由未差分的GPS相位資料推求接收儀時錶誤差之研究

Study on Processing Undifferenced GPS Phase Data to Calculate GPS Receiver's Clock Errors

目前由工業技術研究院量測技術發展中心代管的國家度量衡標準實驗室，已完成建置GPS定位校正網，應用高準確度校正網，並追溯連繫至國際IGS固定站ITRF坐標系，依校正程序對GPS接收儀進行評估應是有效方法之一；除了利用坐標比對進行追溯之外，以頻率傳遞的GPS追溯鏈應也是可行的追溯方法。本文即利用未差分的GPS相位資料推求接收儀時錶誤差，採用瑞士伯恩大學天文研究所研發的Bernese4.2軟體，對於四種廠牌六種型式的GPS接收儀進行內部時間偏移量及頻率穩定度的評估。結果顯示，使用相位推求接收儀內部時鐘偏移量，以D型的時間偏移量最小，而以E型的時間偏移量最大；而使用相位推求接收儀內部頻率穩定度，以B型的頻率穩定度最佳，而以E型的頻率穩定度最差，但其差異量並不會很明顯。其評估的結果除了可對各種型式的GPS接收儀內部時錶穩定度進行分析之外，後續並可作為GPS定位校正的參考依據，進而探討藉由頻率傳遞的GPS追溯鏈。 The GPS receiver calibration network has already been established by National Measurement Laboratory which is maintained by Center for Measurement Standards Standards, Industrial Technology Research Institute. Using the high accuracy GPS receiver calibration network which is tied to the ITRF coordinates of the IGS stations will be an effective method for evaluating the performance of the GPS receivers. Besides, it will be an operable method to transfer standards via frequency. In this study, the internal clock errors of GPS receivers have been calculated using undifferenced GPS phase data and six kinds of GPS receivers' clock offset and frequency stability have been estimated using Bernese version 4.2 software. In the results, the clock offset of type D is smallest and the clock offset of type E is largest. The frequency stability of type B is best and the frequency stability of type E is worst. We can use the results to analysis every kinds of GPS receivers' clock errors. Furthermore, GPS traceability chart can be discussed and as the reference standards of calibrating GPS receivers.

The GPS receiver calibration network has already been established by National Measurement Laboratory which is maintained by Center for Measurement Standards Standards, Industrial Technology Research Institute. Using the high accuracy GPS receiver calibration network which is tied to the ITRF coordinates of the IGS stations will be an effective method for evaluating the performance of the GPS receivers. Besides, it will be an operable method to transfer standards via frequency. In this study, the internal clock errors of GPS receivers have been calculated using undifferenced GPS phase data and six kinds of GPS receivers' clock offset and frequency stability have been estimated using Bernese version 4.2 software. In the results, the clock offset of type D is smallest and the clock offset of type E is largest. The frequency stability of type B is best and the frequency stability of type E is worst. We can use the results to analysis every kinds of GPS receivers' clock errors. Furthermore, GPS traceability chart can be discussed and as the reference standards of calibrating GPS receivers.