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On the consideration of combined measurement uncertainties in relation to GUM concepts in adjustment computations 平差计算中与GUM概念相关的组合测量不确定度的考虑
IF 1.4 Q4 REMOTE SENSING Pub Date : 2022-02-05 DOI: 10.1515/jag-2021-0043
F. Neitzel, M. Lösler, R. Lehmann
Abstract In this contribution it is shown how an extended uncertainty budget of the observations according to the Guide to the Expression of Uncertainty in Measurement (GUM) can be considered in adjustment computations. The extended uncertainty budget results from the combination of Type A standard uncertainties determined with statistical methods and Type B standard uncertainties derived with nonstatistical methods. Two solutions are investigated, namely the adjustment in the classical Gauss-Markov model and the adjustment in the Gauss-Markov model using Monte Carlo simulations for the consideration of the uncertainties of the observations. Numerical examples are given to show that an appropriate interpretation of the dispersion measures for the unknowns is particularly important in order to avoid misinterpretation of the results. Furthermore, the effects of changing the weights of the observations on the adjustment results are shown. Finally, practical advice for the consideration of an extended uncertainty budget of the observations in adjustment computations is given.
摘要在这篇文章中,我们展示了如何在平差计算中考虑根据《测量不确定度表达指南》(GUM)对观测结果的扩展不确定度预算。扩展的不确定度预算是由统计方法确定的A类标准不确定度和非统计方法得出的B类标准不确定性的组合产生的。研究了两种解决方案,即经典高斯-马尔可夫模型中的调整和使用蒙特卡罗模拟考虑观测不确定性的高斯-马尔可夫模式中的调整。给出的数值例子表明,为了避免对结果的误解,对未知量的离散测度进行适当的解释尤为重要。此外,还显示了改变观测值权重对平差结果的影响。最后,给出了在平差计算中考虑观测的扩展不确定性预算的实用建议。
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引用次数: 3
Evaluation of QZSS orbit and clock products for real-time positioning applications 用于实时定位应用的QZSS轨道和时钟产品的评估
IF 1.4 Q4 REMOTE SENSING Pub Date : 2022-02-03 DOI: 10.1515/jag-2021-0064
B. Bramanto, I. Gumilar
Abstract The Quasi-Zenith Satellite System (QZSS) is the recent Japanese satellite positioning system to enhance the positioning accuracy in Japan’s urban areas. Additionally, they provide precise orbit and clock corrections and can be obtained through their experimental signals (LEX), streaming access, and published site. Multi-GNSS Advanced Demonstration tool for Orbit and Clock Analysis (MADOCA) is one of the precise products offered in QZSS services that can be obtained on a global scale. In this study, we evaluated the performance of MADOCA orbit and clock corrections, particularly for real-time positioning applications using LEX signals. Based on the simulation, we predict that 16 countries in the East Asia and Oceania regions will gain the maximum benefit of the LEX signals. However, we stress that one may have difficulties decoding the LEX signals at regions where only one QZSS satellite is observed. During our sailing expedition at Sumatran Sea, we could only decode up to 37 % LEX signals for the observation period. It profoundly increased up to 95 % at Sulawesi Strait where at least three QZSS satellites with an elevation angle of, at its minimum, 40° were observed. The orbit and clock accuracy is estimated to be 5.2 cm and 0.6 ns with respect to International GNSS Service (IGS) final products. Our simulation of using the Real-Time Precise Point Positioning (RTPPP) method revealed that the accuracy of the corresponding positioning applications was less than one decimeter. Further, we compared the MADOCA products for RTPPP applications with Apex5 positioning solutions in static field observations. The positioning accuracy for MADOCA-RTPPP during the field observations was estimated to be centimeter to decimeter level and is slightly worse than Apex5 positioning solutions. Nevertheless, we highlight vast positioning applications using MADOCA-RTPPP, e. g., survey and mapping, smart agriculture, and offshore engineering navigation.
准天顶卫星定位系统(Quasi-Zenith Satellite System, QZSS)是日本最近为提高日本城市定位精度而推出的卫星定位系统。此外,它们提供精确的轨道和时钟校正,可以通过它们的实验信号(LEX)、流访问和发布站点获得。多gnss轨道和时钟分析高级演示工具(MADOCA)是QZSS服务中提供的精确产品之一,可以在全球范围内获得。在本研究中,我们评估了MADOCA轨道和时钟校正的性能,特别是在使用LEX信号的实时定位应用中。在此基础上,我们预测东亚和大洋洲地区的16个国家将获得LEX信号的最大效益。然而,我们强调,在只观测到一颗QZSS卫星的地区,解码LEX信号可能会遇到困难。在我们在苏门答腊海的航海考察期间,我们只能解码高达37%的LEX信号。在苏拉威西海峡,至少观测到三颗QZSS卫星,仰角最小为40°,其高度增加了95%。相对于国际GNSS服务(IGS)的最终产品,轨道和时钟精度估计为5.2厘米和0.6纳秒。我们使用实时精确点定位(RTPPP)方法进行的仿真表明,相应的定位应用精度小于1分米。此外,我们将用于RTPPP应用的MADOCA产品与静态现场观测的Apex5定位解决方案进行了比较。MADOCA-RTPPP在野外观测中的定位精度估计在厘米到分米水平,略低于Apex5定位方案。然而,我们强调了使用MADOCA-RTPPP的大量定位应用,例如。测绘、智慧农业、海洋工程导航等。
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引用次数: 2
Geometric quality control for bio-based building elements: Study case segmented experimental shell 生物基建筑元素的几何质量控制:研究案例分割实验壳
IF 1.4 Q4 REMOTE SENSING Pub Date : 2022-01-28 DOI: 10.1515/jag-2020-0035
Gabriel Kerekes, Jan Petrš, V. Schwieger, H. Dahy
Abstract This contribution presents the prerequisites in the construction process of a bio-based experimental pavilion. A first challenge, is to define tolerances and implicitly measurement tolerances for these materials. After defining them, the focus is set on what can be achieved if geometric quality control is only conducted during the assembly process. Despite using high-end total stations and terrestrial laser scanners in this process, the final pavilion showed discrepancies to its model. In some cases, these were larger than the given tolerances, showing on one side what tasks can be achieved with these instruments and on the other, drawbacks that remain a challenge in bio-based segmented experimental buildings. Finally, an improved workflow is suggested.
摘要本文介绍了生物实验馆建设过程中的先决条件。第一个挑战是定义这些材料的公差和隐含的测量公差。在定义它们之后,重点是如果仅在装配过程中进行几何质量控制,可以实现什么。尽管在这个过程中使用了高端全站仪和地面激光扫描仪,但最终的展馆与其模型存在差异。在某些情况下,这些仪器大于给定的公差,一方面显示了使用这些仪器可以完成哪些任务,另一方面,这些缺点在基于生物的分段实验建筑中仍然是一个挑战。最后,提出了一种改进的工作流。
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引用次数: 2
Effect of PCV and attitude on the precise orbit determination of Jason-3 satellite PCV和姿态对Jason-3卫星精确定轨的影响
IF 1.4 Q4 REMOTE SENSING Pub Date : 2022-01-26 DOI: 10.1515/jag-2021-0052
Kai Li, Xuhua Zhou, Nannan Guo, Shanshi Zhou
Abstract Satellite attitude modes and antenna phase center variations have a great influence on the Precise Orbit Determination (POD) of Low Earth Orbit satellites (LEOs). Inaccurate information about spacecraft attitude, phase center offsets and variations in the POD leads to orbital error. The Jason-3 satellite experienced complex attitude modes which are fixed, sinusoidal, ramp-up/down and yaw-flip. Therefore, it is necessary to properly construct the attitude model in the process of POD especially when there is no external attitude data. For the antenna phase center correction, the PCO which is the deviation between Antenna Reference Point (ARP) and Mean Antenna Phase Center (MAPC) usually can be calibrated on the ground accurately, but the PCV which is the deviation between Instantaneous Antenna Phase Center (IAPC) and Mean Antenna Phase Center (MAPC) will change greatly with the change of space environment. Residual approach can be used to estimate the receiver PCV map. In this paper, we collected the on-board GPS data of Jason-3 satellite from January 2019 and analyzed the impacts of PCV and spacecraft attitude on the orbit accuracy by performing the reduced-dynamic POD. Compared with the reference orbit released by the Centre National d’Études Spatiales (CNES), using the PCV map can reduce the Root Mean Square (RMS) of orbit differences in the Radial (R), Along-track (T), Cross-track (N) and 3D direction about 0.3, 1.0, 0.9, and 1.4 mm. Based on the estimated PCV map, the orbit accuracy in R, T, N and 3D direction is 1.24, 2.81, 1.17, and 3.29 cm respectively by using the measured attitude data. When using the attitude model, the orbit accuracy in R, T, N and 3D directions is 1.60, 3.54, 1.33, and 4.13 cm, respectively. The results showed that the combination of measured attitude data and modeled PCV map can obtain the better orbit solution. It is essential to build a corresponding model in high-precision orbit determination, when there is no attitude data and PCV map.
卫星姿态模式和天线相位中心变化对近地轨道卫星的精确定轨(POD)有很大影响。关于航天器姿态、相位中心偏移和POD变化的不准确信息会导致轨道误差。Jason-3卫星经历了固定、正弦、上升/下降和偏航翻转的复杂姿态模式。因此,在POD过程中,特别是在没有外部姿态数据的情况下,有必要合理构建姿态模型。对于天线相位中心校正,通常可以在地面精确校准天线参考点(ARP)与平均天线相位中心(MAPC)之间的偏差PCO,但瞬时天线相位中心(IAPC)与平均天线相位中心(MAPC)之间的偏差PCV会随着空间环境的变化而发生较大变化。残差法可用于估计接收机的PCV图。本文采集了Jason-3卫星2019年1月的星载GPS数据,通过减动态POD分析了PCV和航天器姿态对轨道精度的影响。与中国国家空间研究中心(CNES)发布的参考轨道相比,利用PCV图可将径向(R)、顺轨道(T)、交叉轨道(N)和三维方向的轨道差的均方根(RMS)分别减小0.3、1.0、0.9和1.4 mm左右。基于估计的PCV图,利用实测姿态数据,在R、T、N和3D方向上的轨道精度分别为1.24、2.81、1.17和3.29 cm。使用姿态模型时,R、T、N和3D方向的轨道精度分别为1.60、3.54、1.33和4.13 cm。结果表明,将实测姿态数据与模型化的PCV图相结合可以得到较好的轨道解。在没有姿态数据和PCV图的情况下,高精度定轨需要建立相应的模型。
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引用次数: 3
Recent GPS-based long wavelength crustal deformation revealed active postseismic deformation due to the 2006 Yogyakarta earthquake 最近基于GPS的长波地壳变形揭示了2006年日惹地震引起的活跃的震后变形
IF 1.4 Q4 REMOTE SENSING Pub Date : 2022-01-26 DOI: 10.1515/jag-2020-0053
C. Pratama, L. Heliani, N. Widjajanti, E. Gunawan, I. M. Anjasmara, Suci Novianti, Tika Widya Sari, Retno Eka Yuni, Adelia Sekarsari
Abstract We analyze the Global Positioning System (GPS)-derived strain rate distribution to investigate active crustal structure in Central Java, Indonesia, using ten years (2010–2019) continuous and permanent observation data. Central Java is the third-most populous province in Indonesia where postseismic deformation of devastating Yogyakarta earthquake in 2006 might influence the GPS data. The postseismic extensional response might overshadow the low contractional process due to active tectonics deformation. A decomposition method of a calculated strain rate shows a long wavelength feature with the extensional region in the vicinity of the 2006 Yogyakarta earthquake may reflect the postseismic process remain active. The short wavelength pattern is sharpening potential active tectonics dominated by oblique Northwest-Southeast dip-slip motion with East-West left-lateral sense. Our result demonstrates essential implications for assessing future seismic hazard potential within a low strain rate such as the Central Java region.
摘要我们使用十年(2010-2019)的连续和永久观测数据,分析了全球定位系统(GPS)导出的应变速率分布,以研究印度尼西亚中爪哇的活动地壳结构。中爪哇省是印度尼西亚人口第三多的省份,2006年日惹毁灭性地震的震后变形可能会影响GPS数据。由于活跃的构造变形,地震后的伸展反应可能掩盖了低收缩过程。计算应变率的分解方法显示出长波长特征,2006年日惹地震附近的伸展区域可能反映了地震后过程仍然活跃。短波长模式使以东西向左旋倾斜的西北-东南倾滑运动为主的潜在活动构造更加尖锐。我们的结果证明了在低应变速率(如中爪哇地区)内评估未来地震灾害潜力的重要意义。
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引用次数: 0
GNSS time and frequency transfers through national positioning, navigation and timing infrastructure 通过国家定位、导航和授时基础设施进行全球导航卫星系统时间和频率传输
IF 1.4 Q4 REMOTE SENSING Pub Date : 2021-12-24 DOI: 10.1515/jag-2021-0061
Thayathip Thongtan, Sivinee Sawatdiaree, C. Satirapod
Abstract GNSS signals have been a practical time transfer tool to realise a Coordinated Universal Time (UTC) and set civilian clocks around the world with respect to this atomic time standard. UTC time scale is maintained by the International Bureau of Weights and Measurements (BIPM) adjusted to be close to a time scale based on the Earth’s rotation. In Thailand, the official atomic time clocks are maintained by the National Institute of Metrology Thailand (NIMT) to produce UTC(NIMT) and Thailand standard time which is always 7 hours ahead of UTC(NIMT) because of the time zone differences between Greenwich and Bangkok. National Positioning, Navigation and Timing (PNT) infrastructure comprises of GNSS geodetic receivers uniformly distributed to continually observe GNSS signals, mainly for geodetic survey applications both real-time and post-processing services. NIMT is involved in order to provide time link to UTC and to determine the characteristics of GNSS receiver internal clocks; namely, fractional frequency offset and frequency stabilities by applying the GNSS time transfer techniques of common-view algorithms. Monitored time differences with respect to UTC(NIMT) are achieved from selected 4 ground stations in different parts of the country with observations of 21 days in order to determine the frequency stability at 1-day and 7-day modes. GNSS standard log files; in RINEX format, at these receivers are transformed into a time transfer standard format; CGGTTS, used to compute the time differences between two stations, the fractional frequency offset and the frequency stability. Averaged fractional frequency offsets are 2.8 × 10 − 13 Hertz/Hertz2.8times {10^{-13}}hspace{2.38387pt}text{Hertz/Hertz} and computed Allan deviation is around 1.5 × 10 − 13 Hertz/Hertz1.5times {10^{-13}}hspace{2.38387pt}text{Hertz/Hertz} for an averaging time of 1 day. The comparison of the national time scale and receiver clock offsets of every receivers in this national GNSS PNT infrastructure could be accomplished through common-view time transfer using GNSS satellites to maintain the time link of geodetic active control points to UTC as well as to determine receiver internal clock characteristics.
摘要GNSS信号已成为实现协调世界时(UTC)的实用时间传输工具,并根据这一原子时间标准在世界各地设置民用时钟。UTC时标由国际度量衡局(BIPM)维护,调整为接近基于地球自转的时标。在泰国,官方原子钟由泰国国家计量研究所(NIMT)维护,以产生UTC(NIMT)和泰国标准时间,由于格林威治和曼谷之间的时区差异,该时间总是比UTC(NIMT)提前7小时。国家定位、导航和授时基础设施由全球导航卫星系统大地测量接收器组成,这些接收器均匀分布,用于持续观测全球导航卫星系信号,主要用于实时和后处理服务的大地测量应用。参与NIMT是为了提供与UTC的时间链接,并确定GNSS接收器内部时钟的特性;即分数频率偏移和频率稳定性。通过对该国不同地区选定的4个地面站进行21天的观测,实现了UTC(NIMT)的监测时差,以确定1天和7天模式下的频率稳定性。全球导航卫星系统标准日志文件;在RINEX格式中,在这些接收器处被转换成时间传输标准格式;CGGTTS,用于计算两个站点之间的时间差、分数频率偏移和频率稳定性。平均分数频率偏移为2.8×10−13赫兹/Hertz2.8次{10^{-13}}space{2.38387pt}text{赫兹/赫兹},计算出的Allan偏差约为1.5×10−13Hertz 1.5次{10 ^{-13} hspace{2.38367pt}text{赫兹/赫兹},平均时间为1天。该国家GNSS PNT基础设施中每个接收器的国家时间尺度和接收器时钟偏移的比较可以通过使用GNSS卫星的共视时间传输来实现,以保持大地测量主动控制点到UTC的时间链路,并确定接收器内部时钟特性。
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引用次数: 3
Linear discontinuous ground deformation detection based on coherence analysis of pre and post event radar image pairs 基于事件前后雷达图像对相干性分析的线性不连续地面变形检测
IF 1.4 Q4 REMOTE SENSING Pub Date : 2021-12-24 DOI: 10.1515/jag-2021-0036
Bartosz Apanowicz
Abstract The article presents information on how to use satellite interferometry to detect linear discontinuous ground deformation [LDGD] caused by underground mining. Assumptions were made based on the properties of the SAR signal correlation coefficient (coherence). Places of LDGD have been identified based on these assumptions. Changes taking place on the surface between two acquisitions lead to worse correlation between two radar images. This results in lower values of the SAR signal correlation coefficient in the coherence maps. Therefore, it was assumed that the formation of LDGD could reduce the coherence value compared to the previous state. The second assumption was an increase in the standard deviation of coherence, which is a classic measurement of variability. Therefore any changes in the surface should lead to increasing standard deviation of coherence compared to the previous state. Images from the Sentinel-1 satellite and provided by the ESA were used for analysis. The research is presented on the basis of two research areas located in the Upper Silesian Coal Basin in the south of Poland. The area in which LDGD could occur was limited to 6 % of the total area in case 1 and 36 % in case 2 by applying an appropriate methodology of satellite image coherence analysis. This paper is an introduction to the development of a method of detecting LDGDs caused by underground mining and to study these issues further.
摘要本文介绍了利用卫星干涉测量技术检测地下开采引起的地表线性不连续变形的方法。根据SAR信号相关系数(相干性)的特性进行了假设。根据这些假设,已经确定了LDGD的地点。两次捕获之间地表发生的变化导致两幅雷达图像之间的相关性变差。这导致相干图中SAR信号相关系数值较低。因此,我们假设LDGD的形成相对于之前的状态会降低相干值。第二个假设是相干性的标准偏差增加,这是衡量可变性的经典方法。因此,表面的任何变化都应该导致相干性的标准偏差比先前的状态增加。欧空局提供的来自哨兵1号卫星的图像被用于分析。该研究是在位于波兰南部上西里西亚煤盆地的两个研究区域的基础上提出的。通过应用适当的卫星图像相干性分析方法,将情况1中可能发生LDGD的区域限制在总面积的6%,在情况2中限制在36%。本文介绍了一种探测地下开采引起的地表塌陷的方法的发展,并对这些问题进行了进一步的研究。
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引用次数: 0
Frontmatter Frontmatter
IF 1.4 Q4 REMOTE SENSING Pub Date : 2021-12-22 DOI: 10.1515/jag-2022-frontmatter1
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引用次数: 0
Target-based terrestrial laser scan registration extended by target orientation 基于目标定向扩展的地面激光扫描配准
IF 1.4 Q4 REMOTE SENSING Pub Date : 2021-12-02 DOI: 10.1515/jag-2020-0030
Jannik Janßen, H. Kuhlmann, C. Holst
Abstract In almost all projects, in which terrestrial laser scanning is used, the scans must be registered after the data acquisition. Despite more and more new and automated methods for registration, the classical target-based registration is still one of the standard procedures. The advantages are obvious: independence from the scan object, the geometric configuration can often be influenced and registration results are easy to interpret. When plane black-and-white targets are used, the algorithm for estimating the target center fits a plane through the scan of a target, anyway. This information about the plane orientation has remained unused so far. Hence, including this information in the registration does not require any additional effort in the scanning process. In this paper, we extend the target-based registration by the plane orientation. We describe the required methodology, analyze the benefits in terms of precision and reliability and discuss in which cases the extension is useful and brings a relevant advantage. Based on simulations and two case studies we find out that especially for registrations with bad geometric configurations the extension brings a big advantage. The extension enables registrations that are much more precise. These are also visible on the registered point clouds. Thus, only a methodological change in the target-based registration improves its results.
摘要在几乎所有使用地面激光扫描的项目中,扫描必须在数据采集后进行登记。尽管有越来越多的新的和自动化的注册方法,但经典的基于目标的注册仍然是标准程序之一。优点是显而易见的:独立于扫描对象,几何配置经常会受到影响,配准结果易于解释。当使用平面黑白目标时,估计目标中心的算法通过扫描目标来拟合平面。到目前为止,有关平面方向的这些信息尚未使用。因此,在登记中包括该信息不需要在扫描过程中付出任何额外的努力。在本文中,我们通过平面定向扩展了基于目标的配准。我们描述了所需的方法,分析了精度和可靠性方面的优势,并讨论了在哪些情况下扩展是有用的,并带来了相关的优势。基于仿真和两个案例研究,我们发现,特别是对于几何配置不好的注册,扩展带来了很大的优势。该扩展使注册更加精确。这些在已注册的点云上也可见。因此,只有在基于目标的注册中进行方法上的改变才能改善其结果。
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引用次数: 7
Validating the impact of various ionosphere correction on mid to long baselines and point positioning using GPS dual-frequency receivers 验证各种电离层校正对GPS双频接收机中长基线和点定位的影响
IF 1.4 Q4 REMOTE SENSING Pub Date : 2021-11-27 DOI: 10.1515/jag-2021-0040
Alaa A. Elghazouly, M. Doma, A. Sedeek
Abstract Due to the ionosphere delay, which has become the dominant GPS error source, it is crucial to remove the ionospheric effect before estimating point coordinates. Therefore, different agencies started to generate daily Global Ionosphere Maps (GIMs); the Vertical Total Electron Content (VTEC) values represented in GIMs produced by several providers can be used to remove the ionosphere error from observations. In this research, an analysis will be carried with three sources for VTEC maps produced by the Center for Orbit Determination in Europe (CODE), Regional TEC Mapping (RTM), and the International Reference Ionosphere (IRI). The evaluation is focused on the effects of a specific ionosphere GIM correction on the precise point positioning (PPP) solutions. Two networks were considered. The first network consists of seven Global Navigation Satellite Systems (GNSS) receivers from (IGS) global stations. The selected test days are six days, three of them quiet, and three other days are stormy to check the influence of geomagnetic storms on relative kinematic positioning solutions. The second network is a regional network in Egypt. The results show that the calculated coordinates using the three VTEC map sources are far from each other on stormy days rather than on quiet days. Also, the standard deviation values are large on stormy days compared to those on quiet days. Using CODE and RTM IONEX file produces the most precise coordinates after that the values of IRI. The elimination of ionospheric biases over the estimated lengths of many baselines up to 1000 km has resulted in positive findings, which show the feasibility of the suggested assessment procedure.
摘要由于电离层延迟已成为GPS的主要误差源,在估计点坐标之前,消除电离层效应至关重要。因此,不同的机构开始每天生成全球电离层地图;由几个提供商产生的以GIM表示的垂直总电子含量(VTEC)值可以用于从观测中去除电离层误差。在这项研究中,将对欧洲轨道确定中心(CODE)、区域TEC地图(RTM)和国际参考电离层(IRI)制作的VTEC地图的三个来源进行分析。评估的重点是特定电离层GIM校正对精确点定位(PPP)解决方案的影响。考虑了两个网络。第一个网络由来自IGS全球站的七个全球导航卫星系统接收器组成。选定的测试日为六天,其中三天是安静的,另外三天是暴风雨,以检查地磁风暴对相对运动学定位解决方案的影响。第二个网络是埃及的一个区域网络。结果表明,使用三个VTEC地图源计算的坐标在暴风雨天比在平静天相差很远。此外,与平静日相比,暴风雨日的标准偏差值较大。使用CODE和RTM IONEX文件生成最精确的坐标,然后生成IRI的值。消除许多基线估计长度高达1000的电离层偏差 km得出了积极的结果,这表明了所建议的评估程序的可行性。
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引用次数: 1
期刊
Journal of Applied Geodesy
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