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Numerical weather modeling-based slant tropospheric delay estimation and its enhancement by GNSS data

Geo-Spatial Information Science 2013年第3期16卷 186-200页

作者： Lei YANG Chris HILL terry moore Nottingham Geospatial Institute The University of NottinghamTriumph RoadNottinghamNG72TUUK

Unmitigated tropospheric delay is one of the major error sources in precise point positioning(PPP).Precise Slant Tropospheric Delay(STD)estimation could help to provide cleaner observables for PPP,and improve its convergence,accuracy,and *** is difficult to model accurately due to the rapid spatial and temporal variation of the water vapor in the *** the traditional approach,the STD is mapped from the zenith direction,which assumes a spherically symmetric local tropospheric profile and has *** this paper,a new approach of directly estimating the STD from high resolution numerical weather modeling(NWM)products is *** approach benefits from the best available meteorological information to improve real time STD estimation,with the RMS residual lower than 3.5 cm above 15°elevation,and 2 cm above 30°.Therefore,the new method can provide sufficient accuracy to improve PPP convergence *** improve the performance of the new method in highly variable tropospheric conditions,a correction scheme is proposed which combines NWM information with multi-GNSS observations from a network of local continuously operating reference *** is demonstrated through a case study that this correction scheme is quite effective in reducing the STD estimation residuals and PPP convergence time.

关键词： slant troposphere delay numerical weather modeling(NWM) precise point positioning(PPP) multi GNSS

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Quality assessment of OpenStreetMap data using trajectory mining

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Geo-Spatial Information Science 2016年第1期19卷 56-68页

作者： Anahid Basiri Mike Jackson Pouria Amirian Amir Pourabdollah Monika Sester Adam Winstanley terry moore Lijuan Zhang The Nottingham Geospatial Institute The University of NottinghamNottinghamUK Ordnance Survey SouthamptonUK The School of Computer Science The University of NottinghamNottinghamUK Institute of Cartography and Geoinformatics(IKG) Leibniz UniversitätHannoverGermany e Department of Computer Science Maynooth UniversityMaynoothIreland Faculty of Civil and Environmental Engineering The Technion-Israel Institute of TechnologyHaifaIsrael

OpenStreetMap(OSM)data are widely used but their reliability is still *** contributors to OSM have not been trained in geography or surveying and consequently their contributions,including geometry and attribute data inserts,deletions,and updates,can be inaccurate,incomplete,inconsistent,or *** are some mechanisms and applications dedicated to discovering bugs and errors in OSM *** systems can remove errors through user-checks and applying predefined rules but they need an extra control process to check the real-world validity of suspected errors and *** paper focuses on finding bugs and errors based on patterns and rules extracted from the tracking data of *** underlying idea is that certain characteristics of user trajectories are directly linked to the type of *** such rules,some sets of potential bugs and errors can be identified and stored for further investigations.

关键词： Spatial data quality OpenStreetMap(OSM) trajectory data mining

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Integrity monitoring of fixed ambiguity Precise Point Positioning(PPP)solutions

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Geo-Spatial Information Science 2013年第3期16卷 141-148页

作者： Altti JOKINEN Shaojun FENG Wolfgang SCHUSTER Washington OCHIENG Chris HIDE terry moore Chris HILL Department of Civil and Environmental Engineering Imperial College London Centre for Transport StudiesLondon SW72AZUK Nottingham Geospatial Institute(NGI) University of NottinghamNottingham NG72TUUK

Traditional positioning methods,such as conventional Real Time Kinematic(cRTK)rely upon local reference networks to enable users to achieve high-accuracy *** need for such relatively dense networks has significant cost *** Point Positioning(PPP)on the other hand is a positioning method capable of centimeter-level positioning without the need for such local networks,hence providing significant cost benefits especially in remote *** paper presents the state-of-the-art PPP method using both GPS and GLONASS measurements to estimate the float position solution before attempting to resolve GPS integer *** monitoring is carried out using the Imperial College Carrier-phase Receiver Autonomous Integrity Monitoring method.A new method to detect and exclude GPS base-satellite failures is developed.A base-satellite is a satellite whose measurements are differenced from other satellite’s measurements when using between-satellite-differenced measurements to estimate *** failure detection and exclusion methods are tested using static GNSS data recorded by International GNSS Service stations both in static and dynamic processing *** results show that failure detection can be achieved in all cases tested and failure exclusion can be achieved for static *** the kinematic processing cases,failure exclusion is more difficult because the higher noise in the measurement residuals increases the difficulty to distinguish between failures associated with the base-satellite and other satellites.

关键词： Precise Point Positioning(PPP) integrity ambiguity resolution failure exclusion

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Comparison of Numerical Weather Models in Estimating the GNSS Signals Slant Tropospheric Delay

Comparison of Numerical Weather Models in Estimating the GNS...

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第四届中国卫星导航学术年会

作者： Lei Yang Chris Hill Chris Hide terry moore Nottingham Geospatial Institute University of Nottingham

For high accuracy Global Navigation Satellite Systems （GNSS） positioning, such as Precise Point Positioning （PPP）, the troposphere delay remains one of the major error sources. The PPP convergence time and vertical positioning accuracy are influenced by the applied tropospheric model and mapping function. Due to the lack of real time atmosphere information, the accuracies of both the model and mapping function are limited. In the past decades, Numerical Weather Modelling （NWM） has experienced a period of rapid development. With the support of high performance supercomputers, NWM uses a 3D grid model to describe or forecast the atmospheric physical conditions, such as pressure, temperature, humidity, etc. These information could enable high accuracy direct estimation of the slant tropospheric delay （STD）. In contrast to the traditional mapping function approach, direct estimation on individual STDs can avoid the assumption that the site local weather condition is a balanced profile, thus the troposphere delays are estimated on both signal elevation and azimuth. This paper will review the technique of NWM based direct STD estimation, and investigate its resolution requirement as well as the real time applicability. Various products from the Unified Model （UM）, provided by the United Kingdom Met Office, is used in this study. In the resolution test, the troposphere delay estimation based on the UM North Atlantic and European （NAE） regional product （12-km horizontal resolution） is compared with estimation based on the UM global product （40-km horizontal resolution）. The high resolution product could provide a better estimation accuracy, but with the cost of a larger data volume. This test is aiming to initially investigate the estimation accuracy from different atmospheric information resolutions. In the real time applicability test, the troposphere delay estimation based on the UM forecast field product is compared with estimation based on the analyzed field. Although

关键词： GNSS Tropospheric Delay NWM PPP

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Particle Filtering in Collaborative Indoor Positioning

Particle Filtering in Collaborative Indoor Positioning

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第四届中国卫星导航学术年会

作者： Hao Jing Chris Hide Chris Hill terry moore Nottingham Geospatial Institute University Of Nottingham

Satellite positioning accuracy cannot meet the required needs due to lack of GPS signals inside buildings. Wi-Fi fingerprinting has become a popular method of overcoming problems in indoor positioning and navigation. Yet the accuracy of fingerprinting is rather limited and the system is prone to the changesof the building structure and Wi-Fi networks. However, if mobile users canshare their signal as well as ranging and positioning information collaboratively to form a local network, the information could be used to correct failures in the fingerprinting process and provide more signal and information to derive robust positioning results. This paper implements collaborative positioning using Particle Filters which give the potential of utilizing additional positioning information whenever possible. The filter takes into account the uncertainty of indoor positioning results. Therefore it provides a series of possible solutions and outputs the most likely result. Simulation tests are carried out to evaluate the performance of the proposed algorithm. Results are analysed and improvement in accuracy could be seen in the results.

关键词： Particles Filters Collaborative Indoor Positioning Wireless Network

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Innovative Atmosphere Effect Mitigation Using New GNSS Signals

Innovative Atmosphere Effect Mitigation Using New GNSS Signa...

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第二届中国卫星导航学术年会

作者： Zeynep Elmas Chris Hill Marcio Aquino terry moore InstitLlte of Engineering Surveying and Space Geodesy University of NottinghamNottinghamUK NG7 2TU

＜正＞New signals from the modernised satellite navigation systems（GPS and GLONASS） and the developing systems（COMPASS and GALILEO） will present opportunities for more accurate and reliable positioning *** exploitation of these new signals will also enable the development of markets and applications for difficult environments,which may not suit the current Global Navigation Satellite System （GNSS） *** research presented in this paper is aiming to exploit the improvement in monitoring, modelling and mitigating the atmospheric effects,with the appearance of the new signals and *** results will provide a potential supplement to high accuracy positioning techniques,such as RTK and PPP Both the troposphere and ionosphere effects are studied in this *** terms of the troposphere effect,it is mitigated/solved in RTK and PPP via different *** of these methods takes the horizontal distribution of troposphere delay into consideration,this is mainly due to the high temporal and spatial variability of water vapour in the troposphere,which is difficult to interpolate or model *** increased number of satellites observable,a better investigation of the troposphere wet delay horizontal distribution could be attempted. If the measurements from a network of CORS stations are dense enough,a near real time horizontal troposphere delay correction for the network area could be *** could then be used as a supplement to either the interpolation procedure in Network RTK or the mapping function procedure in PPP,improving both the accuracy and the convergence *** preliminary generation algorithm of this horizontal troposphere delay correction is introduced in this paper. As for the ionospheric effects,the GNSS modernization provides an opportunity to study the higher（second and third） order ionospheric range errors and scintillation effects（abrupt power fades and phase variations in received signals）.The way the new s

关键词： New GNSS signals Atmosphere mitigation

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采用无线信号测距加权的室内协同定位

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导航定位学报 2014年第2期2卷 31-39页

作者：荆昊 James PINCHIN Chris HILL terry moore 英国诺丁汉大学地理空间研究所

随着基于位置服务应用的普及,室内外无缝定位已成为下一代定位系统的核心,但是精确的室内定位至今仍是难点问题。众多学者提出过无线信号定位算法,然而无线信号具有不稳定性,且需要事先建立信号特征指纹数据库,这给定位带来了误差和繁... 详细信息

随着基于位置服务应用的普及,室内外无缝定位已成为下一代定位系统的核心,但是精确的室内定位至今仍是难点问题。众多学者提出过无线信号定位算法,然而无线信号具有不稳定性,且需要事先建立信号特征指纹数据库,这给定位带来了误差和繁琐性。通过对室内环境中超宽带信号测距结果分析以及对快速生成无线信号数据库方法的探讨,提出一种基于多用户测距约束的融合多传感器信息的协同室内定位算法。该算法利用粒子滤波集成了航向推算数据、WiFi数据、用户间测距以及室内地图等信息。测距约束能够剔除由于信号不稳定或数据库没有及时更新造成的误差。通过集成室内采集的数据,验证了该算法能够有效提高室内定位精度及稳定性。结果表明该算法比航向推算或WiFi定位结果提高了40%以上。

关键词：协同测距室内定位 WiFi指纹数据库粒子滤波

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