2022 Volume 104 Issue 1 Pages 1-9
About 7 hour's static observation with PPK analysis and 2.5 minute's RTK positioning per point were conducted at 10 points of outside forest and 21 points of inside forest to verify the accuracy of low-cost dual-frequency GNSS receivers. Average horizontal positional error of static observation with PPK analysis and RTK positioning under forest canopy were 1.22 and 1.72 m respectively and there was a significant difference, after excluding large positional error of more than 10 m. The horizontal positioning error of 4 satellite system (GPS + QZSS + GLONASS + Galileo) were less than the error of 3 satellite system (GPS + QZSS + Galileo) and the error of dual-frequency (L1 + L2) were less than the error of single-frequency (L1) for static observation with PPK analysis. Frequency of the large positional error occurrence got smaller as the elevation mask's value got bigger from 20 (25, 30) to 35 deg. The error of fix solution was less than float solution for RTK positioning. Average vertical positional error of static observation with PPK analysis and RTK positioning under forest canopy were 2.12 and 2.49 m respectively. It is suggested that horizontal position is decided by static observation with PPK analysis outside mobile phone network range, and by RTK positioning within mobile phone network first, then altitude value will be adopted from high resolution elevation model, which are developed recently.
