Analysis Of Global Positioning System Data Research Articles

Outlier elimination method of GPS data points based on Hough transform

The electronic map of railway track can realize the monitoring and evaluation of line status, so as to reduce the workload of manual operation. In order to improve the fitting accuracy of the existing railway track electronic map, the measured data of the railway line are obtained by Global Positioning System (GPS), and the Gaussian coordinates of the measured data points are obtained through coordinate transformation. Based on the analysis of GPS data, the Hough transform is improved to eliminate the outliers in the straight track and curved track scenarios respectively. With the help of the idea of taking the average value of multiple measurements to eliminate errors, the processed data are corrected and the track line is fitted. The results show that the track route electronic map generated by the outlier elimination method based on Hough transform has high accuracy and has important practical significance and practical application value.

Migration Mapper: Identifying movement corridors and seasonal ranges for large mammal conservation

Abstract Modern tracking technology has facilitated a novel understanding of terrestrial mammal movement while revealing that movements are being truncated and lost. The first step towards conserving mobile animals is identifying movement corridors and key seasonal ranges. Yet, the identification and subsequent mapping of these important areas has remained a challenge due to the analytical skills necessary to conduct such analyses. Migration Mapper (MM) is a user‐friendly software that provides tools to analyse global positioning system (GPS) collar data to create season‐specific, population‐level polygons representing areas where most of a population moves (i.e. movement corridors) and areas where most of a population spends time (e.g. high‐use areas, seasonal ranges). MM consists of six standalone modules including data cleaning and review, seasonal movement delineation, movement model application, calculation of population‐level outputs and visualization of results. Analysis of GPS data using MM can provide the spatial polygons necessary to facilitate conservation and policy planning. New initiatives at the local and global levels are already beginning to use MM to facilitate conservation of large, terrestrial mammals.

Individual level spatial-temporal modelling of exposure potential of livestock in the Cove Wash watershed, Arizona

ABSTRACT Personal exposure studies suffer from uncertainty issues, largely stemming from individual behaviour uncertainties. Built on spatial-temporal exposure analysis and methods, this study proposed a novel approach to spatial-temporal modelling that incorporated behaviour classifications taking into account uncertainties, to estimate individual livestock exposure potential. The new approach was applied in a community-based research project with a Tribal community in the southwest United States to address questions on potential livestock exposure to abandoned uranium mines (AUMs). The study aimed to 1) classify Global Positioning System (GPS) data from livestock into three behaviour subgroups – grazing, travelling or resting; 2) calculate the daily cumulative exposure potential for livestock; 3) assess the performance of the computational method with and without behaviour classifications. Using Lotek Litetrack GPS collars, we collected data at a 20-min-interval for two flocks of sheep and goats during the spring and summer of 2019. Analysis and modelling of GPS data demonstrated no significant difference in individual cumulative exposure potential within each flock when animal behaviours with probability/uncertainties were considered. However, when daily cumulative exposure potential was calculated without consideration of animal behaviour or probability/uncertainties, significant differences among animals within a herd were observed, which does not match animal grazing behaviours reported by livestock owners. These results suggest that the proposed method including behaviour subgroups with probability/uncertainties more closely resembled the observed grazing behaviours. Results from the research may be used for future intervention and policy-making on remediation efforts in communities where grazing livestock may encounter environmental contaminants.

Hierarchical Cluster Analysis of Dense GPS Data and Examination of the Nature of the Clusters Associated With Regional Tectonics in Taiwan

AbstractCollision of the Luzon Volcanic Arc is the primary causative factor behind the creation of Taiwan Island. Additionally, the indention of the Peikang basement highs in the Taiwan Strait and the back arc spreading of the Okinawa Trough are responsible for the characteristic tectonics in Taiwan. Identification of active tectonic boundaries is important for understanding neotectonics in Taiwan. We analyzed Global Positioning System (GPS) horizontal velocity data in Taiwan with a hierarchical cluster analysis method. We also developed a statistical scheme introducing information entropy to quantitatively assess the fuzziness of the obtained cluster boundaries, which enables us to distinguish a trustworthy discontinuity. The hierarchical representation, which is expressed by a dendrogram, suggests the relative importance of tectonic sources in this region. The major clusters, which appear at higher hierarchy, are likely to represent major tectonic features such as the Longitudinal Valley fault and lateral extrusion in southwest Taiwan. Those at lower hierarchy suggest velocity discontinuities associated with local geological structures such as active faults. For example, boundaries in east offshore Taiwan and southern Taiwan are identified without using geological information by this analysis. In addition to the identification of these clear tectonic boundaries, our statistical cluster assessment shows the existence of fuzzy cluster boundaries along the Coastal Plain and the Western Foothills, reflecting continuum deformation in west Taiwan.

A pilot study using wearable global positioning system data loggers to compare water contact levels: Schistosoma haematobium infection in pre-school-age children (PSAC) and their mothers at Barombi Kotto, Cameroon.

Barombi Kotto, Cameroon serves as a reference location for assessing intervention strategies against Schistosoma haematobium. As part of a pilot study, the whole community was treated with praziquantel, inclusive of pre-school-age children (PSAC) and their mothers. One year later, egg-patent infections were reassessed and water contact patterns of 12 pairs of PSAC and their mothers were measured with global positioning system (GPS) data loggers. A substantial reduction in general infection prevalence, from 44.8% to 12.2%, was observed but certain PSAC and mothers continued to have egg-patent infections. Analysis of GPS data demonstrated similar water contact levels between the child and mother groups, although certain individuals were numerical outliers. This study shows the potential of GPS data loggers to clarify the at-risk status of PSAC and mothers.

Análise e visualização de dados de rastreamento para caracterização da logística urbana

Este estudo tem como objetivo aplicar técnicas de análise e visualização de dados GPS (Global Positioning System) para entender o comportamento do transporte urbano de carga em algumas capitais do país, através de indicadores logísticos como distribuição dos pontos de entrega, distribuição do volume de caminhões ao longo do tempo (dia da semana e hora do dia), etc. Para tanto, utilizaram-se duas bases de dados de rastre­amento de veículos, distintas, sendo a primeira fornecida por duas empresas varejistas que já possuíam tais dados por questões de segurança e monitoramento do compor­tamento dos motoristas, e a segunda disponibilizada por uma empresa que presta ser­viços de fornecimento de mapas e possui dados de diversas empresas, em sua maioria prestadores de serviço de monitoramento de veículos. Para o processamento dos da­dos foram usadas ferramentas de análise de grandes volumes de dados geoespaciais (geospatial big data). Para ambas as bases foi possível analisar, para o período de 06 a 10 de outubro de 2014 (segunda à sexta), o padrão de distribuição dos caminhões por dia da semana, cujas análises apontam para uma quantidade menor de veículos circu­lando na segunda-feira, em relação aos outros dias da semana (terça à sexta).

Plate Boundary Observatory and related networks: GPS data analysis methods and geodetic products

AbstractThe Geodesy Advancing Geosciences and EarthScope (GAGE) Facility Global Positioning System (GPS) Data Analysis Centers produce position time series, velocities, and other parameters for approximately 2000 continuously operating GPS receivers spanning a quadrant of Earth's surface encompassing the high Arctic, North America, and Caribbean. The purpose of this review is to document the methodology for generating station positions and their evolution over time and to describe the requisite trade‐offs involved with combination of results. GAGE GPS analysis involves formal merging within a Kalman filter of two independent, loosely constrained solutions: one is based on precise point positioning produced with the GIPSY/OASIS software at Central Washington University and the other is a network solution based on phase and range double‐differencing produced with the GAMIT software at New Mexico Institute of Mining and Technology. The primary products generated are the position time series that show motions relative to a North America reference frame and secular motions of the stations represented in the velocity field. The position time series themselves contain a multitude of signals in addition to the secular motions. Coseismic and postseismic signals, seasonal signals from hydrology, and transient events, some understood and others not yet fully explained, are all evident in the time series and ready for further analysis and interpretation. We explore the impact of analysis assumptions on the reference frame realization and on the final solutions, and we compare within the GAGE solutions and with others.

Comparison of the historic seismicity and strain-rate pattern from a dense GPS-GNSS network solution in the Italian Peninsula

We present a dense crustal velocity field and corresponding strain-rate pattern computed using Global Positioning System (GPS)- Global Navigation Satellite System (GNSS) data from several hundred permanent stations in the Italian Peninsula. GPS data analysis is based on the GAMIT/GLOBK 10.6 software, which was developed and maintained mainly by Massachusetts Institute of Technology (MIT), using tools based on the distributed-sessions approach implemented in this package. The GPS data span the period from January 2008 to December 2012 and come from several different permanent GPS networks in Italy. The GLOBK package implemented in the last version of the GAMIT package is used to compute the position time-series and velocities registered in the International Terrestrial Reference Frame (ITRF) 2008. The resulting high-density intra-plate velocity field provides indications of the tectonics of the Mediterranean region. A computation of the strain-rate pattern from GPS data is performed and compared with the map of the epicentral locations of historical earthquakes that occurred in the last 1000 years in the Italian territory, showing that, in general, higher crustal deformation rates are active in regions affected by seismicity of greater magnitude.

Seasonal Hydrological Loading in Southern Tibet Detected by Joint Analysis of GPS and GRACE.

In southern Tibet, ongoing vertical and horizontal motions due to the collision between India and Eurasia are monitored by large numbers of global positioning system (GPS) continuous and campaign sites installed in the past decade. Displacements measured by GPS usually include tectonic deformation as well as non-tectonic, time-dependent signals. To estimate the regional long-term tectonic deformation using GPS more precisely, seasonal elastic deformation signals associated with surface loading must be removed from the observations. In this study, we focus on seasonal variation in vertical and horizontal motions of southern Tibet by performing a joint analysis of GRACE (Gravity Recovery and Climate Experiment) and GPS data, not only using continuous sites but also GPS campaign-mode sites. We found that the GPS-observed and GRACE-modeled seasonal oscillations are in good agreements, and a seasonal displacement model demonstrates that the main reason for seasonal variations in southern Tibet is from the summer monsoon and its precipitation. The biggest loading appears from July to August in the summer season. Vertical deformations observed by GPS and modeled by GRACE are two to three times larger than horizontal oscillations, and the north components demonstrate larger amplitudes than the east components. We corrected the GPS position time series using the GRACE-modeled seasonal variations, which gives significant reductions in the misfit and weighted root-mean-squares (WRMS). Misfit ( divided by degree of freedom) reductions for campaign sites range between 20% and 56% for the vertical component, and are much smaller for the horizontal components. Moreover, time series of continuous GPS (cGPS) sites near the 2015 Nepal earthquakes must be corrected using appropriate models of seasonal loading for analyzing postseismic deformation to avoid biasing estimates of the postseismic relaxation.

14 years of GPS tropospheric delays in the French–Italian border region: comparisons and first application in a case study

Global Positioning System (GPS) data from 181 permanent stations extracted from different networks covering France and the Italian part of the Alps are used to estimate a homogeneous set of tropospheric parameters over 14 years (from January 1998 to May 2012). The tropospheric Zenith Total Delay (ZTD) quantified in the GPS data analysis is closely related to the value of integrated water vapor above each GPS station. GPS ZTD is already successfully used for operational weather prediction and meteorological analyses, providing valuable data to improve our comprehension of the tropospheric water cycle and in particular to improve the prediction of precipitations. Moreover, GPS tropospheric measurements are intrinsically stable, so that long-term observations represent a signi``ficant contribution to climatological studies. The results of a homogeneous reanalysis of up to 14 years of data with MIT’s GAMIT/GLOBK software are presented. The estimated tropospheric parameters are one ZTD every 2 h and one couple of horizontal tropospheric gradients, seven times a day for each station, simultaneously with a daily positioning solution. A quality check of the tropospheric parameter time series identifies offsets, for example, due to instrument changes at individual sites. Our analysis strategy using the empirical GMF is validated by a comparison with the new GPT2 model. Moreover, a comparison with the IGS analysis of 1 year is provided for common stations. The resulting verified time series can be used for meteorological and climatological studies. As first examples, we present a convergence test for the ZTD change in time and a regional climatological approach that could permit identifying specific patterns of ZTD variation that are related to severe weather events. The 181 ZTD and gradient time series are made available in the Reseau National GPS permanent (RENAG) database.

Combining GPS and VLBI for inter-continental frequency transfer

For decades the global positioning system (GPS) has been the only space geodetic technique routinely used for inter-continental frequency transfer applications. In the past very long baseline interferometry (VLBI) has also been considered for this purpose and the method’s capabilities were studied several times. However, compared to GPS current VLBI technology only provides few observations per hour, thus limiting its potential to improve frequency comparisons. We therefore investigate the effect of combining GPS and VLBI on the observation level in order to draw the maximum benefit from the strength of each individual technique. As a test-bed for our study we use the CONT11 campaign observed in 2011. First we review the frequency transfer performance that can be achieved with independent technique-specific analyses, both with individual software packages and with the multi-technique software c5++. With this analysis approach both techniques, GPS and VLBI, show similar frequency link instabilities at the level of 10−14 to 10−15 (MDEV) on inter-continental baselines for averaging times of one day. Then we use the c5++ software for a combined analysis of GPS and VLBI data on the observation level. We demonstrate that our combination approach leads to small but consistent improvements for frequency transfer of up to 10%, in particular for averaging periods longer than 3000 s.

Detecting complex eruption sequence and directionality from high-rate geodetic observations: The August 6, 2012 Te Maari eruption, Tongariro, New Zealand

The Tongariro Te Maari crater, New Zealand, erupted for the first time in over 80years on August 6, 2012. Because it occurred at night, the short-lived eruption prevented direct visual observations, hence presenting some challenges for understanding the complex eruptive sequence and reach of the various explosions. Using 1Hz Global Positioning System (GPS) data from the local volcano monitoring network, we computed the GPS LC phase residuals and SNR data at the time of the eruption and show that several processes successively affected the signal at the closest GPS station. Firstly, the signal from one of the satellites shows two successive drops of SNR caused by the presence of two distinct dense ash-laden plumes near the vent, produced successively by the second and last of the main eruption pulses. Secondly, we show that a gas-charged debris avalanche and a lateral blast successively entrained hot and/or humid air over 3km away from the vent, atop the VGKR GPS station. While the limited amount of data prevents fully quantitative analyses and estimates of temperature or humidity in the lateral air flow, our results document the first recorded detection of a small-scale lateral plume by GPS technology. They highlight the potential of GPS data analysis for improving our understanding of eruptive sequences when visual observations are limited.

Teaching High-Accuracy Global Positioning System to Undergraduates Using Online Processing Services

ABSTRACTHigh-accuracy Global Positioning System (GPS) has become an important geoscientific tool used to measure ground motions associated with plate movements, glacial movements, volcanoes, active faults, landslides, subsidence, slow earthquake events, as well as large earthquakes. Complex calculations are required in order to achieve high-precision positions and thereby high-accuracy displacement measurements. It is difficult to familiarize undergraduates with the complex data processing within a period of one semester. Several national organizations offer free online GPS processing services. Using these online services, a GPS beginner can bypass the complex aspect of data processing and focus on applications of the high-accuracy GPS technology. This paper introduces the author's experience using Online Positioning User Service, provided by the National Geodetic Survey (NGS) and Automatic Precise Positioning Service, provided by the Jet Propulsion Laboratory (JPL) in teaching two undergraduate courses, Applications of GPS in Geosciences and Geological Hazards, at the University of Puerto Rico at Mayaguez. Two class projects, “Where is My House?” and “GPS Landslide Monitoring,” were designed to practice GPS data collection, processing, and analysis. The enrollments of the two courses were about 10 senior undergraduate students. Online GPS data processing helped both the instructor and students in teaching and learning the intricacies of GPS data processing, understanding different reference frames and coordinate systems, and familiarizing local permanent reference stations. Students who had taken the GPS classes often help professors in the geology department and other departments to survey field sites with centimeter-level accuracy.

Comparative Analysis of GPS Data

Abstract. The goal of this project is to calculate the distance traveled during a bike ride around the University of South Florida using information gathered by a GPS (Global Positioning System) application on a smartphone. We calculate the route distance in two ways: from latitudes and longitudes using the haversine formula and 2) from velocities and times using the trapezoidal rule. These computed distances were compared to the distance given by the smartphone application.

Coastal sea level measurements using a single geodetic GPS receiver

This paper presents a method to derive local sea level variations using data from a single geodetic-quality Global Navigation Satellite System (GNSS) receiver using GPS (Global Positioning System) signals. This method is based on multipath theory for specular reflections and the use of Signal-to-Noise Ratio (SNR) data. The technique could be valuable for altimeter calibration and validation. Data from two test sites, a dedicated GPS tide gauge at the Onsala Space Observatory (OSO) in Sweden and the Friday Harbor GPS site of the EarthScope Plate Boundary Observatory (PBO) in USA, are analyzed. The sea level results are compared to independently observed sea level data from nearby and in situ tide gauges. For OSO, the Root-Mean-Square (RMS) agreement is better than 5cm, while it is in the order of 10cm for Friday Harbor. The correlation coefficients are better than 0.97 for both sites. For OSO, the SNR-based results are also compared with results from a geodetic analysis of GPS data of a two receivers/antennae tide gauge installation. The SNR-based analysis results in a slightly worse RMS agreement with respect to the independent tide gauge data than the geodetic analysis (4.8cm and 4.0cm, respectively). However, it provides results even for rough sea surface conditions when the two receivers/antennae installation no longer records the necessary data for a geodetic analysis.

Global Positioning System Data Analysis: Velocity Ranges and a New Definition of Sprinting for Field Sport Athletes

Global positioning system (GPS) technology has improved the speed, accuracy, and ease of time-motion analyses of field sport athletes. The large volume of numerical data generated by GPS technology is usually summarized by reporting the distance traveled and time spent in various locomotor categories (e.g., walking, jogging, and running). There are a variety of definitions used in the literature to represent these categories, which makes it nearly impossible to compare findings among studies. The purpose of this work was to propose standard definitions (velocity ranges) that were determined by an objective analysis of time-motion data. In addition, we discuss the limitations of the existing definition of a sprint and present a new definition of sprinting for field sport athletes. Twenty-five GPS data files collected from 5 different sports (men's and women's field hockey, men's and women's soccer, and Australian Rules Football) were analyzed to identify the average velocity distribution. A curve fitting process was then used to determine the optimal placement of 4 Gaussian curves representing the typical locomotor categories. Based on the findings of these analyses, we make recommendations about sport-specific velocity ranges to be used in future time-motion studies of field sport athletes. We also suggest that a sprint be defined as any movement that reaches or exceeds the sprint threshold velocity for at least 1 second and any movement with an acceleration that occurs within the highest 5% of accelerations found in the corresponding velocity range. From a practical perspective, these analyses provide conditioning coaches with information on the high-intensity sprinting demands of field sport athletes, while also providing a novel method of capturing maximal effort, short-duration sprints.

Variability of GPS derived water vapor and comparison with MODIS data over the Indo-Gangetic plains

The water vapor is one of the important constituents of the atmosphere that affects the thermodynamics of the atmosphere and has direct impact on the weather conditions. The total column atmospheric water vapor, obtained from Global Positioning System (GPS) and Moderate Resolution Imaging Spectroradiometer (MODIS), is found to be very dynamic over the Indo-Gangetic (IG) plains. In this paper, we present an analysis of GPS data recently deployed (as of May 2007) on the campus of Banaras Hindu University, Varanasi (latitude 25°15′N, longitude 82°59′E). Further, we have compared the variability of water vapor from Kanpur GPS, AERONET and MODIS water vapor data for the year 2007. The monthly variability of water vapor shows characteristic features and dynamics of water vapor between two closely spaced GPS stations, found to be controlled by monsoon dynamics and wind pattern.

Towards accurate determination of surface height using modern geoinformatic methods: possibilities and limitations

Over recent decades several modern geoinformatic height-finding methods have emerged, including global positioning system (GPS), interferometric radar, and airborne laser scanner (ALS) or lidar. In conjunction with the conventional survey and photogrammetric method, they have found wide applications that demand varying levels of accuracy. In this paper, the principles of each method are briefly summarized. The discussion then concentrates on the accuracy level achievable with each method. The factors that affect the accuracy, wherever possible, are comprehensively evaluated. This review has revealed that the highest accuracy achievable is still with the levelling method, followed by the photogrammetric method. This situation is likely to change in light of real-time kinematic GPS coupled with ALS. In contrast to the imaging methods that are suited to obtain highly accurate, fine-resolution digital elevation models (DEMs) at a local scale, GPS is the most efficient at obtaining heights at spots or along lines accurately. ALS is the only method applicable to acquisition of subsurface heights in vegetated areas. These airborne methods are complementary to their space-borne counterparts, such as Shuttle Radar Topographic Mapping and Shuttle Laser Altimeter, both being ideal in obtaining DEMs at the regional and global scales. The synergistic use of GPS with lidar offers the best hope in obtaining cm-level accuracies essential for monitoring ground subsidence and tectonic uplift. Height measurements accurate to subcentimetres needed for national levelling surveys are possible only after the tropospheric path delay is externally calibrated using Raman lidar data during GPS data analysis.

Assessment of GPS data for meteorological applications over Africa: Study of error sources and analysis of positioning accuracy

The aim of this study is to assess the availability and quality of data from the International GNSS Service (IGS) Global Positioning System (GPS) network in Africa, especially for retrieving zenith tropospheric delay (ZTD), from which precipitable water vapour (PWV) can be derived, in view of application to the African Monsoon Multidisciplinary Analysis (AMMA) project. Three major error sources for the GPS data analysis evaluating PWV in Africa are the accuracy of the satellite orbits, the correction for the radio delay induced by the ionosphere and the vertical site displacements due to ocean loading. The first part of this study examines these error sources and the validity of GPS data for meteorological applications in Africa in dedicated analyses spanning the year 2001. These analyses were performed using the IGS precise orbits. Weak degradation of baseline precision with increasing baseline lengths suggests that the average orbital error is not limiting the GPS analysis in Africa. The impact of the ionosphere has been evaluated during a maximum of solar activity in 2001. The loss of L 2 data has actually been observed. It amounts to 2% on average for 2001, with maxima of 8% during magnetic storm events. A slight decrease in formal accuracy of ZTD seems to be related to the loss of L 2 data at the end of the day. This indicates that scintillation effects are present in the GPS observations but however are not a major limitation. The impact of ocean loading is found to be significant on ZTD estimates (up to ±2 mm in equivalent PWV). The use of a proper ocean loading model eliminates this effect. The second aspect of this study concerns the IGS analysis quality for the African stations. The accuracy has been assessed through position dispersion between individual solutions and the most recent version of the IGS combined solution IGb00, and residuals from the transformation of the IGS combined solution into the International Terrestrial Reference Frame 2005. The positioning performance of the IGS analysis is consistent with an accuracy in ZTD of ±6 mm (±1 mm in PWV), as requested for meteorological applications such as planned in AMMA.

Geodetic constraints on kinematics of southwestern Bulgaria from GPS and levelling data

AbstractSouthwestern Bulgaria belongs to the southern marginal parts of the central Balkan neotectonic region and borders the northern side of the highly seismic north Aegean region. The recent horizontal and vertical motion of the tectonic structures is controlled primarily by the collision stage, caused by continuing ENE palaeosubduction in the Ionian and Adriatic seas and extensional processes northwards of the North Aegean Trough. The present-day generation of small to moderate seismicity and crustal faulting suggests that the complex tectonic processes in the SW Bulgaria region are active. To monitor and study the tectonic deformation in SW Bulgaria, a global positioning system (GPS) network was established in early 2001. Analysis of GPS data from 1996 to 2004 resulted in a horizontal velocity field representing active surface deformations. Horizontal velocities at 38 GPS sites with respect to stable Eurasia are obtained. A new map of the recent vertical velocities is compiled, based on recomputed data from the repeated precise levelling for the period 1929–1991. We obtained evidence of recent active faulting. Based on the geological and geodetic data the SW Bulgaria is separated into five blocks with homogeneous kinematic behaviour. The average motion of each block varies from 1.3 to 3.4 mm a−1, and the whole region velocity is c. 1.8±0.7 mm a−1 in a direction N154° with respect to stable Eurasia. Geodetic data correlate well with the geological data on neotectonic motions in SW Bulgaria.