Differential Global Positioning System Receiver Research Articles

Geospatial Approach to Route Optimisation for Security Architecture Improvement

Understanding the complexity of road networks is tiring, especially in finding the optimum routes for emergency response. Dynamic route optimisation is a decision-making process powered by mathematical models to formulate a strong basis for predicting the best path between any two points in a road network. Exploring the numerous interconnected routes in and out of a road network provides a strong foothold for securing lives and properties. This study presents the findings of route optimisation at the Federal University of Technology Minna, Gidan Kwano Campus. High Target Differential Global Positioning System receiver (DGPS), Handheld GPS (Garmin GPSmap 60Cx), Quick Bird Satellite Imagery, and Google Earth Images were used for data acquisition purposes. An ArcGIS network analyst for optimum route identification based on Dijktra’s algorithm was utilised for analysis. Five different optimisation tests were done and the optimised routes were compared with alternative routes from the network. The total travel distances for alternative and optimum routes are 11852.414 m and 16614.156 m respectively while the total travel times for alternative and optimum routes are 2135.35 s and 2993.25 s respectively. The study revealed all optimum routes are faster cumulatively by (11.7%) and are best for security and emergency responses. Ten unauthorised access roads to the campus were identified. The number of routes paving access to the campus shows that efforts towards ensuring security must be increased.

Evolution of Maritime GNSS and RNSS Performance Standards

The primary means for electronic position fixing in use in contemporary maritime transport are shipborne GPS (Global Positioning System) receivers or DGPS (Differential GPS) receivers. More advanced GNSS (Global Navigation Satellite System) or RNSS (Regional Navigation Satellite Systems) receivers are able to process combined signals from American GPS, Russian GLONASS, Chinese Beidou (BDS), European Galileo, Indian IRNSS, and Japan QZSS. Satellite-based augmentation systems (SBAS) are still not commonly used in the maritime domain, especially onboard vessels certified under international SOLAS convention. The issues and weaknesses of existing International Maritime Organization recommendations, guidelines, requirements, performance standards, and policies on GNSS shipborne sensors are discussed and presented in the paper. Many problems that have already been dealt with in other means of transportation are still to be solved in the maritime domain. The integrity monitoring is addressed as the main issue, and recommendations based on solutions implemented in aviation and the latest research are proposed. Finally, the strengths, weaknesses, opportunities, and threats awaiting maritime GNSS standardization process are outlined.

Accuracy Assessment for points coordinates surveyed using low-cost Unmanned Aerial Vehicle and Global Positioning System with 3Dsurvey and 3DF Zephyr software

Ground Control Points GCPs are the only way to obtain accurate positions in aerial surveys. At least three points should be utilized, and the model will get increasingly accurate in X, Y, and Z coordinates as the number rises. The accuracy of the 3D model created from aerial photography is also affected by the arrangement of GCPs. The goal of this research is to determine the optimal number and arrangement of GCPs in order to obtain the lowest possible error in point positioning. A conventional UAV called DJI Mavic 2 pro was used to photograph one and a half square kilometer site at an elevation equal to hundred meters from earth’s surface with nadir camera configuration. GSD (ground sampling distance) of 2.3 centimeters was used to collect 1515 pictures. 62 GCPs were observed in PPK (Post Processing kinematic) method using a DGPS (differential global positioning system) receiver GS 15 from Leica. The study area was split into two areas, one with a straight arrangement of GCPs and the other with a diagonal arrangement of GCPs. The pictures were processed using 3Dsurvey and 3DF Zephyr software utilizing a full bundle adjustment procedure with increasing GCPs number beginning with three GCPs and ending with twenty-six GCPs for both arrangement layout, with the other points serving as check points for the model’s accuracy at each attempt. The check point coordinates obtained were compared to the DGPS coordinates. The result indicates the optimal GCP number needed for the most accurate position and spread layout. That the minimum gap between adjacent GCPs ought to be not over than 100 meters and spread homogenously.

Study on the Positioning Accuracy of GNSS/INS Systems Supported by DGPS and RTK Receivers for Hydrographic Surveys

Hydrographic surveys, in accordance with the International Hydrographic Organization (IHO) S-44 standard, can be carried out in the following five orders: Exclusive, Special, 1a, 1b and 2, for which minimum accuracy requirements for the applied positioning system have been set out. They are as follows, respectively: 1, 2, 5, 5 and 20 m, with a confidence level of 95% in two-dimensional space. The Global Navigation Satellite System (GNSS) network solutions (accuracy: 2–3 cm (p = 0.95)) and the Differential Global Positioning System (DGPS) (accuracy: 1–2 m (p = 0.95)) are now commonly used positioning methods in hydrography. Due to the fact that a new order of hydrographic surveys has appeared in the IHO S-44 standard from 2020—Exclusive, looking at the current positioning accuracy of the DGPS system, it is not known whether it can be used in it. The aim of this article is to determine the usefulness of GNSS/Inertial Navigation Systems (INS) for hydrographic surveys. During the research, the following two INSs were used: Ekinox2-U and Ellipse-D by the SBG Systems, which were supported by DGPS and Real Time Kinematic (RTK) receivers. GNSS/INS measurements were carried out during the manoeuvring of the Autonomous/Unmanned Surface Vehicle (ASV/USV) named “HydroDron” on Kłodno lake in Zawory. The acquired data were processed using the mathematical model that allows us to assess whether any positioning system at a given point in time meets (or not) the accuracy requirements for each IHO order. The model was verified taking into account the historical and current test results of the DGPS and RTK systems. Tests have confirmed that the RTK system meets the requirements of all the IHO orders, even in situations where it is not functioning 100% properly. Moreover, it was proven that the DGPS system does not only meet the requirements provided for the most stringent IHO order, i.e., the Exclusive Order (horizontal position error ≤ 1 m (p = 0.95)). Statistical analyses showed that it was only a few centimetres away from meeting this criterion. Therefore, it can be expected that soon it will be used in all the IHO orders.

Using single and multiple unmanned aerial vehicles for microscopic driver behaviour data collection at freeway interchange ramps

This paper presents a detailed methodological framework for collecting microscopic driver and vehicle behaviour data over a long road segment with an application to the entire stretch of a freeway ramp segment using single and multiple unmanned aerial vehicles (UAVs). The methodology allows users to collect reliable and complete trajectories of traffic movements in areas with challenging physical characteristics (long road segment, horizontal curvature, changing elevation, and presence of shadow), challenging traffic characteristics (high traffic volume, high speeds, and high-speed changes), and restrictive regulations (UAVs prohibited from hovering over the freeway or the right-of-way). Different UAV setups are recommended and can be used depending on the site conditions. Specific commercial software and procedures used to complete the data collection are explained. The methodology was applied at two ramps and verified with speed data acquired from differential GPS receivers using three different error metrics. The results showed good performance of the proposed methodology, including when aerial videos were taken from oblique angles.

Analysis of Error in Geodetic Networks using Different Observation Methods

Now a day, the Global Positioning System (GPS) is used in engineering surveying application, civil engineering construction and for correct object positioning, as in other fields (soil mapping characterization, military applications, and so on). As a result of the multipath error that increases when GPS signal is reflected by smooth surfaces around the antenna, the accuracy of positioning is reduced. For GPS signals this effect mainly appears in the neighbourhood of large buildings. In this research the faculty of engineering at University of Tikrit was chosen as a study area and the points were established at nearby building whose surface was able to reflect the incoming signals. The reflected signal takes more time to reach the receiver than the direct signal. The multipath effect is caused by reflection of satellite signals (radio waves) on objects. This paper shows the result of error obtained by (RTK and static observations) in different situations based on the GPS signals with different differential GPS receiver’s system that was caused by multipath error reflected.

Method of Evaluating the Positioning System Capability for Complying with the Minimum Accuracy Requirements for the International Hydrographic Organization Orders.

According to the IHO (International Hydrographic Organization) S-44 standard, hydrographic surveys can be carried out in four categories, the so-called orders—special, 1a, 1b, and 2—for which minimum accuracy requirements for the applied positioning system have been set out. These amount to, respectively: 2 m, 5 m, 5 m, and 20 m at a confidence level of 0.95. It is widely assumed that GNSS (Global Navigation Satellite System) network solutions with an accuracy of 2–5 cm (p = 0.95) and maritime DGPS (Differential Global Positioning System) systems with an error of 1–2 m (p = 0.95) are currently the two main positioning methods in hydrography. Other positioning systems whose positioning accuracy increases from year to year (and which may serve as alternative solutions) have been omitted. The article proposes a method that enables an assessment of any given navigation positioning system in terms of its compliance (or non-compliance) with the minimum accuracy requirements specified for hydrographic surveys. The method concerned clearly assesses whether a particular positioning system meets the accuracy requirements set out for a particular IHO order. The model was verified, taking into account both past and present research results (stationary and dynamic) derived from tests on the following systems: DGPS, EGNOS (European Geostationary Navigation Overlay Service), and multi-GNSS receivers (GPS/GLONASS/BDS/Galileo). The study confirmed that the DGPS system meets the requirements for all IHO orders and proved that the EGNOS system can currently be applied in measurements in the orders 1a, 1b, and 2. On the other hand, multi-GNSS receivers meet the requirements for order 2, while some of them meet the requirements for orders 1a and 1b as well.

Method of Anomaly Measurement of GPS Elevation in Sea Area

In view of the problem of dynamic GPS elevation anomaly control measurement, the fitting model is optimized. Under the dynamic condition of the sea, the differential GPS receiver is used to design the measurement network according to the certain route. At the same time, the high range fitting method is used to select the GPS elevation linear fitting model and the barometer level height measurement for normal high contrast compensation measurement. . The method is used to preprocess the collected data in real time, and the real time analysis and compensation of the barometer leveling data for the fitting output results can effectively realize the regional GPS elevation measurement under the sea dynamic condition.

Generation of accurate digital elevation models from UAV acquired low percentage overlapping images

ABSTRACTDigital elevation models (DEMs) are very useful in solving various environmental problems such as planning and construction, hydrological and meteorological services, mining and oil industry, risk assessment, and hazard predictions, which makes their accurate production very essential. Attempt has been made in this research to investigate the robustness of DEMs produced from unmanned aerial vehicle sourced images with approximately 15–20% overlap. At 50 m altitude (flying height), over 90 overlapping images were acquired using a DJI Phantom quadcopter, and they were processed using Agisoft PhotoScan Digital Photogrammetric Software. The products generated are the three-dimensional model, dense point cloud, mesh surface, wired frame, orthomosaic, and the DEM. In order to ascertain the accuracy of the produced DEM, coordinates of selected points across the imaging area were extracted from the generated DEM. These coordinates were compared with those obtained using Hi-target differential global positioning system receiver. Using the National Standard for Spatial Data Accuracy, the derived horizontal and vertical accuracies are 0.0467 and 0.1151 m, respectively.

Changes of Marukh Glacier from 1945 to 2011

Field studies have been carried out in summer 2011 at Marukh Glacier located in western part of the Northern Caucasus. The studies included ground-based radio-echo sounding measurements at a frequency of 20 MHz and glacier surface elevation survey using a dual frequency differential GPS receiver. Changes of volume and surface area of the glacier for the period 1945–2011 have been estimated using aerial photo, satellite images and topographic maps analysis. It is founded that Marukh Glacier is retreating and has reduced its surface area by 17% for the past 66 years. Glacier volume is 0,276 km³ in 2011 and has decreased by 0,06 km³ since 1967.

UAV photogrammetry for topographic monitoring of coastal areas

Coastal areas suffer degradation due to the action of the sea and other natural and human-induced causes. Topographical changes in beaches and sand dunes need to be assessed, both after severe events and on a regular basis, to build models that can predict the evolution of these natural environments. This is an important application for airborne LIDAR, and conventional photogrammetry is also being used for regular monitoring programs of sensitive coastal areas. This paper analyses the use of unmanned aerial vehicles (UAV) to map and monitor sand dunes and beaches. A very light plane (SwingletCam) equipped with a very cheap, non-metric camera was used to acquire images with ground resolutions better than 5cm. The Agisoft Photoscan software was used to orientate the images, extract point clouds, build a digital surface model and produce orthoimage mosaics. The processing, which includes automatic aerial triangulation with camera calibration and subsequent model generation, was mostly automated. To achieve the best positional accuracy for the whole process, signalised ground control points were surveyed with a differential GPS receiver. Two very sensitive test areas on the Portuguese northwest coast were analysed. Detailed DSMs were obtained with 10cm grid spacing and vertical accuracy (RMS) ranging from 3.5 to 5.0cm, which is very similar to the image ground resolution (3.2–4.5cm). Where possible to assess, the planimetric accuracy of the orthoimage mosaics was found to be subpixel. Within the regular coastal monitoring programme being carried out in the region, UAVs can replace many of the conventional flights, with considerable gains in the cost of the data acquisition and without any loss in the quality of topographic and aerial imagery data.

Floating Dropsondes With DGPS Receiver for Real-Time Typhoon Monitoring

Both a geometrical correction and a residual error correction schemes are proposed to improve the positioning accuracy of a three-frequency differential global positioning system (DGPS) on the order of centimeters, using 1 s of received data, and the baseline can be up to 120 km. An ad hoc network of floating dropsondes bearing DGPS receivers is proposed to monitor the progress of a typhoon in real time. An empirical typhoon model is adopted to simulate the deployment of such a network in typhoon Morakot and hurricane Katrina to verify its feasibility.

Assessing GNSS correction signals for assisted guidance systems in agricultural vehicles

Accuracy levels achieved with differential global positioning system (DGPS) receivers in agricultural operations depend upon the quality of the correction signal. This study has assessed differential signal error from a Dedicated Base Station, OmniSTAR VBS, European Geostationary Navigation Overlay System, European reference frame-IP for internet protocol (EUREF-IP) and radio navigation satellite aided technique (RASANT). These signals were utilized in guidance assisting systems for agricultural applications, such as tillage, harvesting, planting and spraying, in which GPS receivers were used under dynamic conditions. Simulations of agricultural operations on different days and at different time slots and simultaneously recording the tractor′s geo-position from a DGPS receiver and the tractor′s geo-position from a real-time kinematic (RTK) GPS allowed the comparison of the GPS correction signals. The hardware used for tractor guidance was a lightbar (Trimble model EZ-Guide Plus) system. ANOVA statistics showed a significant difference between the accuracy of the correction signals from different sources. GPS correction signal recommendations to farmers depend upon the accuracy required for the specific operation: (a) Yield monitoring and soil sampling (<1 m) are possible with all the GPS correction signals accessed in any time slot. (b) Broadcast seeding, fertilizer and herbicide application (<0.5 m) are possible for 80% of time with OmniSTAR VBS, 40% of time with RASANT and EUREF-IP and 100% of time with a dedicated base station. (c) Transplanting and drill seeding (<0.04 m) are not possible with the accuracy correction provided by any one of the systems used in this study.

부산 북항에서 VTS 시스템에 의한 출입항 선박의 접이안 작업과정의 실시간 모니터링

The process of berthing/deberthing operations for entering/leaving vessels in Busan northern harbor was analyzed and evaluated by using an integrated VTS(vessel traffic service) system installed in the ship training center of Pukyong National University, Busan, Korea. The integrated VTS system used in this study was consisted of ARPA radar, ECDIS(electronic chart display and information system), backup(recording) system, CCTV(closed-circuit television) camera system, gyro-compass, differential GPS receiver, anemometer, AIS(automatic identification system), VHF(very high frequency) communication system, etc. The network of these systems was designed to communicate with each other automatically and to exchange the critical information about the course, speed, position and intended routes of other traffic vessels in the navigational channel and Busan northern harbor. To evaluate quantitatively the overall dynamic situation such as maneuvering motions for target vessel and its tugboats while in transit to and from the berth structure inside a harbor, all traffic information in Busan northern harbor was automatically acquired, displayed, evaluated and recorded. The results obtained in this study suggest that the real-time tracking information of traffic vessels acquired by using an integrated VTS system can be used as a useful reference data in evaluating and analyzing exactly the dynamic situation such as the collision between ship and berth structure, in the process of berthing/deberthing operations for entering/leaving vessels in the confined waters and harbor.

Sensor Fusion Applied to Autonomous Aerial Refueling

DOI: 10.2514/1.34589 A methodology for performing sensor fusion using differential Global Positioning System receivers, inertial measurements, wireless communication, and electro-optical measurements is presented. An estimation structure basedonanextendedKalman filterisdevelopedtoestimate thepreciserelativeposition,velocity,andattitudeoftwo aircraft flying incloseproximity. Theprojectisfocusedonthedevelopmentofthismethodologyforautomaticaerial refueling in which a boom control system uses the output of the sensor fusion to guide the boom into the receiver receptacle. Results from a real-time, hardware-in-the-loop demonstration are presented which show estimator performance and feedback control capability on a scaled model.

A Road Matching Method for Precise Vehicle Localization Using Hybrid Bayesian Network

This article presents a multisensor fusion strategy for a novel road-matching method designed to support real-time navigational features within advanced driver assistance systems. In road navigation, context, integrity, reliability and accuracy are essential qualities for road-matching methods. Particularly, managing multihypotheses is a useful strategy to treat ambiguous situations in the road-matching task. In this study, multisensor fusion and multimodal estimation are realized using a hybrid Bayesian network. To manage multihypothesis, multimodal estimation is proposed. Experimental results, using data from antilock braking system sensors, a differential global positioning system receiver, and an accurate digital roadmap illustrate the performance of the proposed approach, especially in ambiguous situations.

Development of a target oriented weed control system

Conventionally, herbicides are applied uniformly in the fields, while there is strong evidence that weeds are not distributed uniformly within crop fields and they tend to occur in clumps or patches. This manuscript presents the development of a prototype patch sprayer for target oriented weed control system by integration of differential global positioning system (DGPS), Geographical Information System (GIS), and solenoid-activated spray nozzles in response to signals generated by a displacement sensor. A set of Ashteck Promark2 DGPS receivers (fixed and rover) was used to collect weed position data in the test plots. A micro-controller was designed, fabricated and used to retrieve weed patch locations on the electronic map and simultaneously receiving grid signals from an infra-red displacement sensor mounted on the sprayer front wheel to generate and send activating signals to the sprayer nozzle solenoids. A randomized complete block experiment was conducted with three herbicide spraying treatments consisting of targeted patch spraying, conventional (uniform) spraying, and no-spraying (control) in three replications to assess the field performance. In the patch spraying treatment, spray mixture (Gramoxin, 10%) was sprayed only over the target (weed-infested) grids as controlled by a displacement sensor, an electronic weed map, and a microprocessor, while the conventional treatment plots received uniform and continuous application of the spray mixture. Patch spraying application was as effective as the conventional (uniform) application method in controlling weed infestation. The two spraying methods were significantly different at 99% confidence level with mean values of herbicide consumption rates of 40 and 12.2 l/ha for the conventional and patch spraying methods, respectively. This indicates that targeted weed patch herbicide application resulted in 69.5% saving compared to the conventional application.

Next-Generation Automated Vehicle Location Systems: Positioning at the Lane Level

The majority of today's automated vehicle location (AVL) systems use Global Positioning System (GPS) technology, which can provide position information with an accuracy of approximately 15 m. Recently, low-cost Differential GPS (DGPS) receivers, which have a positioning accuracy of approximate 2-3 m, have become available. With this increased accuracy, it is now possible to perform AVL down to specific roadway lanes. In this paper, a vehicle-lane-determining system is described, consisting of an onboard DGPS receiver that is connected with a wireless communications channel, a unique lane-level digital roadway database, a developed lane-matching algorithm, and a real-time vehicle location display. Lane-level positioning opens up the door for a number of new intelligent transportation system applications such as better fleet management, lane-based traffic measurements from probe vehicles, and lane-level navigation. The developed low-cost system has been tested on a number of roadways and has performed very well when used with accurately surveyed map data. Based on more than 100 000 s, it has correctly determined the lane 97% of the time.

Road Selection Using Multicriteria Fusion for the Road-Matching Problem

This paper presents a road selection strategy for novel road-matching methods that are designed to support real-time navigational features within Advanced Driving-Assistance Systems (ADAS). Selecting the most likely segment(s) is a crucial issue for the road-matching problem. The selection strategy merges several criteria using Belief theory. Particular attention is given to the development of belief functions from measurements and estimations of relative distances, headings, and velocities. Experimental results using data from antilock brake system sensors, the differential Global Positioning System receiver, and the accurate digital roadmap illustrate the performances of this approach, particularly in ambiguous situations

Appropriateness of inexpensive, hand-held global positioning system units for creating weed maps in a pasture

This paper describes the practical use of a global positioning system receiver (hand-held GPS) as a means of measuring and describing pasture areas invaded by weeds. The accuracy of two GPS units, a hand-held GPS with an external antenna (GPS with an antenna) and the differential global positioning system receiver (DGPS), were examined in Morioka, northern Japan. In addition, an area of weed patches and a pasture, determined using the GPS with an antenna, were compared to the measurements made with a conventional tape and a weed map was created based on the coordinate data of latitude and longitude measurements. The accuracy of the GPS with an antenna was poor (8.3 m); however, the precision of the unit was reasonable in measuring area. An area estimation error by the GPS with an antenna was 7% when practically measuring weed patches of 141 m2 and 1% in a paddock of 12 566 m2. From these results, it appears that the GPS with an antenna might have an acceptable error in measuring areas for weed control in a pasture. A weed map produced from the coordinate data surveyed using the GPS with an antenna enables the state of weed growth and its domination in an area of pasture to be visually understood. Therefore, GPS technologies easily can be applied to quickly obtain information on weed infestation.