【作者】 李慧茹；

【导师】 杨志强；

【作者基本信息】 长安大学 ， 大地测量学与测量工程， 2013， 博士

【摘要】 电离层是近地空间环境的重要组成部分，电离层的研究可以促进人们认识日地空间系统的整体行为，进而更好地为人类的空间活动服务，因此电离层的研究具有重要的意义。近年来，随着人类空间活动和卫星通讯系统的增多，对电离层各种变化特征及规律（尤其是时空变化）的监测和反演的需求也越来越强烈。目前，利用GPS解算电离层总电子含量（Total Electron Content,TEC）已经成为监测电离层活动的主要技术，而国内外大大小小不同尺度、密度的连续运行GPS观测站网为电离层的局域、区域、全球特性研究提供了平台。国际GNSS服务中心（InternationalGNSS Service,IGS）从1998年开始提供每天的全球电离层TEC分布图（Global IonosphereMap，缩写为GIM），但是IGS各数据处理中心发布的电离层IONEX文件在时间和空间上的分辨率都不高，由于在中国范围内IGS的观测站数目不多，因此它的精度也不理想，并且IONEX文件并不是GPS特定的格式,它是非GPS用户使用IGS电离层产品的一种接口。因此通过建立一个区域的GPS观测站网，利用实时的GPS电离层观测数据建立电离层模型，监测、现报/预报电离层活动，可以为区域内单频GPS用户提供电离层延迟改正信息。本文正是基于这一背景，在西安地区选取4个GPS双频观测站网，采用kalman滤波对电离层的时空变化实时监测，并且选择地质统计学中常用的kriging方法重构了西安区域电离层TEC地图。本文的主要研究工作和成果如下：1.系统研究了GIPSY (GNSS-Inferred Positioning System)中周跳探测与修复的Turboedit算法，在此基础上对TurboEdit方法的周跳探测条件进行分析，对于该方法中每一历元之前的所有宽巷模糊度整体求平均的方法，采用滑动平均的方法替代，同时在电离层残差组合中，采用了相邻历元的载波相位电离层残差组合求差的方法，从而避免引入观测噪声较大的伪距电离层残差组合。实验表明：改进后的TurboEdit法对于发生在观测数据质量不好的周跳、Turboedit法的探测盲点以及频繁周跳的探测能力都有所提高。2.进行倾斜路径电离层实时提取时，利用伪距提取的TEC P修正载波相位提取TEC的方法，实例结果表明：修正后的电离层TEC与伪距提取的倾斜路径电离层TECP吻合较好，能够反映出的伪距观测提取电离层TEC P的趋势走向，但是修正后的电离层TEC数据更加平滑、集中；采用切比雪夫（Chebyshev）多项式对GPS卫星轨道进行拟合内插；计算了电离层穿刺点的位置坐标。3.采用Kalman滤波估计出每个观测历元的电离层模型系数以及测站和卫星的硬件延迟，达到了实时监测电离层活动的目的。将GPS观测数据直接解算的电离层TEC与kalman滤波算法处理后的垂直TEC进行比较，结果表明：kalman滤波解算的电离层垂直TEC能够实时反映电离层TEC的活动变化。4.采用Kriging方法对西安区域电离层TEC地图进行了重构，并通过CODE分析中心提供的最终TEC产品对本文解算结果进行了验证，结果表明本文解算结果与CODE的结果基本相当。更多还原

【Abstract】 Ionosphere is an important part of terrestrial space environment. The study ofionosphere can expand our knowledge of integral activities of solar and terrestrial spacesystem and further provide better service for human space activities; therefore, the study ofionosphere is of great significance. In recent years, with the increasing of human spaceactivities and satellite communication systems, it has a strong demand for monitoring andInverting of various variation characteristics and laws (especially the temporal and spatialvariation) of the ionosphere.At present, utilizing GPS to calculate the Total Electron Content (TEC) has become theprimary technology to monitor the ionosphere activities. The continuous operating GPSobserving station networks of diverse scales and densities both at home and abroad providethe platform for local, regional and global ionosphere research. Since1998, the InternationalGNSS Service (IGS) has began to broadcast Global Ionosphere Map everyday (GIM),however, the ionosphere IONEX Files issued by the IGS Analysis Centers do not have highresolving capability both in time and space. Since there are few IGS observing stations inChina, its accuracy is not desirable; besides, IONEX Files is a non-GPS user interface forusing IGS ionosphere products rather than the specific format of GPS. So we need to set up aregional GPS observation station network and set up a ionosphere model based on real-timeGPS observation data to monitor, broadcast/forecast the ionosphere activities, which canprovide single frequency GPS users the delayed and corrected information of ionosphere.Under this background, selecting4GPS double frequency observation station networks,adopting the kalman filtering to monitor the real-time the temporal and spatial variation ofionosphere, and choosing the kriging method that is frequently-used in geographic statistics toreconstruct the ionosphere TEC map at Xi’an in this paper.The main work and achievements of the paper are as follows:1. The TurboEdit algorithm is introduced in this paper which detected and repaired cycleslips in GIPSY, and the detection conditions of cycle slip is analyzed to TurboEdit algorithm.Moving average is used to replace overall average of all data before each epoch in theWide-lane ambiguity, at the same time Geometry-free Combination is improved bydifferenced in the adjacent epoch. Experimental results show that the improved algorithm ismore effective than TurboEdit algorithm for the problem of blind spots in TurboEditalgorithm and high cycle slip rates and bad multipath condition.2. Using the pseudo range method to extract revised carrier phase extracting TECPso as to real-time extract the slant path ionosphere in this paper. The result shows that the revisedionosphere TEC well coincides with slant path ionosphere TECPextracted from pseudo rangeobservation, which is able to reflect the trend of ionosphere TECPextracted from pseudorange observation, and the revised ionosphere TEC data are more smooth and centralized.Using the Chebyshev polynomials to interpolate the GPS Satellite orbits and calculates thecoordinates of ionosphere puncture points in this paper.3. Using the Kalman filtering to estimate ionosphere mode coefficients of every epoch aswell as the hardware delay of observation stations and satellites in this paper., achieving thepurpose of real-time monitoring of the ionosphere activities. Compared the directly calculatedionosphere TEC of GPS observation data with the vertical TEC obtained by kalman filteringalgorithm the result shows that the latter can reflect the real-time change of ionosphere TECactivities.4. It applies kriging method to reconstruct the ionosphere TEC map in Xi’an region andverifies the calculated result through the final TEC products provided by CODE analysiscenter. The result shows that its calculated result in this paper is basically the same with thatof the CODE.更多还原