Global Positioning System Techniques Research Articles

A GPS multipath mitigation method in coordinate-domain considering the effects of gross errors and missing data

Multipath is a significant obstacle to achieving high-precision deformation monitoring using the Global Positioning System (GPS) technique. Sidereal filtering (SF) can mitigate GPS multipath effects based on the multipath models derived from historical measurements, but its practical application in complex scenarios is still challenging due to unavoidable gross errors and missing data problems. In this paper, an improved SF algorithm is proposed that accurately extracts multipath immune to the effects of gross errors and missing values in historical measurements, aiming to obtain accurate displacements in a harsh environment. Specifically, a gross error detection method is first developed based on the dynamic time warping (DTW) algorithm to filter gross errors. Then, we adopt the multichannel singular spectrum analysis (MSSA) algorithm to extract initial multipath errors. Finally, we propose a weighted fusion (WF) algorithm to eliminate the impact of missing values and obtain the final multipath sequences. Extensive experiments with datasets collected from a real-world landslide, including both stable and sliding stations, demonstrate the effectiveness of our proposed method. Results show that compared with the traditional SF method, our proposed method can effectively mitigate the effects of gross errors and missing values on multipath modeling, with the multipath filtering accuracy improving by approximately 12% and 21% for stable and sliding scenarios, respectively.

Improved RSSI Indoor Localization in IoT Systems with Machine Learning Algorithms

Recent developments in machine learning algorithms are playing a significant role in wireless communication and Internet of Things (IoT) systems. Location-based Internet of Things services (LBIoTS) are considered one of the primary applications among those IoT applications. The key information involved in LBIoTS is finding an object’s geographical location. The Global Positioning System (GPS) technique does not perform better in indoor environments due to multipath. Numerous methods have been investigated for indoor localization scenarios. However, the precise location estimation of a moving object in such an application is challenging due to the high signal fluctuations. Therefore, this paper presents machine learning algorithms to estimate the object’s location based on the Received Signal Strength Indicator (RSSI) values collected through Bluetooth low-energy (BLE)-based nodes. In this experiment, we utilize a publicly available RSSI dataset. The RSSI data are collected from different BLE ibeacon nodes installed in a complex indoor environment with labels. Then, the RSSI data are linearized using the weighted least-squares method and filtered using moving average filters. Moreover, machine learning algorithms are used for training and testing the dataset to estimate the precise location of the objects. All the proposed algorithms were tested and evaluated under their different hyperparameters. The tested models provided approximately 85% accuracy for KNN, 84% for SVM and 76% accuracy in FFNN.

Studying spatio-temporal patterns of vertical displacements caused by groundwater mass changes observed with GPS

The sensitivity of Global Positioning System (GPS) technique to detect displacements caused by Total Water Storage (TWS) changes has already been analyzed, while its sensitivity to individual TWS components, such as groundwater, is still in question. We use the probabilistic Principal Component Analysis (pPCA) to examine the spatio-temporal variations of vertical displacements from 98 GPS stations located in 9 regions of the world recognized as those where changes in groundwater masses are the most significant. To study the Earth's crust displacements induced by changes in groundwater masses, we remove from GPS displacements those induced by changes in masses of other water storage components using the WaterGAP Global Hydrology Model (WGHM). For validation purposes, displacements predicted by the Gravity Recovery and Climate Experiment (GRACE) missions from which the WGHM compartments other than groundwater are subtracted are also used. We estimate an average global trend of vertical displacements induced by groundwater mass changes equal to 0.4 ± 0.17 mm/yr for GRACE-WGHM differences. We observe that this trend is overestimated by groundwater-induced displacements estimated for GPS-WGHM differences for several regions around the world and mostly underestimated by WGHM. Spatio-temporal patterns are very coherent between GPS-WGHM differences and GRACE-WGHM differences with significant signatures observed for periods of intense natural and/or human-induced groundwater mass changes. We show that the determined GRACE-WGHM differences and GPS-WGHM differences capture most of the wet and dry periods reflected by the Standardized Precipitation Evapotranspiration Index (SPEI). We also find that groundwater-induced displacements estimated from the three datasets we use, show a prominent 6-year cycle. Finally, we demonstrate that GPS displacements can add very essential information to study and monitor local displacements due to groundwater mass changes and may successfully contribute to the climate-related research.

A traffic big data analysis on relationships between urban planning and traffic noise level--taking Dongguan Demonstration Area, China as an example

With the promotion of smart city research, traffic big data has become a new way to study urban traffic noise. Taking Dongguan Demonstration Area, China as an example, this research discussed the relationships between traffic noise levels and urban plannings using geographic information scienceGIS, global positioning system (GPS) techniques and OpenITS Organization OpenData. The results showed that, for the whole area, some planning factors, say global integration, local integration (R=500m), global betweenness, local betweenness (R=500m) and number of points of interest (POIs) had significant positive correlations with the daytime traffic noise levels. Among them, the number of POIs had the strongest correlation with the traffic noise levels (r=0.560 p<0.01). However, the degree of influence of each variable on traffic noise levels can be changed with geographical locations. This research also identified specific areas where traffic noise levels were negatively correlated with local integration and local betweenness, which had great potential to provide a recreational and peaceful place for people to walk. Therefore, the urban areas' centers and fringes can be studied separately to effectively control traffic noise by changing the urban plannings.

On the Establishment of a Precise GPS Network in Khartoum State

The use of the Global Positioning System (GPS) as a fast and efficient alternative in the geodetic network measurements has become a common practice worldwide. The advantages of using the GPS technique compared to the traditional surveying methods are based on accuracy, time and cost. In this study, the static-mode of GPS measurement technique has been utilized to establish a precise geodetic network in Khartoum State. The network was referenced to a single control station that is related to the International Terrestrial Reference Frame (ITRF 2005). A number of six points have been constructed and observed around Khartoum State. In particular, seven observation sessions were conducted that gave an over determined system. The least-squares method was used in the adjustment of the GPS network. Two methods were utilized for the adjustment, namely, the parametric and the condition equation methods. The most probable values of the coordinates of the newly-established points were computed from both methods and they were found to be identical. The average standard deviation of the X, Y, and Z coordinates are ±1.36 cm, ±1.12 cm, & ±0.69 cm respectively.

Testing Patch, Helix and Vertical Dipole GPS Antennas with without Choke Ring Frame

Abstract: The antenna is the connecting part between Global Positioning System (GPS) satellite and receiver, and it works on transferring the satellite signal propagation to the receiver with minimum interruption. This is beside the main role that GPS antenna can play for accurate and precise positioning. High quality GPS antennas have high gain, systematic radiation pattern, Right Hand Circular Polarization (RHCP), and low directivity. Multipath error is a principal error source connected with GPS positioning and it can be mitigated using better antenna design. GPS antennas tend to be provided with choke ring frame for protection from the reflected RHCP electromagnetic waves. In this paper, the performance of three different types of GPS antenna, namely: Microstrip Patch Antenna (MPA), Helix antenna (HA), and Vertical Dipole antenna (VDA), with and without choke ring frame, has been investigated using single frequency GPS receiver. The antennas have been examined under the same GPS environment, including satellites constellation, geometry, and surroundings, with different heights from the ground reflector surface for multipath evaluation. Short base-line kinematic differential code GPS (DGPS) technique has been used for removing and mitigating the main GPS error sources and focusing on multipath effect. Satellite residuals and the quality of the obtained positioning have been considered for evaluating the performance of each antenna. The results have reflected the ability of choke ring frames to improve the performance of the three GPS antennas with different rates in multipath areas, and illustrate the advantages and limitations of each antenna. Keywords: Micro-strip, Patch, Helix, Vertical Dipole, GPS, Choke Ring Antenna, Multipath.

Landslide Assessment and Monitoring along the Jinsha River, Southwest China, by Combining InSAR and GPS Techniques

This paper focuses on ancient landslides located along the Jinsha River between the Ahai hydropower station (AHHs) and Liyuan hydropower station (LYHs). High-precision landslide monitoring and accurate understanding of inducing factors are important for landslide stability analysis. However, it is often difficult to monitor and analyze landslide movement due to rough terrain and the complex inducing factors in the mountain area. In this paper, the ancient landslides can be monitored by distributed scatterers-based interferometric synthetic aperture radar (DS-InSAR) technology and global positioning systems (GPS). DS-InSAR can obtain enough measurement points based on the persistent scatterers and distributed scatterers. Besides, we present the results of GPS measurement as a comparison and supplement to DS-InSAR. Our results illustrate that DS-InSAR measurement and GPS measurement show high-level consistency. To comprehensively analyze the triggering factors of landslide deformation, we derive the spatiotemporal movement characteristics of the XinJian (XJ) landslide and find that the XJ landslide movement is very nonuniform, which is closely related to soil weathering. The XJ landslide movement undergoes periodic acceleration. We deduce that the motion of the landslide may be affected by precipitation and water level fluctuation and indicate that the combination of precipitation and water level fluctuation is the most serious triggering factor. During the period from August to September, the rate of landslide movement reached a peak value, which was highly consistent with the precipitation and water level records. Additionally, the rescaled range method (R/S) is used to analyze the stability of the XJ landslide. The results show that hydrological conditions are an essential factor in the stability of the landslide. In other words, the more precipitation there is, the larger the water level changes and the more unstable the landslide.

PERFORMANCE OF SITE VELOCITY PREDICTION IN SUNDALAND

Abstract. Global Positioning System (GPS) technique has been extensively implemented in determination of crustal deformation globally. With the ability of providing solution up to milimeter (mm) level, this technique has proven to provide a precise estimate of site velocity that represents the actual motion of tectonic plate over a period. Therefore, this study aims to evaluate the site velocity estimation from GPS-derived daily position of station, respective to the global plate motion model and predicted site velocity via Least-Squares Collocation (LSC) method within the tectonically active region of Sundaland. The findings have indicated that stations with precise velocity estimates were consistent with global plate model and predicted velocity, with velocity residuals of 5 mm – 10 mm. However, stations that were severely impacted by continuous earthquake events such as in Sumatra were believed to be induced by the impact with consistently large velocity residuals up to 37 mm. Following the outcomes, this study has provided an insight on the post-seismic decay period plate motion which are induced by continuous tectonic activities respective to modelled plate motion.

High-Precision UWB-Based Localisation for UAV in Extremely Confined Environments

In this paper, a high-precision ultra-wideband (UWB) based unmanned aerial vehicle (UAV) localisation approach is proposed for applications in extremely confined environments. It is motivated by the emerging demand on autonomous inspection in such environments that are hard or impossible for humans to access. Instead of the traditional localisation techniques such as global positioning system (GPS), vision based or other localisation techniques, the UWB based localisation technique is adopted for precise UAV positioning due to its high accuracy, implementation simplicity and suitability in such environments. To avoid the requirement on strict synchronisation between sensor nodes and provide decimetre-level accuracy, the proposed algorithm combined the two-way time-of-flight (TW-TOF) localisation scheme with the maximum likelihood estimation (MLE) method. This differs from applications in other environments, the number and deployment area of anchor nodes are highly restricted in such environments. Therefore, an in-depth investigation for the anchor deployment strategies is presented to find the most suitable geometry configurations with accurate and robust performance. Finally, extensive simulations, static experiments and flight tests have been conducted to validate the localisation performance under different deployment strategies. The experiments show that average localisation error and standard deviation (STD) under 0.2 m and 0.07 m are obtainable by using our proposed approach under three different geometry configurations of anchor nodes. This is suitable for different applications in extremely confined environments.

Geocenter Variations Assessment using Frequency Analysis and Allan Variance Method

The objective of this work is to characterize the signals and noises of Geocenter variations time series obtained from different space geodesy techniques as Global Positioning System (GPS), Doppler Orbitography and Radiopositioning Integrated on Satellite (DORIS), and Satellite Laser Ranging (SLR). The proposed methodology is based on the estimation of periodic signals by performing frequency analysis using FAMOUS software (Frequency Analysis Mapping On Unusual Sampling) and evaluation of level and type of noises by Allan variance technique and Three Corned Hat (TCH) method. The available data concern 13 years (from 1993 to 2006) of weekly series of Geocenter residuals components and scale factor variations, according to ITRF2000. The results estimated are more accurate according to GPS and SLR of about 2-8 mm than DORIS of about 8-42 mm, for Geocenter. Better RMS of scale factor was obtained of about 0.1ppb (0.6mm) for GPS technique than SLR and DORIS with 0.6 and 0.9 ppb (3.6 and 5.4mm), respectively. The estimated seasonal signals amplitudes are in the range of few milimeters per technique with centimetre level for Z Geocenter component of DORIS. The Geocenter motion derived from SLR technique is more accurate and close to the geodynamic models. The noise analysis shows a dominant white noise in the SLR and DORIS Geocenter solutions at a level of 0.6-1 mm and 10-40 mm, respectively. However, the GPS solution is characterized by a flicker noise at millimetre level, relating to mismodeling systematic errors.

Quick and cost-effective mapping of subsistence and artisanal fishing areas within and adjacent to a marine protected area

Spatial information on artisanal fisheries is largely lacking, making subsequent management and threat or impact assessments difficult. Local knowledge, current and readily available mapping software and Global Positioning System (GPS) techniques were used to map small-scale (subsistence and artisanal) fishing areas within and adjacent to the western boundary of the Ponta do Ouro Partial Marine Reserve in southern Mozambique. Data on habitat types were collected in the field and combined with available literature. Thirty-one fishing areas were identified and mapped resulting in a total area of 293.1 km2 with a perimeter of 396.7 km, from the Inhaca Island lighthouse in the north to the Maputo River mouth in the south. Habitats within the fishing areas included isolated intertidal sand banks, seagrass beds, estuarine channels, as well as intertidal muddy areas adjacent to the coast. The fishing areas covered on average 9.5 km2 (SD=12.0) and varied immensely in size (0.3–50.1 km2). Overall, 58.4 % (171.2 km2) of the total fishing area mapped was located inside the reserve. Costs associated with data collection equated to an average of U$D 3.61 per mapped km2 or U$D 2.63 per km tracked. The method was found to be quick, cost-effective and easily replicable elsewhere.

Pipe Break Rate Assessment While Considering Physical and Operational Factors: A Methodology based on Global Positioning System and Data-Driven Techniques

An accurate prediction of pipes failure rate plays a substantial role in the management of Water Distribution Networks (WDNs). In this study, a field study was conducted to register pipes break and relevant causes in the WDN of Yazd City, Iran. In this way, 851 water pipes were incepted and localized by the Global Positioning System (GPS) apparatus. Then, 1033 failure cases were reported in the eight zones of understudy WDN during March-December 2014. Pipes break rate (BRP) was calculated using the depth of pipe installation (hP), number of failures (NP), the pressure of water pipes in operation (P), and age of pipe (AP). After completing a pipe break database, robust Artificial Intelligence models, namely Multivariate Adaptive Regression Spline (MARS), Gene-Expression Programming (GEP), and M5 Model Tree were employed to extract precise formulation for the pipes break rate estimation. Results of the proposed relationships demonstrated that the MARS model with Coefficient of Correlation (R) of 0.981 and Root Mean Square Error (RMSE) of 0.544 provided more satisfying efficiency than the M5 model (R = 0.888 and RMSE = 1.096). Furthermore, statistical results indicated that MARS and GEP models had comparatively at the same accuracy level. Explicit equations by Artificial Intelligence (AI) models were satisfactorily comparable with those obtained by literature review in terms of various conditions: physical, operational, and environmental factors and complexity of AI models. Through a probabilistic framework for the pipes break rate, the results of first-order reliability analysis indicated that the MARS technique had a highly satisfying performance when MARS-extracted-equation was assigned as a limit state function.

A novel moving-base RTK-GPS-Based wearable apparatus for precise localization of humans in peril

The paper in hand addresses the issue of precise positioning of a human in peril, who is supervised by means of carrying a novel wearable apparatus in the context of a crisis event. A completely Autonomous Unmanned Aerial Vehicle (AUAV) comprises the main component of an Autonomous Aerial Rescue System (AARS), namely the ROLFER (Robotic Lifeguard For Emergency Rescue), which has been specifically designed for instantaneous response and provision of assistance in Search and Rescue (SAR) scenarios. As short response times constitute a sine qua non criterion in SAR operations, all the accuracy issues of such systems have to be seriously accounted so as for a rescue mission or activity to be considered successful. After examining and evaluating the performance of several Global Positioning System (GPS) methods and techniques, the moving-base Real-Time Kinematics (RTK)-GPS technology was chosen due to its superior accuracy. Hardware and software configuration of the novel wearable apparatus prototype, as well as the architecture of the overall rescue system are described in detail in this paper. Experimental results from real flight tests of the proposed AARS and the effectiveness of the implemented moving-base RTK-GPS-based wearable apparatus are also presented here.

A Drought Monitoring Method Based on Precipitable Water Vapor and Precipitation

AbstractPrecipitable water vapor (PWV) with high precision and high temporal resolution can be obtained based on the global navigation and satellite positioning system (GNSS) technique, which is important for GNSS in disaster prevention and mitigation. However, related studies on drought monitoring using PWV have rarely been performed before, which becomes the focus of this paper. This paper proposes a novel drought monitoring method using GNSS-derived PWV and precipitation, and a multi-time-scale standardized precipitation conversion index (SPCI) is established. This index is different from the traditional index in terms of expression, standardization, and time scale. The proposed SPCI is then compared with the standardized precipitation index/standardized precipitation evapotranspiration index/self-calibrating Palmer drought severity index (SPI/SPEI/scPDSI) and applied to local and global drought monitoring. Validated results show that multi-time-scale SPCI has good consistency with the corresponding SPI/SPEI/scPDSI. The correlation between SPCI and SPEI is the strongest (more than 0.96) on a 12-month scale, which indicates the application potential of SPCI in drought monitoring. In addition, applications for regional (Queensland, Australia) and global drought/wet monitoring further verify the capability of the proposed SPCI. The average percentage deviations of drought/wet monitoring between SPCI and SPEI are 2.77% and 3.75%, respectively on a global scale. The above results show that the SPCI developed in this study is efficiently applied to global flood/wet studies.

Potential of airborne LiDAR data for terrain parameters extraction

LiDAR (Light Detection and Ranging) remote sensing is the most popular technology delivering higher detailed information and accuracy. LiDAR data is majorly used for generating a high-resolution digital elevation model (DEM), which is one of the primary data for most of the remote sensing applications. DEM forms the basis to derive other terrain parameters that are important to understand the topographic variations for the majority of applications. This research work highlights the potential of airborne LiDAR data for the extraction of terrain parameters. The airborne LiDAR dataset used in this study is of the St. Petersburg region of Russia. Terrain parameters like digital surface model (DSM), bare earth model (BEM), slope, aspect, curvature and terrain ruggedness index (TRI) are estimated from the airborne LiDAR data. Ground control points surveyed using Differential Global Positioning System (DGPS) technique are used to assess the accuracy of the generated digital elevation model. An RMSE of 1.30 cm is obtained for the generated DSM with a maximum error of 3.5 cm magnitude. A complete analysis of derived parameters is done to observe the accuracy achieved.

Extracting of Shoreline in Baltim Beach Using Remote Sensing and Global Positioning System (Gps) Techniques . (Dept. C ( Irrigation And Hydraulics ) )

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Determining the set of representative variables of real-world driving cycle of bus: a case study of Hanoi

This paper analysed the real-world driving data to determine the representative parameters of driving cycle for the purpose of the typical driving cycle development of bus in Hanoi. The real-world driving data of bus in Hanoi were collected by using the Global positioning system technique with 1Hz data update rate. The real-world driving data of fifteen bus routes in the inner city were collected continuously, on weekdays as well as at weekends. The data, then, were used to calculate 33 kinematics parameters reflecting the realistic driving characteristics, including vehicle-specific power. The hierarchical agglomerative clustering method was used to determine a minimal set of representative variables from the 33 kinematics parameters. The 14 representative parameters of the real-world driving cycle of bus in Hanoi were determined.

GIS-based assessment of morphological and hydrological parameters of Wainganga River Basin, Central India

River basin planning is a systematic approach to the specific problems related to availability and access to water for various purposes, and to simultaneously ensure the ecological integrity of a river system. GIS-based assessment of morphological and hydrological process inflows, rainfall–runoff modeling and regression equations was discussed using geographical information systems and remote sensing techniques. The Wainganga River emerges from a spring in the plains of Madhya Pradesh and has a meandering flow. The river is mostly shallow and wide in this region. The depth of the river increases in the backwaters of the Sanjay Sarovar Dam. In observation, the total number of streams of 27 sub-basins is 9472; the diverse geology implies geohydrological heterogeneity at the river basin scale. This heterogeneity could be amenable to comprehensive river-basin planning of recharge, discharge and conservation. The monthly rainfall–runoff models (R–R models) so developed are R = 1.019 * P − 418.20 height in the Bhimkund catchment area, and the lowest is R = 0.532 * P + 194.60 in Bamni catchment. The present study depicts the process of evaluating various morphological and hydrological parameters of the Wainganga River by applying remote sensing, geographical information system and global positioning system techniques. The data can be used for basin management, hydrological, and utilized in restoration and conservation of natural resource studies in the future.

Traffic Management System in Abuja City Center, using Geographic Information Systems (GIS) and Global Positioning System (GPS). A case study of FCT, Nigeria

In any city in the world, moving from one point to another is an endurance task. Regardless of the social status of the traveller, the situations under which persons travel are becoming challenging gradually. The condition of Abuja traffic is no diverse. Efforts were made in this study, to map traffic conditions along selected corridors of Federal Capital Territory (FCT) Abuja using Geographical Information System (GIS) and Global Positioning System (GPS) Techniques. The primary data used includes the geographical coordinates of the chosen traffic corridors using GPS, the extent of vehicle traffic congestion and traffic counts along the corridors. Whereas the secondary data used are Abuja FCT’s topographical and road map from the Abuja Geographical Information System (AGIS). The data obtained were entered and used to develop an information system for traffic conditions (TCIS). Data recovered and attribute spatial analysis were displayed using ArcGIS 10. The results were presented in a map format, making it easy to interpret and quick to make decisions. The results display different levels of congestion and vehicular volume along digital traffic corridors. The results will be beneficial for agencies in charge of traffic conditions planning and management in Abuja FCT. GIS-GPS are powerful tools for both spatial and non-spatial data analyses. From the analysis, it can provide traffic data (Speed, Level of Service, Traffic and Delay Time) to transport planners in road controlling authorities in order to understand congestion better, determine its causes and prioritise investment where it is most needed.

Accuracy Analysis of Aircraft Position at Departure Phase Using DGPS Method

Abstract The aim of this paper is to present the problem of implementation of the Differential Global Positioning System (DGPS) technique in positioning of the aircraft in air navigation. The aircraft coordinates were obtained based on Global Positioning System (GPS) code observations for DGPS method. The DGPS differential corrections were transmitted from reference station REF1 to airborne receiver using Ultra High Frequency (UHF) radio modem. The airborne Thales Mobile Mapper receiver was mounted in the cabin in Cessna 172 aircraft. The research test was conducted around the military aerodrome EPDE in Dęblin in Poland. In paper, the accuracy of aircraft positioning using DGPS technique is better than 1.5 m in geocentric XYZ frame and ellipsoidal BLh frame, respectively. In addition, the obtained accuracy of aircraft positioning is in agreement with International Civil Aviation Organization (ICAO) Required Navigation Performance (RNP) technical standards for departure phase of aircraft. The presented research method can be utilised in Ground-Based Augmentation System (GBAS) in air transport. In paper, also the accuracy results of DGPS method from flight test in Chełm are presented. The mean values of accuracy amount to ±1÷2 m for horizontal plane and ±4÷5 m for vertical plane.