区域电离层GPS监测及应用研究
文献类型：学位论文
| 作者 | 黄逸丹 |
| 学位类别 | 硕士 |
| 答辩日期 | 2007-06-18 |
| 授予单位 | 中国科学院上海天文台 |
| 授予地点 | 上海天文台 |
| 导师 | 平劲松 |
| 关键词 | GPS VTEC 电离层延迟模型 单频观测 Klobuchar模型 电离层周日变化 |
| 中文摘要 | Ionospheric delay is one of the key error sources for GPS navigating and positioning applications. One method to correct the ionospheric delay is to use the broadcasted Klobuchar ionosphere model of GPS system. Usually, Klobuchar ionosphere model can only achieve 50% of the ionospheric effect because of the following two factors: using the fixed phase and a constant ionosperic delay at night time (9ns, based on L1 frequency). In actual case, the daily ionosperic delay of night and the phase vary with time and latitude. For regional GPS navigating and positioning applications, it’s necessary to modify the former Klobuchar ionosphere model so as to improve the precision for single frequency users. On the other hand, it’s a good way to correct ionospheric delay in GNSS by using dual-frequency observations. However, the dual-frequency GPS receivers are much expensive than the single-frequency GPS receivers. So, it’s necessary to find out some useful way to use single-frequency observations to solve the problem about Ionospheric delay. Considering above reasons, the main work and content of this paper is read as following: 1. To analyze the disadvantages of the former Klobuchar model of GPS and to develop an improved Klobuchar model. The phase of trigonometric function and the night delay are considered as variables with geographic latitude. In the model, we have increased the number of the original model parameters from 8 to 14. To accomplish the modeling algorithm, the parameters are firstly estimated to describe the diurnal variation of ionosphere (including period ,amplitude , initial phase, the average VTEC value in night ) using the least RMS; then, the Least Square method is applied to calculate the final 14 parameters of Klobuchar model. After analyzing, we have written out all codes for the new improved Klobuchar model using computer languages such as C, FORTRAN and C-shell. The codes are installed and run under LINUX system. The improved Klobuchar model will be used in Chinese regional GNSS system, which is being developed step by step. 2. In this paper, a method for estimating VTEC is proposed and carried out which takes advantage of real-time pseudo random code and carrier phase observation data obtained by a single-frequency GPS receiver. Preliminary results of VTEC and the VTEC-derivative will be presented and compared with results from dual-frequency GPS observations estimates. The proposed method in this paper may benefit the satellite-to-satellite occultation experiment in the joint martian exploration (YH-1 and PG-1) between China and Russia. |
| 英文摘要 | GPS系统中导航电文包括了电离层延迟预报，它采用的是Klobuchar模型。由于该模型的参数设置的缺陷，以及全球电离层的不确定因素，其改正精度仅达到50%左右，无法满足区域性高精度导航定位的要求。因此，本文基于区域卫星导航系统，针对区域电离层改正对原Klobuchar模型提出了改进，针对相位及夜间平场的周日变化特性，将原来的8个参数扩展到14个参数，并将这一方案进行了软件工程化，可为中国区域及其周边地区的电离层延迟预报服务。 在卫星导航、定位服务中，电离层延迟是主要误差源之一，通常通过双频观测的方法来消除它的影响。考虑到我国将来火星探测的需要，作为本文的另一个结果，探索了单频伪距-载波相位观测量求解观测站上空电离层垂直总电子含量，及其时间变化率的方法，并利用GPS观测进行实验计算。本文阐述了该方法的基本原理，给出了BJFS站的观测资料进行试算的例子。该方法与该GPS站双频观测的归算结果，以及IRI电离层模型进行了比较，得到了较好的结果。 本文的工作大致可以归纳成： 1、 分析了GPS导航电文中采用的Klobuchar模型的不足，在原有模型的基础上增加了三角函数相位以及线性函数夜间平场在电离层周日变化中的影响，将原来K氏模型的8参数增加到14参数，分析了电离层周日变化特性，实现了周日参数的提取，并在服务区域范围内通过最小二乘由周日参数拟合得到最后的14个参数。在Linux 操作系统下利用C-Shell、c语言及FORTRAN语言编写了该模型改正的软件代码，用于区域导航服务。 2、 探索了一种利用GPS/GNSS单频伪码-载波相位观测量求观测站上空电离层垂直总电子含量及其时间变化率的方法。阐述了该方法的原理并给出了利用BJFS站的观测进行解析的具体算例。与利用该GPS站双频观测解析的结果和电离层模型的结果进行了比较，三者结果一致，证明了方法的有效性。另外，本文提出的该方法，将对中俄合作火星探测器中萤火-1与Phobos-Grunt之间的掩星观测提供解析方法的参考。 |
| 语种 | 中文 |
| 公开日期 | 2011-07-01 |
| 页码 | 67 |
| 源URL | [http://119.78.226.72//handle/331011/14676]  |
| 专题 | 上海天文台_中国科学院上海天文台学位论文 |
| 推荐引用方式 GB/T 7714 | 黄逸丹. 区域电离层GPS监测及应用研究[D]. 上海天文台. 中国科学院上海天文台. 2007. |
入库方式： OAI收割
来源：上海天文台
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