测绘工程外文翻译(含中文原文).doc

中文翻译中文翻译 基于基于 GPSGPS 数据的电离层模型和电离层延迟改正新方法研究数据的电离层模型和电离层延迟改正新方法研究 摘要 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 关键词 GPS 的电离层监测 电离层延迟 GPS 广域差分 本文主要包括两方面的内容 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 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 1 1 局部局部 电离层延迟的高精度提取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 2 一种构建大规模一种构建大规模 区域性和全球性区域性和全球性 高精度格网电离层模型的新方法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 3 不利条件下为不利条件下为 WAASWAAS 的单频的单频 GPSGPS 用户提供电离层延迟改正用户提供电离层延迟改正 的新方法的新方法 APR IAPR I 方案方案 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离层延迟 变化量 相对量 且在不考虑噪声影响 可直接计算任意两观测历元间的电离 层变化量的近似值 2 提出 APR I 方案 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 研 究了一种新的单频 GPS 电离层延迟改正方案 称为 APR 方案 即 Absolute Plus Relative Scheme 给出了 APR I 方案的精度估计公式 分析实施 APR I 方案 的有效途径 研究表明 新方案既保留正常条件下差分电离层延迟信息的精确改正效果 也确保了在不利条件下单频 GPS 用户的电离层延迟改正效果 APR I 方案的实 施 不需改变 WAAS 原有的整体设计思想 对硬件无新的要求 只需对用户 GPS 软件稍加改进 实施简便 是 WAAS 和单频 GPS 用户均可接受和易于实现的 4 4 检测随机信号的新理论检测随机信号的新理论 变样本自协方差估计的提出变样本自协方差估计的提出 及其在及其在 GPSGPS 监测随机电离层扰动中的应用监测随机电离层扰动中的应用 根据 GPS 时序观测的特点 通过设计先研究样本时序变化时随机电离层折 射的自协方差估计的统计特性 再探讨利用 GPS 实时监测电离层活动的新方法 的思路 从基础理论的提出到框架方案的建立 系统深入研究了利用 GPS 监测 随机电离层扰动的基本理论与方法 具体包括 1 研究变样本自协方差估计 ACEVS 理论 从一般的数学意义上建立了 ACEVS 的基本模型 并在进一步扩展白噪声理 论的基础上 得到了 ACEVS 估计的理论和简化解式 即变样本自协方差估计的 统计模型参数估计解式 进而建立了随机信号扰动的诊断准则 2 ACEVS 估计应用于 GPS 电离层监测的可行性的理论证明与模拟分析 不仅从理论上证明了 ACEVS 应用于 GPS 电离层监测的可行性 而且利用双 频 GPS 数据也成功地模拟了随机电离层折射的 ACEVS 估计的特性 并发现 变 样本自协方差估计的统计特性对随机电离层延迟变化是敏感的 初步讨论和分 析了 GPS 观测提供的 TEC 变化也适用于 ACEVS 方法应用条件 3 建立利用 GPS 监测随机电离层扰动的框架方案 综合 ACEVS 理论及相关的结论和 GPS 时序采样的特点 初步给出一种基于 GPS 的电离层扰动监测的框架方案 以上方法尽管是针对实时监测要求提出的 但它完全可用于后处理情况 电离层扰动的 GPS 探测方案 主要分后处理和实时两种情况 静 动态实时方 案基本相同 差别主要取决于硬件要求 试验结果表明 利用 ACEVS 研究基于 GPS 的随机电离层活动的监测方法的设想是基本可行的 所给出的框架方案可 作为设计各类利用单台 静 动态 双频 GPS 接收机监测电离层活动的方法的参 考方案之一 5 5 利用利用 GPSGPS 数据精确模拟电离层延迟的新构想数据精确模拟电离层延迟的新构想 电离层蚀因子法及初步实现电离层蚀因子法及初步实现 提出了 IPP 点的电离层蚀因子及其影响因子的概念 给出了简便的计算方 法 进而提出了一种利用 GPS 数据确定电离层延迟改正模型的新方法 电离 层蚀因子法 电离层蚀因子及其影响因子 能够根据电离层随周日 季节 半 年和周年的变化 将适应于不同季节的电离层延迟模型有效结合起来 研究表 明 利用蚀因子法模拟的电离层延迟的改正精度与利用电离层无关观测的消除 电离层延迟的精度很接近 使得单频 GPS 观测的电离层延迟的改正精度有望实 现突破性提高 从而接近双频 GPS 观测自校正电离层延迟的精度 同时 由于 它具有很好的描述和区分电离层日间和夜间的能力 所以很适合模拟高动态低 轨卫星的星载单频 GPS 观测数据的电离层延迟的变化特性 6 6 高精度修正星载单频高精度修正星载单频 GPSGPS 低轨卫星的电离层延迟的新对策低轨卫星的电离层延迟的新对策 APR IIAPR II 方案 即空基方案 即空基 APRAPR 方案方案 分析了现有方法无法保证高精度和高可靠性地进行电离层分层这一严重不 足 利用实测数据模拟全球电离层模型和建立高精度区域格网电离层模型 初 步分析了在全球范围内寻找若干个电离层结构和活动相对较有规律的局部区域 的可行性 设计了在选定的局部电离层区域 联合处理地基和低轨空基用户的 GPS 观测数据有效进行电离层分层的具体方法 给出了相应的精度估计公式 初步的精度估算和试算结果表明 这种在局部区域进行有效电离层分层的设想 及给出的实施方法是可行的 进而系统性地提出了一种用于星载单频 GPS 接收 机精密测轨中电离层延迟改正的综合方法 APR II 方案 地面 GPS 数据进行的 两个初步模拟计算结果显示 利用 APR II 可满足低轨卫星等低轨航天器精密测 轨时的电离层延迟的高精度改正要求 Study on the New Methods of Correcting Ionospheric Delay and Ionospheric Model Using GPS Data Abstract 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 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 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 Differential 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 contribution 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 delays 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 WAAS s users under 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 the 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 precision The factors are systematically described and analyzed which limit the precision 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 number 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 availability 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 of the single frequency GPS uses serviced by DGPS 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 experimental results show that the effect of IB is much larger than that of the 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 data 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 smoothed code observation the effect of noise on separating 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 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 processing 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 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 determine 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 model the Different Area for Different Stations DADS and its application in China Based on the systematic and further research 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 construction 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 ionospheric 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 A method of efficiently correcting ionospheric delays for WAAS s users under typical adverse conditions the Absolute Plus Relative Scheme APR I The commonly used WAAS s 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 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 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 data the 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 GPS 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 Scheme Based on a robust recurrence procedure and an efficient combination 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 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 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 easily 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 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 framework 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 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 delays The possibility 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 conditions 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 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 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 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 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 similar to that of u