Global Positioning System Coverage Research Articles

Cosmic time synchronizer (CTS) for wireless and precise time synchronization using extended air showers

Precise time synchronization is an essential technique required for financial transaction systems, industrial automation and control systems, as well as land and ocean observation networks. However, the time synchronization signals based on the global-positioning-system (GPS), or global-navigation-satellite-system, are sometimes unavailable or only partially available in indoor, underground and underwater environments. In this work, the simultaneous and penetrative natures of the muon component of the extended air shower (EAS) were used as signals for time synchronization in environments with little or no GPS coverage. CTS was modeled by combining the results of previous EAS experiments with OCXO holdover precision measurements. The results have shown the capability of CTS to reach perpetual local time synchronization levels of less than 100 ns with a hypothetical detector areal coverage of larger than 2 × 10−4. We anticipate this level of areal coverage is attainable and cost-effective for use in consumer smartphone networks and dense underwater sensor networks.

A Modified Anti-Jamming Method Using Dual-Polarized Ellipsoid Minimum Variance Distortionless Response to Predict the Coverage Ratio of Global Positioning System Signal

The dual-polarized array is considered as one of the key anti-jamming techniques due to twice counts of the jamming signals suppressed relative to a monopolar array. This paper proposes an adaptive anti-jamming dual-polarized ellipsoid minimum variance distortionless response (EMVDR) method to evaluate the carrier-to-noise ratio (<inline-formula> <tex-math notation="LaTeX">${C}$ </tex-math></inline-formula> a/<inline-formula> <tex-math notation="LaTeX">${N}_{{0}}$ </tex-math></inline-formula>) for global positioning system (GPS) coverage. Firstly in GPS L1 band, the dual-polarized gains obtained by controlled reception pattern antenna (CRPA) array are investigated as the signal model of GPS coverage evaluation. Secondly, a novel EMVDR method based the Hermitian tridiagonal loading technique is proposed to obtain the smooth anti-jamming weight matrix, which is against the system error by using the highpass filtering performance of Hermitian tridiagonal matrix. Finally, <inline-formula> <tex-math notation="LaTeX">${C}\text{a}/{N}_{{0}}$ </tex-math></inline-formula> based the proposed EMVDR is used to evaluate the coverage percentage of the GPS signal, namely <inline-formula> <tex-math notation="LaTeX">${C}\text{a}/{N}_{{0}}$ </tex-math></inline-formula> needs to be beyond a threshold of <inline-formula> <tex-math notation="LaTeX">$28~\text {dB}\cdot \text {Hz}$ </tex-math></inline-formula> by recovering GPS signal. Through many Monte Carlo simulations, the results indicate that the anti-jamming performance of proposed EMVDR method outperforms the classic minimum variance distortionless response (MVDR) based the space adaptive processing (SAP) and the space time adaptive processing (STAP), and the GPS coverage ratio can keep from 60&#x0025; to 70&#x0025; until degrees of freedom (DOFs) are exhausted to zero.

Identify association of appropriate technological application with per capita income of small scale fishing household - a case of Jaffna small scale fishing community, Srilanka

Fishing is vital not only for nutrition supplementary but also livelihood of millions of people. Uninterrupted supply of sufficient and quality fish stocks without affecting marine eco system is ideal for sustainability fishing. However, balancing between sustainability of marine ecosystem, market equilibrium and livelihood of fishing and fishing dependent community is a challenge. Technological application is one of approach to overcome the sustainability of fishing activities. Technological applications are diversified as 1) technology in fishing vessels, fishing gears, equipment and so on. 2) Technology application in information sharing and digital applications such as Global Positioning System (GPS), mobile phone application under Global System of Mobile Communication and 3) Technological application in fishing infrastructure such as cold room, transport equipment and so on. Small scale fishing community depends on labour intensive whereas large scale commercial fishing industries attribute on capital deepening. Adaptation of technology depends on several factors such as financial capability and technology know how. The study examined which technological application is appropriate to small scale fishing activities in Sri Lanka since 90 percent of fishing were carried out by small scale fishers (Fisheries Year Book 2018/19). Primary sample data were collected by structured interview from household level fishing community in Jaffna, North of Sri Lanka. Data were analyzed using descriptive and correlation statistical techniques. The study revealed that information technology especially application of GPS, Internet and mobile coverage in order to obtain fish catch and market information followed by digital sensor application in fishing gear had positive impact on maintain sustainable fishing catches of small-scale fishing activities. In addition, strict law enforcement and monitoring of poaching vessels such as Indian trawlers using radar technology with coordination of fisheries cooperative societies was an essential requirement of small-scale fishing community as external support with regard to sustain fishing stock of the region and their livelihood.

Multicommodity port throughput from truck GPS and lock performance data fusion

Inland waterways ports are key elements of an efficient multimodal freight transportation system. Data on the capacity and throughput of inland waterway ports by commodity support effective long-term freight planning and travel demand modeling. More specifically, such data can be used to estimate multimodal commodity-based freight fluidity performance measures and to support location selection for freight transload facilities. State-of-the-practice means of obtaining commodity flows data, such as shipper/carrier surveys and vessel and vehicle movements, are limited in their ability to provide monthly or seasonal statistics on individual port operations; rather, they provide annualized statistics for river segments which may contain multiple ports. These limitations are addressed herein by developing a multicommodity assignment model to quantify commodity throughput at inland waterways ports. The model fuses waterborne lock performance monitoring system data, which provides the commodity dimension, and anonymous truck Global Positioning System (GPS) data, which allows for spatial disaggregation. A goal-programming approach minimizes the deviation between known and estimated truck flows at each port. The methodology was applied to the Arkansas River, a 308-mile navigable waterway served by 14 locks and 43 freight ports. Overall, 84% of ports showed less than 20% difference between observed and predicted truck flows. The model is applicable to any inland waterways system with aggregated commodity flow data and truck GPS coverage and fills a critical data gap by describing commodity throughput at inland waterway ports using publicly available data.

An Efficient Integrated Attitude Determination Method Using Partially Available Doppler Measurement Under Weak GPS Environment

In this paper, we propose a new and efficient method to achieve a three dimensional attitude determination through combining the Doppler measurement with INS (Inertial Navigation System) in a partial GPS (Global Positioning System) coverage environment. First, equations associating raw measurement with user velocity vector and overall filter framework are introduced. Then, this paper presents formulation deriving a reference velocity incremental vector based on the Doppler measurement, which consequentially serve as the measurement of the attitude determination filter. In generating the reference velocity incremental vector, all three cases are taken into account according to the availability conditions of satellite. First, for three or more visible satellites case, a least square method is used to fix the user velocity vector; for other partial satellite cases, a reference velocity incremental vector is generated by devising the best geometric prediction from the respective satellite measurements. In order to verify the performance of this study, flight experiment is carried out with sensor equipment onboard a manned aircraft. For demonstrating the efficiency of the presented algorithm, we examined the proposed algorithm using the onboard flight experimental data. As a result of comparative study with a conventional tightly coupled integration method, the proposed method demonstrated competent performance in both accuracy and computational efficiency under partial satellite visibility.

A Zero-Configuration Tracking System for First Responders Networks

In emergency scenarios, tracking first responders is essential. While in open areas the quality of the Global Positioning System (GPS) service is typically acceptable, in partially obstructed environments, such as urban canyons, or indoor, it could be either unavailable or hindered by very coarse and unacceptable estimates. Moreover, most of the proposals for overcoming these limitations could be unsuitable in emergency scenarios. We propose a localization and tracking system based on the combined usage of WiFi and GPS. Essentially, when the GPS coverage is scarce, our localization solution allows augmenting it by using the WiFi access points as virtual satellites. When GPS coverage is not available at all, we use WiFi trilateration based on received signal strength, even maintaining the same coordinate system used in the GPS. The tracking protocol makes use of session initiation protocol messaging over a WiFi network. The proposed system is characterized by ease of deployment and usage, since it does not require any particular configuration. In order to assess its feasibility, we implemented a proof-of-concept prototype made up of low-cost commercial off-the-shelf components and open-source software. The performance tests carried out by using this prototype confirm the effectiveness of the proposed system.

Robotics research in Chile

The development of research in robotics in a developing country is a challenging task. Factors such as low research funds, low trust from local companies and the government, and a small number of qualified researchers hinder the development of strong, local research groups. In this article, and as a case of study, we present our research group in robotics at the Advanced Mining Technology Center of the Universidad de Chile, and the way in which we have addressed these challenges. In 2008, we decided to focus our research efforts in mining, which is the main industry in Chile. We observed that this industry has needs in terms of safety, productivity, operational continuity, and environmental care. All these needs could be addressed with robotics and automation technology. In a first stage, we concentrate ourselves in building capabilities in field robotics, starting with the automation of a commercial vehicle. An important outcome of this project was the earn of the local mining industry confidence. Then, in a second stage started in 2012, we began working with the local mining industry in technological projects. In this article, we describe three of the technological projects that we have developed with industry support: (i) an autonomous vehicle for mining environments without global positioning system coverage; (ii) the inspection of the irrigation flow in heap leach piles using unmanned aerial vehicles and thermal cameras; and (iii) an enhanced vision system for vehicle teleoperation in adverse climatic conditions.

A DSRC Doppler/IMU/GNSS Tightly-coupled Cooperative Positioning Method for Relative Positioning in VANETs

Relative position awareness is a vital premise for the implementation of emerging intelligent transportation systems. However, commercial Global Satellite Navigation Systems (GNSS) receivers do not satisfy the requirements of these applications. Fortunately, Cooperative Positioning (CP) systems, based on inter-vehicle communications, have improved performance of relative positioning in a Vehicular Ad Hoc Network (VANET). CP techniques rely primarily on measurements from the Global Positioning System (GPS) to deliver measurements or positions that describe the location of individual vehicles. In urban environments, the reduced quality or complete unavailability of GPS measurements challenges the effectiveness of any CP algorithm. In this paper, a new enhanced tightly–coupled CP technique is presented by adding the measurements from low-cost inertial sensors and the Doppler shift of the carrier of Dedicated Short-Range Communications (DSRC) signals. In the enhanced CP method proposed here, vehicles communicate their Inertial Measurement Unit (IMU) data and GPS measurements. Each vehicle fuses the GPS measurements and IMU data and the inter-node range-rates based on the Doppler shift of the carrier of DSRC signals. Based on analytical and experimental results, in a full GPS coverage environment, the new tight integration CP outperforms tight CP with Inertial Navigation System (INS), tight CP and differential GPS by at least by 6%, 15%, and 28%, respectively. In a GPS outage, the performance improvement can be up to 60%, 55%, and 66% respectively.

GPS signal accuracy and coverage analysis platform: Application to Trimble Juno SB receiver

Nowadays, information and mobile information technologies are being considered by the scientific community as primordial support for many other emerging technologies. The present paper exposes the results of a study and the analysis of accuracy, coverage and continuity of Global Positioning System (GPS) signal, using the Trimble Juno SB receiver. This is frequently used today for data collection and integration within Geographic Information Systems (GISs). Location-based services quality is highly depending on the accuracy of the position of the user. Generally, for each GPS enabled receiver the user need to evaluate the radius of the confidence region which describes the accuracy of the GPS device. In order to describe the accuracy of GPS receivers; a statistical method using a mobile software acquisition tool developed within our research group has been used. Intensive field measurements (i.e., 1data/1min x 3days) were carried out in Tetuan city (Morocco) during days of 29-30-31 May 2012 using local storage database feature. Homogeneous observation conditions and settings were respected for GPS signal acquisition. Finally, after calibrating the equipment, the results indicate that the Trimble Juno SB GPS receiver is well suited for services where meter accuracy is required.

Integration of infrastructure based positioning systems and inertial navigation for ubiquitous context-aware engineering applications

This paper presents research that investigated and implemented a hybrid integrated location tracking framework that was developed by integrating infrastructure based positioning systems and inertial navigation. The authors implemented this research by using the Personal Dead Reckoning positioning system to serve as the inertial navigation based positioning system. The primary contribution of the presented work is the development and implementation of the Integrated Tracking System algorithm which was implemented in two levels. At the first level, the Integrated Tracking System (ITS) was developed by integrating Global Positioning System (GPS) and Personal Dead Reckoning (PDR) system to ubiquitously track a mobile user, in dynamic environments where GPS coverage may be uncertain. At the second level, the PDR system was integrated with a database of pre-determined known indoor location points in order to correct the accumulated drift error during a mobile user’s navigation in an indoor environment. Finally, a hybrid tracking system was developed and implemented by integrating the PDR system with the mobile user’s intervention and discernment of the environment. The implementation and the results obtained from validation experiments performed on the aforementioned hybrid tracking systems demonstrate the potential of using hybrid tracking for determining the spatial context of mobile users in ubiquitous context-aware engineering applications.

Map‐aided localization in sparse global positioning system environments using vision and particle filtering

AbstractA map‐aided localization approach using vision, inertial sensors when available, and a particle filter is proposed and empirically evaluated. The approach, termed PosteriorPose, uses a Bayesian particle filter to augment global positioning system (GPS) and inertial navigation solutions with vision‐based measurements of nearby lanes and stop lines referenced against a known map of environmental features. These map‐relative measurements are shown to improve the quality of the navigation solution when GPS is available, and they are shown to keep the navigation solution converged in extended GPS blackouts. Measurements are incorporated with careful hypothesis testing and error modeling to account for non‐Gaussian and multimodal errors committed by GPS and vision‐based detection algorithms. Using a set of data collected with Cornell's autonomous car, including a measure of truth via a high‐precision differential corrections service, an experimental investigation of important design elements of the PosteriorPose estimator is conducted. The algorithm is shown to statistically outperform a tightly coupled GPS/inertial navigation solution both in full GPS coverage and in extended GPS blackouts. Statistical performance is also studied as a function of road type, filter likelihood models, bias models, and filter integrity tests. © 2011 Wiley Periodicals, Inc.

Autonomous Rule-Based Robot Navigation in Orchards

Orchard navigation using sensor-based localization and flexible mission management facilitates successful missions independent of the Global Positioning System (GPS). This is especially important while driving between tight tree rows where the GPS coverage is poor.This paper suggests localization based on an a priori map of the tree rows, a laser scanner based tree row detection, detecting both the row line and the row ends. The localization is combined with mission objectives in a rule-based inference interpreter. This rule-based mission handler combines the functional modules: localization, obstacle avoidance, path planning and drive control.The system is tested successfully using a Hako 20 kW tractor during autonomous missions in both cherry and apple orchards with mission length of up to 2.3 km including the headland turns.

Constraints on continued episodic inflation at Long Valley Caldera, based on seismic and geodetic observations

Long Valley Caldera, a large and potentially explosive silicic system, has experienced highly anomalous continued inflation since late 1970s. We characterize an episode of rapid episodic uplift occurring between 2002 and 2003 following similar episodes of 1979–1980, 1983, 1989–1990, and 1997–1998. This most recent episode was the first to be observed by a dense array of 13 continuous Global Positioning System (GPS) stations. Similar to previously observed episodes of deformation, uplift is quasi‐radially symmetric and is mostly explained by a compact pressure source located ∼3 km west of the resurgent dome. The maximum uplift during the 2002–2003 episode is ∼35 ± 8 mm, about 1/3 the magnitude but with a similar time‐dependent behavior as the 1997–1998 episode. The horizontal source location is well constrained at −118.930°, 37.678°, for a small spherical source, and indistinguishable from the location of a vertically dipping prolate spheroidal source. A trade‐off between depth and volume change is observed for both spherical and prolate models, with depth between 7.5 and 13.5 km and a volume change of 0.01–0.03 km3 at 95% confidence. For prolate spheroidal models, depth and volume change are additionally affected by the source axis ratio (b/a), which is greater than 0.55. Though the background seismicity remained low during the 2002–2003 episode, we identified a significant spike in activity during the maximum rate of uplift, similar to observations in both the much larger episodes in 1989–1990, and 1997–1998. More interestingly, we additionally find that all three episodes begin immediately after a short period of seismic quiescence, with background seismicity falling to levels below background levels following the prior uplift event. With the dense GPS coverage, we also identify increased opening of the Mono‐Inyo volcanic chain after the 2002–2003 episode suggesting potential interaction of magmatic fluids between the two systems.

Microplate model for the present‐day deformation of Tibet

Site velocities from 349 Global Positioning System (GPS) stations are used to construct an 11‐element quasi‐rigid block model of the Tibetan Plateau and its surroundings. Rigid rotations of five major blocks are well determined, and average translation velocities of six smaller blocks can be constrained. Where data are well distributed the velocity field can be explained well by rigid block motion and fault slip across block boundaries. Residual misfits average 1.6 mm/yr compared to typical one standard deviation velocity uncertainties of 1.3 mm/yr. Any residual internal straining of the blocks is small and heterogeneous. However, residual substructure might well represent currently unresolved motions of smaller blocks. Although any smaller blocks must move at nearly the same rate as the larger blocks within which they lie, undetected relative motions between them could be significant, particularly where there are gaps in GPS coverage. Predicted relative motions between major blocks agree with the observed sense of slip and along‐strike partitioning of motion across major faults. However, predicted slip rates across Tibet's major strike‐slip faults are low, only 5–12 mm/yr, a factor of 2–3 smaller than most rates estimated from fault offset features dated by radiometric methods as ∼2000 to ∼100,000 year old. Previous work has suggested that both GPS data and low fault slip rates are incompatible with rigid block motions of Tibet. The results reported here overcome these objections.

Power Matching Approach for GPS Coverage Extension

The inherent problem of the Global Positioning System (GPS), which is signal obstruction, remains the major obstacle that inhibits it from functioning as a reliable stand-alone positioning system. Therefore, it is becoming a common practice to couple the GPS system with an external positioning system whenever the GPS receiver is expected to operate in regions of dense canopy, such as urban areas. Commercial automobile navigation systems currently employ a GPS receiver coupled with a dead reckoning (DR) system and a map-matching algorithm. Most DR systems, which compensate for GPS inaccuracies and frequent GPS signal obstructions, employ an odometer and a directional sensor. In this paper, a power matching approach is proposed for GPS coverage extension in urban area. The algorithm, based on a statistical measure, correlates the received power from different GPS satellite vehicles (SVs), which leads to a specific signature, i.e., to a topographical database with periodic time-varying estimates of the received powers of SVs. An experimental approach is presented to examine the feasibility of applying the proposed positioning system.