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題 名 | 利用GPS觀測量構建即時的區域電離層模型之研究=A Study on Real-Time Regional Ionosphere Modeling Using GPS Measurements |
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作 者 | 林老生; | 書刊名 | 測量工程 |
卷 期 | 41:1 1999.03[民88.03] |
頁 次 | 頁5-31 |
分類號 | 440.98 |
關鍵詞 | Global positioning system; Ionospheric delay; Total electron content; Thin-shell model; Ionospheric pierce point; Grid-Based algorithm; 全球定位系統; 電離層延遲; 全電子含量; 薄殼模型; 電離層穿透點; 網格式演算法; |
語 文 | 中文(Chinese) |
中文摘要 | 在精密全球定位系統(GPS)定位及導航應用方面,電離層延遲為GPS觀測量的主 要誤差來源之一。電離層延遲的大小,與從GPS人造衛星至接收機電磁波路徑沿線之全電子 含量(Total Electron Content, TEC)有密切關係。而TEC的變化量又跟很多變數有關,例 如,太陽黑子的數目、磁場的活動狀況、觀測的季節、觀測的時間、觀測的地點及方向等。 由雙頻GPS接收機的觀測量,經過處理後,可以估計當時的TEC。因此,利用此特性,可以 將多部的雙頻GPS接收機佈設在一特定區域,即時的估計電離層延遲,並構建區域性的電離 層模型,提供單頻GPS接收機使用,以消除電離層延遲,提高單頻GPS接收機導航、定位之 精度。 網格式演算法,為構建即時的區域電離層模型的方法之一,通常以簡單的權函數來控制 參考點的比重,並用廣播星曆中之電離層模型來計算網格點與參考點間之電離層延遲比。為 了提高即時的區域電離層模型精度,本文提出提出一種改良式的演算法,其與傳統的網格式 演算法不同的地方有二:(1)以特殊的指數函數取代簡單的權函數,及(2)以前一天的GPS資 料所構建之區域電離層模型,取代廣播星曆中之電離層模型。由美國、日本及澳洲等不同地 區的GPS觀測網站資料,將被用以測試本文所提之方法。由實驗結果證明,利用本文提出的 改良的網格式演算法,可以有效的提高即時的區域電離層模型之精度。 |
英文摘要 | The ionospheric delay is one of the main sources of error in precise GPS positioning and navigation. The magnitude of the ionospheric delay is related to the Total Electron Content (TEC) along the radio wave path from a GPS satellite to the ground receiver. The TEC is a function of many variables, including long and short term changes in solar ionising flux, magnetic activity, season of the year, time of day, user location and viewing direction. A dual-frequency GPS receiver can eliminate (to the first order) the ionospheric delay through a linear combination of L1 and L2 observables. However, the majority of civilians use low-cost single-frequency GPS receivers that cannot use this option. Consequently, it is beneficial to estimate ionospheric delays over the region of interest, in real-time, in support of single-frequency GPS positioning and navigation applications. One real-time regional ionosphere modelling method is grid-based algorithm. Usually, a simple weighting function, such as inverse distance, is adopted as the weighting criteria for the reference points, and the Klobuchar model is used to predict the ionospheric delay ratios between the grid points and reference points. In order to improve real-time regional ionosphere modelling performance, an alternative grid-based algorithm is proposed. In this new algorithm, an exponential function is adopted as the weighting function and the grid-based ionosphere model estimated from previous day is used to predict the ionospheric delay ratios between the grid point and reference points. Data from the Australian Regional GPS Network (ARGN), Permanent GPS Geodetic Array (PGGA), USA, and Japan Geographical Survey Institute (GSI) GPS network were used to test the ionosphere modelling algorithms. From the test results described here, it is shown that the performance of real-time regional ionosphere modelling is improved significantly when the proposed algorithm is used. |
本系統中英文摘要資訊取自各篇刊載內容。