Validating VRS-based Post-processing Kinematics GPS for Horizontal Densified Surveying

A virtual station-based post-processing kinematic (VRS-PPK) positioning technique is advantageous for operations that do not require users to establish a base station or employ a real-time communication device. Through a VRS system, this technique is potentially applicable for horizontal densified surveying. This study adopted the static observation data obtained through the control station resurvey in 2012 (conducted by the Taiwan Ministry of the Interior) to examine the internal precision and external accuracy of VRS-PPK positioning, thereby providing application standards for using this technique to conduct horizontal densified surveying or other types of surveying. The results revealed that after the testing sites were screened through the criterion that the standard deviation of each observation set must be less than 2 cm in horizontal component and less than 5 cm in height component, the success rate of testing site positioning was determined to be 70%. The morning session attained the highest success rate, and the average standard deviation of the plane coordinates was 1.3 cm. Next, the difference between the two observation sets of each testing site coordinate was examined. The results revealed that 92% of the testing sites attained a set difference not exceeding 2 cm in either N or E component. However, when the tolerance for set difference was increased to 3 cm, 97% of the testing sites could meet the set difference standard. Subsequently, the baseline length differences between the VRS-PPK and static solutions were examined. The results indicate that the specification for examining baseline length differences can be tightened up to 20 mm + 4 ppm × L, which can serve as a standard for control station resurvey using VRS-PPK.

關鍵字

VRS ； RTK ； PPK ； Horizontal Densified Surveying

並列摘要

VBS-PPK定位解算技術具有不須自行設置基站，也不須配置即時通訊裝置之條件，在配合VBS系統之運作下，具有進行平面加密測量之潛在優勢。本研究利用2012年内政部辦理基本控制點檢測工作之靜態觀測資料，配合觀測數據所產製之VBS觀測量，進行VBS-PPK定位成果之内、外部精度（interior and external precision）檢視，以提供該技術辦理平面加密測量或辦理檢測之適用標準。由研究成果可知，採用平面2 cm及高程5 cm進行測回（set）中誤差（standard deviation）之初步篩選後，觀測組之定位解算成功率僅達70%，且以上午時段之成功率為最佳，整體資料之平面坐標中誤差為1.3cm。再針對二組測回平均坐標（coordinate）求取較差（set difference）時，任一平面分量（horizontal component）超出2 cm標準之點位數量可達8%，若可放寬至較差小於3 cm時，測點之通過率將可達到97%。通過中誤差及測回較差檢核之VBS-PPK定位成果，在組成基線（baseline）進行其標準長度之差異檢核時，其成果反映之檢核標準可較參考規範（specification）拉高至20 mm＋4 ppm×L，以作為VBS-PPK辦理平面控制點檢測（re-survey）標準使用。

並列關鍵字

虛擬基準站；即時動態定位；後處理動態定位；平面加密測量

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