电离层延迟改正模型算法的研究与探讨

发布时间：2018-09-10 20:00

【摘要】：电离层是地球表面从50千米到几千千米的大气,由于太阳辐射的原因,该区域的大气被弱电离化,产生大量的自由电子和离子。这些粒子对无线电波产生很大影响,引起的GNSS延迟可达数米甚至数百米,是目前GNSS应用中最主要的误差源之一,因此在进行无线电导航与应用时,需要进行电离层延迟改正。此外,卫星导航系统正进入新纪元,目前除了现有的GPS和GLONASS全球导航系统外,中国的北斗导航系统、欧洲的Galileo导航系统以及区域导航系统,如QZSS、NAVIC系统,均在迅猛发展。基于这种现状,本文对电离层延迟改正开展了一系列的研究工作。本文的主要工作和创新点如下:1.文中详细介绍GPSK8、Galileo NeQuick G、BDSK8、BDSK14、BDSSH广播电离层延迟改正模型的用户算法,并且评估了几种模型在不同区域的性能,为北斗全球广播电离层模型的性能优化提供了必要的支撑与保障。在中国区域,BDSSH模型性能最好,改正率均在75%以上,RMS精度为5TECU以内,模型改正效果由高到低依次为BDSSH、BDSK14、NeQuick G、BDSK8、GPSK8模型;在全球范围,也是BDSSH模型精度最好,改正率在70%以上,RMS精度为5TECU内,模型改正效果由高到低依次为BDSSH、NeQuick G、GPSK8模型。2.本文基于GPS、GLONASS、BDS、Galileo四系统的观测信息,开展了多系统的电离层VTEC建模研究,该策略能够更充分地利用当前多GNSS导航的特点,在一定程度上提高了电离层信息的拟合精度,为卫星导航应用与电离层研究工作提供了更加有效、可靠的途径。建模结果在北半球高纬和中纬地区的精度要比南半球好,并且精度比较稳定,与CODE最终GIM相比,平均偏差在1TECU左右,RMS在1.5TECU左右;建模结果无论在南半球还是北半球,中纬和高纬地区的建模结果都要比低纬好,北半球低纬地区,平均偏差为2.77TECU,RMS为3.92TECU;南半球低纬地区,平均偏差为2.33TECU,RMS为3.34TECU。3.本文开展了电离层图(GIM)的评估工作,主要讨论了CODE、ESA、UPC、JPL、CAS、IGS和iGMAS几家机构的最终、快速和预报的GIM精度,为GNSS单频用户进行高精度导航和科研工作者开展电离层信息的精密研究提供了有力保障。CODE的最终GIM精度在中纬和低纬地区的精度都是最好的,在中纬和低纬地区STD依次为1.78、2.84TECU;在高纬地区,JPL的最终GIM精度最好,STD为1.76TECU。JPL的快速GIM精度是所有快速GIM中精度最好的,在高纬、中纬和低纬地区的STD依次为1.77TECU、1.91TECU和3.14TECU。此外,预报GIM要比最终和快速GIM精度差一些。4.本文采用ARMA时间序列模型进行了电离层信息的建模与预报研究,为GNSS用户提供了高精度的实时电离层延迟改正模型,同时该方法也为电离层的研究工作提供了一条有效、可行的途径。预报结果在北半球的精度要比南半球高一些。在北半球,预报31天时,预报精度比较稳定,平均RMS为3.53TECU;随着纬度的降低,预报精度也随之降低;在中国区域,预报40天的预报精度比较稳定,平均RMS为4.01TECU;白天的预报精度要比夜晚好,互差在0.5TECU内。
[Abstract]:Ionosphere is the atmosphere of the earth's surface from 50 km to several thousand km. Due to solar radiation, the atmosphere in this region is weakly ionized, producing a large number of free electrons and ions. These particles have a great impact on radio waves, resulting in GNSS delays up to several meters or even hundreds of meters. In addition, satellite navigation systems are entering a new era. Beidou navigation systems in China, Galileo navigation systems in Europe and regional navigation systems, such as QZSS and NAVIC systems, are developing rapidly, in addition to existing GPS and GLONASS global navigation systems. Based on this situation, a series of research work on ionospheric delay correction has been carried out in this paper. The main work and innovations of this paper are as follows: 1. The user algorithms of GPSK8, Galileo NeQuick G, BDSK8, BDSK14, BDSSH broadcasting ionospheric delay correction models are introduced in detail, and the performances of several models in different regions are evaluated. In China, the BDSSH model has the best performance, the correction rate is above 75%, the RMS precision is within 5 TECU, and the correction effect is BDSSH, BDSK14, NeQuick G, BDSK8, GPSK8 in turn. In this paper, based on the observation information of GPS, GLONASS, BDS and Galileo, a multi-system ionospheric VTEC modeling study is carried out. The strategy can make full use of the characteristics of current multi-GNSS navigation to a certain extent. The precision of the ionospheric information fitting is better than that of the southern hemisphere in the high and middle latitudes of the northern hemisphere. Compared with the final GIM of CODE, the average deviation is about 1 TECU and the RMS is about 1.5 TECU. In both the southern and Northern hemispheres, the modelling results in the middle and high latitudes are better than those in the low latitudes. In the low latitudes of the northern hemisphere, the mean deviation is 2.77 TECU and the RMS is 3.92 TECU. In the low latitudes of the southern hemisphere, the mean deviation is 2.33 TECU and the RMS is 3.34 TECU.3. The ultimate, fast and predictive GIM accuracy of S and iGMAS provides a powerful guarantee for GNSS single-frequency users to conduct high-precision navigation and researchers to conduct precise research on ionospheric information. In the high latitude region, the final GIM precision of JPL is the best, and the fast GIM precision of STD is 1.76TECU.JPL is the best among all the fast GIMs. The STD in the high latitude, middle latitude and low latitude regions is 1.77 TECU, 1.91 TECU and 3.14 TECU respectively. In addition, the predicted GIM precision is lower than that of the final and fast GIM. 4. In this paper, the ARMA time series model is used to study the ionosphere. Modeling and forecasting of information provide GNSS users with high precision real-time ionospheric delay correction model, and this method also provides an effective and feasible way for the study of ionosphere. RMS is 3.53 TECU; with the decrease of latitude, the forecast precision decreases; in China, the forecast precision of 40 days is relatively stable, with an average RMS of 4.01 TECU; the forecast precision of daytime is better than that of night, and the difference is within 0.5 TECU.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P228.4

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