US Global Positioning System Research Articles

Practitioner Usage, Applications, and Understanding of Wearable GPS and Accelerometer Technology in Team Sports.

Dawson, L, McErlain-Naylor, SA, Devereux, G, and Beato, M. Practitioner usage, applications, and understanding of wearable GPS and accelerometer technology in team sports. J Strength Cond Res 38(7): e373-e382, 2024-Monitoring training load is essential for optimizing the performance of athletes, allowing practitioners to assess training programs, monitor athlete progress, and minimize the risk of injury and overtraining. However, there is no universal method for training load monitoring, and the adoption of wearable global positioning system (GPS) and accelerometer technology in team sports has increased the volume of data and, therefore, the number of possible approaches. This survey investigated the usage, applications, and understanding of this technology by team sports practitioners. Seventy-two practitioners involved in team and athlete performance monitoring using GPS and accelerometer technology completed the survey. All respondents reported supporting the use of GPS technology in their sport, with 70.8% feeling that GPS technology is important for success. Results showed that 87.5% of respondents use data from wearable technology to inform training prescription, although only 50% use the data to influence decisions in competition. In addition, results showed that GPS metrics are used more than accelerometer-derived metrics; however, both are used regularly. Discrepancies in accelerometer usage highlighted concerns about practitioners' understanding of accelerometer-derived metrics. This survey gained insight into usage, application, understanding, practitioner needs, and concerns and criticisms surrounding the use of GPS and accelerometer metrics for athlete load monitoring. Such information can be used to improve the implementation of this technology in team sport monitoring and highlight gaps in the literature that will help to design future studies to support practitioner needs.

Systematic review of best practices for GPS data usage, processing, and linkage in health, exposure science and environmental context research

Global Positioning System (GPS) technology is increasingly used in health research to capture individual mobility and contextual and environmental exposures. However, the tools, techniques and decisions for using GPS data...

Force-torque (F-T) based multi-drone cooperative transport using fuzzy logic and low-cost and imprecise F-T sensor

This paper presents a novel approach to perform the task of cooperative transportation (CT) by using multiple quadcopter drones. A leader-follower approach is utilized. Considering that the leader drone can be controlled using different means, such as Proportional, Integral, and Derivative (PID) control or remote control by an operator, this paper focuses on designing the control scheme for the follower drone. This paper specifically considers outdoor application of such systems that requires usage of Global Positioning System (GPS) to receive the positional information of the drones. However, GPS has inherent errors of order of magnitude that can destabilize the system. In order to address this major limitation, a Force-Torque Feedback Controller (FT-FC) is proposed to control the follower drone. The FT-FC provides control based on the interaction forces and torques acting at the point of contact between the follower drone and the payload. Using such passive control schemes, drones are thus not required to communicate with each other. Fuzzy Logic (FL) is used to implement the FT-FC. Fuzzy Logic provides effective force-torque coordination between drones, emulates human behavior during CT, and allows use of noisy inexpensive force-torque sensors. This paper presents results from numerical simulations showing the effectiveness of the proposed controller for way-point navigation and complex trajectory tracking. Additionally, the effectiveness of the fuzzy-based FT-FC in terms of handling disturbances is also demonstrated. The proposed FL FT-FC is also experimentally validated for two applications viz. three-dimensional physical Human Drone Interaction (HDI) and CT.

Experimental evaluation of using BLE beacon for outdoor positioning in GPS-denied environment

Abstract. Although Global Positioning System (GPS) is widely used in outdoor location-based services, it still lacks precision due to obstacles that reduce its performance, such as near tall buildings, with bad weather conditions, and under tree canopies. In some situations, inaccurate localization or delay in getting location locks can adversely affect some location-based services’ functionality. Furthermore, it might make these services less efficient or even completely useless, especially when the receiver device has no SIM card or when the service requires a precision higher than three meters. As a solution to this issue, this study designs, develops, and evaluates a prototype location-based system that uses Bluetooth Low Energy beacons for short-range positioning in outdoor environments as a GPS alternative. The proposed system is a game that includes navigational tasks, which can be accomplished by reaching the proximity of two meters from the beacon’s location. The study involved conducting an experiment outdoors with a focus on areas where GPS signals are degraded to assess our proposed system’s efficiency and feasibility compared to the usage of GPS. The results proved BLE beacons’ ability to provide better positioning results than GPS, not only in terms of accuracy but also in terms of stability of positioning results over time. Based on the findings, the study outlines a set of guidelines to be considered in choosing a suitable positioning technology.

Auto-detection of sporadic E and spread F events from the digital ionograms

To evaluate huge ionogram datasets and detect ionosphere variabilities, automatic identification of Sporadic E (Es) and Spread F (SF) events in digital ionograms is required. This work presents an auto-detection technique to identify the ionograms' Es and SF signatures. Es and SF events are detected automatically by de-noising the ionogram, segmentation, and quantifying the frequency and height points in each layer segmented part. The technique's performance is assessed using ionograms acquired by the Canadian Advanced Digital Ionosonde (CADI) at a low latitude station in Hyderabad, India, in 2015. With a detection efficiency of 96.71%, 89.71%, and 93.39%, the suggested technique successfully detected the Es, Range Spread F (RSF), and Strong Spread F (SSF) events from ionograms. To demonstrate the correlation between SSF and S4, the occurrence rate of SSF is compared to the amplitude scintillation (S4) rate of the Global Positioning System (GPS). The recommended technique is useful for launching ionospheric alert systems for high-frequency communications and GPS users.

Performance Assessment of Real-Time Multiconstellation GNSS PPP Using a Low-Cost Dual-Frequency GNSS Module

Abstract The release of low-cost dual-frequency (DF) global navigation satellite system (GNSS) modules provides an opportunity for low-cost precise positioning to support autonomous vehicle applications. The new GNSS modules support the US global positioning system (GPS) L1C/L2C or L5 civilian signals, the Russian GNSS Globalnaya Navigazionnaya Sputnikovaya Sistema (GLONASS) L1/L2, Europe’s GNSS Galileo E1/E5b, and Chinese GNSS BeiDou B1/B2 signals. The availability of the DF measurements allows for removal of the ionospheric delay, enhancing the obtained positioning accuracy. Unfortunately, however, the L2C signals are only transmitted by modernized GPS satellites. This means that fewer GPS DF measurements are available. This, in turn, might affect the accuracy and the convergence of the GPS-only precise point positioning (PPP) solution. Multi-constellation GNSS PPP has the potential to improve the positioning accuracy and solution convergence due to the high redundancy of GNSS measurements. This paper aims to assess the performance of real-time quad-constellation GNSS PPP using the low-cost u-blox Z9D-F9P module. The assessment is carried out for both open-sky and challenging environment scenarios. Static, simulated-kinematic, and actual field-kinematic trials have been carried out to evaluate real-time PPP performance. Pre-saved real-time precise orbit and clock products from the Centre National d’Etudes Spatiales are used to simulate the real-time scenario. It is shown that the quad-constellation GNSS PPP using the low-cost u-blox Z9D-F9P module achieves decimeter-level positioning accuracy in both the static and simulated-kinematic modes. In addition, the PPP solution convergence is improved compared to the dual- and triple-constellation GNSS PPP counterparts. For the actual kinematic trial, decimeter-level horizontal positioning accuracy is achieved through the GPS + GLONASS + Galileo PPP compared with submeter-level positioning accuracy for the GPS + GLONASS and GPS + Galileo PPP counterparts. Additionally, submeter-level vertical positioning accuracy is achieved through the GPS + GLONASS + Galileo PPP compared with meter-level positioning accuracy for GPS + GLONASS and GPS + Galileo PPP counterparts.

Behavioral Correlates of GPS Device Usage Among Small-Scale Fishers in Malaysia

This article aims to examine the relationship between selected behavioral factors and Global Positioning System (GPS) usage among small-scale fishers in Malaysia. An adapted version of the Unified Theory of Acceptance and Use of Technology (UTAUT) was tested among a sample of 400 small-scale fishers to examine the relationship between technology-related behavioral constructs (compatibility, social influence, effort expectancy, learning culture, and performance expectancy) and GPS usage. The sample was selected from 12 fishery districts in Malaysia. Confirmatory factor analysis (CFA) confirmed that all five technology-related behavioral constructs included in the model recorded a significant relationship with GPS usage. The results extend the generalizability of the UTAUT to a previously understudied setting of community technology usage. Understanding GPS usage among small-scale fishers from the extended UTAUT perspective can provide policy makers, public, nongovernmental organizations (NGOs), and other concerned parties with knowledge that can build awareness and shape capacity building efforts for small-scale interventions to increase the use of GPS. This will, in turn, reduce the risks associated with fishing routines and enhance fishing yields.

Evaluation of Ionospheric Delays Based on Orthogonal Dimensionality Reduction Approach

The effect of space weather on Global Positioning System (GPS) signals transmitted through the ionosphere is a significant cause of range errors and can be vulnerable to GPS users. Accurate evaluation of ionospheric delays plays an essential role in improving the navigation service in the position domain for Category I (CAT I) operations. In this paper, an attempt is made to estimate the ionospheric delays based on the Spherical Harmonic Function (SHF) model using the Singular Value Decomposition (SVD) approach. Total Electron Content (TEC) data from 17 GPS stations were considered in this analysis and operate under the GPS–Aided Geo Augmented Navigation (GAGAN) network in the Indian region. The results show that the SVD–SHF approach is more efficient in estimating ionospheric delays than the Weighted Least Square (WLS) method. Due to the rapid convergence of the SVD, the first five singular values of the geometric matrix (H) can be used to represent the total variance. The average Root Mean Square Error (RMSE) and Mean Absolute Error (MAE) deviations of (WLS–SHF) are 0.75 m and 0.61 m, and the corresponding deviations of SVD–SHF are 0.71 m and 0.59 m were recorded during the storm period 26 to 28 July 2004 (Dst = −170 nT). The computational load for modeling the ionosphere delays with the WLS–SHF model is 15.48 s and the corresponding load for SVD–SHF is 3.81 s. The proposed solution is numerically stable, requires less computation time, reduces the data dimensions, and round–off errors in initial data. The proposed algorithm can be implemented in Global Navigation Satellite System (GNSS) and surveying applications.

Bridge Inspection Using Unmanned Aerial Vehicle Based on HG-SLAM: Hierarchical Graph-Based SLAM

With the increasing demand for autonomous systems in the field of inspection, the use of unmanned aerial vehicles (UAVs) to replace human labor is becoming more frequent. However, the Global Positioning System (GPS) signal is usually denied in environments near or under bridges, which makes the manual operation of a UAV difficult and unreliable in these areas. This paper addresses a novel hierarchical graph-based simultaneous localization and mapping (SLAM) method for fully autonomous bridge inspection using an aerial vehicle, as well as a technical method for UAV control for actually conducting bridge inspections. Due to the harsh environment involved and the corresponding limitations on GPS usage, a graph-based SLAM approach using a tilted 3D LiDAR (Light Detection and Ranging) and a monocular camera to localize the UAV and map the target bridge is proposed. Each visual-inertial state estimate and the corresponding LiDAR sweep are combined into a single subnode. These subnodes make up a “supernode” that consists of state estimations and accumulated scan data for robust and stable node generation in graph SLAM. The constraints are generated from LiDAR data using the normal distribution transform (NDT) and generalized iterative closest point (G-ICP) matching. The feasibility of the proposed method was verified on two different types of bridges: on the ground and offshore.

IONOSPHERIC ANOMALY DETECTION ALGORITHM USING AAD TECHNIQUE

In this paper, Autonomous Anomaly Detection (AAD) is implemented for detecting ionospheric irregularities from ground based Global Positioning System (GPS) observations. EDA isbased on the ensemble properties and mutual distribution of the empirical discrete observations gives that classification and anomaly detection are autonomous,self-organizing,data driven and free from user and problem specific parameters.Ionospheric code and carrier phase measurements recorded by Navigation with Indian Constellation (NAVIC) receiver located at Guntur, India is considered. The code minus carrier phase measurements are tested with proposed AAD technique. It is found that AAD technique is capable to capture ionospheric anomalies in NAVIC L and S band signals. The outcome of this work would be useful for improving positional accuracy of GPS users.

NaviSoC: High-Accuracy Low-Power GNSS SoC with an Integrated Application Processor

A dual-frequency all-in-one Global Navigation Satellite System (GNSS) receiver with a multi-core 32-bit RISC (reduced instruction set computing) application processor was integrated and manufactured as a System-on-Chip (SoC) in a 110 nm CMOS (complementary metal-oxide semiconductor) process. The GNSS RF (radio frequency) front-end with baseband navigation engine is able to receive, simultaneously, Galileo (European Global Satellite Navigation System) E1/E5ab, GPS (US Global Positioning System) L1/L1C/L5, BeiDou (Chinese Navigation Satellite System) B1/B2, GLONASS (GLObal NAvigation Satellite System of Russian Government) L1/L3/L5, QZSS (Quasi-Zenith Satellite System development by the Japanese government) L1/L5 and IRNSS (Indian Regional Navigation Satellite System) L5, as well as all SBAS (Satellite Based Augmentation System) signals. The ability of the GNSS to detect such a broad range of signals allows for high-accuracy positioning. The whole SoC (system-on-chip), which is connected to a small passive antenna, provides precise position, velocity and time or raw GNSS data for hybridization with the IMU (inertial measurement unit) without the need for an external application processor. Additionally, user application can be executed directly in the SoC. It works in the −40 to +105 °C temperature range with a 1.5 V supply. The assembled test-chip takes 100 pins in a QFN (quad-flat no-leads) package and needs only a quartz crystal for the on-chip reference clock driver and optional SAW (surface acoustic wave) filters. The radio performance for both wideband (52 MHz) channels centered at L1/E1 and L5/E5 is NF = 2.3 dB, G = 131 dB, with 121 dBc/Hz of phase noise @ 1 MHz offset from the carrier, consumes 35 mW and occupies a 4.5 mm2 silicon area. The SoC reported in the paper is the first ever dual-frequency single-chip GNSS receiver equipped with a multi-core application microcontroller integrated with embedded flash memory for the user application program.

Low Latitude Ionosphere Error Correction Algorithms for Global Navigation Satellite System

The ionospheric errors occur due to loss of data in ionospheric region. Low latitudinal regions are the most affected regions due to ionospheric errors and also causes loss of signal or data for space based augmentation system(SBAS) such as aircraft. So to reduce these ionospheric errors in low latitude regions of Global Navigation Satellite System(GNSS) Klobuchar algorithm is used which mitigates the errors occurring in low latitude regions and is used as a standard algorithm in US Global Positioning System(GPS) till now; however, this model can reduce the ionospheric error by approximately 50-60% Root Mean Square(RMS) error in low-latitudes. So in order to increase the percentage deviation of errors in low-latitude regions, Enhanced Klobuchar algorithm is proposed which enhances the correction of low-latitude ionospheric errors approximately up to 80% RMS for a single frequency GPS user. In this paper error correction algorithms are performed over International GPS Service(IGS) data was collected using Hyderabad station receiver, Telangana (latitude- 17.41728°, longitude-78.55088°) in southern part of India during year 2016.

Computing GPS satellite velocity and acceleration from the broadcast navigation message

We present an extension to the Global Positioning System (GPS) broadcast navigation message user equations for computing GPS space vehicle (SV) velocity and acceleration. Although similar extensions have been published, the extension presented herein includes a distinct kinematic method for computing SV acceleration, which significantly reduces the complexity of the equations and improves the mean magnitude results by approximately one order of magnitude by including oblate Earth perturbation effects. Additionally, detailed analyses and validation results using multiple days of precise ephemeris data and multiple broadcast navigation messages are presented. Improvements in the equations for computing SV position are also included, removing ambiguity and redundancy in the existing user equations. The recommended changes make the user equations more complete and more suitable for implementation in a wide variety of programming languages employed by GPS users. Furthermore, relativistic SV clock error rate computation is enabled by the recommended equations. A complete, stand-alone table of the equations in the format and notation of the GPS interface specification is provided, along with benchmark test cases to simplify implementation and verification.

Software-Defined Radio GNSS Instrumentation for Spoofing Mitigation: A Review and a Case Study

Recently, several global navigation satellite systems (GNSS) emerged following the transformative technology impact of the first GNSS: US Global Positioning System (GPS). The power level of GNSS signals as measured at the earths surface is below the noise floor and is consequently vulnerable against interference. Spoofers are smart GNSS-like interferers, which mislead the receivers into generating false position and time information. While many spoofing mitigation techniques exist, spoofers are continually evolving, producing a cycle of new spoofing attacks and counter-measures against them. Thus, upgradability of receivers becomes an important advantage for maintaining their immunity against spoofing. Software-defined radio (SDR) implementations of a GPS receiver address such flexibility but are challenged by demanding computational requirements of both GNSS signal processing and spoofing mitigation. Therefore, this paper reviews reported SDRs in the context of instrumentation capabilities for both conventional and spoofing mitigation modes. This separation is necessitated by significantly increased computational loads when in spoofing domain. This is demonstrated by a case study budget analysis.

Development of GPS Positioning and Navigation Software System Based on VC++

With the rapid development of China’s economy, the field positioning and navigation technology has also been continuously developed. The global positioning system(GPS), can provide fast and accurate positioning and navigation for exploration operations in desert areas. In this paper, the developed GPS navigation and positioning software system solves the problem of cooperation between GPS user terminal equipment and exploration site. It also effectively combines image processing, data transmission, data processing, error analysis and other technologies to achieve the goals such as data recording and transmission, field navigation, data browsing and query, coordinate transformation, error analysis, and printing curve. After field test work and post-data processing, the software proved to have the following advantages: convenient operation, accurate coordinate transformation and complete functions. It could meet the requirements for accurate GPS positioning and navigation of the field exploration. Its practical effect is good and can provide reference for future field exploration and navigation mapping.

On the Study of Influences of Different Factors on the Rapid Tropospheric Tomography

A rapid tropospheric tomography system was developed by using algebraicreconstruction technique. Influences of different factors on the tomographic results, including theground meteorological data, the multi-Global Navigation Satellite System (GNSS) observations, theground station distribution and the tomographic horizontal resolution, were systematicallyinvestigated. In order to exclude the impacts from discrepancies of water vapor informationbetween input observations and references on the tomographic results, the latest reanalysisproducts, ERA5, which were taken as references for result evaluations, were used to simulate slantwet delay (SWD) observations at GNSS stations. Besides, the slant delays derived from GNSSprocessing were also used to evaluate the reliability of simulated observations. Tomography resultsshow that the input both SWD and ground meteorological data could improve the tomographicresults where SWD mainly improve the results at middle layers (500 to 5000m, namely 2 to 16 layer)and ground meteorological data could improve the humidity fields at bottom layers further (0 to500m, namely 0 to 2 layer). Compared to the usage of Global Positioning System (GPS) only SWD,the inclusion of multi-GNSS SWD does not significantly improve the tomographic results at alllayers due to the almost unchanged dispersion of puncture points of GNSS signals. However,increases in the ground GNSS stations can benefit the tomography, with improvements of morethan 10% at bottom and middle layers. Higher tomographic horizontal resolution can furtherslightly improve the tomographic results (about 3-6% from 0.5 to 0.25 degrees), which, however,will also increase the computational burden at the same time.

Performance Evaluation of the CNAV Broadcast Ephemeris

The new Global Positioning System (GPS) Civil Navigation Message (CNAV) has been transmitted by Block IIR-M and Block IIF satellites since April 2014, both on the L2C and L5 signals. Compared to the Legacy Navigation Message (LNAV), the CNAV message provides six additional parameters (two orbit parameters and four Inter-Signal Correction (ISC) parameters) for prospective civil users. Using the precise products of the International Global Navigation Satellite System Service (IGS), we evaluate the precision of satellite orbit, clock and ISCs of the CNAV. Additionally, the contribution of the six new parameters to GPS Single Point Positioning (SPP) is analysed using data from 22 selected Multi-Global Navigation Satellite System Experiment (MGEX) stations from a 30-day period. The results indicate that the CNAV/LNAV Signal-In-Space Range Error (SISRE) and orbit-only SISRE from January 2016 to March 2018 is of 0·5 m and 0·3 m respectively, which is improved in comparison with the results from an earlier period. The ISC precision of L1 Coarse/Acquisition (C/A) is better than 0·1 ns, and those of L2C and L5Q5 are about 0·4 ns. Remarkably, ISC correction has little effect on the single-frequency SPP for GPS users using civil signals (for example, L1C, L2C), whereas dual-frequency SPP with the consideration of ISCs results have an accuracy improvement of 18·6%, which is comparable with positioning accuracy based on an ionosphere-free combination of the L1P (Y) and L2P (Y) signals.

Factors linked with adaptation in the Indian marine fishing community

Understanding the factors associated with adaptation can be crucial for building community adaptive-capacity. This study aims to provide a country-level assessment of some of the factors driving adaptation responses in marine fishing, and is based on data from 2564 villages and 66 districts along the coastline of India. Mechanization, usage of Global Positioning System (GPS) and diversification are important adaptation responses in the community. This study employs an analytical framework to understand three types of factors influencing adaptation: vulnerability/risk, difference in the macro environment and community-level factors (human, economic and social capitals, such as education, poverty and cooperative membership). The results indicate that the different factors are not uniformly associated with the adaptation responses. Regions which are vulnerable and face greater cyclone risk have low adaptation. The macro-environment of the state as well as support through cooperatives can play a role in adaptation. The results also highlight the importance of higher levels of education for adaptation responses, such as, using advanced navigation technology (GPS) and diversifying into other professions. The study provides useful insights regarding the factors linked with adaptation responses in the community and can be helpful for designing interventions. The paper can complement findings from regional studies and emphasizes the need for future rigorous research on adaptation in marine fishing.

Calibration errors in determining slant Total Electron Content (TEC) from multi-GNSS data

The global navigation satellite system (GNSS) is presently a powerful tool for sensing the Earth's ionosphere. For this purpose, the ionospheric measurements (IMs), which are by definition slant total electron content biased by satellite and receiver differential code biases (DCBs), need to be first extracted from GNSS data and then used as inputs for further ionospheric representations such as tomography. By using the customary phase-to-code leveling procedure, this research comparatively evaluates the calibration errors on experimental IMs obtained from three GNSS, namely the US Global Positioning System (GPS), the Chinese BeiDou Navigation Satellite System (BDS), and the European Galileo. On the basis of ten days of dual-frequency, triple-GNSS observations collected from eight co-located ground receivers that independently form short-baselines and zero-baselines, the IMs are determined for each receiver for all tracked satellites and then for each satellite differenced for each baseline to evaluate their calibration errors. As first derived from the short-baseline analysis, the effects of calibration errors on IMs range, in total electron content units, from 1.58 to 2.16, 0.70 to 1.87, and 1.13 to 1.56 for GPS, Galileo, and BDS, respectively. Additionally, for short-baseline experiment, it is shown that the code multipath effect accounts for their main budget. Sidereal periodicity is found in single-differenced (SD) IMs for GPS and BDS geostationary satellites, and the correlation of SD IMs over two consecutive days achieves the maximum value when the time tag is around 4 min. Moreover, as byproducts of zero-baseline analysis, daily between-receiver DCBs for GPS are subject to more significant intra-day variations than those for BDS and Galileo.

Static and kinematic positioning performance of a low-cost real-time kinematic navigation system module

To investigate the static and kinematic positioning performance with the low-cost multiple Global Navigation Satellite System (GNSS) receivers is vital for the GNSS community owing to their wide civil applications. In this contribution, we developed the real-time kinematic (RTK) algorithms for low-cost GNSS receiving module to fulfil the task of the integrated RTK positioning with US Global Positioning System (GPS) and the Chinese BeiDou Navigation Satellite System (BDS). The RTK positioning performance of a low-cost module named STA8090 and a state-of-the-art module named Novatel OEM6 was compared. In our study, the virtual reference station (VRS) data stream from QianXun SI was utilized. First, one 12-h static test was performed, achieving the centimeter-level horizontal accuracy with an RMS (Root Mean Square) of less than 1 cm. Afterwards, some kinematic experiments were conducted under four different environmental scenarios, of which positioning accuracy of approximately 20 cm was obtained. The experimental results demonstrated that the RTK positioning performance with low-cost multi-GNSS module can fulfil the current navigation capability well.