單頻差分網形平差與精密單點定位比較：六龜D015大規模崩塌潛勢區簡易觀測站案例

Comparing the Differential Network Adjustment with PPP for Kaohsiung Liugui D015 Monitoring Stations Single Frequency GNSS Data

史天元 ； 王慧蓉 ； 廖志中

《地籍測量：中華民國地籍測量學會會刊》 38卷4期 (2019/12) Pp. 1-9

摘要

設置「簡易觀測站」，是目前針對「大規模崩塌潛勢區」進行監測與探討的具體作為。基於經費的考量，單頻GNSS接收儀為普遍採用的設備。本研究以高雄市六龜區D015為探討案例，以了解多年來所設置「簡易觀測站」之GNSS數據解算狀況。由前期研究成果，業已獲得明確結論，由於種種環境與實際作業之綜合影響，2017年度GNSS接收之狀況不佳，數據缺漏、包含大量數據錯誤、等狀況十分頻繁。其中檔案中包含錯誤等問題，可以藉由增加作業工序方式排除。但是基本幾何圖形的限制，則非任何後處理可以解決。在以加拿大CSRS-PPP精密單點定位網際服務分析時，D015區域六個GNSS觀測站於2017年10月所蒐集之數據，即便是單日靜態解，所呈現之成果，各站三向坐標平方和之根，均大於1m。由於在基線短時，電離層等環境影響因素在小區域中各站較接近，可以藉由差分獲得較好成果，本文即以「差分網形平差」進行D015的解算。成果顯示，平差後以誤差傳播估計之坐標不確定度，三向坐標平方和之根，在扣除兩筆粗差之後，最小約0.054 m，最大1.013 m。根據計算成果，本研究推論，單頻GNSS接收儀在短基線時，「差分網形平差」有潛力可以獲得釐米級精度。但是在研究期間D015區域所設置者，由於諸多因素如環境影響，大多數未能達成此標準。

並列摘要

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.