外文翻译 GPS

1、第一篇 中英文互译外文原文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.中文翻译根据当前大地测量、地球物理、空间物理和导航等领域的科学研究和工程应用中的若干重要GPS科研项目的需要，近年来，我们系统研究了电离层延迟的高精度模拟和改正方法。本文报告的内容，是我们研究工作的部分贡献，主要涉及基于GPS的电离层监测及延迟的高精度改

47、正的理论与方法的研究：如何通过修正静、动态单、双频用户的电离层延迟影响，进一步改善GPS 测量的精度和可靠性；增强型GPS广域差分系统的电离层模拟及利用GPS监测电离层的理论和方法等方面。本文主要包括两方面的内容：一、研究背景的一般性描述及相关基础研究的系统总结和介绍,主要涉及：地球电离层研究意义, 地球电离层探测技术与相关理论研究的内容,现代大地测量中电离层问题的由来、严重性与新课题, 地球电离层的基本特性及其对电波传播的影响，GPS定位的基本理论与方法，电离层延迟对GPS测量的影响，GPS的电离层延迟改正的基本方法，基于GPS的电离层研究的基本原理与方法等。进而论述了解决GPS的电离层延迟

48、影响的重要性和切入点。二、具体研究工作的系统报告，主要集中在以下几方面:研究如何利用单台双频GPS接收机的观测信息确定电离层延迟改正模型，为小范围的单频用户服务；研究如何实时分离GPS观测中的仪器偏差与电离层延迟；研究如何建立较大区域的电离层格网模型，进而初步设想利用中国地壳运动观测网络深入研究我国领域的电离层的电子浓度变化规律；研究单频用户在不利条件下，如何更好地利用电离层延迟改正信息； 研究利用GPS监测随机电离层扰动的基本理论和框架方案；研究如何综合顾及电离层的周日、季节和年变化，进一步提高利用GPS模拟电离层延迟的能力；研究如何实现星载单频GPS低轨卫星的精密测轨中的电离层延迟改正要求

49、。1. (局部)电离层延迟的高精度提取系统论述和分析了影响利用GPS观测精确提取电离层延迟信息的各类因素。通过对有关模型和方法问题的深入研究，进一步提高了利用GPS提取电离层延迟信息的精度。主要包括：（1）将参数固定的三角级数函数电离层模型，扩展为更适用于理论研究和实际应用的参数可调型广义形式，实现了根据电离层延迟时空变化特征，选择不同的特征参数模拟电离层延迟的影响。试算结果表明，它能较好地反映电离层活动特性，提高了局部电离层延迟模拟能力，适用于DGPS系统修正其服务区域内的单频GPS用户的电离层延迟。（2）设计了几种不同的计算方案，用于分析仪器偏差对确定电离层延迟的影响的特点。研究表明，仪器

50、偏差对求解电离层延迟的影响远大于观测噪声的影响，给电离层延迟观测值带来高达数米的系统误差。利用GPS观测数据求解电离层模型或直接计算斜距电离层延迟时，都须慎重处理仪器偏差，不应简单把其作为噪声处理;（3）利用相位平滑测码数据进一步精化了仪器偏差分离方法，探讨了仪器偏差的稳定性。研究发现，新方法可有效克服噪声对分离仪器偏差的影响，而且仪器偏差相对稳定并可有效进行测段间及数日间预报。（4）基于实时平均去噪和码、相位观测数据的加权联合处理的思想，提出了一种实时分离仪器偏差和求解电离层延迟量的新方案。算例表明，新方法通过采用平均去噪分离方法后处理相位平滑测码数据，求出仪器偏差并对需要实时处理仪器偏差的

51、观测数据进行预报改正，直接利用观测值确定电离层延迟量，待估参数少、能消除仪器偏差的大部分影响，具有较好的精度，可作为WAAS及其他GPS网络系统确定电离层延迟的可行的参考方案。2. 一种构建大规模(区域性和全球性)高精度格网电离层模型的新方法站际分区法及其在中国的初步实现在系统深入研究了格网电离层模型建立原理与方法的基础上，为避免基准站网的几何结构对模型精度估计的影响，充分顾及电离层延迟影响的局部特性，进一步提高格网电离层模型的构建精度，提出了一种新的格网电离层模型构建方法站际分区格网法。在以上研究的的基础上，估计了利用地壳运动观测网络的基准网建立格网电离层模型的精度，初步探讨中国域内拟建立的

52、广域差分GPS增强系统，采用格网电离层模型提供电离层改正信息的可行性及有待进一步研究的问题。3. 不利条件下为WAAS的单频GPS用户提供电离层延迟改正的新方法APR-I方案在正常条件和平静电离层区域，WAAS能够满足单频用户的电离层延迟改正要求，但当用户无法正常获取电离层延迟改正信息时，如在差分系统突然中断信息发送或用户步入无法正常接收差分改正信息的位置等不利条件下，单频GPS接收机不能有效进行实时电离层延迟改正，尤其在电离层活动异常区域如电离层扰动条件下，实时差分改正效果将受到严重影响。这些问题在WAAS的实际运行中是难以避免和必须解决的。而以往的研究结果，均为后处理方法，不能满足(准)实时处理电离层扰动的要求。针对这种状况，我们通过设计能有效结合电离层延迟绝对量和相对变化量的抗差递推过程，提出了一种可在以上不利条件下有效实时改正单频GPS用户电离层延迟的方法APR-I方案。1）构建APR-I方案的理论依据WAAS正常运转和正常条件下可提供高精度的电离层延迟改正信息(绝对量)，而WAAS所服务区域内的单频GPS接收机在不利条件下也能有效提供电