使用開源軟體RTKLIB探討GPS連續站地球科學應用案例

Discussion on the use of open-source software RTKLIB continuous GPS Earth Science Applications

范姜士彥(Shi-yan FAN-JIANG)

指導教授 ： 鄭凱謙

國立中正大學/理學院/地球與環境科學系應用地球物理與環境科學研究所/碩士(2016年)

摘要

GNSS 連續觀測陣列(array)是近年來在監測活動構造變形的有效工具之一。台灣現有的高密度 GNSS 連續觀測陣列，在地震發生後常被用來計算地震的同震位移，後續更可用來協助解算震源機制與地體動力模型反演等工作。在眾多GPS解算軟體中RTKLIB 為一款開源自由軟體，主要包括一般 GPS/GNSS 資料處理與基本的導航功能。軟體本身並非專為地球科學應用來開發，但具有圖形化介面、便於安裝、操作簡易等特色。與一般地球科學常用的專業軟體，例如 GAMIT/GLOBK(GG)、Bernese GPS有價格低廉、取得容易、操作簡單的優勢；與GIPSY 、CSRS-PPP線上軟體相比有可控參數多、批次處理、可以不用透過網路即可解算的優勢，此優勢尤其有利於教學的進行。本研究以三個主軸為研究內容，第一部份利用RTKLIB與GG解算美濃地震前後三天的GPS連續站資料來觀測同震位移的效果，結果顯是使用RTKLIB解算出各測站同震位移與GG的解各站相當吻合，並且使用RTKLIB解算高頻資料可以清楚的發現水平方向的同震現象；第二部份使用RTKLIB中的即時定位程式能夠有效監控野外的測站資訊，並且擁有航行記錄的功能，官方說法能夠在水平方向精度達到mm等級；第三部分選用了嘉南地區的三個GPS連續觀測站，以RTKLIB精密單點定位解算這三個測站在2013年的資料，並利用GG與兩款線上解算軟體(GIPSY、CSRS-PPP)加以驗證，使用GG當作真值來看，在結果上精密單點定位在解算速度場上還有待加強。

關鍵字

單基線差分定位 ； RTKLIB ； GPS連續觀測站 ； 精密單點定位 ； 即時連線

並列摘要

Continuous GPS array (array) is a structural deformation monitoring activities in recent years, one effective tool. Taiwan's existing high-density continuous GPS array, after the earthquake is often used to calculate earthquakes with seismic displacement, more follow-up can be used to assist in solving the focal mechanism and dynamic model inversion to body work. RTKLIB many GPS solver software as an open source free software, including general GPS / GNSS data processing and basic navigation functions. The software itself is not designed for earth science applications to develop, but with a graphical interface, easy to install, easy to operate, and other characteristics. Earth sciences and general common professional software, such GAMIT / GLOBK (GG), Bernese GPS have inexpensive, easy to obtain, simple operational advantages; and GIPSY, CSRS-PPP online software compared to more controllable parameters, batch processing , through the Internet can not be solver advantage, this advantage is particularly conducive to teaching. In this study, three spindle research, the use of the first part and GG RTKLIB solver Mino earthquake before and after the three-day continuous GPS data to observations with seismic displacement effect, the result was calculated using RTKLIB solution each station COSEISMIC GG Solutions displacement of the stations correlation coefficients above 0.8, goodness of fit is quite good, and the use of high-frequency data RTKLIB solver can clearly caught with horizontal seismic phenomenon; the second part of the real-time location using RTKLIB program can effectively monitor the station information field, and has a record of navigational functions, official statement can reach mm level accuracy in the horizontal direction; the third part selected three continuous GPS stations Chiayi area to RTKLIB precise point positioning Solutions Operators of these three test stand 2013 data, and the use of GG and two online solver software (GIPSY, CSRS-PPP) to be verified, as the use of GG true value point of view, RTKLIB the solutions of 2013 and the velocity field not ideal, it is the most consistent GIPSY followed CSRS-PPP.

This study shows that during the short period of time RTKLIB single baseline solution with high-frequency seismic displacement and seismic observation data signal count solution, the performance is quite good, and the software itself is open source, free of charge, under the operating conditions can facilitate in the real-time location achieve experiment mm level, but for a long time velocity field estimate the magnitude of the change in the daily solution is too large, and there is a half anniversary of the noise not eliminated, in this experiment did not do the filtering process, leading the whole velocity field in the wrong direction.

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