONASS receivers.