Performance evaluation of GPS receiver under equatorial scintillation

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Alison de Oliveira Moraes

2009-06-01

Full Text Available Equatorial scintillation is a phenomenon that occurs daily in the equatorial region after the sunset and affects radio signals that propagate through the ionosphere. Depending on the temporal and spatial situation, equatorial scintillation can represent a problem in the availability and precision of the Global Positioning System (GPS. This work is concerned with evaluating the impact of equatorial scintillation on the performance of GPS receivers. First, the morphology and statistical model of equatorial scintillation is briefly presented. A numerical model that generates synthetic scintillation data to simulate the effects of equatorial scintillation is presented. An overview of the main theoretical principles on GPS receivers is presented. The analytical models that describe the effects of scintillation at receiver level are presented and compared with numerical simulations using a radio software receiver and synthetic data. The results achieved by simulation agreed quite well with those predicted by the analytical models. The only exception is for links with extreme levels of scintillation and when weak signals are received.

Performance Enhancement of Land Vehicle Positioning Using Multiple GPS Receivers in an Urban Area

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Jong-Hwa Song

2016-10-01

Full Text Available The Global Positioning System (GPS is the most widely used navigation system in land vehicle applications. In urban areas, the GPS suffers from insufficient signal strength, multipath propagation and non-line-of-sight (NLOS errors, so it thus becomes difficult to obtain accurate and reliable position information. In this paper, an integration algorithm for multiple receivers is proposed to enhance the positioning performance of GPS for land vehicles in urban areas. The pseudoranges of multiple receivers are integrated based on a tightly coupled approach, and erroneous measurements are detected by testing the closeness of the pseudoranges. In order to fairly compare the pseudoranges, GPS errors and terms arising due to the differences between the positions of the receivers need to be compensated. The double-difference technique is used to eliminate GPS errors in the pseudoranges, and the geometrical distance is corrected by projecting the baseline vector between pairs of receivers. In order to test and analyze the proposed algorithm, an experiment involving live data was performed. The positioning performance of the algorithm was compared with that of the receiver autonomous integrity monitoring (RAIM-based integration algorithm for multiple receivers. The test results showed that the proposed algorithm yields more accurate position information in urban areas.

Performance Analysis of Constrained Loosely Coupled GPS/INS Integration Solutions

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Fabio Dovis

2012-11-01

Full Text Available The paper investigates approaches for loosely coupled GPS/INS integration. Error performance is calculated using a reference trajectory. A performance improvement can be obtained by exploiting additional map information (for example, a road boundary. A constrained solution has been developed and its performance compared with an unconstrained one. The case of GPS outages is also investigated showing how a Kalman filter that operates on the last received GPS position and velocity measurements provides a performance benefit. Results are obtained by means of simulation studies and real data.

Performance Analysis of Several GPS/Galileo Precise Point Positioning Models.

Science.gov (United States)

Afifi, Akram; El-Rabbany, Ahmed

2015-06-19

This paper examines the performance of several precise point positioning (PPP) models, which combine dual-frequency GPS/Galileo observations in the un-differenced and between-satellite single-difference (BSSD) modes. These include the traditional un-differenced model, the decoupled clock model, the semi-decoupled clock model, and the between-satellite single-difference model. We take advantage of the IGS-MGEX network products to correct for the satellite differential code biases and the orbital and satellite clock errors. Natural Resources Canada's GPSPace PPP software is modified to handle the various GPS/Galileo PPP models. A total of six data sets of GPS and Galileo observations at six IGS stations are processed to examine the performance of the various PPP models. It is shown that the traditional un-differenced GPS/Galileo PPP model, the GPS decoupled clock model, and the semi-decoupled clock GPS/Galileo PPP model improve the convergence time by about 25% in comparison with the un-differenced GPS-only model. In addition, the semi-decoupled GPS/Galileo PPP model improves the solution precision by about 25% compared to the traditional un-differenced GPS/Galileo PPP model. Moreover, the BSSD GPS/Galileo PPP model improves the solution convergence time by about 50%, in comparison with the un-differenced GPS PPP model, regardless of the type of BSSD combination used. As well, the BSSD model improves the precision of the estimated parameters by about 50% and 25% when the loose and the tight combinations are used, respectively, in comparison with the un-differenced GPS-only model. Comparable results are obtained through the tight combination when either a GPS or a Galileo satellite is selected as a reference.

Positioning performance of the NTCM model driven by GPS Klobuchar model parameters

Science.gov (United States)

Hoque, Mohammed Mainul; Jakowski, Norbert; Berdermann, Jens

2018-03-01

Users of the Global Positioning System (GPS) utilize the Ionospheric Correction Algorithm (ICA) also known as Klobuchar model for correcting ionospheric signal delay or range error. Recently, we developed an ionosphere correction algorithm called NTCM-Klobpar model for single frequency GNSS applications. The model is driven by a parameter computed from GPS Klobuchar model and consecutively can be used instead of the GPS Klobuchar model for ionospheric corrections. In the presented work we compare the positioning solutions obtained using NTCM-Klobpar with those using the Klobuchar model. Our investigation using worldwide ground GPS data from a quiet and a perturbed ionospheric and geomagnetic activity period of 17 days each shows that the 24-hour prediction performance of the NTCM-Klobpar is better than the GPS Klobuchar model in global average. The root mean squared deviation of the 3D position errors are found to be about 0.24 and 0.45 m less for the NTCM-Klobpar compared to the GPS Klobuchar model during quiet and perturbed condition, respectively. The presented algorithm has the potential to continuously improve the accuracy of GPS single frequency mass market devices with only little software modification.

Accurate Localization of Communicant Vehicles using GPS and Vision Systems

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Georges CHALLITA

2009-07-01

Full Text Available The new generation of ADAS systems based on cooperation between vehicles can offer serious perspectives to the road security. The inter-vehicle cooperation is made possible thanks to the revolution in the wireless mobile ad hoc network. In this paper, we will develop a system that will minimize the imprecision of the GPS used to car tracking, based on the data given by the GPS which means the coordinates and speed in addition to the use of the vision data that will be collected from the loading system in the vehicle (camera and processor. Localization information can be exchanged between the vehicles through a wireless communication device. The creation of the system must adopt the Monte Carlo Method or what we call a particle filter for the treatment of the GPS data and vision data. An experimental study of this system is performed on our fleet of experimental communicating vehicles.

Fuzzy adaptive integration scheme for low-cost SINS/GPS navigation system

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Nourmohammadi, Hossein; Keighobadi, Jafar

2018-01-01

Due to weak stand-alone accuracy as well as poor run-to-run stability of micro-electro mechanical system (MEMS)-based inertial sensors, special approaches are required to integrate low-cost strap-down inertial navigation system (SINS) with global positioning system (GPS), particularly in long-term applications. This paper aims to enhance long-term performance of conventional SINS/GPS navigation systems using a fuzzy adaptive integration scheme. The main concept behind the proposed adaptive integration is the good performance of attitude-heading reference system (AHRS) in low-accelerated motions and its degradation in maneuvered or accelerated motions. Depending on vehicle maneuvers, gravity-based attitude angles can be intelligently utilized to improve orientation estimation in the SINS. Knowledge-based fuzzy inference system is developed for decision-making between the AHRS and the SINS according to vehicle maneuvering conditions. Inertial measurements are the main input data of the fuzzy system to determine the maneuvering level during the vehicle motions. Accordingly, appropriate weighting coefficients are produced to combine the SINS/GPS and the AHRS, efficiently. The assessment of the proposed integrated navigation system is conducted via real data in airborne tests.

Implementation and Performance of a GPS/INS Tightly Coupled Assisted PLL Architecture Using MEMS Inertial Sensors

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Youssef Tawk

2014-02-01

Full Text Available The use of global navigation satellite system receivers for navigation still presents many challenges in urban canyon and indoor environments, where satellite availability is typically reduced and received signals are attenuated. To improve the navigation performance in such environments, several enhancement methods can be implemented. For instance, external aid provided through coupling with other sensors has proven to contribute substantially to enhancing navigation performance and robustness. Within this context, coupling a very simple GPS receiver with an Inertial Navigation System (INS based on low-cost micro-electro-mechanical systems (MEMS inertial sensors is considered in this paper. In particular, we propose a GPS/INS Tightly Coupled Assisted PLL (TCAPLL architecture, and present most of the associated challenges that need to be addressed when dealing with very-low-performance MEMS inertial sensors. In addition, we propose a data monitoring system in charge of checking the quality of the measurement flow in the architecture. The implementation of the TCAPLL is discussed in detail, and its performance under different scenarios is assessed. Finally, the architecture is evaluated through a test campaign using a vehicle that is driven in urban environments, with the purpose of highlighting the pros and cons of combining MEMS inertial sensors with GPS over GPS alone.

Implementation and Performance of a GPS/INS Tightly Coupled Assisted PLL Architecture Using MEMS Inertial Sensors

Science.gov (United States)

Tawk, Youssef; Tomé, Phillip; Botteron, Cyril; Stebler, Yannick; Farine, Pierre-André

2014-01-01

The use of global navigation satellite system receivers for navigation still presents many challenges in urban canyon and indoor environments, where satellite availability is typically reduced and received signals are attenuated. To improve the navigation performance in such environments, several enhancement methods can be implemented. For instance, external aid provided through coupling with other sensors has proven to contribute substantially to enhancing navigation performance and robustness. Within this context, coupling a very simple GPS receiver with an Inertial Navigation System (INS) based on low-cost micro-electro-mechanical systems (MEMS) inertial sensors is considered in this paper. In particular, we propose a GPS/INS Tightly Coupled Assisted PLL (TCAPLL) architecture, and present most of the associated challenges that need to be addressed when dealing with very-low-performance MEMS inertial sensors. In addition, we propose a data monitoring system in charge of checking the quality of the measurement flow in the architecture. The implementation of the TCAPLL is discussed in detail, and its performance under different scenarios is assessed. Finally, the architecture is evaluated through a test campaign using a vehicle that is driven in urban environments, with the purpose of highlighting the pros and cons of combining MEMS inertial sensors with GPS over GPS alone. PMID:24569773

Application of GPS systems on a mobile robot

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Cao, Peter; Saxena, Mayank; Tedder, Maurice; Mischalske, Steve; Hall, Ernest L.

2001-10-01

The purpose of this paper is to describe the use of Global Positioning Systems (GPS) as geographic information and navigational system for a ground based mobile robot. Several low cost wireless systems are now available for a variety of innovative automobile applications including location, messaging and tracking and security. Experiments were conducted with a test bed mobile robot, Bearcat II, for point-to-point motion using a Motorola GPS in June 2001. The Motorola M12 Oncore GPS system is connected to the Bearcat II main control computer through a RS232 interface. A mapping program is used to define a desired route. Then GPS information may be displayed for verification. However, the GPS information is also used to update the control points of the mobile robot using a reinforcement learning method. Local position updates are also used when found in the environment. The significance of the method is in extending the use of GPS to local vehicle control that requires more resolution that is available from the raw data using the adaptive control method.

GPS-based satellite tracking system for precise positioning

Science.gov (United States)

Yunck, T. P.; Melbourne, W. G.; Thornton, C. L.

1985-01-01

NASA is developing a Global Positioning System (GPS) based measurement system to provide precise determination of earth satellite orbits, geodetic baselines, ionospheric electron content, and clock offsets between worldwide tracking sites. The system will employ variations on the differential GPS observing technique and will use a network of nine fixed ground terminals. Satellite applications will require either a GPS flight receiver or an on-board GPS beacon. Operation of the system for all but satellite tracking will begin by 1988. The first major satellite application will be a demonstration of decimeter accuracy in determining the altitude of TOPEX in the early 1990's. By then the system is expected to yield long-baseline accuracies of a few centimeters and instantaneous time synchronization to 1 ns.

Evaluation on the performance of single and dual frequency low cost GPS module observation using geodetic antenna

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Dedi Atunggal

2018-06-01

Full Text Available GPS modules have been used for various applications in recent years. Its early development came in parallel with the advancement of Unmanned Aerial Vehicle (UAV technology. Nowadays, it is also used in in geographic information system (GIS data acquisition/census, mapping surveys, structure stability monitoring systems and many other applications. GPS modules generally have several positioning features, including standard positioning service (SPS, static positioning, precise point positioning (PPP, post processing kinematic (PPK and real time kinematic (RTK GPS. GPS modules in general are only equipped with a microstrip-type antenna or better known as patch antenna. Results from related research show that GPS module with this type of antenna has sub meter accuracy when used for PPK or RTK GPS method. The use of geodetic antennas is very potential to increase GPS position accuracy by up to centimeter level. This paper discusses the evaluation of GPS module measurements with geodetic type antennas for precise positioning using RTK GPS. This paper is focused on the resolution of GPS cycle ambiguity that is often expressed by the term fixing ratio and the accuracy of measurement results obtained. To provide a comprehensive description of the performance of GPS module, in this research two types of GPS module were used; single and dual frequency. Both types of GPS modules were used to conduct simultaneous observation on an open and obstructed observation location.

BDS/GPS Dual Systems Positioning Based on the Modified SR-UKF Algorithm

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JaeHyok Kong

2016-05-01

Full Text Available The Global Navigation Satellite System can provide all-day three-dimensional position and speed information. Currently, only using the single navigation system cannot satisfy the requirements of the system’s reliability and integrity. In order to improve the reliability and stability of the satellite navigation system, the positioning method by BDS and GPS navigation system is presented, the measurement model and the state model are described. Furthermore, the modified square-root Unscented Kalman Filter (SR-UKF algorithm is employed in BDS and GPS conditions, and analysis of single system/multi-system positioning has been carried out, respectively. The experimental results are compared with the traditional estimation results, which show that the proposed method can perform highly-precise positioning. Especially when the number of satellites is not adequate enough, the proposed method combine BDS and GPS systems to achieve a higher positioning precision.

GPS system simulation methodology

Science.gov (United States)

Ewing, Thomas F.

1993-01-01

The following topics are presented: background; Global Positioning System (GPS) methodology overview; the graphical user interface (GUI); current models; application to space nuclear power/propulsion; and interfacing requirements. The discussion is presented in vugraph form.

Near real-time GPS applications for tsunami early warning systems

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C. Falck

2010-02-01

Full Text Available GPS (Global Positioning System technology is widely used for positioning applications. Many of them have high requirements with respect to precision, reliability or fast product delivery, but usually not all at the same time as it is the case for early warning applications. The tasks for the GPS-based components within the GITEWS project (German Indonesian Tsunami Early Warning System, Rudloff et al., 2009 are to support the determination of sea levels (measured onshore and offshore and to detect co-seismic land mass displacements with the lowest possible latency (design goal: first reliable results after 5 min. The completed system was designed to fulfil these tasks in near real-time, rather than for scientific research requirements. The obtained data products (movements of GPS antennas are supporting the warning process in different ways. The measurements from GPS instruments on buoys allow the earliest possible detection or confirmation of tsunami waves on the ocean. Onshore GPS measurements are made collocated with tide gauges or seismological stations and give information about co-seismic land mass movements as recorded, e.g., during the great Sumatra-Andaman earthquake of 2004 (Subarya et al., 2006. This information is important to separate tsunami-caused sea height movements from apparent sea height changes at tide gauge locations (sensor station movement and also as additional information about earthquakes' mechanisms, as this is an essential information to predict a tsunami (Sobolev et al., 2007.

This article gives an end-to-end overview of the GITEWS GPS-component system, from the GPS sensors (GPS receiver with GPS antenna and auxiliary systems, either onshore or offshore to the early warning centre displays. We describe how the GPS sensors have been installed, how they are operated and the methods used to collect, transfer and process the GPS data in near real-time. This includes the sensor system design, the communication

GPS/INS Sensor Fusion Using GPS Wind up Model

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Williamson, Walton R. (Inventor)

2013-01-01

A method of stabilizing an inertial navigation system (INS), includes the steps of: receiving data from an inertial navigation system; and receiving a finite number of carrier phase observables using at least one GPS receiver from a plurality of GPS satellites; calculating a phase wind up correction; correcting at least one of the finite number of carrier phase observables using the phase wind up correction; and calculating a corrected IMU attitude or velocity or position using the corrected at least one of the finite number of carrier phase observables; and performing a step selected from the steps consisting of recording, reporting, or providing the corrected IMU attitude or velocity or position to another process that uses the corrected IMU attitude or velocity or position. A GPS stabilized inertial navigation system apparatus is also described.

The Evolution of Global Positioning System (GPS) Technology.

Science.gov (United States)

Kumar, Sameer; Moore, Kevin B.

2002-01-01

Describes technological advances in the Global Positioning System (GPS), which is also known as the NAVSTAR GPS satellite constellation program developed in 1937, and changes in the nature of our world by GPS in the areas of agriculture, health, military, transportation, environment, wildlife biology, surveying and mapping, space applications, and…

A Performance Improvement Method for Low-Cost Land Vehicle GPS/MEMS-INS Attitude Determination

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Li Cong

2015-03-01

Full Text Available Global positioning system (GPS technology is well suited for attitude determination. However, in land vehicle application, low-cost single frequency GPS receivers which have low measurement quality are often used, and external factors such as multipath and low satellite visibility in the densely built-up urban environment further degrade the quality of the GPS measurements. Due to the low-quality receivers used and the challenging urban environment, the success rate of the single epoch ambiguity resolution for dynamic attitude determination is usually quite low. In this paper, a micro-electro-mechanical system (MEMS—inertial navigation system (INS-aided ambiguity resolution method is proposed to improve the GPS attitude determination performance, which is particularly suitable for land vehicle attitude determination. First, the INS calculated baseline vector is augmented with the GPS carrier phase and code measurements. This improves the ambiguity dilution of precision (ADOP, resulting in better quality of the unconstrained float solution. Second, the undesirable float solutions caused by large measurement errors are further filtered and replaced using the INS-aided ambiguity function method (AFM. The fixed solutions are then obtained by the constrained least squares ambiguity decorrelation (CLAMBDA algorithm. Finally, the GPS/MEMS-INS integration is realized by the use of a Kalman filter. Theoretical analysis of the ADOP is given and experimental results demonstrate that our proposed method can significantly improve the quality of the float ambiguity solution, leading to high success rate and better accuracy of attitude determination.

A Performance Improvement Method for Low-Cost Land Vehicle GPS/MEMS-INS Attitude Determination

Science.gov (United States)

Cong, Li; Li, Ercui; Qin, Honglei; Ling, Keck Voon; Xue, Rui

2015-01-01

Global positioning system (GPS) technology is well suited for attitude determination. However, in land vehicle application, low-cost single frequency GPS receivers which have low measurement quality are often used, and external factors such as multipath and low satellite visibility in the densely built-up urban environment further degrade the quality of the GPS measurements. Due to the low-quality receivers used and the challenging urban environment, the success rate of the single epoch ambiguity resolution for dynamic attitude determination is usually quite low. In this paper, a micro-electro-mechanical system (MEMS)—inertial navigation system (INS)-aided ambiguity resolution method is proposed to improve the GPS attitude determination performance, which is particularly suitable for land vehicle attitude determination. First, the INS calculated baseline vector is augmented with the GPS carrier phase and code measurements. This improves the ambiguity dilution of precision (ADOP), resulting in better quality of the unconstrained float solution. Second, the undesirable float solutions caused by large measurement errors are further filtered and replaced using the INS-aided ambiguity function method (AFM). The fixed solutions are then obtained by the constrained least squares ambiguity decorrelation (CLAMBDA) algorithm. Finally, the GPS/MEMS-INS integration is realized by the use of a Kalman filter. Theoretical analysis of the ADOP is given and experimental results demonstrate that our proposed method can significantly improve the quality of the float ambiguity solution, leading to high success rate and better accuracy of attitude determination. PMID:25760057

Localization system for use in GPS denied environments

Energy Technology Data Exchange (ETDEWEB)

Trueblood, J. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-02-01

The military uses to autonomous platforms to complete missions to provide standoff for the warfighters. However autonomous platforms rely on GPS to provide their global position. In many missions spaces the autonomous platforms may encounter GPS denied environments which limits where the platform operates and requires the warfighters to takes its place. GPS denied environments can occur due to tall building, trees, canyon wall blocking the GPS satellite signals or a lack of coverage. An Inertial Navigation System (INS) uses sensors to detect the vehicle movement and direction its traveling to calculate the vehicle. One of biggest challenges with an INS system is the accuracy and accumulation of errors over time of the sensors. If these challenges can be overcome the INS would provide accurate positioning information to the autonomous vehicle in GPS denied environments and allow them to provide the desired standoff for the warfighters.

A New Indoor Positioning System Architecture Using GPS Signals.

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Xu, Rui; Chen, Wu; Xu, Ying; Ji, Shengyue

2015-04-29

The pseudolite system is a good alternative for indoor positioning systems due to its large coverage area and accurate positioning solution. However, for common Global Positioning System (GPS) receivers, the pseudolite system requires some modifications of the user terminals. To solve the problem, this paper proposes a new pseudolite-based indoor positioning system architecture. The main idea is to receive real-world GPS signals, repeat each satellite signal and transmit those using indoor transmitting antennas. The transmitted GPS-like signal can be processed (signal acquisition and tracking, navigation data decoding) by the general receiver and thus no hardware-level modification on the receiver is required. In addition, all Tx can be synchronized with each other since one single clock is used in Rx/Tx. The proposed system is simulated using a software GPS receiver. The simulation results show the indoor positioning system is able to provide high accurate horizontal positioning in both static and dynamic situations.

Derivation of some geometric parameters from GPS measurements

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Marcel Mojzeš

2005-11-01

Full Text Available Combining GPS and terrestrial data requires a common coordinate system. When the original GPS vectors do not form a network, the 3D network adjustment can not be performed. In this case, in order to integrate the GPS measurements with the terrestrial observations and to perform a combined network adjustment, the GPS measurements should be transformed to this common system. The GPS measurements which are the usual output of the GPS post processing softwares are based on the WGS84 ellipsoid and the S-JTSK local datum is based on the Bessel ellipsoid. Thus, the reduction of measurements to the S-JTSK mapping plane can not be started from the measurements resulting from GPS post processing softwares because GPS and S-JTSK don’t have the same ellipsoid. Another view of this reduction will be described in this paper.

Comparison of attitude determination approaches using multiple Global Positioning System (GPS antennas

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Wang Bing

2013-02-01

Full Text Available GPS-based attitude system is an important research field, since it is a valuable technique for the attitude determination of platforms. There exist two classes approaches for attitude determination using the GPS. The one determines attitude via baseline estimates in two frames, the other one solves for attitude by incorporating the attitude parameters directly into the GPS measurements. However, comparisons between these two classes approaches have been unexplored. First of all, two algorithms are introduced in detail which on behalf of these two kinds of approaches. Then we present numerical simulations demonstrating the performance of our algorithms and provide a comparison evaluating.

Integrated navigation of aerial robot for GPS and GPS-denied environment

International Nuclear Information System (INIS)

Suzuki, Satoshi; Min, Hongkyu; Nonami, Kenzo; Wada, Tetsuya

2016-01-01

In this study, novel robust navigation system for aerial robot in GPS and GPS- denied environments is proposed. Generally, the aerial robot uses position and velocity information from Global Positioning System (GPS) for guidance and control. However, GPS could not be used in several environments, for example, GPS has huge error near buildings and trees, indoor, and so on. In such GPS-denied environment, Laser Detection and Ranging (LIDER) sensor based navigation system have generally been used. However, LIDER sensor also has an weakness, and it could not be used in the open outdoor environment where GPS could be used. Therefore, it is desired to develop the integrated navigation system which is seamlessly applied to GPS and GPS-denied environments. In this paper, the integrated navigation system for aerial robot using GPS and LIDER is developed. The navigation system is designed based on Extended Kalman Filter, and the effectiveness of the developed system is verified by numerical simulation and experiment. (paper)

A GPS measurement system for precise satellite tracking and geodesy

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Yunck, T. P.; Wu, S.-C.; Lichten, S. M.

1985-01-01

NASA is pursuing two key applications of differential positioning with the Global Positioning System (GPS): sub-decimeter tracking of earth satellites and few-centimeter determination of ground-fixed baselines. Key requirements of the two applications include the use of dual-frequency carrier phase data, multiple ground receivers to serve as reference points, simultaneous solution for use position and GPS orbits, and calibration of atmospheric delays using water vapor radiometers. Sub-decimeter tracking will be first demonstrated on the TOPEX oceanographic satellite to be launched in 1991. A GPS flight receiver together with at least six ground receivers will acquire delta range data from the GPS carriers for non-real-time analysis. Altitude accuracies of 5 to 10 cm are expected. For baseline measurements, efforts will be made to obtain precise differential pseudorange by resolving the cycle ambiguity in differential carrier phase. This could lead to accuracies of 2 or 3 cm over a few thousand kilometers. To achieve this, a high-performance receiver is being developed, along with improved calibration and data processing techniques. Demonstrations may begin in 1986.

GPS-based tracking system for TOPEX orbit determination

Science.gov (United States)

Melbourne, W. G.

1984-01-01

A tracking system concept is discussed that is based on the utilization of the constellation of Navstar satellites in the Global Positioning System (GPS). The concept involves simultaneous and continuous metric tracking of the signals from all visible Navstar satellites by approximately six globally distributed ground terminals and by the TOPEX spacecraft at 1300-km altitude. Error studies indicate that this system could be capable of obtaining decimeter position accuracies and, most importantly, around 5 cm in the radial component which is key to exploiting the full accuracy potential of the altimetric measurements for ocean topography. Topics covered include: background of the GPS, the precision mode for utilization of the system, past JPL research for using the GPS in precision applications, the present tracking system concept for high accuracy satellite positioning, and results from a proof-of-concept demonstration.

A Low Cost GPS System for Real-Time Tracking of Sounding Rockets

Science.gov (United States)

Markgraf, M.; Montenbruck, O.; Hassenpflug, F.; Turner, P.; Bull, B.; Bauer, Frank (Technical Monitor)

2001-01-01

This paper describes the development as well as the on-ground and the in-flight evaluation of a low cost Global Positioning System (GPS) system for real-time tracking of sounding rockets. The flight unit comprises a modified ORION GPS receiver and a newly designed switchable antenna system composed of a helical antenna in the rocket tip and a dual-blade antenna combination attached to the body of the service module. Aside from the flight hardware a PC based terminal program has been developed to monitor the GPS data and graphically displays the rocket's path during the flight. In addition an Instantaneous Impact Point (IIP) prediction is performed based on the received position and velocity information. In preparation for ESA's Maxus-4 mission, a sounding rocket test flight was carried out at Esrange, Kiruna, on 19 Feb. 2001 to validate existing ground facilities and range safety installations. Due to the absence of a dedicated scientific payload, the flight offered the opportunity to test multiple GPS receivers and assess their performance for the tracking of sounding rockets. In addition to the ORION receiver, an Ashtech G12 HDMA receiver and a BAE (Canadian Marconi) Allstar receiver, both connected to a wrap-around antenna, have been flown on the same rocket as part of an independent experiment provided by the Goddard Space Flight Center. This allows an in-depth verification and trade-off of different receiver and antenna concepts.

Relative navigation and attitude determination using a GPS/INS integrated system near the International Space Station

Science.gov (United States)

Um, Jaeyong

2001-08-01

The Space Integrated GPS/INS (SIGI) sensor is the primary navigation and attitude determination source for the International Space Station (ISS). The SIGI was successfully demonstrated on-orbit for the first time in the SIGI Orbital Attitude Readiness (SOAR) demonstration on the Space Shuttle Atlantis in May 2000. Numerous proximity operations near the ISS have been and will be performed over the lifetime of the Station. The development of an autonomous relative navigation system is needed to improve the safety and efficiency of vehicle operations near the ISS. A hardware simulation study was performed for the GPS-based relative navigation using the state vector difference approach and the interferometric approach in the absence of multipath. The interferometric approach, where the relative states are estimated directly, showed comparable results for a 1 km baseline. One of the most pressing current technical issues is the design of an autonomous relative navigation system in the proximity of the ISS, where GPS signals are blocked and maneuvers happen frequently. An integrated GPS/INS system is investigated for the possibility of a fully autonomous relative navigation system. Another application of GPS measurements is determination of the vehicle's orientation in space. This study used the SOAR experiment data to characterize the SICI's on-orbit performance for attitude determination. A cold start initialization algorithm was developed for integer ambiguity resolution in any initial orientation. The original algorithm that was used in the SIGI had an operational limitation in the integer ambiguity resolution, which was developed for terrestrial applications, and limited its effectiveness in space. The new algorithm was tested using the SOAR data and has been incorporated in the current SIGI flight software. The attitude estimation performance was examined using two different GPS/INS integration algorithms. The GPS/INS attitude solution using the SOAR data was as

Assessing the role of GPs in Nordic health care systems.

Science.gov (United States)

Quaye, Randolph K

2016-05-03

Purpose This paper examines the changing role of general practitioners (GPs) in Nordic countries of Sweden, Norway and Denmark. It aims to explore the "gate keeping" role of GPs in the face of current changes in the health care delivery systems in these countries. Design/methodology/approach Data were collected from existing literature, interviews with GPs, hospital specialists and representatives of Danish regions and Norwegian Medical Association. Findings The paper contends that in all these changes, the position of the GPs in the medical division of labor has been strengthened, and patients now have increased and broadened access to choice. Research limitations/implications Health care cost and high cancer mortality rates have forced Nordic countries of Sweden, Norway and Denmark to rethink their health care systems. Several attempts have been made to reduce health care cost through market reform and by strenghtening the position of GPs. The evidence suggests that in Norway and Denmark, right incentives are in place to achieve this goal. Sweden is not far behind. The paper has limitations of a small sample size and an exclusive focus on GPs. Practical implications Anecdotal evidence suggests that physicians are becoming extremely unhappy. Understanding the changing status of primary care physicians will yield valuable information for assessing the effectiveness of Nordic health care delivery systems. Social implications This study has wider implications of how GPs see their role as potential gatekeepers in the Nordic health care systems. The role of GPs is changing as a result of recent health care reforms. Originality/value This paper contends that in Norway and Denmark, right incentives are in place to strengthen the position of GPs.

Norwegians GPs' use of electronic patient record systems.

Science.gov (United States)

Christensen, Tom; Faxvaag, Arild; Loerum, Hallvard; Grimsmo, Anders

2009-12-01

To evaluate GPs use of three major electronic patient record systems with emphasis on the ability of the systems to support important clinical tasks and to compare the findings with results from a study of the three major hospital-wide systems. A national, cross-sectional questionnaire survey was conducted in Norwegian primary care. 247 (73%) of 338 GPs responded. Proportions of the respondents who reported to use the EPR system to conduct 23 central clinical tasks, differences in the proportions of users of different EPR systems and user satisfaction and perceived usefulness of the EPR system were measured. The GPs reported extensive use of their EPR systems to support clinical tasks. There were no significant differences in functionality between the systems, but there were differences in reported software and hardware dysfunction and user satisfaction. The respondents reported high scores in computer literacy and there was no correlation between computer usage and respondent age or gender. A comparison with hospital physicians' use of three hospital-wide EPR systems revealed that GPs had higher usage than the hospital-based MDs. Primary care EPR systems support clinical tasks far better than hospital systems with better overall user satisfaction and reported impact on the overall quality of the work. EPR systems in Norwegian primary care that have been developed in accordance with the principles of user-centered design have achieved widespread adoption and highly integrated use. The quality and efficiency of the clinical work has increased in contrast to the situation of their hospital colleagues, who report more modest use and benefits of EPR systems.

Overcoming urban GPS navigation challenges through the use of MEMS inertial sensors and proper verification of navigation system performance

Science.gov (United States)

Vinande, Eric T.

This research proposes several means to overcome challenges in the urban environment to ground vehicle global positioning system (GPS) receiver navigation performance through the integration of external sensor information. The effects of narrowband radio frequency interference and signal attenuation, both common in the urban environment, are examined with respect to receiver signal tracking processes. Low-cost microelectromechanical systems (MEMS) inertial sensors, suitable for the consumer market, are the focus of receiver augmentation as they provide an independent measure of motion and are independent of vehicle systems. A method for estimating the mounting angles of an inertial sensor cluster utilizing typical urban driving maneuvers is developed and is able to provide angular measurements within two degrees of truth. The integration of GPS and MEMS inertial sensors is developed utilizing a full state navigation filter. Appropriate statistical methods are developed to evaluate the urban environment navigation improvement due to the addition of MEMS inertial sensors. A receiver evaluation metric that combines accuracy, availability, and maximum error measurements is presented and evaluated over several drive tests. Following a description of proper drive test techniques, record and playback systems are evaluated as the optimal way of testing multiple receivers and/or integrated navigation systems in the urban environment as they simplify vehicle testing requirements.

Error Analysis System for Spacecraft Navigation Using the Global Positioning System (GPS)

Science.gov (United States)

Truong, S. H.; Hart, R. C.; Hartman, K. R.; Tomcsik, T. L.; Searl, J. E.; Bernstein, A.

1997-01-01

The Flight Dynamics Division (FDD) at the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) is currently developing improved space-navigation filtering algorithms to use the Global Positioning System (GPS) for autonomous real-time onboard orbit determination. In connection with a GPS technology demonstration on the Small Satellite Technology Initiative (SSTI)/Lewis spacecraft, FDD analysts and programmers have teamed with the GSFC Guidance, Navigation, and Control Branch to develop the GPS Enhanced Orbit Determination Experiment (GEODE) system. The GEODE system consists of a Kalman filter operating as a navigation tool for estimating the position, velocity, and additional states required to accurately navigate the orbiting Lewis spacecraft by using astrodynamic modeling and GPS measurements from the receiver. A parallel effort at the FDD is the development of a GPS Error Analysis System (GEAS) that will be used to analyze and improve navigation filtering algorithms during development phases and during in-flight calibration. For GEAS, the Kalman filter theory is extended to estimate the errors in position, velocity, and other error states of interest. The estimation of errors in physical variables at regular intervals will allow the time, cause, and effect of navigation system weaknesses to be identified. In addition, by modeling a sufficient set of navigation system errors, a system failure that causes an observed error anomaly can be traced and accounted for. The GEAS software is formulated using Object Oriented Design (OOD) techniques implemented in the C++ programming language on a Sun SPARC workstation. The Phase 1 of this effort is the development of a basic system to be used to evaluate navigation algorithms implemented in the GEODE system. This paper presents the GEAS mathematical methodology, systems and operations concepts, and software design and implementation. Results from the use of the basic system to evaluate

Rail inspection system based on iGPS

Science.gov (United States)

Fu, Xiaoyan; Wang, Mulan; Wen, Xiuping

2018-05-01

Track parameters include gauge, super elevation, cross level and so on, which could be calculated through the three-dimensional coordinates of the track. The rail inspection system based on iGPS (indoor/infrared GPS) was composed of base station, receiver, rail inspection frame, wireless communication unit, display and control unit and data processing unit. With the continuous movement of the inspection frame, the system could accurately inspect the coordinates of rail; realize the intelligent detection and precision measurement. According to principle of angle intersection measurement, the inspection model was structured, and detection process was given.

Retained satellite information influences performance of GPS devices in a forested ecosystem

Science.gov (United States)

Katie M. Moriarty; Clinton W. Epps

2015-01-01

Global Positioning System (GPS) units used in animal telemetry often suffer from nonrandom data loss and location error. GPS units use stored satellite information to estimate locations, including almanac and ephemeris data reflecting satellite positions at weekly and at <4-hr temporal scales, respectively. Using the smallest GPS collars (45–51 g) available for...

Environmental radiation monitoring system with GPS (global positioning system)

International Nuclear Information System (INIS)

Komoto, Itsuro

2000-01-01

This system combines a radiation monitoring car with GPS and a data processor (personal computer). It distributes the position information acquired through GPS to the data such as measured environmental radiation dose rate and energy spectrum. It also displays and edits the data for each measuring position on a map. Transmitting the data to the power station through mobile phone enables plan managers to easily monitor the environmental radiation dose rate nearby and proper emergency monitoring. (author)

Real-Time Vehicle Data Logging System Using GPS And GSM

OpenAIRE

Win Minn Thet; MyoMaung Maung; Hla Myo Tun

2015-01-01

Abstract This paper proposes and implements a low cost Vehicle Data Logging System using GPS and GSM. This system allows a user to trace the present and past positions recorded in SD card. This system also reads the current position of the vehicle using GPS the data is sent via GSM service from the GSM network. The vehicles position including the driving speed the UTC time and data are stored in the SD card for live and past tracking. All of that GPS data is sent to PIC 18F4520 by the Uni...

Scintillation-Hardened GPS Receiver

Science.gov (United States)

Stephens, Donald R.

2015-01-01

CommLargo, Inc., has developed a scintillation-hardened Global Positioning System (GPS) receiver that improves reliability for low-orbit missions and complies with NASA's Space Telecommunications Radio System (STRS) architecture standards. A software-defined radio (SDR) implementation allows a single hardware element to function as either a conventional radio or as a GPS receiver, providing backup and redundancy for platforms such as the International Space Station (ISS) and high-value remote sensing platforms. The innovation's flexible SDR implementation reduces cost, weight, and power requirements. Scintillation hardening improves mission reliability and variability. In Phase I, CommLargo refactored an open-source GPS software package with Kalman filter-based tracking loops to improve performance during scintillation and also demonstrated improved navigation during a geomagnetic storm. In Phase II, the company generated a new field-programmable gate array (FPGA)-based GPS waveform to demonstrate on NASA's Space Communication and Navigation (SCaN) test bed.

Autonomous Navigation of the SSTI/Lewis Spacecraft Using the Global Positioning System (GPS)

Science.gov (United States)

Hart, R. C.; Long, A. C.; Lee, T.

1997-01-01

The National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) Flight Dynamics Division (FDD) is pursuing the application of Global Positioning System (GPS) technology to improve the accuracy and economy of spacecraft navigation. High-accuracy autonomous navigation algorithms are being flight qualified in conjunction with GSFC's GPS Attitude Determination Flyer (GADFLY) experiment on the Small Satellite Technology Initiative (SSTI) Lewis spacecraft, which is scheduled for launch in 1997. Preflight performance assessments indicate that these algorithms can provide a real-time total position accuracy of better than 10 meters (1 sigma) and velocity accuracy of better than 0.01 meter per second (1 sigma), with selective availability at typical levels. This accuracy is projected to improve to the 2-meter level if corrections to be provided by the GPS Wide Area Augmentation System (WAAS) are included.

Development of GPS data remote retrieval system using wireless LAN

Directory of Open Access Journals (Sweden)

Koichiro Doi

2012-11-01

Full Text Available A remote retrieval system, using a wireless LAN, was developed to retrieve dual-frequency GPS data. The system consists of a ground observation unit (comprising a dual-frequency GPS logger and a data transmission unit and a data retrieval unit. In this system, we use the ZigBee communication protocol to transmit control commands (2.4 GHz, 250 Kbps and a wireless LAN communication to transmit GPS data (2.4 GHz, 54 Mbps. Data of every 30 seconds to transmit to the data retrieval unit are re-sampled from 1-second data at 00 UT each day. We conducted three data-transmission tests with the system: (1 a ground data retrieval test, (2 a data retrieval test from the atmosphere of a few hundred meters high using a small unmanned aircraft, and (3 actual GPS-data retrieval tests from a GPS buoy deployed on sea ice at Nisi-no-ura Cove, Syowa Station, Antarctica. In test (1, we successfully received all the data from the ground observation unit when situated at distances of less than 400 m from the data retrieval unit. In test (2, we obtained approximately 24.5 MB of data from the aircraft at heights of less than 250 m. In test (3, we obtained approximately 23.5 MB of data from the GPS buoy within 10 minutes. The proposed system has the advantage of enabling continuous measurements without aborting the measurement at the data retrievals.

The future of GPS-based electric power system measurements, operation and control

Energy Technology Data Exchange (ETDEWEB)

Rizy, D.T. [Oak Ridge National Lab., TN (United States); Wilson, R.E. [Western Area Power Administration, Golden, CO (United States); Martin, K.E.; Litzenberger, W.H. [Bonneville Power Administration, Portland, OR (United States); Hauer, J.F. [Pacific Northwest National Lab., Richland, WA (United States); Overholt, P.N. [Dept. of Energy, Washington, DC (United States); Sobajic, D.J. [Electric Power Research Inst., Palo Alto, CA (United States)

1998-11-01

Much of modern society is powered by inexpensive and reliable electricity delivered by a complex and elaborate electric power network. Electrical utilities are currently using the Global Positioning System-NAVSTAR (GPS) timekeeping to improve the network`s reliability. Currently, GPS synchronizes the clocks on dynamic recorders and aids in post-mortem analysis of network disturbances. Two major projects have demonstrated the use of GPS-synchronized power system measurements. In 1992, the Electric Power Research Institute`s (EPRI) sponsored Phase Measurements Project used a commercially available Phasor Measurements Unit (PMU) to collect GPS-synchronized measurements for analyzing power system problems. In 1995, Bonneville Power Administration (BPA) and Western Area Power Administration (WAPA) under DOE`s and EPRI`s sponsorship launched the Wide Area Measurements (WAMS) project. WAMS demonstrated GPS-synchronized measurements over a large area of their power networks and demonstrated the networking of GPS-based measurement systems in BPA and WAPA. The phasor measurement technology has also been used to conduct dynamic power system tests. During these tests, a large dynamic resistor was inserted to simulate a small power system disturbance.

Modular Software for Spacecraft Navigation Using the Global Positioning System (GPS)

Science.gov (United States)

Truong, S. H.; Hartman, K. R.; Weidow, D. A.; Berry, D. L.; Oza, D. H.; Long, A. C.; Joyce, E.; Steger, W. L.

1996-01-01

The Goddard Space Flight Center Flight Dynamics and Mission Operations Divisions have jointly investigated the feasibility of engineering modular Global Positioning SYSTEM (GPS) navigation software to support both real time flight and ground postprocessing configurations. The goals of this effort are to define standard GPS data interfaces and to engineer standard, reusable navigation software components that can be used to build a broad range of GPS navigation support applications. The paper discusses the GPS modular software (GMOD) system and operations concepts, major requirements, candidate software architecture, feasibility assessment and recommended software interface standards. In additon, ongoing efforts to broaden the scope of the initial study and to develop modular software to support autonomous navigation using GPS are addressed,

Combined GPS/GLONASS Precise Point Positioning with Fixed GPS Ambiguities

Science.gov (United States)

Pan, Lin; Cai, Changsheng; Santerre, Rock; Zhu, Jianjun

2014-01-01

Precise point positioning (PPP) technology is mostly implemented with an ambiguity-float solution. Its performance may be further improved by performing ambiguity-fixed resolution. Currently, the PPP integer ambiguity resolutions (IARs) are mainly based on GPS-only measurements. The integration of GPS and GLONASS can speed up the convergence and increase the accuracy of float ambiguity estimates, which contributes to enhancing the success rate and reliability of fixing ambiguities. This paper presents an approach of combined GPS/GLONASS PPP with fixed GPS ambiguities (GGPPP-FGA) in which GPS ambiguities are fixed into integers, while all GLONASS ambiguities are kept as float values. An improved minimum constellation method (MCM) is proposed to enhance the efficiency of GPS ambiguity fixing. Datasets from 20 globally distributed stations on two consecutive days are employed to investigate the performance of the GGPPP-FGA, including the positioning accuracy, convergence time and the time to first fix (TTFF). All datasets are processed for a time span of three hours in three scenarios, i.e., the GPS ambiguity-float solution, the GPS ambiguity-fixed resolution and the GGPPP-FGA resolution. The results indicate that the performance of the GPS ambiguity-fixed resolutions is significantly better than that of the GPS ambiguity-float solutions. In addition, the GGPPP-FGA improves the positioning accuracy by 38%, 25% and 44% and reduces the convergence time by 36%, 36% and 29% in the east, north and up coordinate components over the GPS-only ambiguity-fixed resolutions, respectively. Moreover, the TTFF is reduced by 27% after adding GLONASS observations. Wilcoxon rank sum tests and chi-square two-sample tests are made to examine the significance of the improvement on the positioning accuracy, convergence time and TTFF. PMID:25237901

Combined GPS/GLONASS Precise Point Positioning with Fixed GPS Ambiguities

Directory of Open Access Journals (Sweden)

Lin Pan

2014-09-01

Full Text Available Precise point positioning (PPP technology is mostly implemented with an ambiguity-float solution. Its performance may be further improved by performing ambiguity-fixed resolution. Currently, the PPP integer ambiguity resolutions (IARs are mainly based on GPS-only measurements. The integration of GPS and GLONASS can speed up the convergence and increase the accuracy of float ambiguity estimates, which contributes to enhancing the success rate and reliability of fixing ambiguities. This paper presents an approach of combined GPS/GLONASS PPP with fixed GPS ambiguities (GGPPP-FGA in which GPS ambiguities are fixed into integers, while all GLONASS ambiguities are kept as float values. An improved minimum constellation method (MCM is proposed to enhance the efficiency of GPS ambiguity fixing. Datasets from 20 globally distributed stations on two consecutive days are employed to investigate the performance of the GGPPP-FGA, including the positioning accuracy, convergence time and the time to first fix (TTFF. All datasets are processed for a time span of three hours in three scenarios, i.e., the GPS ambiguity-float solution, the GPS ambiguity-fixed resolution and the GGPPP-FGA resolution. The results indicate that the performance of the GPS ambiguity-fixed resolutions is significantly better than that of the GPS ambiguity-float solutions. In addition, the GGPPP-FGA improves the positioning accuracy by 38%, 25% and 44% and reduces the convergence time by 36%, 36% and 29% in the east, north and up coordinate components over the GPS-only ambiguity-fixed resolutions, respectively. Moreover, the TTFF is reduced by 27% after adding GLONASS observations. Wilcoxon rank sum tests and chi-square two-sample tests are made to examine the significance of the improvement on the positioning accuracy, convergence time and TTFF.

Connected motorcycle system performance.

Science.gov (United States)

2016-01-15

This project characterized the performance of Connected Vehicle Systems (CVS) on motorcycles based on two key components: global positioning and wireless communication systems. Considering that Global Positioning System (GPS) and 5.9 GHz Dedicated Sh...

Kinematic-PPP using Single/Dual Frequency Observations from (GPS, GLONASS and GPS/GLONASS) Constellations for Hydrography

Science.gov (United States)

Farah, Ashraf

2018-03-01

Global Positioning System (GPS) technology is ideally suited for inshore and offshore positioning because of its high accuracy and the short observation time required for a position fix. Precise point positioning (PPP) is a technique used for position computation with a high accuracy using a single GNSS receiver. It relies on highly accurate satellite position and clock data that can be acquired from different sources such as the International GNSS Service (IGS). PPP precision varies based on positioning technique (static or kinematic), observations type (single or dual frequency) and the duration of observations among other factors. PPP offers comparable accuracy to differential GPS with safe in cost and time. For many years, PPP users depended on GPS (American system) which considered the solely reliable system. GLONASS's contribution in PPP techniques was limited due to fail in maintaining full constellation. Yet, GLONASS limited observations could be integrated into GPS-based PPP to improve availability and precision. As GLONASS reached its full constellation early 2013, there is a wide interest in PPP systems based on GLONASS only and independent of GPS. This paper investigates the performance of kinematic PPP solution for the hydrographic applications in the Nile river (Aswan, Egypt) based on GPS, GLONASS and GPS/GLONASS constellations. The study investigates also the effect of using two different observation types; single-frequency and dual frequency observations from the tested constellations.

Cryospheric monitoring with new low power RTK dGPS systems

Science.gov (United States)

Martinez, K.; Hart, J. K.; Bragg, G. M.; Curry, J. S.

2017-12-01

Differential GPS is often used to measure the movement of glaciers. It requires data to be recorded at a fixed base station as well as the moving rover unit, followed by post-processing in order to compute the rover's positions. The typical dGPS units used consume considerable power and the recording times are often around one hour per reading. While this provides very precise (typically millimetre) precision it comes at a cost of power used and the data is rather large to send offsite regularly. Real-time kinematic modes of dGPS are typically used for rapid mapping and autonomous vehicles. New devices are lower cost and smaller size. They also provide a fix within a few minutes, which can be transmitted home. We describe the design, deployment and preliminary results of two tracking systems to monitor ice movement. The first used a normal GPS and Iridium satellite messaging to track the movement of a Greenland iceberg which calved from the Nattivit Apusiiat glacier (south west Greenland). This system followed the iceberg as it flowed 660 km south along the coast of Greenland. The second system was installed in Iceland to track the movement of glaciers using 2 different dGPS systems. A low power ARM Cortex M4-based controller ran Python code to schedule dGPS activity periodically and gather fixes. An Iridium short messaging unit (Rockblock) was used to transmit RTK location fixes. The aim was to experiment with the use of RTK dGPS as an alternative to recordings to measure how the glaciers responded to small scale changes in temperature and precipitation throughout the year.

Communication plan of GPS monitoring system based on the Internet

Science.gov (United States)

Xing, Xiangpeng; Liu, Zhenan; Bao, Yuanlu

2005-11-01

In GPS monitoring system, wireless communications network is necessary to keep base station in contact with mobile stations. Public communications network and personal communications network can't work well all the time. In this article, an economical communications network that can be competent for communication of GPS monitoring system is introduced. Personal communications network is used in this GPS monitoring system. In order to enlarge the coverage area and to expand the capacity of the personal communications network, the concept of cellular radio system is introduced. Because only the non-adjacent cells can use the same frequency channel, handoff of mobile station is extremely important when it goes in another cell. The mobile station of the system will know its own longitude and latitude by receiving data from GPS satellites all the time, so it can change its working frequency channel according to its position. Internet, instead of personal communication cable, is used to connect the base stations. So the communications network has the advantage of public communications network and personal one.

76 FR 67019 - Eighty-Seventh: RTCA Special Committee 159: Global Positioning System (GPS)

Science.gov (United States)

2011-10-28

... Committee 159: Global Positioning System (GPS) AGENCY: Federal Aviation Administration (FAA), U.S... System (GPS). SUMMARY: The FAA is issuing this notice to advise the public of a meeting of RTCA Special Committee 159: Global Positioning System (GPS) 87th meeting. DATES: The meeting will be held November 14-18...

Hacking GPS

CERN Document Server

Kingsley-Hughes, Kathie

2005-01-01

* This is the "user manual" that didn't come with any of the 30 million GPS receivers currently in use, showing readers how to modify, tweak, and hack their GPS to take it to new levels!* Crazy-cool modifications include exploiting secret keycodes, revealing hidden features, building power cords and cables, hacking the battery and antenna, protecting a GPS from impact and falls, making a screen protector, and solar-powering a GPS* Potential power users will take the function and performance of their GPS to a whole new level by hacking into the firmware and hacking into a PC connection with a GPS* Fear not! Any potentially dangerous mod (to the device) is clearly labeled, with precautions listed that should be taken* Game time! Readers can check out GPS games, check into hacking geocaching, and even use a GPS as a metal detector

FPGA-based real-time embedded system for RISS/GPS integrated navigation.

Science.gov (United States)

Abdelfatah, Walid Farid; Georgy, Jacques; Iqbal, Umar; Noureldin, Aboelmagd

2012-01-01

Navigation algorithms integrating measurements from multi-sensor systems overcome the problems that arise from using GPS navigation systems in standalone mode. Algorithms which integrate the data from 2D low-cost reduced inertial sensor system (RISS), consisting of a gyroscope and an odometer or wheel encoders, along with a GPS receiver via a Kalman filter has proved to be worthy in providing a consistent and more reliable navigation solution compared to standalone GPS receivers. It has been also shown to be beneficial, especially in GPS-denied environments such as urban canyons and tunnels. The main objective of this paper is to narrow the idea-to-implementation gap that follows the algorithm development by realizing a low-cost real-time embedded navigation system capable of computing the data-fused positioning solution. The role of the developed system is to synchronize the measurements from the three sensors, relative to the pulse per second signal generated from the GPS, after which the navigation algorithm is applied to the synchronized measurements to compute the navigation solution in real-time. Employing a customizable soft-core processor on an FPGA in the kernel of the navigation system, provided the flexibility for communicating with the various sensors and the computation capability required by the Kalman filter integration algorithm.

Railway testing using a portable ride quality and vibration measurement system with GPS

Science.gov (United States)

Mee, Brian; Whitten, Brian; Neijikovsky, Boris

1995-06-01

To conduct the testing and evaluation of railway and railway vehicles, the Federal Railroad Administration developed a protable system that consists of accelerometers oriented in the vertical and horizontal directions, a Global Positioning System (GPS) receiver, data collection and power systems, and a portable computer. Commercial software was used to collect and display the data, while software, developed by ENSCO, was used to analyze and display results. The GPS provided dynamic location to an accuracy of 30 meters or better, and vehicle speed to within one mile per hour. The system was used in the demonstration tests of several advanced high-speed trains on Amtrak's Northeast Corrider and on other tracks in the US. The portable measurement system proved to be a simple and effective device to characterize the vibration environment of any transportation system. It is ideal for use in the assessment of the safe performance of high-speed trains operating at high cant deficiency. The system has also been used for other field tests, including braking performance and bridge monitoring. This report discusses the portable measurement system, the test applications that the system has been used for, the results of thoses tests, and the potential for improvements.

GPS-Based Highway Performance Monitoring Performance Monitoring Using GPS: Characterization of Travel Speeds on any Roadway Segment

OpenAIRE

Kornhauser, Alain L.

2012-01-01

Presented is a characterization of travel speed on any roadway segment based on probe vehicle position data. Most of the characterization is based position data obtained from GPS receivers because of their high precision and their increasing availability. Comparison is also made to Qualcomm’s Automatic Satellite Position Reporting (QASPR) system because of its long history (10+ years) of extensive use by the long-haul trucking industry. Described is the use of these data in conjunction with d...

GPS water level measurements for Indonesia's Tsunami Early Warning System

Directory of Open Access Journals (Sweden)

T. Schöne

2011-03-01

Full Text Available On Boxing Day 2004, a severe tsunami was generated by a strong earthquake in Northern Sumatra causing a large number of casualties. At this time, neither an offshore buoy network was in place to measure tsunami waves, nor a system to disseminate tsunami warnings to local governmental entities. Since then, buoys have been developed by Indonesia and Germany, complemented by NOAA's Deep-ocean Assessment and Reporting of Tsunamis (DART buoys, and have been moored offshore Sumatra and Java. The suite of sensors for offshore tsunami detection in Indonesia has been advanced by adding GPS technology for water level measurements.

The usage of GPS buoys in tsunami warning systems is a relatively new approach. The concept of the German Indonesian Tsunami Early Warning System (GITEWS (Rudloff et al., 2009 combines GPS technology and ocean bottom pressure (OBP measurements. Especially for near-field installations where the seismic noise may deteriorate the OBP data, GPS-derived sea level heights provide additional information.

The GPS buoy technology is precise enough to detect medium to large tsunamis of amplitudes larger than 10 cm. The analysis presented here suggests that for about 68% of the time, tsunamis larger than 5 cm may be detectable.

VEHICLE TRACKING AND MONITORING SYSTEM USING GPS AND GSM/GPRS.

OpenAIRE

*Arsheen Barnagarwala, *Aziz Buriwala

2017-01-01

Abstract: This system offers an affordable and compact design implemented for tracking and monitoring vehicle’s Instantaneous speed, peak speed, distance and current location with the help of Global Positioning System (GPS) and Global System for Mobile Communication (GSM). The system consist of two parts, one is ambulatory and incorporated in the target vehicle which comprises of a GPS receiver, a microcontroller and a GSM modem with periphery display and power units. Other is stable at a rem...

Anti-Jam GPS Antennas for Wearable Dismounted Soldier Navigation Systems

Science.gov (United States)

2016-06-01

GPS antenna, the Novatel GAJT-700M/ L CRPA is currently being considered, as shown in Fig. 6. Fig. 6 A basic 7-element CRPA (right) compared with a...ARL-TR-7670 ● JUNE 2016 US Army Research Laboratory Anti-Jam GPS Antennas for Wearable Dismounted Soldier Navigation Systems...longer needed. Do not return it to the originator. ARL-TR-7670 ● JUNE 2016 US Army Research Laboratory Anti-Jam GPS Antennas for

Study of Robust H∞ Filtering Application in Loosely Coupled INS/GPS System

Directory of Open Access Journals (Sweden)

Lin Zhao

2014-01-01

model, unstable model case is considered. We give an explanation for Kalman filter divergence under uncertain dynamic system and simultaneously investigate the relationship between H∞ filter and Kalman filter. A loosely coupled INS/GPS simulation system is given here to verify this application. Result shows that the robust H∞ filter has a better performance when system suffers uncertainty; also it is more robust compared to the conventional Kalman filter.

78 FR 13396 - 90th Meeting: RTCA Special Committee 159, Global Positioning Systems (GPS)

Science.gov (United States)

2013-02-27

... 159, Global Positioning Systems (GPS) AGENCY: Federal Aviation Administration (FAA), U.S. Department... 159, Global Positioning Systems (GPS) SUMMARY: The FAA is issuing this notice to advise the public of the eighty-ninth meeting of the RTCA Special Committee 159, Global Positioning Systems (GPS). DATES...

78 FR 57672 - 91st Meeting: RTCA Special Committee 159, Global Positioning Systems (GPS)

Science.gov (United States)

2013-09-19

... 159, Global Positioning Systems (GPS) AGENCY: Federal Aviation Administration (FAA), U.S. Department... 159, Global Positioning Systems (GPS). SUMMARY: The FAA is issuing this notice to advise the public of the ninety-first meeting of the RTCA Special Committee 159, Global Positioning Systems (GPS) DATES...

Robust GPS autonomous signal quality monitoring

Science.gov (United States)

Ndili, Awele Nnaemeka

The Global Positioning System (GPS), introduced by the U.S. Department of Defense in 1973, provides unprecedented world-wide navigation capabilities through a constellation of 24 satellites in global orbit, each emitting a low-power radio-frequency signal for ranging. GPS receivers track these transmitted signals, computing position to within 30 meters from range measurements made to four satellites. GPS has a wide range of applications, including aircraft, marine and land vehicle navigation. Each application places demands on GPS for various levels of accuracy, integrity, system availability and continuity of service. Radio frequency interference (RFI), which results from natural sources such as TV/FM harmonics, radar or Mobile Satellite Systems (MSS), presents a challenge in the use of GPS, by posing a threat to the accuracy, integrity and availability of the GPS navigation solution. In order to use GPS for integrity-sensitive applications, it is therefore necessary to monitor the quality of the received signal, with the objective of promptly detecting the presence of RFI, and thus provide a timely warning of degradation of system accuracy. This presents a challenge, since the myriad kinds of RFI affect the GPS receiver in different ways. What is required then, is a robust method of detecting GPS accuracy degradation, which is effective regardless of the origin of the threat. This dissertation presents a new method of robust signal quality monitoring for GPS. Algorithms for receiver autonomous interference detection and integrity monitoring are demonstrated. Candidate test statistics are derived from fundamental receiver measurements of in-phase and quadrature correlation outputs, and the gain of the Active Gain Controller (AGC). Performance of selected test statistics are evaluated in the presence of RFI: broadband interference, pulsed and non-pulsed interference, coherent CW at different frequencies; and non-RFI: GPS signal fading due to physical blockage and

A GPS-based Real-time Road Traffic Monitoring System

Science.gov (United States)

Tanti, Kamal Kumar

In recent years, monitoring systems are astonishingly inclined towards ever more automatic; reliably interconnected, distributed and autonomous operation. Specifically, the measurement, logging, data processing and interpretation activities may be carried out by separate units at different locations in near real-time. The recent evolution of mobile communication devices and communication technologies has fostered a growing interest in the GIS & GPS-based location-aware systems and services. This paper describes a real-time road traffic monitoring system based on integrated mobile field devices (GPS/GSM/IOs) working in tandem with advanced GIS-based application software providing on-the-fly authentications for real-time monitoring and security enhancement. The described system is developed as a fully automated, continuous, real-time monitoring system that employs GPS sensors and Ethernet and/or serial port communication techniques are used to transfer data between GPS receivers at target points and a central processing computer. The data can be processed locally or remotely based on the requirements of client’s satisfaction. Due to the modular architecture of the system, other sensor types may be supported with minimal effort. Data on the distributed network & measurements are transmitted via cellular SIM cards to a Control Unit, which provides for post-processing and network management. The Control Unit may be remotely accessed via an Internet connection. The new system will not only provide more consistent data about the road traffic conditions but also will provide methods for integrating with other Intelligent Transportation Systems (ITS). For communication between the mobile device and central monitoring service GSM technology is used. The resulting system is characterized by autonomy, reliability and a high degree of automation.

The Integration of GPS Navigator Device with Vehicles Tracking System for Rental Cars Firms

OpenAIRE

Omarah O. Alharaki; Fahad S. Alaieri; Akram M. Zeki

2010-01-01

The aim of this research is to integrate the GPS tracking system (tracking device and web-based application) with GPS navigator for rental cars, allowing the company to use various applications to monitor and manage the cars. This is enable the firms and customers to communicate with each other via the GPS navigator. The system should be developed by applying new features in GPS tracking application devices in vehicles. This paper also proposes new features that can be applied to the GPS Navi...

INS/GPS/LiDAR Integrated Navigation System for Urban and Indoor Environments Using Hybrid Scan Matching Algorithm.

Science.gov (United States)

Gao, Yanbin; Liu, Shifei; Atia, Mohamed M; Noureldin, Aboelmagd

2015-09-15

This paper takes advantage of the complementary characteristics of Global Positioning System (GPS) and Light Detection and Ranging (LiDAR) to provide periodic corrections to Inertial Navigation System (INS) alternatively in different environmental conditions. In open sky, where GPS signals are available and LiDAR measurements are sparse, GPS is integrated with INS. Meanwhile, in confined outdoor environments and indoors, where GPS is unreliable or unavailable and LiDAR measurements are rich, LiDAR replaces GPS to integrate with INS. This paper also proposes an innovative hybrid scan matching algorithm that combines the feature-based scan matching method and Iterative Closest Point (ICP) based scan matching method. The algorithm can work and transit between two modes depending on the number of matched line features over two scans, thus achieving efficiency and robustness concurrently. Two integration schemes of INS and LiDAR with hybrid scan matching algorithm are implemented and compared. Real experiments are performed on an Unmanned Ground Vehicle (UGV) for both outdoor and indoor environments. Experimental results show that the multi-sensor integrated system can remain sub-meter navigation accuracy during the whole trajectory.

75 FR 2581 - Eighty-First Meeting: RTCA Special Committee 159: Global Positioning System (GPS)

Science.gov (United States)

2010-01-15

... Committee 159: Global Positioning System (GPS) AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 159 meeting: Global Positioning System (GPS). SUMMARY: The FAA is... System (GPS). DATES: The meeting will be held February 2-5, 2010, from 9 a.m. to 4:30 p.m. (unless stated...

76 FR 27744 - Eighty-Fifth Meeting: RTCA Special Committee 159: Global Positioning System (GPS)

Science.gov (United States)

2011-05-12

... Committee 159: Global Positioning System (GPS) AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 159 meeting: Global Positioning System (GPS). SUMMARY: The FAA is... System (GPS). DATES: The meeting will be held May 26, 2011, from 9 a.m. to 11:45 a.m. ADDRESSES: The...

76 FR 33022 - Eighty-Sixth Meeting: RTCA Special Committee 159: Global Positioning System (GPS)

Science.gov (United States)

2011-06-07

... Committee 159: Global Positioning System (GPS) AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 159 meeting: Global Positioning System (GPS). SUMMARY: The FAA is... System (GPS). DATES: The meeting will be held June 13-17, 2011, from 9 a.m. to 4:30 p.m. ADDRESSES: The...

77 FR 12106 - 88th Meeting: RTCA Special Committee 159, Global Positioning System (GPS)

Science.gov (United States)

2012-02-28

... 159, Global Positioning System (GPS) AGENCY: Federal Aviation Administration (FAA), U.S. Department of Transportation (DOT). ACTION: Notice of RTCA Special Committee 159, Global Positioning System (GPS). SUMMARY: The..., Global Positioning System (GPS). DATES: The meeting will be held March 13-16, 2012, from 9 a.m.-4:30 p.m...

A Pedestrian Dead Reckoning System Integrating Low-Cost MEMS Inertial Sensors and GPS Receiver

Directory of Open Access Journals (Sweden)

Jin-feng Li

2014-04-01

Full Text Available The body-mounted inertial systems for pedestrian navigation do not require any preinstalled facilities and can run autonomously. The advantages over other technologies make it especially attractive for the applications such as first responders, military and consumer markets. The hardware platform integrating the low-cost, low-power and small-size MEMS (micro-electro-mechanical systems inertial sensors and GPS (global positioning system receiver is proposed. When the satellite signals are available, the location of the pedestrian is directly obtained from the GPS receiver. The inertial sensors are the complement of the GPS receiver in places where the GPS signals are not available, such as indoors, urban canyons and places under dense foliages. The height tracking is achieved by the barometer. The proposed PDR (pedestrian dead reckoning algorithm is real-timely implemented in the platform. The simple but effective step detection and step length estimation method are realized to reduce the computation and memory requirements on the microprocessor. A complementary filter is proposed to fuse the data from the accelerometer, gyroscope and digital compass for decreasing the heading error, which is the main error source in positioning. The reliability and accuracy of the proposed system is verified by field pedestrian walking tests in outdoors and indoors. The positioning error is less than 4% of the total traveled distance. The results indicate that the pedestrian dead reckoning system is able to provide satisfactory tracking performance.

Development of a High Precision Displacement Measurement System by Fusing a Low Cost RTK-GPS Sensor and a Force Feedback Accelerometer for Infrastructure Monitoring.

Science.gov (United States)

Koo, Gunhee; Kim, Kiyoung; Chung, Jun Yeon; Choi, Jaemook; Kwon, Nam-Yeol; Kang, Doo-Young; Sohn, Hoon

2017-11-28

A displacement measurement system fusing a low cost real-time kinematic global positioning system (RTK-GPS) receiver and a force feedback accelerometer is proposed for infrastructure monitoring. The proposed system is composed of a sensor module, a base module and a computation module. The sensor module consists of a RTK-GPS rover and a force feedback accelerometer, and is installed on a target structure like conventional RTK-GPS sensors. The base module is placed on a rigid ground away from the target structure similar to conventional RTK-GPS bases, and transmits observation messages to the sensor module. Then, the initial acceleration, velocity and displacement responses measured by the sensor module are transmitted to the computation module located at a central monitoring facility. Finally, high precision and high sampling rate displacement, velocity, and acceleration are estimated by fusing the acceleration from the accelerometer, the velocity from the GPS rover, and the displacement from RTK-GPS. Note that the proposed displacement measurement system can measure 3-axis acceleration, velocity as well as displacement in real time. In terms of displacement, the proposed measurement system can estimate dynamic and pseudo-static displacement with a root-mean-square error of 2 mm and a sampling rate of up to 100 Hz. The performance of the proposed system is validated under sinusoidal, random and steady-state vibrations. Field tests were performed on the Yeongjong Grand Bridge and Yi Sun-sin Bridge in Korea, and the Xihoumen Bridge in China to compare the performance of the proposed system with a commercial RTK-GPS sensor and other data fusion techniques.

Indoor Positioning Using GPS Revisited

DEFF Research Database (Denmark)

Kjærgaard, Mikkel Baun; Blunck, Henrik; Godsk, Torben

2010-01-01

It has been considered a fact that GPS performs too poorly inside buildings to provide usable indoor positioning. We analyze results of a measurement campaign to improve on the understanding of indoor GPS reception characteristics. The results show that using state-of-the-art receivers GPS...... low signal-to-noise ratios, multipath phenomena or bad satellite constellation geometry. We have also measured the indoor performance of embedded GPS receivers in mobile phones which provided lower availability and accuracy than state-of-the-art ones. Finally, we consider how the GPS performance...

Automated time activity classification based on global positioning system (GPS) tracking data.

Science.gov (United States)

Wu, Jun; Jiang, Chengsheng; Houston, Douglas; Baker, Dean; Delfino, Ralph

2011-11-14

Air pollution epidemiological studies are increasingly using global positioning system (GPS) to collect time-location data because they offer continuous tracking, high temporal resolution, and minimum reporting burden for participants. However, substantial uncertainties in the processing and classifying of raw GPS data create challenges for reliably characterizing time activity patterns. We developed and evaluated models to classify people's major time activity patterns from continuous GPS tracking data. We developed and evaluated two automated models to classify major time activity patterns (i.e., indoor, outdoor static, outdoor walking, and in-vehicle travel) based on GPS time activity data collected under free living conditions for 47 participants (N = 131 person-days) from the Harbor Communities Time Location Study (HCTLS) in 2008 and supplemental GPS data collected from three UC-Irvine research staff (N = 21 person-days) in 2010. Time activity patterns used for model development were manually classified by research staff using information from participant GPS recordings, activity logs, and follow-up interviews. We evaluated two models: (a) a rule-based model that developed user-defined rules based on time, speed, and spatial location, and (b) a random forest decision tree model. Indoor, outdoor static, outdoor walking and in-vehicle travel activities accounted for 82.7%, 6.1%, 3.2% and 7.2% of manually-classified time activities in the HCTLS dataset, respectively. The rule-based model classified indoor and in-vehicle travel periods reasonably well (Indoor: sensitivity > 91%, specificity > 80%, and precision > 96%; in-vehicle travel: sensitivity > 71%, specificity > 99%, and precision > 88%), but the performance was moderate for outdoor static and outdoor walking predictions. No striking differences in performance were observed between the rule-based and the random forest models. The random forest model was fast and easy to execute, but was likely less robust

Pre- and post-flight radiation performance evaluation of the space GPS receiver (SGR)

International Nuclear Information System (INIS)

Oldfield, M.K.; Underwood, C.I.; Unwin, M.J.; Asenek, V.; Harboe-Sorensen, R.

1999-01-01

SSTL (Survey Satellite Technology Ltd), in collaboration with ESA/ESTEC, recently developed a state-of-the-art low cost GPS (Global Positioning System) receiver payload for use on small satellites. The space GPS Receiver (SGR), will be flown on the TiungSAT-1 micro-satellite, UoSAT-12 mini-satellite and ESA's PROBA satellite. The SGR payload is currently flying on the TMSAT micro-satellite in low Earth orbit (LEO) and has carried out autonomous on-board positioning whilst also providing an experimental test-bed for evaluating spacecraft attitude determination algorithms. In order to reduce development time and costs, the SGR consists solely of industry standard COTS (commercial off-the-shelf) devices. This paper describes the ground-based radiation testing of several payload-critical COTS devices used in the SGR payload and describes its on-orbit performance. (authors)

A New Algorithm for ABS/GPS Integration Based on Fuzzy-Logic in Vehicle Navigation System

Directory of Open Access Journals (Sweden)

Ali Amin Zadeh

2011-10-01

Full Text Available GPS based vehicle navigation systems have difficulties in tracking vehicles in urban canyons due to poor satellite availability. ABS (Antilock Brake System Navigation System consists of self-contained optical encoders mounted on vehicle wheels that can continuously provide accurate short-term positioning information. In this paper, a new concept regarding GPS/ABS integration, based on Fuzzy Logic is presented. The proposed algorithm is used to identify GPS position accuracy based on environment and vehicle dynamic knowledge. The GPS is used as reference during the time it is in a good condition and replaced by ABS positioning system when GPS information is unreliable. We compare our proposed algorithm with other common algorithm in real environment. Our results show that the proposed algorithm can significantly improve the stability and reliability of ABS/GPS navigation system.

Development of a High Precision Displacement Measurement System by Fusing a Low Cost RTK-GPS Sensor and a Force Feedback Accelerometer for Infrastructure Monitoring

Directory of Open Access Journals (Sweden)

Gunhee Koo

2017-11-01

Full Text Available A displacement measurement system fusing a low cost real-time kinematic global positioning system (RTK-GPS receiver and a force feedback accelerometer is proposed for infrastructure monitoring. The proposed system is composed of a sensor module, a base module and a computation module. The sensor module consists of a RTK-GPS rover and a force feedback accelerometer, and is installed on a target structure like conventional RTK-GPS sensors. The base module is placed on a rigid ground away from the target structure similar to conventional RTK-GPS bases, and transmits observation messages to the sensor module. Then, the initial acceleration, velocity and displacement responses measured by the sensor module are transmitted to the computation module located at a central monitoring facility. Finally, high precision and high sampling rate displacement, velocity, and acceleration are estimated by fusing the acceleration from the accelerometer, the velocity from the GPS rover, and the displacement from RTK-GPS. Note that the proposed displacement measurement system can measure 3-axis acceleration, velocity as well as displacement in real time. In terms of displacement, the proposed measurement system can estimate dynamic and pseudo-static displacement with a root-mean-square error of 2 mm and a sampling rate of up to 100 Hz. The performance of the proposed system is validated under sinusoidal, random and steady-state vibrations. Field tests were performed on the Yeongjong Grand Bridge and Yi Sun-sin Bridge in Korea, and the Xihoumen Bridge in China to compare the performance of the proposed system with a commercial RTK-GPS sensor and other data fusion techniques.

An Improved Strong Tracking Cubature Kalman Filter for GPS/INS Integrated Navigation Systems.

Science.gov (United States)

Feng, Kaiqiang; Li, Jie; Zhang, Xi; Zhang, Xiaoming; Shen, Chong; Cao, Huiliang; Yang, Yanyu; Liu, Jun

2018-06-12

The cubature Kalman filter (CKF) is widely used in the application of GPS/INS integrated navigation systems. However, its performance may decline in accuracy and even diverge in the presence of process uncertainties. To solve the problem, a new algorithm named improved strong tracking seventh-degree spherical simplex-radial cubature Kalman filter (IST-7thSSRCKF) is proposed in this paper. In the proposed algorithm, the effect of process uncertainty is mitigated by using the improved strong tracking Kalman filter technique, in which the hypothesis testing method is adopted to identify the process uncertainty and the prior state estimate covariance in the CKF is further modified online according to the change in vehicle dynamics. In addition, a new seventh-degree spherical simplex-radial rule is employed to further improve the estimation accuracy of the strong tracking cubature Kalman filter. In this way, the proposed comprehensive algorithm integrates the advantage of 7thSSRCKF’s high accuracy and strong tracking filter’s strong robustness against process uncertainties. The GPS/INS integrated navigation problem with significant dynamic model errors is utilized to validate the performance of proposed IST-7thSSRCKF. Results demonstrate that the improved strong tracking cubature Kalman filter can achieve higher accuracy than the existing CKF and ST-CKF, and is more robust for the GPS/INS integrated navigation system.

Evaluation of Mobile Phone Interference With Aircraft GPS Navigation Systems

Science.gov (United States)

Pace, Scott; Oria, A. J.; Guckian, Paul; Nguyen, Truong X.

2004-01-01

This report compiles and analyzes tests that were conducted to measure cell phone spurious emissions in the Global Positioning System (GPS) radio frequency band that could affect the navigation system of an aircraft. The cell phone in question had, as reported to the FAA (Federal Aviation Administration), caused interference to several GPS receivers on-board a small single engine aircraft despite being compliant with data filed at the time with the FCC by the manufacturer. NASA (National Aeronautics and Space Administration) and industry tests show that while there is an emission in the 1575 MHz GPS band due to a specific combination of amplifier output impedance and load impedance that induces instability in the power amplifier, these spurious emissions (i.e., not the intentional transmit signal) are similar to those measured on non-intentionally transmitting devices such as, for example, laptop computers. Additional testing on a wide sample of different commercial cell phones did not result in any emission in the 1575 MHz GPS Band above the noise floor of the measurement receiver.

Assessing the Performance of GPS Precise Point Positioning Under Different Geomagnetic Storm Conditions during Solar Cycle 24

Directory of Open Access Journals (Sweden)

Xiaomin Luo

2018-06-01

Full Text Available The geomagnetic storm, which is an abnormal space weather phenomenon, can sometimes severely affect GPS signal propagation, thereby impacting the performance of GPS precise point positioning (PPP. However, the investigation of GPS PPP accuracy over the global scale under different geomagnetic storm conditions is very limited. This paper for the first time presents the performance of GPS dual-frequency (DF and single-frequency (SF PPP under moderate, intense, and super storms conditions during solar cycle 24 using a large data set collected from about 500 international GNSS services (IGS stations. The global root mean square (RMS maps of GPS PPP results show that stations with degraded performance are mainly distributed at high-latitude, and the degradation level generally depends on the storm intensity. The three-dimensional (3D RMS of GPS DF PPP for high-latitude during moderate, intense, and super storms are 0.393 m, 0.680 m and 1.051 m, respectively, with respect to only 0.163 m on quiet day. RMS errors of mid- and low-latitudes show less dependence on the storm intensities, with values less than 0.320 m, compared to 0.153 m on quiet day. Compared with DF PPP, the performance of GPS SF PPP is inferior regardless of quiet or disturbed conditions. The degraded performance of GPS positioning during geomagnetic storms is attributed to the increased ionospheric disturbances, which have been confirmed by our global rate of TEC index (ROTI maps. Ionospheric disturbances not only lead to the deteriorated ionospheric correction but also to the frequent cycle-slip occurrence. Statistical results show that, compared with that on quiet day, the increased cycle-slip occurrence are 13.04%, 56.52%, and 69.57% under moderate, intense, and super storms conditions, respectively.

Tractor-mounted, GPS-based spot fumigation system manages Prunus replant disease

Directory of Open Access Journals (Sweden)

V. Udompetaikul

2013-10-01

Full Text Available Our research goal was to use recent advances in global positioning system (GPS and computer technology to apply just the right amount of fumigant where it is most needed (i.e., in a small target treatment zone in and around each tree replanting site to control Prunus replant disease (PRD. We developed and confirmed the function of (1 GPS-based software that can be used on cleared orchard land to flexibly plan and map all of an orchard's future tree sites and associated spot fumigation treatment zones and 2 a tractor-based GPS-controlled spot fumigation system to quickly and safely treat the targeted tree site treatment zones. In trials in two almond orchards and one peach orchard, our evaluations of the composite mapping and application system, which examined spatial accuracy of the spot treatments, delivery rate accuracy of the spot treatments, and tree growth responses to the spot treatments, all indicated that GPS spot fumigation has excellent potential to greatly reduce fumigant usage while adequately managing the PRD complex.

GPS Navigation Above 76,000 km for the MMS Mission

Science.gov (United States)

Winternitz, Luke; Bamford, Bill; Price, Samuel; Long, Anne; Farahmand, Mitra; Carpenter, Russell

2016-01-01

NASA's MMS mission, launched in March of 2015,consists of a controlled formation of four spin-stabilized spacecraft in similar highly elliptic orbits reaching apogee at radial distances of 12and 25 Earth radii in the first and second phases of the mission. Navigation for MMS is achieved independently onboard each spacecraft by processing GPS observables using NASA GSFC's Navigator GPS receiver and the Goddard Enhanced Onboard Navigation System (GEONS) extended Kalman filter software. To our knowledge, MMS constitutes, by far, the highest-altitude operational use of GPS to date and represents the culmination of over a decade of high-altitude GPS navigation research and development at NASA GSFC. In this paper we will briefly describe past and ongoing high-altitude GPS research efforts at NASA GSFC and elsewhere, provide details on the design of the MMS GPS navigation system, and present on-orbit performance data. We extrapolate these results to predict performance in the Phase 2b mission orbit, and conclude with a discussion of the implications of the MMS results for future high-altitude GPS navigation, which we believe to be broad and far-reaching.

Use and Protection of GPS Sidelobe Signals for Enhanced Navigation Performance in High Earth Orbit

Science.gov (United States)

Parker, Joel J. K.; Valdez, Jennifer E.; Bauer, Frank H.; Moreau, Michael C.

2016-01-01

GPS (Global Positioning System) Space Service Volume (SSV) signal environment is from 3,000-36,000 kilometers altitude. Current SSV specifications only capture performance provided by signals transmitted within 23.5(L1) or 26(L2-L5) off-nadir angle. Recent on-orbit data lessons learned show significant PNT (Positioning, Navigation and Timing) performance improvements when the full aggregate signal is used. Numerous military civil operational missions in High Geosynchronous Earth Orbit (HEOGEO) utilize the full signal to enhance vehicle PNT performance

IMPELEMENTASI SISTEM PEMANTAUAN OBJEK BERGERAK DENGAN MEMANFAATKAN FREKUENSI RADIO MENGGUNAKAN GPS (GLOBAL POSITIONING SYSTEM

Directory of Open Access Journals (Sweden)

Budi Triandi

2010-05-01

Full Text Available GPS was developed by the United States Department of Defense as a reliable means for accurate navigation. The system provides highly accurate position and velocity information and precise time on a continuous global basis to an unlimited number of properly equipped users. By using combined GPS receiver and microcontroller together with radio system, we can design a monitoring system for our vehicles and display the result on the computer. This system consists of a master module that transmits and receives signals from computer and two slave modules to collect GPS data from vehicles. The result of experiment shows that this system is able to track the vehicle on digital map with accuracy as high as 95%.Keywords: GPS, microcontroller, monitoring, RF

Hybrid Kalman and unscented Kalman filters for INS/GPS integrated system considering constant lever arm effect

Institute of Scientific and Technical Information of China (English)

常国宾; 柳明

2015-01-01

In inertial navigation system (INS) and global positioning system (GPS) integrated system, GPS antennas are usually not located at the same location as the inertial measurement unit (IMU) of the INS, so the lever arm effect exists, which makes the observation equation highly nonlinear. The INS/GPS integration with constant lever arm effect is studied. The position relation of IMU and GPS’s antenna is represented in the earth centered earth fixed frame, while the velocity relation of these two systems is represented in local horizontal frame. Due to the small integration time interval of INS, i.e. 0.1 s in this work, the nonlinearity in the INS error equation is trivial, so the linear INS error model is constructed and addressed by Kalman filter’s prediction step. On the other hand, the high nonlinearity in the observation equation due to lever arm effect is addressed by unscented Kalman filter’s update step to attain higher accuracy and better applicability. Simulation is designed and the performance of the hybrid filter is validated.

Supporting EarthScope Cyber-Infrastructure with a Modern GPS Science Data System

Science.gov (United States)

Webb, F. H.; Bock, Y.; Kedar, S.; Jamason, P.; Fang, P.; Dong, D.; Owen, S. E.; Prawirodirjo, L.; Squibb, M.

2008-12-01

Building on NASA's investment in the measurement of crustal deformation from continuous GPS, we are developing and implementing a Science Data System (SDS) that will provide mature, long-term Earth Science Data Records (ESDR's). This effort supports NASA's Earth Surface and Interiors (ESI) focus area and provide NASA's component to the EarthScope PBO. This multi-year development is sponsored by NASA's Making Earth System data records for Use in Research Environments (MEaSUREs) program. The SDS integrates the generation of ESDRs with data analysis and exploration, product generation, and modeling tools based on daily GPS data that include GPS networks in western North America and a component of NASA's Global GPS Network (GGN) for terrestrial reference frame definition. The system is expandable to multiple regional and global networks. The SDS builds upon mature data production, exploration, and analysis algorithms developed under NASA's REASoN, ACCESS, and SENH programs. This SDS provides access to positions, time series, velocity fields, and strain measurements derived from continuous GPS data obtained at tracking stations in both the Plate Boundary Observatory and other regional Western North America GPS networks, dating back to 1995. The SDS leverages the IT and Web Services developments carried out under the SCIGN/REASoN and ACCESS projects, which have streamlined access to data products for researchers and modelers, and which have created a prototype an on-the-fly interactive research environment through a modern data portal, GPS Explorer. This IT system has been designed using modern IT tools and principles in order to be extensible to any geographic location, scale, natural hazard, and combination of geophysical sensor and related data. We have built upon open GIS standards, particularly those of the OGC, and have used the principles of Web Service-based Service Oriented Architectures to provide scalability and extensibility to new services and capabilities.

Arctic Tides from GPS on sea-ice

DEFF Research Database (Denmark)

Kildegaard Rose, Stine; Skourup, Henriette; Forsberg, René

2013-01-01

The presence of sea-ice in the Arctic Ocean plays a significant role in the Arctic climate. Sea-ice dampens the ocean tide amplitude with the result that global tidal models perform less accurately in the polar regions. This paper presents, a kinematic processing of global positioning system (GPS....... The results show coherence between the GPS buoy measurements, and the tide model. Furthermore, we have proved that the reference ellipsoid of WGS84, can be interpolated to the tidal defined zero level by applying geophysical corrections to the GPS data....

Global Positioning Systems (GPS) Technology to Study Vector-Pathogen-Host Interactions

Science.gov (United States)

2016-12-01

Award Number: W81XWH-11-2-0175 TITLE: Global Positioning Systems (GPS) Technology to Study Vector-Pathogen-Host Interactions PRINCIPAL...Positioning Systems (GPS) Technology to Study Vector-Pathogen-Host Interactions 5b. GRANT NUMBER W81XWH-11-2-0175 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...genetic diversity in the population, in hospitalized children with severe dengue illness and cluster investigation of their neighborhoods, and by using

Adaptive Federal Kalman Filtering for SINS/GPS Integrated System

Institute of Scientific and Technical Information of China (English)

杨勇; 缪玲娟

2003-01-01

A new adaptive federal Kalman filter for a strapdown integrated navigation system/global positioning system (SINS/GPS) is given. The developed federal Kalman filter is based on the trace operation of parameters estimation's error covariance matrix and the spectral radius of update measurement noise variance-covariance matrix for the proper choice of the filter weight and hence the filter gain factors. Theoretical analysis and results from simulation in which the SINS/GPS was compared to conventional Kalman filter are presented. Results show that the algorithm of this adaptive federal Kalman filter is simpler than that of the conventional one. Furthermore, it outperforms the conventional Kalman filter when the system is undertaken measurement malfunctions because of its possession of adaptive ability. This filter can be used in the vehicle integrated navigation system.

Study on index system of GPS interference effect evaluation

Science.gov (United States)

Zhang, Kun; Zeng, Fangling; Zhao, Yuan; Zeng, Ruiqi

2018-05-01

Satellite navigation interference effect evaluation is the key technology to break through the research of Navigation countermeasure. To evaluate accurately the interference degree and Anti-jamming ability of GPS receiver, this text based on the existing research results of Navigation interference effect evaluation, build the index system of GPS receiver effectiveness evaluation from four levels of signal acquisition, tracking, demodulation and positioning/timing and establish the model for each index. These indexes can accurately and quantitatively describe the interference effect at all levels.

Location - Global Positioning System (GPS) Photos

Data.gov (United States)

Army Corps of Engineers, Department of the Army, Department of Defense — Digital photos tagged with GPS location information. The St. Paul District maintains a digital library of over 10,000 GPS photos. Photos are often associated with...

GPS Space Service Volume: Ensuring Consistent Utility Across GPS Design Builds for Space Users

Science.gov (United States)

Bauer, Frank H.; Parker, Joel Jefferson Konkl; Valdez, Jennifer Ellen

2015-01-01

GPS availability and signal strength originally specified for users on or near surface of Earth with transmitted power levels specified at edge-of-Earth, 14.3 degrees. Prior to the SSV specification, on-orbit performance of GPS varied from block build to block build (IIA, IIRM, IIF) due to antenna gain and beam width variances. Unstable on-orbit performance results in significant risk to space users. Side-lobe signals, although not specified, were expected to significantly boost GPS signal availability for users above the constellation. During GPS III Phase A, NASA noted significant discrepancies in power levels specified in GPS III specification documents, and measured on-orbit performance. To stabilize the signal for high altitude space users, NASA DoD team in 2003-2005 led the creation of new Space Service Volume (SSV) definition and specifications.

A novel fusion methodology to bridge GPS outages for land vehicle positioning

International Nuclear Information System (INIS)

Chen, Wei; Li, Xu; Song, Xiang; Xu, Qimin; Li, Bin; Song, Xianghui

2015-01-01

Many intelligent transportation system applications require accurate, reliable, and continuous vehicle position information whether in open-sky environments or in Global Positioning System (GPS) denied environments. However, there remains a challenging task for land vehicles to achieve such positioning performance using low-cost sensors, especially microelectromechanical system (MEMS) sensors. In this paper, a novel and cost-effective fusion methodology to bridge GPS outages is proposed and applied in the Inertial Navigation System (INS)/GPS/ compass integrated positioning system. In the implementation of the proposed methodology, a key data preprocessing algorithm is first developed to eliminate the noise in inertial sensors in order to provide more accurate information for subsequent modeling. Then, a novel hybrid strategy incorporating the designed autoregressive model (AR model)-based forward estimator (ARFE) with Kalman filter (KF) is presented to predict the INS position errors during GPS outages. To verify the feasibility and effectiveness of the proposed methodology, real road tests with various scenarios were performed. The proposed methodology illustrates significant improvement in positioning accuracy during GPS outages. (paper)

Geomagnetic storm effects on GPS based navigation

Directory of Open Access Journals (Sweden)

P. V. S. Rama Rao

2009-05-01

Full Text Available The energetic events on the sun, solar wind and subsequent effects on the Earth's geomagnetic field and upper atmosphere (ionosphere comprise space weather. Modern navigation systems that use radio-wave signals, reflecting from or propagating through the ionosphere as a means of determining range or distance, are vulnerable to a variety of effects that can degrade the performance of the navigational systems. In particular, the Global Positioning System (GPS that uses a constellation of earth orbiting satellites are affected due to the space weather phenomena.

Studies made during two successive geomagnetic storms that occurred during the period from 8 to 12 November 2004, have clearly revealed the adverse affects on the GPS range delay as inferred from the Total Electron Content (TEC measurements made from a chain of seven dual frequency GPS receivers installed in the Indian sector. Significant increases in TEC at the Equatorial Ionization anomaly crest region are observed, resulting in increased range delay during the periods of the storm activity. Further, the storm time rapid changes occurring in TEC resulted in a number of phase slips in the GPS signal compared to those on quiet days. These phase slips often result in the loss of lock of the GPS receivers, similar to those that occur during strong(>10 dB L-band scintillation events, adversely affecting the GPS based navigation.

Crustal Deformation along San Andreas Fault System revealed by GPS and Sentinel-1 InSAR

Science.gov (United States)

Xu, X.; Sandwell, D. T.

2017-12-01

We present a crustal deformation velocity map along the San Andreas Fault System by combining measurements from Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System (GPS) velocity models (CGM V1). We assembled 5 tracks of descending Sentinel-1 InSAR data spanning 2014.11-2017.02, and produced 545 interferograms, each of which covers roughly 250km x 420km area ( 60 bursts). These interferograms are unwrapped using SNAPHU [Chen & Zebker, 2002], with the 2Npi unwrapping ambiguity corrected with a sparse recovery method. We used coherence-based small baseline subset (SBAS) method [Tong & Schmidt, 2016] together with atmospheric correction by common-point stacking [Tymofyeyeva and Fialko, 2015] to construct deformation time series [Xu et. al., 2017]. Then we project the horizontal GPS model and vertical GPS data into satellite line-of-sight directions separately. We first remove the horizontal GPS model from InSAR measurements and perform elevation-dependent atmospheric phase correction. Then we compute the discrepancy between the remaining InSAR measurements and vertical GPS data. We interpolate this discrepancy and remove it from the residual InSAR measurements. Finally, we restore the horizontal GPS model. Preliminary results show that fault creep over the San Jacinto fault, the Elsinore fault, and the San Andreas creeping section is clearly resolved. During the period of drought, the Central Valley of California was subsiding at a high rate (up to 40 cm/yr), while the city of San Jose is uplifting due to recharge, with a quaternary fault acting as a ground water barrier. These findings will be reported during the meeting.

Upper Troposphere Lower Stratosphere structure during convective systems using GPS radio occultations

DEFF Research Database (Denmark)

Biondi, Riccardo

The deep convective systems play a fundamental role in atmospheric circulation and climate. Thunderstorms and meso-scale convective systems produce fast vertical transport, redistributing water vapor and trace gases and influencing the thermal structure of the upper troposphere and lower...... stratosphere (UTLS) contributing to the troposphere-stratosphere transport and affecting the Earth global circulation and the climate changes. The Global Positioning System (GPS) Radio Occultation (RO) technique enables measurement of atmospheric density structure in any meteorological condition...... to the analysis of tropical storms for the future mission ACES will also be evaluated. Using data from the past and ongoing GPS RO missions we have defined an algorithm to detect the clouds top of the convective systems and their thermal structure. Other satellite and in-situ measurements co-located with GPS ROs...

Remote reference processing in MT survey using GPS clock; MT ho ni okeru GPS wo mochiita jikoku doki system

Energy Technology Data Exchange (ETDEWEB)

Yamane, K; Inoue, J; Takasugi, S [Geothermal Energy Research and Development Co. Ltd., Tokyo (Japan); Kosuge, S [DRICO Co. Ltd., Tokyo (Japan)

1996-05-01

A report is given about the application of a synchronizing system using clock signals from GPS satellites to a remote reference method which is a technique to reject noise from the MT method. This system uses the C/A code out of the L1 band waves from NAVSTAR/GPS satellites. The new system was operated in MT method-using investigations conducted at China Peninsula, Aichi Prefecture, and Izu Peninsula, Shizuoka Prefecture, with the reference points placed several 100km away in Iwate Prefecture on both occasions. It was found as the result that it is basically possible to catch signals from the GPS at any place, that the signals are accurate enough to be applied to time synchronization for the MT method, and that the signals assure a far remote reference method with a separation of several 100km between the sites involved. The referencing process at high frequencies whose feasibility had been doubted proved a success when highly correlated signals were exchanged between two stations over a distance of several 100km. 5 refs., 9 figs.

Evaluation of a regional real-time precise positioning system based on GPS/BeiDou observations in Australia

Science.gov (United States)

Ding, Wenwu; Tan, Bingfeng; Chen, Yongchang; Teferle, Felix Norman; Yuan, Yunbin

2018-02-01

The performance of real-time (RT) precise positioning can be improved by utilizing observations from multiple Global Navigation Satellite Systems (GNSS) instead of one particular system. Since the end of 2012, BeiDou, independently established by China, began to provide operational services for users in the Asia-Pacific regions. In this study, a regional RT precise positioning system is developed to evaluate the performance of GPS/BeiDou observations in Australia in providing high precision positioning services for users. Fixing three hourly updated satellite orbits, RT correction messages are generated and broadcasted by processing RT observation/navigation data streams from the national network of GNSS Continuously Operating Reference Stations in Australia (AUSCORS) at the server side. At the user side, RT PPP is realized by processing RT data streams and the RT correction messages received. RT clock offsets, for which the accuracy reached 0.07 and 0.28 ns for GPS and BeiDou, respectively, can be determined. Based on these corrections, an accuracy of 12.2, 30.0 and 45.6 cm in the North, East and Up directions was achieved for the BeiDou-only solution after 30 min while the GPS-only solution reached 5.1, 15.3 and 15.5 cm for the same components at the same time. A further improvement of 43.7, 36.9 and 45.0 percent in the three directions, respectively, was achieved for the combined GPS/BeiDou solution. After the initialization process, the North, East and Up positioning accuracies were 5.2, 8.1 and 17.8 cm, respectively, for the BeiDou-only solution, while 1.5, 3.0, and 4.7 cm for the GPS-only solution. However, we only noticed a 20.9% improvement in the East direction was obtained for the GPS/BeiDou solution, while no improvements in the other directions were detected. It is expected that such improvements may become bigger with the increasing accuracy of the BeiDou-only solution.

GNSS global navigation satellite systems : GPS, GLONASS, Galileo, and more

CERN Document Server

Hofmann-Wellenhof, Bernhard; Wasle, Elmar

2008-01-01

This book is an extension to the acclaimed scientific bestseller "GPS - Theory and Practice". It covers Global Navigation Satellite Systems (GNSS) and includes the Russian GLONASS, the European system Galileo, and additional systems.

Reduced variability and execution time to reach a target with a needle GPS system: Comparison between physicians, residents and nurse anaesthetists.

Science.gov (United States)

Fevre, Marie-Cécile; Vincent, Caroline; Picard, Julien; Vighetti, Arnaud; Chapuis, Claire; Detavernier, Maxime; Allenet, Benoît; Payen, Jean-François; Bosson, Jean-Luc; Albaladejo, Pierre

2018-02-01

Ultrasound (US) guided needle positioning is safer than anatomical landmark techniques for central venous access. Hand-eye coordination and execution time depend on the professional's ability, previous training and personal skills. Needle guidance positioning systems (GPS) may theoretically reduce execution time and facilitate needle positioning in specific targets, thus improving patient comfort and safety. Three groups of healthcare professionals (41 anaesthesiologists and intensivists, 41 residents in anaesthesiology and intensive care, 39 nurse anaesthetists) were included and required to perform 3 tasks (positioning the tip of a needle in three different targets in a silicon phantom) by using successively a conventional US-guided needle positioning and a needle GPS. We measured execution times to perform the tasks, hand-eye coordination and the number of repositioning occurrences or errors in handling the needle or the probe. Without the GPS system, we observed a significant inter-individual difference for execution time (Pgaming were found to be independent factors associated with a shorter execution time. Use of GPS attenuated the inter-individual and group variability. We observed a reduced execution time and improved hand-eye coordination in all groups as compared to US without GPS. Neither US training, video gaming nor demographic personal or professional factors were found to be significantly associated with reduced execution time when GPS was used. US associated with GPS systems may improve safety and decrease execution time by reducing inter-individual variability between professionals for needle-handling procedures. Copyright © 2016 Société française d'anesthésie et de réanimation (Sfar). Published by Elsevier Masson SAS. All rights reserved.

GPS test range mission planning

Science.gov (United States)

Roberts, Iris P.; Hancock, Thomas P.

The principal features of the Test Range User Mission Planner (TRUMP), a PC-resident tool designed to aid in deploying and utilizing GPS-based test range assets, are reviewed. TRUMP features time history plots of time-space-position information (TSPI); performance based on a dynamic GPS/inertial system simulation; time history plots of TSPI data link connectivity; digital terrain elevation data maps with user-defined cultural features; and two-dimensional coverage plots of ground-based test range assets. Some functions to be added during the next development phase are discussed.

A Mobile GPS Application: Mosque Tracking with Prayer Time Synchronization

Science.gov (United States)

Hashim, Rathiah; Ikhmatiar, Mohammad Sibghotulloh; Surip, Miswan; Karmin, Masiri; Herawan, Tutut

Global Positioning System (GPS) is a popular technology applied in many areas and embedded in many devices, facilitating end-users to navigate effectively to user's intended destination via the best calculated route. The ability of GPS to track precisely according to coordinates of specific locations can be utilized to assist a Muslim traveler visiting or passing an unfamiliar place to find the nearest mosque in order to perform his prayer. However, not many techniques have been proposed for Mosque tracking. This paper presents the development of GPS technology in tracking the nearest mosque using mobile application software embedded with the prayer time's synchronization system on a mobile application. The prototype GPS system developed has been successfully incorporated with a map and several mosque locations.

The limits of direct satellite tracking with the Global Positioning System (GPS)

Science.gov (United States)

Bertiger, W. I.; Yunck, T. P.

1988-01-01

Recent advances in high precision differential Global Positioning System-based satellite tracking can be applied to the more conventional direct tracking of low earth satellites. To properly evaluate the limiting accuracy of direct GPS-based tracking, it is necessary to account for the correlations between the a-priori errors in GPS states, Y-bias, and solar pressure parameters. These can be obtained by careful analysis of the GPS orbit determination process. The analysis indicates that sub-meter accuracy can be readily achieved for a user above 1000 km altitude, even when the user solution is obtained with data taken 12 hours after the data used in the GPS orbit solutions.

Map matching and heuristic elimination of gyro drift for personal navigation systems in GPS-denied conditions

International Nuclear Information System (INIS)

Aggarwal, Priyanka; Thomas, David; Ojeda, Lauro; Borenstein, Johann

2011-01-01

This paper introduces a method for the substantial reduction of heading errors in inertial navigation systems used under GPS-denied conditions. Presumably, the method is applicable for both vehicle-based and personal navigation systems, but experiments were performed only with a personal navigation system called 'personal dead reckoning' (PDR). In order to work under GPS-denied conditions, the PDR system uses a foot-mounted inertial measurement unit (IMU). However, gyro drift in this IMU can cause large heading errors after just a few minutes of walking. To reduce these errors, the map-matched heuristic drift elimination (MAPHDE) method was developed, which estimates gyro drift errors by comparing IMU-derived heading to the direction of the nearest street segment in a database of street maps. A heuristic component in this method provides tolerance to short deviations from walking along the street, such as when crossing streets or intersections. MAPHDE keeps heading errors almost at zero, and, as a result, position errors are dramatically reduced. In this paper, MAPHDE was used in a variety of outdoor walks, without any use of GPS. This paper explains the MAPHDE method in detail and presents experimental results

Implementation of a GPS-RO data processing system for the KIAPS-LETKF data assimilation system

Science.gov (United States)

Kwon, H.; Kang, J.-S.; Jo, Y.; Kang, J. H.

2015-03-01

The Korea Institute of Atmospheric Prediction Systems (KIAPS) has been developing a new global numerical weather prediction model and an advanced data assimilation system. As part of the KIAPS package for observation processing (KPOP) system for data assimilation, preprocessing, and quality control modules for bending-angle measurements of global positioning system radio occultation (GPS-RO) data have been implemented and examined. The GPS-RO data processing system is composed of several steps for checking observation locations, missing values, physical values for Earth radius of curvature, and geoid undulation. An observation-minus-background check is implemented by use of a one-dimensional observational bending-angle operator, and tangent point drift is also considered in the quality control process. We have tested GPS-RO observations utilized by the Korean Meteorological Administration (KMA) within KPOP, based on both the KMA global model and the National Center for Atmospheric Research Community Atmosphere Model with Spectral Element dynamical core (CAM-SE) as a model background. Background fields from the CAM-SE model are incorporated for the preparation of assimilation experiments with the KIAPS local ensemble transform Kalman filter (LETKF) data assimilation system, which has been successfully implemented to a cubed-sphere model with unstructured quadrilateral meshes. As a result of data processing, the bending-angle departure statistics between observation and background show significant improvement. Also, the first experiment in assimilating GPS-RO bending angle from KPOP within KIAPS-LETKF shows encouraging results.

LIDAR AND INS FUSION IN PERIODS OF GPS OUTAGES FOR MOBILE LASER SCANNING MAPPING SYSTEMS

Directory of Open Access Journals (Sweden)

I. Klein

2012-09-01

Full Text Available Mobile laser scanning systems are becoming an increasingly popular means to obtain 3D coverage on a large scale. To perform the mapping, the exact position of the vehicle must be known throughout the trajectory. Exact position is achieved via integration of Global Positioning Systems (GPS and Inertial Navigation Systems (INS. Yet, in urban environments, cases of complete or even partial GPS outages may occur leaving the navigation solution to rely only on the INS. The INS navigation solution degrades with time as the Inertial Measurement Unit (IMU measurements contains noise, which permeates into the navigation equations. Degradation of the position determination leads to loss of data in such segments. To circumvent such drift and its effects, we propose fusing INS with lidar data by using building edges. This detection of edges is then translated into position data, which is used as an aiding to the INS. It thereby enables the determination of the vehicle position with a satisfactory level accuracy, sufficient to perform the laser-scanning based mapping in those outage periods.

Profile of English salaried GPs: labour mobility and practice performance.

Science.gov (United States)

Ding, Alexander; Hann, Mark; Sibbald, Bonnie

2008-01-01

Recent national policy changes have provided greater flexibility in GPs' contracts. One such policy is salaried employment, which offers reduced hours and freedom from out-of-hours and administrative responsibilities, aimed at improving recruitment and retention in a labour market facing regional shortages. To profile salaried GPs and assess their mobility within the labour market. Serial cross-sectional study. All GPs practising in England during the years 1996/1997, 2000/2001, and 2004/2005. Descriptive analyses, logistic regression. Salaried GPs tended to be either younger ( or =65 years), female, or overseas-qualified; they favoured part-time working and personal medical services contracts. Salaried GPs were more mobile than GP principals, and have become increasingly so, despite a trend towards reduced overall mobility in the GP workforce. Practices with salaried GPs scored more Quality and Outcomes Framework points and were located in slightly more affluent areas. Salaried status appears to have reduced limitations in the labour market, leading to better workforce deployment from a GP's perspective. However, there is no evidence to suggest it has relieved inequalities in GP distribution.

A transportation security system applying RFID and GPS

Directory of Open Access Journals (Sweden)

Ruijian Zhang

2013-03-01

Full Text Available Purpose: This paper is about developing a centralized, internet based security tool which utilizes RFID and GPS technology to identify drivers and track the load integrity. Design/methodology/approach: The system will accomplish the security testing in real-time using the internet and the U.S. Customs’ database (ACE. A central database and the interfaces and communication between the database and ACE will be established. After the vehicle is loaded, all openings of the tanker are sealed with disposable RFID tag seals. Findings/value: An RFID reader and GPS tracker wirelessly connected with the databases will serve as testing grounds for the implementation of security measures that can help prevent future terrorist attacks and help in ensuring that the goods and products are not compromised while in transit. The system will also reduce the labor work of security check to its minimum. 

Performance evaluation of ionospheric time delay forecasting models using GPS observations at a low-latitude station

Science.gov (United States)

Sivavaraprasad, G.; Venkata Ratnam, D.

2017-07-01

Ionospheric delay is one of the major atmospheric effects on the performance of satellite-based radio navigation systems. It limits the accuracy and availability of Global Positioning System (GPS) measurements, related to critical societal and safety applications. The temporal and spatial gradients of ionospheric total electron content (TEC) are driven by several unknown priori geophysical conditions and solar-terrestrial phenomena. Thereby, the prediction of ionospheric delay is challenging especially over Indian sub-continent. Therefore, an appropriate short/long-term ionospheric delay forecasting model is necessary. Hence, the intent of this paper is to forecast ionospheric delays by considering day to day, monthly and seasonal ionospheric TEC variations. GPS-TEC data (January 2013-December 2013) is extracted from a multi frequency GPS receiver established at K L University, Vaddeswaram, Guntur station (geographic: 16.37°N, 80.37°E; geomagnetic: 7.44°N, 153.75°E), India. An evaluation, in terms of forecasting capabilities, of three ionospheric time delay models - an Auto Regressive Moving Average (ARMA) model, Auto Regressive Integrated Moving Average (ARIMA) model, and a Holt-Winter's model is presented. The performances of these models are evaluated through error measurement analysis during both geomagnetic quiet and disturbed days. It is found that, ARMA model is effectively forecasting the ionospheric delay with an accuracy of 82-94%, which is 10% more superior to ARIMA and Holt-Winter's models. Moreover, the modeled VTEC derived from International Reference Ionosphere, IRI (IRI-2012) model and new global TEC model, Neustrelitz TEC Model (NTCM-GL) have compared with forecasted VTEC values of ARMA, ARIMA and Holt-Winter's models during geomagnetic quiet days. The forecast results are indicating that ARMA model would be useful to set up an early warning system for ionospheric disturbances at low latitude regions.

Autonomous GPS/INS navigation experiment for Space Transfer Vehicle

Science.gov (United States)

Upadhyay, Triveni N.; Cotterill, Stephen; Deaton, A. W.

1993-01-01

An experiment to validate the concept of developing an autonomous integrated spacecraft navigation system using on board Global Positioning System (GPS) and Inertial Navigation System (INS) measurements is described. The feasibility of integrating GPS measurements with INS measurements to provide a total improvement in spacecraft navigation performance, i.e. improvement in position, velocity and attitude information, was previously demonstrated. An important aspect of this research is the automatic real time reconfiguration capability of the system designed to respond to changes in a spacecraft mission under the control of an expert system.

Global positioning systems (GPS) and microtechnology sensors in team sports: a systematic review.

Science.gov (United States)

Cummins, Cloe; Orr, Rhonda; O'Connor, Helen; West, Cameron

2013-10-01

Use of Global positioning system (GPS) technology in team sport permits measurement of player position, velocity, and movement patterns. GPS provides scope for better understanding of the specific and positional physiological demands of team sport and can be used to design training programs that adequately prepare athletes for competition with the aim of optimizing on-field performance. The objective of this study was to conduct a systematic review of the depth and scope of reported GPS and microtechnology measures used within individual sports in order to present the contemporary and emerging themes of GPS application within team sports. A systematic review of the application of GPS technology in team sports was conducted. We systematically searched electronic databases from earliest record to June 2012. Permutations of key words included GPS; male and female; age 12-50 years; able-bodied; and recreational to elite competitive team sports. The 35 manuscripts meeting the eligibility criteria included 1,276 participants (age 11.2-31.5 years; 95 % males; 53.8 % elite adult athletes). The majority of manuscripts reported on GPS use in various football codes: Australian football league (AFL; n = 8), soccer (n = 7), rugby union (n = 6), and rugby league (n = 6), with limited representation in other team sports: cricket (n = 3), hockey (n = 3), lacrosse (n = 1), and netball (n = 1). Of the included manuscripts, 34 (97 %) detailed work rate patterns such as distance, relative distance, speed, and accelerations, with only five (14.3 %) reporting on impact variables. Activity profiles characterizing positional play and competitive levels were also described. Work rate patterns were typically categorized into six speed zones, ranging from 0 to 36.0 km·h⁻¹, with descriptors ranging from walking to sprinting used to identify the type of activity mainly performed in each zone. With the exception of cricket, no standardized speed zones or definitions were observed within or

Geomagnetic storms, super-storms, and their impacts on GPS-based navigation systems

Science.gov (United States)

Astafyeva, E.; Yasyukevich, Yu.; Maksikov, A.; Zhivetiev, I.

2014-07-01

Using data of GPS receivers located worldwide, we analyze the quality of GPS performance during four geomagnetic storms of different intensity: two super-storms and two intense storms. We show that during super-storms the density of GPS Losses-of-Lock (LoL) increases up to 0.25% at L1 frequency and up to 3% at L2 frequency, and up to 0.15% (at L1) and 1% (at L2) during less intense storms. Also, depending on the intensity of the storm time ionospheric disturbances, the total number of total electron content (TEC) slips can exceed from 4 to 40 times the quiet time level. Both GPS LoL and TEC slips occur during abrupt changes of SYM-H index of geomagnetic activity, i.e., during the main phase of geomagnetic storms and during development of ionospheric storms. The main contribution in the total number of GPS LoL was found to be done by GPS sites located at low and high latitudes, whereas the area of numerous TEC slips seemed to mostly correspond to the boundary of the auroral oval, i.e., region with intensive ionospheric irregularities. Our global maps of TEC slips show where the regions with intense irregularities of electron density occur during geomagnetic storms and will let us in future predict appearance of GPS errors for geomagnetically disturbed conditions.

Real-Time Vehicle Data Logging System Using GPS And GSM

Directory of Open Access Journals (Sweden)

Win Minn Thet

2015-07-01

Full Text Available Abstract This paper proposes and implements a low cost Vehicle Data Logging System using GPS and GSM. This system allows a user to trace the present and past positions recorded in SD card. This system also reads the current position of the vehicle using GPS the data is sent via GSM service from the GSM network. The vehicles position including the driving speed the UTC time and data are stored in the SD card for live and past tracking. All of that GPS data is sent to PIC 18F4520 by the Universal Asynchronous ReceiverTransmitter UART and also store in SD card. GSM also uses UART to transmit. To know the position of the vehicle the owner sends a request through a SMS. The SMS sends to the authorized person through the GSM network. The travel history of the vehicle are stored in a file on an SD card in FAT format.This system is very useful for car tracking for adolescent driver being checked by parent speed limit exceeding leaving a specific area. V The developed system is easy to use requires no additional hardware and permits the selection of the amount of data and the time intervals between the data recordings. In addition the collected data can easily be transferred to a computer via a connected serial port.

Seamless Guidance System Combining GPS, BLE Beacon, and NFC Technologies

Directory of Open Access Journals (Sweden)

Rung-Shiang Cheng

2016-01-01

Full Text Available Users rely increasingly on Location-Based Services (LBS and automated navigation/guidance systems nowadays. However, while such services are easily implemented in outdoor environments using Global Positioning System (GPS technology, a requirement still exists for accurate localization and guidance schemes in indoor settings. Accordingly, the present study proposes a system based on GPS, Bluetooth Low Energy (BLE beacons, and Near Field Communication (NFC technology. Through establishing graphic information and the design of algorithm, this study develops a guidance system for indoors and outdoors on smart phones, wishing to give user perfect smart life through this system. The proposed system is implemented on a smart phone and evaluated on a student campus environment. The experimental results confirm the ability of the proposed app to switch automatically from an outdoor mode to an indoor mode and to guide the user to requested target destination via the shortest possible route.

A Self-Tuning Kalman Filter for Autonomous Navigation using the Global Positioning System (GPS)

Science.gov (United States)

Truong, S. H.

1999-01-01

Most navigation systems currently operated by NASA are ground-based, and require extensive support to produce accurate results. Recently developed systems that use Kalman filter and GPS data for orbit determination greatly reduce dependency on ground support, and have potential to provide significant economies for NASA spacecraft navigation. These systems, however, still rely on manual tuning from analysts. A sophisticated neuro-fuzzy component fully integrated with the flight navigation system can perform the self-tuning capability for the Kalman filter and help the navigation system recover from estimation errors in real time.

Nonlinear Filtering with IMM Algorithm for Ultra-Tight GPS/INS Integration

Directory of Open Access Journals (Sweden)

Dah-Jing Jwo

2013-05-01

Full Text Available Abstract This paper conducts a performance evaluation for the ultra-tight integration of a Global positioning system (GPS and an inertial navigation system (INS, using nonlinear filtering approaches with an interacting multiple model (IMM algorithm. An ultra-tight GPS/INS architecture involves the integration of in-phase and quadrature components from the correlator of a GPS receiver with INS data. An unscented Kalman filter (UKF, which employs a set of sigma points by deterministic sampling, avoids the error caused by linearization as in an extended Kalman filter (EKF. Based on the filter structural adaptation for describing various dynamic behaviours, the IMM nonlinear filtering provides an alternative for designing the adaptive filter in the ultra-tight GPS/INS integration. The use of IMM enables tuning of an appropriate value for the process of noise covariance so as to maintain good estimation accuracy and tracking capability. Two examples are provided to illustrate the effectiveness of the design and demonstrate the effective improvement in navigation estimation accuracy. A performance comparison among various filtering methods for ultra-tight integration of GPS and INS is also presented. The IMM based nonlinear filtering approach demonstrates the effectiveness of the algorithm for improved positioning performance.

Software Defined GPS Receiver for International Space Station

Science.gov (United States)

Duncan, Courtney B.; Robison, David E.; Koelewyn, Cynthia Lee

2011-01-01

JPL is providing a software defined radio (SDR) that will fly on the International Space Station (ISS) as part of the CoNNeCT project under NASA's SCaN program. The SDR consists of several modules including a Baseband Processor Module (BPM) and a GPS Module (GPSM). The BPM executes applications (waveforms) consisting of software components for the embedded SPARC processor and logic for two Virtex II Field Programmable Gate Arrays (FPGAs) that operate on data received from the GPSM. GPS waveforms on the SDR are enabled by an L-Band antenna, low noise amplifier (LNA), and the GPSM that performs quadrature downconversion at L1, L2, and L5. The GPS waveform for the JPL SDR will acquire and track L1 C/A, L2C, and L5 GPS signals from a CoNNeCT platform on ISS, providing the best GPS-based positioning of ISS achieved to date, the first use of multiple frequency GPS on ISS, and potentially the first L5 signal tracking from space. The system will also enable various radiometric investigations on ISS such as local multipath or ISS dynamic behavior characterization. In following the software-defined model, this work will create a highly portable GPS software and firmware package that can be adapted to another platform with the necessary processor and FPGA capability. This paper also describes ISS applications for the JPL CoNNeCT SDR GPS waveform, possibilities for future global navigation satellite system (GNSS) tracking development, and the applicability of the waveform components to other space navigation applications.

Applying GPS to enhance understanding of transport-related physical activity.

Science.gov (United States)

Duncan, Mitch J; Badland, Hannah M; Mummery, W Kerry

2009-09-01

The purpose of the paper is to review the utility of the global positioning system (GPS) in the study of health-related physical activity. The paper draws from existing literature to outline the current work performed using GPS to examine transport-related physical activity, with a focus on the relative utility of the approach when combined with geographic information system (GIS) and other data sources including accelerometers. The paper argues that GPS, especially when used in combination with GIS and accelerometery, offers great promise in objectively measuring and studying the relationship of numerous environmental attributes to human behaviour in terms of physical activity and transport-related activity. Limitations to the use of GPS for the purpose of monitoring health-related physical activity are presented, and recommendations for future avenues of research are discussed.

Novel Hybrid of LS-SVM and Kalman Filter for GPS/INS Integration

Science.gov (United States)

Xu, Zhenkai; Li, Yong; Rizos, Chris; Xu, Xiaosu

Integration of Global Positioning System (GPS) and Inertial Navigation System (INS) technologies can overcome the drawbacks of the individual systems. One of the advantages is that the integrated solution can provide continuous navigation capability even during GPS outages. However, bridging the GPS outages is still a challenge when Micro-Electro-Mechanical System (MEMS) inertial sensors are used. Methods being currently explored by the research community include applying vehicle motion constraints, optimal smoother, and artificial intelligence (AI) techniques. In the research area of AI, the neural network (NN) approach has been extensively utilised up to the present. In an NN-based integrated system, a Kalman filter (KF) estimates position, velocity and attitude errors, as well as the inertial sensor errors, to output navigation solutions while GPS signals are available. At the same time, an NN is trained to map the vehicle dynamics with corresponding KF states, and to correct INS measurements when GPS measurements are unavailable. To achieve good performance it is critical to select suitable quality and an optimal number of samples for the NN. This is sometimes too rigorous a requirement which limits real world application of NN-based methods.The support vector machine (SVM) approach is based on the structural risk minimisation principle, instead of the minimised empirical error principle that is commonly implemented in an NN. The SVM can avoid local minimisation and over-fitting problems in an NN, and therefore potentially can achieve a higher level of global performance. This paper focuses on the least squares support vector machine (LS-SVM), which can solve highly nonlinear and noisy black-box modelling problems. This paper explores the application of the LS-SVM to aid the GPS/INS integrated system, especially during GPS outages. The paper describes the principles of the LS-SVM and of the KF hybrid method, and introduces the LS-SVM regression algorithm. Field

Implementing GPS into Pave-IR.

Science.gov (United States)

2009-03-01

To further enhance the capabilities of the Pave-IR thermal segregation detection system developed at the Texas Transportation Institute, researchers incorporated global positioning system (GPS) data collection into the thermal profiles. This GPS capa...

GPS Navigation and Tracking Device

Directory of Open Access Journals (Sweden)

Yahya Salameh Khraisat

2011-10-01

Full Text Available Since the introduction of GPS Navigation systems in the marketplace, consumers and businesses have been coming up with innovative ways to use the technology in their everyday life. GPS Navigation and Tracking systems keep us from getting lost when we are in strange locations, they monitor children when they are away from home, keep track of business vehicles and can even let us know where a philandering partner is at all times. Because of this we attend to build a GPS tracking device to solve the mentioned problems. Our work consists of the GPS module that collects data from satellites and calculates the position information before transmitting them to the user’s PC (of Navigation system or observers (of Tracking System using wireless technology (GSM.

GPS: Public Utility or Software Platform

Science.gov (United States)

2016-09-01

train for GPS loss, encourage use of GPS signal integrity monitors , develop in- vehicle GPS backups, and evaluate the range of radio...literature prevent the full quantification of exactly how vulnerable GPS is to service interruption. This thesis used constant comparison analysis to...criticality, resilience, and vulnerability. This methodology overcomes research limitations by using GPS system design, operations, and policies as

Autonomous GPS/INS navigation experiment for Space Transfer Vehicle (STV)

Science.gov (United States)

Upadhyay, Triveni N.; Cotterill, Stephen; Deaton, A. Wayne

1991-01-01

An experiment to validate the concept of developing an autonomous integrated spacecraft navigation system using on board Global Positioning System (GPS) and Inertial Navigation System (INS) measurements is described. The feasibility of integrating GPS measurements with INS measurements to provide a total improvement in spacecraft navigation performance, i.e. improvement in position, velocity and attitude information, was previously demonstrated. An important aspect of this research is the automatic real time reconfiguration capability of the system designed to respond to changes in a spacecraft mission under the control of an expert system.

A web-based GPS system for displacement monitoring and failure mechanism analysis of reservoir landslide.

Science.gov (United States)

Li, Yuanyao; Huang, Jinsong; Jiang, Shui-Hua; Huang, Faming; Chang, Zhilu

2017-12-07

It is important to monitor the displacement time series and to explore the failure mechanism of reservoir landslide for early warning. Traditionally, it is a challenge to monitor the landslide displacements real-timely and automatically. Globe Position System (GPS) is considered as the best real-time monitoring technology, however, the accuracies of the landslide displacements monitored by GPS are not assessed effectively. A web-based GPS system is developed to monitor the landslide displacements real-timely and automatically in this study. And the discrete wavelet transform (DWT) is proposed to assess the accuracy of the GPS monitoring displacements. Wangmiao landslide in Three Gorges Reservoir area in China is used as case study. The results show that the web-based GPS system has advantages of high precision, real-time, remote control and automation for landslide monitoring; the Root Mean Square Errors of the monitoring landslide displacements are less than 5 mm. Meanwhile, the results also show that a rapidly falling reservoir water level can trigger the reactivation of Wangmiao landslide. Heavy rainfall is also an important factor, but not a crucial component.

Tracking Small Satellites using Translated GPS

OpenAIRE

Lefevre, Don; Mulally, Daniel

1991-01-01

This paper discusses using translated GPS for tracking small satellites, the technical trade-offs involved, and the position and timing accuracies which are achievable using translated GPS. The Global Positioning System (GPS) uses the relative times-of-arrival of multiple spread-spectrum signals at an antenna to determine the position of the antenna. The system can also determine the time the antenna was at that position. The direct sequence spread spectrum signals are transmitted from GPS sa...

The International GPS Service (IGS) as a Continuous Reference System for Precise GPS Positioning

Science.gov (United States)

Neilan, Ruth; Heflin, Michael; Watkins, Michael; Zumberge, James

1996-01-01

The International GPS Service for Geodynamics (IGS) is an organization which operates under the auspices of the International Association of Geodesy (IAG) and has been operational since January 1994. The primary objective of the IGS is to provide precise GPS data and data products to support geodetic and geophysical research activities.

Military/Civilian Mixed-Mode Global Positioning System (GPS) Receiver (MMGR)

National Research Council Canada - National Science Library

Peczalski, Andy; Kriz, Jeff; Carlson, Stephen G; Sampson, Steven J

2004-01-01

... AND T) MMGR objective of meeting pervasive defense system requirements and civilian needs for ultra-small GPS receiver technology is dependent in part upon the creation of multi- L-band reconfigurable...

IMPELEMENTASI SISTEM PEMANTAUAN OBJEK BERGERAK DENGAN MEMANFAATKAN FREKUENSI RADIO MENGGUNAKAN GPS (GLOBAL POSITIONING SYSTEM)

OpenAIRE

Budi Triandi

2010-01-01

GPS was developed by the United States Department of Defense as a reliable means for accurate navigation. The system provides highly accurate position and velocity information and precise time on a continuous global basis to an unlimited number of properly equipped users. By using combined GPS receiver and microcontroller together with radio system, we can design a monitoring system for our vehicles and display the result on the computer. This system consists of a master module that transmits...

On the Realistic Stochastic Model of GPS Observables: Implementation and Performance

Science.gov (United States)

Zangeneh-Nejad, F.; Amiri-Simkooei, A. R.; Sharifi, M. A.; Asgari, J.

2015-12-01

High-precision GPS positioning requires a realistic stochastic model of observables. A realistic GPS stochastic model of observables should take into account different variances for different observation types, correlations among different observables, the satellite elevation dependence of observables precision, and the temporal correlation of observables. Least-squares variance component estimation (LS-VCE) is applied to GPS observables using the geometry-based observation model (GBOM). To model the satellite elevation dependent of GPS observables precision, an exponential model depending on the elevation angles of the satellites are also employed. Temporal correlation of the GPS observables is modelled by using a first-order autoregressive noise model. An important step in the high-precision GPS positioning is double difference integer ambiguity resolution (IAR). The fraction or percentage of success among a number of integer ambiguity fixing is called the success rate. A realistic estimation of the GNSS observables covariance matrix plays an important role in the IAR. We consider the ambiguity resolution success rate for two cases, namely a nominal and a realistic stochastic model of the GPS observables using two GPS data sets collected by the Trimble R8 receiver. The results confirm that applying a more realistic stochastic model can significantly improve the IAR success rate on individual frequencies, either on L1 or on L2. An improvement of 20% was achieved to the empirical success rate results. The results also indicate that introducing the realistic stochastic model leads to a larger standard deviation for the baseline components by a factor of about 2.6 on the data sets considered.

Indoor/Outdoor Seamless Positioning Using Lighting Tags and GPS Cellular Phones for Personal Navigation

Science.gov (United States)

Namie, Hiromune; Morishita, Hisashi

The authors focused on the development of an indoor positioning system which is easy to use, portable and available for everyone. This system is capable of providing the correct position anywhere indoors, including onboard ships, and was invented in order to evaluate the availability of GPS indoors. Although the performance of GPS is superior outdoors, there has been considerable research regarding indoor GPS involving sensitive GPS, pseudolites (GPS pseudo satellite), RFID (Radio Frequency IDentification) tags, and wireless LAN .However, the positioning rate and the precision are not high enough for general use, which is the reason why these technologies have not yet spread to personal navigation systems. In this regard, the authors attempted to implement an indoor positioning system using cellular phones with built-in GPS and infrared light data communication functionality, which are widely used in Japan. GPS is becoming increasingly popular, where GPGGS sentences of the NMEA outputted from the GPS receiver provide spatiotemporal information including latitude, longitude, altitude, and time or ECEF xyz coordinates. As GPS applications grow rapidly, spatiotemporal data becomes key to the ubiquitous outdoor and indoor seamless positioning services at least for the entire area of Japan, as well as to becoming familiar with satellite positioning systems (e.g. GPS). Furthermore, the authors are also working on the idea of using PDAs (Personal Digital Assistants), as cellular phones with built-in GPS and PDA functionality are also becoming increasingly popular.

A comparison between different error modeling of MEMS applied to GPS/INS integrated systems.

Science.gov (United States)

Quinchia, Alex G; Falco, Gianluca; Falletti, Emanuela; Dovis, Fabio; Ferrer, Carles

2013-07-24

Advances in the development of micro-electromechanical systems (MEMS) have made possible the fabrication of cheap and small dimension accelerometers and gyroscopes, which are being used in many applications where the global positioning system (GPS) and the inertial navigation system (INS) integration is carried out, i.e., identifying track defects, terrestrial and pedestrian navigation, unmanned aerial vehicles (UAVs), stabilization of many platforms, etc. Although these MEMS sensors are low-cost, they present different errors, which degrade the accuracy of the navigation systems in a short period of time. Therefore, a suitable modeling of these errors is necessary in order to minimize them and, consequently, improve the system performance. In this work, the most used techniques currently to analyze the stochastic errors that affect these sensors are shown and compared: we examine in detail the autocorrelation, the Allan variance (AV) and the power spectral density (PSD) techniques. Subsequently, an analysis and modeling of the inertial sensors, which combines autoregressive (AR) filters and wavelet de-noising, is also achieved. Since a low-cost INS (MEMS grade) presents error sources with short-term (high-frequency) and long-term (low-frequency) components, we introduce a method that compensates for these error terms by doing a complete analysis of Allan variance, wavelet de-nosing and the selection of the level of decomposition for a suitable combination between these techniques. Eventually, in order to assess the stochastic models obtained with these techniques, the Extended Kalman Filter (EKF) of a loosely-coupled GPS/INS integration strategy is augmented with different states. Results show a comparison between the proposed method and the traditional sensor error models under GPS signal blockages using real data collected in urban roadways.

Miniaturized GPS/MEMS IMU integrated board

Science.gov (United States)

Lin, Ching-Fang (Inventor)

2012-01-01

This invention documents the efforts on the research and development of a miniaturized GPS/MEMS IMU integrated navigation system. A miniaturized GPS/MEMS IMU integrated navigation system is presented; Laser Dynamic Range Imager (LDRI) based alignment algorithm for space applications is discussed. Two navigation cameras are also included to measure the range and range rate which can be integrated into the GPS/MEMS IMU system to enhance the navigation solution.

A Simultaneously Calibration Approach for Installation and Attitude Errors of an INS/GPS/LDS Target Tracker

Directory of Open Access Journals (Sweden)

Jianhua Cheng

2015-02-01

Full Text Available To obtain the absolute position of a target is one of the basic topics for non-cooperated target tracking problems. In this paper, we present a simultaneously calibration method for an Inertial navigation system (INS/Global position system (GPS/Laser distance scanner (LDS integrated system based target positioning approach. The INS/GPS integrated system provides the attitude and position of observer, and LDS offers the distance between the observer and the target. The two most significant errors are taken into jointly consideration and analyzed: (1 the attitude measure error of INS/GPS; (2 the installation error between INS/GPS and LDS subsystems. Consequently, a INS/GPS/LDS based target positioning approach considering these two errors is proposed. In order to improve the performance of this approach, a novel calibration method is designed to simultaneously estimate and compensate these two main errors. Finally, simulations are conducted to access the performance of the proposed target positioning approach and the designed simultaneously calibration method.

A simultaneously calibration approach for installation and attitude errors of an INS/GPS/LDS target tracker.

Science.gov (United States)

Cheng, Jianhua; Chen, Daidai; Sun, Xiangyu; Wang, Tongda

2015-02-04

To obtain the absolute position of a target is one of the basic topics for non-cooperated target tracking problems. In this paper, we present a simultaneously calibration method for an Inertial navigation system (INS)/Global position system (GPS)/Laser distance scanner (LDS) integrated system based target positioning approach. The INS/GPS integrated system provides the attitude and position of observer, and LDS offers the distance between the observer and the target. The two most significant errors are taken into jointly consideration and analyzed: (1) the attitude measure error of INS/GPS; (2) the installation error between INS/GPS and LDS subsystems. Consequently, a INS/GPS/LDS based target positioning approach considering these two errors is proposed. In order to improve the performance of this approach, a novel calibration method is designed to simultaneously estimate and compensate these two main errors. Finally, simulations are conducted to access the performance of the proposed target positioning approach and the designed simultaneously calibration method.

In-flight performance analysis of MEMS GPS receiver and its application to precise orbit determination of APOD-A satellite

Science.gov (United States)

Gu, Defeng; Liu, Ye; Yi, Bin; Cao, Jianfeng; Li, Xie

2017-12-01

An experimental satellite mission termed atmospheric density detection and precise orbit determination (APOD) was developed by China and launched on 20 September 2015. The micro-electro-mechanical system (MEMS) GPS receiver provides the basis for precise orbit determination (POD) within the range of a few decimetres. The in-flight performance of the MEMS GPS receiver was assessed. The average number of tracked GPS satellites is 10.7. However, only 5.1 GPS satellites are available for dual-frequency navigation because of the loss of many L2 observations at low elevations. The variations in the multipath error for C1 and P2 were estimated, and the maximum multipath error could reach up to 0.8 m. The average code noises are 0.28 m (C1) and 0.69 m (P2). Using the MEMS GPS receiver, the orbit of the APOD nanosatellite (APOD-A) was precisely determined. Two types of orbit solutions are proposed: a dual-frequency solution and a single-frequency solution. The antenna phase center variations (PCVs) and code residual variations (CRVs) were estimated, and the maximum value of the PCVs is 4.0 cm. After correcting the antenna PCVs and CRVs, the final orbit precision for the dual-frequency and single-frequency solutions were 7.71 cm and 12.91 cm, respectively, validated using the satellite laser ranging (SLR) data, which were significantly improved by 3.35 cm and 25.25 cm. The average RMS of the 6-h overlap differences in the dual-frequency solution between two consecutive days in three dimensions (3D) is 4.59 cm. The MEMS GPS receiver is the Chinese indigenous onboard receiver, which was successfully used in the POD of a nanosatellite. This study has important reference value for improving the MEMS GPS receiver and its application in other low Earth orbit (LEO) nanosatellites.

GPS Estimates of Integrated Precipitable Water Aid Weather Forecasters

Science.gov (United States)

Moore, Angelyn W.; Gutman, Seth I.; Holub, Kirk; Bock, Yehuda; Danielson, David; Laber, Jayme; Small, Ivory

2013-01-01

Global Positioning System (GPS) meteorology provides enhanced density, low-latency (30-min resolution), integrated precipitable water (IPW) estimates to NOAA NWS (National Oceanic and Atmospheric Adminis tration Nat ional Weather Service) Weather Forecast Offices (WFOs) to provide improved model and satellite data verification capability and more accurate forecasts of extreme weather such as flooding. An early activity of this project was to increase the number of stations contributing to the NOAA Earth System Research Laboratory (ESRL) GPS meteorology observing network in Southern California by about 27 stations. Following this, the Los Angeles/Oxnard and San Diego WFOs began using the enhanced GPS-based IPW measurements provided by ESRL in the 2012 and 2013 monsoon seasons. Forecasters found GPS IPW to be an effective tool in evaluating model performance, and in monitoring monsoon development between weather model runs for improved flood forecasting. GPS stations are multi-purpose, and routine processing for position solutions also yields estimates of tropospheric zenith delays, which can be converted into mm-accuracy PWV (precipitable water vapor) using in situ pressure and temperature measurements, the basis for GPS meteorology. NOAA ESRL has implemented this concept with a nationwide distribution of more than 300 "GPSMet" stations providing IPW estimates at sub-hourly resolution currently used in operational weather models in the U.S.

GPS on Every Roof, GPS Sensor Network for Post-Seismic Building-Wise Damage Identification

Directory of Open Access Journals (Sweden)

Kenji Oguni

2013-12-01

Full Text Available Development of wireless sensor network equipped with GPS for post-seismic building-wise damage identification is presented in this paper. This system is called GPS on Every Roof. Sensor node equipped with GPS antenna and receiver is installed on the top of the roof of each and every building. The position of this sensor node is measured before and after earthquake. The final goal of this system is to i identify the displacement of the roof of each house and ii collect the information of displacement of the roof of the houses through wireless communication. Superposing this information on GIS, building-wise damage distribution due to earthquake can be obtained. The system overview, hardware and some of the key components of the system such as on-board GPS relative positioning algorithm to achieve the accuracy in the order of several centimeters are described in detail. Also, the results from a field experiment using a wireless sensor network with 39 sensor nodes are presented.

A Real Time Differential GPS Tracking System for NASA Sounding Rockets

Science.gov (United States)

Bull, Barton; Bauer, Frank (Technical Monitor)

2000-01-01

Sounding rockets are suborbital launch vehicles capable of carrying scientific payloads to several hundred miles in altitude. These missions return a variety of scientific data including: chemical makeup and physical processes taking place in the atmosphere, natural radiation surrounding the Earth, data on the Sun, stars, galaxies and many other phenomena. In addition, sounding rockets provide a reasonably economical means of conducting engineering tests for instruments and devices to be used on satellites and other spacecraft prior to their use in these more expensive missions. Typically around thirty of these rockets are launched each year, from established ranges at Wallops Island, Virginia; Poker Flat Research Range, Alaska; White Sands Missile Range, New Mexico and from a number of ranges outside the United States. Many times launches are conducted from temporary launch ranges in remote parts of the world requiring considerable expense to transport and operate tracking radars. In order to support these missions, an inverse differential GPS system has been developed. The flight system consists of a small, inexpensive receiver, a preamplifier and a wrap-around antenna. A rugged, compact, portable ground station extracts GPS data from the raw payload telemetry stream, performs a real time differential solution and graphically displays the rocket's path relative to a predicted trajectory plot. In addition to generating a real time navigation solution, the system has been used for payload recovery, timing, data timetagging, precise tracking of multiple payloads and slaving of optical tracking systems for over the horizon acquisition. This paper discusses, in detail, the flight and ground hardware, as well as data processing and operational aspects of the system, and provides evidence of the system accuracy.

GPS Technology for the Development of Business Information Systems

Directory of Open Access Journals (Sweden)

Mihaela MURESAN

2006-01-01

Full Text Available The use of the GPS system opens the way for a new generation of information systems using geospatial information. The geoinformation provided by the GPS system could be used in various applications, such as: positioning and monitoring the behavior of the objects static or in movement, navigating, measuring the surfaces etc. These new approach introduces the concept of image handling for decision support which involves a better geoimage handling in order to make easier for decision makers to discover, access, and integrate geospatial information in decision-support scenarios. A very useful application is the risk management for the vehicles with direct benefits in terms of competitivity, for the transport organizations, and of road transport safety, for the society. The safety of the road transport is a priority in the light of the policy on trans-European networks for transport (TEN-T and according to the actual and future trend related to the freight on the road (75% of the freight goes by road according to the Third report on Economic and social Cohesion, February 2004. The implementation of a high technology solution based on GPS communication for the monitoring of transports along the whole itinerary and the immediate alert in case of various non-procedural behavior, increases the road transport security and avoids accidents and disasters. Minimizing the risk for the road transport is a general concern at the EU level, as well as at the national level. The design and the development of transport risk management information systems will contribute to stimulate the implementation of the new technologies in the current transport organizations' activity and to change the internal processes according to the philosophy introduced by the information society. The transport risk management system integrates detection and communication intelligent equipment, various communication technologies and networking solutions with powerful computers and

Integrating GPS, GYRO, vehicle speed sensor, and digital map to provide accurate and real-time position in an intelligent navigation system

Science.gov (United States)

Li, Qingquan; Fang, Zhixiang; Li, Hanwu; Xiao, Hui

2005-10-01

The global positioning system (GPS) has become the most extensively used positioning and navigation tool in the world. Applications of GPS abound in surveying, mapping, transportation, agriculture, military planning, GIS, and the geosciences. However, the positional and elevation accuracy of any given GPS location is prone to error, due to a number of factors. The applications of Global Positioning System (GPS) positioning is more and more popular, especially the intelligent navigation system which relies on GPS and Dead Reckoning technology is developing quickly for future huge market in China. In this paper a practical combined positioning model of GPS/DR/MM is put forward, which integrates GPS, Gyro, Vehicle Speed Sensor (VSS) and digital navigation maps to provide accurate and real-time position for intelligent navigation system. This model is designed for automotive navigation system making use of Kalman filter to improve position and map matching veracity by means of filtering raw GPS and DR signals, and then map-matching technology is used to provide map coordinates for map displaying. In practical examples, for illustrating the validity of the model, several experiments and their results of integrated GPS/DR positioning in intelligent navigation system will be shown for the conclusion that Kalman Filter based GPS/DR integrating position approach is necessary, feasible and efficient for intelligent navigation application. Certainly, this combined positioning model, similar to other model, can not resolve all situation issues. Finally, some suggestions are given for further improving integrated GPS/DR/MM application.

A Comparison between Different Error Modeling of MEMS Applied to GPS/INS Integrated Systems

Directory of Open Access Journals (Sweden)

Fabio Dovis

2013-07-01

Full Text Available Advances in the development of micro-electromechanical systems (MEMS have made possible the fabrication of cheap and small dimension accelerometers and gyroscopes, which are being used in many applications where the global positioning system (GPS and the inertial navigation system (INS integration is carried out, i.e., identifying track defects, terrestrial and pedestrian navigation, unmanned aerial vehicles (UAVs, stabilization of many platforms, etc. Although these MEMS sensors are low-cost, they present different errors, which degrade the accuracy of the navigation systems in a short period of time. Therefore, a suitable modeling of these errors is necessary in order to minimize them and, consequently, improve the system performance. In this work, the most used techniques currently to analyze the stochastic errors that affect these sensors are shown and compared: we examine in detail the autocorrelation, the Allan variance (AV and the power spectral density (PSD techniques. Subsequently, an analysis and modeling of the inertial sensors, which combines autoregressive (AR filters and wavelet de-noising, is also achieved. Since a low-cost INS (MEMS grade presents error sources with short-term (high-frequency and long-term (low-frequency components, we introduce a method that compensates for these error terms by doing a complete analysis of Allan variance, wavelet de-nosing and the selection of the level of decomposition for a suitable combination between these techniques. Eventually, in order to assess the stochastic models obtained with these techniques, the Extended Kalman Filter (EKF of a loosely-coupled GPS/INS integration strategy is augmented with different states. Results show a comparison between the proposed method and the traditional sensor error models under GPS signal blockages using real data collected in urban roadways.

Rip current monitoring using GPS buoy system

Science.gov (United States)

Song, DongSeob; Kim, InHo; Kang, DongSoo

2014-05-01

The occurrence of rip current in the Haeundae beach, which is one of the most famous beaches in South Korea, has been threatening beach-goers security in summer season annually. Many coastal scientists have been investigating rip currents by using field observations and measurements, laboratory measurements and wave tank experiments, and computer and numerical modeling. Rip current velocity is intermittent and may rapidly increase within minutes due to larger incoming wave groups or nearshore circulation instabilities. It is important to understand that changes in rip current velocity occur in response to changes in incoming wave height and period as well as changes in water level. GPS buoys have been used to acquire sea level change data, atmospheric parameters and other oceanic variables in sea for the purposes of vertical datum determination, tide correction, radar altimeter calibration, ocean environment and marine pollution monitoring. Therefore, we adopted GPS buoy system for an experiment which is to investigate rip current velocity; it is sporadic and may quickly upsurge within minutes due to larger arriving wave groups or nearshore flow uncertainties. In this study, for high accurate positioning of buy equipment, a Satellite Based Argumentation System DGPS data logger was deployed to investigate within floating object, and it can be acquired three-dimensional coordinate or geodetic position of buoy with continuous NMEA-0183 protocol during 24 hours. The wave height measured by in-situ hydrometer in a cross-shore array clearly increased before and after occurrence of rip current, and wave period also was lengthened around an event. These results show that wave height and period correlate reasonably well with long-shore current interaction in the Haeundae beach. Additionally, current meter data and GPS buoy data showed that rip current velocities, about 0.2 m/s, may become dangerously strong under specific conditions. Acknowledgement This research was

Two laboratory methods for the calibration of GPS speed meters

International Nuclear Information System (INIS)

Bai, Yin; Sun, Qiao; Du, Lei; Yu, Mei; Bai, Jie

2015-01-01

The set-ups of two calibration systems are presented to investigate calibration methods of GPS speed meters. The GPS speed meter calibrated is a special type of high accuracy speed meter for vehicles which uses Doppler demodulation of GPS signals to calculate the measured speed of a moving target. Three experiments are performed: including simulated calibration, field-test signal replay calibration, and in-field test comparison with an optical speed meter. The experiments are conducted at specific speeds in the range of 40–180 km h −1 with the same GPS speed meter as the device under calibration. The evaluation of measurement results validates both methods for calibrating GPS speed meters. The relative deviations between the measurement results of the GPS-based high accuracy speed meter and those of the optical speed meter are analyzed, and the equivalent uncertainty of the comparison is evaluated. The comparison results justify the utilization of GPS speed meters as reference equipment if no fewer than seven satellites are available. This study contributes to the widespread use of GPS-based high accuracy speed meters as legal reference equipment in traffic speed metrology. (paper)

Development of a GPS buoy system for monitoring tsunami, sea waves, ocean bottom crustal deformation and atmospheric water vapor

Science.gov (United States)

Kato, Teruyuki; Terada, Yukihiro; Nagai, Toshihiko; Koshimura, Shun'ichi

2010-05-01

We have developed a GPS buoy system for monitoring tsunami for over 12 years. The idea was that a buoy equipped with a GPS antenna and placed offshore may be an effective way of monitoring tsunami before its arrival to the coast and to give warning to the coastal residents. The key technology for the system is real-time kinematic (RTK) GPS technology. We have successfully developed the system; we have detected tsunamis of about 10cm in height for three large earthquakes, namely, the 23 June 2001 Peru earthquake (Mw8.4), the 26 September 2003 Tokachi earthquake (Mw8.3) and the 5 September 2004 earthquake (Mw7.4). The developed GPS buoy system is also capable of monitoring sea waves that are mainly caused by winds. Only the difference between tsunami and sea waves is their frequency range and can be segregated each other by a simple filtering technique. Given the success of GPS buoy experiments, the system has been adopted as a part of the Nationwide Ocean Wave information system for Port and HArborS (NOWPHAS) by the Ministry of Land, Infrastructure, Transport and Tourism of Japan. They have established more than eight GPS buoys along the Japanese coasts and the system has been operated by the Port and Airport Research Institute. As a future scope, we are now planning to implement some other additional facilities for the GPS buoy system. The first application is a so-called GPS/Acoustic system for monitoring ocean bottom crustal deformation. The system requires acoustic waves to detect ocean bottom reference position, which is the geometrical center of an array of transponders, by measuring distances between a position at the sea surface (vessel) and ocean bottom equipments to return the received sonic wave. The position of the vessel is measured using GPS. The system was first proposed by a research group at the Scripps Institution of Oceanography in early 1980's. The system was extensively developed by Japanese researchers and is now capable of detecting ocean

Evidential recovery from GPS devices

Directory of Open Access Journals (Sweden)

Brian Cusack

Full Text Available Global Positioning Systems (GPS have become more affordable, are now widely used in motor vehicles and in other frequently used applications. As a consequence GPS are increasingly becoming an important source of evidential data for digital forensic investigations. This paper acknowledges there are only disparate documents for the guidance of an investigator when extracting evidence form such systems. The focus of this paper is to provide the technical details of recovering artifacts from four GPS currently available to the New Zealand market. Navman brand GPS are used, following a forensically robust process. The steps of the process are described, results analysed and the associated risks are discussed. In addition, the paper discusses techniques related to the visual presentation of evidence suitable for Google Maps. Automation attempts to speed up the analysis to visualization steps are also included. The outcome is a road map that may assist digital forensic investigators develop GPS examination strategies for implementation in their own organizations.

Precise GPS orbits for geodesy

Science.gov (United States)

Colombo, Oscar L.

1994-01-01

The Global Positioning System (GPS) has become, in recent years, the main space-based system for surveying and navigation in many military, commercial, cadastral, mapping, and scientific applications. Better receivers, interferometric techniques (DGPS), and advances in post-processing methods have made possible to position fixed or moving receivers with sub-decimeter accuracies in a global reference frame. Improved methods for obtaining the orbits of the GPS satellites have played a major role in these achievements; this paper gives a personal view of the main developments in GPS orbit determination.

Evaluating the performance of a low-cost GPS in precision agriculture applications

DEFF Research Database (Denmark)

Jensen, Kjeld; Larsen, Morten; Simonsen, Tom

2012-01-01

Field Robots are often equipped with a Real Time Kinematic (RTK) GPS to obtain precise positioning. In many precision agriculture applications, however, the robot operates in semi-structured environments like orchards and row crops, where local sensors such as computer vision and laser range...... scanners can produce accurate positioning relative to the crops. GPS is then primarily needed for robust inter-row navigation. This work evaluates a new low-cost GPS. Static tests were used to test the absolute accuracy. To test the GPS in a precision agriculture environment it was installed on a robot...

Wireless GPS fleet tracking system at the University of Albany.

Science.gov (United States)

2014-07-01

This report provides an overview of the project undertaken at the University at Albany to make alternative transportation a more : viable option by implementing a GPS Tracking System on the University bus fleet and broadcasting the bus locations to c...

Ionospheric Scintillation Effects on GPS

Science.gov (United States)

Steenburgh, R. A.; Smithtro, C.; Groves, K.

2007-12-01

. Ionospheric scintillation of Global Positioning System (GPS) signals threatens navigation and military operations by degrading performance or making GPS unavailable. Scintillation is particularly active, although not limited to, a belt encircling the earth within 20 degrees of the geomagnetic equator. As GPS applications and users increases, so does the potential for detrimental impacts from scintillation. We examined amplitude scintillation data spanning seven years from Ascension Island, U.K.; Ancon, Peru; and Antofagasta, Chile in the Atlantic/Americas longitudinal sector at as well as data from Parepare, Indonesia; Marak Parak, Malaysia; Pontianak, Indonesia; Guam; and Diego Garcia, U.K.; in the Pacific longitudinal sector. From these data, we calculate percent probability of occurrence of scintillation at various intensities described by the S4 index. Additionally, we determine Dilution of Precision at one minute resolution. We examine diurnal, seasonal and solar cycle characteristics and make spatial comparisons. In general, activity was greatest during the equinoxes and solar maximum, although scintillation at Antofagasta, Chile was higher during 1998 rather than at solar maximum.

Multiple Interference Cancellation Performance for GPS Receivers with Dual-Polarized Antenna Arrays

Directory of Open Access Journals (Sweden)

Moeness G. Amin

2008-11-01

Full Text Available This paper examines the interference cancellation performance in global positioning system (GPS receivers equipped with dual-polarized antenna arrays. In dense jamming environment, different types of interferers can be mitigated by the dual-polarized antennas, either acting individually or in conjunction with other receiver antennas. We apply minimum variance distorntionless response (MVDR method to a uniform circular dual-polarized antenna array. The MVDR beamformer is constructed for each satellite. Analysis of the eigenstructures of the covariance matrix and the corresponding weight vector polarization characteristics are provided. Depending on the number of jammers and jammer polarizations, the array chooses to expend its degrees of freedom to counter the jammer polarization or/and use phase coherence to form jammer spatial nulls. Results of interference cancellations demonstrate that applying multiple MVDR beamformers, each for one satellite, has a superior cancellation performance compared to using only one MVDR beamformer for all satellites in the field of view.

A GPS Sensing Strategy for Accurate and Energy-Efficient Outdoor-to-Indoor Handover in Seamless Localization Systems

Directory of Open Access Journals (Sweden)

Yungeun Kim

2012-01-01

Full Text Available Indoor localization systems typically locate users on their own local coordinates, while outdoor localization systems use global coordinates. To achieve seamless localization from outdoors to indoors, a handover technique that accurately provides a starting position to the indoor localization system is needed. However, existing schemes assume that a starting position is known a priori or uses a naïve approach to consider the last location obtained from GPS as the handover point. In this paper, we propose an accurate handover scheme that monitors the signal-to-noise ratio (SNR of the effective GPS satellites that are selected according to their altitude. We also propose an energy-efficient handover mechanism that reduces the GPS sampling interval gradually. Accuracy and energy efficiency are experimentally validated with the GPS logs obtained in real life.

GPS Position Time Series @ JPL

Science.gov (United States)

Owen, Susan; Moore, Angelyn; Kedar, Sharon; Liu, Zhen; Webb, Frank; Heflin, Mike; Desai, Shailen

2013-01-01

Different flavors of GPS time series analysis at JPL - Use same GPS Precise Point Positioning Analysis raw time series - Variations in time series analysis/post-processing driven by different users. center dot JPL Global Time Series/Velocities - researchers studying reference frame, combining with VLBI/SLR/DORIS center dot JPL/SOPAC Combined Time Series/Velocities - crustal deformation for tectonic, volcanic, ground water studies center dot ARIA Time Series/Coseismic Data Products - Hazard monitoring and response focused center dot ARIA data system designed to integrate GPS and InSAR - GPS tropospheric delay used for correcting InSAR - Caltech's GIANT time series analysis uses GPS to correct orbital errors in InSAR - Zhen Liu's talking tomorrow on InSAR Time Series analysis

The EVS: a computerized decision support system for GPs in the Netherlands.

NARCIS (Netherlands)

Wolters, I.; Hoogen, H. van den; Bakker, D. de

2003-01-01

Background: In 1998 a project was started to introduce nationally a decision support system in general practice in the Netherlands, called EVS (electronic prescription support system). The system contains national guidelines developed by the Dutch Council of GPs (NHG) for approximately 80 diagnoses.

Integrated INS/GPS Navigation from a Popular Perspective

Science.gov (United States)

Omerbashich, Mensur

2002-01-01

Inertial navigation, blended with other navigation aids, Global Positioning System (GPS) in particular, has gained significance due to enhanced navigation and inertial reference performance and dissimilarity for fault tolerance and anti-jamming. Relatively new concepts based upon using Differential GPS (DGPS) blended with Inertial (and visual) Navigation Sensors (INS) offer the possibility of low cost, autonomous aircraft landing. The FAA has decided to implement the system in a sophisticated form as a new standard navigation tool during this decade. There have been a number of new inertial sensor concepts in the recent past that emphasize increased accuracy of INS/GPS versus INS and reliability of navigation, as well as lower size and weight, and higher power, fault tolerance, and long life. The principles of GPS are not discussed; rather the attention is directed towards general concepts and comparative advantages. A short introduction to the problems faced in kinematics is presented. The intention is to relate the basic principles of kinematics to probably the most used navigation method in the future-INS/GPS. An example of the airborne INS is presented, with emphasis on how it works. The discussion of the error types and sources in navigation, and of the role of filters in optimal estimation of the errors then follows. The main question this paper is trying to answer is 'What are the benefits of the integration of INS and GPS and how is this, navigation concept of the future achieved in reality?' The main goal is to communicate the idea about what stands behind a modern navigation method.

75 FR 8928 - Announcement of IS-GPS-200, IS-GPS-705, IS-GPS-800 Interface Control Working Group (ICWG...

Science.gov (United States)

2010-02-26

... DEPARTMENT OF DEFENSE Department of the Air Force Announcement of IS-GPS-200, IS-GPS-705, IS-GPS... document/s IS-GPS-200E (NAVSTAR GPS Space Segment/Navigation User Interfaces), IS-GPS-705A (NAVSTAR GPS Space Segment/User Segment L5 Interfaces), and IS-GPS-800A (NAVSTAR GPS Space Segment/User Segment L1C...

Tightly coupled low cost 3D RISS/GPS integration using a mixture particle filter for vehicular navigation.

Science.gov (United States)

Georgy, Jacques; Noureldin, Aboelmagd

2011-01-01

Satellite navigation systems such as the global positioning system (GPS) are currently the most common technique used for land vehicle positioning. However, in GPS-denied environments, there is an interruption in the positioning information. Low-cost micro-electro mechanical system (MEMS)-based inertial sensors can be integrated with GPS and enhance the performance in denied GPS environments. The traditional technique for this integration problem is Kalman filtering (KF). Due to the inherent errors of low-cost MEMS inertial sensors and their large stochastic drifts, KF, with its linearized models, has limited capabilities in providing accurate positioning. Particle filtering (PF) was recently suggested as a nonlinear filtering technique to accommodate for arbitrary inertial sensor characteristics, motion dynamics and noise distributions. An enhanced version of PF called the Mixture PF is utilized in this study to perform tightly coupled integration of a three dimensional (3D) reduced inertial sensors system (RISS) with GPS. In this work, the RISS consists of one single-axis gyroscope and a two-axis accelerometer used together with the vehicle's odometer to obtain 3D navigation states. These sensors are then integrated with GPS in a tightly coupled scheme. In loosely-coupled integration, at least four satellites are needed to provide acceptable GPS position and velocity updates for the integration filter. The advantage of the tightly-coupled integration is that it can provide GPS measurement update(s) even when the number of visible satellites is three or lower, thereby improving the operation of the navigation system in environments with partial blockages by providing continuous aiding to the inertial sensors even during limited GPS satellite availability. To effectively exploit the capabilities of PF, advanced modeling for the stochastic drift of the vertically aligned gyroscope is used. In order to benefit from measurement updates for such drift, which are

Tightly Coupled Low Cost 3D RISS/GPS Integration Using a Mixture Particle Filter for Vehicular Navigation

Directory of Open Access Journals (Sweden)

Jacques Georgy

2011-04-01

Full Text Available Satellite navigation systems such as the global positioning system (GPS are currently the most common technique used for land vehicle positioning. However, in GPS-denied environments, there is an interruption in the positioning information. Low-cost micro-electro mechanical system (MEMS-based inertial sensors can be integrated with GPS and enhance the performance in denied GPS environments. The traditional technique for this integration problem is Kalman filtering (KF. Due to the inherent errors of low-cost MEMS inertial sensors and their large stochastic drifts, KF, with its linearized models, has limited capabilities in providing accurate positioning. Particle filtering (PF was recently suggested as a nonlinear filtering technique to accommodate for arbitrary inertial sensor characteristics, motion dynamics and noise distributions. An enhanced version of PF called the Mixture PF is utilized in this study to perform tightly coupled integration of a three dimensional (3D reduced inertial sensors system (RISS with GPS. In this work, the RISS consists of one single-axis gyroscope and a two-axis accelerometer used together with the vehicle’s odometer to obtain 3D navigation states. These sensors are then integrated with GPS in a tightly coupled scheme. In loosely-coupled integration, at least four satellites are needed to provide acceptable GPS position and velocity updates for the integration filter. The advantage of the tightly-coupled integration is that it can provide GPS measurement update(s even when the number of visible satellites is three or lower, thereby improving the operation of the navigation system in environments with partial blockages by providing continuous aiding to the inertial sensors even during limited GPS satellite availability. To effectively exploit the capabilities of PF, advanced modeling for the stochastic drift of the vertically aligned gyroscope is used. In order to benefit from measurement updates for such drift

Estimation of heading gyrocompass error using a GPS 3DF system: Impact on ADCP measurements

Directory of Open Access Journals (Sweden)

Simón Ruiz

2002-12-01

Full Text Available Traditionally the horizontal orientation in a ship (heading has been obtained from a gyrocompass. This instrument is still used on research vessels but has an estimated error of about 2-3 degrees, inducing a systematic error in the cross-track velocity measured by an Acoustic Doppler Current Profiler (ADCP. The three-dimensional positioning system (GPS 3DF provides an independent heading measurement with accuracy better than 0.1 degree. The Spanish research vessel BIO Hespérides has been operating with this new system since 1996. For the first time on this vessel, the data from this new instrument are used to estimate gyrocompass error. The methodology we use follows the scheme developed by Griffiths (1994, which compares data from the gyrocompass and the GPS system in order to obtain an interpolated error function. In the present work we apply this methodology on mesoscale surveys performed during the observational phase of the OMEGA project, in the Alboran Sea. The heading-dependent gyrocompass error dominated. Errors in gyrocompass heading of 1.4-3.4 degrees have been found, which give a maximum error in measured cross-track ADCP velocity of 24 cm s-1.

Design of γ-ray vehicle patrol system based on GPS

International Nuclear Information System (INIS)

Zhang Wen; Li Changjin

2011-01-01

In order to detect the radiation in the surrounding environment of Nuclear facilities in a wide range, the γ-Ray vehicle patrol system based radiation on GPS and composed of γ-Ray detection terminal and PC is designed. The γ-Ray detection terminal uses controller ATmega128L as control core, detecting the radiation intensity of γ-Ray with G-M counter tube and getting the location with GPS module LR9548S, packing a data frame with γ-Ray radiation and location information according to the agreed protocol which will be sent to PC through UART interface; The PC can processes, display and analyze the data, backup to database Access2003, also can paint the measuring track and distributed picture of radiation intensity. The system can be equipped with a variety of vehicles for mobile patrol to use in the fields of searching radioactive sources, emergency monitoring and measurement of environmental radiation levels. (authors)

GPS Interference Mitigation Using Derivative-free Kalman Filter-based RNN

Directory of Open Access Journals (Sweden)

W. L. Mao

2016-09-01

Full Text Available The global positioning system (GPS with accurate positioning and timing properties has become integral part of all applications around the world. Radio frequency interference can significantly decrease the performance of GPS receivers or even completely prohibit the acquisition or tracking of satellites. The approaches of system performances that can be further enhanced by preprocessing to reject the jamming signal will be investigated. A recurrent neural network (RNN predictor for the GPS anti-jamming applications will be proposed. The adaptive RNN predictor is utilized to accurately predict the narrowband waveform based on an unscented Kalman filter (UKF-based algorithm. The UKF algorithm as a derivative-free alternative to the extended Kalman filter (EKF in the framework of state-estimation is adopted to achieve better performance in terms of convergence rate and quality of solution. The adaptive RNN filter can be successfully applied for the suppression of interference with a number of different narrowband formats, i.e. continuous wave interference (CWI, multi-tone CWI, swept CWI and pulsed CWI, to emulate realistic circumstances. Simulation results show that the proposed UKF-based scheme can offer the superior performances to suppress the interference over the conventional methods by computing mean squared prediction error (MSPE and signal-to-noise ratio (SNR improvements.

Applications of GPS technologies to field sports.

Science.gov (United States)

Aughey, Robert J

2011-09-01

Global positioning system (GPS) technology was made possible after the invention of the atomic clock. The first suggestion that GPS could be used to assess the physical activity of humans followed some 40 y later. There was a rapid uptake of GPS technology, with the literature concentrating on validation studies and the measurement of steady-state movement. The first attempts were made to validate GPS for field sport applications in 2006. While GPS has been validated for applications for team sports, some doubts continue to exist on the appropriateness of GPS for measuring short high-velocity movements. Thus, GPS has been applied extensively in Australian football, cricket, hockey, rugby union and league, and soccer. There is extensive information on the activity profile of athletes from field sports in the literature stemming from GPS, and this includes total distance covered by players and distance in velocity bands. Global positioning systems have also been applied to detect fatigue in matches, identify periods of most intense play, different activity profiles by position, competition level, and sport. More recent research has integrated GPS data with the physical capacity or fitness test score of athletes, game-specific tasks, or tactical or strategic information. The future of GPS analysis will involve further miniaturization of devices, longer battery life, and integration of other inertial sensor data to more effectively quantify the effort of athletes.

Design and implementation of the GPS subsystem for the Radio Aurora eXplorer

Science.gov (United States)

Spangelo, Sara C.; Bennett, Matthew W.; Meinzer, Daniel C.; Klesh, Andrew T.; Arlas, Jessica A.; Cutler, James W.

2013-06-01

This paper presents the design and implementation of the Global Positioning System (GPS) subsystem for the Radio Aurora eXplorer (RAX) CubeSat. The GPS subsystem provides accurate temporal and spatial information necessary to satisfy the science objectives of the RAX mission. There are many challenges in the successful design and implementation of a GPS subsystem for a CubeSat-based mission, including power, size, mass, and financial constraints. This paper presents an approach for selecting and testing the individual and integrated GPS subsystem components, including the receiver, antenna, low noise amplifier, and supporting circuitry. The procedures to numerically evaluate the GPS link budget and test the subsystem components at various stages of system integration are described. Performance results for simulated tests in the terrestrial and orbital environments are provided, including start-up times, carrier-to-noise ratios, and orbital position accuracy. Preliminary on-orbit GPS results from the RAX-1 and RAX-2 spacecraft are presented to validate the design process and pre-flight simulations. Overall, this paper provides a systematic approach to aid future satellite designers in implementing and verifying GPS subsystems for resource-constrained small satellites.

Comparison of an inflammation-based prognostic score (GPS) with performance status (ECOG-ps) in patients receiving palliative chemotherapy for gastroesophageal cancer.

Science.gov (United States)

Crumley, Andrew B C; Stuart, Robert C; McKernan, Margaret; McDonald, Alexander C; McMillan, Donald C

2008-08-01

The aim of the present study was to compare an inflammation-based prognostic score (Glasgow Prognostic Score, GPS) with performance status (ECOG-ps) in patients receiving platinum-based chemotherapy for palliation of gastroesophageal cancer. Sixty-five patients presenting with gastroesophageal carcinoma to the Royal Infirmary, Glasgow between January 1999 and December 2005 and who received palliative chemotherapy or chemo-radiotherapy were studied. ECOG-ps, C-reactive protein, and albumin were recorded at diagnosis. Patients with both an elevated C-reactive protein (>10 mg/L) and hypoalbuminemia (L) were allocated a GPS of 2. Patients in whom only one of these biochemical abnormalities was present were allocated a GPS of 1 and patients with a normal C-reactive protein and albumin were allocated a score of 0. Toxicity was recorded using the Common Toxicity Criteria. The minimum follow up was 14 months. During the follow-up period, 59 (91%) of the patients died. On univariate and multivariate survival analysis, only the GPS (hazard ratios 1.65, 95% CI 1.10-2.47, P GPS of 0, those patients with a GPS of 1 or 2 required more frequent chemotherapy dose reduction (P GPS, appears to be superior to the subjective assessment of performance status (ECOG-ps) in predicting the response to platinum-based chemotherapy in patients with advanced gastroesophageal cancer.

Performance enhancement for a GPS vector-tracking loop utilizing an adaptive iterated extended Kalman filter.

Science.gov (United States)

Chen, Xiyuan; Wang, Xiying; Xu, Yuan

2014-12-09

This paper deals with the problem of state estimation for the vector-tracking loop of a software-defined Global Positioning System (GPS) receiver. For a nonlinear system that has the model error and white Gaussian noise, a noise statistics estimator is used to estimate the model error, and based on this, a modified iterated extended Kalman filter (IEKF) named adaptive iterated Kalman filter (AIEKF) is proposed. A vector-tracking GPS receiver utilizing AIEKF is implemented to evaluate the performance of the proposed method. Through road tests, it is shown that the proposed method has an obvious accuracy advantage over the IEKF and Adaptive Extended Kalman filter (AEKF) in position determination. The results show that the proposed method is effective to reduce the root-mean-square error (RMSE) of position (including longitude, latitude and altitude). Comparing with EKF, the position RMSE values of AIEKF are reduced by about 45.1%, 40.9% and 54.6% in the east, north and up directions, respectively. Comparing with IEKF, the position RMSE values of AIEKF are reduced by about 25.7%, 19.3% and 35.7% in the east, north and up directions, respectively. Compared with AEKF, the position RMSE values of AIEKF are reduced by about 21.6%, 15.5% and 30.7% in the east, north and up directions, respectively.

An Integrated GPS/PDA/GIS Telegeoprocessing System for Traffic and Environment

Directory of Open Access Journals (Sweden)

Ana Luísa Ramos

2009-12-01

Full Text Available The development of sustainable urban transport networks is a present priority for world leaders, national governors and local authorities. The challenge is to increase mobility reducing the adverse impacts of transport. The potential of Intelligent Transportation Systems (ITS to provide solutions for the 21 st century sustainable urban transport system has already been demonstrated in several piecewise applications. An integrated framework that addresses the needs of municipal authorities, that integrates the data spread through different sources, that supports the intelligent traffic and environment operations, and that provides information to the citizens steering their involvement and commitment is of critical importance and can be the enabler towards the creation of more efficient, safety, and environmental-friendly transport networks that promote the citizens' quality of life. This work describes an integrated GPS (Global Positioning System / PDA (Personal Digital Assistant / GIS (Geographical Information System system which is part of the mentioned framework. The system includes prototypes for mobile urban traffic data acquisition, with a GPS -equipped vehicle, a PDA application and wireless communications, and for a geodatabase with a related Web application for urban traffic and environment. Their integrated operation is exemplified for a real urban transport system.

A RLS-SVM Aided Fusion Methodology for INS during GPS Outages.

Science.gov (United States)

Yao, Yiqing; Xu, Xiaosu

2017-02-24

In order to maintain a relatively high accuracy of navigation performance during global positioning system (GPS) outages, a novel robust least squares support vector machine (LS-SVM)-aided fusion methodology is explored to provide the pseudo-GPS position information for the inertial navigation system (INS). The relationship between the yaw, specific force, velocity, and the position increment is modeled. Rather than share the same weight in the traditional LS-SVM, the proposed algorithm allocates various weights for different data, which makes the system immune to the outliers. Field test data was collected to evaluate the proposed algorithm. The comparison results indicate that the proposed algorithm can effectively provide position corrections for standalone INS during the 300 s GPS outage, which outperforms the traditional LS-SVM method. Historical information is also involved to better represent the vehicle dynamics.

A RLS-SVM Aided Fusion Methodology for INS during GPS Outages

Directory of Open Access Journals (Sweden)

Yiqing Yao

2017-02-01

Full Text Available In order to maintain a relatively high accuracy of navigation performance during global positioning system (GPS outages, a novel robust least squares support vector machine (LS-SVM-aided fusion methodology is explored to provide the pseudo-GPS position information for the inertial navigation system (INS. The relationship between the yaw, specific force, velocity, and the position increment is modeled. Rather than share the same weight in the traditional LS-SVM, the proposed algorithm allocates various weights for different data, which makes the system immune to the outliers. Field test data was collected to evaluate the proposed algorithm. The comparison results indicate that the proposed algorithm can effectively provide position corrections for standalone INS during the 300 s GPS outage, which outperforms the traditional LS-SVM method. Historical information is also involved to better represent the vehicle dynamics.

High-precision coseismic displacement estimation with a single-frequency GPS receiver

Science.gov (United States)

Guo, Bofeng; Zhang, Xiaohong; Ren, Xiaodong; Li, Xingxing

2015-07-01

To improve the performance of Global Positioning System (GPS) in the earthquake/tsunami early warning and rapid response applications, minimizing the blind zone and increasing the stability and accuracy of both the rapid source and rupture inversion, the density of existing GPS networks must be increased in the areas at risk. For economic reasons, low-cost single-frequency receivers would be preferable to make the sparse dual-frequency GPS networks denser. When using single-frequency GPS receivers, the main problem that must be solved is the ionospheric delay, which is a critical factor when determining accurate coseismic displacements. In this study, we introduce a modified Satellite-specific Epoch-differenced Ionospheric Delay (MSEID) model to compensate for the effect of ionospheric error on single-frequency GPS receivers. In the MSEID model, the time-differenced ionospheric delays observed from a regional dual-frequency GPS network to a common satellite are fitted to a plane rather than part of a sphere, and the parameters of this plane are determined by using the coordinates of the stations. When the parameters are known, time-differenced ionospheric delays for a single-frequency GPS receiver could be derived from the observations of those dual-frequency receivers. Using these ionospheric delay corrections, coseismic displacements of a single-frequency GPS receiver can be accurately calculated based on time-differenced carrier-phase measurements in real time. The performance of the proposed approach is validated using 5 Hz GPS data collected during the 2012 Nicoya Peninsula Earthquake (Mw 7.6, 2012 September 5) in Costa Rica. This shows that the proposed approach improves the accuracy of the displacement of a single-frequency GPS station, and coseismic displacements with an accuracy of a few centimetres are achieved over a 10-min interval.

Development of GPS Receiver Kalman Filter Algorithms for Stationary, Low-Dynamics, and High-Dynamics Applications

Science.gov (United States)

2016-06-01

Filter Algorithms for Stationary, Low-Dynamics, and High-Dynamics Applications Executive Summary The Global Positioning system ( GPS ) is the primary...software that may need to be developed for performance prediction of current or future systems that incorporate GPS . The ultimate aim is to help inform...Defence Science and Technology Organisation in 1986. His major areas of work were adaptive tracking , sig- nal processing, and radar systems engineering

Mapping the Coastline Limits of the Mexican State Sinaloa Using GPS

Science.gov (United States)

Vazquez, G. E.

2007-12-01

This research work presents the delimitation of the coastline limits of Sinaloa (one of the richest states of northwestern Mexico). In order to achieve this big task, it was required to use GPS (Global Positioning System) together with leveling spirit measurements. Based on the appropriate selection of the cited measurement techniques, the objective was to map the Sinaloa's state coastline to have the cartography of approximate 1600 km of littoral. The GPS measurements were performed and referred with respect to a GPS network located across the state. This GPS network consists of at least one first-order-site at each of the sixteen counties that constitute the state, and three to four second-order-sites of the ten counties of the state surrounded by sea. The leveling spirit measurements were referred to local benchmarks pre-established by the Mexican agency SEMARNAT (SEcretaría Del Medio Ambiente y Recursos NATurales). Within the main specifications of the GPS measurements and equipment, we used geodetic-dual-frequency GPS receivers in kinematic mode for both base stations (first and second order sites of the GPS state network) and rover stations (points forming the state littoral) with 5-sec log-rate interval and 10 deg cut-off angle. The GPS data processing was performed using the commercial software Trimble Geomatics Office (TGO) with Double Differences (DD) in post-processing mode. To this point, the field measurements had been totally covered including the cartography (scale 1:1000) and this includes the specifications and appropriate labeling according to the Mexican norm NOM-146-SEMARNAT-2005.

Integration of GPS precise point positioning and MEMS-based INS using unscented particle filter.

Science.gov (United States)

Abd Rabbou, Mahmoud; El-Rabbany, Ahmed

2015-03-25

Integration of Global Positioning System (GPS) and Inertial Navigation System (INS) integrated system involves nonlinear motion state and measurement models. However, the extended Kalman filter (EKF) is commonly used as the estimation filter, which might lead to solution divergence. This is usually encountered during GPS outages, when low-cost micro-electro-mechanical sensors (MEMS) inertial sensors are used. To enhance the navigation system performance, alternatives to the standard EKF should be considered. Particle filtering (PF) is commonly considered as a nonlinear estimation technique to accommodate severe MEMS inertial sensor biases and noise behavior. However, the computation burden of PF limits its use. In this study, an improved version of PF, the unscented particle filter (UPF), is utilized, which combines the unscented Kalman filter (UKF) and PF for the integration of GPS precise point positioning and MEMS-based inertial systems. The proposed filter is examined and compared with traditional estimation filters, namely EKF, UKF and PF. Tightly coupled mechanization is adopted, which is developed in the raw GPS and INS measurement domain. Un-differenced ionosphere-free linear combinations of pseudorange and carrier-phase measurements are used for PPP. The performance of the UPF is analyzed using a real test scenario in downtown Kingston, Ontario. It is shown that the use of UPF reduces the number of samples needed to produce an accurate solution, in comparison with the traditional PF, which in turn reduces the processing time. In addition, UPF enhances the positioning accuracy by up to 15% during GPS outages, in comparison with EKF. However, all filters produce comparable results when the GPS measurement updates are available.

Design of Mobile Operation and Maintenance System Based on Power GIS and GPS

Directory of Open Access Journals (Sweden)

Jing TAO

2017-01-01

Full Text Available In order to solve the low efficiency of operation and maintenance and the problems of management coordination caused by the coexistence of off-line operation and maintenance and multi system coexistence in current power telecommunication operation and maintenance, this paper proposes a mobile operation and maintenance system based on power GIS and GPS location technology. The system is based on the C/S architecture, and the mobile operation and maintenance terminal is connected with the operation and maintenance management terminal through wireless and wired network. In addition to meeting basic business requirements, the system integrates power GIS functions to visually demonstrate communication resources, personnel, and failures. The staff can use the wireless mobile terminal which integrated GPS module for to operate and maintain, and can locate accurately in real time.

Transition of NOAA's GPS-Met Data Acquisition and Processing System to the Commercial Sector

Science.gov (United States)

Jackson, M. E.; Holub, K.; Callahan, W.; Blatt, S.

2014-12-01

In April of 2014, NOAA/OAR/ESRL Global Systems Division (GSD) and Trimble, in collaboration with Earth Networks, Inc. (ENI) signed a Cooperative Research and Development Agreement (CRADA) to transfer the existing NOAA GPS-Met Data Acquisition and Processing System (GPS-Met DAPS) technology to a commercial Trimble/ENI partnership. NOAA's GPS-Met DAPS is currently operated in a pseudo-operational mode but has proven highly reliable and running at over 95% uptime. The DAPS uses the GAMIT software to ingest dual frequency carrier phase GPS/GNSS observations and ancillary information such as real-time satellite orbits to estimate the zenith-scaled tropospheric (ZTD) signal delays and, where surface MET data are available, retrieve integrated precipitable water vapor (PWV). The NOAA data and products are made available to end users in near real-time. The Trimble/ENI partnership will use the Trimble Pivot™ software with the Atmosphere App to calculate zenith tropospheric (ZTD), tropospheric slant delay, and integrated precipitable water vapor (PWV). Evaluation of the Trimble software is underway starting with a comparison of ZTD and PWV values determined from GPS stations located near NOAA Radiosonde Observation (Upper-Air Observation) launch sites. A success metric was established that requires Trimble's PWV estimates to match ESRL/GSD's to within 1.5 mm 95% of the time, which corresponds to a ZTD uncertainty of less than 10 mm 95% of the time. Initial results indicate that Trimble/ENI data meet and exceed the ZTD metric, but for some stations PWV estimates are out of specification. These discrepancies are primarily due to how offsets between MET and GPS stations are handled and are easily resolved. Additional test networks are proposed that include low terrain/high moisture variability stations, high terrain/low moisture variability stations, as well as high terrain/high moisture variability stations. We will present results from further testing along with a timeline

Ground-Based Global Positioning System (GPS) Meteorology Integrated Precipitable Water Vapor (IPW)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Ground-Based Global Positioning System (GPS) Meteorology Integrated Precipitable Water Vapor (IPW) data set measures atmospheric water vapor using ground-based...

Transition of NOAA's GPS-Met Data Acquisition and Processing System to the Commercial Sector: Inital Results

Science.gov (United States)

Jackson, Michael; Blatt, Stephan; Holub, Kirk

2015-04-01

In April of 2014, NOAA/OAR/ESRL Global Systems Division (GSD) and Trimble, in collaboration with Earth Networks, Inc. (ENI) signed a Cooperative Research and Development Agreement (CRADA) to transfer the existing NOAA GPS-Met Data Acquisition and Processing System (GPS-Met DAPS) technology to a commercial Trimble/ENI partnership. NOAA's GPS-Met DAPS is currently operated in a pseudo-operational mode but has proven highly reliable and running at over 95% uptime. The DAPS uses the GAMIT software to ingest dual frequency carrier phase GPS/GNSS observations and ancillary information such as real-time satellite orbits to estimate the zenith-scaled tropospheric (ZTD) signal delays and, where surface MET data are available, retrieve integrated precipitable water vapor (PWV). The NOAA data and products are made available to end users in near real-time. The Trimble/ENI partnership will use the Trimble Pivot™ software with the Atmosphere App to calculate zenith tropospheric (ZTD), tropospheric slant delay, and integrated precipitable water vapor (PWV). Evaluation of the Trimble software is underway starting with a comparison of ZTD and PWV values determined from four sub networks of GPS stations located 1. near NOAA Radiosonde Observation (Upper-Air Observation) launch sites; 2. Stations with low terrain/high moisture variability (Gulf Coast); 3. Stations with high terrain/low moisture variability (Southern California); and 4. Stations with high terrain/high moisture variability (high terrain variability elev. > 1000m). For each network GSD and T/ENI run the same stations for 30 days, compare results, and perform an evaluation of the long-term solution accuracy, precision and reliability. Metrics for success include T/ENI PWV estimates within 1.5 mm of ESRL/GSD's estimates 95% of the time (ZTD uncertainty of less than 10 mm 95% of the time). The threshold for allowable variations in ZTD between NOAA GPS-Met and T/ENI processing are 10mm. The CRADA 1&2 Trimble processing

A GPS Phase-Locked Loop Performance Metric Based on the Phase Discriminator Output.

Science.gov (United States)

Stevanovic, Stefan; Pervan, Boris

2018-01-19

We propose a novel GPS phase-lock loop (PLL) performance metric based on the standard deviation of tracking error (defined as the discriminator's estimate of the true phase error), and explain its advantages over the popular phase jitter metric using theory, numerical simulation, and experimental results. We derive an augmented GPS phase-lock loop (PLL) linear model, which includes the effect of coherent averaging, to be used in conjunction with this proposed metric. The augmented linear model allows more accurate calculation of tracking error standard deviation in the presence of additive white Gaussian noise (AWGN) as compared to traditional linear models. The standard deviation of tracking error, with a threshold corresponding to half of the arctangent discriminator pull-in region, is shown to be a more reliable/robust measure of PLL performance under interference conditions than the phase jitter metric. In addition, the augmented linear model is shown to be valid up until this threshold, which facilitates efficient performance prediction, so that time-consuming direct simulations and costly experimental testing can be reserved for PLL designs that are much more likely to be successful. The effect of varying receiver reference oscillator quality on the tracking error metric is also considered.

UNITED STATES DEPARTMENT OF TRANSPORTATION GLOBAL POSITIONING SYSTEM (GPS) ADJACENT BAND COMPATIBILITY ASSESSMENT

Science.gov (United States)

2018-04-01

The goal of the U.S. Department of Transportation (DOT) Global Positioning System (GPS) Adjacent Band Compatibility Assessment is to evaluate the maximum transmitted power levels of adjacent band radiofrequency (RF) systems that can be tolerated by G...

Individuals' preferences for GPs Choice analysis from the establishment of a list patient system in Norway

OpenAIRE

Lurås, Hilde

2009-01-01

The purpose of this paper is to gain more knowledge concerning individuals’ preferences for alternative GPs within a municipality. We have data on the population’s first, second and third choice of GPs. The data stem from the entry form the inhabitant filled in as a result of the implementation of a list patient system in general practice in Norway. To assess the potential demand for GPs3 or individuals’ request for a position on a certain GP’s list, we formulate and estimate a structural dem...

A System to Produce Precise Global GPS Network Solutions for all Geodetic GPS Stations in the World

Science.gov (United States)

Blewitt, G.; Kreemer, C. W.

2010-12-01

We have developed an end-to-end system that automatically seeks and routinely retrieves geodetic GPS data from ~5000 stations (currently) around the globe, reduces the data into unique, daily global network solutions, and produces high precision time series for station coordinates ready for time-series analysis, geophysical modeling and interpretation. Moreover, “carrier range” data are produced for all stations, enabling epoch-by-epoch tracking of individual station motions by precise point positioning for investigation of sub-daily processes, such as post-seismic after-slip and ocean tidal loading. Solutions are computed in a global reference frame aligned to ITRF, and optionally in user-specified continental-scale reference frames that can filter out common-mode signals to enhance regional strain anomalies. We describe the elements of this system, the underlying signal processing theory, the products, operational statistics, and scientific applications of our system. The system is fundamentally based on precise point positioning using JPL's GIPSY OASIS II software, coupled with ambiguity resolution and a global network adjustment of ~300,000 parameters per day using our newly developed Ambizap3 software. The system is designed to easily and efficiently absorb stations that deliver data very late, by recycling prior computations in the network adjustment, such that the resulting network solution is identical to starting from scratch. Thus, it becomes possible to trawl continuously the Internet for late arriving data, or for newly discovered data, and seamlessly update all GPS station time series using the new information content. As new stations are added to the processing archive, automated e-mail requests are made to H.-G. Scherneck's server at Chalmers University to compute ocean loading coefficients used by the station motion model. Rinex file headers are parsed and compared with alias tables in order to infer the correct receiver type and antenna

GPS Test Facility

Data.gov (United States)

Federal Laboratory Consortium — The Global Positioning System (GPS) Test Facility Instrumentation Suite (GPSIS) provides great flexibility in testing receivers by providing operational control of...

Development of GPS survey data management protocols/policy.

Science.gov (United States)

2010-08-01

This project developed a statewide policy and criteria for collecting, analyzing, and managing global position system (GPS) survey data. The research project determined the needs of the Department in adopting the GPS real time kinetic (GPS RTK) stake...

PDOP values for simulated GPS/Galileo positioning

DEFF Research Database (Denmark)

Cederholm, Jens Peter

2005-01-01

The paper illustrates satellite coverage and PDOP values for a simulated combined GPS/Galileo system. The designed GPS satellite constellation and the planned Galileo satellite constellation are presented. The combined system is simulated and the number of visible satellites and PDOP values...

Real-Time Single-Frequency GPS/MEMS-IMU Attitude Determination of Lightweight UAVs

Science.gov (United States)

Eling, Christian; Klingbeil, Lasse; Kuhlmann, Heiner

2015-01-01

In this paper, a newly-developed direct georeferencing system for the guidance, navigation and control of lightweight unmanned aerial vehicles (UAVs), having a weight limit of 5 kg and a size limit of 1.5 m, and for UAV-based surveying and remote sensing applications is presented. The system is intended to provide highly accurate positions and attitudes (better than 5 cm and 0.5∘) in real time, using lightweight components. The main focus of this paper is on the attitude determination with the system. This attitude determination is based on an onboard single-frequency GPS baseline, MEMS (micro-electro-mechanical systems) inertial sensor readings, magnetic field observations and a 3D position measurement. All of this information is integrated in a sixteen-state error space Kalman filter. Special attention in the algorithm development is paid to the carrier phase ambiguity resolution of the single-frequency GPS baseline observations. We aim at a reliable and instantaneous ambiguity resolution, since the system is used in urban areas, where frequent losses of the GPS signal lock occur and the GPS measurement conditions are challenging. Flight tests and a comparison to a navigation-grade inertial navigation system illustrate the performance of the developed system in dynamic situations. Evaluations show that the accuracies of the system are 0.05∘ for the roll and the pitch angle and 0.2∘ for the yaw angle. The ambiguities of the single-frequency GPS baseline can be resolved instantaneously in more than 90% of the cases. PMID:26501281

Transportation mode recognition using GPS and accelerometer data

NARCIS (Netherlands)

Feng, T.; Timmermans, H.J.P.

2013-01-01

Potential advantages of global positioning systems (GPS) in collecting travel behavior data have been discussed in several publications and evidenced in many recent studies. Most applications depend on GPS information only. However, transportation mode detection that relies only on GPS information

Design and testing of a GPS/GSM collar prototype to combat cattle rustling

Directory of Open Access Journals (Sweden)

Francesco M. Tangorra

2013-10-01

Full Text Available Rustling is an age-old practice that was widespread in Italy until the first half of the 20th century. Today, incidents of cattle rustling are again being reported. However, the problem is not only found in Italy. It is also becoming a plague for ranchers in the US and is still rampant in East Africa. In Italy, the cattle rustling phenomena have usually been limited through the direct control of the herdsmen. Global positioning system (GPS and geographic information system (GIS combined technologies are increasingly applied for tracking and monitoring livestock with greater spatial and temporal resolution. However, so far, no case studies of the use of GPS technology to combat cattle rustling have been reported in the literature. The aim of this research was to develop a GPS/GSM (global system for mobile communication collar, using commercial hardware and implementing a specific software [ARVAshepherd 1.0; ARVAtec Srl, Rescaldina (MI, Italy] to track animals’ movements outside their grazing area and to signal when animals are straying outside virtual perimeters. A phase I study was conducted from January to June 2011 to build the GPS/GSM collar and to assess its performances in terms of GPS accuracy and precision, while a phase II study was conducted in July 2011 to test the GPS collar under real-life operating conditions. The static GPS positioning error achieved a circular error probable (50% and horizontal 95% accuracy of 1.462 m and 4.501 m, respectively. This is comparable with values obtained by other authors in static tests of a commercial GPS collar for grazing studies. In field tests, the system was able to identify the incorrect position of the cattle and the warning messages were sent promptly to the farmer, continuing until the animals had been repositioned inside the fence, thus highlighting the potential of the GPS/GSM collar as an anti-theft system.

Travel patterns during pregnancy: comparison between Global Positioning System (GPS) tracking and questionnaire data.

Science.gov (United States)

Wu, Jun; Jiang, Chengsheng; Jaimes, Guillermo; Bartell, Scott; Dang, Andy; Baker, Dean; Delfino, Ralph J

2013-10-09

Maternal exposures to traffic-related air pollution have been associated with adverse pregnancy outcomes. Exposures to traffic-related air pollutants are strongly influenced by time spent near traffic. However, little is known about women's travel activities during pregnancy and whether questionnaire-based data can provide reliable information on travel patterns during pregnancy. Examine women's in-vehicle travel behavior during pregnancy and examine the difference in travel data collected by questionnaire and global positioning system (GPS) and their potential for exposure error. We measured work-related travel patterns in 56 pregnant women using a questionnaire and one-week GPS tracking three times during pregnancy (30 weeks of gestation). We compared self-reported activities with GPS-derived trip distance and duration, and examined potentially influential factors that may contribute to differences. We also described in-vehicle travel behavior by pregnancy periods and influences of demographic and personal factors on daily travel times. Finally, we estimated personal exposure to particle-bound polycyclic aromatic hydrocarbon (PB-PAH) and examined the magnitude of exposure misclassification using self-reported vs. GPS travel data. Subjects overestimated both trip duration and trip distance compared to the GPS data. We observed moderately high correlations between self-reported and GPS-recorded travel distance (home to work trips: r = 0.88; work to home trips: r = 0.80). Better agreement was observed between the GPS and the self-reported travel time for home to work trips (r = 0.77) than work to home trips (r = 0.64). The subjects on average spent 69 and 93 minutes traveling in vehicles daily based on the GPS and self-reported data, respectively. Longer daily travel time was observed among participants in early pregnancy, and during certain pregnancy periods in women with higher education attainment, higher income, and no children. When comparing

A generalized development model for testing GPS user equipment

Science.gov (United States)

Hemesath, N.

1978-01-01

The generalized development model (GDM) program, which was intended to establish how well GPS user equipment can perform under a combination of jamming and dynamics, is described. The systems design and the characteristics of the GDM are discussed. The performance aspects of the GDM are listed and the application of the GDM to civil aviation is examined.

The impact of a diagnostic decision support system on the consultation: perceptions of GPs and patients.

Science.gov (United States)

Porat, Talya; Delaney, Brendan; Kostopoulou, Olga

2017-06-02

Clinical decision support systems (DSS) aimed at supporting diagnosis are not widely used. This is mainly due to usability issues and lack of integration into clinical work and the electronic health record (EHR). In this study we examined the usability and acceptability of a diagnostic DSS prototype integrated with the EHR and in comparison with the EHR alone. Thirty-four General Practitioners (GPs) consulted with 6 standardised patients (SPs) using only their EHR system (baseline session); on another day, they consulted with 6 different but matched for difficulty SPs, using the EHR with the integrated DSS prototype (DSS session). GPs were interviewed twice (at the end of each session), and completed the Post-Study System Usability Questionnaire at the end of the DSS session. The SPs completed the Consultation Satisfaction Questionnaire after each consultation. The majority of GPs (74%) found the DSS useful: it helped them consider more diagnoses and ask more targeted questions. They considered three user interface features to be the most useful: (1) integration with the EHR; (2) suggested diagnoses to consider at the start of the consultation and; (3) the checklist of symptoms and signs in relation to each suggested diagnosis. There were also criticisms: half of the GPs felt that the DSS changed their consultation style, by requiring them to code symptoms and signs while interacting with the patient. SPs sometimes commented that GPs were looking at their computer more than at them; this comment was made more often in the DSS session (15%) than in the baseline session (3%). Nevertheless, SP ratings on the satisfaction questionnaire did not differ between the two sessions. To use the DSS effectively, GPs would need to adapt their consultation style, so that they code more information during rather than at the end of the consultation. This presents a potential barrier to adoption. Training GPs to use the system in a patient-centred way, as well as improvement of the

Allocation of time under different payment systems by GPs in Europe.

NARCIS (Netherlands)

Boerma, W.; Groenewegen, P.; Spreeuwenberg, P.

2003-01-01

Background: Payment of GPs is relevant from two points of view: fair payment and effects on the quality of care. Fair pay is especially important in capitation systems (does the amount correctly reflect the invested work). Secondly, payment affects the allocation of time, and thus indirect the

GPS operations at Olkiluoto in 2011

International Nuclear Information System (INIS)

Koivula, H.; Kallio, U.; Nyberg, S.; Jokela, J.; Poutanen, M.

2012-06-01

The Finnish Geodetic Institute has studied crustal deformations at Olkiluoto, Kivetty and Romuvaara in co-operation with Posiva Oy since 1995. At Olkiluoto a total of 32 GPS campaigns have been carried out at inner network since 1995 and 17 campaigns at outer network since 2003. Kivetty and Romuvaara were not measured in 2011. In the Olkiluoto inner network 80 percent of the estimated change rates are smaller than 0.10 mm/a. One third of the change rates are statistically significant. They are mainly related to the Olkiluoto permanent station (GPS1) and to the pillars GPS6 and GPS13. The change rates related to GPS6 are not realistic due to the site-specific changes affecting the time series. The maximum change rate (-0.20 mm/a ± 0.05 mm/a) is related to GPS13. The time series of GPS13 is half the length of other pillars and therefore, the change rates are more uncertain. In the Olkiluoto outer network the maximum and statistically significant change rate is between GPS1-GPS11 (0.39 mm/a ± 0.06 mm/a). Pillar GPS12 was not observed this year. The change rates of baselines GPS1-GPS14 and GPS1-GPS15 are first time statistically significant. The change rates indicate a small movement of the GPS1 pillar. The baseline GPS1-GPS11 crosses an old fracture zone locating in the direction of the Eurajoensalmi, which might be a reason for the deformation. On the other hand, the Onkalo excavations in the vicinity of the Olkiluoto permanent station (GPS1) may cause some movement. Electronic distance measurements have been performed at Olkiluoto at the baseline GPS7-GPS8 using the Mekometer since 2002. The measurements have been carried out simultaneously with GPS campaigns. Based on 19 measurements in 10 years, the trends of the two time series seems to be similar. Due to unmodelled or dismodelled geometrical offsets and the scale difference between GPS measurements and EDM there is about 0.3 mm difference between distances GPS7-GPS8 derived from GPS measurements and EDM. It is

GPS operations at Olkiluoto in 2011

Energy Technology Data Exchange (ETDEWEB)

Koivula, H.; Kallio, U.; Nyberg, S.; Jokela, J.; Poutanen, M. [Finnish Geodetic Institute, Masala (Finland)

2012-06-15

The Finnish Geodetic Institute has studied crustal deformations at Olkiluoto, Kivetty and Romuvaara in co-operation with Posiva Oy since 1995. At Olkiluoto a total of 32 GPS campaigns have been carried out at inner network since 1995 and 17 campaigns at outer network since 2003. Kivetty and Romuvaara were not measured in 2011. In the Olkiluoto inner network 80 percent of the estimated change rates are smaller than 0.10 mm/a. One third of the change rates are statistically significant. They are mainly related to the Olkiluoto permanent station (GPS1) and to the pillars GPS6 and GPS13. The change rates related to GPS6 are not realistic due to the site-specific changes affecting the time series. The maximum change rate (-0.20 mm/a {+-} 0.05 mm/a) is related to GPS13. The time series of GPS13 is half the length of other pillars and therefore, the change rates are more uncertain. In the Olkiluoto outer network the maximum and statistically significant change rate is between GPS1-GPS11 (0.39 mm/a {+-} 0.06 mm/a). Pillar GPS12 was not observed this year. The change rates of baselines GPS1-GPS14 and GPS1-GPS15 are first time statistically significant. The change rates indicate a small movement of the GPS1 pillar. The baseline GPS1-GPS11 crosses an old fracture zone locating in the direction of the Eurajoensalmi, which might be a reason for the deformation. On the other hand, the Onkalo excavations in the vicinity of the Olkiluoto permanent station (GPS1) may cause some movement. Electronic distance measurements have been performed at Olkiluoto at the baseline GPS7-GPS8 using the Mekometer since 2002. The measurements have been carried out simultaneously with GPS campaigns. Based on 19 measurements in 10 years, the trends of the two time series seems to be similar. Due to unmodelled or dismodelled geometrical offsets and the scale difference between GPS measurements and EDM there is about 0.3 mm difference between distances GPS7-GPS8 derived from GPS measurements and EDM

Comparison of a GPS needle-tracking system, multiplanar imaging and 2D imaging for real-time ultrasound-guided epidural anaesthesia: A randomized, comparative, observer-blinded study on phantoms.

Science.gov (United States)

Menacé, Cécilia; Choquet, Olivier; Abbal, Bertrand; Bringuier, Sophie; Capdevila, Xavier

2017-04-01

The real-time ultrasound-guided paramedian sagittal oblique approach for neuraxial blockade is technically demanding. Innovative technologies have been developed to improve nerve identification and the accuracy of needle placement. The aim of this study was to evaluate three types of ultrasound scans during ultrasound-guided epidural lumbar punctures in a spine phantom. Eleven sets of 20 ultrasound-guided epidural punctures were performed with 2D, GPS, and multiplanar ultrasound machines (660 punctures) on a spine phantom using an in-plane approach. For all punctures, execution time, number of attempts, bone contacts, and needle redirections were noted by an independent physician. Operator comfort and visibility of the needle (tip and shaft) were measured using a numerical scale. The use of GPS significantly decreased the number of punctures, needle repositionings, and bone contacts. Comfort of the physician was also significantly improved with the GPS system compared with the 2D and multiplanar systems. With the multiplanar system, the procedure was not facilitated and execution time was longer compared with 2D imaging after Bonferroni correction but interaction between the type of ultrasound system and mean execution time was not significant in a linear mixed model. There were no significant differences regarding needle tip and shaft visibility between the systems. Multiplanar and GPS needle-tracking systems do not reduce execution time compared with 2D imaging using a real-time ultrasound-guided paramedian sagittal oblique approach in spine phantoms. The GPS needle-tracking system can improve performance in terms of operator comfort, the number of attempts, needle redirections and bone contacts. Copyright © 2016 Société française d'anesthésie et de réanimation (Sfar). Published by Elsevier Masson SAS. All rights reserved.

Performances of different global positioning system devices for time-location tracking in air pollution epidemiological studies.

Science.gov (United States)

Wu, Jun; Jiang, Chengsheng; Liu, Zhen; Houston, Douglas; Jaimes, Guillermo; McConnell, Rob

2010-11-23

People's time-location patterns are important in air pollution exposure assessment because pollution levels may vary considerably by location. A growing number of studies are using global positioning systems (GPS) to track people's time-location patterns. Many portable GPS units that archive location are commercially available at a cost that makes their use feasible for epidemiological studies. We evaluated the performance of five portable GPS data loggers and two GPS cell phones by examining positional accuracy in typical locations (indoor, outdoor, in-vehicle) and factors that influence satellite reception (building material, building type), acquisition time (cold and warm start), battery life, and adequacy of memory for data storage. We examined stationary locations (eg, indoor, outdoor) and mobile environments (eg, walking, traveling by vehicle or bus) and compared GPS locations to highly-resolved US Geological Survey (USGS) and Digital Orthophoto Quarter Quadrangle (DOQQ) maps. The battery life of our tested instruments ranged from acquisition of location time after startup ranged from a few seconds to >20 minutes and varied significantly by building structure type and by cold or warm start. No GPS device was found to have consistently superior performance with regard to spatial accuracy and signal loss. At fixed outdoor locations, 65%-95% of GPS points fell within 20-m of the corresponding DOQQ locations for all the devices. At fixed indoor locations, 50%-80% of GPS points fell within 20-m of the corresponding DOQQ locations for all the devices except one. Most of the GPS devices performed well during commuting on a freeway, with >80% of points within 10-m of the DOQQ route, but the performance was significantly impacted by surrounding structures on surface streets in highly urbanized areas. All the tested GPS devices had limitations, but we identified several devices which showed promising performance for tracking subjects' time location patterns in

GPS Composite Clock Analysis

OpenAIRE

Wright, James R.

2008-01-01

The GPS composite clock defines GPS time, the timescale used today in GPS operations. GPS time is illuminated by examination of its role in the complete estimation and control problem relative to UTC/TAI. The phase of each GPS clock is unobservable from GPS pseudorange measurements, and the mean phase of the GPS clock ensemble (GPS time) is unobservable. A new and useful observability definition is presented, together with new observability theorems, to demonstrate explicitly that GPS time is...

Penerapan Teknologi GPS Tracker Untuk Identifikasi Kondisi Traffik Jalan Raya

Directory of Open Access Journals (Sweden)

IM. O. Widyantara

2015-06-01

Full Text Available Real time tracking system technology has been made possible by integrating three technologies, namely global positioning system (GPS, database technologies such as geographic information system (GIS and mobile telecommunications technologies such as general packet radio service (GPRS. This paper has proposed a vehicle tracking mechanism based on GPS tracker to build a real-time traffic information system. A GPS server is built to process data of position and speed of the vehicle for further processed into vehicle traffic information. The Server and GPS tracker is designed to communicate using GPRS services in real time. Furthermore, the server processes the data from the GPS tracker into traffic information such as traffic jam, dense, medium and smoothly. Test results showed that the GPS server is able to visualize the real position of the vehicle and is able to decide the category of traffic information in real time.

GPS User Devices Parameter Control Methods

OpenAIRE

Klūga, A; Kuļikovs, M; Beļinska, V; Zeļenkovs, A

2007-01-01

In our day’s wide assortment of GPS user devices is manufacture. How to verify that parameters of the real device corresponds to parameters that manufacture shows. How to verify that parameters have not been changed during the operation time. The last one is very important for aviation GPS systems, which must be verified before the flight, but the values of parameter in time of repair works. This work analyses GPS user devices parameters control methods.

Accuracy, intra- and inter-unit reliability, and comparison between GPS and UWB-based position-tracking systems used for time-motion analyses in soccer.

Science.gov (United States)

Bastida Castillo, Alejandro; Gómez Carmona, Carlos D; De la Cruz Sánchez, Ernesto; Pino Ortega, José

2018-05-01

There is interest in the accuracy and inter-unit reliability of position-tracking systems to monitor players. Research into this technology, although relatively recent, has grown exponentially in the last years, and it is difficult to find professional team sport that does not use Global Positioning System (GPS) technology at least. The aim of this study is to know the accuracy of both GPS-based and Ultra Wide Band (UWB)-based systems on a soccer field and their inter- and intra-unit reliability. A secondary aim is to compare them for practical applications in sport science. Following institutional ethical approval and familiarization, 10 healthy and well-trained former soccer players (20 ± 1.6 years, 1.76 ± 0.08 cm, and 69.5 ± 9.8 kg) performed three course tests: (i) linear course, (ii) circular course, and (iii) a zig-zag course, all using UWB and GPS technologies. The average speed and distance covered were compared with timing gates and the real distance as references. The UWB technology showed better accuracy (bias: 0.57-5.85%), test-retest reliability (%TEM: 1.19), and inter-unit reliability (bias: 0.18) in determining distance covered than the GPS technology (bias: 0.69-6.05%; %TEM: 1.47; bias: 0.25) overall. Also, UWB showed better results (bias: 0.09; ICC: 0.979; bias: 0.01) for mean velocity measurement than GPS (bias: 0.18; ICC: 0.951; bias: 0.03).

77 FR 70421 - GPS Satellite Simulator Control Working Group Meeting

Science.gov (United States)

2012-11-26

... DEPARTMENT OF DEFENSE Department of the Air Force GPS Satellite Simulator Control Working Group Meeting AGENCY: Space and Missile Systems Center, Global Positioning Systems (GPS) Directorate, Department of the Air Force, DoD. ACTION: Meeting Notice. SUMMARY: This meeting notice is to inform GPS...

Systemic insulin sensitivity is regulated by GPS2 inhibition of AKT ubiquitination and activation in adipose tissue.

Science.gov (United States)

Cederquist, Carly T; Lentucci, Claudia; Martinez-Calejman, Camila; Hayashi, Vanessa; Orofino, Joseph; Guertin, David; Fried, Susan K; Lee, Mi-Jeong; Cardamone, M Dafne; Perissi, Valentina

2017-01-01

Insulin signaling plays a unique role in the regulation of energy homeostasis and the impairment of insulin action is associated with altered lipid metabolism, obesity, and Type 2 Diabetes. The main aim of this study was to provide further insight into the regulatory mechanisms governing the insulin signaling pathway by investigating the role of non-proteolytic ubiquitination in insulin-mediated activation of AKT. The molecular mechanism of AKT regulation through ubiquitination is first dissected in vitro in 3T3-L1 preadipocytes and then validated in vivo using mice with adipo-specific deletion of GPS2, an endogenous inhibitor of Ubc13 activity (GPS2-AKO mice). Our results indicate that K63 ubiquitination is a critical component of AKT activation in the insulin signaling pathway and that counter-regulation of this step is provided by GPS2 preventing AKT ubiquitination through inhibition of Ubc13 enzymatic activity. Removal of this negative checkpoint, through GPS2 downregulation or genetic deletion, results in sustained activation of insulin signaling both in vitro and in vivo . As a result, the balance between lipid accumulation and utilization is shifted toward storage in the adipose tissue and GPS2-AKO mice become obese under normal laboratory chow diet. However, the adipose tissue of GPS2-AKO mice is not inflamed, the levels of circulating adiponectin are elevated, and systemic insulin sensitivity is overall improved. Our findings characterize a novel layer of regulation of the insulin signaling pathway based on non-proteolytic ubiquitination of AKT and define GPS2 as a previously unrecognized component of the insulin signaling cascade. In accordance with this role, we have shown that GPS2 presence in adipocytes modulates systemic metabolism by restricting the activation of insulin signaling during the fasted state, whereas in absence of GPS2, the adipose tissue is more efficient at lipid storage, and obesity becomes uncoupled from inflammation and insulin

Performance Analysis of Low-Cost Single-Frequency GPS Receivers in Hydrographic Surveying

Science.gov (United States)

Elsobeiey, M.

2017-10-01

The International Hydrographic Organization (IHO) has issued standards that provide the minimum requirements for different types of hydrographic surveys execution to collect data to be used to compile navigational charts. Such standards are usually updated from time to time to reflect new survey techniques and practices and must be achieved to assure both surface navigation safety and marine environment protection. Hydrographic surveys can be classified to four orders namely, special order, order 1a, order 1b, and order 2. The order of hydrographic surveys to use should be determined in accordance with the importance to the safety of navigation in the surveyed area. Typically, geodetic-grade dual-frequency GPS receivers are utilized for position determination during data collection in hydrographic surveys. However, with the evolution of high-sensitivity low-cost single-frequency receivers, it is very important to evaluate the performance of such receivers. This paper investigates the performance of low-cost single-frequency GPS receivers in hydrographic surveying applications. The main objective is to examine whether low-cost single-frequency receivers fulfil the IHO standards for hydrographic surveys. It is shown that the low-cost single-frequency receivers meet the IHO horizontal accuracy for all hydrographic surveys orders at any depth. However, the single-frequency receivers meet only order 2 requirements for vertical accuracy at depth more than or equal 100 m.

The Statistics of GPS

National Research Council Canada - National Science Library

Matsakis, Demetrios

2007-01-01

The Global Positioning System (GPS) is an extremely effective satellite-based system that broadcasts sufficient information for a user to determine time and position from any location on or near the Earth...

Systemic insulin sensitivity is regulated by GPS2 inhibition of AKT ubiquitination and activation in adipose tissue

Directory of Open Access Journals (Sweden)

Carly T. Cederquist

2017-01-01

Conclusions: Our findings characterize a novel layer of regulation of the insulin signaling pathway based on non-proteolytic ubiquitination of AKT and define GPS2 as a previously unrecognized component of the insulin signaling cascade. In accordance with this role, we have shown that GPS2 presence in adipocytes modulates systemic metabolism by restricting the activation of insulin signaling during the fasted state, whereas in absence of GPS2, the adipose tissue is more efficient at lipid storage, and obesity becomes uncoupled from inflammation and insulin resistance.

COSMIC Payload in NCAR-NASPO GPS Satellite System for Severe Weather Prediction

Science.gov (United States)

Lai-Chen, C.

Severe weather, such as cyclones, heavy rainfall, outburst of cold air, etc., results in great disaster all the world. It is the mission for the scientists to design a warning system, to predict the severe weather systems and to reduce the damage of the society. In Taiwan, National Satellite Project Office (NSPO) initiated ROCSAT-3 program at 1997. She scheduled the Phase I conceptual design to determine the mission for observation weather system. Cooperating with National Center of Atmospheric Research (NCAR), NSPO involved an international cooperation research and operation program to build a 32 GPS satellites system. NCAR will offer 24 GPS satellites. The total expanse will be US 100 millions. NSPO also provide US 80 millions for launching and system engineering operation. And NCAR will be responsible for Payload Control Center and Fiducial Network. The cooperative program contract has been signed by Taiwan National Science Council, Taipei Economic Cultural Office of United States and American Institute in Taiwan. One of the payload is COSMIC, Constellation Observation System for Meteorology, Ionosphere and Climate. It is a GPS meteorology instrument system. The system will observe the weather information, e. g. electron density profiles, horizontal and vertical TEC and CFT scintillation and communication outage maps. The mission is to obtain the weather data such as vertical temperature profiles, water vapor distribution and pressure distribution over the world for global weather forecasting, especially during the severe weather period. The COSMIC Conference held on November, 1998. The export license was also issued by Department of Commerce of Unites States at November, 1998. Recently, NSPO begun to train their scientists to investigate the system. Scientists simulate the observation data to combine the existing routine satellite infrared cloud maps, radar echo and synoptic weather analysis for severe weather forecasting. It is hopeful to provide more accurate

A Nonlinear Observer for Integration of GPS and Inertial Navigation Systems

Directory of Open Access Journals (Sweden)

Bjørnar Vik

2000-10-01

Full Text Available GPS and INS have complementary properties and they are therefore well suited for integration. The integrated solution offers better long term accuracy than a stand-alone INS, and better integrity, availability and continuity than a stand-alone GPS receiver, making it suitable for demanding applications. The integrated filter is nonlinear both in state and measurements, and the extended Kalman-filter has been used with good results, but it has not been proven globally stable, and it is also computationally intensive, especially within a direct integration architecture. In this work a nonlinear observer suitable for direct integration is presented. Global exponent ial stability of the origin of the combined attitude and velocity error systems is proven along with robust stability in the presence of noise and unmodelled dynamics.

Comparison of global positioning system (GPS) tracking and parent-report diaries to characterize children's time-location patterns.

Science.gov (United States)

Elgethun, Kai; Yost, Michael G; Fitzpatrick, Cole T E; Nyerges, Timothy L; Fenske, Richard A

2007-03-01

Respondent error, low resolution, and study participant burden are known limitations of diary timelines used in exposure studies such as the National Human Exposure Assessment Survey (NHEXAS). Recent advances in global positioning system (GPS) technology have produced tracking devices sufficiently portable, functional and affordable to utilize in exposure assessment science. In this study, a differentially corrected GPS (dGPS) tracking device was compared to the NHEXAS diary timeline. The study also explored how GPS can be used to evaluate and improve such diary timelines by determining which location categories and which respondents are least likely to record "correct" time-location responses. A total of 31 children ages 3-5 years old wore a dGPS device for all waking hours on a weekend day while their parents completed the NHEXAS diary timeline to document the child's time-location pattern. Parents misclassified child time-location approximately 48% of the time using the NHEXAS timeline in comparison to dGPS. Overall concordance between methods was marginal (kappa=0.33-0.35). The dGPS device found that on average, children spent 76% of the 24-h study period in the home. The diary underestimated time the child spent in the home by 17%, while overestimating time spent inside other locations, outside at home, outside in other locations, and time spent in transit. Diary data for time spent outside at home and time in transit had the lowest response concordance with dGPS. The diaries of stay-at-home mothers and mothers working unskilled labor jobs had lower concordance with dGPS than did those of the other participants. The ability of dGPS tracking to collect continuous rather than categorical (ordinal) data was also demonstrated. It is concluded that automated GPS tracking measurements can improve the quality and collection efficiency of time-location data in exposure assessment studies, albeit for small cohorts.

Tractor-mounted, GPS-based spot fumigation system manages Prunus replant disease

Science.gov (United States)

Our research goal was to use recent advances in global positioning system (GPS) and computer technology to apply just the right amount of fumigant where it is most needed (i.e., in a small target treatment zone in and around each tree replanting site) to control Prunus replant disease (PRD). We deve...

Briefing highlights space weather risks to GPS

Science.gov (United States)

Tretkoff, Ernie

2011-07-01

Solar storms, which are expected to increase as the Sun nears the most active phase of the solar cycle, can disrupt a variety of technologies on which society relies. Speakers at a 22 June briefing on Capitol Hill in Washington, D. C., focused on how space weather can affect the Global Positioning System (GPS), which is used in a wide range of industries, including commercial air travel, agriculture, national security, and emergency response. Rocky Stone, chief technical pilot for United Airlines, noted that GPS allows more aircraft to be in airspace, saves fuel, and helps aircraft move safely on runways. “Improvements in space weather forecasting need to be pursued,” he said. Precision GPS has also “changed the whole nature of farming,” said Ron Hatch, Director of Navigation Systems, NavCom Technology/John Deere. GPS makes it possible for tractors to be driven in the most efficient paths and for fertilizer and water to be applied precisely to the areas that most need them. Space weather-induced degradation of GPS signals can cause significant loss to farms that rely on GPS. Elizabeth Zimmerman, Deputy Associate Administrator for the Office of Response and Recovery at the Federal Emergency Management Agency (FEMA), described how FEMA relies on GPS for disaster recovery. The agency is developing an operations plan for dealing with space weather, she said.

A Demonstration of GPS Landslide Monitoring Using Online Positioning User Service (OPUS)

Science.gov (United States)

Wang, G.

2011-12-01

Global Positioning System (GPS) technologies have been frequently applied to landslide study, both as a complement, and as an alternative to conventional surveying methods. However, most applications of GPS for landslide monitoring have been limited to the academic community for research purposes. High-accuracy GPS has not been widely equipped in geotechnical companies and used by technicians. The main issue that limits the applications of GPS in the practice of high-accuracy landslide monitoring is the complexity of GPS data processing. This study demonstrated an approach using the Online Positioning User Service (OPUS) (http://www.ngs.noaa.gov/OPUS) provided by the National Geodetic Survey (NGS) of National Oceanic and Atmospheric Administration (NOAA) to process GPS data and conduct long-term landslide monitoring in the Puerto Rico and Virgin Islands Region. Continuous GPS data collected at a creeping landslide site during two years were used to evaluate different scenarios for landslide surveying: continuous or campaign, long duration or short duration, morning or afternoon (different weather conditions). OPUS uses Continuously Operating Reference Station (CORS) managed by NGS (http://www.ngs.noaa.giv/CORS/) as references and user data as a rover to solve a position. There are 19 CORS permanent GPS stations in the Puerto Rico and Virgin Islands region. The dense GPS network provides a precise and reliable reference frame for subcentimeter-accuracy landslide monitoring in this region. Our criterion for the accuracy was the root-mean-square (RMS) of OPUS solutions over a 2-year period with respect to true landslide displacement time series overt the same period. The true landslide displacements were derived from a single-baseline (130 m) GPS processing by using 24-hour continuous data. If continuous GPS surveying is performed in the field, then OPUS static processing can provide 0.6 cm horizontal and 1.1 cm vertical precision with few outliers. If repeated

The interchangeability of global positioning system and semiautomated video-based performance data during elite soccer match play.

Science.gov (United States)

Harley, Jamie A; Lovell, Ric J; Barnes, Christopher A; Portas, Matthew D; Weston, Matthew

2011-08-01

In elite-level soccer, player motion characteristics are commonly generated from match play and training situations using semiautomated video analysis systems and global positioning system (GPS) technology, respectively. Before such data are used collectively to quantify global player load, it is necessary to understand both the level of agreement and direction of bias between the systems so that specific interventions can be made based on the reported results. The aim of this report was to compare data derived from both systems for physical match performances. Six elite-level soccer players were analyzed during a competitive match using semiautomated video analysis (ProZone® [PZ]) and GPS (MinimaxX) simultaneously. Total distances (TDs), high speed running (HSR), very high speed running (VHSR), sprinting distance (SPR), and high-intensity running distance (HIR; >4.0 m·s(-1)) were reported in 15-minute match periods. The GPS reported higher values than PZ did for TD (GPS: 1,755.4 ± 245.4 m; PZ: 1,631.3 ± 239.5 m; p < 0.05); PZ reported higher values for SPR and HIR than GPS did (SPR: PZ, 34.1 ± 24.0 m; GPS: 20.3 ± 15.8 m; HIR: PZ, 368.1 ± 129.8 m; GPS: 317.0 ± 92.5 m; p < 0.05). Caution should be exercised when using match-load (PZ) and training-load (GPS) data interchangeably.

Determination of global positioning system (GPS) receiver clock errors: impact on positioning accuracy

International Nuclear Information System (INIS)

Yeh, Ta-Kang; Hwang, Cheinway; Xu, Guochang; Wang, Chuan-Sheng; Lee, Chien-Chih

2009-01-01

Enhancing the positioning precision is the primary pursuit of global positioning system (GPS) users. To achieve this goal, most studies have focused on the relationship between GPS receiver clock errors and GPS positioning precision. This study utilizes undifferentiated phase data to calculate GPS clock errors and to compare with the frequency of cesium clock directly, to verify estimated clock errors by the method used in this paper. The frequency stability calculated from this paper (the indirect method) and measured from the National Standard Time and Frequency Laboratory (NSTFL) of Taiwan (the direct method) match to 1.5 × 10 −12 (the value from this study was smaller than that from NSTFL), suggesting that the proposed technique has reached a certain level of quality. The built-in quartz clocks in the GPS receivers yield relative frequency offsets that are 3–4 orders higher than those of rubidium clocks. The frequency stability of the quartz clocks is on average two orders worse than that of the rubidium clock. Using the rubidium clock instead of the quartz clock, the horizontal and vertical positioning accuracies were improved by 26–78% (0.6–3.6 mm) and 20–34% (1.3–3.0 mm), respectively, for a short baseline. These improvements are 7–25% (0.3–1.7 mm) and 11% (1.7 mm) for a long baseline. Our experiments show that the frequency stability of the clock, rather than relative frequency offset, is the governing factor of positioning accuracy

Benefits of Combined GPS/GLONASS with Low-Cost MEMS IMUs for Vehicular Urban Navigation

Directory of Open Access Journals (Sweden)

Giovanni Pugliano

2012-04-01

Full Text Available The integration of Global Navigation Satellite Systems (GNSS with Inertial Navigation Systems (INS has been very actively researched for many years due to the complementary nature of the two systems. In particular, during the last few years the integration with micro-electromechanical system (MEMS inertial measurement units (IMUs has been investigated. In fact, recent advances in MEMS technology have made possible the development of a new generation of low cost inertial sensors characterized by small size and light weight, which represents an attractive option for mass-market applications such as vehicular and pedestrian navigation. However, whereas there has been much interest in the integration of GPS with a MEMS-based INS, few research studies have been conducted on expanding this application to the revitalized GLONASS system. This paper looks at the benefits of adding GLONASS to existing GPS/INS(MEMS systems using loose and tight integration strategies. The relative benefits of various constraints are also assessed. Results show that when satellite visibility is poor (approximately 50% solution availability the benefits of GLONASS are only seen with tight integration algorithms. For more benign environments, a loosely coupled GPS/GLONASS/INS system offers performance comparable to that of a tightly coupled GPS/INS system, but with reduced complexity and development time.

Benefits of combined GPS/GLONASS with low-cost MEMS IMUs for vehicular urban navigation.

Science.gov (United States)

Angrisano, Antonio; Petovello, Mark; Pugliano, Giovanni

2012-01-01

The integration of Global Navigation Satellite Systems (GNSS) with Inertial Navigation Systems (INS) has been very actively researched for many years due to the complementary nature of the two systems. In particular, during the last few years the integration with micro-electromechanical system (MEMS) inertial measurement units (IMUs) has been investigated. In fact, recent advances in MEMS technology have made possible the development of a new generation of low cost inertial sensors characterized by small size and light weight, which represents an attractive option for mass-market applications such as vehicular and pedestrian navigation. However, whereas there has been much interest in the integration of GPS with a MEMS-based INS, few research studies have been conducted on expanding this application to the revitalized GLONASS system. This paper looks at the benefits of adding GLONASS to existing GPS/INS(MEMS) systems using loose and tight integration strategies. The relative benefits of various constraints are also assessed. Results show that when satellite visibility is poor (approximately 50% solution availability) the benefits of GLONASS are only seen with tight integration algorithms. For more benign environments, a loosely coupled GPS/GLONASS/INS system offers performance comparable to that of a tightly coupled GPS/INS system, but with reduced complexity and development time.

Railway automatic safety protection system based on GPS

Directory of Open Access Journals (Sweden)

Fu Hai Juan

2016-01-01

Full Text Available The automatic protection system of railway safety is designed for the railway construction workers to protect alarm, and the safety protection device by using GPS satellite positioning system to acquire location information of the operating point, through the CTC/TDCS system and computer monitoring system for the running of the train position and the arithmetic distance. Achieving timely and continuously forecasts about the distance of the train which is apart from the operating point to prompt the voice alarm of the approaching train. Using digital technology to realize the function of the traditional analog interphone, eliminates the quality problems of the call. With the GSM-R, mobile wireless transmission channel and terminal technology, it overcomes the restrictions of the analog interphone which influenced by communication distance and more problems of blind areas. Finally to achieve practical, convenient, applicable and adaptable design goals.

Signal existence verification (SEV) for GPS low received power signal detection using the time-frequency approach.

Science.gov (United States)

Jan, Shau-Shiun; Sun, Chih-Cheng

2010-01-01

The detection of low received power of global positioning system (GPS) signals in the signal acquisition process is an important issue for GPS applications. Improving the miss-detection problem of low received power signal is crucial, especially for urban or indoor environments. This paper proposes a signal existence verification (SEV) process to detect and subsequently verify low received power GPS signals. The SEV process is based on the time-frequency representation of GPS signal, and it can capture the characteristic of GPS signal in the time-frequency plane to enhance the GPS signal acquisition performance. Several simulations and experiments are conducted to show the effectiveness of the proposed method for low received power signal detection. The contribution of this work is that the SEV process is an additional scheme to assist the GPS signal acquisition process in low received power signal detection, without changing the original signal acquisition or tracking algorithms.

An improvement of the GPS buoy system for detecting tsunami at far offshore

Science.gov (United States)

Kato, T.; Terada, Y.; Nagai, T.; Kawaguchi, K.; Koshimura, S.; Matsushita, Y.

2012-12-01

We have developed a GPS buoy system for detecting a tsunami before its arrival at coasts and thereby mitigating tsunami disaster. The system was first deployed in 1997 for a short period in the Sagami bay, south of Tokyo, for basic experiments, and then deployed off Ofunato city, northeastern part of Japan, for the period 2001-2004. The system was then established at about 13km south of Cape Muroto, southwestern part of Japan, since 2004. Five tsunamis of about 10cm have been observed in these systems, including 2001 Peru earthquake (Mw8.3), 2003 Tokachi-oki earthquake (Mw8.3), 2004 Off Kii Peninsula earthquake (Mw7.4), 2010 Chile earthquake (Mw8.8), and 2011 Tohoku-Oki earthquake (Mw9.0). These experiments clearly showed that GPS buoy is capable of detecting tsunami with a few centimeter accuracy and can be monitored in near real time by applying an appropriate filter, real-time data transmission using radio and dissemination of obtained records of sea surface height changes through internet. Considering that the system is a powerful tool to monitor sea surface variations due to wind as well as tsunami, the Ministry of Land, Infrastructure, Transport and Tourism implemented the system in a part of the Nationwide Ocean Wave information network for Ports and HArbourS (NOWPHAS) system and deployed the system at 15 sites along the coasts around the Japanese Islands. The system detected the tsunami due to the 11th March 2011 Tohoku-Oki earthquake with higher than 6m of tsunami height at the site Off South Iwate (Kamaishi). The Japan Meteorological Agency that was monitoring the record updated the level of the tsunami warning to the greatest value due to the result. Currently, the GPS buoy system uses a RTK-GPS which requires a land base for obtaining precise location of the buoy by a baseline analysis. This algorithm limits the distance of the buoy to, at most, 20km from the coast as the accuracy of positioning gets much worse as the baseline distance becomes longer

An Outdoor Navigation System for Blind Pedestrians Using GPS and Tactile-Foot Feedback

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Ramiro Velázquez

2018-04-01

Full Text Available This paper presents a novel, wearable navigation system for visually impaired and blind pedestrians that combines a global positioning system (GPS for user outdoor localization and tactile-foot stimulation for information presentation. Real-time GPS data provided by a smartphone are processed by dedicated navigation software to determine the directions to a destination. Navigational directions are then encoded as vibrations and conveyed to the user via a tactile display that inserts into the shoe. The experimental results showed that users were capable of recognizing with high accuracy the tactile feedback provided to their feet. The preliminary tests conducted in outdoor locations involved two blind users who were guided along 380–420 m predetermined pathways, while sharing the space with other pedestrians and facing typical urban obstacles. The subjects successfully reached the target destinations. The results suggest that the proposed system enhances independent, safe navigation of blind pedestrians and show the potential of tactile-foot stimulation in assistive devices.

Sensing and Classifying Impairments of GPS Reception on Mobile Devices

DEFF Research Database (Denmark)

Blunck, Henrik; Kjærgaard, Mikkel Baun; Toftegaard, Thomas Skjødeberg

2011-01-01

Positioning using GPS receivers is a primary sensing modality in many areas of pervasive computing. However, previous work has not considered how people’s body impacts the availability and accuracy of GPS positioning and for means to sense such impacts. We present results that the GPS performance...

A design proposal of a certain missile tactical command system based on Beidou satellite communication and GPS positioning techniques

Science.gov (United States)

Ma, Jian; Hao, Yongsheng; Miao, Jian; Zhang, Jianmao

2007-11-01

This paper introduced a design proposal of tactical command system that applied to a kind of anti-tank missile carriers. The tactical command system was made up of embedded computer system based on PC104 bus, Linux operating system, digital military map, Beidou satellite communication equipments and GPS positioning equipments. The geographic coordinates was measured by the GPS receiver, the positioning data, commands and information were transmitted real-time between tactical command systems, tactical command systems and command center, by the Beidou satellite communication systems. The Beidou satellite communication equipments and GPS positioning equipments were integrated to an independent module, exchanging data with embedded computer through RS232 serial ports and USB ports. The decision support system software based on information fusion, calculates positioning data, geography information and battle field information synthetically, shows the position of allies and the position of enemy on the military map, and assesses the various threats of different enemy objects, educes a situation assessment and threat assessment.

Performance Analysis of Measurement Inaccuracies of IMU/GPS on Airborne Repeat-pass Interferometric SAR in the Presence of Squint

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Deng Yuan

2014-08-01

Full Text Available In the MOtion COmpensation (MOCO approach to airborne repeat-pass interferometric Synthetic Aperture Radar (SAR based on motion measurement data, the measurement inaccuracies of Inertial Measurement Unit/Global Positioning System (IMU/GPS and the positioning errors of the target, which may contribute to the residual uncompensated motion errors, affect the imaging result and interferometric measurement. Considering the effects of the two types of error, this paper builds a mathematical model of residual motion errors in presence of squint, and analyzes the effects on the residual motion errors induced by the measurement inaccuracies of IMU/GPS and the positioning errors of the target. In particular, the effects of various measurement inaccuracies of IMU/GPS on interferometric SAR image quality, interferometric phase, and digital elevation model precision are disscussed. Moreover, the paper quantitatively researches the effects of residual motion errors on airborne repeat-pass interferometric SAR through theoretical and simulated analyses and provides theoretical bases for system design and signal processing.

Performance enhancement of low-cost, high-accuracy, state estimation for vehicle collision prevention system using ANFIS

Science.gov (United States)

Saadeddin, Kamal; Abdel-Hafez, Mamoun F.; Jaradat, Mohammad A.; Jarrah, Mohammad Amin

2013-12-01

In this paper, a low-cost navigation system that fuses the measurements of the inertial navigation system (INS) and the global positioning system (GPS) receiver is developed. First, the system's dynamics are obtained based on a vehicle's kinematic model. Second, the INS and GPS measurements are fused using an extended Kalman filter (EKF) approach. Subsequently, an artificial intelligence based approach for the fusion of INS/GPS measurements is developed based on an Input-Delayed Adaptive Neuro-Fuzzy Inference System (IDANFIS). Experimental tests are conducted to demonstrate the performance of the two sensor fusion approaches. It is found that the use of the proposed IDANFIS approach achieves a reduction in the integration development time and an improvement in the estimation accuracy of the vehicle's position and velocity compared to the EKF based approach.

Global Positioning System (GPS) Energetic Particle Data

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Energetic particle data from the CXD and BDD instrument on the GPS constellation are available to the space weather research community. The release of these data...

Development And Test of A Digitally Steered Antenna Array for The Navigator GPS Receiver

Science.gov (United States)

Pinto, Heitor David; Valdez, Jennifer E.; Winternitz, Luke M. B.; Hassouneh, Munther A.; Price, Samuel R.

2012-01-01

Global Positioning System (GPS)-based navigation has become common for low-Earth orbit spacecraft as the signal environment is similar to that on the Earth s surface. The situation changes abruptly, however, for spacecraft whose orbital altitudes exceed that of the GPS constellation. Visibility is dramatically reduced and signals that are present may be very weak and more susceptible to interference. GPS receivers effective at these altitudes require increased sensitivity, which often requires a high-gain antenna. Pointing such an antenna can pose a challenge. One efficient approach to mitigate these problems is the use of a digitally steered antenna array. Such an antenna can optimally allocate gain toward desired signal sources and away from interferers. This paper presents preliminary results in the development and test of a digitally steered antenna array for the Navigator GPS research program at NASA s Goddard Space Flight Center. In particular, this paper highlights the development of an array and front-end electronics, the development and test of a real-time software GPS receiver, and implementation of three beamforming methods for combining the signals from the array. Additionally, this paper discusses the development of a GPS signal simulator which produces digital samples of the GPS L1C/A signals as they would be received by an arbitrary antenna array configuration. The simulator models transmitter and receiver dynamics, near-far and multipath interference, and has been a critical component in both the development and test of the GPS receiver. The GPS receiver system was tested with real and simulated GPS signals. Preliminary results show that performance improvement was achieved in both the weak signal and interference environments, matching analytical predictions. This paper summarizes our initial findings and discusses the advantages and limitations of the antenna array and the various beamforming methods.

77 FR 56254 - 89th Meeting: RTCA Special Committee 159, Global Positioning Systems (GPS)

Science.gov (United States)

2012-09-12

... held March 16, 2012. Review Working Group (WG) Progress and Identify Issues for Resolution. GPS/3nd... Standards for Global Positioning System/Wide Area Augmentation System Airborne Equipment Assignment/Review of Future Work. Other Business. Date and Place of Next Meeting. Adjourn Attendance is open to the...

77 FR 23668 - GPS Satellite Simulator Working Group Notice of Meeting

Science.gov (United States)

2012-04-20

... DEPARTMENT OF DEFENSE Department of the Air Force GPS Satellite Simulator Working Group Notice of... inform the public that the Global Positioning Systems (GPS) Directorate will be hosting an open GPS Satellite Simulator Working Group (SSWG) meeting for manufacturers of GPS constellation simulators utilized...

GPS Modeling and Analysis. Summary of Research: GPS Satellite Axial Ratio Predictions

Science.gov (United States)

Axelrad, Penina; Reeh, Lisa

2002-01-01

This report outlines the algorithms developed at the Colorado Center for Astrodynamics Research to model yaw and predict the axial ratio as measured from a ground station. The algorithms are implemented in a collection of Matlab functions and scripts that read certain user input, such as ground station coordinates, the UTC time, and the desired GPS (Global Positioning System) satellites, and compute the above-mentioned parameters. The position information for the GPS satellites is obtained from Yuma almanac files corresponding to the prescribed date. The results are displayed graphically through time histories and azimuth-elevation plots.

Interseismic Coupling on the Quito Fault System in Ecuador Using New GPS and InSAR Data and Its Implication on Seismic Hazard Assessment.

Science.gov (United States)

Mariniere, J.; Champenois, J.; Nocquet, J. M.; Beauval, C. M.; Audin, L.; Baize, S.; Alvarado, A. P.; Yepes, H. A.; Jomard, H.

2017-12-01

Quito, the capital of Ecuador hosting two million inhabitants lies on an active reverse fault system within the Andes. Regular moderate size earthquakes (M 5) occur on these faults, widely felt within the city and its surrounding. Despite a relatively small magnitude of Mw 5.1, the 2014 August 12 earthquake triggered landslides that killed 4 people, cut off one of the main highways for several weeks and caused the temporary shutdown of the airport. Quantifying the seismic potential of the Quito fault system is therefore crucial for a better preparation and mitigation to seismic risk. Previous work using a limited GPS data set found that the Quito fault accommodates 4 mm/yr of EW shortening (Alvarado et al., 2014) at shallow locking depths (3-7 km). We combine GPS and new InSAR data to extend the previous analysis and better quantify the spatial distribution of locking of the Quito fault. GPS dataset includes new continuous sites operating since 2013. 18 ERS SAR scenes, spanning the 1993-2000 time period and covering an area of 85 km by 30 km, were processed using a Permanent Scatter strategy. We perform a joint inversion of both data set (GPS and InSAR) to infer a new and better-constrained kinematic model of the fault to determine both the slip rate and the locking distribution at depth. We find a highly variable level of locking which changes along strike. At some segments, sharp displacement gradients observed both for GPS and InSAR suggest that the fault is creeping up to the surface, while shallow locking is found for other segments. Previous Probabilistic Seismic Hazard Assessment studies have shown that the Quito fault fully controls the hazard in Quito city (Beauval et al. 2014). The results will be used to improve the forecast of earthquakes on the Quito fault system for PSHA studies.

Observability analysis of a MEMS INS/GPS integration system with gyroscope G-sensitivity errors.

Science.gov (United States)

Fan, Chen; Hu, Xiaoping; He, Xiaofeng; Tang, Kanghua; Luo, Bing

2014-08-28

Gyroscopes based on micro-electromechanical system (MEMS) technology suffer in high-dynamic applications due to obvious g-sensitivity errors. These errors can induce large biases in the gyroscope, which can directly affect the accuracy of attitude estimation in the integration of the inertial navigation system (INS) and the Global Positioning System (GPS). The observability determines the existence of solutions for compensating them. In this paper, we investigate the observability of the INS/GPS system with consideration of the g-sensitivity errors. In terms of two types of g-sensitivity coefficients matrix, we add them as estimated states to the Kalman filter and analyze the observability of three or nine elements of the coefficient matrix respectively. A global observable condition of the system is presented and validated. Experimental results indicate that all the estimated states, which include position, velocity, attitude, gyro and accelerometer bias, and g-sensitivity coefficients, could be made observable by maneuvering based on the conditions. Compared with the integration system without compensation for the g-sensitivity errors, the attitude accuracy is raised obviously.

Observability Analysis of a MEMS INS/GPS Integration System with Gyroscope G-Sensitivity Errors

Directory of Open Access Journals (Sweden)

Chen Fan

2014-08-01

Full Text Available Gyroscopes based on micro-electromechanical system (MEMS technology suffer in high-dynamic applications due to obvious g-sensitivity errors. These errors can induce large biases in the gyroscope, which can directly affect the accuracy of attitude estimation in the integration of the inertial navigation system (INS and the Global Positioning System (GPS. The observability determines the existence of solutions for compensating them. In this paper, we investigate the observability of the INS/GPS system with consideration of the g-sensitivity errors. In terms of two types of g-sensitivity coefficients matrix, we add them as estimated states to the Kalman filter and analyze the observability of three or nine elements of the coefficient matrix respectively. A global observable condition of the system is presented and validated. Experimental results indicate that all the estimated states, which include position, velocity, attitude, gyro and accelerometer bias, and g-sensitivity coefficients, could be made observable by maneuvering based on the conditions. Compared with the integration system without compensation for the g-sensitivity errors, the attitude accuracy is raised obviously.

Why GPS makes distances bigger than they are.

Science.gov (United States)

Ranacher, Peter; Brunauer, Richard; Trutschnig, Wolfgang; Van der Spek, Stefan; Reich, Siegfried

2016-02-01

Global navigation satellite systems such as the Global Positioning System (GPS) is one of the most important sensors for movement analysis. GPS is widely used to record the trajectories of vehicles, animals and human beings. However, all GPS movement data are affected by both measurement and interpolation errors. In this article we show that measurement error causes a systematic bias in distances recorded with a GPS; the distance between two points recorded with a GPS is - on average - bigger than the true distance between these points. This systematic 'overestimation of distance' becomes relevant if the influence of interpolation error can be neglected, which in practice is the case for movement sampled at high frequencies. We provide a mathematical explanation of this phenomenon and illustrate that it functionally depends on the autocorrelation of GPS measurement error ( C ). We argue that C can be interpreted as a quality measure for movement data recorded with a GPS. If there is a strong autocorrelation between any two consecutive position estimates, they have very similar error. This error cancels out when average speed, distance or direction is calculated along the trajectory. Based on our theoretical findings we introduce a novel approach to determine C in real-world GPS movement data sampled at high frequencies. We apply our approach to pedestrian trajectories and car trajectories. We found that the measurement error in the data was strongly spatially and temporally autocorrelated and give a quality estimate of the data. Most importantly, our findings are not limited to GPS alone. The systematic bias and its implications are bound to occur in any movement data collected with absolute positioning if interpolation error can be neglected.

Implementasi Sistem Pelacakan Kendaraan Bermotor Menggunakan Gps Dan Gprs Dengan Integrasi Googlemap

Directory of Open Access Journals (Sweden)

Yazid Dul Muchlisin

2011-07-01

Full Text Available Abstract— Vehicle tracking system using GPS and GPRS integration googlemap provide information that is maximized with the technology of GPS (Global Positioning System receiver which can indicate the position of the vehicle with the map and the ability of the appointment of direction and position coordinates (x, y or latitude, longitude textually and visual at any location. Vehicle tracking system is built using equipment GIS (Geographic Information System and dedicated to smartphones which support Global Positioning System (GPS, as well as portable computers, using General Packet Radio Service (GPRS as a connection to the internet. The hardware used is a smartphone that supports GPS with supporting tools used are GoogleMaps, Notepad + +, NetBeans IDE 6.5.1, Mysql, Java (J2ME, PHP, JavaScript. The results of this system in the form of tracking system capable of monitoring the movement of vehicles on an ongoing position by utilizing GPS and GPRS as the sender of the wireless data and Internet connections.   Keywords— GIS, GPS, GPRS, googlemaps, J2ME,

Demonstration of coherent Doppler lidar for navigation in GPS-denied environments

Science.gov (United States)

Amzajerdian, Farzin; Hines, Glenn D.; Pierrottet, Diego F.; Barnes, Bruce W.; Petway, Larry B.; Carson, John M.

2017-05-01

A coherent Doppler lidar has been developed to address NASA's need for a high-performance, compact, and cost-effective velocity and altitude sensor onboard its landing vehicles. Future robotic and manned missions to solar system bodies require precise ground-relative velocity vector and altitude data to execute complex descent maneuvers and safe, soft landing at a pre-designated site. This lidar sensor, referred to as a Navigation Doppler Lidar (NDL), meets the required performance of the landing missions while complying with vehicle size, mass, and power constraints. Operating from up to four kilometers altitude, the NDL obtains velocity and range precision measurements reaching 2 cm/sec and 2 meters, respectively, dominated by the vehicle motion. Terrestrial aerial vehicles will also benefit from NDL data products as enhancement or replacement to GPS systems when GPS is unavailable or redundancy is needed. The NDL offers a viable option to aircraft navigation in areas where the GPS signal can be blocked or jammed by intentional or unintentional interference. The NDL transmits three laser beams at different pointing angles toward the ground to measure range and velocity along each beam using a frequency modulated continuous wave (FMCW) technique. The three line-of-sight measurements are then combined in order to determine the three components of the vehicle velocity vector and its altitude relative to the ground. This paper describes the performance and capabilities that the NDL demonstrated through extensive ground tests, helicopter flight tests, and onboard an autonomous rocket-powered test vehicle while operating in closedloop with a guidance, navigation, and control (GN and C) system.

Accuracy assessment of high-rate GPS measurements for seismology

Science.gov (United States)

Elosegui, P.; Davis, J. L.; Ekström, G.

2007-12-01

Analysis of GPS measurements with a controlled laboratory system, built to simulate the ground motions caused by tectonic earthquakes and other transient geophysical signals such as glacial earthquakes, enables us to assess the technique of high-rate GPS. The root-mean-square (rms) position error of this system when undergoing realistic simulated seismic motions is 0.05~mm, with maximum position errors of 0.1~mm, thus providing "ground truth" GPS displacements. We have acquired an extensive set of high-rate GPS measurements while inducing seismic motions on a GPS antenna mounted on this system with a temporal spectrum similar to real seismic events. We found that, for a particular 15-min-long test event, the rms error of the 1-Hz GPS position estimates was 2.5~mm, with maximum position errors of 10~mm, and the error spectrum of the GPS estimates was approximately flicker noise. These results may however represent a best-case scenario since they were obtained over a short (~10~m) baseline, thereby greatly mitigating baseline-dependent errors, and when the number and distribution of satellites on the sky was good. For example, we have determined that the rms error can increase by a factor of 2--3 as the GPS constellation changes throughout the day, with an average value of 3.5~mm for eight identical, hourly-spaced, consecutive test events. The rms error also increases with increasing baseline, as one would expect, with an average rms error for a ~1400~km baseline of 9~mm. We will present an assessment of the accuracy of high-rate GPS based on these measurements, discuss the implications of this study for seismology, and describe new applications in glaciology.

Optimization Controller for Mechatronic Sun Tracking System to Improve Performance

Directory of Open Access Journals (Sweden)

Mustafa Engin

2013-01-01

Full Text Available An embedded system that contains hardware and software was developed for two-axis solar tracking system to improve photovoltaic panel utilization. The hardware section of the embedded system consists of a 32-bit ARM core microcontroller, motor driver circuits, a motion control unit, pyranometer, GPS receiver, and an anemometer. The real-time control algorithm enables the solar tracker to operate automatically without external control as a stand-alone system, combining the advantages of the open-loop and the closed-loop control methods. The pyranometer is employed to continuously send radiation data to the controller if the measured radiation is above the lower radiation limit the photovoltaic panel can generate power, guaranteeing the solar tracking process to be highly efficient. The anemometer is utilized in the system to ensure that the solar tracking procedure halts under high wind speed conditions to protect the entire system. Latitude, longitude, altitude, date, and real-time clock data are provided by GPS receiver. The algorithm calculates solar time using astronomical equations with GPS data and converts it to pulse-width modulated motor control signal. The overall objective of this study is to develop a control algorithm that improves performance and reliability of the two-axis solar tracker, focusing on optimization of the controller board, drive hardware, and software.

GPS Usage in a Population of Low-Vision Drivers.

Science.gov (United States)

Cucuras, Maria; Chun, Robert; Lee, Patrick; Jay, Walter M; Pusateri, Gregg

2017-01-01

We surveyed bioptic and non-bioptic low-vision drivers in Illinois, USA, to determine their usage of global positioning system (GPS) devices. Low-vision patients completed an IRB-approved phone survey regarding driving demographics and usage of GPS while driving. Participants were required to be active drivers with an Illinois driver's license, and met one of the following criteria: best-corrected visual acuity (BCVA) less than or equal to 20/40, central or significant peripheral visual field defects, or a combination of both. Of 27 low-vision drivers, 10 (37%) used GPS while driving. The average age for GPS users was 54.3 and for non-users was 77.6. All 10 drivers who used GPS while driving reported increased comfort or safety level. Since non-GPS users were significantly older than GPS users, it is likely that older participants would benefit from GPS technology training from their low-vision eye care professionals.

Impact of a high density GPS network on the operational forecast

Directory of Open Access Journals (Sweden)

C. Faccani

2005-01-01

Full Text Available Global Positioning System Zenith Total Delay (GPS ZTD can provide information about the water vapour in atmosphere. Its assimilation into the analysis used to initialize a model can then improve the weather forecast, giving the right amount of moisture and reducing the model spinup. In the last year, an high density GPS network has been created on the Basilicata region (south of Italy by the Italian Space Agency in the framework of a national project named MAGIC2. MAGIC2 is the Italian follow on of the EC project MAGIC has. Daily operational data assimilation experiments are performed since December 2003. The results show that the assimilation of GPS ZTD improves the forecast especially during the transition from winter to spring even if a no very high model resolution (9km is used.

Comparison of GLONASS and GPS Time Transfers

Science.gov (United States)

Daly, P.; Koshelyaevsky, N. B.; Lewandowski, W.; Petit, G.; Thomas, C.

1993-01-01

The Russian global space navigation system GLONASS could provide a technique similar to GPS for international time comparison. The main limitation to its use for time transfer is the lack of commercially available time receivers. The University of Leeds built a GPS/GLONASS receiver five years ago and since then has provided continuous information about GLONASS time and its comparison with GPS time. For the last two years the VNIIFTRI and several other Russian time laboratories have used Russian-built GLONASS navigation receivers for time comparisons. Since June 1991, the VNIIFTRI has operated a GPS time receiver which offers, for the first time, an opportunity for the direct comparison of time transfers using GPS and GLONASS. This seven-month experiment shows that even with relatively imprecise data recording and processing, in terms of time metrology, GLONASS can provide continental time transfer at a level of several tens of nanoseconds.

GPS/MEMS IMU/Microprocessor Board for Navigation

Science.gov (United States)

Gender, Thomas K.; Chow, James; Ott, William E.

2009-01-01

A miniaturized instrumentation package comprising a (1) Global Positioning System (GPS) receiver, (2) an inertial measurement unit (IMU) consisting largely of surface-micromachined sensors of the microelectromechanical systems (MEMS) type, and (3) a microprocessor, all residing on a single circuit board, is part of the navigation system of a compact robotic spacecraft intended to be released from a larger spacecraft [e.g., the International Space Station (ISS)] for exterior visual inspection of the larger spacecraft. Variants of the package may also be useful in terrestrial collision-detection and -avoidance applications. The navigation solution obtained by integrating the IMU outputs is fed back to a correlator in the GPS receiver to aid in tracking GPS signals. The raw GPS and IMU data are blended in a Kalman filter to obtain an optimal navigation solution, which can be supplemented by range and velocity data obtained by use of (l) a stereoscopic pair of electronic cameras aboard the robotic spacecraft and/or (2) a laser dynamic range imager aboard the ISS. The novelty of the package lies mostly in those aspects of the design of the MEMS IMU that pertain to controlling mechanical resonances and stabilizing scale factors and biases.

How GPs value guidelines applied to patients with multimorbidity: a qualitative study.

Science.gov (United States)

Luijks, Hilde; Lucassen, Peter; van Weel, Chris; Loeffen, Maartje; Lagro-Janssen, Antoine; Schermer, Tjard

2015-10-26

To explore and describe the value general practitioner (GPs) attribute to medical guidelines when they are applied to patients with multimorbidity, and to describe which benefits GPs experience from guideline adherence in these patients. Also, we aimed to identify limitations from guideline adherence in patients with multimorbidity, as perceived by GPs, and to describe their empirical solutions to manage these obstacles. Focus group study with purposive sampling of participants. Focus groups were guided by an experienced moderator who used an interview guide. Interviews were transcribed verbatim. Data analysis was performed by two researchers using the constant comparison analysis technique and field notes were used in the analysis. Data collection proceeded until saturation was reached. Primary care, eastern part of The Netherlands. Dutch GPs, heterogeneous in age, sex and academic involvement. 25 GPs participated in five focus groups. GPs valued the guidance that guidelines provide, but experienced shortcomings when they were applied to patients with multimorbidity. Taking these patients' personal circumstances into account was regarded as important, but it was impeded by a consistent focus on guideline adherence. Preventative measures were considered less appropriate in (elderly) patients with multimorbidity. Moreover, the applicability of guidelines in patients with multimorbidity was questioned. GPs' extensive practical experience with managing multimorbidity resulted in several empirical solutions, for example, using their 'common sense' to respond to the perceived shortcomings. GPs applying guidelines for patients with multimorbidity integrate patient-specific factors in their medical decisions, aiming for patient-centred solutions. Such integration of clinical experience and best evidence is required to practise evidence-based medicine. More flexibility in pay-for-performance systems is needed to facilitate this integration. Several improvements in

GPS Water Vapor Tomography Based on Accurate Estimations of the GPS Tropospheric Parameters

Science.gov (United States)

Champollion, C.; Masson, F.; Bock, O.; Bouin, M.; Walpersdorf, A.; Doerflinger, E.; van Baelen, J.; Brenot, H.

2003-12-01

The Global Positioning System (GPS) is now a common technique for the retrieval of zenithal integrated water vapor (IWV). Further applications in meteorology need also slant integrated water vapor (SIWV) which allow to precisely define the high variability of tropospheric water vapor at different temporal and spatial scales. Only precise estimations of IWV and horizontal gradients allow the estimation of accurate SIWV. We present studies developed to improve the estimation of tropospheric water vapor from GPS data. Results are obtained from several field experiments (MAP, ESCOMPTE, OHM-CV, IHOP, .). First IWV are estimated using different GPS processing strategies and results are compared to radiosondes. The role of the reference frame and the a priori constraints on the coordinates of the fiducial and local stations is generally underestimated. It seems to be of first order in the estimation of the IWV. Second we validate the estimated horizontal gradients comparing zenith delay gradients and single site gradients. IWV, gradients and post-fit residuals are used to construct slant integrated water delays. Validation of the SIWV is under progress comparing GPS SIWV, Lidar measurements and high resolution meteorological models (Meso-NH). A careful analysis of the post-fit residuals is needed to separate tropospheric signal from multipaths. The slant tropospheric delays are used to study the 3D heterogeneity of the troposphere. We develop a tomographic software to model the three-dimensional distribution of the tropospheric water vapor from GPS data. The software is applied to the ESCOMPTE field experiment, a dense network of 17 dual frequency GPS receivers operated in southern France. Three inversions have been successfully compared to three successive radiosonde launches. Good resolution is obtained up to heights of 3000 m.

Enhancing the accuracy of GPS point positioning by converting the single frequency data to dual frequency data

Directory of Open Access Journals (Sweden)

Aly M. El-naggar

2011-09-01

Full Text Available The global positioning system (GPS has been used to support a wide variety of applications, such as high-accuracy positioning and navigation. Differential GPS techniques can largely eliminate common-mode errors between the reference and the rover GPS stations resulting from ionospheric and tropospheric refraction and delays, satellite and receiver clock biases, and orbital errors [1]. The ionospheric delay in the propagation of global positioning system (GPS signals is one of the main sources of error in GPS precise positioning and navigation. A dual-frequency GPS receiver can eliminate (to the first order the ionospheric delay through a linear combination of the L1 and L2 observations [2]. The most significant effect of ionospheric delay appear in case of using single frequency data. In this paper the single frequency data of concerned station are converted to dual frequency data by employing dual frequency data from 11 regional GPS stations distributed around it. Total electron content (TEC was calculated at every GPS station to produce the mathematical model of TEC which is a function of latitude (Φ and longitude (λ. By using this mathematical model the values of TEC and L2 can be predicted at the single frequency GPS station for each satellite, after that the comparison between predicted and observation values of TEC and L2 was performed. The estimation method and test results of the proposed method indicates that the difference between predicted and observation values is very small.

A pilot study using global positioning systems (GPS) devices and surveys to ascertain older adults' travel patterns.

Science.gov (United States)

Yen, Irene H; Leung, Cindy W; Lan, Mars; Sarrafzadeh, Majid; Kayekjian, Karen C; Duru, O Kenrik

2015-04-01

Some studies indicate that older adults lead active lives and travel to many destinations including those not in their immediate residential neighborhoods. We used global positioning system (GPS) devices to track the travel patterns of 40 older adults (mean age: 69) in San Francisco and Los Angeles. Study participants wore the GPS devices for 7 days in fall 2010 and winter 2011. We collected survey responses concurrently about travel patterns. GPS data showed a mean of four trips/day, and a mean trip distance of 7.6 km. Survey data indicated that older adults commonly made trips for four activities (e.g., volunteering, work, visiting friends) at least once each week. Older adults regularly travel outside their residential neighborhoods. GPS can document the mode of travel, the path of travel, and the destinations. Surveys can document the purpose of the travel and the impressions or experiences in the specific locations. © The Author(s) 2013.

An improved grey model for the prediction of real-time GPS satellite clock bias

Science.gov (United States)

Zheng, Z. Y.; Chen, Y. Q.; Lu, X. S.

2008-07-01

In real-time GPS precise point positioning (PPP), real-time and reliable satellite clock bias (SCB) prediction is a key to implement real-time GPS PPP. It is difficult to hold the nuisance and inenarrable performance of space-borne GPS satellite atomic clock because of its high-frequency, sensitivity and impressionable, it accords with the property of grey model (GM) theory, i. e. we can look on the variable process of SCB as grey system. Firstly, based on limits of quadratic polynomial (QP) and traditional GM to predict SCB, a modified GM (1,1) is put forward to predict GPS SCB in this paper; and then, taking GPS SCB data for example, we analyzed clock bias prediction with different sample interval, the relationship between GM exponent and prediction accuracy, precision comparison of GM to QP, and concluded the general rule of different type SCB and GM exponent; finally, to test the reliability and validation of the modified GM what we put forward, taking IGS clock bias ephemeris product as reference, we analyzed the prediction precision with the modified GM, It is showed that the modified GM is reliable and validation to predict GPS SCB and can offer high precise SCB prediction for real-time GPS PPP.

Ionospheric correction for spaceborne single-frequency GPS based ...

Indian Academy of Sciences (India)

A modified ionospheric correction method and the corresponding approximate algorithm for spaceborne single-frequency Global Positioning System (GPS) users are proposed in this study. Single Layer Model (SLM) mapping function for spaceborne GPS was analyzed. SLM mapping functions at different altitudes were ...

Improving Ambiguity Resolution for Medium Baselines Using Combined GPS and BDS Dual/Triple-Frequency Observations.

Science.gov (United States)

Gao, Wang; Gao, Chengfa; Pan, Shuguo; Wang, Denghui; Deng, Jiadong

2015-10-30

The regional constellation of the BeiDou navigation satellite system (BDS) has been providing continuous positioning, navigation and timing services since 27 December 2012, covering China and the surrounding area. Real-time kinematic (RTK) positioning with combined BDS and GPS observations is feasible. Besides, all satellites of BDS can transmit triple-frequency signals. Using the advantages of multi-pseudorange and carrier observations from multi-systems and multi-frequencies is expected to be of much benefit for ambiguity resolution (AR). We propose an integrated AR strategy for medium baselines by using the combined GPS and BDS dual/triple-frequency observations. In the method, firstly the extra-wide-lane (EWL) ambiguities of triple-frequency system, i.e., BDS, are determined first. Then the dual-frequency WL ambiguities of BDS and GPS were resolved with the geometry-based model by using the BDS ambiguity-fixed EWL observations. After that, basic (i.e., L1/L2 or B1/B2) ambiguities of BDS and GPS are estimated together with the so-called ionosphere-constrained model, where the ambiguity-fixed WL observations are added to enhance the model strength. During both of the WL and basic AR, a partial ambiguity fixing (PAF) strategy is adopted to weaken the negative influence of new-rising or low-elevation satellites. Experiments were conducted and presented, in which the GPS/BDS dual/triple-frequency data were collected in Nanjing and Zhengzhou of China, with the baseline distance varying from about 28.6 to 51.9 km. The results indicate that, compared to the single triple-frequency BDS system, the combined system can significantly enhance the AR model strength, and thus improve AR performance for medium baselines with a 75.7% reduction of initialization time on average. Besides, more accurate and stable positioning results can also be derived by using the combined GPS/BDS system.

Comparing Global Positioning System (GPS) and Global Navigation Satellite System (GNSS) Measures of Team Sport Movements.

Science.gov (United States)

Jackson, Benjamin M; Polglaze, Ted; Dawson, Brian; King, Trish; Peeling, Peter

2018-02-21

To compare data from conventional GPS and new GNSS-enabled tracking devices, and to examine the inter-unit reliability of GNSS devices. Inter-device differences between 10 Hz GPS and GNSS devices were examined during laps (n=40) of a simulated game circuit (SGC) and during elite hockey matches (n=21); GNSS inter-unit reliability was also examined during the SGC laps. Differences in distance values and measures in three velocity categories (low 5 m.s -1 ) and acceleration/deceleration counts (>1.46 m.s -2 and GPS devices in all conditions. These findings suggest that GNSS devices may be more sensitive than GPS in quantifying the physical demands of team sport movements, but further study into the accuracy of GNSS devices is required.

Relationships between GPS-signal propagation errors and EISCAT observations

Directory of Open Access Journals (Sweden)

N. Jakowski

1996-12-01

Full Text Available When travelling through the ionosphere the signals of space-based radio navigation systems such as the Global Positioning System (GPS are subject to modifications in amplitude, phase and polarization. In particular, phase changes due to refraction lead to propagation errors of up to 50 m for single-frequency GPS users. If both the L1 and the L2 frequencies transmitted by the GPS satellites are measured, first-order range error contributions of the ionosphere can be determined and removed by difference methods. The ionospheric contribution is proportional to the total electron content (TEC along the ray path between satellite and receiver. Using about ten European GPS receiving stations of the International GPS Service for Geodynamics (IGS, the TEC over Europe is estimated within the geographic ranges -20°≤ λ ≤40°E and 32.5°≤ Φ ≤70°N in longitude and latitude, respectively. The derived TEC maps over Europe contribute to the study of horizontal coupling and transport proces- ses during significant ionospheric events. Due to their comprehensive information about the high-latitude ionosphere, EISCAT observations may help to study the influence of ionospheric phenomena upon propagation errors in GPS navigation systems. Since there are still some accuracy limiting problems to be solved in TEC determination using GPS, data comparison of TEC with vertical electron density profiles derived from EISCAT observations is valuable to enhance the accuracy of propagation-error estimations. This is evident both for absolute TEC calibration as well as for the conversion of ray-path-related observations to vertical TEC. The combination of EISCAT data and GPS-derived TEC data enables a better understanding of large-scale ionospheric processes.

Effect of forest canopy on GPS-based movement data

Science.gov (United States)

Nicholas J. DeCesare; John R. Squires; Jay A. Kolbe

2005-01-01

The advancing role of Global Positioning System (GPS) technology in ecology has made studies of animal movement possible for larger and more vagile species. A simple field test revealed that lengths of GPS-based movement data were strongly biased (Pof forest canopy. Global Positioning System error added an average of 27.5% additional...

Development of a Real-Time GPS/Seismic Displacement Meter: Seismic Component and Communications

Science.gov (United States)

Vernon, F.; Bock, Y.

2002-12-01

In two abstracts, we report on an ongoing effort to develop an Integrated Real-Time GPS/Seismic System for Orange and Western Riverside Counties, California, spanning three major strike-slip faults in southern California (San Andreas, San Jacinto, and Elsinore) and significant populations and civilian infrastructure. The system relying on existing GPS and seismic networks will collect and analyze GPS and seismic data for the purpose of estimating and disseminating real-time positions and total ground displacements (dynamic, as well as static) covering all phases of the seismic cycle, from fractions of seconds to years. Besides its intrinsic scientific use as a real-time displacement meter (transducer), the GPS/Seismic System will be a powerful tool for local and state decision makers for risk mitigation, disaster management, and structural monitoring (dams, bridges, and buildings). Furthermore, the GPS/Seismic System will become an integral part of California's spatial referencing and positioning infrastructure, which is complicated by tectonic motion, seismic displacements, and land subsidence. This development is taking place under the umbrella of the California Spatial Reference Center, in partnership with local (The Counties, Riverside County Flood and Water Conservation District, Southern California Metropolitan Water District), state (Caltrans), and Federal agencies (NGS, NASA, USGS), the geophysics community (SCEC2/SCIGN), and the private sector (RBF Consulting). The project is leveraging considerable funding, resources, and research and development from SCIGN, CSRC and two NSF-funded IT projects at UCSD and SDSU: RoadNet (Real-Time Observatories, Applications and Data Management Network) and the High Performance Wireless Research and Education Network (HPWREN). These two projects are funded to develop both the wireless networks and the integrated, seamless, and transparent information management system that will deliver seismic, geodetic, oceanographic

MDOT implementation plan for global positioning systems (GPS) technology in planning, design, and construction delivery.

Science.gov (United States)

2010-09-13

Global Positioning System (GPS) technology offers advantages to transportation agencies in the planning, design and construction stages of project delivery. This research study will develop a guide for Mississippi Department of Transportation (MDOT) ...

Fast-Acquisition/Weak-Signal-Tracking GPS Receiver for HEO

Science.gov (United States)

Wintemitz, Luke; Boegner, Greg; Sirotzky, Steve

2004-01-01

A report discusses the technical background and design of the Navigator Global Positioning System (GPS) receiver -- . a radiation-hardened receiver intended for use aboard spacecraft. Navigator is capable of weak signal acquisition and tracking as well as much faster acquisition of strong or weak signals with no a priori knowledge or external aiding. Weak-signal acquisition and tracking enables GPS use in high Earth orbits (HEO), and fast acquisition allows for the receiver to remain without power until needed in any orbit. Signal acquisition and signal tracking are, respectively, the processes of finding and demodulating a signal. Acquisition is the more computationally difficult process. Previous GPS receivers employ the method of sequentially searching the two-dimensional signal parameter space (code phase and Doppler). Navigator exploits properties of the Fourier transform in a massively parallel search for the GPS signal. This method results in far faster acquisition times [in the lab, 12 GPS satellites have been acquired with no a priori knowledge in a Low-Earth-Orbit (LEO) scenario in less than one second]. Modeling has shown that Navigator will be capable of acquiring signals down to 25 dB-Hz, appropriate for HEO missions. Navigator is built using the radiation-hardened ColdFire microprocessor and housing the most computationally intense functions in dedicated field-programmable gate arrays. The high performance of the algorithm and of the receiver as a whole are made possible by optimizing computational efficiency and carefully weighing tradeoffs among the sampling rate, data format, and data-path bit width.

An investigation of airborne GPS/INS for high accuracy position and velocity determination

Energy Technology Data Exchange (ETDEWEB)

Sun, H.; Cannon, M.E. [Calgary Univ., AB (Canada). Dept. of Geomatics Engineering; Owen, T.E.; Meindl, M.A. [Sandia National Labs., Albuquerque, NM (United States)

1993-12-31

An airborne test using a differential GPS-INS system in a Twin Otter was conducted by Sandia National Laboratories to assess the feasibility of using the integrated system for cm-level position and cm/s velocity. The INS is a miniaturized ring-laser gyro IMU jointly developed by Sandia and Honeywell while the GPS system consists of the NovAtel GPSCard{trademark}. INS position, velocity and attitude data were computed using Sandia`s SANDAC flight computer system and logged at 4 Hz and GPS data was acquired at a 1 Hz rate. The mission was approximately 2.5 hours in duration and the aircraft reached separations of up to 19 km from the base station. The data was post-processed using a centralized Kalman filter approach in which the double differenced carrier phase measurements are used to update the INS data. The INS position is in turn used to detect and correct GPS carrier phase cycle slips and also to bridge GPS outages. Results are presented for the GPS-only case and also for integrated GPS/INS.

Physical applications of GPS geodesy: a review.

Science.gov (United States)

Bock, Yehuda; Melgar, Diego

2016-10-01

Geodesy, the oldest science, has become an important discipline in the geosciences, in large part by enhancing Global Positioning System (GPS) capabilities over the last 35 years well beyond the satellite constellation's original design. The ability of GPS geodesy to estimate 3D positions with millimeter-level precision with respect to a global terrestrial reference frame has contributed to significant advances in geophysics, seismology, atmospheric science, hydrology, and natural hazard science. Monitoring the changes in the positions or trajectories of GPS instruments on the Earth's land and water surfaces, in the atmosphere, or in space, is important for both theory and applications, from an improved understanding of tectonic and magmatic processes to developing systems for mitigating the impact of natural hazards on society and the environment. Besides accurate positioning, all disturbances in the propagation of the transmitted GPS radio signals from satellite to receiver are mined for information, from troposphere and ionosphere delays for weather, climate, and natural hazard applications, to disturbances in the signals due to multipath reflections from the solid ground, water, and ice for environmental applications. We review the relevant concepts of geodetic theory, data analysis, and physical modeling for a myriad of processes at multiple spatial and temporal scales, and discuss the extensive global infrastructure that has been built to support GPS geodesy consisting of thousands of continuously operating stations. We also discuss the integration of heterogeneous and complementary data sets from geodesy, seismology, and geology, focusing on crustal deformation applications and early warning systems for natural hazards.

SLR and GPS spatial techniques in ITRF. Argentine results.

Science.gov (United States)

Actis, Eloy Vicente; Huang, Dongping; Márquez, Raúl; Adarvez, Sonia; Flores, Matías; Brizuela, Diego; Nievas, Jesica; Podestá, Ricardo; Pacheco, Ana M.; Rojas, Hernán Alvis; Yin, Zhiqiang; Li, Jinzeng; Han, Yanben; Liu, Weidong; Wang, Rui

2012-08-01

Along the late 30 years spatial geodetic techniques enable us to measure horizontal and vertical deformations of the Earth’s surface with a very high precision. Performing this task we made Satellite Laser Ranging (SLR), and Global Positioning System (GPS) observations in South America ILRS 7406 Station placed at Observatorio Astronómico Félix Aguilar (OAFA) in San Juan, Argentina, accomplishing a Cooperation Agreement between CAS - NAOC and OAFA - UNSJ. Trough LAGEOS II Satellite observations we obtain rectangular coordinates of San Juan ILRS Station in the Terrestrial Reference Frame (ITR 2000), standing out that Argentine Station data were included in the late arrangements ITRF given by International Earth Rotation and Reference System Service (IERS). Spatial and temporary variations of the epoch 2010 - 2011 were evaluated finding out remarkable displacements, of about a half meter, related with seismic events on the region. We confirm these deformations by means of GP S determinations referred to Permanent GPS Station placed nearby the SLR Station.

Precise Positioning of Uavs - Dealing with Challenging Rtk-Gps Measurement Conditions during Automated Uav Flights

Science.gov (United States)

Zimmermann, F.; Eling, C.; Klingbeil, L.; Kuhlmann, H.

2017-08-01

For some years now, UAVs (unmanned aerial vehicles) are commonly used for different mobile mapping applications, such as in the fields of surveying, mining or archeology. To improve the efficiency of these applications an automation of the flight as well as the processing of the collected data is currently aimed at. One precondition for an automated mapping with UAVs is that the georeferencing is performed directly with cm-accuracies or better. Usually, a cm-accurate direct positioning of UAVs is based on an onboard multi-sensor system, which consists of an RTK-capable (real-time kinematic) GPS (global positioning system) receiver and additional sensors (e.g. inertial sensors). In this case, the absolute positioning accuracy essentially depends on the local GPS measurement conditions. Especially during mobile mapping applications in urban areas, these conditions can be very challenging, due to a satellite shadowing, non-line-of sight receptions, signal diffraction or multipath effects. In this paper, two straightforward and easy to implement strategies will be described and analyzed, which improve the direct positioning accuracies for UAV-based mapping and surveying applications under challenging GPS measurement conditions. Based on a 3D model of the surrounding buildings and vegetation in the area of interest, a GPS geometry map is determined, which can be integrated in the flight planning process, to avoid GPS challenging environments as far as possible. If these challenging environments cannot be avoided, the GPS positioning solution is improved by using obstruction adaptive elevation masks, to mitigate systematic GPS errors in the RTK-GPS positioning. Simulations and results of field tests demonstrate the profit of both strategies.

Special Features in the Structure of Resonant Perturbations of Uncontrollable Objects of Glonass and GPS Navigating Systems. Influence on the Orbital Evolution

Science.gov (United States)

Tomilova, I. V.; Bordovitsyna, T. V.

2017-08-01

Results of investigation into the resonant structure of perturbations and long-term orbital evolution of space vehicles of GLONASS and GPS global navigating satellite systems (GNSS) under assumption that all of them have lost control on 08/01/2015 are presented. It is demonstrated that the majority of the examined objects are in the range of action of the secular resonances of various types. In addition, practically all satellites of the GPS system are within the scope of the 2:1 orbital resonance with rotation of the Earth. Results of the MEGNO analysis demonstrate that the motion of all objects of the GLONASS system during the 100-year period is regular, whereas the motion of the majority of objects of the GPS system is subject to chaotization.

GPS antenna designs

Science.gov (United States)

Laube, Samuel J. P.

1987-05-01

Application of the current GPS NAVSTAR system to civilian service requires that a right hand, circularly polarized, -160 dBW spread spectrum signal be received from an orbiting satellite, where the antenna environment is also moving. This presents a design challenge when inexpensive antennas are desired. The intent of this survey is to provide information on the antennas mentioned and to construct and test prototypes to determine whether the choice made by the industry, the quadrifilar helix, is the best. The helix antenna is currently the low cost standard for GPS. Prototype versions were constructed using 12 gauge wire and subminiature coaxial hardline. The constructed antennas were tested using a signal generator and a reference turnstile. A spectrum analyzer was used to measure the level of the received signal.

The use of the AOA TTR-4P GPS receiver in operation at the BIPM for real-time restitution of GPS time

Science.gov (United States)

Thomas, Claudine

1994-01-01

The Global Positioning System is an outstanding tool for the dissemination of time. Using mono-channel C/A-code GPS time receivers, the restitution of GPS time through the satellite constellation presents a peak-to-peak discrepancy of several tens of nanoseconds without SA but may be as high as several hundreds of nanoseconds with SA. As a consequence, civil users are more and more interested in implementing hardware and software methods for efficient restitution of GPS time, especially in the framework of the project of a real-time prediction of UTC (UTCp) which could be available in the form of time differences (UTCp - GPS time). Previous work, for improving the real-time restitution of GPS time with SA, to the level obtained without SA, focused on the implementation of a Kalman filter based on past data and updated at each new observation. An alternative solution relies upon the statistical features of the noise brought about by SA; it has already been shown that the SA noise is efficiently reduced by averaging data from numerous satellites observed simultaneously over a sufficiently long time. This method was successfully applied to data from a GPS time receiver, model AOA TTR-4P, connected to the cesium clock kept at the BIPM. This device, a multi-channel, dual frequency, P-code GPS time receiver, is one of the first TTR-4P units in operation in a civil laboratory. Preliminary comparative studies of this new equipment with conventional GPS time receivers are described in this paper. The results of an experimental restitution of GPS time, obtained in June 1993, are also detailed: 3 to 6 satellites were observed simultaneously with a sample interval of 15 s, an efficient smoothing of SA noise was realized by averaging data on all observed satellites over more than 1 hour. When the GPS system is complete in 1994, 8 satellites will be observable continuously from anywhere in the world and the same level of uncertainty will be obtained using a shorter averaging

Radiotracking large wilderness mammals: Integration of GPS and Argos technology

Science.gov (United States)

Schwartz, Charles C.; Arthur, Steve M.

1999-01-01

We tested 30 prototype global positioning system (GPS) radiocollars on brown bears (Ursus arctos) over a 3-year period on the Kenai Peninsula, Alaska. Collars were of 2 design types: GPS with an Argos (Argos Data collection and Location System) satellite uplink (n=19) and GPS unites where the data were stored on board (n=10) for retrieval at a later date. All units also contained a conventional VHF (very high frequency) transmitter and weighed 1.7 kg. GPS-Argos united obtained 10-82% of expected GPS fixes, and fix rate declined significantly (Pbears varied more and were lower than fix rates for stationary collars placed in various vegetation types, suggesting that the bear, terrain, and movement all influence both fix and uplink success rate. Application of this new technology to grizzly and brown bear research and comparisons to studies with moose (Alces alces) are discussed.

Real-Time Magnitude Characterization of Large Earthquakes Using the Predominant Period Derived From 1 Hz GPS Data

Science.gov (United States)

Psimoulis, Panos A.; Houlié, Nicolas; Behr, Yannik

2018-01-01

Earthquake early warning (EEW) systems' performance is driven by the trade-off between the need for a rapid alert and the accuracy of each solution. A challenge for many EEW systems has been the magnitude saturation for large events (MW > 7) and the resulting underestimation of seismic moment magnitude. In this study, we test the performance of high-rate (1 Hz) GPS, based on seven seismic events, to evaluate whether long-period ground motions can be measured well enough to infer reliably earthquake predominant periods. We show that high-rate GPS data allow the computation of a GPS-based predominant period (τg) to estimate lower bounds for the magnitude of earthquakes and distinguish between large (MW > 7) and great (MW > 8) events and thus extend the capability of EEW systems for larger events. It has also identified the impact of the different values of the smoothing factor α on the τg results and how the sampling rate and the computation process differentiate τg from the commonly used τp.

An economic analysis of disaggregation of space assets: Application to GPS

Science.gov (United States)

Hastings, Daniel E.; La Tour, Paul A.

2017-05-01

New ideas, technologies and architectural concepts are emerging with the potential to reshape the space enterprise. One of those new architectural concepts is the idea that rather than aggregating payloads onto large very high performance buses, space architectures should be disaggregated with smaller numbers of payloads (as small as one) per bus and the space capabilities spread across a correspondingly larger number of systems. The primary rationale is increased survivability and resilience. The concept of disaggregation is examined from an acquisition cost perspective. A mixed system dynamics and trade space exploration model is developed to look at long-term trends in the space acquisition business. The model is used to examine the question of how different disaggregated GPS architectures compare in cost to the well-known current GPS architecture. A generation-over-generation examination of policy choices is made possible through the application of soft systems modeling of experience and learning effects. The assumptions that are allowed to vary are: design lives, production quantities, non-recurring engineering and time between generations. The model shows that there is always a premium in the first generation to be paid to disaggregate the GPS payloads. However, it is possible to construct survivable architectures where the premium after two generations is relatively low.

Advancing Technology: GPS and GIS Outreach Training for Agricultural Producers

Science.gov (United States)

Flynn, Allison; Arnold, Shannon

2010-01-01

The use of the Global Positioning System (GPS) and Global Information Systems (GIS) has made significant impacts on agricultural production practices. However, constant changes in the technologies require continuing educational updates. The outreach program described here introduces the operation, use, and applications of GPS receivers and GIS…

Azimuth selection for sea level measurements using geodetic GPS receivers

Science.gov (United States)

Wang, Xiaolei; Zhang, Qin; Zhang, Shuangcheng

2018-03-01

Based on analysis of Global Positioning System (GPS) multipath signals recorded by a geodetic GPS receiver, GPS Reflectometry (GPS-R) has demonstrated unique advantages in relation to sea level monitoring. Founded on multipath reflectometry theory, sea level changes can be measured by GPS-R through spectral analysis of recorded signal-to-noise ratio data. However, prior to estimating multipath parameters, it is necessary to define azimuth and elevation angle mask to ensure the reflecting zones are on water. Here, a method is presented to address azimuth selection, a topic currently under active development in the field of GPS-R. Data from three test sites: the Kachemak Bay GPS site PBAY in Alaska (USA), Friday Harbor GPS site SC02 in the San Juan Islands (USA), and Brest Harbor GPS site BRST in Brest (France) are analyzed. These sites are located in different multipath environments, from a rural coastal area to a busy harbor, and they experience different tidal ranges. Estimates by the GPS tide gauges at azimuths selected by the presented method are compared with measurements from physical tide gauges and acceptable correspondence found for all three sites.

An Enhanced Error Model for EKF-Based Tightly-Coupled Integration of GPS and Land Vehicle's Motion Sensors.

Science.gov (United States)

Karamat, Tashfeen B; Atia, Mohamed M; Noureldin, Aboelmagd

2015-09-22

Reduced inertial sensor systems (RISS) have been introduced by many researchers as a low-cost, low-complexity sensor assembly that can be integrated with GPS to provide a robust integrated navigation system for land vehicles. In earlier works, the developed error models were simplified based on the assumption that the vehicle is mostly moving on a flat horizontal plane. Another limitation is the simplified estimation of the horizontal tilt angles, which is based on simple averaging of the accelerometers' measurements without modelling their errors or tilt angle errors. In this paper, a new error model is developed for RISS that accounts for the effect of tilt angle errors and the accelerometer's errors. Additionally, it also includes important terms in the system dynamic error model, which were ignored during the linearization process in earlier works. An augmented extended Kalman filter (EKF) is designed to incorporate tilt angle errors and transversal accelerometer errors. The new error model and the augmented EKF design are developed in a tightly-coupled RISS/GPS integrated navigation system. The proposed system was tested on real trajectories' data under degraded GPS environments, and the results were compared to earlier works on RISS/GPS systems. The findings demonstrated that the proposed enhanced system introduced significant improvements in navigational performance.

Ground-Based Global Navigation Satellite System (GNSS) GPS Broadcast Ephemeris Data (daily files) from NASA CDDIS

Data.gov (United States)

National Aeronautics and Space Administration — This dataset consists of ground-based Global Navigation Satellite System (GNSS) GPS Broadcast Ephemeris Data (daily files) from the NASA Crustal Dynamics Data...

Investigating the performance of neural network backpropagation algorithms for TEC estimations using South African GPS data

Science.gov (United States)

Habarulema, J. B.; McKinnell, L.-A.

2012-05-01

In this work, results obtained by investigating the application of different neural network backpropagation training algorithms are presented. This was done to assess the performance accuracy of each training algorithm in total electron content (TEC) estimations using identical datasets in models development and verification processes. Investigated training algorithms are standard backpropagation (SBP), backpropagation with weight delay (BPWD), backpropagation with momentum (BPM) term, backpropagation with chunkwise weight update (BPC) and backpropagation for batch (BPB) training. These five algorithms are inbuilt functions within the Stuttgart Neural Network Simulator (SNNS) and the main objective was to find out the training algorithm that generates the minimum error between the TEC derived from Global Positioning System (GPS) observations and the modelled TEC data. Another investigated algorithm is the MatLab based Levenberg-Marquardt backpropagation (L-MBP), which achieves convergence after the least number of iterations during training. In this paper, neural network (NN) models were developed using hourly TEC data (for 8 years: 2000-2007) derived from GPS observations over a receiver station located at Sutherland (SUTH) (32.38° S, 20.81° E), South Africa. Verification of the NN models for all algorithms considered was performed on both "seen" and "unseen" data. Hourly TEC values over SUTH for 2003 formed the "seen" dataset. The "unseen" dataset consisted of hourly TEC data for 2002 and 2008 over Cape Town (CPTN) (33.95° S, 18.47° E) and SUTH, respectively. The models' verification showed that all algorithms investigated provide comparable results statistically, but differ significantly in terms of time required to achieve convergence during input-output data training/learning. This paper therefore provides a guide to neural network users for choosing appropriate algorithms based on the availability of computation capabilities used for research.

GPS-Aided Video Tracking

Directory of Open Access Journals (Sweden)

Udo Feuerhake

2015-08-01

Full Text Available Tracking moving objects is both challenging and important for a large variety of applications. Different technologies based on the global positioning system (GPS and video or radio data are used to obtain the trajectories of the observed objects. However, in some use cases, they fail to provide sufficiently accurate, complete and correct data at the same time. In this work we present an approach for fusing GPS- and video-based tracking in order to exploit their individual advantages. In this way we aim to combine the reliability of GPS tracking with the high geometric accuracy of camera detection. For the fusion of the movement data provided by the different devices we use a hidden Markov model (HMM formulation and the Viterbi algorithm to extract the most probable trajectories. In three experiments, we show that our approach is able to deal with challenging situations like occlusions or objects which are temporarily outside the monitored area. The results show the desired increase in terms of accuracy, completeness and correctness.

On stochastic modeling of the modernized global positioning system (GPS) L2C signal

International Nuclear Information System (INIS)

Elsobeiey, Mohamed; El-Rabbany, Ahmed

2010-01-01

In order to take full advantage of the modernized GPS L2C signal, it is essential that its stochastic characteristics and code bias be rigorously determined. In this paper, long sessions of GPS measurements are used to study the stochastic characteristics of the modernized GPS L2C signal. As a byproduct, the stochastic characteristics of the legacy GPS signals, namely C/A and P2 codes, are also determined, which are used to verify the developed stochastic model of the modernized signal. The differential code biases between P2 and C2, DCB P2-C2 , are also estimated using the Bernese GPS software. It is shown that the developed models improved the precise point positioning (PPP) solution and convergence time

Multi-GNSS phase delay estimation and PPP ambiguity resolution: GPS, BDS, GLONASS, Galileo

Science.gov (United States)

Li, Xingxing; Li, Xin; Yuan, Yongqiang; Zhang, Keke; Zhang, Xiaohong; Wickert, Jens

2018-06-01

This paper focuses on the precise point positioning (PPP) ambiguity resolution (AR) using the observations acquired from four systems: GPS, BDS, GLONASS, and Galileo (GCRE). A GCRE four-system uncalibrated phase delay (UPD) estimation model and multi-GNSS undifferenced PPP AR method were developed in order to utilize the observations from all systems. For UPD estimation, the GCRE-combined PPP solutions of the globally distributed MGEX and IGS stations are performed to obtain four-system float ambiguities and then UPDs of GCRE satellites can be precisely estimated from these ambiguities. The quality of UPD products in terms of temporal stability and residual distributions is investigated for GPS, BDS, GLONASS, and Galileo satellites, respectively. The BDS satellite-induced code biases were corrected for GEO, IGSO, and MEO satellites before the UPD estimation. The UPD results of global and regional networks were also evaluated for Galileo and BDS, respectively. As a result of the frequency-division multiple-access strategy of GLONASS, the UPD estimation was performed using a network of homogeneous receivers including three commonly used GNSS receivers (TRIMBLE NETR9, JAVAD TRE_G3TH DELTA, and LEICA). Data recorded from 140 MGEX and IGS stations for a 30-day period in January in 2017 were used to validate the proposed GCRE UPD estimation and multi-GNSS dual-frequency PPP AR. Our results show that GCRE four-system PPP AR enables the fastest time to first fix (TTFF) solutions and the highest accuracy for all three coordinate components compared to the single and dual system. An average TTFF of 9.21 min with 7{°} cutoff elevation angle can be achieved for GCRE PPP AR, which is much shorter than that of GPS (18.07 min), GR (12.10 min), GE (15.36 min) and GC (13.21 min). With observations length of 10 min, the positioning accuracy of the GCRE fixed solution is 1.84, 1.11, and 1.53 cm, while the GPS-only result is 2.25, 1.29, and 9.73 cm for the east, north, and vertical

Accuracy of a 10 Hz GPS Unit in Measuring Shuttle Velocity Performed at Different Speeds and Distances (5 – 20 M

Directory of Open Access Journals (Sweden)

Beato Marco

2016-12-01

Full Text Available The aim of this study was to validate the accuracy of a 10 Hz GPS device (STATSports, Ireland by comparing the instantaneous values of velocity determined with this device with those determined by kinematic (video analysis (25 Hz. Ten male soccer players were required to perform shuttle runs (with 180° change of direction at three velocities (slow: 2.2 m·s-1; moderate: 3.2 m·s-1; high: maximal over four distances: 5, 10, 15 and 20 m. The experiments were video-recorded; the “point by point” values of speed recorded by the GPS device were manually downloaded and analysed in the same way as the “frame by frame” values of horizontal speed as obtained by video analysis. The obtained results indicated that shuttle distance was smaller in GPS than video analysis (p < 0.01. Shuttle velocity (shuttle distance/shuttle time was thus smaller in GPS than in video analysis (p < 0.001; the percentage difference (bias, % in shuttle velocity between methods was found to decrease with the distance covered (5 m: 9 ± 6%; 20 m: 3 ± 3%. The instantaneous values of speed were averaged; from these data and from data of shuttle time, the distance covered was recalculated; the error (criterion distance-recalculated distance was negligible for video data (0.04 ± 0.28 m whereas GPS data underestimated criterion distance (0.31 ± 0.55 m. In conclusion, the inaccuracy of this GPS unit in determining shuttle speed can be attributed to inaccuracy in determining the shuttle distance.

Design about position and display of GPS based on singlechip

Directory of Open Access Journals (Sweden)

WU Dongdong

2016-02-01

Full Text Available GPS is used in ships,vehicles,aircraft and other moving objects.GPS also has the important application in vehicle monitoring system.However,with the expansion of the specialized functions of GPS,its high cost makes so many ordinary consumers unbearable.This paper proposes a simple design of GPS based on singlechip.The design Improves the basic utility functions of system and adds the speed and mileage measurement.GPS module uses the differential technology to improve the positioning accuracy.Therefore,the navigation device is compact,easy to carry and of high precision positioning.Through getting the data of 3D coordinates from the observation point and the factor of position accuracy,the average of which is less than five,indicating that the position accuracy can be improved by differential technology to achieve the desired range.At last,the feasibility of this design is verified through the current data tested in the outdoors.

A new analytical method for the classification of time-location data obtained from the global positioning system (GPS).

Science.gov (United States)

Kim, Taehyun; Lee, Kiyoung; Yang, Wonho; Yu, Seung Do

2012-08-01

Although the global positioning system (GPS) has been suggested as an alternative way to determine time-location patterns, its use has been limited. The purpose of this study was to evaluate a new analytical method of classifying time-location data obtained by GPS. A field technician carried a GPS device while simulating various scripted activities and recorded all movements by the second in an activity diary. The GPS device recorded geological data once every 15 s. The daily monitoring was repeated 18 times. The time-location data obtained by the GPS were compared with the activity diary to determine selection criteria for the classification of the GPS data. The GPS data were classified into four microenvironments (residential indoors, other indoors, transit, and walking outdoors); the selection criteria used were used number of satellites (used-NSAT), speed, and distance from residence. The GPS data were classified as indoors when the used-NSAT was below 9. Data classified as indoors were further classified as residential indoors when the distance from the residence was less than 40 m; otherwise, they were classified as other indoors. Data classified as outdoors were further classified as being in transit when the speed exceeded 2.5 m s(-1); otherwise, they were classified as walking outdoors. The average simple percentage agreement between the time-location classifications and the activity diary was 84.3 ± 12.4%, and the kappa coefficient was 0.71. The average differences between the time diary and the GPS results were 1.6 ± 2.3 h for the time spent in residential indoors, 0.9 ± 1.7 h for the time spent in other indoors, 0.4 ± 0.4 h for the time spent in transit, and 0.8 ± 0.5 h for the time spent walking outdoors. This method can be used to determine time-activity patterns in exposure-science studies.

A Kalman Filter Implementation for Precision Improvement in Low-Cost GPS Positioning of Tractors

Science.gov (United States)

Gomez-Gil, Jaime; Ruiz-Gonzalez, Ruben; Alonso-Garcia, Sergio; Gomez-Gil, Francisco Javier

2013-01-01

Low-cost GPS receivers provide geodetic positioning information using the NMEA protocol, usually with eight digits for latitude and nine digits for longitude. When these geodetic coordinates are converted into Cartesian coordinates, the positions fit in a quantization grid of some decimeters in size, the dimensions of which vary depending on the point of the terrestrial surface. The aim of this study is to reduce the quantization errors of some low-cost GPS receivers by using a Kalman filter. Kinematic tractor model equations were employed to particularize the filter, which was tuned by applying Monte Carlo techniques to eighteen straight trajectories, to select the covariance matrices that produced the lowest Root Mean Square Error in these trajectories. Filter performance was tested by using straight tractor paths, which were either simulated or real trajectories acquired by a GPS receiver. The results show that the filter can reduce the quantization error in distance by around 43%. Moreover, it reduces the standard deviation of the heading by 75%. Data suggest that the proposed filter can satisfactorily preprocess the low-cost GPS receiver data when used in an assistance guidance GPS system for tractors. It could also be useful to smooth tractor GPS trajectories that are sharpened when the tractor moves over rough terrain. PMID:24217355

Arctic tides from GPS on sea ice

OpenAIRE

Kildegaard Rose, Stine; Skourup, Henriette; Forsberg, René

2012-01-01

The presence of sea-ice in the Arctic Ocean plays a significant role in the Arctic climate. Sea ice dampens the ocean tide amplitude with the result that global tidal models which use only astronomical data perform less accurately in the polar regions. This study presents a kinematic processing of Global Positioning System (GPS) buoys placed on sea-ice at five different sites north of Greenland for the study of sea level height and tidal analysis to improve tidal models in the Central Arctic....

Thermal structure of intense convective clouds derived from GPS radio occultations

DEFF Research Database (Denmark)

Biondi, Riccardo; Randel, W. J.; Ho, S. -P.

2012-01-01

Thermal structure associated with deep convective clouds is investigated using Global Positioning System (GPS) radio occultation measurements. GPS data are insensitive to the presence of clouds, and provide high vertical resolution and high accuracy measurements to identify associated temperature...... behavior. Deep convective systems are identified using International Satellite Cloud Climatology Project (ISCCP) satellite data, and cloud tops are accurately measured using Cloud-Aerosol Lidar with Orthogonal Polarization (CALIPSO) lidar observations; we focus on 53 cases of near-coincident GPS...

Thermal structure of intense convective clouds derived from GPS radio occultations

DEFF Research Database (Denmark)

Biondi, Riccardo; Randel, W. J.; Ho, S.-P.

2011-01-01

Thermal structure associated with deep convective clouds is investigated using Global Positioning System (GPS) radio occultation measurements. GPS data are insensitive to the presence of clouds, and provide high vertical resolution and high accuracy measurements to identify associated temperature...... behavior. Deep convective systems are identified using International Satellite Cloud Climatology Project (ISCCP) satellite data, and cloud tops are accurately measured using Cloud-Aerosol Lidar with Orthogonal Polarization (CALIPSO) lidar observations; we focus on 53 cases of near-coincident GPS...

Effects of Reentry Plasma Sheath on GPS Patch Antenna Polarization Property

Directory of Open Access Journals (Sweden)

L. Zhao

2013-01-01

Full Text Available A plasma sheath enveloping a reentry vehicle would affect performances of on-board antenna greatly, especially the navigation antennas. This paper studies the effects of reentry plasma sheath on a GPS right-hand circularly polarized (RHCP patch antenna polarization property during a typical reentry process. Utilizing the algorithm of finite integration technique, the polarization characteristic of a GPS antenna coated by a plasma sheath is obtained. Results show that the GPS RHCP patch antenna radiation pattern distortions as well as polarization deteriorations exist during the entire reentry process, and the worst polarization mismatch loss between a GPS antenna and RHCP GPS signal is nearly 3 dB. This paper also indicates that measures should be taken to alleviate the plasma sheath for maintaining the GPS communication during the reentry process.

Briefing Highlights Vulnerability of GPS to Adverse Space Weather

Science.gov (United States)

Balcerak, Ernie

2011-08-01

Through its effects on GPS and other technologies, space weather can affect a variety of industries, including agriculture, commercial air travel, and emergency response. Speakers focused on these topics at a 22 June briefing on Capitol Hill in Washington, D. C. Solar flares can produce radio bursts that directly interfere with GPS signals. Solar activity can also cause ionospheric disturbances that produce distortions and delays in GPS signals, degrading the accuracy of positioning and navigation systems.

LADOTD GPS technology management plan.

Science.gov (United States)

2012-02-01

Over many years, Global Positioning System (GPS) technology has been adopted by different sections within the Louisiana : Department of Transportation and Development (DOTD), with no uniform standards for accuracy, operation, hardware, or : software....

PRECISE POSITIONING OF UAVS – DEALING WITH CHALLENGING RTK-GPS MEASUREMENT CONDITIONS DURING AUTOMATED UAV FLIGHTS

Directory of Open Access Journals (Sweden)

F. Zimmermann

2017-08-01

Full Text Available For some years now, UAVs (unmanned aerial vehicles are commonly used for different mobile mapping applications, such as in the fields of surveying, mining or archeology. To improve the efficiency of these applications an automation of the flight as well as the processing of the collected data is currently aimed at. One precondition for an automated mapping with UAVs is that the georeferencing is performed directly with cm-accuracies or better. Usually, a cm-accurate direct positioning of UAVs is based on an onboard multi-sensor system, which consists of an RTK-capable (real-time kinematic GPS (global positioning system receiver and additional sensors (e.g. inertial sensors. In this case, the absolute positioning accuracy essentially depends on the local GPS measurement conditions. Especially during mobile mapping applications in urban areas, these conditions can be very challenging, due to a satellite shadowing, non-line-of sight receptions, signal diffraction or multipath effects. In this paper, two straightforward and easy to implement strategies will be described and analyzed, which improve the direct positioning accuracies for UAV-based mapping and surveying applications under challenging GPS measurement conditions. Based on a 3D model of the surrounding buildings and vegetation in the area of interest, a GPS geometry map is determined, which can be integrated in the flight planning process, to avoid GPS challenging environments as far as possible. If these challenging environments cannot be avoided, the GPS positioning solution is improved by using obstruction adaptive elevation masks, to mitigate systematic GPS errors in the RTK-GPS positioning. Simulations and results of field tests demonstrate the profit of both strategies.

GPS surveying method applied to terminal area navigation flight experiments

Energy Technology Data Exchange (ETDEWEB)

Murata, M; Shingu, H; Satsushima, K; Tsuji, T; Ishikawa, K; Miyazawa, Y; Uchida, T [National Aerospace Laboratory, Tokyo (Japan)

1993-03-01

With an objective of evaluating accuracy of new landing and navigation systems such as microwave landing guidance system and global positioning satellite (GPS) system, flight experiments are being carried out using experimental aircraft. This aircraft mounts a GPS and evaluates its accuracy by comparing the standard orbits spotted by a Kalman filter from the laser tracing data on the aircraft with the navigation results. The GPS outputs position and speed information from an earth-centered-earth-fixed system called the World Geodetic System, 1984 (WGS84). However, in order to compare the navigation results with output from a reference orbit sensor or other navigation sensor, it is necessary to structure a high-precision reference coordinates system based on the WGS84. A method that applies the GPS phase interference measurement for this problem was proposed, and used actually in analyzing a flight experiment data. As referred to a case of the method having been applied to evaluating an independent navigation accuracy, the method was verified sufficiently effective and reliable not only in navigation method analysis, but also in the aspect of navigational operations. 12 refs., 10 figs., 5 tabs.

An ultra-wide bandwidth-based range/GPS tight integration approach for relative positioning in vehicular ad hoc networks

International Nuclear Information System (INIS)

Shen, Feng; Cheong, Joon Wayn; Dempster, Andrew G

2015-01-01

Relative position awareness is a vital premise for the implementation of emerging intelligent transportation systems, such as collision warning. However, commercial global navigation satellite systems (GNSS) receivers do not satisfy the requirements of these applications. Fortunately, cooperative positioning (CP) techniques, through sharing the GNSS measurements between vehicles, can improve the performance of relative positioning in a vehicular ad hoc network (VANET). In this paper, while assuming there are no obstacles between vehicles, a new enhanced tightly coupled CP technique is presented by adding ultra-wide bandwidth (UWB)-based inter-vehicular range measurements. In the proposed CP method, each vehicle fuses the GPS measurements and the inter-vehicular range measurements. Based on analytical and experimental results, in the full GPS coverage environment, the new tight integration CP method outperforms the INS-aided tight CP method, tight CP method, and DGPS by 11%, 15%, and 24%, respectively; in the GPS outage scenario, the performance improvement achieves 60%, 65%, and 73%, respectively. (paper)

An Enhanced Error Model for EKF-Based Tightly-Coupled Integration of GPS and Land Vehicle’s Motion Sensors

Science.gov (United States)

Karamat, Tashfeen B.; Atia, Mohamed M.; Noureldin, Aboelmagd

2015-01-01

Reduced inertial sensor systems (RISS) have been introduced by many researchers as a low-cost, low-complexity sensor assembly that can be integrated with GPS to provide a robust integrated navigation system for land vehicles. In earlier works, the developed error models were simplified based on the assumption that the vehicle is mostly moving on a flat horizontal plane. Another limitation is the simplified estimation of the horizontal tilt angles, which is based on simple averaging of the accelerometers’ measurements without modelling their errors or tilt angle errors. In this paper, a new error model is developed for RISS that accounts for the effect of tilt angle errors and the accelerometer’s errors. Additionally, it also includes important terms in the system dynamic error model, which were ignored during the linearization process in earlier works. An augmented extended Kalman filter (EKF) is designed to incorporate tilt angle errors and transversal accelerometer errors. The new error model and the augmented EKF design are developed in a tightly-coupled RISS/GPS integrated navigation system. The proposed system was tested on real trajectories’ data under degraded GPS environments, and the results were compared to earlier works on RISS/GPS systems. The findings demonstrated that the proposed enhanced system introduced significant improvements in navigational performance. PMID:26402680

Seasonal and circadian biases in bird tracking with solar GPS-tags

OpenAIRE

Silva, Rafa; Afán, Isabel; Gil, Juan A.; Bustamante, Javier

2017-01-01

Global Positioning System (GPS) tags are nowadays widely used in wildlife tracking. This geolocation technique can suffer from fix loss biases due to poor satellite GPS geometry, that result in tracking data gaps leading to wrong research conclusions. In addition, new solar-powered GPS tags deployed on birds can suffer from a new "battery drain bias" currently ignored in movement ecology analyses. We use a GPS tracking dataset of bearded vultures (Gypaetus barbatus), tracked for several years...

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

Science.gov (United States)

Zou, Rong; Wang, Qi; Freymueller, Jeffrey T; Poutanen, Markku; Cao, Xuelian; Zhang, Caihong; Yang, Shaomin; He, Ping

2015-12-04

In southern Tibet, ongoing vertical and horizontal motions due to the collision between India and Eurasia are monitored by large numbers of global positioning system (GPS) continuous and campaign sites installed in the past decade. Displacements measured by GPS usually include tectonic deformation as well as non-tectonic, time-dependent signals. To estimate the regional long-term tectonic deformation using GPS more precisely, seasonal elastic deformation signals associated with surface loading must be removed from the observations. In this study, we focus on seasonal variation in vertical and horizontal motions of southern Tibet by performing a joint analysis of GRACE (Gravity Recovery and Climate Experiment) and GPS data, not only using continuous sites but also GPS campaign-mode sites. We found that the GPS-observed and GRACE-modeled seasonal oscillations are in good agreements, and a seasonal displacement model demonstrates that the main reason for seasonal variations in southern Tibet is from the summer monsoon and its precipitation. The biggest loading appears from July to August in the summer season. Vertical deformations observed by GPS and modeled by GRACE are two to three times larger than horizontal oscillations, and the north components demonstrate larger amplitudes than the east components. We corrected the GPS position time series using the GRACE-modeled seasonal variations, which gives significant reductions in the misfit and weighted root-mean-squares (WRMS). Misfit (χ2 divided by degree of freedom) reductions for campaign sites range between 20% and 56% for the vertical component, and are much smaller for the horizontal components. Moreover, time series of continuous GPS (cGPS) sites near the 2015 Nepal earthquakes must be corrected using appropriate models of seasonal loading for analyzing postseismic deformation to avoid biasing estimates of the postseismic relaxation.

GPS phase scintillation during the geomagnetic storm of March 17, 2015: The relation to auroral electrojet currents

DEFF Research Database (Denmark)

Prikryl, Paul; Ghoddousi-Fard, Reza; Connors, Martin

and magnetometers. GPS phase scintillation index is computed for L1 signal sampled at the rate of 50 Hz by specialized GPS scintillation receivers of the Expanded Canadian High Arctic Ionospheric Network (ECHAIN). To further extend the geographic coverage, the phasescintillation proxy index is obtained from......Ionospheric irregularities cause rapid fluctuations of radio wave amplitude and phase that candegrade GPS positional accuracy and affect performance of radio communication and navigation systems. The ionosphere becomes particularly disturbed during geomagnetic storms caused by impacts of coronal...... mass ejections compounded by high-speed plasma streams from coronal holes. Geomagnetic storm of March 17, 2015 was the largest in the current solar cycle. The high-latitude ionosphere dynamics is studied using arrays of ground-based instruments including GPS receivers, HF radars, ionosondes, riometers...

Routing Unmanned Vehicles in GPS-Denied Environments

OpenAIRE

Sundar, Kaarthik; Misra, Sohum; Rathinam, Sivakumar; Sharma, Rajnikant

2017-01-01

Most of the routing algorithms for unmanned vehicles, that arise in data gathering and monitoring applications in the literature, rely on the Global Positioning System (GPS) information for localization. However, disruption of GPS signals either intentionally or unintentionally could potentially render these algorithms not applicable. In this article, we present a novel method to address this difficulty by combining methods from cooperative localization and routing. In particular, the article...

A Study on Remote On-Line Diagnostic System for Vehicles by Integrating the Technology of OBD, GPS, and 3G

OpenAIRE

Jyong Lin; Shih-Chang Chen; Yu-Tsen Shih; Shi-Huang Chen

2009-01-01

This paper presents a remote on-line diagnostic system for vehicles via the use of On-Board Diagnostic (OBD), GPS, and 3G techniques. The main parts of the proposed system are on-board computer, vehicle monitor server, and vehicle status browser. First, the on-board computer can obtain the location of deriver and vehicle status from GPS receiver and OBD interface, respectively. Then on-board computer will connect with the vehicle monitor server through 3G network to trans...

Using GPS to Detect Imminent Tsunamis

Science.gov (United States)

Song, Y. Tony

2009-01-01

A promising method of detecting imminent tsunamis and estimating their destructive potential involves the use of Global Positioning System (GPS) data in addition to seismic data. Application of the method is expected to increase the reliability of global tsunami-warning systems, making it possible to save lives while reducing the incidence of false alarms. Tsunamis kill people every year. The 2004 Indian Ocean tsunami killed about 230,000 people. The magnitude of an earthquake is not always a reliable indication of the destructive potential of a tsunami. The 2004 Indian Ocean quake generated a huge tsunami, while the 2005 Nias (Indonesia) quake did not, even though both were initially estimated to be of the similar magnitude. Between 2005 and 2007, five false tsunami alarms were issued worldwide. Such alarms result in negative societal and economic effects. GPS stations can detect ground motions of earthquakes in real time, as frequently as every few seconds. In the present method, the epicenter of an earthquake is located by use of data from seismometers, then data from coastal GPS stations near the epicenter are used to infer sea-floor displacements that precede a tsunami. The displacement data are used in conjunction with local topographical data and an advanced theory to quantify the destructive potential of a tsunami on a new tsunami scale, based on the GPS-derived tsunami energy, much like the Richter Scale used for earthquakes. An important element of the derivation of the advanced theory was recognition that horizontal sea-floor motions contribute much more to generation of tsunamis than previously believed. The method produces a reliable estimate of the destructive potential of a tsunami within minutes typically, well before the tsunami reaches coastal areas. The viability of the method was demonstrated in computational tests in which the method yielded accurate representations of three historical tsunamis for which well-documented ground

Road Traffic Anomaly Detection via Collaborative Path Inference from GPS Snippets

Directory of Open Access Journals (Sweden)

Hongtao Wang

2017-03-01

Full Text Available Road traffic anomaly denotes a road segment that is anomalous in terms of traffic flow of vehicles. Detecting road traffic anomalies from GPS (Global Position System snippets data is becoming critical in urban computing since they often suggest underlying events. However, the noisy ands parse nature of GPS snippets data have ushered multiple problems, which have prompted the detection of road traffic anomalies to be very challenging. To address these issues, we propose a two-stage solution which consists of two components: a Collaborative Path Inference (CPI model and a Road Anomaly Test (RAT model. CPI model performs path inference incorporating both static and dynamic features into a Conditional Random Field (CRF. Dynamic context features are learned collaboratively from large GPS snippets via a tensor decomposition technique. Then RAT calculates the anomalous degree for each road segment from the inferred fine-grained trajectories in given time intervals. We evaluated our method using a large scale real world dataset, which includes one-month GPS location data from more than eight thousand taxi cabs in Beijing. The evaluation results show the advantages of our method beyond other baseline techniques.

Improved GPS-based Satellite Relative Navigation Using Femtosecond Laser Relative Distance Measurements

Directory of Open Access Journals (Sweden)

Hyungjik Oh

2016-03-01

Full Text Available This study developed an approach for improving Carrier-phase Differential Global Positioning System (CDGPS based realtime satellite relative navigation by applying laser baseline measurement data. The robustness against the space operational environment was considered, and a Synthetic Wavelength Interferometer (SWI algorithm based on a femtosecond laser measurement model was developed. The phase differences between two laser wavelengths were combined to measure precise distance. Generated laser data were used to improve estimation accuracy for the float ambiguity of CDGPS data. Relative navigation simulations in real-time were performed using the extended Kalman filter algorithm. The GPS and laser-combined relative navigation accuracy was compared with GPS-only relative navigation solutions to determine the impact of laser data on relative navigation. In numerical simulations, the success rate of integer ambiguity resolution increased when laser data was added to GPS data. The relative navigational errors also improved five-fold and two-fold, relative to the GPS-only error, for 250 m and 5 km initial relative distances, respectively. The methodology developed in this study is suitable for application to future satellite formation-flying missions.

Backyard Botany: Using GPS Technology in the Science Classroom

Science.gov (United States)

March, Kathryn A.

2012-01-01

Global Positioning System (GPS) technology can be used to connect students to the natural world and improve their skills in observation, identification, and classification. Using GPS devices in the classroom increases student interest in science, encourages team-building skills, and improves biology content knowledge. Additionally, it helps…

Radio-tracking large wilderness mammals: integration of GPS and Argos technologies

Science.gov (United States)

Schwartz, Charles C.; Arthur, Steve M.

1999-01-01

We tested 30 prototype global positioning system (GPS) radiocollars on brown bears (Ursus arctos) over a 3-year period on the Kenai Peninsula, Alaska. Collars were of 2 design types: GPS units with an Argos (Argos Data collection and Location System) satellite uplink (n = 19) and GPS units where the data were stored on board (n = 10) for retrieval at a later date. All units also contained a conventional VHF (very high frequency) transmitter and weighed 1.7 kg. GPS-Argos units obtained 10-82% of expected GPS fixes, and fix rate declined significantly (P bears varied more and were lower than fix rates for stationary collars placed in various vegetation types, suggesting that the bear, terrain, and movement all influence both fix and uplink success rate. Application of this new technology to grizzly and brown bear research and comparisons to studies with moose (Alces alces) are discussed.

The covariance of GPS coordinates and frames

International Nuclear Information System (INIS)

Lachieze-Rey, Marc

2006-01-01

We explore, in the general relativistic context, the properties of the recently introduced global positioning system (GPS) coordinates, as well as those of the associated frames and coframes that they define. We show that they are covariant and completely independent of any observer. We show that standard spectroscopic and astrometric observations allow any observer to measure (i) the values of the GPS coordinates at his position (ii) the components of his 4-velocity and (iii) the components of the metric in the GPS frame. This provides this system with a unique value both for conceptual discussion (no frame dependence) and for practical use (involved quantities are directly measurable): localization, motion monitoring, astrometry, cosmography and tests of gravitation theories. We show explicitly, in the general relativistic context, how an observer may estimate his position and motion, and reconstruct the components of the metric. This arises from two main results: the extension of the velocity fields of the probes to the whole (curved) spacetime, and the identification of the components of the observer's velocity in the GPS frame with the (inversed) observed redshifts of the probes. Specific cases (non-relativistic velocities, Minkowski and Friedmann-Lemaitre spacetimes, geodesic motions) are studied in detail

Precision GPS orbit determination strategies for an earth orbiter and geodetic tracking system

Science.gov (United States)

Lichten, Stephen M.; Bertiger, Willy I.; Border, James S.

1988-01-01

Data from two 1985 GPS field tests were processed and precise GPS orbits were determined. With a combined carrier phase and pseudorange, the 1314-km repeatability improves substantially to 5 parts in 10 to the 9th (0.6 cm) in the north and 2 parts in 10 to the 8th (2-3 cm) in the other components. To achieve these levels of repeatability and accuracy, it is necessary to fine-tune the GPS solar radiation coefficients and ground station zenith tropospheric delays.

Global Positioning System (GPS) Receiver Design For Multipaths Mitigation

National Research Council Canada - National Science Library

Gadallah, El-Sayed

1998-01-01

.... This research introduces a new estimator that can detect the presence of multipath, can determine the unknown number of multipath components and can estimate multipath parameters in the GPS receiver...

Challenges and advantages of using GPS data in outdoor advertisement

OpenAIRE

Hecker, Dirk; Körner, Christine; May, Michael

2011-01-01

A growing number of companies use mobility data in their day-to-day business. Especially in the area of outdoor advertising, GPS devices have been successfully applied in order to measure poster performance in recent years. Based on personal mobility traces, the quality and precision of performance measures has increased significantly. However, the usage of GPS technology poses several challenges when applied to critical business processes. We will present several challenges and solutions whi...

Differential GNSS and Vision-Based Tracking to Improve Navigation Performance in Cooperative Multi-UAV Systems

Directory of Open Access Journals (Sweden)

Amedeo Rodi Vetrella

2016-12-01

Full Text Available Autonomous navigation of micro-UAVs is typically based on the integration of low cost Global Navigation Satellite System (GNSS receivers and Micro-Electro-Mechanical Systems (MEMS-based inertial and magnetic sensors to stabilize and control the flight. The resulting navigation performance in terms of position and attitude accuracy may not suffice for other mission needs, such as the ones relevant to fine sensor pointing. In this framework, this paper presents a cooperative UAV navigation algorithm that allows a chief vehicle, equipped with inertial and magnetic sensors, a Global Positioning System (GPS receiver, and a vision system, to improve its navigation performance (in real time or in the post processing phase exploiting formation flying deputy vehicles equipped with GPS receivers. The focus is set on outdoor environments and the key concept is to exploit differential GPS among vehicles and vision-based tracking (DGPS/Vision to build a virtual additional navigation sensor whose information is then integrated in a sensor fusion algorithm based on an Extended Kalman Filter. The developed concept and processing architecture are described, with a focus on DGPS/Vision attitude determination algorithm. Performance assessment is carried out on the basis of both numerical simulations and flight tests. In the latter ones, navigation estimates derived from the DGPS/Vision approach are compared with those provided by the onboard autopilot system of a customized quadrotor. The analysis shows the potential of the developed approach, mainly deriving from the possibility to exploit magnetic- and inertial-independent accurate attitude information.

Application of Cyclostationary Signal Selectivity to the Carry-On Multi-Platform GPS Assisted Time Difference of Arrival System

National Research Council Canada - National Science Library

Streight, David

1997-01-01

.... The Applied Research Lab at the University of Texas at Austin (ARL:UT) has developed a prototype TDOA system, the Carry-on Multi-platform GPS Assisted Time Difference of Arrival System for the Naval Information Warfare Activity...

GPS-based household interview survey for the Cincinnati, Ohio Region.

Science.gov (United States)

2012-02-01

Methods for Conducting a Large-Scale GPS-Only Survey of Households: Past Household Travel Surveys (HTS) in the United States have only piloted small subsamples of Global Positioning Systems (GPS) completes compared with 1-2 day self-reported travel i...

Using Map Service API for Driving Cycle Detection for Wearable GPS Data: Preprint

Energy Technology Data Exchange (ETDEWEB)

Zhu, Lei [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Gonder, Jeffrey D [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2017-12-06

Following advancements in smartphone and portable global positioning system (GPS) data collection, wearable GPS data have realized extensive use in transportation surveys and studies. The task of detecting driving cycles (driving or car-mode trajectory segments) from wearable GPS data has been the subject of much research. Specifically, distinguishing driving cycles from other motorized trips (such as taking a bus) is the main research problem in this paper. Many mode detection methods only focus on raw GPS speed data while some studies apply additional information, such as geographic information system (GIS) data, to obtain better detection performance. Procuring and maintaining dedicated road GIS data are costly and not trivial, whereas the technical maturity and broad use of map service application program interface (API) queries offers opportunities for mode detection tasks. The proposed driving cycle detection method takes advantage of map service APIs to obtain high-quality car-mode API route information and uses a trajectory segmentation algorithm to find the best-matched API route. The car-mode API route data combined with the actual route information, including the actual mode information, are used to train a logistic regression machine learning model, which estimates car modes and non-car modes with probability rates. The experimental results show promise for the proposed method's ability to detect vehicle mode accurately.

TLALOCNet continuous GPS-Met Array in Mexico supporting the 2017 NAM GPS Hydrometeorological Network.

Science.gov (United States)

Cabral-Cano, E.; Salazar-Tlaczani, L.; Adams, D. K.; Vivoni, E. R.; Grutter, M.; Serra, Y. L.; DeMets, C.; Galetzka, J.; Feaux, K.; Mattioli, G. S.; Miller, M. M.

2017-12-01

TLALOCNet is a network of continuous GPS and meteorology stations in Mexico to study atmospheric and solid earth processes. This recently completed network spans most of Mexico with a strong coverage emphasis on southern and western Mexico. This network, funded by NSF, CONACyT and UNAM, recently built 40 cGPS-Met sites to EarthScope Plate Boundary Observatory standards and upgraded 25 additional GPS stations. TLALOCNet provides open and freely available raw GPS data, and high frequency surface meteorology measurements, and time series of daily positions. This is accomplished through the development of the TLALOCNet data center (http://tlalocnet.udg.mx) that serves as a collection and distribution point. This data center is based on UNAVCO's Dataworks-GSAC software and also works as part of UNAVCO's seamless archive for discovery, sharing, and access to GPS data. The TLALOCNet data center also contains contributed data from several regional GPS networks in Mexico for a total of 100+ stations. By using the same protocols and structure as the UNAVCO and other COCONet regional data centers, the scientific community has the capability of accessing data from the largest Mexican GPS network. This archive provides a fully queryable and scriptable GPS and Meteorological data retrieval point. In addition, real-time 1Hz streams from selected TLALOCNet stations are available in BINEX, RTCM 2.3 and RTCM 3.1 formats via the Networked Transport of RTCM via Internet Protocol (NTRIP) for real-time seismic and weather forecasting applications. TLALOCNet served as a GPS-Met backbone for the binational Mexico-US North American Monsoon GPS Hydrometeorological Network 2017 campaign experiment. This innovative experiment attempts to address water vapor source regions and land-surface water vapor flux contributions to precipitation (i.e., moisture recycling) during the 2017 North American Monsoon in Baja California, Sonora, Chihuahua, and Arizona. Models suggest that moisture recycling is

Integrating GIS and GPS in environmental remediation oversight

International Nuclear Information System (INIS)

Kaletsky, K.; Earle, J.R.; Schneider, T.A.

1996-01-01

This paper presents findings on Ohio EPA Office of Federal Facilities Oversight's (OFFO) use of GIS and GPS for environmental remediation oversight at the U.S. Department of Energy's (DOE) Fernald Site. The Fernald site is a former uranium metal production facility within DOE's nuclear weapons complex. Significant uranium contamination of soil and groundwater is being remediated under state and federal regulations. OFFO uses GIS/GPS to enhance environmental monitoring and remediation oversight. These technologies are utilized within OFFO's environmental monitoring program for sample location and parameter selection, data interpretation and presentation. GPS is used to integrate sample data into OFFO's GIS and for permanently linking precise and accurate geographic data to samples and waste units. It is important to identify contamination geographically as all visual references (e.g., buildings, infrastructure) will be removed during remediation. Availability of the GIS allows OFFO to perform independent analysis and review of DOE contractor generated data, models, maps, and designs. This ability helps alleviate concerns associated with open-quotes black boxclose quotes models and data interpretation. OFFO's independent analysis has increased regulatory confidence and the efficiency of design reviews. GIS/GPS technology allows OFFO to record and present complex data in a visual format aiding in stakeholder education and awareness. Presented are OFFO's achievements within the aforementioned activities and some reasons learned in implementing the GIS/GPS program. OFFO's two years of GIS/GPS development have resulted in numerous lessons learned and ideas for increasing effectiveness through the use of GIS/GPS

Global Positioning System (GPS) Receiver Autonomous Integrity Monitoring (RAIM) web service to support Area Navigation (RNAV) flight planning

Science.gov (United States)

2008-01-28

The Volpe Center designed, implemented, and deployed a Global Positioning System (GPS) Receiver Autonomous Integrity Monitoring (RAIM) prediction system in the mid 1990s to support both Air Force and Federal Aviation Administration (FAA) use of TSO C...

GNSS global real-time augmentation positioning: Real-time precise satellite clock estimation, prototype system construction and performance analysis

Science.gov (United States)

Chen, Liang; Zhao, Qile; Hu, Zhigang; Jiang, Xinyuan; Geng, Changjiang; Ge, Maorong; Shi, Chuang

2018-01-01

Lots of ambiguities in un-differenced (UD) model lead to lower calculation efficiency, which isn't appropriate for the high-frequency real-time GNSS clock estimation, like 1 Hz. Mixed differenced model fusing UD pseudo-range and epoch-differenced (ED) phase observations has been introduced into real-time clock estimation. In this contribution, we extend the mixed differenced model for realizing multi-GNSS real-time clock high-frequency updating and a rigorous comparison and analysis on same conditions are performed to achieve the best real-time clock estimation performance taking the efficiency, accuracy, consistency and reliability into consideration. Based on the multi-GNSS real-time data streams provided by multi-GNSS Experiment (MGEX) and Wuhan University, GPS + BeiDou + Galileo global real-time augmentation positioning prototype system is designed and constructed, including real-time precise orbit determination, real-time precise clock estimation, real-time Precise Point Positioning (RT-PPP) and real-time Standard Point Positioning (RT-SPP). The statistical analysis of the 6 h-predicted real-time orbits shows that the root mean square (RMS) in radial direction is about 1-5 cm for GPS, Beidou MEO and Galileo satellites and about 10 cm for Beidou GEO and IGSO satellites. Using the mixed differenced estimation model, the prototype system can realize high-efficient real-time satellite absolute clock estimation with no constant clock-bias and can be used for high-frequency augmentation message updating (such as 1 Hz). The real-time augmentation message signal-in-space ranging error (SISRE), a comprehensive accuracy of orbit and clock and effecting the users' actual positioning performance, is introduced to evaluate and analyze the performance of GPS + BeiDou + Galileo global real-time augmentation positioning system. The statistical analysis of real-time augmentation message SISRE is about 4-7 cm for GPS, whlile 10 cm for Beidou IGSO/MEO, Galileo and about 30 cm

A Java-based tool for creating KML files from GPS waypoints

Science.gov (United States)

Kinnicutt, P. G.; Rivard, C.; Rimer, S.

2008-12-01

Google Earth provides a free tool with powerful capabilities for visualizing geoscience images and data. Commercial software tools exist for doing sophisticated digitizing and spatial modeling , but for the purposes of presentation, visualization and overlaying aerial images with data Google Earth provides much of the functionality. Likewise, with current technologies in GPS (Global Positioning System) systems and with Google Earth Plus, it is possible to upload GPS waypoints, tracks and routes directly into Google Earth for visualization. However, older technology GPS units and even low-cost GPS units found today may lack the necessary communications interface to a computer (e.g. no Bluetooth, no WiFi, no USB, no Serial, etc.) or may have an incompatible interface, such as a Serial port but no USB adapter available. In such cases, any waypoints, tracks and routes saved in the GPS unit or recorded in a field notebook must be manually transferred to a computer for use in a GIS system or other program. This presentation describes a Java-based tool developed by the author which enables users to enter GPS coordinates in a user-friendly manner, then save these coordinates in a Keyhole MarkUp Language (KML) file format, for visualization in Google Earth. This tool either accepts user-interactive input or accepts input from a CSV (Comma Separated Value) file, which can be generated from any spreadsheet program. This tool accepts input in the form of lat/long or UTM (Universal Transverse Mercator) coordinates. This presentation describes this system's applicability through several small case studies. This free and lightweight tool simplifies the task of manually inputting GPS data into Google Earth for people working in the field without an automated mechanism for uploading the data; for instance, the user may not have internet connectivity or may not have the proper hardware or software. Since it is a Java application and not a web- based tool, it can be installed on one

GPS sledovací systém

OpenAIRE

Hofman, Jan

2010-01-01

V práci je popsán základní princip a vlastnosti globálního pozičního systému GPS. Je zde přiblížena problematika určování polohy, rychlosti a nadmořské výšky. Tyto poznatky jsou dále použity pro návrh zařízení, které komunikuje s běžně vyráběným GPS přijímačem a z něj získané informace zpracovává a ukládá do paměti pro pozdější vyhodnocení The keystone and properties of Global Position System (GPS) are described in this thesis. The thesis explains questions of position, speed and elevation...

Efficient GPS Position Determination Algorithms

National Research Council Canada - National Science Library

Nguyen, Thao Q

2007-01-01

... differential GPS algorithm for a network of users. The stand-alone user GPS algorithm is a direct, closed-form, and efficient new position determination algorithm that exploits the closed-form solution of the GPS trilateration equations and works...

Coarse Initial Orbit Determination for a Geostationary Satellite Using Single-Epoch GPS Measurements

Directory of Open Access Journals (Sweden)

Ghangho Kim

2015-04-01

Full Text Available A practical algorithm is proposed for determining the orbit of a geostationary orbit (GEO satellite using single-epoch measurements from a Global Positioning System (GPS receiver under the sparse visibility of the GPS satellites. The algorithm uses three components of a state vector to determine the satellite’s state, even when it is impossible to apply the classical single-point solutions (SPS. Through consideration of the characteristics of the GEO orbital elements and GPS measurements, the components of the state vector are reduced to three. However, the algorithm remains sufficiently accurate for a GEO satellite. The developed algorithm was tested on simulated measurements from two or three GPS satellites, and the calculated maximum position error was found to be less than approximately 40 km or even several kilometers within the geometric range, even when the classical SPS solution was unattainable. In addition, extended Kalman filter (EKF tests of a GEO satellite with the estimated initial state were performed to validate the algorithm. In the EKF, a reliable dynamic model was adapted to reduce the probability of divergence that can be caused by large errors in the initial state.

Coarse Initial Orbit Determination for a Geostationary Satellite Using Single-Epoch GPS Measurements

Science.gov (United States)

Kim, Ghangho; Kim, Chongwon; Kee, Changdon

2015-01-01

A practical algorithm is proposed for determining the orbit of a geostationary orbit (GEO) satellite using single-epoch measurements from a Global Positioning System (GPS) receiver under the sparse visibility of the GPS satellites. The algorithm uses three components of a state vector to determine the satellite’s state, even when it is impossible to apply the classical single-point solutions (SPS). Through consideration of the characteristics of the GEO orbital elements and GPS measurements, the components of the state vector are reduced to three. However, the algorithm remains sufficiently accurate for a GEO satellite. The developed algorithm was tested on simulated measurements from two or three GPS satellites, and the calculated maximum position error was found to be less than approximately 40 km or even several kilometers within the geometric range, even when the classical SPS solution was unattainable. In addition, extended Kalman filter (EKF) tests of a GEO satellite with the estimated initial state were performed to validate the algorithm. In the EKF, a reliable dynamic model was adapted to reduce the probability of divergence that can be caused by large errors in the initial state. PMID:25835299

An Extended ADOP for Performance Evaluation of Single-Frequency Single-Epoch Positioning by BDS/GPS in Asia-Pacific Region

Directory of Open Access Journals (Sweden)

Xin Liu

2017-09-01

Full Text Available Single-Frequency Single-Epoch (SFSE high-precision positioning has always been the hot spot of Global Navigation Satellite System (GNSS, and ambiguity dilution of precision (ADOP is a well-known scalar measure for success rate of ambiguity resolution. Traditional ADOP expression is complicated, thus the SFSE extended ADOP (E-ADOP, with the newly defined Summation-Multiplication Ratio of Weight (SMRW and two theorems for short baseline, was developed. This simplifies the ADOP expression; gives a clearer insight into the influences of SMRW and number of satellites on E-ADOP; and makes theoretical analysis of E-ADOP more convenient than that of ADOP, and through that the E-ADOP value can be predicted more accurately than through the ADOP expression for ADOP value. E-ADOP reveals that number of satellites and SMRW or high-elevation satellite are important for ADOP and, through E-ADOP, we studied which factor is dominant to control ADOP in different conditions and make ADOP different between BeiDou Navigation Satellite System (BDS, Global Positioning System (GPS, and BDS/GPS. Based on experimental results of SFSE positioning with different baselines, some conclusions are made: (1 ADOP decreases when new satellites are added mainly because the number of satellites becomes larger; (2 when the number of satellites is constant, ADOP is mainly affected by SMRW; (3 in contrast to systems where the satellites with low-elevation are the majority or where low- and high-elevation satellites are equally distributed, in systems where the high-elevation satellites are the majority, the SMRW mainly makes ADOP smaller, even if there are fewer satellites than in the two previous cases, and the difference in numbers of satellites can be expanded as the proportion of high-elevation satellites becomes larger; and (4 ADOP of BDS is smaller than ADOP of GPS mainly because of its SMRW.

GPS Civil Monitoring Performance Specification

Science.gov (United States)

2009-02-10

This Civil Monitoring Performance Specification (CMPS) is published and maintained at : the direction of the Program Manager for Civil Applications, Global Positioning Systems : Wing (GPSW). The purpose of this document is to provide a comprehensive ...

Development of position measuring technology by GPS; GPS ni yoru sokui gijutsu no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

Ishizaki, T [Ministry of Transportation, Tokyo (Japan)

1994-07-25

With regard to the GPS (global positioning system) which uses the satellites launched and administered by the U.S.A. and has been utilized worldwide for ships, automobiles and geodetic surveys in recent years, Ministry of Transport started investigation and research on the application of its position measuring system from FY 1989. In this fiscal year, a study on position measuring methods and selection of the position measuring system to be developed were made, in FY 1991, the real-time functioning and track display were developed, in FY 1992, the initialization aboard the ship, the measure to prevent cycle slip, and the radio data communication technology were developed, and in FY 1993, a long term demonstration experiment presuming its practical use was conducted attaining the expected purpose. In this article, the developed real-time kinematic position measuring system is introduced. Regarding the position measuring methods by the GPS, there are the one point position measuring method and the relative position measuring method. Regarding this newly developed position measuring device, its application to work ships and structures can be considered in various ways. 4 figs.

A Geometry-Based Cycle Slip Detection and Repair Method with Time-Differenced Carrier Phase (TDCP for a Single Frequency Global Position System (GPS + BeiDou Navigation Satellite System (BDS Receiver

Directory of Open Access Journals (Sweden)

Chuang Qian

2016-12-01

Full Text Available As the field of high-precision applications based on carriers continues to expand, the development of low-cost, small, modular receivers and their application in diverse scenarios and situations with complex data quality has increased the requirements of carrier-phase data preprocessing. A new geometry-based cycle slip detection and repair method based on Global Position System (GPS + BeiDou Navigation Satellite System (BDS is proposed. The method uses a Time-differenced Carrier Phase (TDCP model, which eliminates the Inner-System Bias (ISB between GPS and BDS, and it is conducive to the effective combination of GPS and BDS. It avoids the interference of the noise of the pseudo-range with cycle slip detection, while the cycle slips are preserved as integers. This method does not limit the receiver frequency number, and it is applicable to single-frequency data. The process is divided into two steps to detect and repair cycle slip. The first step is cycle slip detection, using the Improved Local Analysis Method (ILAM to find satellites that have cycle slips; The second step is to repair the cycle slips, including estimating the float solution of changes in ambiguities at the satellites that have cycle slips with the least squares method and the integer solution of the cycle slips by rounding. In the process of rounding, in addition to the success probability, a decimal test is carried out to validate the result. Finally, experiments with filed test data are carried out to prove the effectiveness of this method. The results show that the detectable cycle slips number with GPS + BDS is much greater than that with GPS. The method can also detect the non-integer outliers while fixing the cycle slip. The maximum decimal bias in repair is less than that with GPS. It implies that this method takes full advantages of multi-system.

Determining of the phase centre of the real position of GPS receiver antenna

Directory of Open Access Journals (Sweden)

Eva Pisoňová

2007-06-01

Full Text Available By continued improvement of measurement methods producers of GPS (Global Positioning System apparatus will be maybe once upon a time effective to minimize a difference of the phase centre from the geometrical one, because it is probably impossible to make the GPS receiver antenna with zero eccentricity of the phase centre. In the last analysis, we do not prevent from a manufacturing error by any way in eliminate of the possible measurement errors.In the paper there is presented the measurement testing practice with aim of the phase centre real position determining of several in a market available GPS receivers in the paper. Investigation up to what standard the GPS receiver antenna phase centre variation achieves to float in an inaccuracy into GPS measurements. Testing was realized on the temporary testing baseline closely village Badín at Banská Bystrica in the Central Slovak Region. GPS receivers Locus Survey System (Ashtech, ProMark2 (Ashtech were tested.

Standardization of GPS data processing

International Nuclear Information System (INIS)

Park, Pil Ho

2001-06-01

A nationwide GPS network has been constructed with about 60 permanent GPS stations after late 1990s in Korea. For using the GPS in variety of application area like crustal deformation, positioning, or monitoring upper atmosphere, it is necessary to have ability to process the data precisely. Now Korea Astronomy Observatory has the precise GPS data processing technique in Korea because it is difficult to understand characteristics of the parameters we want to estimate, resolve the integer ambiguity, and analyze many errors. There are three reliable GPS data processing software in the world ; Bernese(University of Berne), GIPSY-OASIS(JPL), GAMIT(MIT). These software allow us to achieve millimeter accuracy in the horizontal position and about 1 cm accuracy vertically even for regional networks with a diameter of several thousand kilometers. But we established the standard of GPS data processing using Bernese as main tool and GIPSY O ASIS as side

Combining GPS measurements and IRI model predictions

International Nuclear Information System (INIS)

Hernandez-Pajares, M.; Juan, J.M.; Sanz, J.; Bilitza, D.

2002-01-01

The free electrons distributed in the ionosphere (between one hundred and thousands of km in height) produce a frequency-dependent effect on Global Positioning System (GPS) signals: a delay in the pseudo-orange and an advance in the carrier phase. These effects are proportional to the columnar electron density between the satellite and receiver, i.e. the integrated electron density along the ray path. Global ionospheric TEC (total electron content) maps can be obtained with GPS data from a network of ground IGS (international GPS service) reference stations with an accuracy of few TEC units. The comparison with the TOPEX TEC, mainly measured over the oceans far from the IGS stations, shows a mean bias and standard deviation of about 2 and 5 TECUs respectively. The discrepancies between the STEC predictions and the observed values show an RMS typically below 5 TECUs (which also includes the alignment code noise). he existence of a growing database 2-hourly global TEC maps and with resolution of 5x2.5 degrees in longitude and latitude can be used to improve the IRI prediction capability of the TEC. When the IRI predictions and the GPS estimations are compared for a three month period around the Solar Maximum, they are in good agreement for middle latitudes. An over-determination of IRI TEC has been found at the extreme latitudes, the IRI predictions being, typically two times higher than the GPS estimations. Finally, local fits of the IRI model can be done by tuning the SSN from STEC GPS observations

Progress in SLR-GPS co-location at San Juan (Argentina) station

Science.gov (United States)

Luis, Hernan; Rojas, Alvis; Adarvez, Sonia; Quinteros, Johana; Cobos, Pablo; Aracena, Andrés; Pacheco, Ana M.; Podestá, Ricardo; Actis, Eloy V.; Li, Jinzeng; Yin, Zhiqiang; Wang, Rui; Huang, Dongping; Márquez, Raúl

2012-08-01

From February, 2006, performing a Cooperation Agreement with National Astronomical Observatories of China (NAOC) of the Chinese Academy of Sciences (CAS), Observatorio Astronómico Félix Aguilar (OAFA) of Universidad Nacional de San Juan (UNSJ) is operating a SLR System (ILRS 7406 Station). From the beginning of 2012 a GPS Aztech - Micro Z CGRS is operative at the same place, which made the SLR - GPS co - location possible. The prior objective is to reach co - location between both techniques, so the Station became of 1st order in ITRF net. For that we study and adopt an appropriate strategy to select and place Survey Control Points that ensures higher precision in determination of 3D vectors between the selected reference point s. Afterwards we perform translocation tasks of receptor and antenna checking that the GPS verifies builder standards. Then we design and compensate survey control network, by means of software of our own draught. We expect to obtain definitive local ties with precision better than 3 mm, as suggested by IERS for co - located stations. There are very few stations with co - located spatial techniques in the Southern Hemisphere, so it is of great importance to have one in Argentina for improve our participation in IERS on the new realizations of ITRF from now on.

An Advanced Data Warehouse for Integrating Large Sets of GPS Data

DEFF Research Database (Denmark)

Andersen, Ove; Krogh, Benjamin Bjerre; Thomsen, Christian

2014-01-01

GPS data recorded from driving vehicles is available from many sources and is a very good data foundation for answering traffic related queries. However, most approaches so far have not considered combining GPS data from many sources into a single data warehouse. Further, the integration of GPS...... data with fuel consumption data (from the so-called CAN bus in the vehicles) and weather data has not been done. In this paper, we propose a data warehouse design for handling GPS data, fuel consumption data, and weather data. The design is fully implemented in a running system using the Postgre...

Semantic Enrichment of GPS Trajectories

NARCIS (Netherlands)

de Graaff, V.; van Keulen, Maurice; de By, R.A.

2012-01-01

Semantic annotation of GPS trajectories helps us to recognize the interests of the creator of the GPS trajectories. Automating this trajectory annotation circumvents the requirement of additional user input. To annotate the GPS traces automatically, two types of automated input are required: 1) a

GPs' and community pharmacists' opinions on medication management at transitions of care in Ireland.

Science.gov (United States)

Redmond, Patrick; Carroll, Hailey; Grimes, Tamasine; Galvin, Rose; McDonnell, Ronan; Boland, Fiona; McDowell, Ronald; Hughes, Carmel; Fahey, Tom

2016-04-01

The aim of this study was to survey GPs and community pharmacists (CPs) in Ireland regarding current practices of medication management, specifically medication reconciliation, communication between health care providers and medication errors as patients transition in care. A national cross-sectional survey was distributed electronically to 2364 GPs, 311 GP Registrars and 2382 CPs. Multivariable associations comparing GPs to CPs were generated and content analysis of free text responses was undertaken. There was an overall response rate of 17.7% (897 respondents-554 GPs/Registrars and 343 CPs). More than 90% of GPs and CPs were positive about the effects of medication reconciliation on medication safety and adherence. Sixty per cent of GPs reported having no formal system of medication reconciliation. Communication between GPs and CPs was identified as good/very good by >90% of GPs and CPs. The majority (>80%) of both groups could clearly recall prescribing errors, following a transition of care, they had witnessed in the previous 6 months. Free text content analysis corroborated the positive relationship between GPs and CPs, a frustration with secondary care communication, with many examples given of prescribing errors. While there is enthusiasm for the benefits of medication reconciliation there are limited formal structures in primary care to support it. Challenges in relation to systems that support inter-professional communication and reduce medication errors are features of the primary/secondary care transition. There is a need for an improved medication management system. Future research should focus on the identified barriers in implementing medication reconciliation and systems that can improve it. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Development of a Real-Time GPS/Seismic Displacement Meter: Applications to Civilian Infrastructure in Orange and Western Riverside Counties, California

Science.gov (United States)

Bock, Yehuda

2005-01-01

We propose a three-year applications project that will develop an Integrated Real-Time GPS/Seismic System and deploy it in Orange and Western Riverside Counties, spanning three major strike-slip faults in southern California (San Andreas, San Jacinto, and Elsinore) and significant populations and civilian infrastructure. The system relying on existing GPS and seismic networks will collect and analyze GPS and seismic data for the purpose of estimating and disseminating real-time positions and total ground displacements (dynamic, as well as static) during all phases of the seismic cycle, from fractions of seconds to years. Besides its intrinsic scientific use as a real-time displacement meter (transducer), the GPS/Seismic System will be a powerful tool for local and state decision makers for risk mitigation, disaster management, and structural monitoring (dams, bridges, and buildings). Furthermore, the GPS/Seismic System will become an integral part of California's spatial referencing and positioning infrastructure, which is complicated by tectonic motion, seismic displacements, and land subsidence. Finally, the GPS/Seismic system will also be applicable to navigation in any environment (land, sea, or air) by combining precise real-time instantaneous GPS positioning with inertial navigation systems. This development will take place under the umbrella of the California Spatial Reference Center, in partnership with local (Counties, Riverside County Flood and Water Conservation District, Metropolitan Water District), state (Caltrans), and Federal agencies (NGS, NASA, USGS), the geophysics community (SCIGN/SCEC2), and the private sector (RBF Consulting). The project will leverage considerable funding, resources, and R&D from SCIGN, CSRC and two NSF-funded IT projects at UCSD and SDSU: RoadNet (Real-Time Observatories, Applications and Data Management Network) and the High Performance Wireless Research and Education Network (HPWREN). These two projects are funded to

GPS synchronisation of harmonic and transient measurements in offshore wind farms

DEFF Research Database (Denmark)

Kocewiak, Łukasz Hubert; Arana Aristi, Iván; Hjerrild, Jesper

2012-01-01

The GPS synchronization challenges during the development, construction and installation of a measurement system for multi-point, high-speed and long-term data logging is described in this paper. The presented measurement system was tested in a rough offshore environment at Avedøre Holme and Gunf......The GPS synchronization challenges during the development, construction and installation of a measurement system for multi-point, high-speed and long-term data logging is described in this paper. The presented measurement system was tested in a rough offshore environment at Avedøre Holme...... and Gunfleet Sands Offshore wind farms. The paper will describe the application of GPS technology in synchronised measurements carried out at Avedøre Holme and Gunfleet Sands wind farms. Different aspects of software development and hardware configuration in order to optimise measurement system reliability...

Sensing Human Activity: GPS Tracking

Science.gov (United States)

van der Spek, Stefan; van Schaick, Jeroen; de Bois, Peter; de Haan, Remco

2009-01-01

The enhancement of GPS technology enables the use of GPS devices not only as navigation and orientation tools, but also as instruments used to capture travelled routes: as sensors that measure activity on a city scale or the regional scale. TU Delft developed a process and database architecture for collecting data on pedestrian movement in three European city centres, Norwich, Rouen and Koblenz, and in another experiment for collecting activity data of 13 families in Almere (The Netherlands) for one week. The question posed in this paper is: what is the value of GPS as ‘sensor technology’ measuring activities of people? The conclusion is that GPS offers a widely useable instrument to collect invaluable spatial-temporal data on different scales and in different settings adding new layers of knowledge to urban studies, but the use of GPS-technology and deployment of GPS-devices still offers significant challenges for future research. PMID:22574061

Sensing Human Activity: GPS Tracking

Directory of Open Access Journals (Sweden)

Remco de Haan

2009-04-01

Full Text Available The enhancement of GPS technology enables the use of GPS devices not only as navigation and orientation tools, but also as instruments used to capture travelled routes: as sensors that measure activity on a city scale or the regional scale. TU Delft developed a process and database architecture for collecting data on pedestrian movement in three European city centres, Norwich, Rouen and Koblenz, and in another experiment for collecting activity data of 13 families in Almere (The Netherlands for one week. The question posed in this paper is: what is the value of GPS as ‘sensor technology’ measuring activities of people? The conclusion is that GPS offers a widely useable instrument to collect invaluable spatial-temporal data on different scales and in different settings adding new layers of knowledge to urban studies, but the use of GPS-technology and deployment of GPS-devices still offers significant challenges for future research.

GPS Satellite Simulation Facility

Data.gov (United States)

Federal Laboratory Consortium — The GPS satellite simulation facility consists of a GPS satellite simulator controlled by either a Silicon Graphics Origin 2000 or PC depending upon unit under test...

GPS-deprived localisation for underground mines

CSIR Research Space (South Africa)

Hlophe, K

2010-08-31

Full Text Available robots. Opencast mines utilise the global positioning system (GPS) to obtain location information. The unavailability of this technology in underground mining has actuated numerous researchers to investigate possible alternatives. These attempts exploit...

Measurements of ionospheric TEC in the direction of GPS satellites and comparison with three ionospheric models

Directory of Open Access Journals (Sweden)

E. Zuccheretti

1997-06-01

Full Text Available The IEN Galileo Ferraris uses GPS for time and frequency synchronization. To obtain high performance it is important to reduce the error due to the ionospheric time-delay in GPS measurements. Evaluations of TEC in the direction of GPS satellites, obtained from three different ionospheric models, have been compared with corresponding measurements by GPS signal.

Validity and reliability of GPS and LPS for measuring distances covered and sprint mechanical properties in team sports.

Science.gov (United States)

Hoppe, Matthias W; Baumgart, Christian; Polglaze, Ted; Freiwald, Jürgen

2018-01-01

This study aimed to investigate the validity and reliability of global (GPS) and local (LPS) positioning systems for measuring distances covered and sprint mechanical properties in team sports. Here, we evaluated two recently released 18 Hz GPS and 20 Hz LPS technologies together with one established 10 Hz GPS technology. Six male athletes (age: 27±2 years; VO2max: 48.8±4.7 ml/min/kg) performed outdoors on 10 trials of a team sport-specific circuit that was equipped with double-light timing gates. The circuit included various walking, jogging, and sprinting sections that were performed either in straight-lines or with changes of direction. During the circuit, athletes wore two devices of each positioning system. From the reported and filtered velocity data, the distances covered and sprint mechanical properties (i.e., the theoretical maximal horizontal velocity, force, and power output) were computed. The sprint mechanical properties were modeled via an inverse dynamic approach applied to the center of mass. The validity was determined by comparing the measured and criterion data via the typical error of estimate (TEE), whereas the reliability was examined by comparing the two devices of each technology (i.e., the between-device reliability) via the coefficient of variation (CV). Outliers due to measurement errors were statistically identified and excluded from validity and reliability analyses. The 18 Hz GPS showed better validity and reliability for determining the distances covered (TEE: 1.6-8.0%; CV: 1.1-5.1%) and sprint mechanical properties (TEE: 4.5-14.3%; CV: 3.1-7.5%) than the 10 Hz GPS (TEE: 3.0-12.9%; CV: 2.5-13.0% and TEE: 4.1-23.1%; CV: 3.3-20.0%). However, the 20 Hz LPS demonstrated superior validity and reliability overall (TEE: 1.0-6.0%; CV: 0.7-5.0% and TEE: 2.1-9.2%; CV: 1.6-7.3%). For the 10 Hz GPS, 18 Hz GPS, and 20 Hz LPS, the relative loss of data sets due to measurement errors was 10.0%, 20.0%, and 15.8%, respectively. This study shows that

Remote landslide mapping using a laser rangefinder binocular and GPS

Directory of Open Access Journals (Sweden)

M. Santangelo

2010-12-01

Full Text Available We tested a high-quality laser rangefinder binocular coupled with a GPS receiver connected to a Tablet PC running dedicated software to help recognize and map in the field recent rainfall-induced landslides. The system was tested in the period between March and April 2010, in the Monte Castello di Vibio area, Umbria, Central Italy. To test the equipment, we measured thirteen slope failures that were mapped previously during a visual reconnaissance field campaign conducted in February and March 2010. For reference, four slope failures were also mapped by walking the GPS receiver along the landslide perimeter. Comparison of the different mappings revealed that the geographical information obtained remotely for each landslide by the rangefinder binocular and GPS was comparable to the information obtained by walking the GPS around the landslide perimeter, and was superior to the information obtained through the visual reconnaissance mapping. Although our tests were not exhaustive, we maintain that the system is effective to map recent rainfall induced landslides in the field, and we foresee the possibility of using the same (or similar system to map landslides, and other geomorphological features, in other areas.

The SMS-GPS-Trip-Method

DEFF Research Database (Denmark)

Reinau, Kristian Hegner; Harder, Henrik; Weber, Michael

2015-01-01

This article presents a new method for collecting travel behavior data, based on a combination of GPS tracking and SMS technology, coined the SMS–GPS-Trip method. The state-of-the-art method for collecting data for activity based traffic models is a combination of travel diaries and GPS tracking...

Global positioning system derived performance measures are responsive indicators of physical activity, disease and the success of clinical treatments in domestic dogs.

Directory of Open Access Journals (Sweden)

Elizabeth A Bruno

Full Text Available To assess the use of Global Positioning System receiver (GPS derived performance measures for differentiating between: 1 different outdoor activities in healthy dogs; 2 healthy dogs and those with osteoarthritis; 3 osteoarthritic dogs before and after treatment with non-steroidal anti-inflammatory analgesia.Prospective study.Ten healthy dogs and seven dogs with osteoarthritis of the elbow joint (OA dogs.Healthy dogs were walked on a standard route on-lead, off-lead and subjected to playing activity (chasing a ball whilst wearing a GPS collar. Each dog was walked for five consecutive days. Dogs with OA were subjected to a single off-lead walk whilst wearing a GPS collar, and then administered oral Carprofen analgesia daily for two weeks. OA dogs were then subjected to the same walk, again wearing a GPS collar.GPS derived measures of physical performance could differentiate between on-lead activity, off-lead activity and playing activity in healthy dogs, and between healthy dogs and OA dogs. Variation in the performance measures analysed was greater between individual dogs than for individual dogs on different days. Performance measures could differentiate healthy dogs from OA dogs. OA Dogs treated with Carprofen analgesia showed improvements in their physical performance, which returned to values indistinguishable from those of healthy dogs on nearly all the measures assessed.GPS derived measures of physical performance in dogs are objective, easy to quantify, and can be used to gauge the effects of disease and success of clinical treatments. Specific stimuli can be used to modulate physical performance beyond the self-governed boundaries that dogs will naturally express when allowed to exercise freely without stimulation.

Comparação de três receptores GPS para uso em agricultura de precisão Comparison of three GPS receiver for precision agriculture uses

Directory of Open Access Journals (Sweden)

Marcelo C. C. Stabile

2006-04-01

Full Text Available Diversos equipamentos que se utilizam dos sinais transmitidos pelo Sistema de Posicionamento Global (GPS têm sido empregados na Agricultura de Precisão. Neste estudo, foi feita uma comparação de três receptores comerciais no intuito de verificar suas acurácias. As principais qualidades medidas foram a repetibilidade dos dados e a estabilidade do sistema. O estudo foi conduzido em campo aberto, na área experimental da ESALQ/USP, com três linhas paralelas de 50 m espaçadas 10 m entre si. A coleta de dados foi feita no dia 25-9-2002, totalizando seis repetições da comparação dos três sistemas. Os dados foram coletados simultaneamente, de acordo com a melhor configuração da constelação de satélites, sendo que os três sistemas apresentaram resultados distintos. O GPS "A" (oito canais, sem correção diferencial apresentou a maior variabilidade e a menor repetibilidade, com desvios de quase 10 m numa mesma linha. O sistema "B", com sinal de correção diferencial (DGPS "B", 12 canais, apresentou acurácia superior ao "A", com desvios de, no máximo, 6 m, mas com repetibilidade significativa. O GPS "C" (12 canais, com algoritmo otimizado apresentou a maior acurácia e desvio máximo de 2 m. Assim, os dois últimos sistemas são adequados para a aplicação dos conceitos da Agricultura de Precisão.Several brands of equipment have been used with global positioning systems (GPS in Precision Agriculture. The quality of these different receivers varies according to their capabilities in terms of accuracy and repeatability. In this study, three commercial systems were tested to compare their accuracies. This study focused on measuring the stability of the receiver and the repeatability of data. The study was conducted in the experimental area of ESALQ/USP. It consisted of three parallel 50-meter lines spaced 10 meters apart. Data collection was done on 9-25-2002 with a total of six replications. Data was collected simultaneously and the

Soil Moisture Retrieval Based on GPS Signal Strength Attenuation

Directory of Open Access Journals (Sweden)

Franziska Koch

2016-07-01

Full Text Available Soil moisture (SM is a highly relevant variable for agriculture, the emergence of floods and a key variable in the global energy and water cycle. In the last years, several satellite missions have been launched especially to derive large-scale products of the SM dynamics on the Earth. However, in situ validation data are often scarce. We developed a new method to retrieve SM of bare soil from measurements of low-cost GPS (Global Positioning System sensors that receive the freely available GPS L1-band signals. The experimental setup of three GPS sensors was installed at a bare soil field at the German Weather Service (DWD in Munich for almost 1.5 years. Two GPS antennas were installed within the soil column at a depth of 10 cm and one above the soil. SM was successfully retrieved based on GPS signal strength losses through the integral soil volume. The results show high agreement with measured and modelled SM validation data. Due to its non-destructive, cheap and low power setup, GPS sensor networks could also be used for potential applications in remote areas, aiming to serve as satellite validation data and to support the fields of agriculture, water supply, flood forecasting and climate change.

GPS operations at Olkiluoto in 2009

Energy Technology Data Exchange (ETDEWEB)

Kallio, U.; Nyberg, S.; Koivula, H.; Jokela, J.; Poutanen, M.; Ahola, J. (Finnish Geodetic Institute, Masala (Finland))

2010-06-15

The GPS based deformation studies have been made at the investigation areas of Posiva since 1995, when the network of ten GPS pillars was established at Olkiluoto. One pillar in the investigation area belongs to the Finnish permanent GPS network, FinnRef. 28 GPS measurement campaigns have been carried out at Olkiluoto since 1995. According to the time series of the GPS results 1/3 of the baselines at Olkiluoto have statistically significant change rates. However, the observed movements are smaller than +-0.20 mm/a. There are five pillars, which have statistically significant horizontal velocities at Olkiluoto. These local velocity components are small but taking into account the standard deviations the largest velocity components seems to be reliably determined. At Olkiluoto a baseline for electronic distance measurements (EDM) was built in 2002. The baseline has been measured using EDM instruments in connection to the GPS observations. Changes in he difference between the GPS and EDM results indicate the systematic change in GPS results. No corrections based on only one baseline were not applied to GPS vectors. The GPS network at Olkiluoto was extended in 2003. The new pillars were built close to Kuivalahti village and on a small island of Iso Pyrekari. According to the geological evidence it is expected that a fracture zone is located between the new stations, thus enabling the determination of possible deformations along the fracture zone. The new pillars have been observed since 2003 and now we have computed the first deformation analysis from the six years data. Four new permanent stations will be established in summer 2010 at Olkiluoto. We have automated the processing of the campaign data by using the Bernese processing engine (BPE) together with our own Perl scripts. The local crustal deformations have been studied in GeoSatakunta project, too. This GPS network is located in Cities of Pori and Rauma and their neighbouring municipalities. Two new pillars

GPS operations at Olkiluoto in 2009

International Nuclear Information System (INIS)

Kallio, U.; Nyberg, S.; Koivula, H.; Jokela, J.; Poutanen, M.; Ahola, J.

2010-06-01

The GPS based deformation studies have been made at the investigation areas of Posiva since 1995, when the network of ten GPS pillars was established at Olkiluoto. One pillar in the investigation area belongs to the Finnish permanent GPS network, FinnRef. 28 GPS measurement campaigns have been carried out at Olkiluoto since 1995. According to the time series of the GPS results 1/3 of the baselines at Olkiluoto have statistically significant change rates. However, the observed movements are smaller than ±0.20 mm/a. There are five pillars, which have statistically significant horizontal velocities at Olkiluoto. These local velocity components are small but taking into account the standard deviations the largest velocity components seems to be reliably determined. At Olkiluoto a baseline for electronic distance measurements (EDM) was built in 2002. The baseline has been measured using EDM instruments in connection to the GPS observations. Changes in he difference between the GPS and EDM results indicate the systematic change in GPS results. No corrections based on only one baseline were not applied to GPS vectors. The GPS network at Olkiluoto was extended in 2003. The new pillars were built close to Kuivalahti village and on a small island of Iso Pyrekari. According to the geological evidence it is expected that a fracture zone is located between the new stations, thus enabling the determination of possible deformations along the fracture zone. The new pillars have been observed since 2003 and now we have computed the first deformation analysis from the six years data. Four new permanent stations will be established in summer 2010 at Olkiluoto. We have automated the processing of the campaign data by using the Bernese processing engine (BPE) together with our own Perl scripts. The local crustal deformations have been studied in GeoSatakunta project, too. This GPS network is located in Cities of Pori and Rauma and their neighbouring municipalities. Two new pillars

GPS deformation measurements at Olkiluoto in 2013

International Nuclear Information System (INIS)

Nyberg, S.; Kallio, U.; Koivula, H.

2014-08-01

The Finnish Geodetic Institute has monitored crustal deformations since mid-1990s at Olkiluoto, Kivetty and Romuvaara. The research was focused on the Olkiluoto area in 2001, when Olkiluoto was chosen to the site for the final disposal facility of the spent nuclear fuel. The work and the results of the GPS deformation monitoring at Olkiluoto in 2013 are presented. The measurement consisted of two GPS measurement campaigns, observations at local permanent stations and control markers measurements at four stations. In spring six new stations were set up for permanent tracking. In total 12 permanent stations were operating continuously from April to the end of the year. The residual time series of the stations showed periodic trends up to 3 mm in height and 1 mm in horizontal component relative to the GPS1 station. A few stations were still measured as campaign-based and analysed baseline by baseline. The data from permanent stations (GPS1-GPS9, and GPS13) were included. The analysis of the inner network based on campaign sessions showed very small motions as in previous years: 75 % of change rates are smaller than 0.10 mm/y. Roughly one third of the change rates could be considered statistically significant at 1 % significance level. Statistically significant change rates were estimated for baselines from GPS1 and GPS5. The trends and strains differed at some baselines clearly from the earlier analysis because of different troposphere modelling. The results of the outer network showed the largest difference on the baseline GPS1-GPS11 where the trend decreased from -0.42 mm/y to -0.28 mm/y. The strain pattern of the outer network shows an eastwards motion of GPS1. The estimated strains for the baselines east of GPS1 were -0.03/-0.04 ppm/y. The control marker measurements were carried at the stations GPS1, GPS2, GPS4 and GPS6. A comparison of the results with the previous measurements showed that the distance between control markers at GPS6 continues to increase. Also

GPS deformation measurements at Olkiluoto in 2013

Energy Technology Data Exchange (ETDEWEB)

Nyberg, S.; Kallio, U.; Koivula, H. [Finnish Geodetic Institute, Masala (Finland)

2014-08-15

The Finnish Geodetic Institute has monitored crustal deformations since mid-1990s at Olkiluoto, Kivetty and Romuvaara. The research was focused on the Olkiluoto area in 2001, when Olkiluoto was chosen to the site for the final disposal facility of the spent nuclear fuel. The work and the results of the GPS deformation monitoring at Olkiluoto in 2013 are presented. The measurement consisted of two GPS measurement campaigns, observations at local permanent stations and control markers measurements at four stations. In spring six new stations were set up for permanent tracking. In total 12 permanent stations were operating continuously from April to the end of the year. The residual time series of the stations showed periodic trends up to 3 mm in height and 1 mm in horizontal component relative to the GPS1 station. A few stations were still measured as campaign-based and analysed baseline by baseline. The data from permanent stations (GPS1-GPS9, and GPS13) were included. The analysis of the inner network based on campaign sessions showed very small motions as in previous years: 75 % of change rates are smaller than 0.10 mm/y. Roughly one third of the change rates could be considered statistically significant at 1 % significance level. Statistically significant change rates were estimated for baselines from GPS1 and GPS5. The trends and strains differed at some baselines clearly from the earlier analysis because of different troposphere modelling. The results of the outer network showed the largest difference on the baseline GPS1-GPS11 where the trend decreased from -0.42 mm/y to -0.28 mm/y. The strain pattern of the outer network shows an eastwards motion of GPS1. The estimated strains for the baselines east of GPS1 were -0.03/-0.04 ppm/y. The control marker measurements were carried at the stations GPS1, GPS2, GPS4 and GPS6. A comparison of the results with the previous measurements showed that the distance between control markers at GPS6 continues to increase. Also

Ionospheric earthquake effects detection based on Total Electron Content (TEC) GPS Correlation

Science.gov (United States)

Sunardi, Bambang; Muslim, Buldan; Eka Sakya, Andi; Rohadi, Supriyanto; Sulastri; Murjaya, Jaya

2018-03-01

Advances in science and technology showed that ground-based GPS receiver was able to detect ionospheric Total Electron Content (TEC) disturbances caused by various natural phenomena such as earthquakes. One study of Tohoku (Japan) earthquake, March 11, 2011, magnitude M 9.0 showed TEC fluctuations observed from GPS observation network spread around the disaster area. This paper discussed the ionospheric earthquake effects detection using TEC GPS data. The case studies taken were Kebumen earthquake, January 25, 2014, magnitude M 6.2, Sumba earthquake, February 12, 2016, M 6.2 and Halmahera earthquake, February 17, 2016, M 6.1. TEC-GIM (Global Ionosphere Map) correlation methods for 31 days were used to monitor TEC anomaly in ionosphere. To ensure the geomagnetic disturbances due to solar activity, we also compare with Dst index in the same time window. The results showed anomalous ratio of correlation coefficient deviation to its standard deviation upon occurrences of Kebumen and Sumba earthquake, but not detected a similar anomaly for the Halmahera earthquake. It was needed a continous monitoring of TEC GPS data to detect the earthquake effects in ionosphere. This study giving hope in strengthening the earthquake effect early warning system using TEC GPS data. The method development of continuous TEC GPS observation derived from GPS observation network that already exists in Indonesia is needed to support earthquake effects early warning systems.

Multi-Flight-Phase GPS Navigation Filter Applications to Terrestrial Vehicle Navigation and Positioning

Science.gov (United States)

Park, Young W.; Montez, Moises N.

1994-01-01

A candidate onboard space navigation filter demonstrated excellent performance (less than 8 meter level RMS semi-major axis accuracy) in performing orbit determination of a low-Earth orbit Explorer satellite using single-frequency real GPS data. This performance is significantly better than predicted by other simulation studies using dual-frequency GPS data. The study results revealed the significance of two new modeling approaches evaluated in the work. One approach introduces a single-frequency ionospheric correction through pseudo-range and phase range averaging implementation. The other approach demonstrates a precise axis-dependent characterization of dynamic sample space uncertainty to compute a more accurate Kalman filter gain. Additionally, this navigation filter demonstrates a flexibility to accommodate both perturbational dynamic and observational biases required for multi-flight phase and inhomogeneous application environments. This paper reviews the potential application of these methods and the filter structure to terrestrial vehicle and positioning applications. Both the single-frequency ionospheric correction method and the axis-dependent state noise modeling approach offer valuable contributions in cost and accuracy improvements for terrestrial GPS receivers. With a modular design approach to either 'plug-in' or 'unplug' various force models, this multi-flight phase navigation filter design structure also provides a versatile GPS navigation software engine for both atmospheric and exo-atmospheric navigation or positioning use, thereby streamlining the flight phase or application-dependent software requirements. Thus, a standardized GPS navigation software engine that can reduce the development and maintenance cost of commercial GPS receivers is now possible.

Temporal and Spatial Characterization of GPS Fading From Ionospheric Irregularities Under Low latitude

Science.gov (United States)

De Paula, E. R.; Moraes, A. D. O.; Vani, B. C.; Sobral, J. H. A.; Abdu, M. A.; Galera Monico, J. F.

2017-12-01

The ionosphere over the peak of the anomaly represents a treat for navigation systems based on GNSS. Brazilian territory is mostly under this harsh layer for satellite communication in general and in particular for navigation, like GPS users, where their receivers tracking performance are damaged under scintillation conditions. Ionospheric scintillation is responsible for significant degradation in the accuracy of navigation and positioning. Phase shifts accompanied by amplitude fades significantly degrades the signal-to-noise ratio of the received signal disrupting the channel and loosing navigation performance. The stronger the scintillations are, more difficulty will be for the GNSS receiver tracking loops to recover the phase and code replicas. These phenomena under specific geophysical conditions may severely affect the system availability and positioning. In this work the temporal characteristics of amplitude scintillation will be analyzed at the three available GPS frequencies, L1, L2C and L5. Aspect like fading duration and depth will be evaluated and compared among the three available frequencies for the current solar cycle. This work will use GPS scintillation data recorded during six months of data during 2014 to 2015 at three stations under Brazilian territory located near the southern crest of the equatorial ionization anomaly. The analysis will be performed focusing on the fading profile of the three frequencies comparing how the fading of those signals behave statistically between them. Aspects like loss of lock, spatial orientation between the signal across the ionospheric irregularity will also be discussed showing how much more susceptible the new frequencies might be in comparison to the widely used and studied L1 frequency.

The impact of GPS receiver modifications and ionospheric activity on Swarm baseline determination

Science.gov (United States)

Mao, X.; Visser, P. N. A. M.; van den IJssel, J.

2018-05-01

The European Space Agency (ESA) Swarm mission is a satellite constellation launched on 22 November 2013 aiming at observing the Earth geomagnetic field and its temporal variations. The three identical satellites are equipped with high-precision dual-frequency Global Positioning System (GPS) receivers, which make the constellation an ideal test bed for baseline determination. From October 2014 to August 2016, a number of GPS receiver modifications and a new GPS Receiver Independent Exchange Format (RINEX) converter were implemented. Moreover, the on-board GPS receiver performance has been influenced by the ionospheric scintillations. The impact of these factors is assessed for baseline determination of the pendulum formation flying Swarm-A and -C satellites. In total 30 months of data - from 15 July 2014 to the end of 2016 - is analyzed. The assessment includes analysis of observation residuals, success rate of GPS carrier phase ambiguity fixing, a consistency check between the so-called kinematic and reduced-dynamic baseline solution, and validations of orbits by comparing with Satellite Laser Ranging (SLR) observations. External baseline solutions from The German Space Operations Center (GSOC) and Astronomisches Institut - Universität Bern (AIUB) are also included in the comparison. Results indicate that the GPS receiver modifications and RINEX converter changes are effective to improve the baseline determination. This research eventually shows a consistency level of 9.3/4.9/3.0 mm between kinematic and reduced-dynamic baselines in the radial/along-track/cross-track directions. On average 98.3% of the epochs have kinematic solutions. Consistency between TU Delft and external reduced-dynamic baseline solutions is at a level of 1 mm level in all directions.

Comparative Analysis of Several Real-Time Systems for Tracking People and/or Moving Objects using GPS

OpenAIRE

Radinski, Gligorcho; Mileva, Aleksandra

2015-01-01

When we talk about real-time systems for tracking people and/or moving objects using a Global Positioning System (GPS), there are several categories of such systems and the ways in which they work. Some uses additional hardware to extend the functionality of the offered opportunities, some are free, some are too complex and cost too much money. This paper aims to provide a clearer picture of several such systems and to show results from a comparative analysis of some popular systems for trac...

Integrating GPS with Dead Reckoning Sensors

DEFF Research Database (Denmark)

Cederholm, Jens Peter

2000-01-01

A vehicle positioning system comprising a GPS receiver, a digital compass, and an odometer was tested on a 2.8-km stretch in Aalborg, Denmark. The system, which merges observations from the three instruments using a Kalman filter, has an update rate of 1 Hz and is intended for use in both urban a...

Why do GPs leave direct patient care and what might help to retain them? A qualitative study of GPs in South West England.

Science.gov (United States)

Sansom, Anna; Terry, Rohini; Fletcher, Emily; Salisbury, Chris; Long, Linda; Richards, Suzanne H; Aylward, Alex; Welsman, Jo; Sims, Laura; Campbell, John L; Dean, Sarah G

2018-01-10

To identify factors influencing general practitioners' (GPs') decisions about whether or not to remain in direct patient care in general practice and what might help to retain them in that role. Qualitative, in-depth, individual interviews exploring factors related to GPs leaving, remaining in and returning to direct patient care. South West England, UK. 41 GPs: 7 retired; 8 intending to take early retirement; 11 who were on or intending to take a career break; 9 aged under 50 years who had left or were intending to leave direct patient care and 6 who were not intending to leave or to take a career break. Plus 19 stakeholders from a range of primary care-related professional organisations and roles. Reasons for leaving direct patient care were complex and based on a range of job-related and individual factors. Three key themes underpinned the interviewed GPs' thinking and rationale: issues relating to their personal and professional identity and the perceived value of general practice-based care within the healthcare system; concerns regarding fear and risk, for example, in respect of medical litigation and managing administrative challenges within the context of increasingly complex care pathways and environments; and issues around choice and volition in respect of personal social, financial, domestic and professional considerations. These themes provide increased understanding of the lived experiences of working in today's National Health Service for this group of GPs. Future policies and strategies aimed at retaining GPs in direct patient care should clarify the role and expectations of general practice and align with GPs' perception of their own roles and identity; demonstrate to GPs that they are valued and listened to in planning delivery of the UK healthcare; target GPs' concerns regarding fear and risk, seeking to reduce these to manageable levels and give GPs viable options to support them to remain in direct patient care. © Article author(s) (or their

Implementasi Sistem Pelacakan Kendaraan Bermotor Menggunakan Gps Dan Gprs Dengan Integrasi Googlemap

OpenAIRE

Yazid Dul Muchlisin; Jazi Eko Istiyanto

2011-01-01

Abstract— Vehicle tracking system using GPS and GPRS integration googlemap provide information that is maximized with the technology of GPS (Global Positioning System) receiver which can indicate the position of the vehicle with the map and the ability of the appointment of direction and position coordinates (x, y or latitude, longitude) textually and visual at any location. Vehicle tracking system is built using equipment GIS (Geographic Information System) and dedicated to smartphones which...

GPS tomography tests for DInSAR applications on Mt. Etna

Directory of Open Access Journals (Sweden)

Massimo Aranzulla

2015-07-01

Full Text Available Tropospheric artifacts of SAR images in a volcanic area like Mt. Etna cause ambiguity in the interpretation of deformations with such technique. It would be useful to measure the delay caused by tropospheric anomalies in synthetic aperture radar (SAR satellite signals (phase of the back-scattered radar wave that could be interpreted as deformation. From the delay estimated through the GPS data processing, the tropospheric tomography of electromagnetic waves refractivity, has been performed using the SIMULps12 software. The aim of this study was to perform software synthetic tests by using SIMULps12 applied to atmospheric tomography and to verify the influence of the different GPS geodetic network configurations on obtaining a reliable tomography. Three different anomalies of increasing complexity have been investigated in order to understand the representative parameters of a correct tomography, the best spatial resolution and the portions of space in which the tomography is reliable. The tests also focused on fixing/establishing the a-priori atmospheric model and the critical values of the main parameters involved in the tomographic inversion. To this end, we made a random choice of two days, necessary to define the tomographic problem. Three different network configurations with 15, 30 and 90 GPS receivers were studied. The results indicate that the well-resolved area of tomographic images increases with the number of GPS receivers not linearly, and that the actual GPS network of 42 receivers is capable of revealing/detecting the atmospheric anomalies.

Global Ionospheric Modelling using Multi-GNSS: BeiDou, Galileo, GLONASS and GPS.

Science.gov (United States)

Ren, Xiaodong; Zhang, Xiaohong; Xie, Weiliang; Zhang, Keke; Yuan, Yongqiang; Li, Xingxing

2016-09-15

The emergence of China's Beidou, Europe's Galileo and Russia's GLONASS satellites has multiplied the number of ionospheric piercing points (IPP) offered by GPS alone. This provides great opportunities for deriving precise global ionospheric maps (GIMs) with high resolution to improve positioning accuracy and ionospheric monitoring capabilities. In this paper, the GIM is developed based on multi-GNSS (GPS, GLONASS, BeiDou and Galileo) observations in the current multi-constellation condition. The performance and contribution of multi-GNSS for ionospheric modelling are carefully analysed and evaluated. Multi-GNSS observations of over 300 stations from the Multi-GNSS Experiment (MGEX) and International GNSS Service (IGS) networks for two months are processed. The results show that the multi-GNSS GIM products are better than those of GIM products based on GPS-only. Differential code biases (DCB) are by-products of the multi-GNSS ionosphere modelling, the corresponding standard deviations (STDs) are 0.06 ns, 0.10 ns, 0.18 ns and 0.15 ns for GPS, GLONASS, BeiDou and Galileo, respectively in satellite, and the STDs for the receiver are approximately 0.2~0.4 ns. The single-frequency precise point positioning (SF-PPP) results indicate that the ionospheric modelling accuracy of the proposed method based on multi-GNSS observations is better than that of the current dual-system GIM in specific areas.

System Proposal for Mass Transit Service Quality Control Based on GPS Data.

Science.gov (United States)

Padrón, Gabino; Cristóbal, Teresa; Alayón, Francisco; Quesada-Arencibia, Alexis; García, Carmelo R

2017-06-16

Quality is an essential aspect of public transport. In the case of regular public passenger transport by road, punctuality and regularity are criteria used to assess quality of service. Calculating metrics related to these criteria continuously over time and comprehensively across the entire transport network requires the handling of large amounts of data. This article describes a system for continuously and comprehensively monitoring punctuality and regularity. The system uses location data acquired continuously in the vehicles and automatically transferred for analysis. These data are processed intelligently by elements that are commonly used by transport operators: GPS-based tracking system, onboard computer and wireless networks for mobile data communications. The system was tested on a transport company, for which we measured the punctuality of one of the routes that it operates; the results are presented in this article.

Reduction Vehicle Speed Using GPS Android Smart Phone Programming

Directory of Open Access Journals (Sweden)

Sameer Sami Hassan

2017-07-01

Full Text Available Today the new generation of smart phone such as Samsung galaxy, Sony, Motorola, HTC is used to build smart applications that made the human life more comfortable and safe. The Android open source operating system with java programming language can be used to develop such applications. In this paper a new software application has been developed using Samsung, galaxy note smart phone to control the speed of vehicle using GPS and Android programming for such smart phone. By collecting the speed and location information from Global Position System (GPS receiver and using the global map application programming interface to determine the location nearby university, school and hospital in Baghdad city. The application will be check the speed of vehicle in zone of school, hospital and university using GPS information. If the speed over the limit the application produce sound alarm to reduce the speed to set up limit.

USGS earthquake hazards program (EHP) GPS use case : earthquake early warning (EEW) and shake alert

Science.gov (United States)

2017-03-30

GPS Adjacent Band Workshop VI RTCA Inc., Washington D.C., 30 March 2017. USGS GPS receiver use case - Real-Time GPS for EEW -Continued: CRITICAL EFFECT - The GNSS component of the Shake Alert system augments the inertial sensors and is especial...

Overview of GPS Adjacent Band Compatibility Assessment

Science.gov (United States)

2014-09-18

January 13, 2012 National SpaceBased Positioning, Navigation, and Timing (PNT) Executive Committee (EXCOM) cochair letter to National Telecommunications and Information Administration (NTIA) proposed to draft new Global Positioning System (GPS)...

Global Positioning System Derived Performance Measures Are Responsive Indicators of Physical Activity, Disease and the Success of Clinical Treatments in Domestic Dogs

Science.gov (United States)

Bruno, Elizabeth A.; Guthrie, James W.; Ellwood, Stephen A.; Mellanby, Richard J.; Clements, Dylan N.

2015-01-01

Objective To assess the use of Global Positioning System receiver (GPS) derived performance measures for differentiating between: 1) different outdoor activities in healthy dogs; 2) healthy dogs and those with osteoarthritis; 3) osteoarthritic dogs before and after treatment with non-steroidal anti-inflammatory analgesia. Design Prospective study. Animals Ten healthy dogs and seven dogs with osteoarthritis of the elbow joint (OA dogs). Procedure Healthy dogs were walked on a standard route on-lead, off-lead and subjected to playing activity (chasing a ball) whilst wearing a GPS collar. Each dog was walked for five consecutive days. Dogs with OA were subjected to a single off-lead walk whilst wearing a GPS collar, and then administered oral Carprofen analgesia daily for two weeks. OA dogs were then subjected to the same walk, again wearing a GPS collar. Results GPS derived measures of physical performance could differentiate between on-lead activity, off-lead activity and playing activity in healthy dogs, and between healthy dogs and OA dogs. Variation in the performance measures analysed was greater between individual dogs than for individual dogs on different days. Performance measures could differentiate healthy dogs from OA dogs. OA Dogs treated with Carprofen analgesia showed improvements in their physical performance, which returned to values indistinguishable from those of healthy dogs on nearly all the measures assessed. Conclusions and Clinical Relevance GPS derived measures of physical performance in dogs are objective, easy to quantify, and can be used to gauge the effects of disease and success of clinical treatments. Specific stimuli can be used to modulate physical performance beyond the self-governed boundaries that dogs will naturally express when allowed to exercise freely without stimulation. PMID:25692761

Seasonal and circadian biases in bird tracking with solar GPS-tags.

Directory of Open Access Journals (Sweden)

Rafa Silva

Full Text Available Global Positioning System (GPS tags are nowadays widely used in wildlife tracking. This geolocation technique can suffer from fix loss biases due to poor satellite GPS geometry, that result in tracking data gaps leading to wrong research conclusions. In addition, new solar-powered GPS tags deployed on birds can suffer from a new "battery drain bias" currently ignored in movement ecology analyses. We use a GPS tracking dataset of bearded vultures (Gypaetus barbatus, tracked for several years with solar GPS tags, to evaluate the causes and triggers of fix and data retrieval loss biases. We compare two models of solar GPS tags using different data retrieval systems (Argos vs GSM-GPRS, and programmed with different duty cycles. Neither of the models was able to accomplish the duty cycle programed initially. Fix and data retrieval loss rates were always greater than expected, and showed non-random gaps in GPS locations. Number of fixes per month of tracking was a bad criterion to identify tags with smaller biases. Fix-loss rates were four times higher due to battery drain than due to poor GPS satellite geometry. Both tag models were biased due to the uneven solar energy available for the recharge of the tag throughout the annual cycle, resulting in greater fix-loss rates in winter compared to summer. In addition, we suggest that the bias found along the diurnal cycle is linked to a complex three-factor interaction of bird flight behavior, topography and fix interval. More fixes were lost when vultures were perching compared to flying, in rugged versus flat topography. But long fix-intervals caused greater loss of fixes in dynamic (flying versus static situations (perching. To conclude, we emphasize the importance of evaluating fix-loss bias in current tracking projects, and deploying GPS tags that allow remote duty cycle updates so that the most appropriate fix and data retrieval intervals can be selected.

Development of automatic techniques for GPS data management

International Nuclear Information System (INIS)

Park, Pil Ho

2001-06-01

It is necessary for GPS center to establish automatization as effective management of GPS network including data gathering, data transformation, data backup, data sending to IGS (International GPS Service for geodynamics), and precise ephemerides gathering. The operating program of GPS center has been adopted at KCSC (Korea Cadastral Survey Corporation), NGI (National Geography Institute), MOMAF (Ministry of Maritime Affairs and Fisheries) without self-development of core technique. The automatic management of GPS network is consists of GPS data management and data processing. It is also fundamental technique, which should be accomplished by every GPS centers. Therefore, this study carried out analyzing of Japanese GPS center, which has accomplished automatization by module considering applicability for domestic GPS centers

GPS Time Synchronization in School-Network Cosmic Ray Detectors

Science.gov (United States)

Berns, H.-G.; Burnett, T. H.; Gran, R.; Wilkes, R. J.

2004-06-01

The QuarkNet DAQ card for school-network cosmic ray detectors provides a low-cost alternative to using standard particle and nuclear physics fast pulse electronics modules. The board, which can be produced at a cost of less than $500.00 (USD), produces trigger time and pulse edge time data for 2- to 4-fold coincidence levels via a universal RS232 serial port interface, usable with any PC. Individual detector stations, each consisting of four scintillation counter modules, front-end electronics, and a GPS receiver, produce a stream of data in form of ASCII text strings in identifiable set of formats for different functions. The card includes a low-cost GPS receiver module, which permits time-stamping event triggers to about 50 nanosecond accuracy in UTC between widely separated sites. The technique used for obtaining precise GPS time employs the 1PPS signal, which is not normally available to users of the commercial GPS module. We had the stock model slightly custom-modified to access this signal. The method for deriving time values was adapted from methods developed for the K2K long-baseline neutrino experiment. Performance of the low-cost GPS module used is compared to that of a more expensive unit with known quality.

GPS in Travel and Activity Surveys

DEFF Research Database (Denmark)

Nielsen, Thomas Alexander Sick; Hovgesen, Henrik Harder

2004-01-01

The use of GPS-positioning as a monitoring tool in travel and activity surveys opens up a range of possibilities. Using a personal GPS device, the locations and movements of respondents can be followed over a longer period of time. It will then be possible to analyse how the use of urban spaces...... are embedded in the wider context of activity patterns (work, school etc.). The general pattern of everyday itineraries, including route choice and time spent at different locations ?on the way? can also be analysed. If the personal GPS device is combined with an electronic questionnaire, for example...... area. The paper presents the possibilities in travel and activity surveys with GPS and electronic questionnaires. Demonstrative mapping of test data from passive GPS registration of Copenhagen respondents is presented. The different survey possibilities given a combination of GPS and PDA based...

Global Positioning System receiver evaluation results

Energy Technology Data Exchange (ETDEWEB)

Byrne, R.H.

1993-09-01

A Sandia project currently uses an outdated Magnavox 6400 Global Positioning System (GPS) receiver as the core of its navigation system. The goal of this study was to analyze the performance of the current GPS receiver compared to newer, less expensive models and to make recommendations on how to improve the performance of the overall navigation system. This paper discusses the test methodology used to experimentally analyze the performance of different GPS receivers, the test results, and recommendations on how an upgrade should proceed. Appendices contain detailed information regarding the raw data, test hardware, and test software.

How does the workload and work activities of procedural GPs compare to non-procedural GPs?

Science.gov (United States)

Russell, Deborah J; McGrail, Matthew R

2017-08-01

To investigate patterns of Australian GP procedural activity and associations with: geographical remoteness and population size hours worked in hospitals and in total; and availability for on-call DESIGN AND PARTICIPANTS: National annual panel survey (Medicine in Australia: Balancing Employment and Life) of Australian GPs, 2011-2013. Self-reported geographical work location, hours worked in different settings, and on-call availability per usual week, were analysed against GP procedural activity in anaesthetics, obstetrics, surgery or emergency medicine. Analysis of 9301 survey responses from 4638 individual GPs revealed significantly increased odds of GP procedural activity in anaesthetics, obstetrics or emergency medicine as geographical remoteness increased and community population size decreased, albeit with plateauing of the effect-size from medium-sized (population 5000-15 000) rural communities. After adjusting for confounders, procedural GPs work more hospital and more total hours each week than non-procedural GPs. In 2011 this equated to GPs practising anaesthetics, obstetrics, surgery, and emergency medicine providing 8% (95%CI 0, 16), 13% (95%CI 8, 19), 8% (95%CI 2, 15) and 18% (95%CI 13, 23) more total hours each week, respectively. The extra hours are attributable to longer hours worked in hospital settings, with no reduction in private consultation hours. Procedural GPs also carry a significantly higher burden of on-call. The longer working hours and higher on-call demands experienced by rural and remote procedural GPs demand improved solutions, such as changes to service delivery models, so that long-term procedural GP careers are increasingly attractive to current and aspiring rural GPs. © 2016 National Rural Health Alliance Inc.

75 FR 28318 - Eighty-Second Meeting: RTCA Special Committee 159: Global Positioning System (GPS)

Science.gov (United States)

2010-05-20

..., GPS/Inertial, Colson Board Room. Wednesday, June 9th All Day, Working Group 2, GPS/WAAS, Hilton-ATA...-NBAA Room & Hilton-ATA Room. Friday, June 11th Plenary Session--See Agenda Below Agenda--Plenary Session--Agenda June 11th, 2010--starting at 9 a.m. MacIntosh-NBAA & Hilton-ATA Rooms Chairman's...

Ionospheric threats to the integrity of airborne GPS users

Science.gov (United States)

Datta-Barua, Seebany

The Global Positioning System (GPS) has both revolutionized and entwined the worlds of aviation and atmospheric science. As the largest and most unpredictable source of GPS positioning error, the ionospheric layer of the atmosphere, if left unchecked, can endanger the safety, or "integrity," of the single frequency airborne user. An augmentation system is a differential-GPS-based navigation system that provides integrity through independent ionospheric monitoring by reference stations. However, the monitor stations are not in general colocated with the user's GPS receiver. The augmentation system must protect users from possible ionosphere density variations occurring between its measurements and the user's. This study analyzes observations from ionospherically active periods to identify what types of ionospheric disturbances may cause threats to user safety if left unmitigated. This work identifies when such disturbances may occur using a geomagnetic measure of activity and then considers two disturbances as case studies. The first case study indicates the need for a non-trivial threat model for the Federal Aviation Administration's Local Area Augmentation System (LAAS) that was not known prior to the work. The second case study uses ground- and space-based data to model an ionospheric disturbance of interest to the Federal Aviation Administration's Wide Area Augmentation System (WAAS). This work is a step in the justification for, and possible future refinement of, one of the WAAS integrity algorithms. For both WAAS and LAAS, integrity threats are basically caused by events that may be occurring but are unobservable. Prior to the data available in this solar cycle, events of such magnitude were not known to be possible. This work serves as evidence that the ionospheric threat models developed for WARS and LAAS are warranted and that they are sufficiently conservative to maintain user integrity even under extreme ionospheric behavior.

Flight Performance Evaluation of Three GPS Receivers for Sounding Rocket Tracking

Science.gov (United States)

Bull, Barton; Diehl, James; Montenbruck, Oliver; Markgraf, Markus; Bauer, Frank (Technical Monitor)

2002-01-01

In preparation for the European Space Agency Maxus-4 mission, a sounding rocket test flight was carried out at Esrange, near Kiruna, Sweden on February 19, 2001 to validate existing ground facilities and range safety installations. Due to the absence of a dedicated scientific payload, the flight offered the opportunity to test multiple GPS receivers and assess their performance for the tracking of sounding rockets. The receivers included an Ashtech G12 HDMA receiver, a BAE (Canadian Marconi) Allstar receiver and a Mitel Orion receiver. All of them provide C/A code tracking on the L1 frequency to determine the user position and make use of Doppler measurements to derive the instantaneous velocity. Among the receivers, the G12 has been optimized for use under highly dynamic conditions and has earlier been flown successfully on NASA sounding rockets. The Allstar is representative of common single frequency receivers for terrestrial applications and received no particular modification, except for the disabling of the common altitude and velocity constraints that would otherwise inhibit its use for space application. The Orion receiver, finally, employs the same Mitel chipset as the Allstar, but has received various firmware modifications by DLR to safeguard it against signal losses and improve its tracking performance. While the two NASA receivers were driven by a common wrap-around antenna, the DLR experiment made use of a switchable antenna system comprising a helical antenna in the tip of the rocket and two blade antennas attached to the body of the vehicle. During the boost a peak acceleration of roughly l7g's was achieved which resulted in a velocity of about 1100 m/s at the end of the burn. At apogee, the rocket reached an altitude of over 80 km. A detailed analysis of the attained flight data is given together with a evaluation of different receiver designs and antenna concepts.

Accelerometer and GPS Analysis of Trail Use and Associations With Physical Activity.

Science.gov (United States)

Tamura, Kosuke; Wilson, Jeffrey S; Puett, Robin C; Klenosky, David B; Harper, William A; Troped, Philip J

2018-03-26

Concurrent use of accelerometers and global positioning system (GPS) data can be used to quantify physical activity (PA) occurring on trails. This study examined associations of trail use with PA and sedentary behavior (SB) and quantified on trail PA using a combination of accelerometer and GPS data. Adults (N = 142) wore accelerometer and GPS units for 1-4 days. Trail use was defined as a minimum of 2 consecutive minutes occurring on a trail, based on GPS data. We examined associations between trail use and PA and SB. On trail minutes of light-intensity, moderate-intensity, and vigorous-intensity PA, and SB were quantified in 2 ways, using accelerometer counts only and with a combination of GPS speed and accelerometer data. Trail use was positively associated with total PA, moderate-intensity PA, and light-intensity PA (P GPS and accelerometer data for quantifying on trail activity may be more accurate than accelerometer data alone and is useful for classifying intensity of activities such as bicycling.

Water vapour tomography using GPS phase observations: Results from the ESCOMPTE experiment

Science.gov (United States)

Nilsson, T.; Gradinarsky, L.; Elgered, G.

2007-10-01

Global Positioning System (GPS) tomography is a technique for estimating the 3-D structure of the atmospheric water vapour using data from a dense local network of GPS receivers. Several current methods utilize estimates of slant wet delays between the GPS satellites and the receivers on the ground, which are difficult to obtain with millimetre accuracy from the GPS observations. We present results of applying a new tomographic method to GPS data from the Expériance sur site pour contraindre les modèles de pollution atmosphérique et de transport d'emissions (ESCOMPTE) experiment in southern France. This method does not rely on any slant wet delay estimates, instead it uses the GPS phase observations directly. We show that the estimated wet refractivity profiles estimated by this method is on the same accuracy level or better compared to other tomographic methods. The results are in agreement with earlier simulations, for example the profile information is limited above 4 km.

Cooperative Monocular-Based SLAM for Multi-UAV Systems in GPS-Denied Environments.

Science.gov (United States)

Trujillo, Juan-Carlos; Munguia, Rodrigo; Guerra, Edmundo; Grau, Antoni

2018-04-26

This work presents a cooperative monocular-based SLAM approach for multi-UAV systems that can operate in GPS-denied environments. The main contribution of the work is to show that, using visual information obtained from monocular cameras mounted onboard aerial vehicles flying in formation, the observability properties of the whole system are improved. This fact is especially notorious when compared with other related visual SLAM configurations. In order to improve the observability properties, some measurements of the relative distance between the UAVs are included in the system. These relative distances are also obtained from visual information. The proposed approach is theoretically validated by means of a nonlinear observability analysis. Furthermore, an extensive set of computer simulations is presented in order to validate the proposed approach. The numerical simulation results show that the proposed system is able to provide a good position and orientation estimation of the aerial vehicles flying in formation.

Looking Back and Looking Forward: Reprising the Promise and Predicting the Future of Formation Flying and Spaceborne GPS Navigation Systems

Science.gov (United States)

Bauer, Frank H.; Dennehy, Neil

2015-01-01

A retrospective consideration of two 15-year old Guidance, Navigation and Control (GN&C) technology 'vision' predictions will be the focus of this paper. A look back analysis and critique of these late 1990s technology roadmaps out-lining the future vision, for two then nascent, but rapidly emerging, GN&C technologies will be performed. Specifically, these two GN&C technologies were: 1) multi-spacecraft formation flying and 2) the spaceborne use and exploitation of global positioning system (GPS) signals to enable formation flying. This paper reprises the promise of formation flying and spaceborne GPS as depicted in the cited 1999 and 1998 papers. It will discuss what happened to cause that promise to be mostly unfulfilled and the reasons why the envisioned formation flying dream has yet to become a reality. The recent technology trends over the past few years will then be identified and a renewed government interest in spacecraft formation flying/cluster flight will be highlighted. The authors will conclude with a reality-tempered perspective, 15 years after the initial technology roadmaps were published, predicting a promising future of spacecraft formation flying technology development over the next decade.

GPS-MBA: computational analysis of MHC class II epitopes in type 1 diabetes.

Science.gov (United States)

Cai, Ruikun; Liu, Zexian; Ren, Jian; Ma, Chuang; Gao, Tianshun; Zhou, Yanhong; Yang, Qing; Xue, Yu

2012-01-01

As a severe chronic metabolic disease and autoimmune disorder, type 1 diabetes (T1D) affects millions of people world-wide. Recent advances in antigen-based immunotherapy have provided a great opportunity for further treating T1D with a high degree of selectivity. It is reported that MHC class II I-A(g7) in the non-obese diabetic (NOD) mouse and human HLA-DQ8 are strongly linked to susceptibility to T1D. Thus, the identification of new I-A(g7) and HLA-DQ8 epitopes would be of great help to further experimental and biomedical manipulation efforts. In this study, a novel GPS-MBA (MHC Binding Analyzer) software package was developed for the prediction of I-A(g7) and HLA-DQ8 epitopes. Using experimentally identified epitopes as the training data sets, a previously developed GPS (Group-based Prediction System) algorithm was adopted and improved. By extensive evaluation and comparison, the GPS-MBA performance was found to be much better than other tools of this type. With this powerful tool, we predicted a number of potentially new I-A(g7) and HLA-DQ8 epitopes. Furthermore, we designed a T1D epitope database (TEDB) for all of the experimentally identified and predicted T1D-associated epitopes. Taken together, this computational prediction result and analysis provides a starting point for further experimental considerations, and GPS-MBA is demonstrated to be a useful tool for generating starting information for experimentalists. The GPS-MBA is freely accessible for academic researchers at: http://mba.biocuckoo.org.

Design and Implementation of Browser based GPS/GPRS Vehicle Positioning and Tracking System

Directory of Open Access Journals (Sweden)

Zhang Keqiang

2015-01-01

Full Text Available This paper mainly describes a vehicle positioning and tracking system which is based on browser, GPS and GPRS. And this system takes advantage of Baidu Map as basic material to show vehicle status, which enables drivers and supervisor to monitor the vehicle’s current and past positions. The vehicle’s location data is got from satellites, and these data is sent to the central server through GPRS, the central server will store formatted data into the database after the data is parsed; Later, these data stored in the database will be used by web application and displayed on the map as markers. This paper also involves the implementation on mobile side, and this system used Baidu map JavaScript interface, Ajax, JSP and JSON to implement the vehicle positioning and tracking system.

Mesure GPS sur le circuit du LIER à Lyon

OpenAIRE

GIRARD, PL; MARAIS, J

2006-01-01

Depuis quelques années le guidage immatériel pour les autobus est à l'ordre du jour et la localisation est une des contraintes à son développement. Pour subvenir à ces besoins la solution GPS est envisagée. Cette technologie en devenir comporte énormément d'avantage notamment en terme coût et de maintenance. L'expérimentation faite à Lyon met en évidence les performances maximales pouvant être obtenu en utilisant le GPS. RAPPORT DE CONTRAT

Attitude determination for small satellites using GPS signal-to-noise ratio

Science.gov (United States)

Peters, Daniel

An embedded system for GPS-based attitude determination (AD) using signal-to-noise (SNR) measurements was developed for CubeSat applications. The design serves as an evaluation testbed for conducting ground based experiments using various computational methods and antenna types to determine the optimum AD accuracy. Raw GPS data is also stored to non-volatile memory for downloading and post analysis. Two low-power microcontrollers are used for processing and to display information on a graphic screen for real-time performance evaluations. A new parallel inter-processor communication protocol was developed that is faster and uses less power than existing standard protocols. A shorted annular patch (SAP) antenna was fabricated for the initial ground-based AD experiments with the testbed. Static AD estimations with RMS errors in the range of 2.5° to 4.8° were achieved over a range of off-zenith attitudes.

LADOTD GPS technology management plan : tech summary.

Science.gov (United States)

2012-02-01

Global Positioning System (GPS) technology has been adopted by diff erent sections within the Louisiana : Department of Transportation and Development (LADOTD) over the last decade with no uniform standards : for their use, procurement, training, and...

GPS: Shaping Student Success One Conversation at a Time

Science.gov (United States)

Star, Mikhael; Collette, Lanita

2010-01-01

Increasing instructor-student interactions and improving support personnel interventions with students positively affects their academic performance, retention, and graduation rates. This article discusses the Grade Performance Status (GPS) which is Northern Arizona University's new online, academic early alert tool for increasing instructor…

GPS IPW as a Meteorological Parameter and Climate Global Change Indicator

Science.gov (United States)

Kruczyk, M.; Liwosz, T.

2011-12-01

Paper focuses on comprehensive investigation of the GPS derived IPW (Integrated Precipitable Water, also IWV) as a geophysical tool. GPS meteorology is now widely acknowledged indirect method of atmosphere sensing. First we demonstrate GPS IPW quality. Most thorough inter-technique comparisons of directly measured IPW are attainable only for some observatories (note modest percentage of GPS stations equipped with meteorological devices). Nonetheless we have managed to compare IPW series derived from GPS tropospheric solutions (ZTD mostly from IGS and EPN solutions) and some independent techniques. IPW values from meteorological sources we used are: radiosoundings, sun photometer and input fields of numerical weather prediction model. We can treat operational NWP models as meteorological database within which we can calculate IWV for all GPS stations independently from network of direct measurements (COSMO-LM model maintained by Polish Institute of Meteorology and Water Management was tried). Sunphotometer (CIMEL-318, Central Geophysical Observatory IGF PAS, Belsk, Poland) data seems the most genuine source - so we decided for direct collocation of GPS measurements and sunphotometer placing permanent GPS receiver on the roof of Belsk Observatory. Next we analyse IPW as geophysical parameter: IPW demonstrates some physical effects evoked by station location (height and series correlation coefficient as a function of distance) and weather patterns like dominant wind directions (in case of neighbouring stations). Deficiency of surface humidity data to model IPW is presented for different climates. This inadequacy and poor humidity data representation in NWP model extremely encourages investigating information exchange potential between Numerical Model and GPS network. The second and most important aspect of this study concerns long series of IPW (daily averaged) which can serve as climatological information indicator (water vapour role in climate system is hard to