英文摘要 |
Deploying a "simple monitoring station" is the current practice for monitoring the large-scale potential landslide sites in Taiwan. Due to financial considerations, single frequency GNSS receivers are utilized. This study takes the D015 site, located in Liugui, Kaohsiung city, as a sample to understand the performance of these GNSS stations. From previous studies, the data collected from these stations in 2017 have confirmed that there are many problems resulting from both implementation and environmental factors. Frequent data error and data voids were found. Some of these could be resolved with data processing, but not the problems from point determination geometry. While processed with Canadian CSRS-PPP services, the uncertainty presented as the square root of sum of the three dimensional estimated coordinate variances all larger than 1 m, for all six GNSS stations in D015. The data period covered was the month of October, 2017. Because the "differential network adjustment" method could produce better results when the baseline is short, this study evaluated the same dataset with this method. Daily static solutions were derived. Although not many day observations could be processed successfully, only about 10%, the result shows that the best results have uncertainty of 0.054 m and the worst uncertainty of 1.013 m, after two gross errors were removed. It may be concluded that short baseline network of single frequency receivers could reach cm level positioning with "differential network adjustment". However, from the data of the study period from D015, the factors including environmental prevented this from being realized. |