多模GNSS实时电离层精化建模及其应用研究

发布时间：2018-03-14 07:24

本文选题：电离层延迟　切入点：GPS　出处：《武汉大学》2013年博士论文　论文类型：学位论文

【摘要】：电离层是日地空间环境的重要组成部分,认识电离层的结构和活动规律,是人类对自身生存环境认识和利用的重要基础。电离层的研究对于研究日地空间环境及高空大气各层之间的相互关系和作用,提高测速、定位、授时、导航等系统的精度等方面,都具有非常重要的价值。相比较于传统电离层探测技术,GNSS探测技术能够实现连续运行、高密度覆盖。目前,四大全球卫星导航系统(Global Navigation Satellite System, GNSS)并存与发展的局面已初步形成。随着多模CNSS连续运行跟踪站数量增加与观测数据质量不断提升,针对多模GNSS系统不同特点进行深入研究,开展基于多模GNSS系统的电离层建模十分必要。由于电离层模型、伪距观测值精度等因素影响,单频单点定位仅可获得分米至米级定位精度。通过不同频率组合,双频用户可以消除超过99%的电离层误差影响。但观测值组合放大了观测噪声,需要更多的时间实现双频PPP收敛。因此,进一步提高电离层模型精度,可有助于提高单频定位精度、加速双频PPP收敛速度。电离层延迟对单频导航用户影响很大,但导航系统自身提供的实时改正产品效果有限,难以获得高精度定位结果。因此,基于区域或者全球的跟踪站网络提供的实时观测数据流,建立实时电离层模型,能够有效提高服务区域内单频用户定位精度。同时,利用实时电离层模型能够实现高精度的电离层监测,有助于研究电离层扰动及不规则变化。本文针对电离层二维层析中的一些问题,对数据预处理、电离层提取方法等进行深入分析；利用实测GPS/Beidou数据建立中国区域电离层模型,分析多模系统对电离层模型、硬件延迟估计精度影响；分析GLONASS伪距频间偏差特性,提出一种先验改正的方法,可有效消除伪距频间偏差对GLONASS卫星电离层延迟提取的影响；利用区域密集的参考站,建立基于单颗卫星的精化电离层模型,提出一种基于精化电离层产品的双频PPP快速收敛算法；利用中国区域实时数据流开发了一套实时电离层模型系统,为中国区域用户提供实时电离层延迟产品,可应用于中国区域单频定位及电离层变化监测。本文的主要研究内容包括： 1.针对观测数据中钟跳问题,采用星间单差MW组合辅助非差MW、GF探测周跳、钟跳；对比分析了采用相位平滑伪距及组合观测值分解方法提取电离层延迟的精度；对中国区域电离层建模的布站选择进行分析,实验结果说明采用60个左右分布均匀的跟踪站即可获得较高的模型精度。 2.利用Beidou/GPS双模实测数据建立了中国区域电离层模型。在当前卫星、跟踪站分布状态下,利用单模Beidou系统建立电离层模型在高、低纬度等边缘区域精度较低,在中纬度区域精度略低于单模GPS系统；Beidou卫星硬件延迟比较稳定,月平均变化不超过1.8ns。 3.利用GLONASS并址站数据分析伪距频间偏差特性,认为不同卫星的接收机P1P2频间偏差变化稳定,但差异较大,且没有体现与频率有显著的线性关系：鉴于此,本文提出一种顾及频间偏差的多模电离层建模算法,首先估计出全部基准站相对某一测站的频间偏差并修正,再进行电离层建模,该算法可有效提高电离层模型及硬件延迟分离精度。 4.为减少建模过程中造成的精度损失,建立基于单颗卫星的区域精化电离层模型。同时,基于精化电离层产品、宽巷UPD及单差残余硬件延迟产品,提出一种PPP快速收敛算法。利用精化电离层模型产品进行单频PPP解算,在N、E、U三个方向的平均RMS值分别为3.8,4.3和9.2cm；采用快速收敛算法,双频PPP用户的收敛时间显著降低,大约50%的流动站可以在5分钟内收敛到2dm。 5.基于中国陆太网络实时数据流搭建了电离层实时估计服务软件,对实时数据处理中的定权、抗差、硬件延迟处理策略以及背景场的选择等进行探讨；通过与自估产品、CODE事后产品以及流动站反演等多种手段评估,在中高纬度地区实时模型精度可达2-3TECu,低纬度地区略低约为3-4TECu。利用实时电离层产品进行单频SPP、PPP定位,在中高纬度地区,单频SPP的3D偏差优于1.2m,低纬度地区优于2.2m；单频PPP可以达到平面0.2m,高程0.5m的精度；实时电离层产品有效监测了2013年076日磁暴期间中国区域电子密度的变化。
[Abstract]:The ionosphere is an important part of sun earth space environment, understand the structure and activities of the ionosphere, is an important basis for human survival awareness and use of the environment on their own. The ionospheric research in the relationship between on space environment and atmosphere of each layer and for improving the speed, precision positioning, timing, etc. navigation system, has a very important value.
Compared with the traditional ionosphere detection technology, GNSS detection technology can realize continuous operation, high density coverage. Currently, four of global navigation satellite system (Global Navigation Satellite System, GNSS) coexist with the development of the situation has been formed. With the continuous operation of the multi-mode CNSS tracking station increases with the number of observation data and improve the quality, in-depth study according to the different characteristics of the multi-mode GNSS system, carry out the ionospheric modeling system based on multimode GNSS is necessary.
Due to the ionospheric model, pseudo range measurement accuracy and other factors, single point positioning can only obtain decimeter and meter precision. Through different combination of frequencies, frequency users can eliminate the ionospheric error affecting more than 99%. But the combination of observations magnified observation noises, need more time to achieve double PPP convergence. Therefore, to further improve the accuracy of ionospheric model, which can help to improve the positioning accuracy of the single frequency, dual frequency PPP and accelerate the convergence speed.
The ionospheric delay has great influence on the single frequency navigation users, but the real-time correction effect of navigation system itself is limited, it is difficult to obtain the high precision positioning. Therefore, regional or global real-time data tracking station network to provide flow based on a real-time ionospheric model, can effectively improve the positioning accuracy of the single frequency users within the service area at the same time., using real time ionospheric model can achieve high precision monitoring of the ionosphere, contribute to the variation of ionospheric disturbances and irregular.
Aiming at some problems in the two-dimensional ionospheric tomography, data preprocessing, ionospheric extraction methods are analyzed; based Chinese regional ionospheric model GPS/Beidou measurement data analysis system of multimode ionospheric model, hardware delay estimation accuracy; analysis of GLONASS pseudorange frequency deviation, a method is proposed to correct a priori, can to effectively eliminate the pseudo frequency deviation between delayed extraction effect on GLONASS satellite ionosphere; intensive use of regional reference station, a refined ionospheric model of single satellite based on dual frequency PPP presents a fast convergence algorithm based on the refinement of ionospheric products; Chinese regional real-time data stream developed a real-time ionospheric model system, providing products for the real-time ionospheric delay Chinese regional users, can be applied to single frequency positioning and ionospheric Chinese area change monitoring. The main contents of this paper are as follows:
1. according to the observation data in the clock jump, the inter satellite difference MW non difference MW, GF cycle slip detection, clock jump; compared with the phase smoothing pseudo range and combined observations of ionospheric delay decomposition method extraction accuracy; regional ionospheric modeling of Chinese station selection is analyzed, experimental results show that the 60 or so uniform tracking station can obtain higher accuracy of model.
2. data from the Beidou/GPS mode was established Chinese regional ionospheric model. In the current satellite tracking station distribution, establishing the ionospheric model in the high use of single Beidou system, the low latitude edge region with low accuracy, slightly lower than the single mode of GPS system in the mid latitude region precision; Beidou satellite hardware delay is relatively stable, the average monthly change more than 1.8ns.
3. using GLONASS and pseudo distance deviation between the access frequency of station data, P1P2 satellite receiver that different frequency deviation between changes in stability, but the difference is large, and there is no significantly linear relationship between expression and frequency: in view of this, this paper presents a consideration of frequency deviation between multimode ionosphere modeling algorithm, first we estimate all the base station relative to a measuring station and frequency deviation correction of ionospheric modeling, the algorithm can effectively improve the ionospheric model and hardware delay precision of separation.
4. in order to reduce the loss caused by the accuracy of the modeling process, the establishment of a regional ionospheric model refinement of single satellite based on the ionosphere. At the same time, refined products based on the wide lane UPD and single difference delay residual hardware products, this paper puts forward a PPP fast convergence algorithm. By using the refined model of the ionosphere products of single frequency PPP solution in N E RMS U, the average of three directions were 3.8,4.3 and 9.2cm; the fast convergence algorithm, the convergence time of dual frequency PPP users decreased significantly, about 50% of the mobile station can converge to the 2dm. in 5 minutes
5. real time data stream based on network Chinese land too set up service software for real-time estimation of the ionosphere, right, real-time data processing in robust hardware, delay processing strategy and background field selection are discussed; and through self assessment of products, CODE products and a variety of mobile stations after the inversion and other means of assessment, in the high latitudes real-time model precision of 2-3TECu and low latitudes slightly lower about 3-4TECu. using real-time ionospheric products for single frequency SPP, PPP positioning, in the middle and high latitudes, single frequency SPP 3D deviation is better than 1.2m, the low latitude region is better than that of 2.2m; PPP single frequency can reach 0.2m 0.5m plane, elevation accuracy; real-time ionospheric are effective to monitor the change of electron density region China during the 2013 076 storm.

【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：P228.4;P352

【参考文献】