1、精選優(yōu)質(zhì)文檔-傾情為你奉上專心-專注-專業(yè)中文翻譯中文翻譯基于基于 GPSGPS 數(shù)據(jù)的電離層模型和電離層延遲改正新方法研究數(shù)據(jù)的電離層模型和電離層延遲改正新方法研究摘要根據(jù)當(dāng)前大地測(cè)量、地球物理、空間物理和導(dǎo)航等領(lǐng)域的科學(xué)研究和工程應(yīng)用中的若干重要 GPS 科研項(xiàng)目的需要，近年來，我們系統(tǒng)研究了電離層延遲的高精度模擬和改正方法。本文報(bào)告的內(nèi)容，是我們研究工作的部分貢獻(xiàn)，主要涉及基于 GPS 的電離層監(jiān)測(cè)及延遲的高精度改正的理論與方法的研究：如何通過修正靜、動(dòng)態(tài)單、雙頻用戶的電離層延遲影響，進(jìn)一步改善 GPS 測(cè)量的精度和可靠性；增強(qiáng)型 GPS 廣域差分系統(tǒng)的電離層模擬及利用 GPS 監(jiān)測(cè)電離

2、層的理論和方法等方面關(guān)鍵詞：GPS 的電離層監(jiān)測(cè)，電離層延遲，GPS 廣域差分本文主要包括兩方面的內(nèi)容：本文主要包括兩方面的內(nèi)容：一、研究背景的一般性描述及相關(guān)基礎(chǔ)研究的系統(tǒng)總結(jié)和介紹一、研究背景的一般性描述及相關(guān)基礎(chǔ)研究的系統(tǒng)總結(jié)和介紹, ,主要涉及：主要涉及：地球電離層研究意義, 地球電離層探測(cè)技術(shù)與相關(guān)理論研究的內(nèi)容,現(xiàn)代大地測(cè)量中電離層問題的由來、嚴(yán)重性與新課題, 地球電離層的基本特性及其對(duì)電波傳播的影響，GPS 定位的基本理論與方法，電離層延遲對(duì) GPS 測(cè)量的影響，GPS的電離層延遲改正的基本方法，基于 GPS 的電離層研究的基本原理與方法等。進(jìn)而論述了解決 GPS 的電離層延遲影

3、響的重要性和切入點(diǎn)。二、具體研究工作的系統(tǒng)報(bào)告，主要集中在以下幾方面二、具體研究工作的系統(tǒng)報(bào)告，主要集中在以下幾方面: : 研究如何利用單臺(tái)雙頻 GPS 接收機(jī)的觀測(cè)信息確定電離層延遲改正模型，為小范圍的單頻用戶服務(wù)；研究如何實(shí)時(shí)分離 GPS 觀測(cè)中的儀器偏差與電離層延遲；研究如何建立較大區(qū)域的電離層格網(wǎng)模型，進(jìn)而初步設(shè)想利用中國地殼運(yùn)動(dòng)觀測(cè)網(wǎng)絡(luò)深入研究我國領(lǐng)域的電離層的電子濃度變化規(guī)律；研究單頻用戶在不利條件下，如何更好地利用電離層延遲改正信息；研究利用 GPS 監(jiān)測(cè)隨機(jī)電離層擾動(dòng)的基本理論和框架方案；研究如何綜合顧及電離層的周日、季節(jié)和年變化，進(jìn)一步提高利用 GPS模擬電離層延遲的能力；研

4、究如何實(shí)現(xiàn)星載單頻 GPS 低軌衛(wèi)星的精密測(cè)軌中的電離層延遲改正要求。1.1. ( (局部局部) )電離層延遲的高精度提取電離層延遲的高精度提取精選優(yōu)質(zhì)文檔-傾情為你奉上專心-專注-專業(yè)系統(tǒng)論述和分析了影響利用 GPS 觀測(cè)精確提取電離層延遲信息的各類因素。通過對(duì)有關(guān)模型和方法問題的深入研究，進(jìn)一步提高了利用 GPS 提取電離層延遲信息的精度。主要包括：（1）將參數(shù)固定的三角級(jí)數(shù)函數(shù)電離層模型，擴(kuò)展為更適用于理論研究和實(shí)際應(yīng)用的參數(shù)可調(diào)型廣義形式，實(shí)現(xiàn)了根據(jù)電離層延遲時(shí)空變化特征，選擇不同的特征參數(shù)模擬電離層延遲的影響。試算結(jié)果表明，它能較好地反映電離層活動(dòng)特性，提高了局部電離層延遲模擬能力，

5、適用于 DGPS 系統(tǒng)修正其服務(wù)區(qū)域內(nèi)的單頻 GPS 用戶的電離層延遲。（2）設(shè)計(jì)了幾種不同的計(jì)算方案，用于分析儀器偏差對(duì)確定電離層延遲的影響的特點(diǎn)。研究表明，儀器偏差對(duì)求解電離層延遲的影響遠(yuǎn)大于觀測(cè)噪聲的影響，給電離層延遲觀測(cè)值帶來高達(dá)數(shù)米的系統(tǒng)誤差。利用 GPS 觀測(cè)數(shù)據(jù)求解電離層模型或直接計(jì)算斜距電離層延遲時(shí)，都須慎重處理儀器偏差，不應(yīng)簡(jiǎn)單把其作為噪聲處理;（3）利用相位平滑測(cè)碼數(shù)據(jù)進(jìn)一步精化了儀器偏差分離方法，探討了儀器偏差的穩(wěn)定性。研究發(fā)現(xiàn)，新方法可有效克服噪聲對(duì)分離儀器偏差的影響，而且儀器偏差相對(duì)穩(wěn)定并可有效進(jìn)行測(cè)段間及數(shù)日間預(yù)報(bào)。（4）基于實(shí)時(shí)平均去噪和碼、相位觀測(cè)數(shù)據(jù)的加權(quán)聯(lián)合

6、處理的思想，提出了一種實(shí)時(shí)分離儀器偏差和求解電離層延遲量的新方案。算例表明，新方法通過采用平均去噪分離方法后處理相位平滑測(cè)碼數(shù)據(jù)，求出儀器偏差并對(duì)需要實(shí)時(shí)處理儀器偏差的觀測(cè)數(shù)據(jù)進(jìn)行預(yù)報(bào)改正，直接利用觀測(cè)值確定電離層延遲量，待估參數(shù)少、能消除儀器偏差的大部分影響，具有較好的精度，可作為 WAAS 及其他 GPS 網(wǎng)絡(luò)系統(tǒng)確定電離層延遲的可行的參考方案。2.2. 一種構(gòu)建大規(guī)模一種構(gòu)建大規(guī)模( (區(qū)域性和全球性區(qū)域性和全球性) )高精度格網(wǎng)電離層模型的新方法高精度格網(wǎng)電離層模型的新方法站際分區(qū)法及其在中國的初步實(shí)現(xiàn)站際分區(qū)法及其在中國的初步實(shí)現(xiàn)在系統(tǒng)深入研究了格網(wǎng)電離層模型建立原理與方法的基礎(chǔ)上，

7、為避免基準(zhǔn)站網(wǎng)的幾何結(jié)構(gòu)對(duì)模型精度估計(jì)的影響，充分顧及電離層延遲影響的局部特性，進(jìn)一步提高格網(wǎng)電離層模型的構(gòu)建精度，提出了一種新的格網(wǎng)電離層模型構(gòu)建方法站際分區(qū)格網(wǎng)法。在以上研究的的基礎(chǔ)上，估計(jì)了利用地殼運(yùn)動(dòng)觀測(cè)網(wǎng)絡(luò)的基準(zhǔn)網(wǎng)建立格網(wǎng)電離層模型的精度，初步探討中國域內(nèi)擬建立的廣域差分 GPS 增強(qiáng)系統(tǒng)，采用格網(wǎng)電離層模型提供電離層改正信息的可行性及有待進(jìn)一步研究的問題。3.3. 不利條件下為不利條件下為 WAASWAAS 的單頻的單頻 GPSGPS 用戶提供電離層延遲改正用戶提供電離層延遲改正的新方法的新方法APR-IAPR-I 方案方案在正常條件和平靜電離層區(qū)域，WAAS 能夠滿足單頻用戶的電

8、離層延遲改正精選優(yōu)質(zhì)文檔-傾情為你奉上專心-專注-專業(yè)要求，但當(dāng)用戶無法正常獲取電離層延遲改正信息時(shí)，如在差分系統(tǒng)突然中斷信息發(fā)送或用戶步入無法正常接收差分改正信息的位置等不利條件下，單頻GPS 接收機(jī)不能有效進(jìn)行實(shí)時(shí)電離層延遲改正，尤其在電離層活動(dòng)異常區(qū)域如電離層擾動(dòng)條件下，實(shí)時(shí)差分改正效果將受到嚴(yán)重影響。這些問題在 WAAS 的實(shí)際運(yùn)行中是難以避免和必須解決的。而以往的研究結(jié)果，均為后處理方法，不能滿足(準(zhǔn))實(shí)時(shí)處理電離層擾動(dòng)的要求。針對(duì)這種狀況，我們通過設(shè)計(jì)能有效結(jié)合電離層延遲絕對(duì)量和相對(duì)變化量的抗差遞推過程，提出了一種可在以上不利條件下有效實(shí)時(shí)改正單頻 GPS 用戶電離層延遲的方法AP

9、R-I 方案。1）構(gòu)建 APR-I 方案的理論依據(jù)WAAS 正常運(yùn)轉(zhuǎn)和正常條件下可提供高精度的電離層延遲改正信息(絕對(duì)量)，而 WAAS 所服務(wù)區(qū)域內(nèi)的單頻 GPS 接收機(jī)在不利條件下也能有效提供電離層延遲變化量(相對(duì)量)，且在不考慮噪聲影響，可直接計(jì)算任意兩觀測(cè)歷元間的電離層變化量的近似值。2）提出 APR-I 方案通過設(shè)計(jì)能有效結(jié)合電離層延遲絕對(duì)量和相對(duì)變化量的抗差遞推過程，研究了一種新的單頻 GPS 電離層延遲改正方案(稱為 APR 方案,即 Absolute Plus Relative Scheme)；給出了 APR-I 方案的精度估計(jì)公式；分析實(shí)施 APR-I 方案的有效途徑。研究表

10、明，新方案既保留正常條件下差分電離層延遲信息的精確改正效果，也確保了在不利條件下單頻 GPS 用戶的電離層延遲改正效果。APR-I 方案的實(shí)施，不需改變 WAAS 原有的整體設(shè)計(jì)思想，對(duì)硬件無新的要求，只需對(duì)用戶 GPS軟件稍加改進(jìn)，實(shí)施簡(jiǎn)便，是 WAAS 和單頻 GPS 用戶均可接受和易于實(shí)現(xiàn)的。4.4. 檢測(cè)隨機(jī)信號(hào)的新理論檢測(cè)隨機(jī)信號(hào)的新理論變樣本自協(xié)方差估計(jì)的提出變樣本自協(xié)方差估計(jì)的提出及其在及其在 GPSGPS 監(jiān)測(cè)隨機(jī)電離層擾動(dòng)中的應(yīng)用監(jiān)測(cè)隨機(jī)電離層擾動(dòng)中的應(yīng)用根據(jù) GPS 時(shí)序觀測(cè)的特點(diǎn)，通過設(shè)計(jì)先研究樣本時(shí)序變化時(shí)隨機(jī)電離層折射的自協(xié)方差估計(jì)的統(tǒng)計(jì)特性，再探討利用 GPS 實(shí)時(shí)

11、監(jiān)測(cè)電離層活動(dòng)的新方法的思路，從基礎(chǔ)理論的提出到框架方案的建立，系統(tǒng)深入研究了利用 GPS 監(jiān)測(cè)隨機(jī)電離層擾動(dòng)的基本理論與方法。具體包括：1）研究變樣本自協(xié)方差估計(jì)(ACEVS)理論從一般的數(shù)學(xué)意義上建立了 ACEVS 的基本模型，并在進(jìn)一步擴(kuò)展白噪聲理論的基礎(chǔ)上，得到了 ACEVS 估計(jì)的理論和簡(jiǎn)化解式，即變樣本自協(xié)方差估計(jì)的統(tǒng)計(jì)模型參數(shù)估計(jì)解式，進(jìn)而建立了隨機(jī)信號(hào)擾動(dòng)的診斷準(zhǔn)則。2）ACEVS 估計(jì)應(yīng)用于 GPS 電離層監(jiān)測(cè)的可行性的理論證明與模擬分析精選優(yōu)質(zhì)文檔-傾情為你奉上專心-專注-專業(yè)不僅從理論上證明了 ACEVS 應(yīng)用于 GPS 電離層監(jiān)測(cè)的可行性，而且利用雙頻 GPS 數(shù)據(jù)也成

12、功地模擬了隨機(jī)電離層折射的 ACEVS 估計(jì)的特性，并發(fā)現(xiàn)，變樣本自協(xié)方差估計(jì)的統(tǒng)計(jì)特性對(duì)隨機(jī)電離層延遲變化是敏感的；初步討論和分析了 GPS 觀測(cè)提供的 TEC 變化也適用于 ACEVS 方法應(yīng)用條件.3）建立利用 GPS 監(jiān)測(cè)隨機(jī)電離層擾動(dòng)的框架方案綜合 ACEVS 理論及相關(guān)的結(jié)論和 GPS 時(shí)序采樣的特點(diǎn)，初步給出一種基于GPS 的電離層擾動(dòng)監(jiān)測(cè)的框架方案。以上方法盡管是針對(duì)實(shí)時(shí)監(jiān)測(cè)要求提出的，但它完全可用于后處理情況。電離層擾動(dòng)的 GPS 探測(cè)方案，主要分后處理和實(shí)時(shí)兩種情況，靜、動(dòng)態(tài)實(shí)時(shí)方案基本相同，差別主要取決于硬件要求。試驗(yàn)結(jié)果表明，利用 ACEVS 研究基于GPS 的隨機(jī)電離

13、層活動(dòng)的監(jiān)測(cè)方法的設(shè)想是基本可行的；所給出的框架方案可作為設(shè)計(jì)各類利用單臺(tái)(靜、動(dòng)態(tài))雙頻 GPS 接收機(jī)監(jiān)測(cè)電離層活動(dòng)的方法的參考方案之一。5.5. 利用利用 GPSGPS 數(shù)據(jù)精確模擬電離層延遲的新構(gòu)想數(shù)據(jù)精確模擬電離層延遲的新構(gòu)想電離層蝕因子法及初步實(shí)現(xiàn)電離層蝕因子法及初步實(shí)現(xiàn)提出了 IPP 點(diǎn)的電離層蝕因子及其影響因子的概念，給出了簡(jiǎn)便的計(jì)算方法，進(jìn)而提出了一種利用 GPS 數(shù)據(jù)確定電離層延遲改正模型的新方法電離層蝕因子法。電離層蝕因子及其影響因子，能夠根據(jù)電離層隨周日、季節(jié)、半年和周年的變化，將適應(yīng)于不同季節(jié)的電離層延遲模型有效結(jié)合起來。研究表明，利用蝕因子法模擬的電離層延遲的改正精

14、度與利用電離層無關(guān)觀測(cè)的消除電離層延遲的精度很接近，使得單頻 GPS 觀測(cè)的電離層延遲的改正精度有望實(shí)現(xiàn)突破性提高，從而接近雙頻 GPS 觀測(cè)自校正電離層延遲的精度。同時(shí)，由于它具有很好的描述和區(qū)分電離層日間和夜間的能力，所以很適合模擬高動(dòng)態(tài)低軌衛(wèi)星的星載單頻 GPS 觀測(cè)數(shù)據(jù)的電離層延遲的變化特性。6.6. 高精度修正星載單頻高精度修正星載單頻 GPSGPS 低軌衛(wèi)星的電離層延遲的新對(duì)策低軌衛(wèi)星的電離層延遲的新對(duì)策APR-IIAPR-II 方案，即空基方案，即空基 APRAPR 方案方案分析了現(xiàn)有方法無法保證高精度和高可靠性地進(jìn)行電離層分層這一嚴(yán)重不足；利用實(shí)測(cè)數(shù)據(jù)模擬全球電離層模型和建立高

15、精度區(qū)域格網(wǎng)電離層模型，初步分析了在全球范圍內(nèi)尋找若干個(gè)電離層結(jié)構(gòu)和活動(dòng)相對(duì)較有規(guī)律的局部區(qū)域的可行性；設(shè)計(jì)了在選定的局部電離層區(qū)域，聯(lián)合處理地基和低軌空基用戶的GPS 觀測(cè)數(shù)據(jù)有效進(jìn)行電離層分層的具體方法，給出了相應(yīng)的精度估計(jì)公式。初步的精度估算和試算結(jié)果表明，這種在局部區(qū)域進(jìn)行有效電離層分層的設(shè)想及給出的實(shí)施方法是可行的。進(jìn)而系統(tǒng)性地提出了一種用于星載單頻 GPS 接收機(jī)精密測(cè)軌中電離層延遲改正的綜合方法APR-II 方案。地面 GPS 數(shù)據(jù)進(jìn)行的精選優(yōu)質(zhì)文檔-傾情為你奉上專心-專注-專業(yè)兩個(gè)初步模擬計(jì)算結(jié)果顯示，利用 APR-II 可滿足低軌衛(wèi)星等低軌航天器精密測(cè)軌時(shí)的電離層延遲的高精度

16、改正要求。精選優(yōu)質(zhì)文檔-傾情為你奉上專心-專注-專業(yè)Study on the New Methods of Correcting Ionospheric Delay and Ionospheric Model Using GPS DataAbstractRecently, according to the requirements of some important GPS research subjects in the fields of Geodesy, Geophysics, Space-Physics and navigation in China, we studied syste

17、matically how to correcting the effects of the ionosphere on GPS, with high-precision and accuracy. As the parts of the main contributions, the research projects focus mainly on how to improve GPS surveying by reducing ionospheric delay for dual/single frequency kinematic/static users: high accuracy

18、 correction of ionospheric delay for single/dual frequency GPS users on the earth and in space, China WAAS ionospheric modeling and the theory and method of monitoring of ionosphere using GPS. KEYWORDS:GPS ionospheric monitoring, ionospheric delay, GPS Wide Area DifferentialThe main contents of this

19、 Ph.D paper consist of two parts:Fisrt part-the outline of research background and the systematic introduction and summarization of the previous research results of this work. Second part-the main contribution and research results of this paper are focused on as follows:(1) How to use the measuremen

20、ts of a dual frequency GPS receiver to determine the ionospheric delay correction model for single frequency GPS of a local range;(2) How to separate the instrumental biases with the ionospheric delays in GPS observation;(3) How to establish a large range grid ionosphere model and use the GPS data o

21、f Chinese crust movement observation network to investigate the change law of ionospheric TEC of China area; (4) How to improve the effectiveness of correcting ionospheric delays for WAASs users under adverse conditions.精選優(yōu)質(zhì)文檔-傾情為你奉上專心-專注-專業(yè)(5) How to establish the basic theory and the corresponding

22、 framework of monitoring the stochastic ionospheric disturbance using GPS(6) How to improve the modelling ability of ionospheric delay according to its diurnal, seasonal, annual variations based on GPS;(7) How to meet the demand of correcting the ionospheric delay of high-precision orbit determinati

23、on for low-earth satellite using a single frequency GPS receiver1 Extracting (local) ionospheric information from GPS data with high-precision The factors are systematically described and analyzed which limit the precision of using GPS data to extract ionospheric delays. The precision of determining

24、 ionospheric delay using GPS is improved based on the further research of the related models and methods. The main achievements of this work include the some aspects as follows:(1) Based on a simple model with constant number of parameters, which consists of a set of trigonometric series functions,

25、a generalized ionospheric model is constructed whose parameters can be adjusted. Due to the property of selecting the different parameters according to the change law of ionospheric delay, the new model has better availability in the field of the related theoretic research and engineering applicatio

26、n. The experimental results show that the model can indicate the characteristic of ionospheric actions, improves further the modeling ability of local ionosphere and may be used to correct efficiently ionospheric delay of the single frequency GPS uses serviced by DGPS. (2) Different calculating sche

27、mes are designed which are used to analyze in detail the characteristics of the effect from instrumental bias (IB) in GPS observations on determining ionospheric delays. IB is different from noise in GPS observations. The experimental results show that the effect of IB is much larger than that of th

28、e noise on estimating ionospheic delay, and IB can cause ionospheric delay measurements to include systematic errors of the order of several meters. Therefore, one must significantly take notice of IB and remove its negative effect, and should not casually consider IB as part of noise whenever GPS d

29、ata are used to fit ionospheric model or to directly calculate ionospheric delay.(3) Stability of IB is studied with a refined method for separating it from ionospheric delay using multi-day GPS phase-smoothed code data. The experimental results show that, by using averaging of noise with phase-smoo

30、thed code observation，the effect of noise on separating IB from ION can be efficiently reduced, and satellite bias plus 精選優(yōu)質(zhì)文檔-傾情為你奉上專心-專注-專業(yè)receiver bias are relatively stable and may be used to predict the IBs of the next session or even that of the next several days.(4) A new algorithm about stat

31、ic real time determination of ionospheric delay is presented on the basis of the predicted values of IB and the technique of real time averaging of noise and weighted-adjustment of dual P-code and carrier phase measurements. The preliminary results show that the new method, which is by post-processi

32、ng phase-smoothed code data to calculate the IB and then with them to predict and to correct the IB of data needed to remove its effects in real time in the next observation periods, has relatively better accuracy and effectiveness in estimating ionospheric delay. It is very obvious that the scheme

33、can relatively decrease the number of unknown parameters, can efficiently reduce the main negative effect from instrumental bias, and can be easily used to directly and precisely determine ionospheric delay with dual-frequency GPS data. Hence, the method may be considered as an available scheme to d

34、etermine ionospheric delays for WAAS and many other large range GPS application systems.2 A method of constructing large range (regional and global) high-precision grid ionospheric modelthe Different Area for Different Stations (DADS) and its application in ChinaBased on the systematic and further r

35、esearch of the principle and methods of establishing grid ionospheric model (GIM), a new method of establishing a GIM - Different Areas for Different Stations (DADS) is investigated which is advantageous for considering the local characters of ionosphere, avoiding the effects of the geometrical cons

36、truction of GPS reference network on estimating the external precision of the GIM, and improving the precision of calculating model parameters. The above results are used to make a preliminary estimation of the latent precision that can be obtained by establishing a large range high precision grid i

37、onospheric model based on the Chinese crust movement observation network, and to investigate the possibility that the GIM provides high-precision ionospheric correction, and to identify the relevant problems which need to be solved for the planned GPS Wide area Augmentation System (WAAS) of China.3

38、A method of efficiently correcting ionospheric delays for WAASs users under typical adverse conditions the Absolute Plus Relative Scheme (APR-I)The commonly used WAASs DIDC received by single frequency GPS receivers can usually provide the effective correction of the ionospheric delays for the users

39、 精選優(yōu)質(zhì)文檔-傾情為你奉上專心-專注-專業(yè)under normal conditions and in the fields of calm ionosphere. However, the ionospheric delays cannot be efficiently accounted for during those periods when the WAAS cannot broadcast the DIDC values to users, or when the receivers cannot receive the DIDCs for whatever reason. Th

40、e ionospheric delay corrections will be less well known in cases when the variations of the ionospheric delays may be very large due to ionospheric disturbances. The above difficulties cannot be avoided to be encountered and must be solved for the WAAS.For this, a new ionospheric delay correction sc

41、heme for single frequency GPS datathe APR-I scheme is proposed which can efficiently address the above problems. 1) The theoretic basis of constructing the APR-I Scheme The WAAS can provide high-precision absolute ionospheric delay estimates when it operates properly. Meanwhile, a single frequency G

42、PS receiver serviced by the WAAS can efficiently determine the relative variation of the ionospheric delays between two arbitrary epochs even under adverse conditions if without considering observation noises. 2) On the APR-I SchemeBased on a robust recurrence procedure and an efficient combination

43、approach between absolute ionospheric delays and ionospheric relative changes, the APR-I scheme is present which is an new method of correcting ionospheric delay for single frequency GPS user. The formula of estimating the precision of the APR-I scheme is given. An implementation approach of the APR

44、-I scheme is analyzed as well.The experimental results discussed above show that the APR-I scheme not only retains the characteristic of high accuracy of the DIDC from the WAAS under normal ionospheric and reception conditions, but also has relatively better correction effectiveness under different

45、abnormal conditions. The implementation of this method need not change the present basic ionospheric delay correction algorithm of the WAAS. In addition, the APR-I method does not impose new demands on receiver hardware, and only requires a few improvements to receiver software. Hence it can be easi

46、ly used by single frequency GPS users.4 A new theory of monitoring the random signal Auto-Covariance Estimation of Variable Samples(ACEVS) and its application in using GPS to monitor the random ionosphere A new approach for monitoring ionospheric delays is found and developed, based 精選優(yōu)質(zhì)文檔-傾情為你奉上專心-

47、專注-專業(yè)on the characteristic of time series observation of GPS, an investigation of the statistical properties of the estimated auto-covariance of the random ionospheric delay when changing the number of samples in the time series, the development of the related basic theory and the corresponding fram

48、ework scheme, and the further research of using GPS and the above research results to study ionosphere.The concrete work is as follows:1) Studied the Auto-Covariance Estimation of Variable Samples (ACEVS) From a general mathematical aspect, the basic model of ACEVS is established. The theoretic and

49、approximate solution formulas for ACEVS are derived based on the improvement of theory of white noise and then a test raw of the state of a random signal is established based on ACEVS;2) Verified and modeled the possibility of using ACEVS to test the change of state of stochastic delaysThe possibili

50、ty of using ACEVS to monitor ionosphere is verified in terms of theory. Also it is found that the statistical property of ACEVS is sensitive to the change of the random ionospheric delay, on the basis of modeling the characteristics of ACEVS using a dual frequency GPS receiver. The application condi

51、tions of using ACEVS to monitor the variation of TEC extracted by GPS data are preliminarily discussed and analyzed as well.3) Established a preliminary framework scheme of using GPS to monitor the disturbance of random ionospheric delay.According to ACVES and all other results of the above and the

52、characteristic of the time series observations of GPS, a preliminary framework scheme for monitoring the disturbance of random ionospheric delay using GPS is established. Although this method is proposed for real time monitoring, it can be easily applied to post-processing of GPS data. The framework

53、 scheme based on ACVES can be used to design many practical schemes for monitoring ionosphere variation using a (static or kinematic) dual frequency GPS receiver. 5 A new method of modelling ionospheric delay using GPS data Ionospheric Eclipse Factor Method (IEFM) The Ionospheric Eclipse Factor (IEF

54、) and its influence factor (IFF) of Ionospheric Pierce Point (IPP) is present and a simple method of calculating the IEF is also given. By combining the IEF and IFF with the local time t of IPP, a new method of modelling ionospheric delay using GPS data Ionospheric Eclipse Factor Method 精選優(yōu)質(zhì)文檔-傾情為你奉

55、上專心-專注-專業(yè)(IEFM) is developed. The IEF and its IFF can efficiently combine the different ionospheric models for different seasons according to the diurnal, seasonal and annual variations of ionosphere. The preliminary experimental results show that the correction accuracy of the ionospheric delay modeled by IEFM is very close to that of using the ionosphere- free observation to correct directly the ionospheric delay, that is, the precision of using IEFM to model ionospheric delay for single GPS users seems to has a breakthrough improvement and be simi