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Sample records for accurate gps time-linked

  1. Accurate Realization of GPS Vertical Global Reference Frame

    Elosegui, Pedro

    2004-01-01

    The few millimeter per year level accuracy of radial global velocity estimates with the Global Positioning System (GPS) is at least an order of magnitude poorer than the accuracy of horizontal global motions. An improvement in the accuracy of radial global velocities would have a very positive impact on a number of geophysical studies of current general interest such as global sea-level and climate change, coastal hazards, glacial isostatic adjustment, atmospheric and oceanic loading, glaciology and ice mass variability, tectonic deformation and volcanic inflation, and geoid variability. The goal of this project is to improve our current understanding of GPS error sources associated with estimates of radial velocities at global scales. GPS error sources relevant to this project can be classified in two broad categories: (1) those related to the analysis of the GPS phase observable, and (2) those related to the combination of the positions and velocities of a set of globally distributed stations as determined from the analysis of GPS data important aspect in the first category include the effect on vertical rate estimates due to standard analysis choices, such as orbit modeling, network geometry, ambiguity resolution, as well as errors in models (or simply the lack of models) for clocks, multipath, phase-center variations, atmosphere, and solid-Earth tides. The second category includes the possible methods of combining and defining terrestrial reference flames for determining vertical velocities in a global scale. The latter has been the subject of our research activities during this reporting period.

  2. Accurate Localization of Communicant Vehicles using GPS and Vision Systems

    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.

  3. Accurate localization of communicant vehicles using GPS and vision system

    CHALLITA, Georges; Mousset, Stéphane; NASHASHBI, Fawzi; Bensrhair, Abdelaziz

    2009-01-01

    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 loadi...

  4. Accurate Localization of Communicant Vehicles using GPS and Vision Systems

    CHALLITA, Georges; Mousset, Stéphane; Nashashibi, Fawzi; Bensrhair, Abdelaziz

    2009-01-01

    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 loadi...

  5. GPS

    Webb, Frank H.

    2006-01-01

    Geodetic networks support the TRF requirements of NASA ESE missions. Each of SLR, VLBI, GPS substantially and uniquely contributes to TRF determination. NASA's SLR, VLBI, and GPS groups collaborate toward wide-ranging improvements in the next 5 years. NASA leverages considerable resources through its significant activity in international services. NASA faces certain challenges in continuing and advancing these activities. The Terrestrial Reference Frame (TRF) is an accurate, stable set of positions and velocities. The TRF provides the stable coordinate system that allows us to link measurements over space and time. The geodetic networks provide data for determination of the TRF as well as direct science observations.

  6. MIDAS robust trend estimator for accurate GPS station velocities without step detection

    Blewitt, Geoffrey; Kreemer, Corné; Hammond, William C.; Gazeaux, Julien

    2016-03-01

    Automatic estimation of velocities from GPS coordinate time series is becoming required to cope with the exponentially increasing flood of available data, but problems detectable to the human eye are often overlooked. This motivates us to find an automatic and accurate estimator of trend that is resistant to common problems such as step discontinuities, outliers, seasonality, skewness, and heteroscedasticity. Developed here, Median Interannual Difference Adjusted for Skewness (MIDAS) is a variant of the Theil-Sen median trend estimator, for which the ordinary version is the median of slopes vij = (xj-xi)/(tj-ti) computed between all data pairs i > j. For normally distributed data, Theil-Sen and least squares trend estimates are statistically identical, but unlike least squares, Theil-Sen is resistant to undetected data problems. To mitigate both seasonality and step discontinuities, MIDAS selects data pairs separated by 1 year. This condition is relaxed for time series with gaps so that all data are used. Slopes from data pairs spanning a step function produce one-sided outliers that can bias the median. To reduce bias, MIDAS removes outliers and recomputes the median. MIDAS also computes a robust and realistic estimate of trend uncertainty. Statistical tests using GPS data in the rigid North American plate interior show ±0.23 mm/yr root-mean-square (RMS) accuracy in horizontal velocity. In blind tests using synthetic data, MIDAS velocities have an RMS accuracy of ±0.33 mm/yr horizontal, ±1.1 mm/yr up, with a 5th percentile range smaller than all 20 automatic estimators tested. Considering its general nature, MIDAS has the potential for broader application in the geosciences.

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

    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.

  8. An Accurate and Generic Testing Approach to Vehicle Stability Parameters Based on GPS and INS

    Zhibin Miao; Hongtian Zhang; Jinzhu Zhang

    2015-01-01

    With the development of the vehicle industry, controlling stability has become more and more important. Techniques of evaluating vehicle stability are in high demand. As a common method, usually GPS sensors and INS sensors are applied to measure vehicle stability parameters by fusing data from the two system sensors. Although prior model parameters should be recognized in a Kalman filter, it is usually used to fuse data from multi-sensors. In this paper, a robust, intelligent and precise meth...

  9. GPS satellite and receiver instrumental biases estimation using least squares method for accurate ionosphere modelling

    G Sasibhushana Rao

    2007-10-01

    The positional accuracy of the Global Positioning System (GPS)is limited due to several error sources.The major error is ionosphere.By augmenting the GPS,the Category I (CAT I)Precision Approach (PA)requirements can be achieved.The Space-Based Augmentation System (SBAS)in India is known as GPS Aided Geo Augmented Navigation (GAGAN).One of the prominent errors in GAGAN that limits the positional accuracy is instrumental biases.Calibration of these biases is particularly important in achieving the CAT I PA landings.In this paper,a new algorithm is proposed to estimate the instrumental biases by modelling the TEC using 4th order polynomial.The algorithm uses values corresponding to a single station for one month period and the results confirm the validity of the algorithm.The experimental results indicate that the estimation precision of the satellite-plus-receiver instrumental bias is of the order of ± 0.17 nsec.The observed mean bias error is of the order − 3.638 nsec and − 4.71 nsec for satellite 1 and 31 respectively.It is found that results are consistent over the period.

  10. A Robust Method of Vehicle Stability Accurate Measurement Using GPS and INS

    Miao, Zhibin; Zhang, Hongtian; Zhang, Jinzhu

    2015-12-01

    With the development of the vehicle industry, controlling stability has become more and more important. Techniques of evaluating vehicle stability are in high demand. Integration of Global Positioning System (GPS) and Inertial Navigation System (INS) is a very practical method to get high-precision measurement data. Usually, the Kalman filter is used to fuse the data from GPS and INS. In this paper, a robust method is used to measure vehicle sideslip angle and yaw rate, which are two important parameters for vehicle stability. First, a four-wheel vehicle dynamic model is introduced, based on sideslip angle and yaw rate. Second, a double level Kalman filter is established to fuse the data from Global Positioning System and Inertial Navigation System. Then, this method is simulated on a sample vehicle, using Carsim software to test the sideslip angle and yaw rate. Finally, a real experiment is made to verify the advantage of this approach. The experimental results showed the merits of this method of measurement and estimation, and the approach can meet the design requirements of the vehicle stability controller.

  11. An Accurate and Generic Testing Approach to Vehicle Stability Parameters Based on GPS and INS

    Zhibin Miao

    2015-12-01

    Full Text Available With the development of the vehicle industry, controlling stability has become more and more important. Techniques of evaluating vehicle stability are in high demand. As a common method, usually GPS sensors and INS sensors are applied to measure vehicle stability parameters by fusing data from the two system sensors. Although prior model parameters should be recognized in a Kalman filter, it is usually used to fuse data from multi-sensors. In this paper, a robust, intelligent and precise method to the measurement of vehicle stability is proposed. First, a fuzzy interpolation method is proposed, along with a four-wheel vehicle dynamic model. Second, a two-stage Kalman filter, which fuses the data from GPS and INS, is established. Next, this approach is applied to a case study vehicle to measure yaw rate and sideslip angle. The results show the advantages of the approach. Finally, a simulation and real experiment is made to verify the advantages of this approach. The experimental results showed the merits of this method for measuring vehicle stability, and the approach can meet the design requirements of a vehicle stability controller.

  12. A Robust Method of Vehicle Stability Accurate Measurement Using GPS and INS

    Miao Zhibin

    2015-12-01

    Full Text Available With the development of the vehicle industry, controlling stability has become more and more important. Techniques of evaluating vehicle stability are in high demand. Integration of Global Positioning System (GPS and Inertial Navigation System (INS is a very practical method to get high-precision measurement data. Usually, the Kalman filter is used to fuse the data from GPS and INS. In this paper, a robust method is used to measure vehicle sideslip angle and yaw rate, which are two important parameters for vehicle stability. First, a four-wheel vehicle dynamic model is introduced, based on sideslip angle and yaw rate. Second, a double level Kalman filter is established to fuse the data from Global Positioning System and Inertial Navigation System. Then, this method is simulated on a sample vehicle, using Carsim software to test the sideslip angle and yaw rate. Finally, a real experiment is made to verify the advantage of this approach. The experimental results showed the merits of this method of measurement and estimation, and the approach can meet the design requirements of the vehicle stability controller.

  13. Accurate Quantification of Grassland Cover Density in an Alpine Meadow Soil Based on Remote Sensing and GPS

    LIU Yan-Sui; HU Ye-Cui; PENG Liu-Ying

    2005-01-01

    The principles of remotely estimating grassland cover density in an alpine meadow soil from space lie in the synchronous collection of in situ samples with the satellite pass and statistically linking these cover densities to their image properties according to their geographic coordinates. The principles and procedures for quantifying grassland cover density from satellite image data were presented with an example from Qinghai Lake, China demonstrating how quantification could be made more accurate through the integrated use of remote sensing and global positioning systems (GPS). An empirical model was applied to an entire satellite image to convert pixel values into ground cover density. Satellite data based on 68 field samples was used to produce a map of ten cover densities. After calibration a strong linear regression relationship (r2 = 0.745) between pixel values on the satellite image and in situ measured grassland cover density was established with an 89% accuracy level. However, to minimize positional uncertainty of field samples, integrated use of hyperspatial satellite data and GPS could be utilized. This integration could reduce disparity in ground and space sampling intervals,and improve future quantification accuracy even more.

  14. High-Accurate Deformation Monitoring System Based on GPS and COMPASS

    Xiao, Yugang; Jiang, Weiping; Xi, Ruijie; Peng, Lifeng

    2014-05-01

    The results of deformation monitoring system can be significantly enhanced in accuracy and availability with multiple GNSS systems. Phase II of COMPASS has completed a constellation of 14 satellites, 5 GEO satellites, 5 IGSO satellites and 4 MEO satellites, before the end of 2012 and can provide navigation services in Asia-Pacific areas now. Along with the release of the Interface Control Document (ICD), there are more combinations for us to select. In this study, we have developed a new deformation monitoring system based on two GNSS systems, GPS and COMPASS, with the strategy of double-difference and a wide variety of systematic error corrections. During the process of research and development, reliable methods of data preprocessing and bias fixing were used. We took advantage of the geometry-free observables (LG), Melbourne-Wubbena observables (MW) and single-difference residuals of ionosphere-free observables (LC) to detect the cycle slips of raw data, and then solved all of these cycle slips as bias parameters in the process of Least Square Algorithm to avoid the wrong repairs. As for the bias fixing, We utilized the method of bootstrap and decision function to solve the bias parameters as an integer one by one. Several steps were adopted to ensure the result of bias fixing was correct. The solution was given by 3 components of the baselines and their variances respectively, which could be used to evaluate the quality of the data-processing. Comparisons between the new system and systems which is based on single GNSS system show that the results are improved remarkably in accuracy and availability, especially in Asia-Pacific region, where the accuracy of mm-level for short baselines can be achieved easily. Along with more satellites being launched in the future, COMPASS will make more contribution to the deformation monitoring application worldwide. In addition, the solution can be further enhanced with more and more error correction models being put into

  15. High-Frequency CTD Measurements for Accurate GPS/acoustic Sea-floor Crustal Deformation Measurement System

    Tadokoro, K.; Yasuda, K.; Taniguchi, S.; Uemura, Y.; Matsuhiro, K.

    2015-12-01

    The GPS/acoustic sea-floor crustal deformation measurement system has developed as a useful tool to observe tectonic deformation especially at subduction zones. One of the factors preventing accurate GPS/acoustic sea-floor crustal deformation measurement is horizontal heterogeneity of sound speed in the ocean. It is therefore necessary to measure the gradient directly from sound speed structure. We report results of high-frequency CTD measurements using Underway CTD (UCTD) in the Kuroshio region. We perform the UCTD measurements on May 2nd, 2015 at two stations (TCA and TOA) above the sea-floor benchmarks installed across the Nankai Trough, off the south-east of Kii Peninsula, middle Japan. The number of measurement points is six at each station along circles with a diameter of 1.8 nautical miles around the sea-floor benchmark. The stations TCA and TOA are located on the edge and the interior of the Kuroshio current, respectively, judging from difference in sea water density measured at the two stations, as well as a satellite image of sea-surface temperature distribution. We detect a sound speed gradient of high speeds in the southern part and low speeds in the northern part at the two stations. At the TCA station, the gradient is noticeable down to 300 m in depth; the maximum difference in sound speed is +/- 5 m/s. The sound speed difference is as small as +/- 1.3 m/s at depths below 300 m, which causes seafloor benchmark positioning error as large as 1 m. At the TOA station, the gradient is extremely small down to 100 m in depth. The maximum difference in sound speed is less than +/- 0.3 m/s that is negligible small for seafloor benchmark positioning error. Clear gradient of high speed is observed to the depths; the maximum difference in sound speed is +/- 0.8-0.9 m/s, causing seafloor benchmark positioning error of several tens centimeters. The UCTD measurement is effective tool to detect sound speed gradient. We establish a method for accurate sea

  16. An Accurate GPS-IMU/DR Data Fusion Method for Driverless Car Based on a Set of Predictive Models and Grid Constraints

    Shiyao Wang; Zhidong Deng; Gang Yin

    2016-01-01

    A high-performance differential global positioning system (GPS)  receiver with real time kinematics provides absolute localization for driverless cars. However, it is not only susceptible to multipath effect but also unable to effectively fulfill precise error correction in a wide range of driving areas. This paper proposes an accurate GPS–inertial measurement unit (IMU)/dead reckoning (DR) data fusion method based on a set of predictive models and occupancy grid constraints. First, we employ...

  17. An Accurate GPS-IMU/DR Data Fusion Method for Driverless Car Based on a Set of Predictive Models and Grid Constraints.

    Wang, Shiyao; Deng, Zhidong; Yin, Gang

    2016-01-01

    A high-performance differential global positioning system (GPS)  receiver with real time kinematics provides absolute localization for driverless cars. However, it is not only susceptible to multipath effect but also unable to effectively fulfill precise error correction in a wide range of driving areas. This paper proposes an accurate GPS-inertial measurement unit (IMU)/dead reckoning (DR) data fusion method based on a set of predictive models and occupancy grid constraints. First, we employ a set of autoregressive and moving average (ARMA) equations that have different structural parameters to build maximum likelihood models of raw navigation. Second, both grid constraints and spatial consensus checks on all predictive results and current measurements are required to have removal of outliers. Navigation data that satisfy stationary stochastic process are further fused to achieve accurate localization results. Third, the standard deviation of multimodal data fusion can be pre-specified by grid size. Finally, we perform a lot of field tests on a diversity of real urban scenarios. The experimental results demonstrate that the method can significantly smooth small jumps in bias and considerably reduce accumulated position errors due to DR. With low computational complexity, the position accuracy of our method surpasses existing state-of-the-arts on the same dataset and the new data fusion method is practically applied in our driverless car. PMID:26927108

  18. Adaptive Missile Guidance Using GPS

    Pallavi Sharad Rupnar; Prof. A. B. Diggikar

    2013-01-01

    The name adaptive means we can guide any missile using GPS in any critical conditions. GPS guided missiles, using the exceptional navigational and surveying abilities of GPS, after being launched, could deliver a warhead to any part of the globe via the interface of the onboard computer in the missile with the GPS satellite system.GPS allows accurate targeting of various military weapons including ICBMs, cruise missiles and precision-guided munitions. Artillery projectiles with embedded GPS r...

  19. GPS without satellites

    Verges Grau, Marc

    2010-01-01

    Nowadays, there have been great advances in the location technology. The personal positioning oers a very interesting eld of research because the user walking has an unpredictable behaviour and it is dicult to assume predened routes or to take into account other implemented location techniques for vehicles or robots. An approach for integration between inertial navigation systems (INS) and GPS is presented. GPS is a navigation aid accurate and reliable but susceptible to interf...

  20. GPS Separator

    2016-01-01

    Footage of the 70 degree ISOLDE GPS separator magnet MAG70 as well as the switchyard for the Central Mass and GLM (GPS Low Mass) and GHM (GPS High Mass) beamlines in the GPS separator zone. In the GPS20 vacuum sector equipment such as the long GPS scanner 482 / 483 unit, faraday cup FC 490, vacuum valves and wiregrid piston WG210 and WG475 and radiation monitors can also be seen. Also the RILIS laser guidance and trajectory can be seen, the GPS main beamgate switch box and the actual GLM, GHM and Central Beamline beamgates in the beamlines as well as the first electrostatic quadrupoles for the GPS lines. Close up of the GHM deflector plates motor and connections and the inspection glass at the GHM side of the switchyard.

  1. Hacking GPS

    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

  2. Adaptive Missile Guidance Using GPS

    Pallavi Sharad Rupnar

    2013-05-01

    Full Text Available The name adaptive means we can guide any missile using GPS in any critical conditions. GPS guided missiles, using the exceptional navigational and surveying abilities of GPS, after being launched, could deliver a warhead to any part of the globe via the interface of the onboard computer in the missile with the GPS satellite system.GPS allows accurate targeting of various military weapons including ICBMs, cruise missiles and precision-guided munitions. Artillery projectiles with embedded GPS receivers able to withstand accelerations of 12,000 G have been developed for use in 155mm.GPS guided weapons, with their technological advances over previous, are the superior weapon of choice in modern days

  3. An Accurate GPS-IMU/DR Data Fusion Method for Driverless Car Based on a Set of Predictive Models and Grid Constraints

    Shiyao Wang

    2016-02-01

    Full Text Available A high-performance differential global positioning system (GPS  receiver with real time kinematics provides absolute localization for driverless cars. However, it is not only susceptible to multipath effect but also unable to effectively fulfill precise error correction in a wide range of driving areas. This paper proposes an accurate GPS–inertial measurement unit (IMU/dead reckoning (DR data fusion method based on a set of predictive models and occupancy grid constraints. First, we employ a set of autoregressive and moving average (ARMA equations that have different structural parameters to build maximum likelihood models of raw navigation. Second, both grid constraints and spatial consensus checks on all predictive results and current measurements are required to have removal of outliers. Navigation data that satisfy stationary stochastic process are further fused to achieve accurate localization results. Third, the standard deviation of multimodal data fusion can be pre-specified by grid size. Finally, we perform a lot of field tests on a diversity of real urban scenarios. The experimental results demonstrate that the method can significantly smooth small jumps in bias and considerably reduce accumulated position errors due to DR. With low computational complexity, the position accuracy of our method surpasses existing state-of-the-arts on the same dataset and the new data fusion method is practically applied in our driverless car.

  4. Unsupervised action classification using space-time link analysis

    Liu, Haowei; Feris, Rogerio; Krüger, Volker;

    2010-01-01

    In this paper we address the problem of unsupervised discovery of action classes in video data. Different from all existing methods thus far proposed for this task, we present a space-time link analysis approach which matches the performance of traditional unsupervised action categorization metho...

  5. GPS & Roadpricing

    Zabic, Martina

    2005-01-01

    I denne artikel præsenteres analysemetoderne og resultaterne fra et eksamensprojekt omhandlende en analyse af GPS kvaliteten i forhold til roadpricing i København. Denne undersøgelse af GPS kvaliteten i forbindelse med roadpricing, er foretaget i tilknytning til det danske AKTA forsøg (www.......akta-kbh.dk), hvor GPS data er indsamlet for 500 biler over en 2-årig periode (2001-2003). Artiklen præsenterer således en analyse af GPS nøjagtigheden med henblik på at undersøge om kvalitet og pålidelighed er tilstrækkelig, til et GPS-baseret roadpricingssystem i København. Ved GPS-baseret roadpricing, udstyres...... med henblik på enhedsomkostningerne skulle være økonomisk realisable til brug i et så omfattende roadpricingssystem. Endvidere vanskeliggøres positionerings forholdene, idet bilen der ønskes positionsbestemt er i bevægelse. Når både satellitterne og GPS modtageren er i bevægelse, reduceres...

  6. {WiFi GPS} based Combined positioning Algorithm

    Zirari, Soumaya; Canalda, Philippe; Spies, François

    2010-01-01

    International audience If nowadays, positioning becomes more and more accurate, and covers better and better a territory (indoor and outdoor), it remains territories where traditional (and basic) positioning system (GPS, gsm or WiFi) and hybrid ones (GPS-gsm, GPS-WiFi, GPS-WiFi-gsm,...) are insufficient and requires research investment treating combined positioning. In this paper we propose a GPS-WiFi combined positioning algorithm, based on trilateration technique. Real experiments and ot...

  7. GPS for land surveyors

    Van Sickle, Jan

    2008-01-01

    The GPS SignalGlobal Positioning System (GPS) Signal StructureTwo ObservablesPseudorangingCarrier Phase RangingBiases and SolutionsThe Error BudgetDifferencingThe FrameworkTechnological ForerunnersVery Long Baseline InterferometryTransitNavstar GPSGPS Segment OrganizationGPS ConstellationThe Control SegmentReceivers and MethodsCommon Features of GPS ReceiversChoosing a GPS ReceiverSome GPS Surveying MethodsCoordinatesA Few Pertinent Ideas About Geodetic Datums for GPSState Plane CoordinatesHeightsGPS Surveying TechniquesStatic GPS SurveyingReal-Time Kinematic (RTK) and Differential GPS (DGPS)T

  8. GPS activities at SLAC

    The Alignment Engineering Group of the Stanford Linear Accelerator Center (SLAC) started to use RTK (real-time kinematic) GPS equipment in order to perform structure mapping and GIS-related tasks on the SLAC campus. In a first step a continuously observing GPS station (SLAC M40) was set up. This station serves as master control station for all differential GPS activities on site and its coordinates have been determined in the well-defined global geodetic datum ITRF2000 at a given reference epoch. Some trials have been performed to test the RTK method. The tests have proven RTK to be very fast and efficient. From the first 5 months of data, an initial estimate of the station velocity of SLAC M40 has been done giving a good indication of the true site velocity. Still, at least a complete year, preferably several years, of uninterrupted data coverage is needed for allocating an accurate and reliable velocity value to SLAC M40. A good estimate of this velocity, however, is a prerequisite for making coordinate determinations comparable over time. (author)

  9. GPS Separator HD

    2016-01-01

    Footage of the 70 degree ISOLDE GPS separator magnet MAG70 as well as the switchyard for the Central Mass and GLM (GPS Low Mass) and GHM (GPS High Mass) beamlines in the GPS separator zone. In the GPS20 vacuum sector equipment such as the long GPS scanner 482 / 483 unit, faraday cup FC 490, vacuum valves and wiregrid piston WG210 and WG475 and radiation monitors can also be seen. Also the RILIS laser guidance and trajectory can be seen, the GPS main beamgate switch box and the actual GLM, GHM and Central Beamline beamgates in the beamlines as well as the first electrostatic quadrupoles for the GPS lines. Close up of the GHM deflector plates motor and connections and the inspection glass at the GHM side of the switchyard.

  10. GPS Satellite Simulation Facility

    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...

  11. GLOBAL POSITIONING SYSTEM (GPS

    Celalettin Karaali

    1996-02-01

    Full Text Available Use of GPS is becoming more widespread on surveying engineering. Especially, preference to GPS is increased by getting accuracy of order of milimeter, making observation on every weather forecast, without requiring intervisibility between station. Besides, developing new observation techniques and technologies in GPS increased its use in deformation easurements, monitoring crustal movements, mapping precise geoid maps, detail surveying, etc.

  12. GLOBAL POSITIONING SYSTEM (GPS)

    Celalettin Karaali; Ömer Yıldırım

    1996-01-01

    Use of GPS is becoming more widespread on surveying engineering. Especially, preference to GPS is increased by getting accuracy of order of milimeter, making observation on every weather forecast, without requiring intervisibility between station. Besides, developing new observation techniques and technologies in GPS increased its use in deformation easurements, monitoring crustal movements, mapping precise geoid maps, detail surveying, etc.

  13. A GPS-Based Attitude Determination System for Small Satellites

    Gershman, Daniel; Young, Kristopher; Kelsey, Anders; Eldad, Ofer; Rostoker, Jason; Mohiuddin, Shan; Cerruti, Alessandro; Peck, Mason

    2006-01-01

    This paper presents a novel, GPS-based attitude determination system (ADS). Carrier-phase differential GPS (CDGPS) accurate to within centimeters enables magnetometer-level pointing accuracy. Employing three GPS antennas allows for the determination of three independent baseline vectors, which can be combined to yield a precise attitude solution. Both simulation data for a satellite in LEO and terrestrial field test data suggest subcentimeter level accuracy, yielding an instantaneous pointing...

  14. National 2000' GPS control network of China

    2007-01-01

    An accurately unified national GPS network with more than 2500 stations, named "National 2000' GPS Control Network", signed the epoch 2000.0, has been established by integrating the existing six nationwide GPS networks of China set up by different departments with different objectives. This paper presents the characteristics of the existing GPS networks, summarizes the strategies in the integrated adjustment of the GPS network, including functional model, stochastic model as well as the adjustment principle modification. By modifying the adjustment strategies according to the characteristics of the existing GPS networks and under the support of the IGS stations, the accuracy of the integrated national GPS network is greatly improved. The datum differences among the sub networks disappear, the systematic error influences are weakened, and the effects of the outliers on the estimated coordinates and their variances are controlled. It is shown that the average standard deviation for the horizontal component is smaller than 1.0 cm, the vertical component is smaller than 2.0 cm, and the three-dimensional (3-D) position of geocenter coordinates is smaller than 3.0 cm. The exterior checking accuracy for the 3-D position is averagely better than 1.0 cm.

  15. GPS Test Facility

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

  16. GPS-Aided Video Tracking

    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.

  17. Near Real-Time High-Rate GPS Data Analysis for Earthquake and Tsunami Early Warning

    Mendoza Malia, Leonor

    2015-01-01

    GPS has evolved lately in amazing ways: accurate surveying, financial transactions, precision agriculture and vehicle navigation, among others, are fields of study where GPS capabilities are highly involved. The use of GPS for earthquake magnitude determination and tsunami early warning has been introduced in the past years, along with an improvement in the accuracy of the solutions and an increase in processing speed. Earthquake magnitude determination is mainly achieved by using GPS as seis...

  18. The application of GPS time information in the telemetry ground station

    GPS time information is a kind of practicable information resource that can be shared all over the world. Now it is the most accurate wireless time information. The major of this paper is the application information of GPS time information in telemetry. The main point introduces how to make use of the GPS time information to produce GPS-IRIG-B time code for proving ground and how to send time information to related equipment in telemetry ground station

  19. GPS Satellites Orbits: Resonance

    Luiz Danilo Damasceno Ferreira

    2009-01-01

    Full Text Available The effects of perturbations due to resonant geopotential harmonics on the semimajor axis of GPS satellites are analyzed. For some GPS satellites, secular perturbations of about 4 m/day can be obtained by numerical integration of the Lagrange planetary equations considering in the disturbing potential the main secular resonant coefficients. Amplitudes for long-period terms due to resonant coefficients are also exhibited for some hypothetical satellites orbiting in the neighborhood of the GPS satellites orbits. The results are important to perform orbital maneuvers of GPS satellites such that they stay in their nominal orbits. Also, for the GPS satellites that are not active, the long-period effects due to the resonance must be taken into account in the surveillance of the orbital evolutions of such debris.

  20. Ionospheric modelling using GPS to calibrate the MWA. 1: Comparison of first order ionospheric effects between GPS models and MWA observations

    Arora, B S; Ord, S M; Tingay, S J; Hurley-Walker, N; Bell, M; Bernardi, G; Bhat, R; Briggs, F; Callingham, J R; Deshpande, A A; Dwarakanath, K S; Ewall-Wice, A; Feng, L; For, B -Q; Hancock, P; Hazelton, B J; Hindson, L; Jacobs, D; Johnston-Hollitt, M; Kapińska, A D; Kudryavtseva, N; Lenc, E; McKinley, B; Mitchell, D; Oberoi, D; Offringa, A R; Pindor, B; Procopio, P; Riding, J; Staveley-Smith, L; Wayth, R B; Wu, C; Zheng, Q; Bowman, J D; Cappallo, R J; Corey, B E; Emrich, D; Goeke, R; Greenhill, L J; Kaplan, D L; Kasper, J C; Kratzenberg, E; Lonsdale, C J; Lynch, M J; McWhirter, S R; Morales, M F; Morgan, E; Prabu, T; Rogers, A E E; Roshi, A; Shankar, N Udaya; Srivani, K S; Subrahmanyan, R; Waterson, M; Webster, R L; Whitney, A R; Williams, A; Williams, C L

    2015-01-01

    We compare first order (refractive) ionospheric effects seen by the Murchison Widefield Array (MWA) with the ionosphere as inferred from Global Positioning System (GPS) data. The first order ionosphere manifests itself as a bulk position shift of the observed sources across an MWA field of view. These effects can be computed from global ionosphere maps provided by GPS analysis centres, namely the Center for Orbit Determination in Europe (CODE), using data from globally distributed GPS receivers. However, for the more accurate local ionosphere estimates required for precision radio astronomy applications, data from local GPS networks needs to be incorporated into ionospheric modelling. For GPS observations, the ionospheric parameters are biased by GPS receiver instrument delays, among other effects, also known as receiver Differential Code Biases (DCBs). The receiver DCBs need to be estimated for any non-CODE GPS station used for ionosphere modelling, a requirement for establishing dense GPS networks in arbitr...

  1. Arctic tides from GPS on sea ice

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

    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. The GPS measurements are compared with the Arctic tidal model AOTIM-5, which assimilates tide-gauges and...

  2. Fundamentals of GPS Receivers A Hardware Approach

    Doberstein, Dan

    2012-01-01

    While much of the current literature on GPS receivers is aimed at those intimately familiar with their workings, this volume summarizes the basic principles using as little mathematics as possible, and details the necessary specifications and circuits for constructing a GPS receiver that is accurate to within 300 meters. Dedicated sections deal with the features of the GPS signal and its data stream, the details of the receiver (using a hybrid design as exemplar), and more advanced receivers and topics including time and frequency measurements. Later segments discuss the Zarlink GPS receiver chip set, as well as providing a thorough examination of the TurboRogue receiver, one of the most accurate yet made. Guiding the reader through the concepts and circuitry, from the antenna to the solution of user position, the book’s deployment of a hybrid receiver as a basis for discussion allows for extrapolation of the core ideas to more complex, and more accurate designs. Digital methods are used, but any analogue c...

  3. Mass balance assessment using GPS

    Hulbe, Christina L.

    1993-01-01

    Mass balance is an integral part of any comprehensive glaciological investigation. Unfortunately, it is hard to determine at remote locations where there is no fixed reference. The Global Positioning System (GPS) offers a solution. Simultaneous GPS observations at a known location and the remote field site, processed differentially, will accurately position the camp site. From there, a monument planted in the firn atop the ice can also be accurately positioned. Change in the monument's vertical position is a direct indicator of ice thickness change. Because the monument is not connected to the ice, its motion is due to both mass balance change and to the settling of firn as it densifies into ice. Observations of relative position change between the monument and anchors at various depths within the firn are used to remove the settling effect. An experiment to test this method has begun at Byrd Station on the West Antarctic Ice Sheet and the first epoch of observations was made. Analysis indicates that positioning errors will be very small. It appears likely that the largest errors involved with this technique will arise from ancillary data needed to determine firn settling.

  4. GPS Activities at SLAC

    The Alignment Engineering Group of the Stanford Linear Accelerator Center (SLAC) started to use RTK (real-time kinematic) GPS equipment in order to perform structure mapping and GIS-related tasks on the SLAC campus. In a first step a continuously observing GPS station (SLAC M40) was set up. This station serves as master control station for all differential GPS activities on site and its coordinates have been determined in the well-defined global geodetic datum ITRF2000 at a given reference epoch. Some trials have been performed to test the RTK method. The tests have proven RTK to be very fast and efficient

  5. Terrain modelling by kinematical GPS survey

    G. Nico

    2005-01-01

    Full Text Available This work presents the first results of an experiment aiming to derive a high resolution Digital Terrain Model (DTM by kinematic GPS surveying. The accuracy of the DTM depends on both the operational GPS precision and the density of GPS samples. The operational GPS precision, measured in the field, is about 10cm. A Monte Carlo analysis is performed to study the dependence of the DTM error on the sampling procedure. The outcome of this analysis is that the accuracy of the topographic reconstruction is less than 1m even in areas with a density of samples as low as one sample per 100m2, and becomes about 30cm in areas with at least one sample per 10m2. The kinematic GPS technique gives a means for a fast and accurate mapping of terrain surfaces with an extension of a few km2. Examples of application are the investigation of archaeological sites and the stability analysis of landslide prone areas.

  6. Uav Onboard GPS in Positioning Determination

    Tahar, K. N.; Kamarudin, S. S.

    2016-06-01

    The establishment of ground control points is a critical issue in mapping field, especially for large scale mapping. The fast and rapid technique for ground control point's establishment is very important for small budget projects. UAV onboard GPS has the ability to determine the point positioning. The objective of this research is to assess the accuracy of unmanned aerial vehicle onboard global positioning system in positioning determination. Therefore, this research used UAV onboard GPS as an alternative to determine the point positioning at the selected area. UAV is one of the powerful tools for data acquisition and it is used in many applications all over the world. This research concentrates on the error contributed from the UAV onboard GPS during observation. There are several points that have been used to study the pattern of positioning error. All errors were analyzed in world geodetic system 84- coordinate system, which is the basic coordinate system used by the global positioning system. Based on this research, the result of UAV onboard GPS positioning could be used in ground control point establishment with the specific error. In conclusion, accurate GCP establishment could be achieved using UAV onboard GPS by applying a specific correction based on this research.

  7. Terrestrial Reference Frame from GPS and SLR

    Weiss, Jan; Bertiger, Willy; Desai, Shailen; Haines, Bruce; Sibois, Aurore

    2015-04-01

    We present strategies for realizing the terrestrial reference frame (TRF) using tracking data from terrestrial GPS receivers alone and in tandem with the GRACE and LAGEOS satellites. We generate solutions without apriori ties to the International Terrestrial Reference Frame (ITRF). Our approach relies on processing multi-day orbit arcs to take advantage of the satellite dynamics, GPS receiver and transmitter calibrations derived from low-Earth orbiter (LEO) data, and estimation strategies tuned for realizing a stable and accurate TRF. We furthermore take advantage of the geometric diversity provided by GPS tracking from GRACE, and explore the impacts of including ground-based satellite laser range (SLR) measurements to LAGEOS-1 and -2 with local ties relating the two geodetic techniques. We process data from 2003-2014 and compute Helmert transformations relative to ITRF/IGb08. With GPS alone we achieve a 3D origin offset and rate of global solutions. Scale bias and rate are 3.1 ppb and 0.01 ppb/yr in either solution. Including SLR tracking from 11 ground stations to the LAGEOS satellites from 2012-2014 yields a reduction in scale bias of 0.5-1.0 ppb depending on the weight assigned to the SLR measurements. However, scatter is increased due to the relatively sparse SLR tracking network. We conclude with approaches for improving the TRF realized from GPS and SLR combined at the measurement level.

  8. Coal mining GPS subsidence monitoring technology and its application

    Wang Jian; Peng Xiangguo; Xu Chang hui

    2011-01-01

    We proved theoretically that geodetic height,measured with Global Positioning System (GPS),can be applied directly to monitor coal mine subsidence.Based on a Support Vector Machine (SVM) model,we built a regional geoid model with a Gaussian Radial Basis Function (RBF) and the technical scheme for GPS coal mine subsidence monitoring is presented to provide subsidence information for updating the regional Digital Elevation Model (DEM).The theory proposed was applied to monitor mining subsidence in an Inner Mongolia coal mine in China.The scheme established an accurate GPS reference network and a comprehensive leveling conjunction provided the normal height of all GPS control points.According to the case study,the SVM model to establish geoid-model is better than a polynomial fit or a Genetic Algorithm based Back Propagation (GA-BP) neural network.GPS-RTK measurements of coal mine subsidence information can be quickly acquired for updating the DEM.

  9. How and Why to do VLBI on GPS

    Dickey, John M

    2010-01-01

    In order to establish the position of the center of mass of the Earth in the International Celestial Reference Frame, observations of the Global Positioning Satellite (GPS) constellation using the IVS network are important. With a good frame-tie between the coordinates of the IVS telescopes and nearby GPS receivers, plus a common local oscillator reference signal, it should be possible to observe and record simultaneously signals from the astrometric calibration sources and the GPS satellites. The standard IVS solution would give the atmospheric delay and clock offsets to use in analysis of the GPS data. Correlation of the GPS signals would then give accurate orbital parameters of the satellites {\\bf in the ICRF reference frame}, i.e. relative to the positions of the astrometric sources. This is particularly needed to determine motion of the center of mass of the earth along the rotation axis.

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

    Jensen, Kjeld; Larsen, Morten; Simonsen, Tom;

    2012-01-01

    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...... driving in a simulated row crop field. The GPS supports raw data output as well and similar experiments were performed to evaluate the GPS when used in a RTK setup. In field tests more than 95% of the position errors were estimated to be within 2.6 m. In RTK field tests more than 95% of the position...

  11. Kartlegging av step-pool-morfologi med differensiell GPS

    Iversen, Magnus

    2013-01-01

    Selected reaches of a step-pool-river in Oppdal, Norway were surveyed using differential GPS. Step-pools is a morphology characteristic of upland rivers with high gradient and large supply of coarse sediments, where channel units are restructured by floods of high magnitude. Differential GPS produces real-time corrected, highly accurate satellite-based positioning and height measurements.The goal of the study was to measure changes in morphologic variables from the spring flood period between...

  12. Ralliauton GPS-loggeri

    Virjonen, Tuomas

    2012-01-01

    Työssä suunniteltiin ja toteutettiin GPS-sijaintitietoa tallentava laite, jonka tarkoituksena on mahdollistaa kuljetun reitin tarkasteleminen rallikilpailun jälkeen. Laite tallentaa GPS-moduulilta saadut sijaintitiedot sekä nopeuden massamuistiin, Google Earth -karttasovelluksen ymmärtämään muotoon, jolloin reitti saadaan piirrettyä suoraan sovelluksen karttapohjalle. Laitteen suunnittelussa pyrittiin ottamaan huomioon, että laitetta tullaan käyttämään kilpa-ajoneuvossa kilpailun aikana, j...

  13. GPS satellite surveying

    Leick, Alfred; Tatarnikov, Dmitry

    2015-01-01

    THE MOST COMPREHENSIVE, UP-TO-DATE GUIDE ON GPS TECHNOLOGY FOR SURVEYING Three previous editions have established GPS Satellite Surveying as the definitive industry reference. Now fully updated and expanded to reflect the newest developments in the field, this Fourth Edition features cutting-edge information on GNSS antennas, precise point positioning, real-time relative positioning, lattice reduction, and much more. Expert authors examine additional tools and applications, offering complete coverage of geodetic surveying using satellite technologies. The past decade has seen a major evolut

  14. GPS, su datum vertical.

    Esteban Dörries

    2016-03-01

    Full Text Available La introducción de la metodología GPS en aplicaciones topográficas y geodésicas pone en notoria evidencia la clásica separación de sistemas de referencia en horizontal y vertical. Con GPS el posicionamiento es tridimensional, pero el concepto de altura difiere del clásico. Si se desea utilizar la información altimétrica debe contemplarse la ondulación del geoide.

  15. SPREE: Spoofing Resistant GPS Receiver

    Ranganathan, Aanjhan; Ólafsdóttir, Hildur; Capkun, Srdjan

    2016-01-01

    Global Positioning System (GPS) is used ubiquitously in a wide variety of applications ranging from navigation and tracking to modern smart grids and communication networks. However, it has been demonstrated that modern GPS receivers are vulnerable to signal spoofing attacks. For example, today it is possible to change the course of a ship or force a drone to land in an hostile area by simply spoofing GPS signals. Several countermeasures have been proposed in the past to detect GPS spoofing a...

  16. GPS pseudolites: Theory, design, and applications

    Cobb, H. Stewart

    Pseudolites (ground-based pseudo-satellite transmitters) can initialize carrier-phase differential GPS (CDGPS) navigation systems in seconds to perform real-time dynamic positioning with one-sigma errors as low as 1 cm. Previous CDGPS systems were rarely used due to cumbersome initialization procedures requiring up to 30 minutes; initialization of the carrier-phase integer ambiguities via pseudolite removes these constraints. This work describes pseudolites optimized for this application which cost two orders of magnitude less than previous pseudolites. Synchrolites (synchronized pseudolites) which derive their timing from individual Global Positioning System (GPS) satellites are also described. Synchrolites can replace the CDGPS reference station and datalink, while simultaneously serving to initialize CDGPS navigation. A cluster of well-placed synchrolites could enable CDGPS navigation even if only one GPS satellite signal is available. A prototype CDGPS system initialized by pseudolites and synchrolites was designed and tested. The goal of this system, known as the Integrity Beacon Landing System (IBLS), was to provide navigation accurate and reliable enough to land aircraft in bad weather. Flight test results for prototype pseudolite and synchrolite systems, including results from 110 fully automatic landings of a Boeing 737 airliner controlled by IBLS, are presented. Existing pseudolite applications are described, including simulation of the GPS constellation for indoor navigation experiments. Synchrolite navigation algorithms are developed and analyzed. New applications for pseudolites and synchrolites are proposed. Theoretical and practical work on the near/far problem is presented.

  17. GPS Applications in Construction

    Stranger, J. W.

    2012-01-01

    This session will explore the use of GPS technology in the construction engineering aspects of highway projects. Discussion will include control of line and grade for construction equipment and how the state inspector can verify the construction is according to plans without physical surveying stakes.

  18. The Performance Analysis of a Real-Time Integrated INS/GPS Vehicle Navigation System with Abnormal GPS Measurement Elimination

    Jhen-Kai Liao

    2013-08-01

    Full Text Available The integration of an Inertial Navigation System (INS and the Global Positioning System (GPS is common in mobile mapping and navigation applications to seamlessly determine the position, velocity, and orientation of the mobile platform. In most INS/GPS integrated architectures, the GPS is considered to be an accurate reference with which to correct for the systematic errors of the inertial sensors, which are composed of biases, scale factors and drift. However, the GPS receiver may produce abnormal pseudo-range errors mainly caused by ionospheric delay, tropospheric delay and the multipath effect. These errors degrade the overall position accuracy of an integrated system that uses conventional INS/GPS integration strategies such as loosely coupled (LC and tightly coupled (TC schemes. Conventional tightly coupled INS/GPS integration schemes apply the Klobuchar model and the Hopfield model to reduce pseudo-range delays caused by ionospheric delay and tropospheric delay, respectively, but do not address the multipath problem. However, the multipath effect (from reflected GPS signals affects the position error far more significantly in a consumer-grade GPS receiver than in an expensive, geodetic-grade GPS receiver. To avoid this problem, a new integrated INS/GPS architecture is proposed. The proposed method is described and applied in a real-time integrated system with two integration strategies, namely, loosely coupled and tightly coupled schemes, respectively. To verify the effectiveness of the proposed method, field tests with various scenarios are conducted and the results are compared with a reliable reference system.

  19. Thermal structure of intense convective clouds derived from GPS radio occultations

    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...

  20. Thermal structure of intense convective clouds derived from GPS radio occultations

    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...

  1. HEIGHT ACCURACY BASED ON DIFFERENT RTK GPS METHOD FOR ULTRALIGHT AIRCRAFT IMAGES

    K. N. Tahar

    2015-01-01

    Height accuracy is one of the important elements in surveying work especially for control point’s establishment which requires an accurate measurement. There are many methods can be used to acquire height value such as tacheometry, leveling and Global Positioning System (GPS). This study has investigated the effect on height accuracy based on different observations which are single based and network based GPS methods. The GPS network is acquired from the local network namely Iskandar...

  2. MONITORING THE DYNAMIC CHARACTERISTICS OF TALL BUILDINGS BY GPS TECHNIQUE

    2000-01-01

    Dynamic characteristics of large structures,such as tall buildings,long-span suspension,cable-stayed bridges and tall chimneys,are key to assess their drift and stress conditions.The dynamic characteristics of large structures are difficult to measure directly under the condition of earthquakes or strong winds using traditional techniques such as laser collimator,total station and accelerometers.Therefore there is a great need for developing new method or technique for this purpose.Recent advances in Global Positioning System (GPS) technology provide a great opportunity to monitor long-period changes of structures reliably.GPS receivers capable to gauge the motion at the centimeter or sub-centimeter level with sampling frequency 10Hz or even 20 Hz are now available from several manufacturers.To the authors' knowledge,the capability of identifying dynamic characteristics from GPS observations has not been widely verified.For the feasibility study on using kinematic GPS technology to identify the dynamic characteristics of tall buildings,some experiments were conducted in a simulative environment.This paper discusses in detail the experiment device,and the ways through them GPS data are recorded,processed and analyzed.With post-processing version of NovAtel's Softsurv software and auto-regressive (AR) spectral analysis method,relative displacements and corresponding vibrating frequencies have been derived from GPS observations.The results indicate that the dynamic characteristics can be identified accurately by kinematic GPS technology.

  3. Design and application of single-antenna GPS/accelerometers attitude determination system

    He Jie; Huang Xianlin; Wang Guofeng

    2008-01-01

    In view of the problem that the current single-antenna GPS attitude determination system can only determine the body attitude when the sideslip angle is zero and the multiantenna GPS/SINS integrated navigation system is of large volume, high cost, and complex structure, this approach is presented to determine the attitude based on vector space with single-antenna GPS and accelerometers in the micro inertial measurement unit (MIMU).It can provide real-time and accurate attitude information. Subsequently, the single-antenna GPS/SINS integrated navigation system is designed based on the combination of position, velocity, and attitude. Finally the semi-physical simulations of single-antenna GPS attitude determination system and single-antenna GPS/SINS integrated navigation system are carried out. The simulation results, based on measured data, show that the single-antenna GPS/SINS system can provide more accurate navigation information compared to the GPS/SINS system, based on the combination of position and velocity. Furthermore, the single-antenna GPS/SINS system is characteristic of lower cost and simpler structure. It provides the basis for the application of a single-antenna GPS/SINS integrated navigation system in a micro aerial vehicle (MAV).

  4. Arctic Tides from GPS on sea-ice

    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......) placed on sea-ice, at six different sites north of Greenland for the preliminary study of sea surface height (SSH), and tidal analysis to improve tide models in the Central Arctic. The GPS measurements are compared with the Arctic tide model AOTIM-5, which assimilates tide-gauges and altimetry data. 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....

  5. Driving without a GPS

    Lauridsen, Karen M.

    the best way possible; and that the differences in their knowledge systems is acknowledged and used as an asset in these international programmes. With these factors in place, on the other hand, programmes with international faculty and diverse student audiences in which this diversity is exploited in...... an appropriate way, may have a considerable added value that positively impacts on the knowledge, skills and competences developed by their graduates. However, lecturers often feel at a loss because they are not sure how to do this and teaching becomes like driving in unknown territory without a GPS......, thereby contributing to a possible typology of challenges and solutions in international programmes from which all attendees may benefit. They will then not have to drive without a GPS, but will have a better background for navigating the international university. Singh, P. and C. Doherty (2004) “Global...

  6. GPS and property surveying

    Drummond, J

    2015-01-01

    In 2010 the Global Positioning System (GPS) developed by the United States military was the best known Global Navigation Satellite System (GNSS). Others included Russia’s GLONASS, China’s COMPASS and Europe’s GALILEO systems. Although military satellite navigation systems can be traced back to the 1960s, their civilian uses emerged in the 1980s, initially limited to navigation positioning, not property surveying. Property surveying methods have varied both between and within nations. However,...

  7. Permanent monitoring of alpine slope instabilities with L1-GPS

    Limpach, Philippe; Geiger, Alain; Su, Zhenzhong; Beutel, Jan; Gruber, Stephan

    2013-04-01

    Since winter 2010/2011, a network of permanent GPS stations is being set up in the Matter Valley (Swiss Alps). The aim is to monitor the time variable movement of potentially instable rock glaciers. The network has been established in the framework of the X-Sense project, currently totaling more than 20 stations. X-Sense is an interdisciplinary project for monitoring alpine mass movements at multiple scales, funded by the Swiss federal program Nano-Tera within the Swiss Science Foundation. The X-Sense stations consist of low-cost L1 GPS receivers coupled with inclinometers. A part of the stations allow for on-line data transmission. The data of the X-Sense L1 GPS network is operationally processed on a daily basis with Bernese GPS software, in a fully automated processing chain. In addition, real-time solutions are computed for the on-line stations. The geodetic potential of low-cost GPS receivers for the precise monitoring of slope instabilities in mountain areas was previously investigated in a feasibility study. It is shown that low-cost GPS units are able to provide reliable and continuous time series of surface displacements at cm-level accuracy in harsh environment, using adequate differential processing techniques. Enhanced algorithms were developed to derive accurate time series of surface velocities based on the GPS displacements. It was shown that the low-cost GPS receivers allow to reliably observe surface velocities even below 1 cm/day, as well as to detect small and short-term velocity changes. In addition, the time series of more than 2 years obtained reveal the capability to detect seasonal velocity variations, as well as inter-annual variations of the velocity pattern. By providing continuous observations of surface motion, the GPS-based permanent monitoring contributes to the understanding of processes linked to permafrost-related slope instabilities.

  8. Sensing Human Activity: GPS Tracking

    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.

  9. GPS kinematics measurements accuracy testing

    Miroslav Šimčák; Vladimír Sedlák; Gabriela Nemcová

    2007-01-01

    In the paper accuracy of GPS kinematics measurements is analyzed. GPS (Global Positioning System) apparatus Stratus (Sokkia) and Pro Mark2 (Aschtech) were tested. Testing was realized on the points of the geodetic network – the testing station Badín stabilized in the Central Slovak Region nearby Banská Bystrica. The semikinematics method STOP and GO was realized from the kinematics GPS methods. The terrestrial geodetic measurements by means of using the total station Nicon 352 were also reali...

  10. Honey Bee Location- and Time-Linked Memory Use in Novel Foraging Situations: Floral Color Dependency

    Marisol Amaya-Márquez

    2014-02-01

    Full Text Available Learning facilitates behavioral plasticity, leading to higher success rates when foraging. However, memory is of decreasing value with changes brought about by moving to novel resource locations or activity at different times of the day. These premises suggest a foraging model with location- and time-linked memory. Thus, each problem is novel, and selection should favor a maximum likelihood approach to achieve energy maximization results. Alternatively, information is potentially always applicable. This premise suggests a different foraging model, one where initial decisions should be based on previous learning regardless of the foraging site or time. Under this second model, no problem is considered novel, and selection should favor a Bayesian or pseudo-Bayesian approach to achieve energy maximization results. We tested these two models by offering honey bees a learning situation at one location in the morning, where nectar rewards differed between flower colors, and examined their behavior at a second location in the afternoon where rewards did not differ between flower colors. Both blue-yellow and blue-white dimorphic flower patches were used. Information learned in the morning was clearly used in the afternoon at a new foraging site. Memory was not location-time restricted in terms of use when visiting either flower color dimorphism.

  11. GPS Estimates of Integrated Precipitable Water Aid Weather Forecasters

    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.

  12. Relativity of GPS measurement

    The relativity of Global Positioning System (GPS) pseudorange measurements is explored within the geometrical optics approximation in the curved space-time near Earth. A space-time grid for navigation is created by the discontinuities introduced in the electromagnetic field amplitude by the P-code broadcast by the GPS satellites. We compute the world function of space-time near Earth, and we use it to define a scalar phase function that describes the space-time grid. We use this scalar phase function to define the measured pseudorange, which turns out to be a two-point space-time scalar under generalized coordinate transformations. Though the measured pseudorange is an invariant, it depends on the world lines of the receiver and satellite. While two colocated receivers measure two different pseudoranges to the same satellite, they obtain the correct position and time, independent of their velocity. We relate the measured pseudorange to the geometry of space-time and find corrections to the conventional model of the pseudorange that are on the order of the gravitational radius of the Earth

  13. A software defined GPS signal simulator design

    Pan, Zhenhe

    2014-01-01

    The Global Positioning System (GPS) signal simulator plays a critical role in developing and testing GPS receivers. Unfortunately, very few commercial GPS signal simulators are user-friendly for security researchers because they fail to generate abnormal GPS signals, which are fundamentally important. In this thesis, we develop a cost efficient software defined GPS signal simulator. To reduce the design complexity, we make some reasonable assumptions about the GPS system. This simulator ...

  14. Evidential recovery from GPS devices

    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.

  15. GPS Position Time Series @ JPL

    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

  16. De GPS al mapa

    Esteban Dörries

    2016-03-01

    Full Text Available Las coordenadas Lambert obtenidas a partir de mediciones con equipos GPS de mano, llamados a veces navegadores, en ciertos casos confunden al usuario, por diferir claramente de su posición real al ser graficadas en un mapa del Instituto Geográfico Nacional (IGN: Esto puede resolverse con suficiente exactitud mediante una transformación de Molodensky, seguida de la correspondiente proyección cartográfica. Sin embargo, los tres parámetros necesarios para la transformación, supuestamente válidos para Costa Rica, se encuentran en muchas variantes y producen obviamente resultados diferentes. En este trabajo se analizan los fundamentos del problema y sus posibles soluciones, culminando con un estudio comparativo de ocho casos, que permite seleccionar los valores más adecuados para los parámetros.

  17. Precise GPS orbits for geodesy

    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.

  18. Hastighedskort for Danmark vha. GPS

    Andersen, Ove; Lahrmann, Harry; Torp, Kristian

    2011-01-01

    Hastighed på vejnettet er en central metrik indenfor trafikplanlægning og trafikoptimering. I denne artikel beskrives, hvorledes et hastighedskort for hele Danmark er skabt udelukkende vha. GPS data. To tilgangsvinkler til at beregne hastigheder vha. GPS data er præsenteret. Dette er hhv. en....... Opsummeret anses den turbaseret for at beregne det mest akkurate estimat, men metoden er meget datakrævende. Det er derfor nødvendigt at have den punktbaserede at falde tilbage på. Generelt mangler metoder til beregning af hastigheder vha. GPS data at blive valideret. Hvordan en sådan validering kan...

  19. Indoor Positioning Using GPS Revisited

    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...... availability is good in many buildings with standard material walls and roofs. The measured root mean squared 2D positioning error was below five meters in wooden buildings and below ten meters in most of the investigated brick and concrete buildings. Lower accuracies, where observed, can be linked to either...

  20. Using GPS to Detect Imminent Tsunamis

    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

  1. Improving GPS/INS Integration through Neural Networks

    Nguyen-H, M

    2010-01-01

    The Global Positioning Systems (GPS) and Inertial Navigation System (INS) technology have attracted a considerable importance recently because of its large number of solutions serving both military as well as civilian applications. This paper aims to develop a more efficient and especially a faster method for processing the GPS signal in case of INS signal loss without losing the accuracy of the data. The conventional or usual method consists of processing data through a neural network and obtaining accurate positioning output data. The new or improved method adds selective filtering at the low-band frequency, the mid-band frequency and the high band frquency, before processing the GPS data through the neural network, so that the processing time is decreased significantly while the accuracy remains the same.

  2. Next Generation GPS Ground Control Segment (OCX) Navigation Design

    Bertiger, Willy; Bar-Sever, Yoaz; Harvey, Nate; Miller, Kevin; Romans, Larry; Weiss, Jan; Doyle, Larry; Solorzano, Tara; Petzinger, John; Stell, Al

    2010-01-01

    In February 2010, a Raytheon-led team was selected by The Air Force to develop, implement, and operate the next generation GPS ground control segment (OCX). To meet and exceed the demanding OCX navigation performance requirements, the Raytheon team partnered with ITT (Navigation lead) and JPL to adapt major elements of JPL's navigation technology, proven in the operations of the Global Differential GPS (GDGPS) System. Key design goals for the navigation subsystem include accurate ephemeris and clock accuracy (user range error), ease of model upgrades, and a smooth and safe transition from the legacy system to OCX.We will describe key elements of the innovative architecture of the OCX navigation subsystem,and demonstrate the anticipated performance of the system through high fidelity simulations withactual GPS measurements.

  3. Automatic Road Centerline Extraction from Imagery Using Road GPS Data

    Chuqing Cao

    2014-09-01

    Full Text Available Road centerline extraction from imagery constitutes a key element in numerous geospatial applications, which has been addressed through a variety of approaches. However, most of the existing methods are not capable of dealing with challenges such as different road shapes, complex scenes, and variable resolutions. This paper presents a novel method for road centerline extraction from imagery in a fully automatic approach that addresses the aforementioned challenges by exploiting road GPS data. The proposed method combines road color feature with road GPS data to detect road centerline seed points. After global alignment of road GPS data, a novel road centerline extraction algorithm is developed to extract each individual road centerline in local regions. Through road connection, road centerline network is generated as the final output. Extensive experiments demonstrate that our proposed method can rapidly and accurately extract road centerline from remotely sensed imagery.

  4. Integrating GIS and GPS in environmental remediation oversight

    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

  5. Real-time estimation of ionospheric delay using GPS measurements

    Lin, Lao-Sheng

    1997-12-01

    When radio waves such as the GPS signals propagate through the ionosphere, they experience an extra time delay. The ionospheric delay can be eliminated (to the first order) through a linear combination of L1 and L2 observations from dual-frequency GPS receivers. Taking advantage of this dispersive principle, one or more dual- frequency GPS receivers can be used to determine a model of the ionospheric delay across a region of interest and, if implemented in real-time, can support single-frequency GPS positioning and navigation applications. The research objectives of this thesis were: (1) to develop algorithms to obtain accurate absolute Total Electron Content (TEC) estimates from dual-frequency GPS observables, and (2) to develop an algorithm to improve the accuracy of real-time ionosphere modelling. In order to fulfil these objectives, four algorithms have been proposed in this thesis. A 'multi-day multipath template technique' is proposed to mitigate the pseudo-range multipath effects at static GPS reference stations. This technique is based on the assumption that the multipath disturbance at a static station will be constant if the physical environment remains unchanged from day to day. The multipath template, either single-day or multi-day, can be generated from the previous days' GPS data. A 'real-time failure detection and repair algorithm' is proposed to detect and repair the GPS carrier phase 'failures', such as the occurrence of cycle slips. The proposed algorithm uses two procedures: (1) application of a statistical test on the state difference estimated from robust and conventional Kalman filters in order to detect and identify the carrier phase failure, and (2) application of a Kalman filter algorithm to repair the 'identified carrier phase failure'. A 'L1/L2 differential delay estimation algorithm' is proposed to estimate GPS satellite transmitter and receiver L1/L2 differential delays. This algorithm, based on the single-site modelling technique, is

  6. GPS Navigation and Tracking Device

    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.

  7. Scintillation-Hardened GPS Project

    National Aeronautics and Space Administration — A Communications, Navigation, and Networking reConfigurable Testbed (CoNNeCT) experiment is proposed to improve the performance of GPS during geomagnetic storms....

  8. SECURE TRACKING AND TRANSPORT SYSTEM USING RWP AND GPS

    Silky Verma

    2013-06-01

    Full Text Available In the present era where technology has become a part of our life, every day new applications are developed in every field to serve mankind. Many applications have been developed using GPS (globalpositioning system such as aquatic and spacecraft routing, surveying and mapping, precise time reference etc. GPS (global positioning system enables everyday activities such as banking, mobile phone operations, and even the control of power grids by allowing well harmonized hand-off switching and accurate time. The main contribution of this paper is tracking and transportation of object in a secured way using RWP and GPS. To assure the security of the tracking and tracing application we introduce a method to evaluate the one-hop distance between the target object and all the cooperative nodes in the object’s view. A key factor that increases the project’s accuracy and performance is GPS, a common example of wireless which can be interfaced to provide location and time information in all weather conditions. GPS has become a widely adopted and useful tool for commerce, scientific uses, tracking, and investigation. We control the ground session with RWP (random way point using AODV routing protocol. DOP (dilution of precision.

  9. GPS Auto-Navigation Design for Unmanned Air Vehicles

    Nilsson, Caroline C. A.; Heinzen, Stearns N.; Hall, Charles E., Jr.; Chokani, Ndaona

    2003-01-01

    A GPS auto-navigation system is designed for Unmanned Air Vehicles. The objective is to enable the air vehicle to be used as a test-bed for novel flow control concepts. The navigation system uses pre-programmed GPS waypoints. The actual GPS position, heading, and velocity are collected by the flight computer, a PC104 system running in Real-Time Linux, and compared with the desired waypoint. The navigator then determines the necessity of a heading correction and outputs the correction in the form of a commanded bank angle, for a level coordinated turn, to the controller system. This controller system consists of 5 controller! (pitch rate PID, yaw damper, bank angle PID, velocity hold, and altitude hold) designed for a closed loop non-linear aircraft model with linear aerodynamic coefficients. The ability and accuracy of using GPS data, is validated by a GPS flight. The autopilots are also validated in flight. The autopilot unit flight validations show that the designed autopilots function as designed. The aircraft model, generated on Matlab SIMULINK is also enhanced by the flight data to accurately represent the actual aircraft.

  10. Continuous professional development for GPs

    Kjaer, N K; Steenstrup, A P; Pedersen, L B;

    2014-01-01

    randomly chosen Danish GPs. RESULTS: Focus groups: CPD activities are chosen based on personal needs analysis, and in order to be professionally updated, to meet engaged colleagues and to prevent burnout. GPs also attend CPD to assess their own pre-existing level of competence. CPD activities need to be...... motivated by topics strengthening their professional capacity and preventing burnout. There would seem to be no need for a mandatory system....

  11. GPS Tracker Data Analysis Platform

    Belay, Tinbit

    2015-01-01

    This thesis work offers GPS tracking solutions which provides detailed reporting on the tracked assets while significantly reducing costs. Despite the fact that GPS trackers are used as a security mechanism. The objective of this thesis was to develop a web platform for gathering the be-havioral aspects of the tracked assets. The thesis work was designed and imple-mented using Groovy-based web application framework, which integrates smooth-ly with the JVM. The user interface was implement...

  12. A New Indoor Positioning System Architecture Using GPS Signals

    Rui Xu

    2015-04-01

    Full Text Available 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.

  13. Height Accuracy Based on Different Rtk GPS Method for Ultralight Aircraft Images

    Tahar, K. N.

    2015-08-01

    Height accuracy is one of the important elements in surveying work especially for control point's establishment which requires an accurate measurement. There are many methods can be used to acquire height value such as tacheometry, leveling and Global Positioning System (GPS). This study has investigated the effect on height accuracy based on different observations which are single based and network based GPS methods. The GPS network is acquired from the local network namely Iskandar network. This network has been setup to provide real-time correction data to rover GPS station while the single network is based on the known GPS station. Nine ground control points were established evenly at the study area. Each ground control points were observed about two and ten minutes. It was found that, the height accuracy give the different result for each observation.

  14. PosQ: Unsupervised Fingerprinting and Visualization of GPS Positioning Quality

    Kjærgaard, Mikkel Baun; Weckemann, Kay

    GPS positioning does not provide pervasive coverage and the accuracy depends on the local environment. When deploying and managing position-based applications it is important to know when to depend on GPS and when to deploy supplementary means of positioning, such as local or inertial positioning....... This paper proposes PosQ, a system for unsupervised fingerprinting and visualization of GPS positioning quality. PosQ provides quality maps to position-based applications and visual overlays to users and managers to reveal the positioning quality in a local environment. The system reveals the quality...... both as it changes over time, in 2D and 3D, and for each type of GPS receiver. Our evaluation provides evidence that the collected quality maps are accurate, that they remain informative over time, that they capture the differences among GPS receivers, and that they can be efficiently collected by...

  15. PosQ : Unsupervised Fingerprinting and Visualization of GPS Positioning Quality

    Kjærgaard, Mikkel Baun; Weckemann, Kay

    2010-01-01

    GPS positioning does not provide pervasive coverage and the accuracy depends on the local environment. When deploying and managing position-based applications it is important to know when to depend on GPS and when to deploy supplementary means of positioning, such as local or inertial positioning....... This paper proposes PosQ, a system for unsupervised fingerprinting and visualization of GPS positioning quality. PosQ provides quality maps to position-based applications and visual overlays to users and managers to reveal the positioning quality in a local environment. The system reveals the quality...... both as it changes over time, in 2D and 3D, and for each type of GPS receiver. Our evaluation provides evidence that the collected quality maps are accurate, that they remain informative over time, that they capture the differences among GPS receivers, and that they can be efficiently collected by...

  16. Operational aspects of CASA UNO '88-The first large scale international GPS geodetic network

    Neilan, Ruth E.; Dixon, T. H.; Meehan, Thomas K.; Melbourne, William G.; Scheid, John A.; Kellogg, J. N.; Stowell, J. L.

    1989-01-01

    For three weeks, from January 18 to February 5, 1988, scientists and engineers from 13 countries and 30 international agencies and institutions cooperated in the most extensive GPS (Global Positioning System) field campaign, and the largest geodynamics experiment, in the world to date. This collaborative eperiment concentrated GPS receivers in Central and South America. The predicted rates of motions are on the order of 5-10 cm/yr. Global coverage of GPS observations spanned 220 deg of longitude and 125 deg of latitude using a total of 43 GPS receivers. The experiment was the first civilian effort at implementing an extended international GPS satellite tracking network. Covariance analyses incorporating the extended tracking network predicted significant improvement in precise orbit determination, allowing accurate long-baseline geodesy in the science areas.

  17. PRINCIPLE, SOFTWARE AND EXPERIMENT OF GPS-SUPPORTED AEROTRIANGULATION

    2000-01-01

    In conventional aerial photogrammetry, the high accurate photogrammetric point determination is always carried out by aerotriangulation using a great deal of ground control points around the perimeter and in the center of block area because the exterior orien tation parameters of aerial photographs are unknown. A technological revolution in pho togrammetry has taken place since Navstar global positioning system (GPS) was applied to determine the 3D coordinates of exposure station positions during the photo flight missions. GPS-supported aerotriangulation is conducted by a combined bundle adjustment for pho togrammetric observations and the camera orientation data. In this case, the essential ground control points are replaced by GPS-determined camera positions. Recent investigations show this method is coming to the practice. We have been engaged in the theoretical studies, soft ware development,and related experiments and production in the field since 1990. So far the abundant research achievements are obtained in terms of the theory and application. In this paper, we first derives the mathematical model of GPS-supported aerotriangulation from the geometry between camera and airborne GPS antenna, then describes briefly a software pack age WuCAPS (Wuhan combined adjustment program system) developed newly by the au thor,which serves the purpose of the combined bundle adjustment for photogrammetric and non-photogrammetric observations. At the end of the present work, a set of actual aerial pho tographs,at the image scale of 1:34 000, with airborne GPS data taken from Tianjing site, China were processed by WuCAPS. The empirical results have verified that the accuracy of the combined bundle adjustment with 4 XYZ ground control points around the comers of block area is very close to that of the conventional bundle adjustment with 3 additional pa rameters, that leads to reduce 88% field survey and 75% production cost,and can meet the specification of topographic mapping

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

    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.

  19. GPS/INS Sensor Fusion Using GPS Wind up Model

    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.

  20. Precise GPS/GNSS Positioning Solution for Airborne Data Acquisition Systems

    B. G. Gerlach; D. Gondy

    2003-01-01

    The precise positioning of aircrafts during flights belongs to the great challenges with respect to the development of airborne data acquisition systems. Satellite positioning systems like GPS offers a unique capability for precise positioning but requires in depth knowledge of GPS in airborne applications, e.g.GPS for high dynamic application, integration of GPS with other sensors, dynamic behaviour of aircrafts or antenna location. For its positioning reference system of Flight Inspection systems Aerodata AG has developed a robust GPS carrier phase ambiguity solution P-DGPS, Precise Differential GPS combined with complementary sensors like INS, barometers, radio altimeters or laser altimeters as well as laser trackers. Using recorded data during the flight the algorithm offers also the capability to calculate more accurate positions in post-processing. The presented sensor fusion algorithm using GPS without differential corrections (SGPS, standalone GPS) offers a precise height reference solution for approach calibration based only on aircraft-based sensors. SGPS data are combined in post-processing with inertial, pressure, radio and laser altimeter data. Flight trials with a Bombardier "Global Express" at Braunschweig Airport on May 2002 shows the achieved accuracies of the height reference solution calculated by SGPS in comparison to P-DGPS. The SGPS solution for precise height calculation of special mission aircrafts provides accuracies in the order of 5 m and at the runway's threshold in the order of 30 cm.

  1. GPS derived Crustal Deformation and Strain determination in India

    Abhay P. Singh,

    2011-06-01

    Full Text Available The theory of Plate tectonics has revolutionized the way thinking about the processes of Earth. According to this theory, the surface of the Earth is broken into large plates. The size and position of these plates change over time. The edges of these plates, where they move against each other, are sites of intense tectonic activity, suchas earthquakes, volcanism, and mountain building. It is well known that Indian Plate is currently moving in the northeast direction, while the Eurasian Plate is moving north. This is causing the Indian and Eurasian Plate to deform at the point of contact besides its interior. Modern geophysical and space geodetic techniques such asseismology and GPS (Global Positioning system, have become important tools in the study of the deformation in the Earth due to tectonic processes, leading to earthquakes. Geodesy has provided an important role for plate tectonics study with high temporal resolution of the plate movements, particular from space technologies such as GPS and VLBI. The Global Positioning System (GPS provides accurate measurements of the rate of displacement of crustal. Indeed, the GPS velocity field can only be compared to finite strain if one assumes adeformation mechanism and that the style of deformation has been the same over long periods of geological time. For study of crustal deformation National Center of Mineralogy and Petrology, University of Allahabad, Allahabad installed highly efficient and accurate LEICA GRX1200 Pro receiver at Ghoorpur near to Allahabad. This instrument is also equipped withMET3A sensor to record pressure, temperature, humidity at regular interval of 30 second. The Latitude and longitude of the GPS sites is 25.21N, 81.28E.

  2. Inversion of GPS meteorology data

    K. Hocke

    Full Text Available The GPS meteorology (GPS/MET experiment, led by the Universities Corporation for Atmospheric Research (UCAR, consists of a GPS receiver aboard a low earth orbit (LEO satellite which was launched on 3 April 1995. During a radio occultation the LEO satellite rises or sets relative to one of the 24 GPS satellites at the Earth's horizon. Thereby the atmospheric layers are successively sounded by radio waves which propagate from the GPS satellite to the LEO satellite. From the observed phase path increases, which are due to refraction of the radio waves by the ionosphere and the neutral atmosphere, the atmospheric parameter refractivity, density, pressure and temperature are calculated with high accuracy and resolution (0.5–1.5 km. In the present study, practical aspects of the GPS/MET data analysis are discussed. The retrieval is based on the Abelian integral inversion of the atmospheric bending angle profile into the refractivity index profile. The problem of the upper boundary condition of the Abelian integral is described by examples. The statistical optimization approach which is applied to the data above 40 km and the use of topside bending angle profiles from model atmospheres stabilize the inversion. The retrieved temperature profiles are compared with corresponding profiles which have already been calculated by scientists of UCAR and Jet Propulsion Laboratory (JPL, using Abelian integral inversion too. The comparison shows that in some cases large differences occur (5 K and more. This is probably due to different treatment of the upper boundary condition, data runaways and noise. Several temperature profiles with wavelike structures at tropospheric and stratospheric heights are shown. While the periodic structures at upper stratospheric heights could be caused by residual errors of the ionospheric correction method, the periodic temperature fluctuations at heights below 30 km are most likely caused by atmospheric waves (vertically

  3. GPS Attitude Determination for Launch Vehicles Project

    National Aeronautics and Space Administration — Toyon Research Corporation proposes to develop a family of compact, low-cost GPS-based attitude (GPS/A) sensors for launch vehicles. In order to obtain 3-D attitude...

  4. Location - Global Positioning System (GPS) Photos

    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...

  5. GPS operations at Olkiluoto in 2011

    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

  6. Evaluating GPS Data in Indoor Environments

    MOTTE, H.; WYFFELS, J.; Strycker, L.; GOEMAERE, J.-P.

    2011-01-01

    With the latest generation of ultra-sensitive GPS-receivers, satellite signals can often be picked up even indoors, resulting in (inaccurate) indoor GPS-localization. A covered position will therefore no longer be characterized by the absence of satellite signals, creating the need for another way of categorizing this data as potentially inaccurate. This paper describes the use of GPS-based localization in an indoor environment. Only high level, generally available, GPS-data (NMEA-0183 GN...

  7. Reprocessed height time series for GPS stations

    S. Rudenko; Schön, N.; Uhlemann, M; G. Gendt

    2013-01-01

    Precise weekly positions of 403 Global Positioning System (GPS) stations located worldwide are obtained by reprocessing GPS data of these stations for the time span from 4 January 1998 until 29 December 2007. The processing algorithms and models used as well as the solution and results obtained are presented. Vertical velocities of 266 GPS stations having a tracking history longer than 2.5 yr are computed; 107 of them are GPS stations located at tide gauges (TIGA observing stations). The vert...

  8. Terrain modelling by kinematical GPS survey

    Nico, G.; P. Rutigliano; Benedetto, C.; F. Vespe

    2005-01-01

    This work presents the first results of an experiment aiming to derive a high resolution Digital Terrain Model (DTM) by kinematic GPS surveying. The accuracy of the DTM depends on both the operational GPS precision and the density of GPS samples. The operational GPS precision, measured in the field, is about 10cm. A Monte Carlo analysis is performed to study the dependence of the DTM error on the sampling procedure. The outcome of this analysis is that the accuracy of the to...

  9. High precision inter-continental GPS network

    Monico, João Francisco Galera

    1995-01-01

    GPS relative positioning provides precision of the order of 1 part per million (ppm) within relatively short periods of time. Considering this level of precision, together with the fact that the cost of GPS receivers is continuing come down, it is now apparent that most of the future geodetic surveys will be performed by GPS, It is therefore important to establish geodetic control networks which are suitable for geodetic GPS activities. The Brazilian Institute of Geography and Statistics (IBG...

  10. Retrieving real-time co-seismic displacements using GPS/GLONASS: a preliminary report from the September 2015 Mw 8.3 Illapel earthquake in Chile

    Chen, Kejie; Ge, Maorong; Babeyko, Andrey; Li, Xingxing; Diao, Faqi; Tu, Rui

    2016-08-01

    Compared with a single GPS system, GPS/GLONASS observations can improve the satellite visibility, optimize the spatial geometry and improve the precise positioning performance. Although the advantage over GPS-only methods in terms of positioning is clear, the potential contributions of GPS/GLONASS to co-seismic displacement determination and the subsequent seismic source inversion still require extensive study and validation. In this paper, we first extended a temporal point positioning model from GPS-only to GPS/GLONASS observations. Using this new model, the performance of the GPS/GLONASS method for obtaining co-seismic displacements was then validated via eight outdoor experiments on a shaking table. Our result reveals that the GPS/GLONASS method provides more accurate and robust co-seismic displacements than the GPS-only observations in a non-optimal observation environment. Furthermore, as a case study, observation data recorded during the September 2015 Mw 8.3 Illapel earthquake in Chile were re-processed. At some stations, obvious biases were found between the co-seismic displacements derived from GPS-only and GPS/GLONASS observations. The subsequent slip distribution inversion on a curved fault confirms that the differences in the co-seismic displacements causes differences in the inversion results and that the slip distributions of the Illapel earthquake inferred from the GPS/GLONASS observations tend to be shallower and larger.

  11. Real-time retrieval of precipitable water vapor from GPS and BeiDou observations

    Lu, Cuixian; Li, Xingxing; Nilsson, Tobias; Ning, Tong; Heinkelmann, Robert; Ge, Maorong; Glaser, Susanne; Schuh, Harald

    2015-09-01

    The rapid development of the Chinese BeiDou Navigation Satellite System (BDS) brings a promising prospect for the real-time retrieval of zenith tropospheric delays (ZTD) and precipitable water vapor (PWV), which is of great benefit for supporting the time-critical meteorological applications such as nowcasting or severe weather event monitoring. In this study, we develop a real-time ZTD/PWV processing method based on Global Positioning System (GPS) and BDS observations. The performance of ZTD and PWV derived from BDS observations using real-time precise point positioning (PPP) technique is carefully investigated. The contribution of combining BDS and GPS for ZTD/PWV retrieving is evaluated as well. GPS and BDS observations of a half-year period for 40 globally distributed stations from the International GNSS Service Multi-GNSS Experiment and BeiDou Experiment Tracking Network are processed. The results show that the real-time BDS-only ZTD series agree well with the GPS-only ZTD series in general: the RMS values are about 11-16 mm (about 2-3 mm in PWV). Furthermore, the real-time ZTD derived from GPS-only, BDS-only, and GPS/BDS combined solutions are compared with those derived from the Very Long Baseline Interferometry. The comparisons show that the BDS can contribute to real-time meteorological applications, slightly less accurately than GPS. More accurate and reliable water vapor estimates, about 1.3-1.8 mm in PWV, can be obtained if the BDS observations are combined with the GPS observations in the real-time PPP data processing. The PWV comparisons with radiosondes further confirm the performance of BDS-derived real-time PWV and the benefit of adding BDS to standard GPS processing.

  12. Managing the GPS/GIS function in an electric utility

    A new period of higher significance has arrived for the GPS/GIS function at electric utilities such that to a degree never seen before, utility managers are looking to their GIS programs, filled with increasingly accurate data collected by GPS technology, before making many decisions. With this capability comes an expectation for GPS/GIS professionals to provide higher levels of planning and management of their data collection process. At Duke Power in Charlotte, North Carolina, managers rely on GPS mapping to fill their data collection equipment needs. When the city of Charlotte requested a more detailed billing system, Duke Power co-sponsored the street lighting inventory project, a comprehensive program implemented to fully account for street lighting facilities within the billing area. One of the key projects to be kept in mind was the creation of a common data base viewable by GIS from which a bill could be created and as well reveal data. A billing calculation routine can be run against the data base to generate a bill or use MapInfo to see a graphical picture. Prior to the creation of this data base capability, the difference between the data base as a display tool and billing system was a potential source of discrepancy, which is eliminated now. Creating the data base allows more than just creating a bill for the city, it allows Duke Power to work better with the city by improving its billing accountability and provides better service as well

  13. GPS orbit determination at the National Geodetic Survey

    Schenewerk, Mark S.

    1992-01-01

    The National Geodetic Survey (NGS) independently generates precise ephemerides for all available Global Positioning System (GPS) satellites. Beginning in 1991, these ephemerides were produced from double-differenced phase observations solely from the Cooperative International GPS Network (CIGNET) tracking sites. The double-difference technique combines simultaneous observations of two satellites from two ground stations effectively eliminating satellite and ground receiver clock errors, and the Selective Availability (S/A) signal degradation currently in effect. CIGNET is a global GPS tracking network whose primary purpose is to provide data for orbit production. The CIGNET data are collected daily at NGS and are available to the public. Each ephemeris covers a single week and is available within one month after the data were taken. Verification is by baseline repeatability and direct comparison with other ephemerides. Typically, an ephemeris is accurate at a few parts in 10(exp 7). This corresponds to a 10 meter error in the reported satellite positions. NGS is actively investigating methods to improve the accuracy of its orbits, the ultimate goal being one part in 10(exp 8) or better. The ephemerides are generally available to the public through the Coast Guard GPS Information Center or directly from NGS through the Geodetic Information Service. An overview of the techniques and software used in orbit generation will be given, the current status of CIGNET will be described, and a summary of the ephemeris verification results will be presented.

  14. Exploring GPS Data for Operational Analysis of Farm Machinery

    Ramin Shamshiri

    2013-04-01

    Full Text Available Global Positioning System (GPS has made a great evolution in different aspects of modern agricultural sectors. Today, a growing number of crop producers are using GPS and other modern electronic and computer equipments to practice Site Specific Management (SSM and precision agriculture. This technology has the potential in agricultural mechanization by providing farmers with a sophisticated tool to measure yield on much smaller scales as well as precisely determination and automatic storing of variables such as field time, working area, machine travel distance and speed, fuel consumption and yield information. This study focuses on how to interpret and process raw GPS data for operational analysis of farm machinery. Exact determinations of field activities using GPS data along with accurate measurements and records of yield provide an integrated tool to calculate field efficiency and field machine index which in turn increases machine productivity and labor saving. The results can also provide graphical tools for visualizing machine operator’s performance as well as making decision on field and machine size and selection.

  15. IMU/GPS System Provides Position and Attitude Data

    Lin, Ching Fang

    2006-01-01

    A special navigation system is being developed to provide high-quality information on the position and attitude of a moving platform (an aircraft or spacecraft), for use in pointing and stabilization of a hyperspectral remote-sensing system carried aboard the platform. The system also serves to enable synchronization and interpretation of readouts of all onboard sensors. The heart of the system is a commercially available unit, small enough to be held in one hand, that contains an integral combination of an inertial measurement unit (IMU) of the microelectromechanical systems (MEMS) type, Global Positioning System (GPS) receivers, a differential GPS subsystem, and ancillary data-processing subsystems. The system utilizes GPS carrier-phase measurements to generate time data plus highly accurate and continuous data on the position, attitude, rotation, and acceleration of the platform. Relative to prior navigation systems based on IMU and GPS subsystems, this system is smaller, is less expensive, and performs better. Optionally, the system can easily be connected to a laptop computer for demonstration and evaluation. In addition to airborne and spaceborne remote-sensing applications, there are numerous potential terrestrial sensing, measurement, and navigation applications in diverse endeavors that include forestry, environmental monitoring, agriculture, mining, and robotics.

  16. Recent GPS Results at SLAC

    The Alignment Engineering Group (AEG) makes use of GPS technology for fulfilling part of its above ground surveying tasks at SLAC since early 2002. A base station (SLAC M40) has been set up at a central location of the SLAC campus serving both as master station for real-time kinematic (RTK) operations and as datum point for local GPS campaigns. The Leica RS500 system is running continuously and the GPS data are collected both externally (logging PC) and internally (receiver flashcard). The external logging is facilitated by a serial to Ethernet converter and an Ethernet connection at the station. Internal logging (ring buffer) is done for data security purposes. The weatherproof boxes for the instrumentation are excellent shelters against rain and wind, but do heat up considerably in sun light. Whereas the GPS receiver showed no problems, the Pacific Crest PDL 35 radio shut down several times due to overheating disrupting the RTK operations. In order to prevent heat-induced shutdowns, a protection against direct sun exposure (shading) and a constant air circulation system (ventilation) were installed. As no further shutdowns have occurred so far, it appears that the two measures successfully mended the heat problem

  17. Animal Tracking ARGOS vs GPS

    Robinson, P. W.; Costa, D.; Arnould, J.; Weise, M.; Kuhn, C.; Simmons, S. E.; Villegas, S.; Tremblay, Y.

    2006-12-01

    ARGOS satellite tracking technology has enabled a tremendous increase in our understanding of the movement patterns of a diverse array of marine vertebrates from Sharks to marine mammals. Our current understanding has moved from simple descriptions of large scale migratory patterns to much more sophisticated comparisons of animal movements and behavior relative to oceanic features. Further, animals are increasingly used to carry sensors that can acquire water column temperature and salinity profiles. However, a major limitation of this work is the spatial precision of ARGOS locations. ARGOS provides 7 location qualities that range from 3,2,1,0,A,B,Z and correspond to locations with a precision of 150m to tens of kilometers. Until recently, GPS technology could not be effectively used with marine mammals because they did not spend sufficient time at the surface to allow complete acquisition of satellite information. The recent development of Fastloc technology has allowed the development of GPS tags that can be deployed on marine mammals. Here we compare the location quality and frequency derived from standard ARGOS PTTs to Fastloc GPS locations acquired from 11 northern elephant seals, 5 California and 5 Galapagos sea lions and 1 Cape and 3 Australian fur seals. Our results indicate that GPS technology will greatly enhance our ability to understand the movement patterns of marine vertebrates and the in-situ oceanographic data they collect.

  18. NASA's global differential GPS system and the TDRSS augmentation service for satellites

    Bar-Sever, Yoaz; Young, Larry; Stocklin, Frank; Rush, John

    2004-01-01

    NASA is planning to launch a new service for Earth satellites providing them with precise GPS differential corrections and other ancillary information enabling decimeter level orbit determination accuracy, and nanosecond time-transfer accuracy, onboard, in real-time. The TDRSS Augmentation Service for Satellites (TASS) will broadcast its message on the S-band multiple access channel of NASA's Tracking and Data Relay Satellite System (TDRSS). The satellite's phase array antenna has been configured to provide a wide beam, extending coverage up to 1000 km altitude over the poles. Global coverage will be ensured with broadcast from three or more TDRSS satellites. The GPS differential corrections are provided by the NASA Global Differential GPS (GDGPS) System, developed and operated by NASA's Jet Propulsion Laboratory. The GDGPS System employs a global ground network of more than 70 GPS receivers to monitor the GPS constellation in real time. The system provides real-time estimates of the GPS satellite states, as well as many other real-time products such as differential corrections, global ionospheric maps, and integrity monitoring. The unique multiply redundant architecture of the GDGPS System ensures very high reliability, with 99.999% demonstrated since the inception of the system in Early 2000. The estimated real time GPS orbit and clock states provided by the GDGPS system are accurate to better than 20 cm 3D RMS, and have been demonstrated to support sub-decimeter real time positioning and orbit determination for a variety of terrestrial, airborne, and spaceborne applications. In addition to the GPS differential corrections, TASS will provide real-time Earth orientation and solar flux information that enable precise onboard knowledge of the Earth-fixed position of the spacecraft, and precise orbit prediction and planning capabilities. TASS will also provide 5 seconds alarms for GPS integrity failures based on the unique GPS integrity monitoring service of the

  19. Altimetry Using GPS-Reflection/Occultation Interferometry

    Cardellach, Estel; DeLaTorre, Manuel; Hajj, George A.; Ao, Chi

    2008-01-01

    A Global Positioning System (GPS)- reflection/occultation interferometry was examined as a means of altimetry of water and ice surfaces in polar regions. In GPS-reflection/occultation interferometry, a GPS receiver aboard a satellite in a low orbit around the Earth is used to determine the temporally varying carrier- phase delay between (1) one component of a signal from a GPS transmitter propagating directly through the atmosphere just as the GPS transmitter falls below the horizon and (2) another component of the same signal, propagating along a slightly different path, reflected at glancing incidence upon the water or ice surface.

  20. Simulation and analysis of differential GPS

    Denaro, R. P.

    NASA is conducting a research program to evaluate differential Global Positioning System (GPS) concepts for civil helicopter navigation. It is pointed out that the civil helicopter community will probably be an early user of GPS because of the unique mission operations in areas where precise navigation aids are not available. However, many of these applications involve accuracy requirements which cannot be satisfied by conventional GPS. Such applications include remote area search and rescue, offshore oil platform approach, remote area precision landing, and other precise navigation operations. Differential GPS provides a promising approach for meeting very demanding accuracy requirements. The considered procedure eliminates some of the common bias errors experienced by conventional GPS. This is done by making use of a second GPS receiver. A simulation process is developed as a tool for analyzing various scenarios of GPS-referenced civil aircraft navigation.

  1. Experimental validation of GPS-INS-STAR hybrid navigation system for space autonomy

    Tanabe, Toru; Harigae, Masatoshi

    The experimental validation of the GPS-INS-STAR hybrid navigation system concept is performed. The hybrid navigation system combines the best features of employed sensors to improve total navigation performances. The GPS-INS-STAR hybrid navigation system consists of the three different sensors, a GPS receiver, an inertial navigation system and a STAR image sensor. In this concept, the system integrates a high positioning performance of the GPS system, an accurate attitude determination capability of the STAR image sensor and the INS signal with a wide bandwidth. It results in a complete 6-DOF (degrees of freedom) autonomous navigation system. The present paper shows the validation of the concept by the experiments using GPS, INS and STAR hardware systems. The experiments are divided into three steps. Firstly, the INS-STAR hybrid navigation system is constructed on the 3-axis motion table to verify the performances of its attitude loop. Secondly, the GPS-INS hybrid navigation system installed on the car shows the performance improvement in its translational loop. Finally, the full configuration of the GPS-INS-STAR hybrid navigation system is evaluated at night. Each experiment result is checked by the theoretical analysis. In the theoretical analysis, the concept of observability well explains the performances of the system. Its feasibility for space application is also evaluated in the point of existing hardware technology. It is concluded that the experiments vaidate the concept of the hybrid navigation system and confirm its capability to realize space autonomy.

  2. Reinforced Ultra-Tightly Coupled GPS/INS System for Challenging Environment

    Xueyun Wang

    2014-01-01

    Full Text Available Among all integration levels currently available for Global Positioning System (GPS and Inertial Navigation System (INS Integrated System, ultra-tightly coupled (UTC GPS/INS system is the best choice for accurate and reliable navigation. Nevertheless the performance of UTC GPS/INS system degrades in challenging environments, such as jamming, changing noise of GPS signals, and high dynamic maneuvers. When low-end Inertial Measurement Units (IMUs based on MEMS sensors are employed, the performance degradation will be more severe. To solve this problem, a reinforced UTC GPS/INS system is proposed. Two techniques are adopted to deal with jamming and high dynamics. Firstly, adaptive integration Kalman filter (IKF based on fuzzy logics is developed to reinforce the antijamming ability. The parameters of membership functions (MFs are adjusted and optimized through self-developed neutral network. Secondly, a Doppler frequency error estimator based on Kalman filter is designed to improve the navigation performance under high dynamics. A complete simulation platform is established to evaluate the reinforced system. Results demonstrate that the proposed system architecture significantly improves navigation performance in challenging environments and it is a more advanced solution to accurate and reliable navigation than traditional UTC GPS/INS system.

  3. Image Network Generation of Uncalibrated Uav Images with Low-Cost GPS Data

    Huang, Shan; Zhang, Zuxun; He, Jianan; Ke, Tao

    2016-06-01

    The use of unmanned air vehicle (UAV) images acquired by a non-metric digital camera to establish an image network is difficult in cases without accurate camera model parameters. Although an image network can be generated by continuously calculating camera model parameters during data processing as an incremental structure from motion (SfM) methods, the process is time consuming. In this study, low-cost global position system (GPS) information is employed in image network generation to decrease computational expenses. Each image is considered as reference, and its neighbor images are determined based on GPS coordinates during processing. The reference image and its neighbor images constitute an image group, which is used to generate a free network through image matching and relative orientation. Data are then transformed from the free network coordinate system of each group into the GPS coordinate system by using the GPS coordinates of each image. After the exterior elements of each image are determined in the GPS coordinate system, the initial image network is established. Finally, self-calibration bundle adjustment constrained by GPS coordinates is conducted to refine the image network. The proposed method is validated on three fields. Results confirm that the method can achieve good image network when accurate camera model parameters are unavailable.

  4. Rip current monitoring using GPS buoy system

    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

  5. Instant tsunami early warning based on real-time GPS – Tohoku 2011 case study

    A. Hoechner

    2013-05-01

    Full Text Available Taking the 2011 Tohoku earthquake as an example, we demonstrate the ability of real-time GPS to provide qualified tsunami early warning within minutes. While in earlier studies we demonstrated the power of the so-called GPS shield concept based on synthetic data, we here present a complete processing chain starting from actual GPS raw data and fully simulate the situation as it would be in a warning center. The procedure includes processing of GPS observations with predicted high precision orbits, inversion for slip and computation of the tsunami propagation and coastal warning levels. We show that in case of the Tohoku earthquake, it would be feasible to provide accurate tsunami warning as soon as 3 min after the beginning of the earthquake.

  6. Thermal structure of intense convective clouds derived from GPS radio occultations

    R. Biondi

    2011-10-01

    Full Text Available 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 occultations with CALIPSO profiles over deep convection. Results show a sharp spike in GPS bending angle highly correlated to the top of the clouds, corresponding to anomalously cold temperatures within the clouds. Above the clouds the temperatures return to background conditions, and there is a strong inversion at cloud top. For cloud tops below 14 km, the temperature lapse rate within the cloud often approaches a moist adiabat, consistent with rapid undiluted ascent within the convective systems.

  7. Simulation and acquisition of gps l5 frequency signal and comparison with l1 signal

    Recent advances in GPS modernization efforts include transmission of L5 frequency signals. This paper emphasizes on the implementation of acquisition techniques for GPS L5 and GPS L1 signals. Both signals have been simulated and analysed in a detailed manner to obtain better acquisition results. In this context the signals have been generated, transmitted, received and acquired by suitable algorithms. Simulations were performed using Borland C++ Builder Compiler and MATLAB softwares. Results reveal that L5 signal offers many advantages, including that the acquisition peaks are more accurate, dominant and wider as compared to L1 signal, thus improving GPS system overall performance. Moreover, L5 signals reduce vulnerability to waveform deformation. Noise levels are also comparatively lower than previous signals. (author)

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

    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.

  9. Global optimization applied to GPS positioning by ambiguity functions

    Differential GPS positioning with carrier-phase observables is commonly done in a process that involves determination of the unknown integer ambiguity values. An alternative approach, named the ambiguity function method, was already proposed in the early days of GPS positioning. By making use of a trigonometric function ambiguity unknowns are eliminated from the functional model before the estimation process. This approach has significant advantages, such as ease of use and insensitivity to cycle slips, but requires such high accuracy in the initial approximate coordinates that its use has been practically dismissed from consideration. In this paper a novel strategy is proposed so that the need for highly accurate initial coordinates disappears: the application of a global optimization method to the ambiguity functions model. The use of this strategy enables the ambiguity function method to compete with the present prevailing approach of ambiguity resolution

  10. GPS Multipath in Urban Environments

    Bilich, A.; Sella, G.

    2008-12-01

    Multipath, where a GNSS signal arrives by more than one path, is considered one of the last unmodeled errors remaining in GNSS. Multipath is of great concern because the additional path length traveled by the incoming signal biases the satellite-receiver range and therefore determination of position. Siting a GNSS station in an urban area, in the immediate vicinity of large reflecting objects such as rooftops, buildings, asphalt and concrete parking lots, grassy fields, and chainlink fences, is both a multipath nightmare and a necessary evil. We note that continuously-operating GNSS stations are becoming increasingly common in urban areas, which makes sense as these stations are often installed in support of civil infrastructure (e.g. departments of transportation, strong motion monitoring of buildings in earthquake-prone areas, surveying networks). Urban stations are well represented in geodetic networks such as the CORS (United States) and GeoNet (Japan) networks, with more stations likely to be installed in the coming years. What sources and types of urban multipath are the most detrimental to geodetic GPS positioning? Which reflecting objects are assumed to be a major source of multipath error, but the GPS data show otherwise? Are certain reflecting environments worse for specific applications, i.e. kinematic vs. static positioning? If forced to install a GNSS station in a highly reflective environment, is it possible to rank objects for their multipath severity? To answer these questions, we provide multipath examples taken from continuously- operating GNSS stations sited in urban environments. We concentrate on some of the most common obstacles and reflecting objects for urban sites - rooftops, parking lots, and fences. We analyze the multipath signature of these objects as manifested in the GPS phase, pseudorange, and signal-to-noise ratio (SNR) observables, and also examine multipath impacts on the precision and accuracy of GPS-derived positions.

  11. Inappropriate circumcision referrals by GPs.

    Griffiths, D.; Frank, J D

    1992-01-01

    One hundred and twenty boys were referred by GPs over a 12-month period to a paediatric urologist for circumcision. The reasons for referral were: ballooning in 36, non-retraction in 28, balanoposthitis in 36 or a combination in 15. On examination 53% had a retractile, 21% a partially retractile and 21% a non-retractile foreskin. Six patients had obvious balanitis xerotica obliterans. Only one quarter of the patients required a circumcision. The penis was not examined by the referring doctor ...

  12. GPS observables in general relativity

    I present a complete set of gauge invariant observables, in the context of general relativity coupled with a minimal amount of realistic matter (four particles). These observables have a straightforward and realistic physical interpretation. In fact, the technology to measure them is realized by the Global Positioning System: they are defined by the physical reference system determined by GPS readings. The components of the metric tensor in this physical reference system are gauge invariant quantities and, remarkably, their evolution equations are local

  13. GPS deformation measurements at Olkiluoto in 2013

    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

  14. GPS in Travel and Activity Surveys

    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 in the...... 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...

  15. Miniaturized GPS/MEMS IMU integrated board

    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.

  16. The estimation method of GPS instrumental biases

    2001-01-01

    A model of estimating the global positioning system (GPS) instrumental biases and the methods to calculate the relative instrumental biases of satellite and receiver are presented. The calculated results of GPS instrumental biases, the relative instrumental biases of satellite and receiver, and total electron content (TEC) are also shown. Finally, the stability of GPS instrumental biases as well as that of satellite and receiver instrumental biases are evaluated, indicating that they are very stable during a period of two months and a half.

  17. GPS operations at Olkiluoto in 2009

    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

  18. Evaluating GPS Data in Indoor Environments

    MOTTE, H.

    2011-08-01

    Full Text Available With the latest generation of ultra-sensitive GPS-receivers, satellite signals can often be picked up even indoors, resulting in (inaccurate indoor GPS-localization. A covered position will therefore no longer be characterized by the absence of satellite signals, creating the need for another way of categorizing this data as potentially inaccurate. This paper describes the use of GPS-based localization in an indoor environment. Only high level, generally available, GPS-data (NMEA-0183 GNSS-subset are taken into account. Applications of ubiquitous location awareness, where the use of several RTLS (Real Time Location System combinations is feasible, may benefit from this information to discriminate between GPS and other available localization data. A quality indicating parameter is readily available in GPS-data; the DOP (Dilution Of Precision data field, which indicates the accuracy of the GPS localization based on the current satellite geometry. However since in indoor environments the roof and possible overlying floors often cause more signal attenuation compared to (outer walls or windows, the probability of a better reception of 'low' orbiting satellite signals increases, giving rise to an unjustified good horizontal DOP value. Standard NMEA-0183 GPS strings are therefore analyzed in search of other indicators for malicious GPS-data.

  19. The GPS Laser Retroreflector Array Project

    Merkowitz, Stephen M.

    2012-01-01

    Systematic co-location in space through the precision orbit determination of GPS satellites via satellite laser ranging will contribute significantly towards improving the accuracy and stability of the international terrestrial reference frame. NASA recently formed the GPS Laser Retroreflector Array Project to develop and deliver retroreflectors for integration on the next generation of GPS satellites. These retroreflectors will be an important contributor to achieving a global accuracy of 1.0 mm and 0.1 mm/year stability in the international terrestrial reference frame. We report here the current status of the GPS Laser Retroreflector Array Project.

  20. GPS operations at Olkiluoto in 2009

    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

  1. Gravity field models derived from Swarm GPS data

    de Teixeira da Encarnação, João; Arnold, Daniel; Bezděk, Aleš; Dahle, Christoph; Doornbos, Eelco; van den IJssel, Jose; Jäggi, Adrian; Mayer-Gürr, Torsten; Sebera, Josef; Visser, Pieter; Zehentner, Norbert

    2016-04-01

    The GPS instruments on-board the three Earth's Magnetic Field and Environment Explorer (Swarm) satellites provide the opportunity to measure the gravity field model at basin-wide spatial scales. In spite of being a geo-magnetic satellite mission, Swarm's GPS receiver collects highly accurate hl-SST data (van den IJssel et al., 2015), which has been exploited to produce gravity field models at a number of institutes, namely at the Astronomical Institute (ASU) of the Czech Academy of Sciences (Bezděk et al., 2014), the Astronomical Institute of the University of Bern (AIUB, Jäggi et al., 2015) and the Institute of Geodesy (IfG) of the Graz University of Technology (Zehentner et al., 2015). With the help of GRACE gravity field models, which are derived from much more accurate ll-SST data, we investigate the best combination strategy for producing a superior model on the basis of the solutions produced by the three institutes, similarly to the approach taken by the European Gravity Service for Improved Emergency Management project (http://egsiem.eu). We demonstrate that the Swarm-derived gravity field models are able to resolve monthly solutions with 1666km spatial resolutions (roughly up to degree 12). We illustrate how these monthly solutions correlate with GRACE-derived monthly solutions, for the period of 2014 - 2015, as well as indicate which geographical areas are measured more or less accurately.

  2. Experimentos GPS con estaciones virtuales

    Afailal, Sara; Rueda Galcerán, José Diego

    2016-01-01

    En múltiples ocasiones aceptamos como correcta la información nominal que aparece en los manuales de los fabricantes de receptores GPS. En esta información nos muestran una precisión esperable a la hora de obtener resultados, siguiendo ciertos métodos de observación en ciertas condiciones. Teniendo en cuenta que los datos los procesamos con un software de cálculo de vectores, que a su vez tiene también una precisión esperable, hemos querido hacer una serie de experimentos desde estaciones vir...

  3. Do GPs' medical records demonstrate a good recognition of depression? A new perspective on case extraction.

    Joling, K.J.; Marwijk, H.W.J. van; Piek, E.; Horst, H.E. van der; Penninx, B.W.; Verhaak, P.; Hout, H.P.J. van

    2011-01-01

    Background: Previous estimates of depression recognition in primary care are low and inconsistent. This may be due to registration artifacts and limited extraction efforts. This study investigated a) whether GPs' medical records demonstrate an accurate recognition of depression and b) which combinat

  4. Do GPs' medical records demonstrate a good recognition of depression? A new perspective on case extraction

    Joling, Karlijn J.; van Marwijk, Harm W. J.; Piek, Ellen; van der Horst, Henriette E.; Penninx, Brenda W.; Verhaak, Peter; van Hout, Hein P. J.

    2011-01-01

    Background: Previous estimates of depression recognition in primary care are low and inconsistent. This may be due to registration artifacts and limited extraction efforts. This study investigated a) whether GPs' medical records demonstrate an accurate recognition of depression and b) which combinat

  5. Vision-GPS Fusion for Guidance of an Autonomous Vehicle in Row Crops

    Bak, Thomas

    2001-01-01

    generation is thus controlled by location relative to the local field while the actual path execution is carried out in absolute GPS coordinates. The solution is a system that fuse data from a relative and an absolute measurement system while ensuring accurate row operation at high work rates....

  6. Tropical cyclone cloud‐top height and vertical temperature structure detection using GPS radio occultation measurements

    Biondi, Riccardo; Ho, Shu‐Peng; Randel, William;

    2013-01-01

    The accurate determination of tropical cyclone (TC) cloud-top height and its vertical thermal structure using the GPS radio occultation (RO) technique is demonstrated in this study. Cloud-top heights are determined by using the bending angle anomaly and the temperature anomaly profiles during the...

  7. GPS time series at Campi Flegrei caldera (2000-2013

    Prospero De Martino

    2014-05-01

    Full Text Available The Campi Flegrei caldera is an active volcanic system associated to a high volcanic risk, and represents a well known and peculiar example of ground deformations (bradyseism, characterized by intense uplift periods, followed by subsidence phases with some episodic superimposed mini-uplifts. Ground deformation is an important volcanic precursor, and, its continuous monitoring, is one of the main tool for short time forecast of eruptive activity. This paper provides an overview of the continuous GPS monitoring of the Campi Flegrei caldera from January 2000 to July 2013, including network operations, data recording and processing, and data products. In this period the GPS time series allowed continuous and accurate tracking of ground deformation of the area. Seven main uplift episodes were detected, and during each uplift period, the recurrent horizontal displacement pattern, radial from the “caldera center”, suggests no significant change in deformation source geometry and location occurs. The complete archive of GPS time series at Campi Flegrei area is reported in the Supplementary materials. These data can be usefull for the scientific community in improving the research on Campi Flegrei caldera dynamic and hazard assessment.

  8. GPS Attitude Determination Using Deployable-Mounted Antennas

    Osborne, Michael L.; Tolson, Robert H.

    1996-01-01

    The primary objective of this investigation is to develop a method to solve for spacecraft attitude in the presence of potential incomplete antenna deployment. Most research on the use of the Global Positioning System (GPS) in attitude determination has assumed that the antenna baselines are known to less than 5 centimeters, or one quarter of the GPS signal wavelength. However, if the GPS antennas are mounted on a deployable fixture such as a solar panel, the actual antenna positions will not necessarily be within 5 cm of nominal. Incomplete antenna deployment could cause the baselines to be grossly in error, perhaps by as much as a meter. Overcoming this large uncertainty in order to accurately determine attitude is the focus of this study. To this end, a two-step solution method is proposed. The first step uses a least-squares estimate of the baselines to geometrically calculate the deployment angle errors of the solar panels. For the spacecraft under investigation, the first step determines the baselines to 3-4 cm with 4-8 minutes of data. A Kalman filter is then used to complete the attitude determination process, resulting in typical attitude errors of 0.50.

  9. Tectonic motions and earthquake deformation in Greece from GPS measurements

    Clarke, Peter John; Parsons, Barry Eaton; England, Philip Christopher

    1996-01-01

    Sites in a 66-station geodetic network in central Greece have been occupied up to six times since 1989 using GPS surveying, and accurate positions have been computed using fiducially-improved or precise orbits. Site velocities are calculated under the assumption that they are constant with time, after correcting for co-seismic effects, and that the position of the fixed base station (and hence the entire network) may be subject to small errors. Low-order polynomial expressions do not fit the ...

  10. Performance Evaluation of Block Acquisition and Tracking Algorithms Using an Open Source GPS Receiver Platform

    Ramachandran, Ganesh K.; Akopian, David; Heckler, Gregory W.; Winternitz, Luke B.

    2011-01-01

    Location technologies have many applications in wireless communications, military and space missions, etc. US Global Positioning System (GPS) and other existing and emerging Global Navigation Satellite Systems (GNSS) are expected to provide accurate location information to enable such applications. While GNSS systems perform very well in strong signal conditions, their operation in many urban, indoor, and space applications is not robust or even impossible due to weak signals and strong distortions. The search for less costly, faster and more sensitive receivers is still in progress. As the research community addresses more and more complicated phenomena there exists a demand on flexible multimode reference receivers, associated SDKs, and development platforms which may accelerate and facilitate the research. One of such concepts is the software GPS/GNSS receiver (GPS SDR) which permits a facilitated access to algorithmic libraries and a possibility to integrate more advanced algorithms without hardware and essential software updates. The GNU-SDR and GPS-SDR open source receiver platforms are such popular examples. This paper evaluates the performance of recently proposed block-corelator techniques for acquisition and tracking of GPS signals using open source GPS-SDR platform.

  11. GPS receivers timing data processing using neural networks: optimal estimation and errors modeling.

    Mosavi, M R

    2007-10-01

    The Global Positioning System (GPS) is a network of satellites, whose original purpose was to provide accurate navigation, guidance, and time transfer to military users. The past decade has also seen rapid concurrent growth in civilian GPS applications, including farming, mining, surveying, marine, and outdoor recreation. One of the most significant of these civilian applications is commercial aviation. A stand-alone civilian user enjoys an accuracy of 100 meters and 300 nanoseconds, 25 meters and 200 nanoseconds, before and after Selective Availability (SA) was turned off. In some applications, high accuracy is required. In this paper, five Neural Networks (NNs) are proposed for acceptable noise reduction of GPS receivers timing data. The paper uses from an actual data collection for evaluating the performance of the methods. An experimental test setup is designed and implemented for this purpose. The obtained experimental results from a Coarse Acquisition (C/A)-code single-frequency GPS receiver strongly support the potential of methods to give high accurate timing. Quality of the obtained results is very good, so that GPS timing RMS error reduce to less than 120 and 40 nanoseconds, with and without SA. PMID:18098370

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

    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)

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

    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.

  14. Positional accuracy of the Wide Area Augmentation System in consumer-grade GPS units

    Arnold, Lisa L.; Zandbergen, Paul A.

    2011-07-01

    Global Positioning System devices are increasingly being used for data collection in many fields. Consumer-grade GPS units without differential correction have a published horizontal positional accuracy of approximately 10-15 m (average positional accuracy). An attractive option for differential correction for these GPS units is the Wide Area Augmentation System (WAAS). Most consumer-grade GPS units on the market are WAAS capable. According to the Federal Aviation Authority (FAA), the WAAS broadcast message provides integrity information about the GPS signal as well as accuracy improvements, which are reported to improve accuracy to 3-5 m. Limited empirical evidence has been published on the accuracy of WAAS-enabled GPS compared to autonomous GPS. An empirical study was conducted comparing the horizontal and vertical accuracy of WAAS-corrected GPS and autonomous GPS under ideal conditions using consumer-grade receivers. Data were collected for 30-min time spans over accurately surveyed control points. Metrics of median, 68th and 95th percentile, Root Mean Squared Error (RMSE), and average positional accuracy in the horizontal and vertical dimensions were computed and statistically compared. No statistically significant difference was found between WAAS and autonomous position fixes when using two different consumer-grade units. When using WAAS, a third unit type exhibited a statistically significant improvement in positional accuracy. Analysis of data collected for a 27-h time span indicates that while WAAS is altering the estimated position of a point compared to an autonomous position estimate, WAAS augmentation actually appears to decrease the positional accuracy.

  15. Ideas for Future GPS Timing Improvements

    Hutsell, Steven T.

    1996-01-01

    Having recently met stringent criteria for full operational capability (FOC) certification, the Global Positioning System (GPS) now has higher customer expectations than ever before. In order to maintain customer satisfaction, and the meet the even high customer demands of the future, the GPS Master Control Station (MCS) must play a critical role in the process of carefully refining the performance and integrity of the GPS constellation, particularly in the area of timing. This paper will present an operational perspective on several ideas for improving timing in GPS. These ideas include the desire for improving MCS - US Naval Observatory (USNO) data connectivity, an improved GPS-Coordinated Universal Time (UTC) prediction algorithm, a more robust Kalman Filter, and more features in the GPS reference time algorithm (the GPS composite clock), including frequency step resolution, a more explicit use of the basic time scale equation, and dynamic clock weighting. Current MCS software meets the exceptional challenge of managing an extremely complex constellation of 24 navigation satellites. The GPS community will, however, always seek to improve upon this performance and integrity.

  16. Ready To Navigate: Classroom GPS Applications.

    Lucking, Robert A.; Christmann, Edwin P.

    2002-01-01

    Discusses the potential contribution of GPS and related Geographic Information Systems (GIS) technology to education. Provides resources for teachers to plan a lesson on exploring with the help of a GPS device in order to increase students' awareness of their surroundings and broaden understanding of their place in the world. (KHR)

  17. Accurate Finite Difference Algorithms

    Goodrich, John W.

    1996-01-01

    Two families of finite difference algorithms for computational aeroacoustics are presented and compared. All of the algorithms are single step explicit methods, they have the same order of accuracy in both space and time, with examples up to eleventh order, and they have multidimensional extensions. One of the algorithm families has spectral like high resolution. Propagation with high order and high resolution algorithms can produce accurate results after O(10(exp 6)) periods of propagation with eight grid points per wavelength.

  18. GPS-based navigation for space applications

    Champetier, C.; Duhamel, T.; Frezet, M.

    1995-03-01

    We present in this paper a survey of the applications of the GPS (global positioning system) system for spacecraft navigation. The use of the GPS techniques for space missions is a striking example of dual-use of military technology; it can bring vast improvements in performances and, in some cases, for a reduced cost. We only deal in this paper with the functional aspects and performances of GPS uses without addressing the issues of hardware implementation where current developments are leading to an increased miniaturization of the GPS receiver hardware. We start this paper with a general overview of the GPS system and its various uses for space missions. We then focus on four areas where MATRA MARCONI Space has conducted detailed analyses of performances: autonomous navigation for geostationary spacecraft, relative navigation for space rendezvous, differential navigation for landing vehicles, absolute navigation for launchers and reentry vehicles.

  19. GPS Radio Occultation as Part of the Global Observing System for Atmosphere

    Mannucci, Anthony J.; Ao, C. O.; Iijima, B. A.; Wilson, B. D.; Yunck, T. P.; Kursinski, E. R.

    2008-01-01

    Topics include: The Measurement (Physical retrievals based on time standards), GPS Retrieval Products, Retrievals and Radiances: CLARREO Mission, GPS RO and AIRS, GPS RO and Microwave, GPS RO and Radiosondes, GPS/GNSS Science, and Conclusions.

  20. Think GPS offers high security? Think again.

    Johnston, R. G. (Roger G.); Warner, J. S. (Jon S.)

    2004-01-01

    The Global Positioning System (GPS) is being increasingly used for a variety of important applications. These include public safety services (police, fire, rescue, and ambulance), marine and aircraft navigation, vehicle theft monitoring, cargo tracking, and critical time synchronization for utility, telecommunications, banking, and computer industries. Civilian GPS signals-the only ones available to business and to most of the federal government-are high-tech, but not high-security. They were never meant for critical or security applications. Unlike the military GPS signals, civilian GPS satellite signals are unencrypted and unauthenticated. This makes it easy for even relatively unsophisticated adversaries to jam or counterfeit them. Counterfeiting ('spoofing') of civilian GPS signals is particularly troublesome because it is totally surreptitious, and (as we have demonstrated) surprisingly simple. The U.S. Department of Transportation (DOT) has warned of vulnerabilities and looming problems associated with over-reliance and over-confidence in civilian GPS. Few GPS users appear to be paying attention.

  1. Briefing highlights space weather risks to GPS

    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.

  2. Accuracy of velocities from repeated GPS measurements

    Akarsu, V.; Sanli, D. U.; Arslan, E.

    2015-04-01

    Today repeated GPS measurements are still in use, because we cannot always employ GPS permanent stations due to a variety of limitations. One area of study that uses velocities/deformation rates from repeated GPS measurements is the monitoring of crustal motion. This paper discusses the quality of the velocities derived using repeated GPS measurements for the aim of monitoring crustal motion. From a global network of International GNSS Service (IGS) stations, we processed GPS measurements repeated monthly and annually spanning nearly 15 years and estimated GPS velocities for GPS baseline components latitude, longitude and ellipsoidal height. We used web-based GIPSY for the processing. Assuming true deformation rates can only be determined from the solutions of 24 h observation sessions, we evaluated the accuracy of the deformation rates from 8 and 12 h sessions. We used statistical hypothesis testing to assess the velocities derived from short observation sessions. In addition, as an alternative control method we checked the accuracy of GPS solutions from short observation sessions against those of 24 h sessions referring to statistical criteria that measure the accuracy of regression models. Results indicate that the velocities of the vertical component are completely affected when repeated GPS measurements are used. The results also reveal that only about 30% of the 8 h solutions and about 40% of 12 h solutions for the horizontal coordinates are acceptable for velocity estimation. The situation is much worse for the vertical component in which none of the solutions from campaign measurements are acceptable for obtaining reliable deformation rates.

  3. Mining significant semantic locations from GPS data

    Cao, Xin; Cong, Gao; Jensen, Christian S.

    2010-01-01

    With the increasing deployment and use of GPS-enabled devices, massive amounts of GPS data are becoming available. We propose a general framework for the mining of semantically meaningful, significant locations, e.g., shopping malls and restaurants, from such data. We present techniques capable of...... extracting semantic locations from GPS data. We capture the relationships between locations and between locations and users with a graph. Significance is then assigned to locations using random walks over the graph that propagates significance among the locations. In doing so, mutual reinforcement between...

  4. HI Absorption in GPS/CSS Sources

    Pihlström, Y M; Vermeulen, R C

    2002-01-01

    Combining our own observations with data from the literature, we consider the incidence of HI absorption in Gigahertz Peaked Spectrum (GPS) and Compact Steep Spectrum (CSS) sources. Here we present our preliminary results, where we find that the smaller GPS sources (1 kpc). Both a spherical and an axi-symmetric gas distribution, with a radial power law density profile, can be used to explain this anti-correlation between projected linear size and HI column density. Since most detections occur in galaxy classified objects, we argue that if the unified schemes apply to the GPS/CSSs, a disk distribution for the HI is more likely.

  5. GPS meteorology in Africa: highlights from AMMA project

    Bock, O.; Bouin, M.-N.; Doerflinger, E.; Nahmani, S.

    2009-04-01

    A network of six ground-based GPS receivers has been established over West Africa, as part of the instrumental setup of the African Monsoon Multidisciplinary Analysis (AMMA) project. The receivers are located in Djougou (Benin), Niamey (Niger), Gao (Mali), Tamale (Ghana), Ouagadougou (Burkina-Faso), and Tombouctou (Mali). The former three are in operations since June 2005 and the latter since May 2006. Precipitable water vapour (PWV) estimates are retrieved hourly using a geodetic processing of the GPS phase data. Both near-real time (NRT) and post-processed solutions are used depending on the application. The NRT solutions have been useful for verifying numerical weather model predictions mostly during the main observing period (2006) when aircrafts were operated from Niamey and Ouagadougou. The more accurate post-processed solutions have been used for verifying model analyses and have proven extremely useful for detecting and quantifying humidity biases in radiosonde data (some of which were propagated to the model analyses). Radiosonde data represent a major source of information on the upper air variables (humidity, temperature and wind) which are used for process studies (convection during the monsoon season). The seasonal cycle of PWV is very marked and shows a strong correlation with precipitation over West Africa. Analysis of daily GPS PWV estimates reveals five distinct periods within the monsoon season, characterized either by positive or negative tendencies which result from a complex balance between evapotranspiration from the surface, precipitation, and dry and moist air advections in different layers of the atmosphere. Intra-seasonal variability in July to September is observed in precipitation, PWV, and moisture advection at 10-20 day periodicities. The pre-onset period (May-June) is marked by large variability in PW at 3-5 day periodicities, especially at the northern sites. The GPS data provide also unprecedented insight into the diurnal cycle of

  6. Charting pipeline paths : GIS/GPS application zooms into the 21. century

    The Global Positioning System (GPS) was originally developed by the US Defence Department as a navigational tool. Today, portable receivers make it possible for one to determine their precise coordinates on any place on earth in a matter of seconds. GPS technology uses orbiting satellites to pinpoint locations based on the distance and speed of transmission signals. Pipeline professionals use the receivers to locate faults, corrosion damage and cathodic protection flaws. GPS technology is the only accurate alternative to physically measuring pipelines. All the data collected is generally transferred into a geographical information system (GIS) and transposed onto a graphic representation of the pipeline. Details such as coating quality, pipeline composition, surface conditions and landowner status are recorded. Calgary-based Golder Associates Ltd., has developed a computer simulation that incorporates elements extracted from a GIS database. 3 figs

  7. GPS Coordinate Estimates by “a priori” Tropospheric Delays from NWP using Ultra-Rapid Orbits

    R. Santangelo

    2006-06-01

    Full Text Available Comparisons of high accuracy GPS positioning estimates using scientific GPS software through three different processing strategies have been done. The two Italian baselines in a time period of 5 months during 2004 made a calculus data set. For high accuracy GPS differential positioning the employ of global tropospheric delay models can be replaced by the implementation of other techniques. The GPS coordinate repeatability when the tropospheric delay is calculated in near-real time (NRT from a Numerical Weather Prediction (NWP model, is experienced. For the NRT approach IGS Ultra-Rapid orbits instead of Precise orbits were used. Concerning coordinate repeatability, the NWP-based strategy with tropospheric error adjustment appeared as the more accurate (at the submillimetric level with respect to a standard GPS strategy. Furthermore, several hundreds km long baselines demonstrated the standard deviation at the level of millimeters (from 4.2 to 7.6 mm. Practically, the NWP-based strategy offers the advantage of tropospheric delay estimations closer to realistic meteorological values. The application of a more accurate meteorology leads to the satisfactory coordinate estimations, and vice versa the well-defined GPS estimations of coordinates may serve as the additional meteorological parameters source.

  8. Las Necesidades del Trabajador en Salud y el Sistema de Posicionamiento Global (GPS. GPS convencional (GPSC y GPS diferencial (GPSD

    OJ Chang

    1998-01-01

    Full Text Available Los autores explican, desde la perspectiva de las necesidades del trabajador en salud, el uso del GPS, enfatizando la necesidad de utilizar el GPS diferencial cuando se requiere localizar elementos (p. ej. casas, sitios de proliferación de insectos, etc. en el espacio con un alto grado de exactitud, utilizando como ejemplo información correspondiente a un caso real.

  9. A low-cost GPS GSM/GPRS telemetry system: performance in stationary field tests and preliminary data on wild otters (Lutra lutra.

    Lorenzo Quaglietta

    Full Text Available BACKGROUND: Despite the increasing worldwide use of global positioning system (GPS telemetry in wildlife research, it has never been tested on any freshwater diving animal or in the peculiar conditions of the riparian habitat, despite this latter being one of the most important habitat types for many animal taxa. Moreover, in most cases, the GPS devices used have been commercial and expensive, limiting their use in low-budget projects. METHODOLOGY/PRINCIPAL FINDINGS: We have developed a low-cost, easily constructed GPS GSM/GPRS (Global System for Mobile Communications/General Packet Radio Service and examined its performance in stationary tests, by assessing the influence of different habitat types, including the riparian, as well as water submersion and certain climatic and environmental variables on GPS fix-success rate and accuracy. We then tested the GPS on wild diving animals, applying it, for the first time, to an otter species (Lutra lutra. The rate of locations acquired during the stationary tests reached 63.2%, with an average location error of 8.94 m (SD = 8.55. GPS performance in riparian habitats was principally affected by water submersion and secondarily by GPS inclination and position within the riverbed. Temporal and spatial correlations of location estimates accounted for some variation in the data sets. GPS-tagged otters also provided accurate locations and an even higher GPS fix-success rate (68.2%. CONCLUSIONS/SIGNIFICANCE: Our results suggest that GPS telemetry is reliably applicable to riparian and even diving freshwater animals. They also highlight the need, in GPS wildlife studies, for performing site-specific pilot studies on GPS functioning as well as for taking into account eventual spatial and temporal correlation of location estimates. The limited price, small dimensions, and high performance of the device presented here make it a useful and cost-effective tool for studies on otters and other aquatic or

  10. Global Positioning System (GPS) Energetic Particle Data

    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...

  11. Research on GPS Receiver Autonomous Integrity Monitoring Algorithm In the Occurrence of Two-satellite Faults

    Wang Er Shen

    2016-01-01

    Full Text Available Reliability is an essential factor for GPS navigation system. Therefore, an integrity monitoring is considered as one of the most important parts for a navigation system. GPS receiver autonomous integrity monitoring (RAIM technique can detect and isolate fault satellite. Based on particle filter, a novel RAIM method was proposed to detect two-satellite faults of the GPS signal by using hierarchical particle filter. It can deal with any system nonlinear and any noise distributions. Because GNSS measurement noise does not follow the Gaussian distribution perfectly, the particle filter can estimate the posterior distribution more accurately. In order to detect fault, the consistency test statistics is established through cumulative log-likelihood ratio (LLR between the main and auxiliary particle filters (PFs.Specifically, an approach combining PF with the hierarchical filter is used in the process of two-satellite faults. Through GPS real measurement, the performance of the proposed GPS two-satellite faults detection algorithm was illustrated. Some simulation results are given to evaluate integrity monitoring performance of the algorithm. Validated by the real measurement data, the results show that the proposed algorithm can successfully detect and isolate the faulty satellite in the case of non-Gaussian measurement noise.

  12. GPS-leveling using RTK method

    Goleš, Marko

    2007-01-01

    Diploma work focuses on the GPS height determination, using the real-time kinematics surveying method. The work presents an overview of the automated procedure of calculating orthometric heights on the terrain in real-time with support of the mobile computer, the procedure of calculating local geoid surface, all the equations in chronological order from GPS derived WGS84 coordinates to orthometric heights, applying the law of propagation of variances and covariances. Analysis examines obtaine...

  13. GPS and GLONASS Radio Interference in Germany

    Butsch, Felix

    1997-01-01

    The goal of the work described here was to search for interference sources that could pose a threat to the application of GPS for automatic airport approach and landing of aircraft. For this purpose field measurements were conducted in the vicinity of airports, radar facilities andother radio frequency transmitters throughout Germany,and interference resistance measurements of commercial GPS receivers were taken. An additional aim was to examine the interference problems of GLONASS signals. T...

  14. Scintillation Effects on Space Shuttle GPS Data

    Goodman, John L.; Kramer, Leonard

    2001-01-01

    Irregularities in ionospheric electron density result in variation in amplitude and phase of Global Positioning System (GPS) signals, or scintillation. GPS receivers tracking scintillated signals may lose carrier phase or frequency lock in the case of phase sc intillation. Amplitude scintillation can cause "enhancement" or "fading" of GPS signals and result in loss of lock. Scintillation can occur over the equatorial and polar regions and is a function of location, time of day, season, and solar and geomagnetic activity. Mid latitude regions are affected only very rarely, resulting from highly disturbed auroral events. In the spring of 1998, due to increasing concern about scintillation of GPS signals during the upcoming solar maximum, the Space Shuttle Program began to assess the impact of scintillation on Collins Miniaturized Airborne GPS Receiver (MAGR) units that are to replace Tactical Air Control and Navigation (TACAN) units on the Space Shuttle orbiters. The Shuttle Program must determine if scintillation effects pose a threat to safety of flight and mission success or require procedural and flight rule changes. Flight controllers in Mission Control must understand scintillation effects on GPS to properly diagnose "off nominal" GPS receiver performance. GPS data from recent Space Shuttle missions indicate that the signals tracked by the Shuttle MAGR manifest scintillation. Scintillation is observed as anomalous noise in velocity measurements lasting for up to 20 minutes on Shuttle orbit passes and are not accounted for in the error budget of the MAGR accuracy parameters. These events are typically coincident with latitude and local time occurrence of previously identified equatorial spread F within about 20 degrees of the magnetic equator. The geographic and seasonal history of these events from ground-based observations and a simple theoretical model, which have potential for predicting events for operational purposes, are reviewed.

  15. Supply Chain Basics: Tracking Trucks With GPS

    Berney, Gerald

    2008-01-01

    In its most basic form, GPS systems provide a vehicle operator with the vehicle’s position in latitude and longitude. A mapping program is usually integrated, which correlates the vehicle’s position with the location of landmarks. Routing programs (similar to the commonly used Internet driving directions) are generally added to give vehicle operators directions to their destination. The central component of a tracking system is a GPS unit with the ability to locate a container, truck, or rail...

  16. Techniques to improve the GPS precision

    Nelson Acosta

    2012-08-01

    Full Text Available The accuracy of a standard market receiver GPS (Global Positioning System is near 10-15 meters the 95% of the times. To reach a sub-metric level of accuracy some techniques must be used [1]. This article describes some of these procedures to improve the positioning accuracy by using a low-cost GPS in a differential relative positioning way. The proposed techniques are some variations of Kalman, fuzzy logic and information selection.

  17. EGNOS - USE OF GPS SYSTEM FOR APPROACH PROCEDURES

    Ewa Wajszczak; Dominik Galas

    2013-01-01

    Since GPS system became available for common use, a it has been applied in many areas, including aviation. The development of portable GPS receivers provided immeasurable aid in air navigation. The paper presents EGNOS system that ensures the possibility of using GPS system for approach procedure. The article addresses the following issues: the history of creation and development of GPS, principle of system operation, accuracy in relation for GPS system, comparison with conventional radio nav...

  18. Geomagnetic storm effects on GPS based navigation

    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.

  19. Combined constellations GPS and Galileo systems

    Januszewski, Jacek

    As for the users of satellite navigation systems the actual slogan is GPS and Galileo the advantages and disadvantages of different combined constellations of these systems must be taken into account. The distributions (in per cent) of the numbers of satellites visible by the observer at different latitudes situated in open and restricted (urban canyon) area for different masking elevation angles (Hmin) for two combined constellations GPS + Galileo systems (I - 29 GPS satellites + 27 Galileo satellites, II - 29 GPS + 30 Galileo) are presented in this paper. In addition to it the detailed distributions for the observer at latitudes 50-60° for other constellations & elevation angles are demonstrated. For the first constellation the difference between the number of GPS satellites visible by the observer above horizon (Hmin = 0°) at latitudes 50-60° and the number of Galileo satellites visible by the same observer at the same time can be equal each number between plus 7 and minus 7. This fact must be taken into account in the production and the determination of the number of channel of GPS-Galileo integrated receivers.

  20. 4D computerized ionospheric tomography by using GPS measurements and IRI-Plas model

    Tuna, Hakan; Arikan, Feza; Arikan, Orhan

    2016-07-01

    Ionospheric imaging is an important subject in ionospheric studies. GPS based TEC measurements provide very accurate information about the electron density values in the ionosphere. However, since the measurements are generally very sparse and non-uniformly distributed, computation of 3D electron density estimation from measurements alone is an ill-defined problem. Model based 3D electron density estimations provide physically feasible distributions. However, they are not generally compliant with the TEC measurements obtained from GPS receivers. In this study, GPS based TEC measurements and an ionosphere model known as International Reference Ionosphere Extended to Plasmasphere (IRI-Plas) are employed together in order to obtain a physically accurate 3D electron density distribution which is compliant with the real measurements obtained from a GPS satellite - receiver network. Ionospheric parameters input to the IRI-Plas model are perturbed in the region of interest by using parametric perturbation models such that the synthetic TEC measurements calculated from the resultant 3D electron density distribution fit to the real TEC measurements. The problem is considered as an optimization problem where the optimization parameters are the parameters of the parametric perturbation models. Proposed technique is applied over Turkey, on both calm and storm days of the ionosphere. Results show that the proposed technique produces 3D electron density distributions which are compliant with IRI-Plas model, GPS TEC measurements and ionosonde measurements. The effect of the GPS receiver station number on the performance of the proposed technique is investigated. Results showed that 7 GPS receiver stations in a region as large as Turkey is sufficient for both calm and storm days of the ionosphere. Since the ionization levels in the ionosphere are highly correlated in time, the proposed technique is extended to the time domain by applying Kalman based tracking and smoothing

  1. GPS/Galileo navigation in GTO/GEO orbit

    Marmet, François-Xavier; Maureau, Jerome; Calaprice, Massimiliano; Aguttes, Jean Paul

    2015-12-01

    The development of electrically propelled geostationary platforms, together with alternative strategies to reach geostationary orbit, increase the interest for autonomous satellite localization and particularly GNSS navigation for high altitude orbits. It is known that GNSS navigation in GTO/GEO is much more difficult than in LEO since the GNSS receiver is often or permanently at an altitude greater than the altitude of the GNSS constellations, making the GNSS signals drastically less available and weaker. This work is about GPS and Galileo navigation on GEO and GTO orbits, with revised hypotheses compared to studies sometimes more than 15 years old. Moreover, the study goes beyond GNSS geometrical visibility by dealing with operating thresholds and showing the sensitivity to key GNSS receiver thresholds and simulation hypotheses. Comprehensive simulation results and analyses come along with a discussion of the operational benefits of using GPS and Galileo navigation. These data eventually set the ground for a discussion of the key technical options (number and antenna types, GNSS function architecture, signal processing algorithms, orbital filter…). It is shown that using GNSS for GTOGEO orbits is feasible, even considering current spaceborne receivers state-of-the-art, and provides most of the acclaimed benefits of GNSS in LEO, among them more accurate spacecraft localization, precise onboard absolute time and increased autonomy.

  2. Gravity field models derived from Swarm GPS data

    Teixeira da Encarnação, João; Arnold, Daniel; Bezděk, Aleš; Dahle, Christoph; Doornbos, Eelco; van den IJssel, Jose; Jäggi, Adrian; Mayer-Gürr, Torsten; Sebera, Josef; Visser, Pieter; Zehentner, Norbert

    2016-07-01

    It is of great interest to numerous geophysical studies that the time series of global gravity field models derived from Gravity Recovery and Climate Experiment (GRACE) data remains uninterrupted after the end of this mission. With this in mind, some institutes have been spending efforts to estimate gravity field models from alternative sources of gravimetric data. This study focuses on the gravity field solutions estimated from Swarm global positioning system (GPS) data, produced by the Astronomical Institute of the University of Bern, the Astronomical Institute (ASU, Czech Academy of Sciences) and Institute of Geodesy (IfG, Graz University of Technology). The three sets of solutions are based on different approaches, namely the celestial mechanics approach, the acceleration approach and the short-arc approach, respectively. We derive the maximum spatial resolution of the time-varying gravity signal in the Swarm gravity field models to be degree 12, in comparison with the more accurate models obtained from K-band ranging data of GRACE. We demonstrate that the combination of the GPS-driven models produced with the three different approaches improves the accuracy in all analysed monthly solutions, with respect to any of them. In other words, the combined gravity field model consistently benefits from the individual strengths of each separate solution. The improved accuracy of the combined model is expected to bring benefits to the geophysical studies during the period when no dedicated gravimetric mission is operational.

  3. Building a GPS Receiver for Space Lessons Learned

    Sirotzky, Steve; Heckler, G. W.; Boegner, G.; Roman, J.; Wennersten, M.; Butler, R.; Davis, M.; Lanham, A.; Winternitz, L.; Thompson, W.; Bamford, B.; Banes, V.

    2008-01-01

    Over the past 4 years the Component Systems and Hardware branch at NASA GSFC has pursued an inhouse effort to build a unique space-flight GPS receiver. This effort has resulted in the Navigator GPS receiver. Navigator's first flight opportunity will come with the STS-125 HST-SM4 mission in August 2008. This paper covers the overall hardware design for the receiver and the difficulties encountered during the transition from the breadboard design to the final flight hardware design. Among the different lessons learned, the paper stresses the importance of selecting and verifying parts that are appropriate for space applications, as well as what happens when these parts are not accurately characterized by their datasheets. Additionally, the paper discusses what analysis needs to be performed when deciding system frequencies and filters. The presentation also covers how to prepare for thermal vacuum testing, and problems that may arise during vibration testing. It also contains what criteria should be considered when determining which portions of a design to create in-house, and which portions to license from a third party. Finally, the paper shows techniques which have proven to be extraordinarily helpful in debugging and analysis.

  4. Precise orbit determination based on raw GPS measurements

    Zehentner, Norbert; Mayer-Gürr, Torsten

    2016-03-01

    Precise orbit determination is an essential part of the most scientific satellite missions. Highly accurate knowledge of the satellite position is used to geolocate measurements of the onboard sensors. For applications in the field of gravity field research, the position itself can be used as observation. In this context, kinematic orbits of low earth orbiters (LEO) are widely used, because they do not include a priori information about the gravity field. The limiting factor for the achievable accuracy of the gravity field through LEO positions is the orbit accuracy. We make use of raw global positioning system (GPS) observations to estimate the kinematic satellite positions. The method is based on the principles of precise point positioning. Systematic influences are reduced by modeling and correcting for all known error sources. Remaining effects such as the ionospheric influence on the signal propagation are either unknown or not known to a sufficient level of accuracy. These effects are modeled as unknown parameters in the estimation process. The redundancy in the adjustment is reduced; however, an improvement in orbit accuracy leads to a better gravity field estimation. This paper describes our orbit determination approach and its mathematical background. Some examples of real data applications highlight the feasibility of the orbit determination method based on raw GPS measurements. Its suitability for gravity field estimation is presented in a second step.

  5. Integration of InSAR and GPS for hydraulic engineering

    HE; XiuFeng; LUO; HaiBin; HUANG; QiHuan; HE; Min

    2007-01-01

    Interferometric synthetic aperture radar (InSAR) is a potential earth observation approach,and it has been demonstrated to have a variety of applications in measuring ground movement,urban subsidence and landslides.Currently InSAR provides the ability to map accurate DEM and measure ground deformation to sub-centimeter accuracy.However,many factors affect InSAR to measure ground movement since dam constructions are built in a large scale area with a complicated climate and unstable geology.This paper discusses potential applications of integrated InSAR and GPS to monitor a large-scale ground movement due to hydropower developments.The integration of InSAR and GPS can provide a cost-effective means for monitoring deformation of hydropower developments.Moreover,two novel methods,both the improved spatial interpolating method and estimation of 3D surface motion velocities method,are proposed and the experimental results and analysis are given in this paper.

  6. GPS Remote Sensing Measurements Using Aerosonde UAV

    Grant, Michael S.; Katzberg, Stephen J.; Lawrence, R. W.

    2005-01-01

    In February 2004, a NASA-Langley GPS Remote Sensor (GPSRS) unit was flown on an Aerosonde unmanned aerial vehicle (UAV) from the Wallops Flight Facility (WFF) in Virginia. Using direct and surface-reflected 1.575 GHz coarse acquisition (C/A) coded GPS signals, remote sensing measurements were obtained over land and portions of open water. The strength of the surface-reflected GPS signal is proportional to the amount of moisture in the surface, and is also influenced by surface roughness. Amplitude and other characteristics of the reflected signal allow an estimate of wind speed over open water. In this paper we provide a synopsis of the instrument accommodation requirements, installation procedures, and preliminary results from what is likely the first-ever flight of a GPS remote sensing instrument on a UAV. The correct operation of the GPSRS unit on this flight indicates that Aerosonde-like UAV's can serve as platforms for future GPS remote sensing science missions.

  7. Ionospheric irregularities at Antarctic using GPS measurements

    Sunita Tiwari; Amit Jain; Shivalika Sarkar; Sudhir Jain; A K Gwal

    2012-04-01

    The purpose of this work is to study the behaviour of the ionospheric scintillation at high latitude during geomagnetically quiet and disturbed conditions which is one of the most relevant themes in the space weather studies. Scintillation is a major problem in navigation application using GPS and in satellite communication at high latitudes. Severe amplitude fading and strong scintillation affect the reliability of GPS navigational system and satellite communication. To study the effects of the ionospheric scintillations, GPS receiver installed at Antarctic station Maitri (Geog. 70.76°S; 11.74°E) was used. The data is collected by using GISTM 4004A, NOVATEL’S GPS receiver during March 2008. Studies show that percentage occurrence of phase scintillation is well correlated with geomagnetic activity during the observation period. The result also shows that very intense scintillations can degrade GPS based location determination due to loss of lock of satellites. These findings indicate that the dependence of scintillations and irregularity occurrence on geomagnetic activity is associated with the magnetic local time (MLT). Large number of patches are reported and their activity depends on the magnetic activity index.

  8. SITE-SPECIFIC DECISION-MAKING BASED ON RTK GPS SURVEY AND SIX ALTERNATIVE ELEVATION DATA SOURCES: SOIL EROSION PREDICTION

    Soil erosion modeling requires substantial and accurate data to obtain meaningful results for decision-making in soil and water conservation practices. Today's precision farming equipment based on Global Positioning Systems (GPS), enables landowners to gather spatially distributed topographic data i...

  9. GPS as a solar observational instrument: real-time estimation of EUV photons flux rate during strong, medium, and weak solar flares

    Singh, Talwinder; Hernández Pajares, Manuel; Monte Moreno, Enrique; García Rigo, Alberto; Olivares Pulido, German

    2015-01-01

    In this manuscript, the authors show how the Global Navigation Satellite Systems, GNSS (exemplified in the Global Positioning System, GPS), can be efficiently used for a very different purpose from that for which it was designed as an accurate Solar observational tool, already operational from the open global GPS measurements available in real-time, and with some advantages regarding dedicated instruments onboard spacecraft. The very high correlation of the solar extreme ultraviolet (EUV) pho...

  10. Quarry monitoring using GPS measurements and UAV photogrammetry

    Nikolakopoulos, Konstantinos G.; Koukouvelas, Ioannis; Argyropoulos, NIkolaos; Megalooikonomou, Vasileios

    2015-10-01

    The objective of this work is to indicate a monitoring methodology in order to survey the present state of the quarry sites and their evolution in time, which are the basic data needed to implement an adequate land reclamation project. The land monitoring has been realised by UAV photogrammetry and GPS measurements supported by a Geographic Information System. A six-rotor aircraft with a total weight of 6 kg carrying two small cameras has been used. Very accurate digital airphotos have been used in order to create orthophotos mosaic and DSM from the quarry planes. DGPS measurements and the data captured from the UAV are combined in GIS and the results are presented in the current study.

  11. Lightweight GPS-tags, one giant leap for wildlife tracking? An assessment approach.

    Mariano R Recio

    Full Text Available Recent technological improvements have made possible the development of lightweight GPS-tagging devices suitable to track medium-to-small sized animals. However, current inferences concerning GPS performance are based on heavier designs, suitable only for large mammals. Lightweight GPS-units are deployed close to the ground, on species selecting micro-topographical features and with different behavioural patterns in comparison to larger mammal species. We assessed the effects of vegetation, topography, motion, and behaviour on the fix success rate for lightweight GPS-collar across a range of natural environments, and at the scale of perception of feral cats (Felis catus. Units deployed at 20 cm above the ground in sites of varied vegetation and topography showed that trees (native forest and shrub cover had the largest influence on fix success rate (89% on average; whereas tree cover, sky availability, number of satellites and horizontal dilution of position (HDOP were the main variables affecting location error (±39.5 m and ±27.6 m before and after filtering outlier fixes. Tests on HDOP or number of satellites-based screening methods to remove inaccurate locations achieved only a small reduction of error and discarded many accurate locations. Mobility tests were used to simulate cats' motion, revealing a slightly lower performance as compared to the fixed sites. GPS-collars deployed on 43 cats showed no difference in fix success rate by sex or season. Overall, fix success rate and location error values were within the range of previous tests carried out with collars designed for larger species. Lightweight GPS-tags are a suitable method to track medium to small size species, hence increasing the range of opportunities for spatial ecology research. However, the effects of vegetation, topography and behaviour on location error and fix success rate need to be evaluated prior to deployment, for the particular study species and their habitats.

  12. The SMS-GPS-Trip-Method

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

    2015-01-01

    data, an approach which is not well suited for capturing data on experiences surrounding trips. Currently increasing research is being done on how to incorporate such data in traffic models, and there is therefore a need for a method, which is suited to collect such data. The new method presented in......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...... this article builds on ideas from experience sampling methods (ESM) and it is well suited specifically for collecting such experience data. Given the use of SMS technology, this method makes it possible to reach a wide range of respondents. The usefulness of the new method is proven on a theoretical...

  13. An Autonomous Vehicle for Farming Using GPS

    Neelam Rup Prakash

    2012-06-01

    Full Text Available This paper presents the automatic steering control of farming vehicle using GPS receiver. Automatic steering devices for farming vehicles like tractors, seeding vehicle, weed control vehicle, spraying machine vehicle etc. have the task to relieve the driver from the physical and mental stress of monotonous steering work. Simultaneously, they are intended to help him to exploit machines and farming vehicle closer to their full performance and improve the quality of work. Vehicles frequently have to be steered in and exact straight line and along rows in the farm land.GPS receiver fetches the information of positions (latitude and longitude of the farm land which needs to be cultivated. With the help of GPS and microcontroller (Arm9 we calculate the boundary of farm land, slope of straight line and angle of movement with the help of slope changes. The microcontroller generates the control signals to stepper motor for steering of vehicle.

  14. GPS-SNO: computational prediction of protein S-nitrosylation sites with a modified GPS algorithm.

    Yu Xue

    Full Text Available As one of the most important and ubiquitous post-translational modifications (PTMs of proteins, S-nitrosylation plays important roles in a variety of biological processes, including the regulation of cellular dynamics and plasticity. Identification of S-nitrosylated substrates with their exact sites is crucial for understanding the molecular mechanisms of S-nitrosylation. In contrast with labor-intensive and time-consuming experimental approaches, prediction of S-nitrosylation sites using computational methods could provide convenience and increased speed. In this work, we developed a novel software of GPS-SNO 1.0 for the prediction of S-nitrosylation sites. We greatly improved our previously developed algorithm and released the GPS 3.0 algorithm for GPS-SNO. By comparison, the prediction performance of GPS 3.0 algorithm was better than other methods, with an accuracy of 75.80%, a sensitivity of 53.57% and a specificity of 80.14%. As an application of GPS-SNO 1.0, we predicted putative S-nitrosylation sites for hundreds of potentially S-nitrosylated substrates for which the exact S-nitrosylation sites had not been experimentally determined. In this regard, GPS-SNO 1.0 should prove to be a useful tool for experimentalists. The online service and local packages of GPS-SNO were implemented in JAVA and are freely available at: http://sno.biocuckoo.org/.

  15. Single-Receiver GPS Phase Bias Resolution

    Bertiger, William I.; Haines, Bruce J.; Weiss, Jan P.; Harvey, Nathaniel E.

    2010-01-01

    Existing software has been modified to yield the benefits of integer fixed double-differenced GPS-phased ambiguities when processing data from a single GPS receiver with no access to any other GPS receiver data. When the double-differenced combination of phase biases can be fixed reliably, a significant improvement in solution accuracy is obtained. This innovation uses a large global set of GPS receivers (40 to 80 receivers) to solve for the GPS satellite orbits and clocks (along with any other parameters). In this process, integer ambiguities are fixed and information on the ambiguity constraints is saved. For each GPS transmitter/receiver pair, the process saves the arc start and stop times, the wide-lane average value for the arc, the standard deviation of the wide lane, and the dual-frequency phase bias after bias fixing for the arc. The second step of the process uses the orbit and clock information, the bias information from the global solution, and only data from the single receiver to resolve double-differenced phase combinations. It is called "resolved" instead of "fixed" because constraints are introduced into the problem with a finite data weight to better account for possible errors. A receiver in orbit has much shorter continuous passes of data than a receiver fixed to the Earth. The method has parameters to account for this. In particular, differences in drifting wide-lane values must be handled differently. The first step of the process is automated, using two JPL software sets, Longarc and Gipsy-Oasis. The resulting orbit/clock and bias information files are posted on anonymous ftp for use by any licensed Gipsy-Oasis user. The second step is implemented in the Gipsy-Oasis executable, gd2p.pl, which automates the entire process, including fetching the information from anonymous ftp

  16. A GPS Receiver for Lunar Missions

    Bamford, William A.; Heckler, Gregory W.; Holt, Greg N.; Moreau, Michael C.

    2008-01-01

    Beginning with the launch of the Lunar Reconnaissance Orbiter (LRO) in October of 2008, NASA will once again begin its quest to land humans on the Moon. This effort will require the development of new spacecraft which will safely transport people from the Earth to the Moon and back again, as well as robotic probes tagged with science, re-supply, and communication duties. In addition to the next-generation spacecraft currently under construction, including the Orion capsule, NASA is also investigating and developing cutting edge navigation sensors which will allow for autonomous state estimation in low Earth orbit (LEO) and cislunar space. Such instruments could provide an extra layer of redundancy in avionics systems and reduce the reliance on support and on the Deep Space Network (DSN). One such sensor is the weak-signal Global Positioning System (GPS) receiver "Navigator" being developed at NASA's Goddard Space Flight Center (GSFC). At the heart of the Navigator is a Field Programmable Gate Array (FPGA) based acquisition engine. This engine allows for the rapid acquisition/reacquisition of strong GPS signals, enabling the receiver to quickly recover from outages due to blocked satellites or atmospheric entry. Additionally, the acquisition algorithm provides significantly lower sensitivities than a conventional space-based GPS receiver, permitting it to acquire satellites well above the GPS constellation. This paper assesses the performance of the Navigator receiver based upon three of the major flight regimes of a manned lunar mission: Earth ascent, cislunar navigation, and entry. Representative trajectories for each of these segments were provided by NASA. The Navigator receiver was connected to a Spirent GPS signal generator, to allow for the collection of real-time, hardware-in-the-loop results for each phase of the flight. For each of the flight segments, the Navigator was tested on its ability to acquire and track GPS satellites under the dynamical

  17. Combining GPS measurements and IRI model predictions

    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

  18. Fast error analysis of continuous GPS observations

    Bos, M.S.; Fernandes, R. M. S.; Williams, S. D. P.; Bastos, L.

    2007-01-01

    It has been generally accepted that the noise in continuous GPS observations can be well described by a power-law plus white noise model. Using maximum likelihood estimation (MLE) the numerical values of the noise model can be estimated. Current methods require calculating the data covariance matrix and inverting it, which is a significant computational burden. Analysing 10 years of daily GPS solutions of a single station can take around 2 h on a regular computer such as a PC with an AMD Athl...

  19. Applying GPS to check horizontal control quality

    Jakub Vincent; Weiss Gabriel; Sabová Jana

    2004-01-01

    GPS technologies can also be used for check quality in available horizontal point set with coordinates CJ of the frame S-JTSK. When survey and setting-out tasks should be performed in certain area, one can found in it allways some points of the fundamental and detail state controls. To use these points for some actual aims, it is necessary to investigate their compatibility (among the point mark positions and the point coordinate of control points). This can be done using GPS surveying that m...

  20. Limmex GPS -kello tuotteena ja palveluna

    Nuutinen, Antti

    2015-01-01

    Insinöörityössä perehdyttiin Limmex GPS -paikantavaan turvakelloon sekä luotiin malli laitteen ympärille muodostettavasta palvelusta. Tavoitteena oli selvittää, miten hyvin laite soveltuu asiakaskäyttöön erilaisille käyttäjille sekä esittää ehdotus laitteen sekä koko turvapalvelun tuotteistamiseksi sekä palvelun muotoiluun. Työn tarkoituksena oli edistää työn tilaajana toimivan Turvallinen Koti Oy:n suunnitelmaa tuoda Limmex GPS -kello markkinoille osana tuote-/ palveluvalikoimaansa. Työs...

  1. GPS landy system (GPS land dynamic management system). Jinko eisei GPS ni yoru doko sogo kanri system

    Kanzaki, T.; Nishizawa, S. (Taisei Corp., Tokyo (Japan))

    1991-09-15

    A GPS LANDY system was developed, which is characterized in overall systematization of large scale land constructions, intended to improve its efficiency, by means of linking the shape measurement utilizing satellites with various types of land management. The GPS is an observation system using 18 satellites, three each on six orbits, orbifing in an altitude of 20,000 km. Because of the conventional GPS requiring three hours, and in addition, having as poor accuracy as several ten meters, a GPS dynamic position measuring method was developed, which is applied with such an improvement as installing receiving antennas at the measuring points. As a result, recording the three-dimensional coordinates has become possible instantaneously and continuously; the system can be operated by a single operator; simultaneous multi-point measurements have become possible if the number of receivers is increased; quick and wide-area three-dimensional topographic measurement has become possible; and the accuracy was improved to 1 cm. Utilization of these measurement data to various construction management systems led to a completion of the overall land management system. 5 figs.

  2. Mitigate Effects of Multipath Interference at GPS Using Separate Antennas

    Younis H. Karim AlJewari

    2014-07-01

    Full Text Available Multipath is one of the contributing sources of errors that effect on the accuracy and reliability of the Global Positioning System (GPS. GPS multipath is caused by the reception of signals from satellites directly and indirectly reflected from the local objects. This paper investigates multipath errors at the GPS receiver antenna and the possibility to mitigate multipath interference effect by use two separate antennas model GA 25 MCX with one GPS receiver card (GARMIN GPS 25LP Series are GPS sensor boards designed for a broad spectrum of OEM (Original Equipment Manufacturer to improve accuracy and reliability of GPS. We used a specially designed simulator platform to simulate the movement and the reflection of GPS signals from the body of platform.

  3. A New GPS System for Continuous Deformation Monitoring

    2000-01-01

    This paper presents a multi-antenna GPS based system developed for localcontinuous deformation monitoring. Due to a large number of points that needs to be monitored,the standard approaches of using permanent GPS receiver arrays will cause high cost. Iteventually becomes the limiting factor for large-scale use of GPS in these application areas.Multi-antenna GPS system allows a number of GPS antennas to be linked to one GPS receiverby a specially designed electronic component, i.e. the so-called GPS multi-antenna switch(GMS), The receiver takes data sequentially from each of the antennas attached to thereceiver. A distinctive advantage of the approach is that one GPS receiver can be used tomonitor more than one point. The cost per monitored point (i. e. the expenses of hardware)istherefore significantly reduced.

  4. Reprocessed height time series of GPS stations at tide gauges

    S. Rudenko; Schön, N.; Uhlemann, M; G. Gendt

    2012-01-01

    Precise weekly positions of 403 Global Positioning System (GPS) stations located worldwide are obtained by reprocessing GPS data of these stations at the time span from 4 January 1998 until 29 December 2007. The used processing algorithm and models as well as the solution and results obtained are presented. Vertical velocities of GPS stations having tracking history longer than 2.5 yr are computed and compared with the estimates from the colocated tide gauges and other GPS solutions. Examples...

  5. Accuracy Analysis of GPS Positioning Near the Forest Environment

    Atinç Pirti

    2008-01-01

    GPS has become an essential tool for georeferencing. In some cases, GPS is used for unfavorable conditions although it was developed for open field studies. This paper analyzes the achievable accuracy and performance of GPS near the forest. Three surveying marks have been established with the distance seperation fivemeter in length. Two GPS campaigns were conducted for the selected marks in the forest. The same campaign was repeated once again after the forest was cut off. The experiments dem...

  6. Fine tuning GPS clock estimation in the MCS

    Hutsell, Steven T.

    1995-01-01

    With the completion of a 24 operational satellite constellation, GPS is fast approaching the critical milestone, Full Operational Capability (FOC). Although GPS is well capable of providing the timing accuracy and stability figures required by system specifications, the GPS community will continue to strive for further improvements in performance. The GPS Master Control Station (MCS) recently demonstrated that timing improvements are always composite Clock, and hence, Kalman Filter state estimation, providing a small improvement to user accuracy.

  7. A HYBRID APPROACH TO GPS IMPROVEMENT IN URBAN CANYONS

    Ashwani Kumar Aggarwal *

    2015-01-01

    GPS has become important tool in everyday life for safe and convenient transportation of automobiles. Pedestrians use hand held smart devices to know their own position in a town, modern vehicles in intelligent transport systems use relatively sophisticated GPS receivers for estimating current position of vehicle for safe driving. However, in urban areas with canyon of buildings where the GPS satellites are occluded by tall buildings, trees and reflections of GPS signals from near...

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

    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

  9. Accuracy assessment of GPS and surveying technique in forest road mapping

    Ehsan Abdi

    2012-12-01

    Full Text Available Forest road networks provide access to the forest as a source of timber production and tourism services. Moreover, it is considered the main tool to protect forests from fire and smuggling. The prerequisite of road management and maintenance planning is to have spatial distribution and map of the roads. But newly constructed or some other forest road segments are not available in national maps. Therefore, mapping these networks is raised as a priority for a forest manager. The aim of this study was to assess accuracy of routine methods in road mapping. For this purpose, Patom district forest road was selected and road network map was extracted from the National Cartographic Center maps as the ground truth or base map. The map of the network was acquired using two methods, a GPS receiver and survey technique. Selecting 70 sample points on the network and considering the National Cartographic Center map as base map, accuracy was determined for two methods. The results showed that while the survey method was more accurate at the beginning of the path (first 500 meters, accumulation of errors resulted in higher rates of error in this method (up to 263 meters compared to GPS. Mann-Whitney test revealed significant differences in accuracy of two methods and mean accuracies were 38.86 and 147.90 for GPS and surveying respectively. The results showed that for samples 1-15 there was no significant difference between the survey and GPS data but for samples 28-42 and 56-70 statistically significant difference were existed between the survey and GPS data. Regression analysis showed that the relation between GPS and surveying accuracies and distance were best defined by cubic (R2 adj = 0.65 and linear (R2 adj = 0.83 regression models respectively. Applying 10 and 5 meters buffers around base map, 68 and 41% of GPS and 44 and 21% of surveying derived road were overlapped with buffer zones. The time required to complete the survey was found to increase the

  10. Accuracy assessment of GPS and surveying technique in forest road mapping

    Ehsan Abdi

    2012-11-01

    Full Text Available Forest road networks provide access to the forest as a source oftimber production and tourism services. Moreover, it is considered the main tool to protect forests from fire and smuggling. The prerequisite of road management and maintenance planning is to have spatial distribution and map of the roads. But newly constructed or some other forest road segments are not available in national maps. Therefore, mapping these networks is raised as a priority for a forest manager. The aim of this study was to assess accuracy of routine methods in road mapping. For this purpose, Patom district forest road was selected and road network map was extracted from the NationalCartographic Center maps as the ground truth or base map. The map of the network was acquired using two methods, a GPS receiver and survey technique.Selecting 70 sample points on the network and considering the NationalCartographic Center map as base map, accuracy was determined fortwo methods. The results showed that while the survey method was more accurate at the beginning of the path (first 500 meters, accumulation of errors resulted in higher rates of error in this method (up to 263 meters compared to GPS. Mann-Whitney test revealed significant differences in accuracy of two methods and mean accuracies were 38.86 and 147.90 for GPS and surveying respectively. The results showed that for samples 1-15 there was no significant difference between the survey and GPS data but for samples 28-42 and 56-70 statistically significant difference were existed between the survey and GPS data. Regression analysis showed that the relation between GPS and surveying accuracies and distance were best defined by cubic (R2adj= 0.65 and linear (R2 adj = 0.83 regression models respectively. Applying 10 and 5 meters buffers around base map, 68 and 41% of GPS and 44 and 21% of surveying derived road were overlapped with buffer zones. The time required to complete the survey was found to increase the overall

  11. Investigating Atmospheric Rivers using GPS TPW during CalWater 2015

    Almanza, V.; Foster, J. H.; Businger, S.

    2015-12-01

    Ship-based Global Positioning System (GPS) receivers have been successful in obtaining millimeter accuracy total precipitable water (TPW). We apply this technique with a field experiment using a GPS meteorology system installed on board the R/V Ronald Brown during the CalWater 2015 project. The goal of CalWater is to monitor atmospheric river (AR) events over the Eastern Pacific Ocean and improve forecasting of the extreme precipitation events they can produce. During the 30-day cruise, TPW derived from radiosonde balloons released from the Ron Brown are used to verify the accuracy of shipboard GPS TPW. The results suggest that ship-based GPS TPW offers a cost-effective approach for acquiring accurate real-time meteorological observations of TPW in AR's over remote oceans, as well as near the coastlines where satellites algorithms have limited accuracy. The results have implications for augmenting operational observing networks to improve weather prediction and nowcasting of ARs, thereby supporting hazard response and mitigation efforts associated with coastal flooding events.

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

    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.

  13. 78 FR 63459 - GPS Satellite Simulator Control Working Group Meeting

    2013-10-24

    ... Force GPS Satellite Simulator Control Working Group Meeting AGENCY: Department of the Air Force. ACTION: Meeting Notice. SUMMARY: This meeting notice is to inform GPS simulator manufacturers, who supply products to the Department of Defense (DoD), and GPS simulator users, both government and DoD...

  14. 78 FR 67132 - GPS Satellite Simulator Control Working Group Meeting

    2013-11-08

    ... Department of the Air Force GPS Satellite Simulator Control Working Group Meeting AGENCY: Space and Missile Systems Center, Global Positioning Systems (GPS) Directorate, Air Force, DoD. ACTION: Meeting notice..., 2013 Vol. 78 No. 206. This new meeting notice is to inform GPS simulator manufacturers, who...

  15. 77 FR 70421 - GPS Satellite Simulator Control Working Group Meeting

    2012-11-26

    ... 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 simulator manufacturers, who supply...

  16. Comparison of the precision of three commonly used GPS models

    E Chavoshi

    2016-04-01

    farming operations as well as the efficiency of the work done in different situations. Materials and Methods: In this study, three commonly used GPS models belong to GARMIN CO. were selected for comparison. This company is the world biggest manufacturer of GPS device. Three models include eTrex VISTA, MAP 60 csx and MAP 78s that in recent years have been the most widely used receivers in precision agriculture (Figure 1, Table 1. To assess the accuracy and precision of the receivers, 9 recording stations were selected in a field (20×20 m2 and detailed mapping by the odolite camera under high precision compass networks and regular conditions (figure 2 was identified. To reduce the error of multi-path, a relatively open and unobstructed place in the Abbas Abad field of Bu-Ali Sina University were considered. This study was conducted in a Completely Randomized Design (CRD with factorial analysis to examine three factors, at three levels, each in three replication including weather conditions (clear, partially cloudy and full cloudy sky, time of day (9 am, 12 am and 4 pm and three different models of receiver (MAP 60 csx, eTrex VISTA and MAP 78s, in 9 local stations. Difference of deviation value at each station with the mean value of latitude and longitude recorded at same station was used to precision calculate on (equation 1 and the difference of deviation value at each station with a deviation of the actual position latitude and longitude of the same station was used to calculate the accuracy (equation 2. The base station position (No.1 was determined with an accurately large-scale map. Then, the positions of other stations were defined with camera and compass in exact rectangular grid by underlying base station. Mean error for each station using equation (3 and the precision and accuracy and the definitions of each receiver was calculated. Results and Discussion: To display the geographical distribution stations and the registered location data for GPS devices Arc

  17. Convective towers detection using GPS radio occultations

    Biondi, Riccardo; Neubert, Torsten; Syndergaard, S.;

    an important role since they lead to deep convective activity. With this work we want to investigate if severe storms leave a significant signature in radio occultation profiles in the tropical tropopause layer. The GPS radio occultation (RO) technique is useful for studying severe weather phenomena because...

  18. En Billig GPS Data Analyse Platform

    Andersen, Ove; Christiansen, Nick; Larsen, Niels T.; Torp, Kristian

    2011-01-01

    Denne artikel præsenterer en komplet software platform til analyse af GPS data. Platformen er bygget udelukkende vha. open-source komponenter. De enkelte komponenter i platformen beskrives i detaljer. Fordele og ulemper ved at bruge open-source diskuteres herunder hvilke IT politiske tiltage, der...

  19. Integrating GPS with Dead Reckoning Sensors

    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...

  20. Processing GPS Occultation Data To Characterize Atmosphere

    Hajj, George; Kursinski, Emil; Leroy, Stephen; Lijima, Byron; de la Torre Juarez, Manuel; Romans, Larry; Ao, Chi

    2005-01-01

    GOAS [Global Positioning System (GPS) Occultation Analysis System] is a computer program that accepts signal-occultation data from GPS receivers aboard low-Earth-orbiting satellites and processes the data to characterize the terrestrial atmosphere and, in somewhat less comprehensive fashion, the ionosphere. GOAS is very robust and can be run in an unattended semi-operational processing mode. It features sophisticated retrieval algorithms that utilize the amplitudes and phases of the GPS signals. It incorporates a module that, using an assumed atmospheric refractivity profile, simulates the effects of the retrieval processing system, including the GPS receiver. GOAS utilizes the GIPSY software for precise determination of orbits as needed for calibration. The GOAS output for the Earth s troposphere and mid-to-lower stratosphere consists of high-resolution (<1 km) profiles of density, temperature, pressure, atmospheric refractivity, bending angles of signals, and water-vapor content versus altitude from the Earth s surface to an altitude of 30 km. The GOAS output for the ionosphere consists of electron-density profiles from an altitude of about 50 km to the altitude of a satellite, plus parameters related to the rapidly varying structure of the electron density, particularly in the E layer of the ionosphere.

  1. The covariance of GPS coordinates and frames

    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

  2. GPS LifePlan--Leading Campus Change

    Litecky, Larry; Bruner, Mike; Hageman, Kristin

    2009-01-01

    The Goals + Plans = Success (GPS) LifePlan is a new and innovative approach to assist and support students in answering critical questions that give direction to their pursuit of success. The program has brought impressive cultural changes to Century College. It benefited new students by establishing a framework for critical decision making that…

  3. Development of a GPS Seamless Archive

    Scharber, M.; Bock, Y.; Gilmore, B.

    2003-12-01

    The Scripps Orbit and Permanent Array Center (SOPAC) has completed development of software for UNAVCO's GPS Seamless Archive Center (GSAC). The GSAC is a collection of GPS data archives and their operating agencies that have agreed to exchange information about their individual data holdings. GSAC allows a user to locate GPS data and metadata from these different archives through a single interface; hence GSAC is an operating virtual observatory for continuous and "campaign" GPS data. Data providers collect or generate data and then supply the data to data wholesalers. Data wholesalers collect and archive data and metadata, from one or more data providers. GSAC currently has 7 U.S.-based data wholesalers (NASA's CDDIS, UC Berkeley's NCEDC, NGS, CWU's PANGA archive, SCEC, SOPAC, and UNAVCO). Together these archives hold over 2 million GPS data (RINEX) files collected for over 10,000 monuments, including a nearly complete set of data collected between 1986 and 2003 for the global network and western North America, and a significant quantity of data collected by U.S. scientists in other tectonically active regions. Data retailers collect information from the wholesalers in a well-defined manner and run a service for clients to access the information. Currently there are two GSAC retailers (SOPAC and UNAVCO). The GSAC software suite includes a Web-based interactive client (GSAC Wizard) to locate data, a command-line client to locate and download data, and a retailer service that uses a macro language to pass commands to a server using the http url. The command-line client uses the retailer service to communicate with the retailer server. SOPAC has also modified its map interface to work with GSAC so that GPS data can be located using a spatial context, and maintains a GSAC Home Page (http://gsac.ucsd.edu). In this abstract, we highlight achievements and lessons learned from our development of the current system, but focus on a possible next generation GSAC that will

  4. Do French Low-Income GPs Choose to Work Less ?

    2011-01-01

    In France, a significant number of General Practitioners (GPs) earn less than 1.5 times the French minimum salary. Using a representative panel of self-employed GPs over the years 1993-2004, this paper tests whether these low-income GPs choose to work less than all other GPs or whether they are constrained to do so. The test is based on measuring reactions to positive and negative demand shocks. As low-income GPs do not increase activity in response to a positive demand shock but decrease act...

  5. EGNOS - USE OF GPS SYSTEM FOR APPROACH PROCEDURES

    Ewa Wajszczak

    2013-03-01

    Full Text Available Since GPS system became available for common use, a it has been applied in many areas, including aviation. The development of portable GPS receivers provided immeasurable aid in air navigation. The paper presents EGNOS system that ensures the possibility of using GPS system for approach procedure. The article addresses the following issues: the history of creation and development of GPS, principle of system operation, accuracy in relation for GPS system, comparison with conventional radio navigation ILS system and potential benefits from implementing EGNOS.

  6. GPs' Perceptions of Cardiovascular Risk and Views on Patient Compliance

    Barfoed, Benedicte Marie Lind; Jarbøl, Dorte Ejg; Paulsen, Maja Skov; Christensen, Palle Mark; Halvorsen, Peder Andreas; Nielsen, Jesper Bo; Søndergaard, Jens

    2015-01-01

    Objective. General practitioners' (GPs') perception of risk is a cornerstone of preventive care. The aims of this interview study were to explore GPs' professional and personal attitudes and experiences regarding treatment with lipid-lowering drugs and their views on patient compliance. Methods...... for managing patient compliance, and (3) GPs' own risk management. There were substantial differences in the attitudes concerning all three themes. Conclusions. The substantial differences in the GPs' personal and professional risk perceptions may be a key to understanding why GPs do not always follow...

  7. Evaluation of a Mobile Phone for Aircraft GPS Interference

    Nguyen, Truong X.

    2004-01-01

    Measurements of spurious emissions from a mobile phone are conducted in a reverberation chamber for the Global Positioning System (GPS) radio frequency band. This phone model was previously determined to have caused interference to several aircraft GPS receivers. Interference path loss (IPL) factors are applied to the emission data, and the outcome compared against GPS receiver susceptibility. The resulting negative safety margins indicate there are risks to aircraft GPS systems. The maximum emission level from the phone is also shown to be comparable with some laptop computer's emissions, implying that laptop computers can provide similar risks to aircraft GPS receivers.

  8. Pricise Target Geolocation Based on Integeration of Thermal Video Imagery and Rtk GPS in Uavs

    Hosseinpoor, H. R.; Samadzadegan, F.; Dadras Javan, F.

    2015-12-01

    There are an increasingly large number of uses for Unmanned Aerial Vehicles (UAVs) from surveillance, mapping and target geolocation. However, most of commercial UAVs are equipped with low-cost navigation sensors such as C/A code GPS and a low-cost IMU on board, allowing a positioning accuracy of 5 to 10 meters. This low accuracy which implicates that it cannot be used in applications that require high precision data on cm-level. This paper presents a precise process for geolocation of ground targets based on thermal video imagery acquired by small UAV equipped with RTK GPS. The geolocation data is filtered using a linear Kalman filter, which provides a smoothed estimate of target location and target velocity. The accurate geo-locating of targets during image acquisition is conducted via traditional photogrammetric bundle adjustment equations using accurate exterior parameters achieved by on board IMU and RTK GPS sensors and Kalman filtering and interior orientation parameters of thermal camera from pre-flight laboratory calibration process.

  9. PRICISE TARGET GEOLOCATION BASED ON INTEGERATION OF THERMAL VIDEO IMAGERY AND RTK GPS IN UAVS

    H. R. Hosseinpoor

    2015-12-01

    Full Text Available There are an increasingly large number of uses for Unmanned Aerial Vehicles (UAVs from surveillance, mapping and target geolocation. However, most of commercial UAVs are equipped with low-cost navigation sensors such as C/A code GPS and a low-cost IMU on board, allowing a positioning accuracy of 5 to 10 meters. This low accuracy which implicates that it cannot be used in applications that require high precision data on cm-level. This paper presents a precise process for geolocation of ground targets based on thermal video imagery acquired by small UAV equipped with RTK GPS. The geolocation data is filtered using a linear Kalman filter, which provides a smoothed estimate of target location and target velocity. The accurate geo-locating of targets during image acquisition is conducted via traditional photogrammetric bundle adjustment equations using accurate exterior parameters achieved by on board IMU and RTK GPS sensors and Kalman filtering and interior orientation parameters of thermal camera from pre-flight laboratory calibration process.

  10. High Precision and Real Time Tracking of Low Earth Orbiters With GPS: Case Studies With TOPEX/POSEIDON and EUVE

    Yunck, Thomas P.; Bertiger, Winy I.; Gold, Kenn; Guinn, Joseph; Reichert, Angie; Watkins, Michael

    1995-01-01

    TOPEX/POSEIDON carries a dual-frequency 6 channel GPS receiver while EUVE has a 12 channel single frequency receiver. Flying at an altitude of 1334 km, TOPEX/POSEIDON performs precise ocean altimetry, which demands the highest possible accuracy in determining the radial orbit component in post-processing. Radial RMS accuracies of about 2 cm were realized using reduced dynamic tracking techniques. In this approach, orbit errors due to force are substantially reduced by exploiting the geometric strength of GPS to solve for a set of stochastic forces. On EUVE, the emphasis was on evaluating real time positioning techniques with a single frequency receiver. The capability for real time 3D accuracies of 15 m in the presence of Selective Availability was shown. This was validated by comparing to a post-processed differential GPS truth orbit believed accurate to about 1 m.!.

  11. Monitoring of D-layer using GPS

    Golubkov, Maxim; Bessarab, Fedor; Karpov, Ivan; Golubkov, Gennady; Manzheliy, Mikhail; Borchevkina, Olga; Kuverova, Veronika; Malyshev, Nikolay; Ozerov, Georgy

    2016-07-01

    Changes in D layer of ionosphere during the periods of high solar activity lead to non-equilibrium two-temperature plasma parameter variations. Accordingly, the population of orbital degenerate states of Rydberg complexes changes in a fraction of a microsecond. In turn, this affects the operation of any of the systems based on the use of GPS radio signals passing through this layer. It is well known that GPS signals undergo the greatest distortion in the altitude range of 60-110 km. Therefore, the analysis of changes in signal intensity can be useful for plasma diagnosis in these altitudes. In particular, it is useful to determine the vertical temperature profiles and electron density. For this purpose, one can use the satellite radio occultation method. This method is widely used in recent years to solve problems of the electron concentration profile recovery in the F-region of the ionosphere, and also for climate problem solutions. This method allows to define the altitude profiles of the GPS signal propagation delays and to obtain from the inverse problem solution qualitatively high-altitude profiles of the quantities using relative measurements. To ensure the authenticity of the found distributions of electron density and temperature in the D region of the ionosphere, the results should be complemented by measurements of the own atmospheric radiation power at frequencies of 1.4 and 5.0 GHz. This ensures control of the reliability of the results obtained using the "Rydberg" code. Monitoring of the state changes in the D layer by repeatedly following at regular intervals GPS satellite measurements are also of great interest and can provide valuable information on the macroscopic dynamics of D layer containing Rydberg complexes and free electrons. For example, one can monitor changes in the thickness of the emitting layer in time. Such changes lead to an additional contribution to the formation of satellite GPS system errors. It should also be noted that the

  12. Reduction in the ionospheric error for a single-frequency GPS timing solution using tomography

    Cathryn N. Mitchell

    2009-06-01

    Full Text Available

    Abstract

    Single-frequency Global Positioning System (GPS receivers do not accurately compensate for the ionospheric delay imposed upon a GPS signal. They rely upon models to compensate for the ionosphere. This delay compensation can be improved by measuring it directly with a dual-frequency receiver, or by monitoring the ionosphere using real-time maps. This investigation uses a 4D tomographic algorithm, Multi Instrument Data Analysis System (MIDAS, to correct for the ionospheric delay and compares the results to existing single and dualfrequency techniques. Maps of the ionospheric electron density, across Europe, are produced by using data collected from a fixed network of dual-frequency GPS receivers. Single-frequency pseudorange observations are corrected by using the maps to find the excess propagation delay on the GPS L1 signals. Days during the solar maximum year 2002 and the October 2003 storm have been chosen to display results when the ionospheric delays are large and variable. Results that improve upon the use of existing ionospheric models are achieved by applying MIDAS to fixed and mobile single-frequency GPS timing solutions. The approach offers the potential for corrections to be broadcast over a local region, or provided via the internet and allows timing accuracies to within 10 ns to be achieved.



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

    Christian Eling

    2015-10-01

    Full Text Available 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.

  14. Real-time single-frequency GPS/MEMS-IMU attitude determination of lightweight UAVs.

    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

  15. GIST A tool for Global Ionospheric Tomography using GPS ground and LEO d ata and sources of opportunity with applications in instrument calibration

    Flores, A; Rius, A; Cardellach, E

    1999-01-01

    Ionospheric tomography using GPS data has been reported in the literature and even the application to radar altimeter calibration was succesfully carried out in a recent work. We here present a new software tool, called Global Ionospheric Stochastic Tomography software (GIST), and its powerful capability for ingesting GPS data from different sources (ground stations, receivers on board LEO for navigation and occultation purposes) and other data such as altimetry data to yield global maps with dense coverage and inherent calibration of the instruments. We show results obtained including 106 IGS ground stations, GPS/MET low rate occultation data, TOPEX/POSEIDON GPS data from the navigation antenna and NASA Radar Altimeter with the additional benefit of a direct estimation of the NRA bias. The possibility of ingesting different kinds of ionospheric data into the tomographic model suggest a way to accurately monitor the ionosphere with direct application to single frequency instrument calibration.

  16. Evaluation of the Effect of Radio Frequency Interference on Global Positioning System (GPS Accuracy via GPS Simulation

    Dinesh Sathyamoorthy

    2012-09-01

    Full Text Available In this study, Global positioning system (GPS simulation is employed to study the effect of radio frequency interference (RFI on the accuracy of two handheld GPS receivers; Garmin GPSmap 60CSx (evaluated GPS receiver and Garmin GPSmap 60CS (reference GPS receiver. Both GPS receivers employ the GPS L1 coarse acquisition (C/A signal. It was found that with increasing interference signal power level, probable error values of the GPS receivers increase due to decreasing carrier-to-noise density (C/N0 levels for GPS satellites tracked by the receivers. Varying probable error patterns are observed for readings taken at different locations and times. This was due to the GPS satellite constellation being dynamic, causing varying GPS satellite geometry over location and time, resulting in GPS accuracy being location/time dependent. In general, the highest probable error values were observed for readings with the highest position dilution of precision (PDOP values, and vice versa.Defence Science Journal, 2012, 62(5, pp.338-347, DOI:http://dx.doi.org/10.14429/dsj.62.1606

  17. Underwater Digital Terrain Model with GPS-aided High-resolution Profile-scan Sonar Images

    ZHOU Yong-jun; KOU Xin-jian

    2008-01-01

    The whole procedures of underwater digital terrain model (DTM) were presented by building with the global positioning system (GPS) aided high-resolution profile-scan sonar images. The algorithm regards the digital image scanned in a cycle as the raw data. First the label rings are detected with the improved Hough transform (HT) method and followed by curve-fitting for accurate location; then the most probable window for each ping is detected with weighted neighborhood gray-level co-occurrence matrix; and finally the DTM is built by integrating the GPS data with sonar data for 3D visualization. The case of an underwater trench for immersed tube road tunnel is illustrated.

  18. In situ treatment of liver using catheter based therapeutic ultrasound with combined imaging and GPS tracking

    Ghoshal, Goutam; Heffter, Tamas; Williams, Emery; Bromfield, Corinne; Salgaonkar, Vasant; Rund, Laurie; Ehrhardt, John M.; Diederich, Chris J.; Burdette, E. Clif

    2013-02-01

    Extensive surgical procedure or liver transplant still remains the gold standard for treating slow-growing tumors in liver. But only few candidates are suitable for such procedure due to poor liver function, tumors in unresectable locations or presence of other liver diseases. In such situations, minimally invasive surgery may be the best therapeutic procedure. The use of RF, laser and ultrasound ablation techniques has gained considerable interest over the past several years to treat liver diseases. The success of such minimally invasive procedure depends on accurately targeting the desired region and guiding the entire procedure. The purpose of this study is to use ultrasound imaging and GPS tracking system to accurately place a steerable acoustic ablator and multiple temperature sensors in porcine liver in situ. Temperature sensors were place at eight different locations to estimate thermal distribution in the three-dimensional treated volume. Acoustic ablator of center frequency of 7 MHz was used for the experiments. During therapy a maximum temperature of 60-65 °C was observed at a distance 8-10 mm from the center of the ablation transducer. The dose distribution was analyzed and compared with the gross pathology of the treated region. Accurate placement of the acoustic applicator and temperature sensors were achieved using the combined image-guidance and the tracking system. By combining ultrasound imaging and GPS tracking system accurate placement of catheter based acoustic ablation applicator can be achieved in livers in situ.

  19. The GPS-gravimetry boundary value problem

    YU; Jinhai; ZHANG; Chuanding

    2005-01-01

    How to determine the earth's external gravity field with the accuracy of O(T2) by making use of GPS data and gravity values measured on the earth's surface is dealt with in this paper. There are two main steps: to extend these measured values on the earth's surface onto the reference ellipsoid at first and then to seek for the integral solution of the external Neumann problem outside the ellipsoid. In addition, the corresponding judging criteria of accuracy to solve the GPS-gravity boundary value problem are established. The integral solution given in the paper not only contains all frequency-spectral information of the gravity field with the accuracy of O(T2),but is also easily computed. In fact, the solution has great significance for both theory and practice.

  20. GPS: El sistema de posicionamiento global

    Juan Gilberto Serpas

    2016-03-01

    Full Text Available El Sistema de Posicionamiento Global (GPS, por sus siglas en inglés se ha convertido, en la actualidad, en una herramienta invaluable para el posicionamiento de puntos sobre la superficie terrestre. Este artículo pretende dar al lector una descripción del GPS, así como la introducción al cálculo de coordenadas para ser usadas tanto en navegación como en labores de topografía y geodesia. Las características principales del sistema son descritas y se introducen los principios básicos para la determinación de coordenadas tanto en modo absoluto como en modo relativo.

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

    Wu Jun

    2011-11-01

    and easy to execute, but was likely less robust than the rule-based model under the condition of biased or poor quality training data. Conclusions Our models can successfully identify indoor and in-vehicle travel points from the raw GPS data, but challenges remain in developing models to distinguish outdoor static points and walking. Accurate training data are essential in developing reliable models in classifying time-activity patterns.

  2. Continuous GPS Network Operating Throughout Ecuador

    Mothes, Patricia A.; Nocquet, Jean-Mathieu; Jarrín, Paul

    2013-06-01

    Recent devastating great earthquakes in Sumatra, Chile, and Japan show that scientists need to learn more about other less studied subduction zones that have also generated major earthquakes in the recent past. On the margin of northwest South America, offshore Ecuador and Colombia, the Nazca plate's rapid oblique subduction beneath the South American continent has produced a sequence of large earthquakes. A recently installed continuous GPS network is beginning to help scientists learn more about the geodynamic framework in Ecuador.

  3. UAV ONBOARD GPS IN POSITIONING DETERMINATION

    K. N. Tahar; Kamarudin, S. S.

    2016-01-01

    The establishment of ground control points is a critical issue in mapping field, especially for large scale mapping. The fast and rapid technique for ground control point’s establishment is very important for small budget projects. UAV onboard GPS has the ability to determine the point positioning. The objective of this research is to assess the accuracy of unmanned aerial vehicle onboard global positioning system in positioning determination. Therefore, this research used UAV onboar...

  4. Global Geodesy Using GPS Without Fiducial Sites

    Heflin, Michael B.; Blewitt, Geoffrey

    1994-01-01

    Global Positioning System, GPS, used to make global geodetic measurements without use of fiducial site coordinates. Baseline lengths and geocentric radii for each site determined without having to fix any site coordinates. Given n globally distributed sites, n baseline lengths and n geocentric radii form polyhedron with each site at vertex and with geocenter at intersection of all radii. Geodetic information derived from structure of polyhedron and its change with time. Approach applied to any global geodetic technique.

  5. Progress of Subsidence Depression monitored by GPS

    Doležalová, Hana; Kajzar, Vlastimil; Staš, Lubomír; Souček, Kamil

    Vol. 1. Sofia: SGEM, 2009, s. 811-814. ISBN 954918181-2. [International Multidisciplinary GeoConference SGEM 2009 /9./ - Modern Management of Mine Producing, Geology and Environmental Protection. Albena (BG), 14.06.2009-20.06.2009] R&D Projects: GA ČR GA105/07/1586 Institutional research plan: CEZ:AV0Z30860518 Keywords : undermining * subsidence depression * GPS * tectonic faults Subject RIV: DH - Mining, incl. Coal Mining

  6. Dual algebraic formulation of differential GPS

    Lannes, A.; Dur, S.

    2003-05-01

    A new approach to differential GPS is presented. The corresponding theoretical framework calls on elementary concepts of algebraic graph theory. The notion of double difference, which is related to that of closure in the sense of Kirchhoff, is revisited in this context. The Moore-Penrose pseudo-inverse of the closure operator plays a key role in the corresponding dual formulation. This approach, which is very attractive from a conceptual point of view, sheds a new light on the Teunissen formulation.

  7. Jammer Impact on Galileo and GPS Receivers

    BORIO DANIELE; O'DRISCOLL CILLIAN; FORTUNY GUASCH Joaquim

    2013-01-01

    Global Navigation Satellite Systems (GNSSs) are vulnerable to several threats including jamming and spoofing. Jamming is the deliberate transmission of powerful Radio-Frequency (RF) signals which can easily overpower the much weaker GNSS components disturbing and, in some cases, denying GNSS operations. In recent years an increasing number of cheap, though illegal, jammers have become commercially available. In this paper, the impact of these jammers on Global Positioning System (GPS) and Gal...

  8. Precise Clock Solutions Using Carrier Phase from GPS Receivers in the International GPS Service

    Zumberge, J. F.; Jefferson, D. C.; Stowers, D. A.; Tjoelker, R. L.; Young, L. E.

    1999-01-01

    As one of its activities as an Analysis Center in the International GPS Service (IGS), the Jet Propulsion Laboratory (JPL) uses data from a globally distributed network of geodetic-quality GPS receivers to estimate precise clock solutions, relative to a chosen reference, for both the GPS satellites and GPS receiver internal clocks, every day. The GPS constellation and ground network provide geometrical strength resulting in formal errors of about 100 p sec for these estimates. Some of the receivers in the global IGS network contain high quality frequency references, such as hydrogen masers. The clock solutions for such receivers are smooth at the 20-p sec level on time scales of a few minutes. There are occasional (daily to weekly) shifts at the microsec level, symptomatic of receiver resets, and 200-p sec-level discontinuities at midnight due to 1-day processing boundaries. Relative clock solutions among 22 IGS sites proposed as "fiducial" in the IGS/BIPM pilot project have been examined over a recent 4-week period. This allows a quantitative measure of receiver reset frequency as a function of site. For days and-sites without resets, the Allan deviation of the relative clock solutions is also computed for subdaily values of tau..

  9. Cleaning HI Spectra Contaminated by GPS RFI

    Sylvia, Kamin; Hallenbeck, Gregory L.; Undergraduate ALFALFA Team

    2016-01-01

    The NUDET systems aboard GPS satellites utilize radio waves to communicate information regarding surface nuclear events. The system tests appear in spectra as RFI (radio frequency interference) at 1381MHz, which contaminates observations of extragalactic HI (atomic hydrogen) signals at 50-150 Mpc. Test durations last roughly 20-120 seconds and can occur upwards of 30 times during a single night of observing. The disruption essentially renders the corresponding HI spectra useless.We present a method that automatically removes RFI in HI spectra caused by these tests. By capitalizing on the GPS system's short test durations and predictable frequency appearance we are able to devise a method of identifying times containing compromised data records. By reevaluating the remaining data, we are able to recover clean spectra while sacrificing little in terms of sensitivity to extragalactic signals. This method has been tested on 500+ spectra taken by the Undergraduate ALFALFA Team (UAT), in which it successfully identified and removed all sources of GPS RFI. It will also be used to eliminate RFI in the upcoming Arecibo Pisces-Perseus Supercluster Survey (APPSS).This work has been supported by NSF grant AST-1211005.

  10. GPS and Injury Prevention in Professional Soccer.

    Ehrmann, Fabian E; Duncan, Craig S; Sindhusake, Doungkamol; Franzsen, William N; Greene, David A

    2016-02-01

    Ehrmann, FE, Duncan, CS, Sindhusake, D, Franzsen, WN, and Greene, DA. GPS and injury prevention in professional soccer. J Strength Cond Res 30(2): 360-367, 2016-This study investigated the relationship between GPS variables measured in training and gameplay and injury occurrences in professional soccer. Nineteen professional soccer players competing in the Australian Hyundai A-League were monitored for 1 entire season using 5 Hz Global Positioning System (GPS) units (SPI-Pro GPSports) in training sessions and preseason games. The measurements obtained were total distance, high-intensity running distance, very-high-intensity running distance, new body load, and meters per minute. Noncontact soft tissue injuries were documented throughout the season. Players' seasons were averaged over 1- and 4-week blocks according to when injuries occurred. These blocks were compared with each other and with players' seasonal averages. Players performed significantly higher meters per minute in the weeks preceding an injury compared with their seasonal averages (+9.6 and +7.4% for 1- and 4-week blocks, respectively) (p training and gameplay intensity leading up to injuries. Furthermore, injury blocks showed significantly lower average new body load compared with seasonal averages (-15.4 and -9.0% for 1- and 4-week blocks, respectively) (p injuries for coaches and sports scientists to consider when planning and monitoring training. PMID:26200191