Abstract:In view of the need to achieve high-precision positioning and navigation in forest resources investigation and monitoring, taking the experimental area with cork ridge as main tree species in the Jiufeng National Forest Park, and the Sanding T-23 multi-frequency Samsung receiver and u-blox NEO-M8T multi-receiving modules to carry out a four-hour positioning observation on the observation points in the forest, and the forest BDS/GPS combined positioning algorithm was established by using BDS and GPS observation data through unifying time and space between systems as well as reasonable observation weights. Afterwards, the algorithm was put into the RTKLIB software to realize three-dimensional coordinate calculation of forest observation points (WGS-84 coordinate system), and finally the results were compared and analyzed with single GPS positioning results. The experimental results showed that the visible digits of forest BDS/GPS combined positioning satellites was 15~23, which was much higher than the visible digits of single GPS positioning satellites (the number was 11). The BDS/GPS combined positioning PDOP value was between 0.5 and 1.8, which was lower than that of the single GPS positioning PDOP value, but the changing trend was relatively similar. The SNR values of BDS/GPS combined positioning and GPS positioning satellite were both 10~50dB. However, due to the more visible digits of BDS/GPS combined positioning satellites, the satellite signal was stronger and the SNR value was more stable. The theoretical accuracy of the BDS/GPS combined positioning results in the X, Y and Zdirections respectively were 2.603m, 3.302m and 3.125m, and the theoretical accuracy of the single GPS positioning results in the X, Y andZ directions were 2.382m, 4.669m and 4.344m. The actual accuracy of BDS/GPS combined positioning results in X, Y and Z directions were 3.112m, 3.542m and 4.073m, and in terms of the single GPS positioning result, it turned out to be 4.946m, 5.254m and 7.274m.
