外文翻譯 GPS

1、第一篇 中英文互譯外文原文Recently, according to the requirements of some important GPS research subjects in the fields of Geodesy, Geophysics, Space-Physics and navigation in China, we studied systematically how to correcting the effects of the ionosphere on GPS, with high-precision and accuracy. As the parts o

2、f 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 correction of ionospheric delay for single/dual frequency GPS users on the earth and in space, China WAAS ionosph

3、eric modeling and the theory and method of monitoring of ionosphere using GPS.The main contents of this 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 c

4、ontribution and research results of this paper are focused on as follows:(1) How to use the measurements 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 del

5、ays in GPS observation;(3) How to establish a large range grid ionosphere model and use the GPS data of 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 unde

6、r adverse conditions.(5) How to establish the basic theory and the corresponding 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 th

7、e demand of correcting the ionospheric delay of high-precision orbit determination for low-earth satellite using a single frequency GPS receiver 1 Extracting (local) ionospheric information from GPS data with high-precisionThe factors are systematically described and analyzed which limit the precisi

8、on of using GPS data to extract ionospheric delays. The precision of determining 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 n

9、umber of parameters, which consists of a set of trigonometric series functions, 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 availa

10、bility in the field of the related theoretic research and engineering application. 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 o

11、f the single(2) Different calculating schemes 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 estimating ionospheic delay, and IB

12、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 data are used to fit ionospheric model or to dir

13、ectly 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 showthat, by using averaging of noise with phase-smoothed code observation，the effect of noise on sep

14、arating IB from ION can be efficiently reduced, and satellite bias plus 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 static real time determination of ionospheric delay is presented on the b

15、asis 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-processing phase-smoothed code data to calculate the IB and then with them to

16、 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 can relatively decrease the number of unknown parameters, can efficie

17、ntly 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 determine ionospheric delays for WAAS and many other large range GPS a

18、pplication 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 research of the principle and methods of establishing grid ionospheric

19、 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 construction of GPS reference network on estimating the external precisio

20、n 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 ionospheric model based on the Chinese crust movement observation netw

21、ork, and to investigate the possibility that the GIM provides high-precision ionospheric correction, and toidentify the relevant problems which need to be solved for the planned GPS Wide area Augmentation System (WAAS) of China.3 A method of efficiently correcting ionospheric delays for WAASs users

22、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 under normal conditions and in the fields of calm ionosphere. However

23、, 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. The ionospheric delay corrections will be less well known in cases when the variations of the

24、 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 scheme for single frequency GPS datathe APR-I scheme is proposed which can efficiently addres

25、s the above problems.1) The theoretic basis of constructing the APR-I SchemeThe WAAS can provide high-precision absolute ionospheric delay estimates when it operates properly. Meanwhile, a single frequency GPS receiver serviced by the WAAS can efficiently determine the relative variation of the iono

26、spheric 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 approach between absolute ionospheric delays and ionospheric relative changes, the APR-I schem

27、e 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-I scheme is analyzed as well.The experimental results discussed above show that the APR-I sch

28、eme not only retains the characteristic of high accuracy of the DIDC from the WAAS under normalionospheric and reception conditions, but also has relatively better correction effectiveness under different abnormal conditions. The implementation of this method need not change the present basic ionosp

29、heric 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 easily used by single frequency GPS users.4 A new theory of monitoring the random signal Auto-Covar

30、iance Estimation of Variable Samples(ACEVS) and its application in using GPS to monitor the random ionosphereA new approach for monitoring ionospheric delays is found and developed, based on the characteristic of time series observation of GPS, an investigation of the statistical properties of the e

31、stimated 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 framework scheme, and the further research of using GPS and the above research results to study ionosphere.The concrete w

32、ork 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 approximate solution formulas for ACEVS are derived based on the improvement of theory of white noise and then a test

33、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 possibility of using ACEVS to monitor ionosphere is verified in terms of theory. Also it is found that the statistical property

34、 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 conditions of using ACEVS to monitor the variation of TEC extracted by GPS data are preliminarily discussed and analyzed as

35、 well.3) Established a preliminary framework scheme of using GPS to monitor thedisturbance of random ionospheric delay.According to ACVES and all other results of the above and the characteristic of the time series observations of GPS, a preliminary framework scheme for monitoring the disturbance of

36、 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 scheme based on ACVES can be used to design many practical schemes for monitoring ionosphere variation using a (static

37、 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) and its influence factor (IFF) of Ionospheric Pierce Point (IPP) is present and a simple method of calculating the IEF

38、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 (IEFM) is developed. The IEF and its IFF can efficiently combine the different ionospheric models for different seasons according to

39、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

40、 of using IEFM to model ionospheric delay for single GPS users seems to has a breakthrough improvement and be similar to that of using the corresponding dual frequency GPS data to correct directly the ionospheric delays. The IEFM also suits to model the ionospheric delays for a kinematic basedsingle

41、 GPS receiver embeded in low-earth satellite with high rapid due to its good ability in distinguishing the daytime and nighttime of the earth ionosphere for an IPP.6 A new strategy of correcting ionospheric delay for high-precision orbit determination for low-earth satellite using a single frequency

42、 GPS receiver -the APR-II scheme, i.e., Space-based APR schemeAnalyzed the shortcomings of using the previous methods to divide with high accuracy the earth ionosphere into different layers. Used GPS data to model globalionospheric TEC. Established a high precision grid ionospheric model. Discussed

43、the possibility of finding out some local areas whose ionospheric construction and action have relatively better obvious law with respect to the other areas on a global scale. Designed a scheme for combining GPS-grounded data with GPS-spaced data to divide efficiently the ionosphere into some layers

44、. Given the corresponding formula of estimating the precision of the scheme. The preliminary precision estimation and the experimental results show the possibility and property of the above idea of dividing ionosphere into different layers according to application requirement and its implementation

45、scheme. Based on the above research, the APR-II scheme is presented which is a new and combined method of correcting the ionospheric delays of high-precision orbit determination for low-earth satellite using a single frequency GPS receiver. The preliminary experimental results based on two different

46、 sets of GPS-grounded data show that the APR-II scheme can provide the effective ionospheric delay correction for high-precision orbit determination for low-earth satellite.中文翻譯根據(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

47、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)電離層的理論和方法等方面。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,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

48、影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: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

49、。1. (局部)電離層延遲的高精度提取系統(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，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

50、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

51、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. 一種構(gòu)建大規(guī)模(區(qū)域性和全球性)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)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，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

52、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. 不利條件下為WAAS的單頻GPS用戶提供電離層延遲改正的新方法APR-I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離層延遲改正要求，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APR-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