Journal of Global Positioning Systems最新文献_第2页

Performance Evaluation of EGNOS in Challenging Environments 挑战性环境下EGNOS的性能评估

Journal of Global Positioning Systems Pub Date : 2012-12-31 DOI: 10.5081/JGPS.11.2.145

Jingbin Liu, Ruizhi Chen, Yuwei Chen, T. Kroger, L. Pei

{"title":"Performance Evaluation of EGNOS in Challenging Environments","authors":"Jingbin Liu, Ruizhi Chen, Yuwei Chen, T. Kroger, L. Pei","doi":"10.5081/JGPS.11.2.145","DOIUrl":"https://doi.org/10.5081/JGPS.11.2.145","url":null,"abstract":"Space-based augmentation systems (SBAS), such as EGNOS, are largely used to complement GPS for accurate and reliable positioning, which is required by rapidly growing location-based services (LBS). However, it is challenging to use EGNOS in the environments including urban areas and marginal area of the monitoring networks, where many LBS are delivered. Through the experiments in the challenging observation conditions, this study first evaluates the performance of EGNOS in these environments. Challenges consist in two aspects: EGNOS signals may be interrupted by blockages; EGNOS messages are not produced at all for marginal geographical areas due to the lack of raw satellite measurements. In order to use EGNOS for enhanced positioning performance in these environments, this paper then discusses several potential solutions. It is concluded that the two autonomous approaches, i.e. using aged corrections and mixing corrected and uncorrected satellites, can improve the positioning accuracy with a stand-alone receiver, and a full EGNOS positioning performance can be achieved in urban areas via a terrestrial access to EGNOS data, for example, the Internet connection with a smartphone. This paper discusses the effectiveness and usability of these approaches.","PeriodicalId":237555,"journal":{"name":"Journal of Global Positioning Systems","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130905374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 7

An Analysis of Low-Latitude Ionospheric Scintillation and Its Effects on Precise Point Positioning 低纬度电离层闪烁及其对精确点定位的影响分析

Journal of Global Positioning Systems Pub Date : 2012-06-30 DOI: 10.5081/JGPS.11.1.22

R. Xu, Zhizhao Liu, Min Li, Y. Morton, Wu Chen

{"title":"An Analysis of Low-Latitude Ionospheric Scintillation and Its Effects on Precise Point Positioning","authors":"R. Xu, Zhizhao Liu, Min Li, Y. Morton, Wu Chen","doi":"10.5081/JGPS.11.1.22","DOIUrl":"https://doi.org/10.5081/JGPS.11.1.22","url":null,"abstract":"Global Positioning System (GPS) receivers at low latitudes have a high probability of experiencing severe ionospheric scintillations. This paper presents the results of scintillation characteristics and scintillation effect on GPS precise point positioning (PPP), using the data observed by the first ever GNSS scintillation monitoring receiver in Hong Kong. Ionospheric scintillation data were collected in July and August 2012 using a Septentrio PolaRxS Pro receiver located at a station (22°12′N, 114°15′E) in the south of Hong Kong. It was observed that August had much more and stronger scintillations than July in Hong Kong. Amplitude scintillation events ( 4 S ≥0.4) were frequently observed during 21:00-3:00 LT (UT+8 hour) in July and 20:004:00 LT in August. Strong scintillations ( 4 S ≥0.8 or rad 8 . 0    ) were mostly observed during 0:00-1:00 LT in July and 20:00-23:00 LT in August. The effect of scintillations on GPS positioning was evaluated using a dual-frequency PPP method. It revealed that under the impact of severe ionospheric scintillations ( 4 S ≥1.0 and   ≥1.0 rad), the largest PPP error can increase to more than 34 cm in the vertical and more than 20 cm in the horizontal components.","PeriodicalId":237555,"journal":{"name":"Journal of Global Positioning Systems","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129438860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 36

Regression and hypothesis tests for multivariate GNSS state time series 多变量GNSS状态时间序列的回归与假设检验

Journal of Global Positioning Systems Pub Date : 2012-06-30 DOI: 10.5081/JGPS.11.1.33

Yanming Feng

{"title":"Regression and hypothesis tests for multivariate GNSS state time series","authors":"Yanming Feng","doi":"10.5081/JGPS.11.1.33","DOIUrl":"https://doi.org/10.5081/JGPS.11.1.33","url":null,"abstract":"A satellite based observation system can continuously or repeatedly generate a user state vector time series that may contain useful information. One typical example is the collection of International GNSS Services (IGS) station daily and weekly combined solutions. Another example is the epoch-by-epoch kinematic position time series of a receiver derived by a GPS real time kinematic (RTK) technique. Although some multivariate analysis techniques have been adopted to assess the noise characteristics of multivariate state time series, statistic testings are limited to univariate time series. After review of frequently used hypotheses test statistics in univariate analysis of GNSS state time series, the paper presents a number of T-squared multivariate analysis statistics for use in the analysis of multivariate GNSS state time series. These T-squared test statistics have taken the correlation between coordinate components into account, which is neglected in univariate analysis. Numerical analysis was conducted with the multi-year time series of an IGS station to schematically demonstrate the results from the multivariate hypothesis testing in comparison with the univariate hypothesis testing results. The results have demonstrated that, in general, the testing for multivariate mean shifts and outliers tends to reject less data samples than the testing for univariate mean shifts and outliers under the same confidence level. It is noted that neither univariate nor multivariate data analysis methods are intended to replace physical analysis. Instead, these should be treated as complementary statistical methods for a prior or posteriori investigations. Physical analysis is necessary subsequently to refine and interpret the results.","PeriodicalId":237555,"journal":{"name":"Journal of Global Positioning Systems","volume":"463 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124568366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Detecting Severe Weather using GPS Tomography: An Australian Case Study 利用GPS断层扫描探测恶劣天气:一个澳大利亚的案例研究

Journal of Global Positioning Systems Pub Date : 2012-06-30 DOI: 10.5081/JGPS.11.1.59

T. Manning, Kefei Zhang, W. Rohm, S. Choy, F. Hurter

{"title":"Detecting Severe Weather using GPS Tomography: An Australian Case Study","authors":"T. Manning, Kefei Zhang, W. Rohm, S. Choy, F. Hurter","doi":"10.5081/JGPS.11.1.59","DOIUrl":"https://doi.org/10.5081/JGPS.11.1.59","url":null,"abstract":"The dynamics of water vapour (WV) has a strong influence on the formation and lifecycle of severe mesoscale convective storm systems due to the large energy transfers in the hydrological processes. Contrary to its importance WV remains poorly understood and inadequately measured both spatially and temporally, especially in the southern hemisphere where meteorological data are sparse. GPS meteorology is currently one of the most important atmospheric remote sensing instruments for meteorology and climatology due to its high spatial and temporal resolutions. Kalman filtering based GPS tomography is a promising method of reconstructing dynamically changing four dimensional (4D) wet refractivity fields. This method takes advantage of the high density and homogeneity of ground-based GPS Continuously Operating Reference Station (CORS) networks. Ground-based GPS tomography has the potential to utilize the dense groundbased infrastructure in Australia providing wet refractivity field solutions at a high spatial and temporal resolution to improve early detection and prediction of severe weather. This research presents a case study based on the analysis of an extreme convective super cell storm in the Victorian region during March 2010 using GPS tomography and the most advanced state-wide CORS network – GPSnet in Australia. Integrated Precipitable Water Vapour (PWV) estimates derived for the MOBS GPS CORS station confirmed high time resolution as well as sensitivity to incoming severe weather. A wet refractivity index adopted for GPS tomographic wet refractivity profiles shows an excessive increase as a response to supercell thunderstorm formation. Finally a 2D cross section mapping over the lifecycle of this severe weather event concludes a correlation between the highly dynamic spatial and temporal changes of wet refractivity modelled using 4D GPS tomography with precipitation intensities measured using weather radars.","PeriodicalId":237555,"journal":{"name":"Journal of Global Positioning Systems","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126723055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 32

A Floor Plan based Vision Navigation System for Indoor Navigation with Smart Device 基于平面图的智能设备室内视觉导航系统

Journal of Global Positioning Systems Pub Date : 2012-06-30 DOI: 10.5081/JGPS.11.1.71

Bei Huang, Yang Gao

{"title":"A Floor Plan based Vision Navigation System for Indoor Navigation with Smart Device","authors":"Bei Huang, Yang Gao","doi":"10.5081/JGPS.11.1.71","DOIUrl":"https://doi.org/10.5081/JGPS.11.1.71","url":null,"abstract":"Many smart devices like smart phone and tablet nowadays are featured for hybrid sensor platform of GPS chip, inertial sensor(s), magnetic compass and other gadgets such as camera and Wi-Fi. The interest to apply those smart devices for indoor navigation is growing since a large variety of sensors on such devices enable hybrid location solutions to not only improve the availability of indoor positioning but also the accuracy and smoothness. However, in deep indoor scenario, the positioning accuracy is still seldom satisfactory due to large accumulative errors of dead-reckoning sensors. In this paper, a floor plan based vision navigation method is designed for pedestrian handset indoor application. The floor plan for buildings is an easily accessible indoor map with detailed path and room information. It can be matched with the vision measurements from the camera sensor to derive accurate and drift-free positions even in deep indoor environments. The Random Sample Consensus (RANSAC) algorithm is adopted for robust matching between floor plan and camera photo. An iPhone Demo App is developed to evaluate the performance of the designed system and the test results indicate meter-level horizontal accuracy.","PeriodicalId":237555,"journal":{"name":"Journal of Global Positioning Systems","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126960036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

A Novel Real-time Precise Positioning Service System: Global Precise Point Positioning With Regional Augmentation 一种新的实时精确定位服务系统:区域增强的全球精确点定位

Journal of Global Positioning Systems Pub Date : 2012-06-30 DOI: 10.5081/JGPS.11.1.2

M. Ge, J. Douša, Xingxing Li, M. Ramatschi, T. Nischan, J. Wickert

{"title":"A Novel Real-time Precise Positioning Service System: Global Precise Point Positioning With Regional Augmentation","authors":"M. Ge, J. Douša, Xingxing Li, M. Ramatschi, T. Nischan, J. Wickert","doi":"10.5081/JGPS.11.1.2","DOIUrl":"https://doi.org/10.5081/JGPS.11.1.2","url":null,"abstract":"Based on precise real time orbit and clock products from a global network, the standard Precise Point Positioning (PPP) computes user states, which requires a long initialization time in order to obtain a converged solution. Conversely, the Network Real-Time Kinematic (NRTK) positioning requires additional corrections from regional or local dense network for instantaneous ambiguity resolution and state solutions. Both standard PPP and NRTK modes have their own advantages and limitations. A new approach is developed to generate undifferenced corrections in the observation domain from a regional network which can be disseminated station-by-station and applied to user observations for instantaneous ambiguity-fixing. In the proposed service, instantaneous ambiguity resolution is accessible for regions with these observation corrections as regional augmentation information, so that PPP and RTK are integrated into a unified service. The paper presented the approach for generating the undifferenced corrections and the realization of the augmented system in detail. Results from an operational service are introduced as experimental validation.","PeriodicalId":237555,"journal":{"name":"Journal of Global Positioning Systems","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130323336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 47

New Outlier Separability Test and Its Application in GNSS Positioning 新的离群可分性检验及其在GNSS定位中的应用

Journal of Global Positioning Systems Pub Date : 2012-06-30 DOI: 10.5081/JGPS.11.1.46

Jinling Wang, Nathan Knight

引用次数: 29

Investigation of Different Interpolation Models Used in Network-RTK for the Virtual Reference Station Technique 网络rtk虚拟参考站技术中不同插值模型的研究

Journal of Global Positioning Systems Pub Date : 2011-12-30 DOI: 10.5081/JGPS.10.2.136

A. Al-Shaery, Samsung Lim, C. Rizos

{"title":"Investigation of Different Interpolation Models Used in Network-RTK for the Virtual Reference Station Technique","authors":"A. Al-Shaery, Samsung Lim, C. Rizos","doi":"10.5081/JGPS.10.2.136","DOIUrl":"https://doi.org/10.5081/JGPS.10.2.136","url":null,"abstract":"This paper thoroughly investigates several approaches to implementing the GNSS network-based real-time positioning technique, which requires the estimation of atmospheric corrections on an epoch-by-epoch basis for RTK. In this study, a network of Continuously Operating Reference Stations in New South Wales, known as CORSnet-NSW, was utilised to: 1) obtain atmospheric residuals from each reference station, and 2) determine network correction for a rover operating in the area covered by the network using several interpolation methods. Applying the atmospheric corrections obtained by the interpolation methods, “synthetic” measurements at a virtual reference station are generated and then used for rover positioning. Field tests with various masterrover baseline lengths ranging from 21 to 62km indicate that a range of 1.9 to 6.5cm of horizontal positioning accuracy is achieved. In this study, the performance of geostatistical (Oridinary Kriging Method and Least Squares Collocation Method) and deterministic (Linear Combination Method, Linear Interpolation Method, Low-order Surface Method and Multiquadric Surface Fitting Method) interpolation methods used in GNSS network-based RTK positioning were also analysed in order to identify the optimal method for mitigating atmospheric effects for real-time kinematic applications under different network geometries.","PeriodicalId":237555,"journal":{"name":"Journal of Global Positioning Systems","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131195570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 33

GPS Signal Detection Using Hypothesis Testing Analysis 基于假设检验分析的GPS信号检测

Journal of Global Positioning Systems Pub Date : 2011-12-30 DOI: 10.5081/JGPS.10.2.125

Wen Zhang, M. Ghogho

引用次数: 2

Impact of the GNSS Time Offsets on Positioning Reliability GNSS时间偏移对定位可靠性的影响

Journal of Global Positioning Systems Pub Date : 2011-12-30 DOI: 10.5081/JGPS.10.2.165

Jinling Wang, Nathan Knight, Xiaochun Lu

{"title":"Impact of the GNSS Time Offsets on Positioning Reliability","authors":"Jinling Wang, Nathan Knight, Xiaochun Lu","doi":"10.5081/JGPS.10.2.165","DOIUrl":"https://doi.org/10.5081/JGPS.10.2.165","url":null,"abstract":"With the development of GPS, GLONASS, Galileo, Compass, QZSS and the IRNSS, there has been growing interest in the development of system independent receivers. However, one of the problems encountered in system independent receivers is in the different time systems employed by each of the satellite navigation systems. To overcome this problem it has become a standard practice to solve for the time differences within the receiver’s navigation solution via a combination of receiver clock corrections and/or time offsets. While this technique overcomes the problem of the different time systems, it is at the cost of a satellite from each additional time system. Despite this, the numerous studies that combine multiple satellite navigation systems this way have still found that there are significant benefits in improved accuracy, integrity, continuity and availability. To enhance interoperability though satellite navigation system providers are intending to measure and transmit the time offsets to other time systems. The subsequent use of these time offsets will provide a more accurate navigation solution than without them. However, the problem with using the time offsets is that they pose an additional integrity risk because they are also potential sources of faults. However, with the use of the time offsets for multiple constellation solution, a proper Receiver Autonomous Integrity Monitoring method has not been developed. Thus, mathematical models to account for the time differences with and without the time offsets are presented in this paper. Furthermore, the model that incorporates the time offset allows the application of Receiver Autonomous Integrity Monitoring to detect the presence of any faults within the time offsets. The reliability of the linear models is then compared using GPS and GLONASS geometry in terms of the Minimal Detectable Biases, Protection Levels and the correlation coefficients. The results of this analysis indicate that a more reliable solution can be obtained with the time offsets because they are additional measurements.","PeriodicalId":237555,"journal":{"name":"Journal of Global Positioning Systems","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114849310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 36