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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

    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.

  11. 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.

  12. 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.

  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. 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

  1. 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.

  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 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...

  10. 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.

  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. 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.

  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. 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...

  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. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  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. 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...

  19. 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...

  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. 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.

  3. 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.

  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. 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.

  9. 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.

  10. 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...

  11. 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....

  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. 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...

  14. 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...

  15. 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.

  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. 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...

  7. 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...

  8. 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...

  9. 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...

  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. 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.

  13. 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.

  14. 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.

  15. 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

  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. 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 ...

  11. 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.

  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. 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.

  18. 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

  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. 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...

  4. 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

  5. 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

  6. 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....

  7. 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.

  8. 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.

  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. 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.

  1. 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.

  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 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...

  13. 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.

  14. 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...

  15. 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...

  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. 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.

  19. 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.

  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. 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.

  4. 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.

  5. 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.

  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. 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.

  10. 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...

  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. 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.

  13. 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...

  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. 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

  16. 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

  17. 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

  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. 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...

  7. 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.

  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

    2012-11-01

    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

  10. 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

  11. 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.

  12. 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.

  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. 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...

  18. 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...

  19. 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.

  20. 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

  1. 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…

  2. 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...

  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. 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...

  6. 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.

  7. 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.

  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. 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.

  19. 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.

  20. 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.

  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. 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.

  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. 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...

  5. 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.

  6. 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.

  7. 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

  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

  11. The performance of GPS time and frequency transfer: comment on ‘A detailed comparison of two continuous GPS carrier-phase time transfer techniques’

    Petit, Gérard; Defraigne, Pascale

    2016-06-01

    The paper ‘A detailed comparison of two continuous GPS carrier-phase time transfer techniques’ (Yao et al 2015 Metrologia 52 666) presents the revised RINEX-shift (RRS) method, a technique using ‘classical precise point positioning (PPP)’ solutions on sliding batches and aiming at providing continuous time links. The authors claim the superiority of the RRS technique with respect to ‘classical PPP’ in terms of frequency stability and solving for discontinuities due to data gaps. It is shown here that these conclusions do not rely on physical principles, and are erroneous as they are driven by misinterpreted or corrupted PPP solutions. Using state-of-the-art PPP computation on the same data sets used in Yao et al’s paper (2015 Metrologia 52 666), we show that the stability of RRS is at best similar to that of ‘classical PPP’ (within statistical uncertainties). Furthermore, the RRS method of removing discontinuities in case of data gaps by interpolating the phase data should not be applied systematically as it can cause erroneous clock solutions when the data gaps are associated with a true phase discontinuity.

  12. GPS/CAPS dual-mode software receiver

    2009-01-01

    The positioning of the GPS or Chinese Area Positioning System (CAPS) software receiver was developed on a software receiver platform. The structure of the GPS/CAPS dual-mode software receiver was put forward after analyzing the differences in the satellite identification, ranging code, spread spectrum, coordinate system, time system, carrier band, and navigation data between GPS and CAPS. Based on Matlab software on a personal computer, baseband signal processing and positioning procedures were completed using real GPS and CAPS radio frequency signals received by two antennas. Three kinds of experiments including GPS positioning, CAPS positioning, and GPS/CAPS positioning were carried out. Stability and precision of the results were analyzed and compared. The experimental results show that the precision of CAPS is similar to that of GPS, while the positioning precision of the GPS/CAPS dual-mode software receiver is 1-2 m higher than that of CAPS or GPS. The smallest average variance of the positioning can be obtained by using the GPS/CAPS dual-mode software receiver.

  13. Towards accurate emergency response behavior

    Nuclear reactor operator emergency response behavior has persisted as a training problem through lack of information. The industry needs an accurate definition of operator behavior in adverse stress conditions, and training methods which will produce the desired behavior. Newly assembled information from fifty years of research into human behavior in both high and low stress provides a more accurate definition of appropriate operator response, and supports training methods which will produce the needed control room behavior. The research indicates that operator response in emergencies is divided into two modes, conditioned behavior and knowledge based behavior. Methods which assure accurate conditioned behavior, and provide for the recovery of knowledge based behavior, are described in detail

  14. GPS error and its effects on movement analysis

    Ranacher, Peter; Van der Spek, Stefan Christiaan; Reich, Siegfried

    2015-01-01

    Global Navigation Satellite Systems (GNSS), such as the Global Positioning System (GPS), are among the most important sensors in movement analysis. GPS data loggers are widely used to record the movement trajectories of vehicles, animals or human beings. However, these trajectories are inevitably affected by GPS measurement error, which influences conclusion drawn about the behavior of the moving objects. In this paper we investigate GPS measurement error and discuss its influence on movement parameters such as speed, direction or distance. We identify three characteristic properties of GPS measurement error: it follows temporal (1) and spatial (2) autocorrelation and causes a systematic overestimation of distances (3). Based on our findings we give recommendations on how to collect movement data in order to minimize the influence of error. We claim that these recommendations are essential for designing an appropriate sampling strategy for collecting movement data by means of a GPS.

  15. Continuing medical education and burnout among Danish GPs

    Brøndt, Anders; Sokolowski, Ineta; Olesen, Frede;

    2008-01-01

    BACKGROUND: There has been minimal research into continuing medical education (CME) and its association with burnout among GPs. AIM: The aim of this study was to investigate the association between participating in CME and experiencing burnout in a sample of Danish GPs. DESIGN OF STUDY: Cross......-sectional questionnaire study. SETTING: All 458 active GPs in 2004, in the County of Aarhus, Denmark were invited to participate. METHOD: Data on CME activities were obtained for all GPs and linked to burnout which was measured using the Maslach Burnout Inventory - Human Services Survey. The relationship between CME...... activity and burnout was calculated as prevalence ratios (PR) in a generalised linear model. RESULTS: In total, 379 (83.5%) GPs returned the questionnaire. The prevalence of burnout was about 25%, and almost 3% suffered from 'high burnout'. A total of 344 (92.0%) GPs were members of a CME group or a...

  16. GPS operations at Olkiluoto, Kivetty and Romuvaara in 2010

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

    2011-11-15

    The Finnish Geodetic Institute (FGI) has studied crustal deformations in co-operation with the Posiva Oy since 1994, when a network of ten pillars for GPS observations was established at Olkiluoto. In 2010 the local GPS network at Olkiluoto consisted of 14 concrete pillars. The whole network has been measured twice a year in the static GPS campaigns with 24 h sessions. The four new pillars were established in 2010 and the permanent measurements on them will start in 2011. The network of seven GPS pillars was built at Kivetty and Romuvaara during the year 1996. One pillar in each investigation area belongs to the Finnish permanent GPS network, FinnRef. A total of 28 GPS measurement campaigns have been carried out at Olkiluoto since 1995, and 18 campaigns at Kivetty and Romuvaara. At Olkiluoto a baseline for electronic distance measurements (EDM) was built in 2002. The baseline has been measured in connection to the GPS observations using the EDM instrument Kern ME5000 Mekometer. The GPS operations in 2010 included the two GPS campaigns at Olkiluoto, GPS campaigns at Kivetty and Romuvaara, EDM baseline measurements at Olkiluoto, and the control marker measurements with the tachymeter at Olkiluoto. All GPS data history was reprocessed with Bernese GPS software using the new processing strategy tested in 2009. The results were analysed by computing the change rates of the baselines and estimating horizontal velocities for the pillars using the barycenter of the velocities as a reference. In the Olkiluoto inner network 80 percent of the change rates were smaller than 0.10 mm/a. Roughly one fourth of the change rates could be considered as statistically significant (change rate larger than 3 {sigma}. The statistically significant change rates were mainly related to the Olkiluoto permanent station (GPS1) and to the pillar GPS5, which had also the maximum change rate (0.21 {+-} 0.03 mm/a). In Olkiluoto outer network the maximum and statistically significant change rates

  17. Accurate determination of antenna directivity

    Dich, Mikael

    1997-01-01

    The derivation of a formula for accurate estimation of the total radiated power from a transmitting antenna for which the radiated power density is known in a finite number of points on the far-field sphere is presented. The main application of the formula is determination of directivity from power...

  18. Fast precise GPS positioning in the presence of ionospheric delays

    Odijk, D.

    2002-01-01

    In many geodetic (surveying) applications positions of points in the terrain need to be determined with high precision (cm-accuracy or even better). The Global Positioning System (GPS) is very suitable for this purpose. High positioning accuracy is in principle feasible when a relative measurement setup is used and in the processing procedure certain systematic errors in the GPS observations are properly taken into account. The largest of these errors is due to the propagation of the GPS sign...

  19. Launch strategy for a GPS-based package tracker product

    Biermann, Jürgen

    2006-01-01

    The objective of this paper is to present a recommendation for a launch strategy for a new Package Tracker Product based on enhanced GPS location technology for a GPS software company, Guardian Mobile Monitoring Systems. We will first give an overview of Global Positioning System (GPS) technology and its more recent advancements and explain the potential for a package tracker product. Secondly, we will examine possible target market segments. Thirdly, we will perform an internal analysis of G...

  20. GPS technology to monitoring auto transport in Latvia

    Victor Boicov

    2014-01-01

    Full Text Available This paper is the result of authors’ activities in the field of research and implementation of global positioning system (GPS technologies in the Latvian car industry. The subject of study is the characteristics of Latvian auto transport management. Topicality and importance of this issue are related with new GPS applications to auto transport monitoring. Principal practical application of this paper is reflected in the methodology developed by the authors in order to design, elaborate and introduce GPS systems.

  1. Hybrid GPS-GSM Localization of Automobile Tracking System

    Mohammad A. Al-Khedher

    2012-01-01

    An integrated GPS-GSM system is proposed to track vehicles using Google Earth application. The remote module has a GPS mounted on the moving vehicle to identify its current position, and to be transferred by GSM with other parameters acquired by the automobile's data port as an SMS to a recipient station. The received GPS coordinates are filtered using a Kalman filter to enhance the accuracy of measured position. After data processing, Google Earth application is used to view the current loca...

  2. Method and apparatus for relative navigation using reflected GPS signals

    Cohen, Ian R. (Inventor); Boegner, Jr., Gregory J. (Inventor)

    2010-01-01

    A method and system to passively navigate an orbiting moving body towards an orbiting target using reflected GPS signals. A pair of antennas is employed to receive both direct signals from a plurality of GPS satellites and a second antenna to receive GPS signals reflected off an orbiting target. The direct and reflected signals are processed and compared to determine the relative distance and position of the orbiting moving body relative to the orbiting target.

  3. INS/GPS Integrated Navigation Technology for Hypersonic UAV

    Nana Meng; Shunan Wu; Hongtu Ma; Wenya Zhou

    2013-01-01

    INS/GPS integrated navigation system is studied in this paper for the hypersonic UAV in order to satisfy the precise guidance requirements of hypersonic UAV and in response to the defects while the inertial navigation system (INS) and the global positioning system (GPS) are being applied separately. The information of UAV including position, velocity and attitude can be obtained by using INS and GPS respectively after generating a reference trajectory. The corresponding errors of two navigati...

  4. Arctic glacier movement monitoring with GPS method on 2005

    Ai Songtao; E Dongchen; Yan Ming; Ren Jiawen

    2006-01-01

    During the 2005 Arctic Yellow River Station expedition, the research on monitoring the movement and mass balance of two glaciers around Ny-Alesund,Station expedition were conducted. This paper analyzes the feasibility and advantage in using GPS method to monitor the Arctic glaciers'movement, estimates the precision of first time measured GPS data and discusses the relevant problems in surveying on the Arctic Glaciers with GPS.

  5. Patterns of GPS measured time outdoors after school and objective physical activity in English children: the PEACH project

    Griew Pippa

    2010-04-01

    Full Text Available Abstract Background Observational studies have shown a positive association between time outdoors and physical activity in children. Time outdoors may be a feasible intervention target to increase the physical activity of youth, but methods are required to accurately measure time spent outdoors in a range of locations and over a sustained period. The Global Positioning System (GPS provides precise location data and can be used to identify when an individual is outdoors. The aim of this study was to investigate whether GPS data recorded outdoors were associated with objectively measured physical activity. Methods Participants were 1010 children (11.0 ± 0.4 years recruited from 23 urban primary schools in South West England, measured between September 2006 and July 2008. Physical activity was measured by accelerometry (Actigraph GT1M and children wore a GPS receiver (Garmin Foretrex 201 after school on four weekdays to record time outdoors. Accelerometer and GPS data were recorded at 10 second epochs and were combined to describe patterns of physical activity when both a GPS and accelerometer record were present (outdoors and when there was accelerometer data only (indoors. ANOVA was used to investigate gender and seasonal differences in the patterns of outdoor and indoor physical activity, and linear regression was used to examine the cross-sectional associations between GPS-measured time outdoors and physical activity. Results GPS-measured time outdoors was a significant independent predictor of children's physical activity after adjustment for potential confounding factors. Physical activity was more than 2.5 fold higher outdoors than indoors (1345.8 ± 907.3 vs 508.9 ± 282.9 counts per minute; F = 783.2, p Conclusions Duration of GPS recording is positively associated with objectively measured physical activity and is sensitive to seasonal differences. Minute by minute patterning of GPS and physical activity data is feasible and may be a

  6. GPS Antenna Characterization Experiment (ACE): Receiver Design and Initial Results

    Martzen, Phillip; Highsmith, Dolan E.; Valdez, Jennifer E.; Parker, Joel J. K.; Moreau, Michael C.

    2015-01-01

    The GPS Antenna Characterization Experiment (ACE) is a research collaboration between Aerospace and NASA Goddard to characterize the gain patterns of the GPS L1 transmit antennas. High altitude GPS observations are collected at a ground station through a transponder-based or "bent-pipe" architecture where the GPS L1 RF spectrum is received at a platform in geosynchronous orbit and relayed to the ground for processing. The focus of this paper is the unique receiver algorithm design and implementation. The high-sensitivity GPS C/A-code receiver uses high fidelity code and carrier estimates and externally supplied GPS message bit data in a batch algorithm with settings for a 0 dB-Hz threshold. The resulting carrier-to-noise measurements are used in a GPS L1 transmit antenna pattern reconstruction. This paper shows initial transmit gain patterns averaged over each block of GPS satellites, including comparisons to available pre-flight gain measurements from the GPS vehicle contractors. These results provide never-before-seen assessments of the full, in-flight transmit gain patterns.

  7. GPS/CAPS dual-mode software receiver

    NING ChunLin; SHI HuLi; HU Chao

    2009-01-01

    The positioning of the GPS or Chinese Area Positioning System (CAPS) software receiver was developed on a software receiver platform.The structure of the GPSlCAPS dual-mode software receiver was put forward after analyzing the differences in the satellite identification,ranging code,spread spectrum,coordinate system,time system,carrier band,and navigation data between GPS and CAPS.Based on Matlab software on a personal computer,baseband signal processing and positioning procedures were completed using real GPS and CAPS radio frequency signals received by two antennas.Three kinds of experiments including GPS positioning,CAPS positioning,and GPS/CAPS positioning were carried out.Stability and precision of the results were analyzed and compared.The experimental results show that the precision of CAPS is similar to that of GPS,while the positioning precision of the GPS/CAPS dual-mode software receiver is 1-2 m higher than that of CAPS or GPS.The smallest average variance of the positioning can be obtained by using the GPS/CAPS dual-mode software receiver.

  8. Kalman Filtering USNO's GPS Observations for Improved Time Transfer Predictions

    Hutsell, Steven T.

    1996-01-01

    The Global Positioning System (GPS) Master Control Station (MCS) performs the Coordinated Universal Time (UTC) time transfer mission by uploading and broadcasting predictions of the GPS-UTC offset in subframe 4 of the GS navigation message. These predictions are based on only two successive daily data points obtained from the US Naval Observatory (USNO). USNO produces these daily smoothed data points by performing a least-squares fit on roughly 38 hours worth of data from roughly 160 successive 13-minute tracks of GPS satellites. Though sufficient for helping to maintain a time transfer error specification of 28 ns (1 Sigma), the MCS's prediction algorithm does not make the best use of the available data from from USNO, and produces data that can degrade quickly over extended prediction spans. This paper investigates how, by applying Kalman filtering to the same available tracking data, the MCS could improve its estimate of GPS-UTC, and in particular, the GPS-UTC A(sub 1) term. By refining the A(sub 1) (frequency) estimate for GPS-UTC predictions, error in GPS time transfer could drop significantly. Additional, the risk of future spikes in GPS's time transfer error could similarly be minimized, by employing robust Kalman filtering for GPS-UTC predictions.

  9. Analysis of Adverse Events in Identifying GPS Human Factors Issues

    Adams, Catherine A.; Hwoschinsky, Peter V.; Adams, Richard J.

    2004-01-01

    The purpose of this study was to analyze GPS related adverse events such as accidents and incidents (A/I), Aviation Safety Reporting System (ASRS) reports and Pilots Deviations (PDs) to create a framework for developing a human factors risk awareness program. Although the occurrence of directly related GPS accidents is small the frequency of PDs and ASRS reports indicated there is a growing problem with situational awareness in terminal airspace related to different types of GPs operational issues. This paper addresses the findings of the preliminary research and a brief discussion of some of the literature on related GPS and automation issues.

  10. Uporaba satelitskih sistemov GPS in GLONASS v geodetski izmeri

    Oset, Klemen

    2015-01-01

    V geodetski izmeri GNSS se že nekaj časa za določanje položaja uporabljata hkrati sistema GLONASS in GPS. V diplomski nalogi sta predstavljena GNSS sistema GPS in GLONASS, podobnosti in razlike obeh sistemov ter njune značilnosti pri določitvi položaja. V praktičnem delu naloge so predstavljeni potek meritev, obdelava opazovanj in analiza kakovosti koordinat določenih na osnovi opazovanj GPS, opazovanj GLONASS in skupne uporabe opazovanj GPS in GLONASS.

  11. GPS operations at Olkiluoto, Kivetty and Romuvaara in 2006

    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. The network of seven GPS pillars was built at Kivetty and Romuvaara during the year 1996. One pillar in each investigation area belongs to the Finnish permanent GPS network, FinnRef. 22 GPS measurement campaigns have been carried out at Olkiluoto since 1995, and 15 campaigns at Kivetty and Romuvaara. 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 ± 0.22 mm/a. The networks of Kivetty and Romuvaara are quite stabile expect one pillar at Romuvaara. 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 (maximum velocity is -0.23 mm/a ± 0.023 mm/a). The uniform scale for the GPS measurements made in different years is the basic condition for reliable results in the deformation analyses. At Olkiluoto a baseline for electronic distance measurements (EDM) was built in 2002. The baseline has been measured using EDM instruments simultaneously with the GPS observations. The comparison between the GPS and EDM results can solve a possible scale error of the GPS. 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, but the time series are still too short for reliable deformation studies. The local crustal deformations have been studied in GeoSatakunta project, too. This

  12. GPS operations at Olkiluoto, Kivetty and Romuvaara in 2006

    Ahola, J.; Koivula, H.; Poutanen, M.; Jokela, J. (Finnish Geodetic Institute, Masala (FI))

    2007-05-15

    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. The network of seven GPS pillars was built at Kivetty and Romuvaara during the year 1996. One pillar in each investigation area belongs to the Finnish permanent GPS network, FinnRef. 22 GPS measurement campaigns have been carried out at Olkiluoto since 1995, and 15 campaigns at Kivetty and Romuvaara. 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 +- 0.22 mm/a. The networks of Kivetty and Romuvaara are quite stabile expect one pillar at Romuvaara. 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 (maximum velocity is -0.23 mm/a +- 0.023 mm/a). The uniform scale for the GPS measurements made in different years is the basic condition for reliable results in the deformation analyses. At Olkiluoto a baseline for electronic distance measurements (EDM) was built in 2002. The baseline has been measured using EDM instruments simultaneously with the GPS observations. The comparison between the GPS and EDM results can solve a possible scale error of the GPS. 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, but the time series are still too short for reliable deformation studies. The local crustal deformations have been studied in GeoSatakunta project, too. This

  13. 基于EVT的GPS RTK接收机研制%Development of GPS RTK Receiver Based on EVT

    聂志锋; 过静珺

    2003-01-01

    本文介绍了GPS RTK接收机的主要结构及其通讯功能,重点阐述Windows CE编程的主要特点和编制接收机程序的关键技术.论证了运行Windows CE的PDA结合GPS OEM板可以开发性能优越的GPS RTK接收机的可行性.

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

    Kenji Oguni

    2013-12-01

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

  15. Some Considerations in Designing a GPS Pseudolite

    Rapinski, J.; Koziar, M.; Rzepecka, Z.; Cellmer, S.; Chrzanowski, A.

    2012-01-01

    Pseudolites are transmitters of GPS-like signals placed on the ground. Though pseudolites are well known devices and have already been used in the project where visibility to the GNSS satellites is limited, there are still many issues that need enhancement. A prototype of a low-cost pseudolite is being designed and assembled at the University of Warmia and Mazury. This will allow for conducting tests with various codes, signals and software. The goal of the project is to apply the pseudolite as an augmentation to GNSS positioning tasks in geodetic engineering projects. Some practical considerations crucial for the design are discussed in this paper.

  16. Early Detection of Tsunami Scales using GPS

    Song, Y.

    2013-12-01

    This talk reviews how tsunamis form from earthquakes and how GPS technologies can be used to detect tsunami energy scales in real time. Most tsunami fatalities occur in near-field communities of earthquakes at offshore faults. Tsunami early warning is key for reducing the number of fatalities. Unfortunately, an earthquake's magnitude often does not gauge the resulting tsunami power. Here we show that real-time GPS stations along coastlines are able to detect seafloor motions due to big earthquakes, and that the detected seafloor displacements are able to determine tsunami energy and scales instantaneously for early warnings. Our method focuses on estimating tsunami energy directly from seafloor motions because a tsunami's potential or scale, no matter how it is defined, has to be proportional to the tsunami energy. Since seafloor motions are the only source of a tsunami, their estimation directly relates to the mechanism that generates tsunamis; therefore, it is a proper way of identifying earthquakes that are capable of triggering tsunamis, while being able to discriminate those particular earthquakes from false alarms. Examples of detecting the tsunami energy scales for the 2004 Sumatra M9.1 earthquake, the 2005 Nias M8.7 earthquake, the 2010 M8.8 Chilean earthquake, and the 2011 M9.0 Tohoku-Oki earthquake will be presented. Related reference: 1. Xu, Z. and Y. T. Song (2013), Combining the all-source Green's functions and the GPS-derived source for fast tsunami prediction - illustrated by the March 2011 Japan tsunami, J. Atmos. Oceanic Tech., jtechD1200201. 2. Song, Y. T., I. Fukumori, C. K. Shum, and Y. Yi (2012), Merging tsunamis of the 2011 Tohoku-Oki earthquake detected over the open ocean, Geophys. Res. Lett., doi:10.1029/2011GL050767. 3. Song, Y. T. and S.C. Han (2011) Satellite observations defying the long-held tsunami genesis theory, D.L. Tang (ed.), Remote Sensing of the Changing Oceans, DOI 10.1007/978-3-642-16541-2, Springer-Verlag Berlin Heidelberg

  17. Nuclear-Powered GPS Spacecraft Design Study

    Raab, Bernard

    1977-05-01

    This is the final report of a study to investigate the potential benefits of a nuclear (radioisotope) - powered satellite for advanced phases of the Global Positioning System (GPS) program. The critical parameters were: power to user; mean mission duration; orbital predictability; thermal control of on-board frequency standards; and vulnerability. The reference design approach is described, and input data are given for two power systems that are under development: an organic Rankine system and a Brayton cycle system. Reference design details are provided and structural design and analysis are discussed, as well as thermal design and analysis. A higher altitude version is also considered.

  18. Topo-Iberia GPS network: installation complete

    Khazaradze, G.

    2009-04-01

    As part of the project, titled "Geociencias en Iberia: Estudios integrados de topografía y evolución 4D: Topo-Iberia", we have established a network of 26 continuous GPS stations, covering the Spanish part of the Iberian Peninsula (22 stations) and Morocco (4 stations). A major objective behind the establishment of this array is to monitor millimeter level deformation of the crust due to the collision of African and Eurasian (including Iberian) tectonic plates. More specific goals of the project include the identification of the areas and/or specific seismic faults which exhibit higher deformation rates, which could imply an increased seismic hazard in these specific areas. The network has been designed as two X-shaped transects crossing the peninsula from NE to SW and NW to SE, with relatively coarse distribution of the stations, superimposed with denser coverage in the seismically active areas of the Betics, Pyrenees and Cantabrian chains. The majority of the built monuments consist of 1.5-1.8 m tall concrete pillars of 40 cm in diameter anchored to the bedrock using iron rebars. One station in Huesca was built according the UNAVCO's short drilled braced monument (SDBM) specifications. All the monuments were equipped with the SCIGN leveling mounts to ensure the precise antenna alignment and re-alignment in case of the antenna replacement, as well as, tamper resistance of the monument mark. In places were the snow accumulation was possible the antennas were covered with plastic radomes. The instrumentation used is Trimble NetRS dual-frequency receivers with choke-ring antennas. The communication is mainly via cellular telephone system. As of December 2008, the network installation has been competed and all the stations are fully operational. Here we report the milestones of the installation of the network and, as well as, present the first preliminary results of the analysis of the data. Besides the newly established Topo-Iberia CGPS stations, we have included

  19. GPS-Supported Visual SLAM with a Rigorous Sensor Model for a Panoramic Camera in Outdoor Environments

    Ryosuke Shibasaki; Yulin Duan; Zhongchao Shi; Shunping Ji; Yun Shi

    2012-01-01

    Accurate localization of moving sensors is essential for many fields, such as robot navigation and urban mapping. In this paper, we present a framework for GPS-supported visual Simultaneous Localization and Mapping with Bundle Adjustment (BA-SLAM) using a rigorous sensor model in a panoramic camera. The rigorous model does not cause system errors, thus representing an improvement over the widely used ideal sensor model. The proposed SLAM does not require additional restrictions, such as loop ...

  20. A novel map-matching procedure for low-sampling GPS data with applications to traffic flow analysis

    Giovannini, Luca

    2011-01-01

    An extensive sample (2%) of private vehicles in Italy are equipped with a GPS device that periodically measures their position and dynamical state for insurance purposes. Having access to this type of data allows to develop theoretical and practical applications of great interest: the real-time reconstruction of traffic state in a certain region, the development of accurate models of vehicle dynamics, the study of the cognitive dynamics of drivers. In order for these applications to be pos...

  1. Using GPS/INS data to enhance image matching for real-time aerial triangulation

    Tanathong, Supannee; Lee, Impyeong

    2014-11-01

    Direct georeferencing is a promising technique for determining the exterior orientation parameters (EO) of a camera in real-time through the integration of GPS/INS sensors. Instead of using expensive devices, we improve the accuracy of the directly measured EOs through aerial triangulation (AT) and rely on tie-points. In this work, using GPS/INS data, we enhance the KLT tracker to achieve accuracy and speed that is compatible with real-time aerial triangulation. Given GPS/INS data from medium-grade sensors, the proposed system is 48% faster than the original work and tie-points extracted by our system are 6.33% more accurate and more evenly distributed than tie-points extracted by the original work. The AT processing results show that tie-points from the proposed work can reduce the RMSE of the directly measured EOs by 17.87% for position and 23.37% for attitude. Thus, we conclude that our proposed system can be integrated with real-time aerial triangulation.

  2. GPS-Based Daily Context Recognition for Lifelog Generation Using Smartphone

    Go Tanaka

    2015-02-01

    Full Text Available Mobile devices are becoming increasingly more sophisticated with their many diverse and powerful sensors, such as GPS, acceleration, and gyroscope sensors. They provide numerous services for supporting daily human life and are now being studied as a tool to reduce the worldwide increase of lifestyle-related diseases. This paper describes a method for recognizing the contexts of daily human life by recording a lifelog based on a person’s location. The proposed method can distinguish and recognize several contexts at the same location by extracting features from the GPS data transmitted from smartphones. The GPS data are then used to generate classification models by machine learning. Five classification models were generated: a mobile or stationary recognition model, a transportation recognition model, and three daily context recognition models. In addition, optimal learning algorithms for machine learning were determined. The experimental results show that this method is highly accurate. As examples, the F-measure of the daily context recognition was approximately 0.954 overall at a tavern and approximately 0.920 overall at a university .

  3. A Novel Method for Precise Onboard Real-Time Orbit Determination with a Standalone GPS Receiver.

    Wang, Fuhong; Gong, Xuewen; Sang, Jizhang; Zhang, Xiaohong

    2015-01-01

    Satellite remote sensing systems require accurate, autonomous and real-time orbit determinations (RTOD) for geo-referencing. Onboard Global Positioning System (GPS) has widely been used to undertake such tasks. In this paper, a novel RTOD method achieving decimeter precision using GPS carrier phases, required by China's HY2A and ZY3 missions, is presented. A key to the algorithm success is the introduction of a new parameter, termed pseudo-ambiguity. This parameter combines the phase ambiguity, the orbit, and clock offset errors of the GPS broadcast ephemeris together to absorb a large part of the combined error. Based on the analysis of the characteristics of the orbit and clock offset errors, the pseudo-ambiguity can be modeled as a random walk, and estimated in an extended Kalman filter. Experiments of processing real data from HY2A and ZY3, simulating onboard operational scenarios of these two missions, are performed using the developed software SATODS. Results have demonstrated that the position and velocity accuracy (3D RMS) of 0.2-0.4 m and 0.2-0.4 mm/s, respectively, are achieved using dual-frequency carrier phases for HY2A, and slightly worse results for ZY3. These results show it is feasible to obtain orbit accuracy at decimeter level of 3-5 dm for position and 0.3-0.5 mm/s for velocity with this RTOD method. PMID:26690149

  4. Fusion of data from GPS receivers based on a multi-sensor Kalman filter

    Marcin MĄKA

    2008-01-01

    Full Text Available In the age of continually developing satellite navigation practically every ship is equipped with GPS receivers, providing the coordinates of her position. However, relying solely on the navigational data from one autonomous receiver the navigator may expect that a given position is burdened with significant errors or that the position data will be lost. This results from the shortcoming of GPS systems which are susceptible to disturbances affecting their operation. One method to substantially reduce such risk is a navigational system that makes use of a number of sources for accurate position determination. The obtained data are processed, which involves data integration and filtration in order to further diminish measurement errors. One possible solution is the application of a system based on an algorithm of multi-sensor navigational data fusion using a Kalman filter. After a brief description of the algorithm, this article presents some results of the fusion of data from parallel position measurements, where the data come from two mobile GPS receivers. The said solution is intended to be implemented in a navigational decision support system on board a sea-going vessel.

  5. Optimal Methods of RTK-GPS/Accelerometer Integration to Monitor the Displacement of Structures

    Sungnam Hong

    2012-01-01

    Full Text Available The accurate measurement of diverse displacements of structures is an important index for the evaluation of a structure’s safety. In this study, a comparative analysis was conducted to determine the integrated RTK-GPS/accelerometer method that can provide the most precise structure displacement measurements. For this purpose, three methods of calculating the dynamic displacements from the acceleration data were comparatively analyzed. In addition, two methods of determining dynamic, static, and quasi-static displacements by integrating the displacements measured from the RTK-GPS system and the accelerometer were also comparatively analyzed. To ensure precise comparison results, a cantilever beam was manufactured onto which diverse types of displacements were generated to evaluate the measurement accuracy by method. Linear variable differential transformer (LVDT measurements were used as references for the evaluation to ensure accuracy. The study results showed that the most suitable method of measuring the dynamic displacement with the accelerometer was to calculate the displacement by filtering and double-integrating the acceleration data using the FIR band-pass filter. The integration method that uses frequency-based displacement extraction was most appropriate for the integrated RTK-GPS/accelerometer method of comprehensively measuring the dynamic, static, and quasi-static displacements.

  6. GANDER: Commercial Ocean Wave Height Monitoring Service using GPS Reflectometry from Nano-Satellites

    Stephens, Paul; Unwin, Martin; Sweeting, Martin, , Sir

    Ocean storms cause damage to shipping costing over 2.5 billion p.a. in insurance claims. At the same time many thousands of lives are lost every year at sea. The GANDER programme, developed by Satellite Observing Systems Ltd. and Surrey Satellite Technology Ltd. in the UK, aims to provide accurate and timely data to shipping regarding wind speed and wave heights, with the intention of reducing operational costs and improving the efficiency and safety of commercial shipping. The original concept for GANDER was based upon a constellation of sixteen 100kg microsatellites in low Earth orbit, actively measuring sea surface conditions with an altimeter radar. This paper describes the development of a new method using passive GPS reflectometry for the measurement of sea-surface roughness and thus wave height. The GPS instrument offers significant advantages in power consumption, size and weight which enable the mission to be carried out using small 10kg nanosatellites at a greatly reduced cost, thus enhancing the commercial viability of GANDER. This paper presents a description of the constellation of nanosatellites carrying GPS receivers with directional antennas. It explores the economic benefits of GANDER and discusses the advantages and disadvantages of the new technical solution.

  7. Center of Mass Estimation for a Spinning Spacecraft Using Doppler Shift of the GPS Carrier Frequency

    Sedlak, Joseph E.

    2016-01-01

    A sequential filter is presented for estimating the center of mass (CM) of a spinning spacecraft using Doppler shift data from a set of onboard Global Positioning System (GPS) receivers. The advantage of the proposed method is that it is passive and can be run continuously in the background without using commanded thruster firings to excite spacecraft dynamical motion for observability. The NASA Magnetospheric Multiscale (MMS) mission is used as a test case for the CM estimator. The four MMS spacecraft carry star cameras for accurate attitude and spin rate estimation. The angle between the spacecraft nominal spin axis (for MMS this is the geometric body Z-axis) and the major principal axis of inertia is called the coning angle. The transverse components of the estimated rate provide a direct measure of the coning angle. The coning angle has been seen to shift slightly after every orbit and attitude maneuver. This change is attributed to a small asymmetry in the fuel distribution that changes with each burn. This paper shows a correlation between the apparent mass asymmetry deduced from the variations in the coning angle and the CM estimates made using the GPS Doppler data. The consistency between the changes in the coning angle and the CM provides validation of the proposed GPS Doppler method for estimation of the CM on spinning spacecraft.

  8. Ultra-tight GPS/IMU Integration based Long-Range Rocket Projectile Navigation

    Handong Zhao

    2016-01-01

    Full Text Available Accurate navigation is important for long-range rocket projectile’s precise striking. For getting a stable and high-performance navigation result, a ultra-tight global position system (GPS, inertial measuring unit integration (IMU-based navigation approach is proposed. In this study, high-accuracy position information output from IMU in a short time to assist the carrier phase tracking in the GPS receiver, and then fused the output information of IMU and GPS based on federated filter. Meanwhile, introduced the cubature kalman filter as the local filter to replace the unscented kalman filter, and improved it with strong tracking principle, then, improved the federated filter with vector sharing theory. Lastly simulation was carried out based on the real ballistic data, from the estimation error statistic figure. The navigation accuracy of the proposed method is higher than traditional method.Defence Science Journal, Vol. 66, No. 1, January 2016, pp. 64-70, DOI: http://dx.doi.org/10.14429/dsj.66.8326

  9. Appending High-Resolution Elevation Data to GPS Speed Traces for Vehicle Energy Modeling and Simulation

    Wood, E.; Burton, E.; Duran, A.; Gonder, J.

    2014-06-01

    Accurate and reliable global positioning system (GPS)-based vehicle use data are highly valuable for many transportation, analysis, and automotive considerations. Model-based design, real-world fuel economy analysis, and the growing field of autonomous and connected technologies (including predictive powertrain control and self-driving cars) all have a vested interest in high-fidelity estimation of powertrain loads and vehicle usage profiles. Unfortunately, road grade can be a difficult property to extract from GPS data with consistency. In this report, we present a methodology for appending high-resolution elevation data to GPS speed traces via a static digital elevation model. Anomalous data points in the digital elevation model are addressed during a filtration/smoothing routine, resulting in an elevation profile that can be used to calculate road grade. This process is evaluated against a large, commercially available height/slope dataset from the Navteq/Nokia/HERE Advanced Driver Assistance Systems product. Results will show good agreement with the Advanced Driver Assistance Systems data in the ability to estimate road grade between any two consecutive points in the contiguous United States.

  10. Great Circle Distance Methode for Improving Operational Control System Based on GPS Tracking System

    Benny Dwi Kifana

    2012-04-01

    Full Text Available Fleet monitoring conducted to determine the position of the movement of the fleet to a point of reference. There are three applications that are necessary for the implementation of the monitoring system. They are Global Positioning System (GPS, Geographic Information System (GIS and Global System for Mobile Communications (GSM technologies. The Great Circle Distance method with two equations, Vincenty and Haversine, is used to calculate the accurate positioning. The experiment results show that the use of the equation Vincenty have better performance in comparison to Haversine equationon overspeeding detection. Accuracy of monitoring is increasing as evidenced by increased frequency of position reporting.

  11. On-board identification of tyre cornering stiffness using dual Kalman filter and GPS

    Lee, Seungyong; Nakano, Kimihiko; Ohori, Masanori

    2015-04-01

    Cornering stiffness is one of the important vehicle parameters for steering control of a vehicle. Accurate vehicle parameters are essential for a high performance of vehicle control because vehicle control is significantly affected by variations in vehicle parameters. In this study, a novel identification method is proposed using a dual Kalman filter algorithm and a GPS (global positioning system) measurement system to estimate the cornering stiffness for on-board identification. Performance of the identification method is examined with experiments, and the estimation results show that this identification method is effective on both a flat road and a banked curve road.

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

    Truong, S. H.

    1999-01-01

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

  13. Where have all the GPs gone – where will they go? Study of Finnish GPs

    Sumanen Markku

    2012-12-01

    Full Text Available Abstract Background In this paper a specialist in general practice is referred to as a general practitioner (GP. In Finland only half of all GPs work as a health centre physician. The present aim was to establish what the working places of specializing and specialized physicians in general practice are, and where they assume they will work in the future. Methods The study population comprised 5,357 physicians licensed in Finland during the years 1977–1996. Altogether 2,956 questionnaires were returned, a response rate of 55.2%. Those either specializing (GP trainees, n=133 or already having specialized (GPs, n=426 in general practice were included in the study. Respondents were asked what kind of physician’s work they would most preferably do. They were further asked what work they assumed they would be doing in the year 2020. Results Altogether 72% were working in public primary health centres and 14% in the private sector. Of GPs 53% and of GP trainees 70% would most preferably work in health centres. Of GPs 14% would most preferably work as private practitioners and 9% as occupational health physicians. Sixteen per cent assumed they would be working as private practitioners and 35% assumed they would be retired in the year 2020. Of GP trainees 57% assumed they would be working as health centre physicians in 2020. Conclusions According to the present findings many experienced GPs will leave their work as a health centre physician. Moreover, several GP trainees do not consider health centre physician’s work as a long-term career option. These trends may in the future reflect a recruiting problem in many primary health centres.

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

    Wang Gao

    2015-10-01

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

  15. Horizontal velocities in the central and eastern United States from GPS surveys during the 1987-1996 interval

    The National Geodetic Survey and the Nuclear Regulatory Commission jointly organized GPS surveys in 1987, 1990, 1993, and 1996 to search for crustal deformation in the central and eastern United States (east of longitude 108 degrees W). We have analyzed the data of these four surveys in combination with VLBI data observed during the 1979-1995 interval and GPS data for 22 additional surveys observed during the 1990-1996 interval. These latter GPS surveys served to establish accurately positioned geodetic marks in various states. Accordingly, we have computed horizontal velocities for 64 GPS sites and 12 VLBI sites relative to a reference frame for which the interior of the North American plate is considered fixed on average. None of our derived velocities exceeds 6 mm/yr in magnitude. Moreover, the derived velocity at each GPS site is statistically zero at the 95% confidence level except for the site BOLTON in central Ohio and the site BEARTOWN in southeastern Pennsylvania. However, as statistical theory would allow approximately 5% of the 64 GPS sites to fall our zero-velocity hypothesis, we are uncertain whether or not these estimated velocities for BOLTON and BEARTOWN reflect actual motion relative to the North American plate. We also computed horizontal strain rates for the cells formed by a 1 degrees by 1 degrees grid spanning the central and eastern United States. Corresponding shearing rates are everywhere less than 60 nanoradians/yr in magnitude, and no shearing rate differs statistically from zero at the 95% confidence level except for a grid cell near BEARTOWN whose rate is 57 ± 26 nanoradians/yr. Also corresponding areal dilatation rates are everywhere less than 40 nanostrain/yr in magnitude, and no dilatation rate differs statistically from zero at the 95% confidence level

  16. Landslide monitoring using Geocubes, a wireless network of low-cost GPS receivers

    Benoit, Lionel; Thom, Christian; Martin, Olivier

    2013-04-01

    Many geophysical structures such as landslides, glaciers or even volcanoes are features characterized by small extend area and deformation rate in the order of 1 to 10cm per day. Their study needs ever more accurate positioning data with an increased space and time resolution. Using an ublox LEA-6T GPS receiver, the French national mapping agency IGN developed its own wireless multi-sensor geo-monitoring system named Geocube. The basic device is equipped with a GPS and a wireless communication media and can be completed with various sensor modules such as meteorological sensors, ground humidity and pressure or seismograph. Due to the low cost of each receiver, spatial dense surveying networks are deployed. Data are then continuously collected and transmitted to a processing computer in real-time as well as saved in situ on a Micro-SD card. Among them, raw GPS carrier phase data give access to real-time accurate relative positioning on all mesh nodes if small baselines are used. In order to achieve a high accuracy, a dedicated GPS data processing method based on a Kalman filter is proposed. It allows an epoch by epoch positioning providing a high time resolution. Special attention is paid on two points : adaptation to wireless networks of low-cost GPS and real-time ability. A first test of Geocubes usability under field conditions was carried out during summer 2012. A fifteen receivers network was deployed on the landslide of Super-Sauze (French Alps) for a two months trial. The experimental area, the deployed network and the acquisition protocol are presented. Position time series with a 30 seconds sampling rate are then derived from raw data for 10 mobile receivers on a forty days session. A sub-centimetric accuracy on an epoch by epoch positioning is reached despite difficult field conditions due to a 40° elevation mask in the south direction. Then, the measured deformations are compared with in situ rainfall measurements collected by a dedicated sensor added to

  17. Differential GPS and system integration of the Low Visibility Landing and Surface Operations (LVLASO) demonstration

    Rankin, James M.

    1994-01-01

    The LVLASO Flight Demonstration of ASTA concepts (FDAC) integrates NASA-Langley's electronic moving map display and Transport Systems Research Vehicle (TSRV) (a modified Boeing 737 aircraft); ARINC's VHF data link, GPS ground station, and automated controller workstation; and Norden's surface radar/airport movement safety system. Aircraft location is shown on the electronic map display in the cockpit. An approved taxi route as well as other aircraft and surface traffic are also displayed. An Ashtech Z12 Global Positioning System (GPS) receiver on the TSRV estimates the aircraft's position. In Differential mode (DSPS), the Ashtech receiver accepts differential C/A code pseudorange corrections from a GPS ground station. The GPS ground station provides corrections up to ten satellites. The corrections are transmitted on a VHF data link at a 1 Hz. rate using the RTCM-104 format. DGPS position estimates will be within 5 meters of actual aircraft position. DGPS position estimates are blended with position, velocity, acceleration, and heading data from the TSRV Air Data/Inertial Reference System (ADIRS). The ADIRS data is accurate in the short-term, but drifts over time. The DGPS data is used to keep the ADIRS position accurate. Ownship position, velocity, heading, and turn rate are sent at a 20 Hz. rate to the electronic map display. Airport traffic is detected by the airport surface radar system. Aircraft and vehicles such as fuel trucks and baggage carts are detected. The traffic's location, velocity, and heading are sent to the TSRV. To prevent traffic symbology from jumping each second when a location update arrives, velocity and heading are used to predict a new traffic location for each display update. Possible runway incursions and collisions can be shown on the electronic map. Integrating the different systems used in the FDAC requires attention to the underlying coordinate systems. The airport diagram displayed on the electronic map is obtained from published

  18. Ionospheric error analysis in gps measurements

    G. Pugliano

    2008-06-01

    Full Text Available The results of an experiment aimed at evaluating the effects of the ionosphere on GPS positioning applications are presented in this paper. Specifically, the study, based upon a differential approach, was conducted utilizing GPS measurements acquired by various receivers located at increasing inter-distances. The experimental research was developed upon the basis of two groups of baselines: the first group is comprised of "short" baselines (less than 10 km; the second group is characterized by greater distances (up to 90 km. The obtained results were compared either upon the basis of the geometric characteristics, for six different baseline lengths, using 24 hours of data, or upon temporal variations, by examining two periods of varying intensity in ionospheric activity respectively coinciding with the maximum of the 23 solar cycle and in conditions of low ionospheric activity. The analysis revealed variations in terms of inter-distance as well as different performances primarily owing to temporal modifications in the state of the ionosphere.

  19. TAGGING, TRACKING AND LOCATING WITHOUT GPS

    Cordaro, J.; Coleman, T.; Shull, D.

    2012-07-08

    The Savannah River National Laboratory (SRNL) was requested to lead a Law Enforcement Working Group that was formed to collaborate on common operational needs. All agencies represented on the working group ranked their need to tag, track, and locate a witting or unwitting target as their highest priority. Specifically, they were looking for technologies more robust than Global Positioning Satellite (GPS), could communicate back to the owner, and worked where normal cell phone communications did not work or were unreliable. SRNL brought together multiple technologies in a demonstration that was held in in various Alaska venues, including metropolitan, wilderness, and at-sea that met the working group's requirements. Using prototypical technologies from Boeing, On Ramp, and Fortress, SRNL was able to demonstrate the ability to track personnel and material in all scenarios including indoors, in heavily wooden areas, canyons, and in parking garages. In all cases GPS signals were too weak to measure. Bi-directional communication was achieved in areas that Wi-Fi, cell towers, or traditional radios would not perform. The results of the exercise will be presented. These technologies are considered ideal for tracking high value material such has nuclear material with a platform that allows seamless tracking anywhere in the world, indoors or outdoors.

  20. Automatic Campus Network Management using GPS

    Jayakumar.S

    2012-05-01

    Full Text Available The Organization Network is the place where large number of attacks is happening. The attackers are using different methodologies to capture the information from the end user without the knowledge of the end-user. This paper introduces the concepts of Campus Management and Emergency log by using Medium Access Control (MAC and Global Positioning System (GPS. By using the IP address of an attacker, the MAC address can be found and the attackers machine can be blocked access with the help of firewall. Using the GPS we can be able to navigate the attackers position with the help of the position log. The log keeps updating for each and every 10 seconds. The attacker can be identified as if he used his own system or victim (3rd party system. An emergency response log has been created to record each emergency incident response process. The role of the log is more important with an increasing accumulation of information with the log; Network Engineer/Administrator can determine the type of inevitable emergency incidents grouped into evitable events, in order to improve the system reliability of emergency response.

  1. Accurate Vehicle Location System Using RFID, an Internet of Things Approach.

    Prinsloo, Jaco; Malekian, Reza

    2016-01-01

    Modern infrastructure, such as dense urban areas and underground tunnels, can effectively block all GPS signals, which implies that effective position triangulation will not be achieved. The main problem that is addressed in this project is the design and implementation of an accurate vehicle location system using radio-frequency identification (RFID) technology in combination with GPS and the Global system for Mobile communication (GSM) technology, in order to provide a solution to the limitation discussed above. In essence, autonomous vehicle tracking will be facilitated with the use of RFID technology where GPS signals are non-existent. The design of the system and the results are reflected in this paper. An extensive literature study was done on the field known as the Internet of Things, as well as various topics that covered the integration of independent technology in order to address a specific challenge. The proposed system is then designed and implemented. An RFID transponder was successfully designed and a read range of approximately 31 cm was obtained in the low frequency communication range (125 kHz to 134 kHz). The proposed system was designed, implemented, and field tested and it was found that a vehicle could be accurately located and tracked. It is also found that the antenna size of both the RFID reader unit and RFID transponder plays a critical role in the maximum communication range that can be achieved. PMID:27271638

  2. Accurate Vehicle Location System Using RFID, an Internet of Things Approach

    Jaco Prinsloo

    2016-06-01

    Full Text Available Modern infrastructure, such as dense urban areas and underground tunnels, can effectively block all GPS signals, which implies that effective position triangulation will not be achieved. The main problem that is addressed in this project is the design and implementation of an accurate vehicle location system using radio-frequency identification (RFID technology in combination with GPS and the Global system for Mobile communication (GSM technology, in order to provide a solution to the limitation discussed above. In essence, autonomous vehicle tracking will be facilitated with the use of RFID technology where GPS signals are non-existent. The design of the system and the results are reflected in this paper. An extensive literature study was done on the field known as the Internet of Things, as well as various topics that covered the integration of independent technology in order to address a specific challenge. The proposed system is then designed and implemented. An RFID transponder was successfully designed and a read range of approximately 31 cm was obtained in the low frequency communication range (125 kHz to 134 kHz. The proposed system was designed, implemented, and field tested and it was found that a vehicle could be accurately located and tracked. It is also found that the antenna size of both the RFID reader unit and RFID transponder plays a critical role in the maximum communication range that can be achieved.

  3. Accurate Vehicle Location System Using RFID, an Internet of Things Approach

    Prinsloo, Jaco; Malekian, Reza

    2016-01-01

    Modern infrastructure, such as dense urban areas and underground tunnels, can effectively block all GPS signals, which implies that effective position triangulation will not be achieved. The main problem that is addressed in this project is the design and implementation of an accurate vehicle location system using radio-frequency identification (RFID) technology in combination with GPS and the Global system for Mobile communication (GSM) technology, in order to provide a solution to the limitation discussed above. In essence, autonomous vehicle tracking will be facilitated with the use of RFID technology where GPS signals are non-existent. The design of the system and the results are reflected in this paper. An extensive literature study was done on the field known as the Internet of Things, as well as various topics that covered the integration of independent technology in order to address a specific challenge. The proposed system is then designed and implemented. An RFID transponder was successfully designed and a read range of approximately 31 cm was obtained in the low frequency communication range (125 kHz to 134 kHz). The proposed system was designed, implemented, and field tested and it was found that a vehicle could be accurately located and tracked. It is also found that the antenna size of both the RFID reader unit and RFID transponder plays a critical role in the maximum communication range that can be achieved. PMID:27271638

  4. Robust GPS carrier tracking under ionospheric scintillation

    Susi, M.; Andreotti, M.; Aquino, M. H.; Dodson, A.

    2013-12-01

    Small scale irregularities present in the ionosphere can induce fast and unpredictable fluctuations of Radio Frequency (RF) signal phase and amplitude. This phenomenon, known as scintillation, can degrade the performance of a GPS receiver leading to cycle slips, increasing the tracking error and also producing a complete loss of lock. In the most severe scenarios, if the tracking of multiple satellites links is prevented, outages in the GPS service can also occur. In order to render a GPS receiver more robust under scintillation, particular attention should be dedicated to the design of the carrier tracking stage, that is the receiver's part most sensitive to these types of phenomenon. This paper exploits the reconfigurability and flexibility of a GPS software receiver to develop a tracking algorithm that is more robust under ionospheric scintillation. For this purpose, first of all, the scintillation level is monitored in real time. Indeed the carrier phase and the post correlation terms obtained by the PLL (Phase Locked Loop) are used to estimate phi60 and S4 [1], the scintillation indices traditionally used to quantify the level of phase and amplitude scintillations, as well as p and T, the spectral parameters of the fluctuations PSD. The effectiveness of the scintillation parameter computation is confirmed by comparing the values obtained by the software receiver and the ones provided by a commercial scintillation monitoring, i.e. the Septentrio PolarxS receiver [2]. Then the above scintillation parameters and the signal carrier to noise density are exploited to tune the carrier tracking algorithm. In case of very weak signals the FLL (Frequency Locked Loop) scheme is selected in order to maintain the signal lock. Otherwise an adaptive bandwidth Phase Locked Loop (PLL) scheme is adopted. The optimum bandwidth for the specific scintillation scenario is evaluated in real time by exploiting the Conker formula [1] for the tracking jitter estimation. The performance

  5. INVESTIGATION OF TIGHTLY COUPLED SINS/GPS INTEGRATION MIDCOURSE GUIDANCE FOR AIR-TO-AIR MISSILES

    1998-01-01

    The applied problems of SINS/GPS integration navigation system existing in midcourse guidance of air-to-air missiles have been investigated recently. In comparison with those investigations existing in current publications, a new tightly coupled SINS/GPS integration navigation system for air-to-air missiles, based on the decorrelated pseudo-range approach, is presented in this paper. Because of high jamming and dynamic of air-to-air missiles, inertial velocity aiding GPS receiver is used to provide a more accurate, jam-resistant measurement for midcourse guidance systems. A tracking error estimator is designed to distinguish the correlation that existed between pseudo-range measurements and inertial information. It is found better to regard inertial velocity aiding errors as the noise of which statistical properties are unknown. So using mixed Kalman/minimax filtering theory, one can obtain the new tracking error estimator with simple and robust algorithm through constructing a composite filter consisting of two parts: Kalman filter for the noise of known statistics and minimax filter for the unknown. In order to ensure this simple estimator stability, a new method is proposed to choose its parameters, based on Khargonekars work. Moreover, it is demonstrated that the given method also ensures the proposed estimator optimality. All the work mentioned above is involved in the tightly coupled SINS/GPS integration midcourse system design in which a set of low-accuracy inertial components is shared by SINS and autopilot. Simulation results of a certain type of air-to-air missile are presented. Due to decorrelation by the tracking error estimator, only small white noise of pseudo-range measurements remains. So it is shown that application of the new midcourse guidance system results in better guidance accuracy, higher jam-resistance.

  6. RTK-GPS positioning by TV audio-MPX-data broadcast in Japan

    Namie, Hiromune; Yasuda, Akio; Sasano, Koji

    2000-10-01

    RTK-GPS is a satellite positioning system which provides instant and accurate positions. The ranging error to the satellite from a user GPS antenna determined by the phase measurement of the carrier waves from the GPS satellites is of the order of mms. Thus an accuracy of a few cm can be easily obtained. The system is easier to operate than a traditional survey system such as the `Total Station'. Hence it has been used for many applications in Japan. It is necessary, however, to provide a fast data communication link for the transmission of carrier phase data from a reference station located at a known position, to a user receiver. A radio communication device with low power, is commonly used because it requires no license. However the data transmission area is generally limited to just several hundred meters in radius from the reference station. The authors have investigated RTK-GPS positioning with several different lengths of baseline using data transmission via TV audio-MPX-data broadcast, and evaluated its validity. The carrier phase data is transmitted from the reference receiver at the Tokyo University of Mercantile Marine, to the experimental station of the Asahi National Broadcasting Company, by public phone line with data rate 9,600 bps. The data, which when multiplexed into TV audio, was then disseminated with the rate of about 8 kbps from the Tokyo Tower. The data transmission delay in this system appeared random between 0.740 and 1.317 s, of which the difference (0.577 s) corresponds to the transmission time of 32 blocks of multiplexed data. Positioning was tried at several fixed points with different lengths of baseline (0-21 km). Tests proved that the accuracy became worse as the length of baselines became longer. The 2drms height are less than the 2.5 cm, and `Fix' solution success rates are more than 98%, for shorter baselines less than 10 km in length.

  7. Taking correlations in GPS least squares adjustments into account with a diagonal covariance matrix

    Kermarrec, Gaël; Schön, Steffen

    2016-05-01

    -dependent diagonal covariance matrix is appropriate to take correlations in GPS least squares adjustment into account, yielding more accurate cofactor matrices of the unknown.

  8. The impact of data assimilation of ground-based GPS precipitable water vapor to numerical weather prediction model on estimation of ray-traced atmospheric slant delays

    Ichikawa, R.; Hobiger, T.; Shoji, Y.; Miyauchi, Y.

    2012-12-01

    The ''KAshima RAytracing Tools (KARAT)'' is capable of calculating total slant delays and ray-bending angles considering real atmospheric phenomena. One advantage of KARAT is that the reduction of atmospheric path delay will become more accurate each time the numerical weather model is improved. On October 27, 2009 the JMA started data assimilation of zenith wet delays obtained by the GPS Earth Observation Network System (GEONET) operated by Geospatial Information Authority of Japan (GSI) for meso-scale NWP model. The improved NWP model data assimilating the GPS PWV data has the potential to correct the atmospheric path delay more precisely. Meteorological Research Institute (MRI) of Japan has evaluated the impact of ground-based GPS precipitable water vapor (GPS PWV) derived from the GEONET on meso-scale NWP model under the localized heavy rainfall event in Tokyo, Japan on 5 August 2008. A terrific thunderstorm occurred across the Kanto area of Japan, and it caused flooding in downtown Tokyo. During the event, the rainfall intensity increased to over 100 mm per hour within thirty minutes. We have assessed the impacts of GPS PWV assimilation into the NWP model on the KARAT correction by comparisons of the precise point positioning (PPP) solutions. In the nationwide scale of Japan, the short time repeatability of the PPP results for both horizontal and height positions applying KARAT correction through the MRI NWP model with GPS PWV assimilation are about several percent better than that through the conventional MRI NPW model w/o GPS PWV assimilation. In addition we are now investigating the impact of GPS PWV data assimilation in more detail. We will present the updated results of the comparison study.

  9. Modeling low elevation GPS signal propagation in maritime atmospheric ducts

    Zhang, Jinpeng; Wu, Zhensen; Wang, Bo; Wang, Hongguang; Zhu, Qinglin

    2012-05-01

    Using the parabolic wave equation (PWE) method, we model low elevation GPS L1 signal propagation in maritime atmospheric ducts. To consider sea surface impedance, roughness, and the effects of earth's curvature, we propose a new initial field model for the GPS PWE split-step solution. On the basis of the comparison between the proposed model and the conventional initial field model for a smooth, perfectly conducting sea surface on a planar earth, we conclude that both the amplitude and phase of the initial field are influenced by surface impedance and roughness, and that the interference behavior between direct and reflected GPS rays is affected by earth's curvature. The performance of the proposed model is illustrated with examples of low elevation GPS L1 signal propagation in three types of ducts: an evaporation duct, a surface-based duct, and an elevated duct. The GPS PWE is numerically implemented using the split-step discrete mixed Fourier transform algorithm to enforce impedance-type boundary conditions at the rough sea surface. Because the GPS signal is right hand circularly polarized, we calculate its power strength by combining the propagation predictions of the horizontally and the vertically polarized components. The effects of the maritime atmospheric ducts on low elevation GPS signal propagation are demonstrated according to the presented examples, and the potential applications of the GPS signals affected by ducts are discussed.

  10. Crustal deformations at permanent GPS sites in Denmark

    Khan, Shfaqat Abbas; Knudsen, Per; Tscherning, Carl Christian

    2005-01-01

    The National Survey and Cadastre (KMS) is responsible for the geodetic definition of the reference network in Denmark. Permanent GPS stations play an important role in the monitoring and maintenance of the geodetic network. During 1998 and 1999 KMS established three permanent GPS station in Denma...

  11. Backyard Botany: Using GPS Technology in the Science Classroom

    March, Kathryn A.

    2012-01-01

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

  12. Empathy: what does it mean for GPs? A qualitative study

    Derksen, F.; Bensing, J.; Kuiper, S.; Meerendonk, M. van; Lagro-Janssen, A.

    2015-01-01

    BACKGROUND: Research has highlighted empathy as an important and effective factor in patient-physician communication. GPs have extensive practical experience with empathy. However, little is known about the personal views of GPs regarding the meaning and application of empathy in daily practice. OBJ

  13. PDOP values for simulated GPS/Galileo positioning

    Cederholm, Jens Peter

    2005-01-01

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

  14. ATTITUDE RATE ESTIMATION BY GPS DOPPLER SIGNAL PROCESSING

    He Side; Milos Doroslovacki; Guo Zhenyu; Zhang Yufeng

    2003-01-01

    A method is presented for near-Earth spacecraft or aviation vehicle's attitude rate estimation by using relative Doppler frequency shift of the Global Positioning System (GPS)carrier. It comprises two GPS receiving antennas, a signal processing circuit and an algorithm.The whole system is relatively simple, the cost and wcight, as well as power consumption, are very low.

  15. Crustal deformations at permanent GPS sites in Denmark

    Khan, Shfaqat Abbas; Knudsen, Per; Tscherning, Carl Christian

    The National Survey and Cadastre (KMS) is responsible for the geodetic definition of the reference network in Denmark. Permanent GPS stations play an important role in the monitoring and maintenance of the geodetic network. During 1998 and 1999 KMS established three permanent GPS station in Denma...

  16. A Design of GPS Embedded in Nuclear Instruments

    This paper introduces the design of GPS system which is embedded in nuclear instruments. By using the LEA-4H which combines a small GPS module with high sensitivity and low power consumption, we can conveniently get the measuring point position information from our instruments for easy analysis. (authors)

  17. Two laboratory methods for the calibration of GPS speed meters

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

  18. The handhold GPS in the coordinate conversion in of application

    The Handhold GPS whether in geological mapping, or in drilling layout, which has showed the simple and practical side, and it is convenient and quick in the coordinate conversion. This article introduced in the condition of the higher accuracy coordinate conversion parameters, with the superiority of using handhold GPS for the Gauss projection coordinate conversion. (author)

  19. Coordinate Time and Proper Time in the GPS

    Matolcsi, T.; Matolcsi, M.

    2008-01-01

    The global positioning system (GPS) provides an excellent educational example of how the theory of general relativity is put into practice and becomes part of our everyday life. This paper gives a short and instructive derivation of an important formula used in the GPS, and is aimed at graduate students and general physicists. The authors…

  20. GPS kinematic field in Central and Northern Italy

    Cenni, Nicola; Baldi, Paolo; Mantovani, Enzo; Viti, Marcello; Babbucci, Daniele

    2013-04-01

    The GPS observation of more than 350 continuous GPS stations located in the Central and Northern Italian peninsula have been analyzed in order to reconstruct the present kinematic pattern in the area. Several sites (about 100) are managed by public companies and scientific research institutions aimed at performing accurate monitoring of earth surface movements, other sites are managed by public institutions and private agencies to support mapping activities, rescue and emergency services and real-time positioning (VRS and RTK).We have processed with GAMIT software all the available data for the period 2001-2012. The network is divided into 21 sub-networks, each including at least the six common stations. The IGS precise ephemerides have been included in the processing with tight constraints, such as the Earth Orientation Parameter (EOP). The daily loosely constrained solutions of the 21 clusters have been combined into a unique solution by the GLOBK software. Such solution has been then aligned into the ITRF2008 reference frame by a weighted six parameters transformation (three translation and three rotation), using the ITRF2008 coordinates and velocities of the five high quality common IGS stations (CAGL, GRAZ, MATE, WTZR and ZIMM). The sites with an observation time span less than two years have been excluded from the analysis of kinematic pattern, because it is hard to get a robust estimate of rate, seasonal signals and steps with less than two years of observation. The horizontal kinematic pattern has been analyzed in order to gain information about the present short term deformation pattern of this region. This analysis may have significant implications for the recognition of seismic zones most prone to next strong earthquakes. The vertical velocity field has been also considered in this study. It is largely recognized that vertical movements in the Central - Northern Italy may be considered as the overall result of three main causes: tectonic processes

  1. Do French low-income GPs choose to work less?

    Samson, Anne-Laure

    2011-09-01

    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 activity in response to a negative demand shock, it appears that their low-income status is attributable to a strong preference for leisure. PMID:21728212

  2. Estimering af brændstofforbrug vha. GPS Data

    Andersen, Ove; Lahrmann, Harry; Torp, Kristian

    2010-01-01

    Det er simpelt og billigt at opsamle GPS målinger fra køretøjer. Når større mængder GPS data indsamles fra et passende antal køretøjer kan dataen bruges til at beregne f.eks. køretider. Det er ligeledes muligt ud fra GPS data at estimere miljøindikatorer så som, hvor aggressivt kører bilister og er...... der nogle vejstrækninger, der har en højere (negativ) miljø påvirkning end andre? I denne artikel præsenterer et forsøg, hvor GPS data anvendes til at estimere brændstofforbruget ved en enkelt tur og for vejnettet generelt. Dette gøres ved at opbygge en database med GPS data. Ud fra disse data gives...

  3. Preconditions to ground based GPS water vapour tomography

    M. Bender

    2007-08-01

    Full Text Available The GPS water vapour tomography is a new technique which provides spatially resolved water vapour distributions in the atmosphere under all weather conditions. This work investigates the information contained in a given set of GPS signals as a precondition to an optimal tomographic reconstruction. The spatial distribution of the geometric intersection points between different ray paths is used to estimate the information density. Different distributions of intersection points obtained from hypothetical GPS networks with varying densities of GPS stations are compared with respect to the horizontal and vertical resolution of a subsequent tomographic reconstruction. As a result some minimum requirements for continuously operating extensive GPS networks for meteorological applications are given.

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

    S. Rudenko

    2012-07-01

    Full Text Available 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 of typical behavior of station height changes are given and interpreted. The derived time series and vertical motions of continuous GPS at tide gauges stations can be used for correcting tide gauge estimates of regional and global sea level changes.

  5. Accurate Geodetic Coordinates for Observatories on Cerro Tololo and Cerro Pachon

    Mamajek, Eric E

    2012-01-01

    As the 50th anniversary of the Cerro Tololo Inter-American Observatory (CTIO) draws near, the author was surprised to learn that the published latitude and longitude for CTIO in the Astronomical Almanac and iraf observatory database appears to differ from modern GPS-measured geodetic positions by nearly a kilometer. Surely, the position for CTIO could not be in error after five decades? The source of the discrepancy appears to be due to the ~30" difference between the astronomical and geodetic positions -- a systematic effect due to vertical deflection first reported by Harrington, Mintz Blanco, & Blanco (1972). Since the astronomical position is not necessarily the desired quantity for some calculations, and since the number of facilities on Cerro Tololo and neighboring Cerro Pachon has grown considerably over the years, I decided to measure accurate geodetic positions for all of the observatories and some select landmarks on the two peaks using GPS and Google Earth. Both sets of measurements were inter-...

  6. GPS SYSTEMS LITERATURE: INACCURACY FACTORS AND EFFECTIVE SOLUTIONS

    Li Nyen Thin

    2016-03-01

    Full Text Available Today, Global Positioning System (GPS is widely used in almost every aspect of our daily life. Commonly, users utilize the technology to track the position of a vehicle or an object of interest. They also use it to safely navigate to the destination of their choice. As a result, there are countless number of GPS based tracking application that has been developed. But, a main recurring issue that exists among these applications are the inaccuracy of the tracking faced by users and this issue has become a rising concern. Most existing research have examined the effects that the inaccuracy of GPS have on users while others identified suitable methods to improve the accuracy of GPS based on one or two factors. The objective of this survey paper is to identify the common factors that affects the accuracy of GPS and identify an effective method which could mitigate or overcome most of those factors. As part of our research, we conducted a thorough examination of the existing factors for GPS inaccuracies. According to an initial survey that we have collected, most of the respondents has faced some form of GPS inaccuracy. Among the common issues faced are inaccurate object tracking and disconnection of GPS signal while using an application. As such, most of the respondents agree that it is necessary to improve the accuracy of GPS. This leads to another objective of this paper, which is to examine and evaluate existing methods as well as to identify the most effective method that could improve the accuracy of GPS.

  7. Analysis of GPS Abnormal Conditions within Fault Tolerant Control Laws

    Al-Sinbol, Gahssan

    The Global Position System (GPS) is a critical element for the functionality of autonomous flying vehicles. The GPS operation at normal and abnormal conditions directly impacts the trajectory tracking performance of the autonomous Unmanned Aerial Vehicles (UAVs) controllers. The effects of GPS parameter variation must be well understood and user-friendly computational tools must be developed to facilitate the design and evaluation of fault tolerant control laws. This thesis presents the development of a simplified GPS error model in Matlab/Simulink and its use performing a sensitivity analysis of GPS parameters effect under system normal and abnormal operation on different UAV trajectory tracking controllers. The model statistically generates position and velocity errors, simulates the effect of GPS satellite configuration on the position and velocity measurement accuracy, and implements a set of failures to the GPS readings. The model and its graphical user interface was integrated within the WVU UAV simulation environment as a masked Simulink block. The effects on the controllers' trajectory tracking performance of the following GPS parameters were investigated within normal operation ranges and outside: time delay, update rate, error standard deviation, bias, and major position and velocity failures. Several sets of control laws with fixed and adaptive parameters and of different levels of complexity have been used in this investigation. A complex performance index formulated in terms of tracking errors and control activity was used for control laws performance evaluation. The composition of various metrics within the performance index was performed using fixed and variable weights depending on the local characteristics of the commanded trajectory. This study has revealed that GPS error parameters have a significant impact on control laws performance. The proposed GPS model has proved to be a valuable, flexible tool for testing and evaluation of the fault

  8. GPS-supported visual SLAM with a rigorous sensor model for a panoramic camera in outdoor environments.

    Shi, Yun; Ji, Shunping; Shi, Zhongchao; Duan, Yulin; Shibasaki, Ryosuke

    2012-01-01

    Accurate localization of moving sensors is essential for many fields, such as robot navigation and urban mapping. In this paper, we present a framework for GPS-supported visual Simultaneous Localization and Mapping with Bundle Adjustment (BA-SLAM) using a rigorous sensor model in a panoramic camera. The rigorous model does not cause system errors, thus representing an improvement over the widely used ideal sensor model. The proposed SLAM does not require additional restrictions, such as loop closing, or additional sensors, such as expensive inertial measurement units. In this paper, the problems of the ideal sensor model for a panoramic camera are analysed, and a rigorous sensor model is established. GPS data are then introduced for global optimization and georeferencing. Using the rigorous sensor model with the geometric observation equations of BA, a GPS-supported BA-SLAM approach that combines ray observations and GPS observations is then established. Finally, our method is applied to a set of vehicle-borne panoramic images captured from a campus environment, and several ground control points (GCP) are used to check the localization accuracy. The results demonstrated that our method can reach an accuracy of several centimetres. PMID:23344377

  9. GPS-Supported Visual SLAM with a Rigorous Sensor Model for a Panoramic Camera in Outdoor Environments

    Ryosuke Shibasaki

    2012-12-01

    Full Text Available Accurate localization of moving sensors is essential for many fields, such as robot navigation and urban mapping. In this paper, we present a framework for GPS-supported visual Simultaneous Localization and Mapping with Bundle Adjustment (BA-SLAM using a rigorous sensor model in a panoramic camera. The rigorous model does not cause system errors, thus representing an improvement over the widely used ideal sensor model. The proposed SLAM does not require additional restrictions, such as loop closing, or additional sensors, such as expensive inertial measurement units. In this paper, the problems of the ideal sensor model for a panoramic camera are analysed, and a rigorous sensor model is established. GPS data are then introduced for global optimization and georeferencing. Using the rigorous sensor model with the geometric observation equations of BA, a GPS-supported BA-SLAM approach that combines ray observations and GPS observations is then established. Finally, our method is applied to a set of vehicle-borne panoramic images captured from a campus environment, and several ground control points (GCP are used to check the localization accuracy. The results demonstrated that our method can reach an accuracy of several centimetres.

  10. GPS Software Packages Deliver Positioning Solutions

    2010-01-01

    "To determine a spacecraft s position, the Jet Propulsion Laboratory (JPL) developed an innovative software program called the GPS (global positioning system)-Inferred Positioning System and Orbit Analysis Simulation Software, abbreviated as GIPSY-OASIS, and also developed Real-Time GIPSY (RTG) for certain time-critical applications. First featured in Spinoff 1999, JPL has released hundreds of licenses for GIPSY and RTG, including to Longmont, Colorado-based DigitalGlobe. Using the technology, DigitalGlobe produces satellite imagery with highly precise latitude and longitude coordinates and then supplies it for uses within defense and intelligence, civil agencies, mapping and analysis, environmental monitoring, oil and gas exploration, infrastructure management, Internet portals, and navigation technology."

  11. CASA Uno GPS orbit and baseline experiments

    Schutz, B. E.; Ho, C. S.; Abusali, P. A. M.; Tapley, B. D.

    1990-01-01

    CASA Uno data from sites distributed in longitude from Australia to Europe have been used to determine orbits of the GPS satellites. The characteristics of the orbits determined from double difference phase have been evaluated through comparisons of two-week solutions with one-week solutions and by comparisons of predicted and estimated orbits. Evidence of unmodeled effects is demonstrated, particularly associated with the orbit planes that experience solar eclipse. The orbit accuracy has been assessed through the repeatability of unconstrained estimated baseline vectors ranging from 245 km to 5400 km. Both the baseline repeatability and the comparison with independent space geodetic methods give results at the level of 1-2 parts in 100,000,000. In addition, the Mojave/Owens Valley (245 km) and Kokee Park/Ft. Davis (5409 km) estimates agree with VLBI and SLR to better than 1 part in 100,000,000.

  12. GPS Imaging of Sierra Nevada Uplift

    Hammond, W. C.; Blewitt, G.; Kreemer, C.

    2015-12-01

    Recent improvements in the scope and precision of GPS networks across California and Nevada have allowed for uplift of the Sierra Nevada to be observed directly. Much of the signal, in the range of 1 to 2 mm/yr, has been attributed to lithospheric scale rebound following massive groundwater withdrawal in the San Joaquin Valley in southern California, exacerbated by drought since 2011. However, natural tectonic deformation associated with long term uplift of the range may also contribute to the observed signal. We have developed new algorithms that enhance the signal of Sierra Nevada uplift and improve our ability to interpret and separate natural tectonic signals from anthropogenic contributions. We apply our new Median Interannual Difference Adjusted for Skewness (MIDAS) algorithm to the vertical times series and a inverse distance-weighted median spatial filtering and Delaunay-based interpolation to despeckle the rate map. The resulting spatially continuous vertical rate field is insensitive to outliers and steps in the GPS time series, and omits isolated features attributable to unstable stations or unrepresentative rates. The resulting vertical rate field for California and Nevada exhibits regionally coherent signals from the earthquake cycle including interseismic strain accumulation in Cascadia, postseismic relaxation of the mantle from recent large earthquakes in central Nevada and southern California, groundwater loading changes, and tectonic uplift of the Sierra Nevada and Coast Ranges. Uplift of the Sierra Nevada extends from the Garlock Fault in the south to an indefinite boundary in the north near the latitude of Mt. Lassen to the eastern Sierra Nevada range front in Owen's Valley. The rates transition to near zero in the southern Walker Lane. The eastern boundary of uplift coincides with the highest strain rates in the western Great Basin, suggesting higher normal fault slip rates and a component of tectonic uplift of the Sierra Nevada.

  13. Validation of ionospheric electron density profiles inferred from GPS occultation observations of the GPS/MET experiment

    Kawakami, Todd Mori

    In April of 1995, the launch of the GPS Meteorology Experiment (GPS/MET) onboard the Orbview-1 satellite, formerly known as Microlab-1, provided the first technology demonstration of active limb sounding of the Earth's atmosphere with a low Earth orbiting spacecraft utilizing the signals transmitted by the satellites of the Global Positioning System (GPS). Though the experiment's primary mission was to probe the troposphere and stratosphere, GPS/MET was also capable of making radio occultation observations of the ionosphere. The application of the GPS occultation technique to the upper atmosphere created a unique opportunity to conduct ionospheric research with an unprecedented global distribution of observations. For operational support requirements, the Abel transform could be employed to invert the horizontal TEC profiles computed from the L1 and L2 phase measurements observed by GPS/MET into electron density profiles versus altitude in near real time. The usefulness of the method depends on how effectively the TEC limb profiles can be transformed into vertical electron density profiles. An assessment of GPS/MET's ability to determine electron density profiles needs to be examined to validate the significance of the GPS occultation method as a new and complementary ionospheric research tool to enhance the observational databases and improve space weather modeling and forecasting. To that end, simulations of the occultation observations and their inversions have been conducted to test the Abel transform algorithm and to provide qualitative information about the type and range of errors that might be experienced during the processing of real data. Comparisons of the electron density profiles inferred from real GPS/MET observations are then compared with coincident in situ measurements from the satellites of Defense Meteorological Satellite Program (DMSP) and ground-based remote sensing from digisonde and incoherent scatter radar facilities. The principal focus of

  14. Accurate ab initio spin densities

    Boguslawski, Katharina; Legeza, Örs; Reiher, Markus

    2012-01-01

    We present an approach for the calculation of spin density distributions for molecules that require very large active spaces for a qualitatively correct description of their electronic structure. Our approach is based on the density-matrix renormalization group (DMRG) algorithm to calculate the spin density matrix elements as basic quantity for the spatially resolved spin density distribution. The spin density matrix elements are directly determined from the second-quantized elementary operators optimized by the DMRG algorithm. As an analytic convergence criterion for the spin density distribution, we employ our recently developed sampling-reconstruction scheme [J. Chem. Phys. 2011, 134, 224101] to build an accurate complete-active-space configuration-interaction (CASCI) wave function from the optimized matrix product states. The spin density matrix elements can then also be determined as an expectation value employing the reconstructed wave function expansion. Furthermore, the explicit reconstruction of a CA...

  15. Accurate Modeling of Advanced Reflectarrays

    Zhou, Min

    of the incident field, the choice of basis functions, and the technique to calculate the far-field. Based on accurate reference measurements of two offset reflectarrays carried out at the DTU-ESA Spherical NearField Antenna Test Facility, it was concluded that the three latter factors are particularly important...... to the conventional phase-only optimization technique (POT), the geometrical parameters of the array elements are directly optimized to fulfill the far-field requirements, thus maintaining a direct relation between optimization goals and optimization variables. As a result, better designs can be obtained compared...... using the GDOT to demonstrate its capabilities. To verify the accuracy of the GDOT, two offset contoured beam reflectarrays that radiate a high-gain beam on a European coverage have been designed and manufactured, and subsequently measured at the DTU-ESA Spherical Near-Field Antenna Test Facility...

  16. Inertial Aided Kinematic GPS Cycle Slip Detection and Correction for GPS/INS Tightly Coupled System

    HAN Houzeng

    2015-08-01

    Full Text Available In order to improve the navigation performance and robustness, a GPS/INS tightly coupled model has been developed, the INS related bias and ionospheric errors were compensated and corrected, the impact of combination observations on cycle slip detection was investigated, and four combinations with the characteristics of longer wavelength, smaller noise and lower ionosphere effect were determined, then an innovative inertial aided adaptive cycle slip detection and correction algorithm based on the selected combination observations was presented, and the impact of INS positioning errors on cycle slip detection has been investigated, the probability of false alarm and success rate of cycle slip correction were utilized to enhance the integrity of cycle slip detection and correction, a new threshold determination criterion was provided to achieve robust cycle slip detection and correction. At last, a field test was utilized to verify and evaluate the performance of the proposed algorithm, multi-cycle slips and GPS gap scenarios were simulated, the results show that the scheme works effectively as long as the complete GPS data outage period is less than 20 second, the performance degrades as the outage period becomes longer; while during the partial data outage durations, the proposed scheme can fix the cycle slips correctly for the simulated 90 second partial outage due to the improved positioning accuracy, a total of 170 dense cycle slips (1 slip per 5 epochswere introduced, it shows that all introduced cycle slips are successfully detected and the true fixing rate reaches 99.41%.

  17. Accurate thickness measurement of graphene

    Shearer, Cameron J.; Slattery, Ashley D.; Stapleton, Andrew J.; Shapter, Joseph G.; Gibson, Christopher T.

    2016-03-01

    Graphene has emerged as a material with a vast variety of applications. The electronic, optical and mechanical properties of graphene are strongly influenced by the number of layers present in a sample. As a result, the dimensional characterization of graphene films is crucial, especially with the continued development of new synthesis methods and applications. A number of techniques exist to determine the thickness of graphene films including optical contrast, Raman scattering and scanning probe microscopy techniques. Atomic force microscopy (AFM), in particular, is used extensively since it provides three-dimensional images that enable the measurement of the lateral dimensions of graphene films as well as the thickness, and by extension the number of layers present. However, in the literature AFM has proven to be inaccurate with a wide range of measured values for single layer graphene thickness reported (between 0.4 and 1.7 nm). This discrepancy has been attributed to tip-surface interactions, image feedback settings and surface chemistry. In this work, we use standard and carbon nanotube modified AFM probes and a relatively new AFM imaging mode known as PeakForce tapping mode to establish a protocol that will allow users to accurately determine the thickness of graphene films. In particular, the error in measuring the first layer is reduced from 0.1-1.3 nm to 0.1-0.3 nm. Furthermore, in the process we establish that the graphene-substrate adsorbate layer and imaging force, in particular the pressure the tip exerts on the surface, are crucial components in the accurate measurement of graphene using AFM. These findings can be applied to other 2D materials.

  18. Estimation of total electron content (TEC) using spaceborne GPS measurements

    Choi, Key-Rok; Lightsey, E. Glenn

    2008-09-01

    TerraSAR-X (TSX), a high-resolution interferometric Synthetic Aperture Radar (SAR) mission from DLR (German Aerospace Center, Deutsches Zentrum für Luft-und Raumfahrt), was successfully launched into orbit on June 15, 2007. It includes a dual-frequency GPS receiver called IGOR (Integrated GPS Occultation Receiver), which is a heritage NASA/JPL BlackJack receiver. The software for the TSX IGOR receiver was specially-modified software developed at UT/CSR. This software was upgraded to provide enhanced occultation capabilities. This paper describes total electron content (TEC) estimation using simulation data and onboard GPS data of TerraSAR-X. The simulated GPS data were collected using the IGOR Engineering Model (EM) in the laboratory and the onboard GPS data were collected from the IGOR Flight Model (FM) on TSX. To estimate vertical total electron content (vTEC) for the simulation data, inter-frequency biases (IFB) were estimated using the "carrier to code leveling process." For the onboard GPS data, IFBs of GPS satellites were retrieved from the navigation message and applied to the measurements.

  19. How GPs implement clinical guidelines in everyday clinical practice

    Videbæk Le, Jette; Hansen, Helle P; Riisgaard, Helle;

    2015-01-01

    . OBJECTIVE: To investigate how GPs implement clinical guidelines in everyday clinical practice and how implementation approaches differ between practices. METHODS: Individual semi-structured open-ended interviews with seven GPs who were purposefully sampled with regard to gender, age and practice form....... Interviews were recorded, transcribed verbatim and then analysed using systematic text condensation. RESULTS: Analysis of the interviews revealed three different approaches to the implementation of guidelines in clinical practice. In some practices the GPs prioritized time and resources on collective......'s decision on whether and how to manage implementation. CONCLUSION: Approaches to implementation of clinical guidelines vary substantially between practices. Supporting activities should take this into account....

  20. The Effect of Helicopter Rotors on GPS Signal Reception

    Brodin, Gary; Cooper, John; Walsh, David; Stevens, Jeff

    2005-09-01

    This paper presents the results of an experiment to investigate the impact of helicopter rotor blades on GPS signal reception. An offshore transport helicopter was equipped with a measurement system including a TSO-C129 compliant receiver and a custom research receiver. GPS signals passing through rotor discs of this aircraft were found to suffer a reduction in received signal strength, leading to potential navigation and RAIM availability concerns. The phenomenon will vary between installations and receiver types. Test procedures to identify the occurrence of the phenomenon in operational GPS installations are presented, together with possible in-service monitoring programs to assess the impact on the navigation function.

  1. High-Precision Motorcycle Trajectory Measurements Using GPS

    Koyama, Yuichiro; Tanaka, Toshiyuki

    A method for measuring motorcycle trajectory using GPS is needed for simulating motorcycle dynamics. In GPS measurements of a motorcycle, both the declination of the motorcycle and obstacles near the course can cause problems. Therefore, we propose a new algorithm for GPS measurement of motorcycle trajectory. We interpolate the missing observation data within a few seconds using polynomial curves, and use a Kalman filter to smoothen position calculations. This results in obtaining trajectory with high accuracy and with sufficient continuity. The precision is equal to that of fixed point positioning, given a sufficient number of available satellites.

  2. Hybrid GPS-GSM Localization of Automobile Tracking System

    Mohammad A. Al-Khedher

    2012-01-01

    Full Text Available An integrated GPS-GSM system is proposed to track vehicles using Google Earth application. Theremote module has a GPS mounted on the moving vehicle to identify its current position, and to betransferred by GSM with other parameters acquired by the automobile’s data port as an SMS to arecipient station. The received GPS coordinates are filtered using a Kalman filter to enhance theaccuracy of measured position. After data processing, Google Earth application is used to view thecurrent location and status of each vehicle. This goal of this system is to manage fleet, policeautomobiles distribution and car theft cautions.

  3. Location Identification and Alert System in Absence of GPS

    Qurban A Memon

    2013-01-01

    There are two concerns with GPS systems. On one side, many people are becoming more aware of privacy issues that emanate from wide spread use of GPS enabled or similar systems. On the other, in absence of GPS systems emergency help is of great importance as location detection becomes not so easy. Thus, there is a need for location detection technique or a solution that not only helps in detecting location but relieves the person of the privacy concern. Such systems find widespread application...

  4. GPS network for SuperKEKB main ring

    A GPS network is being built for the SuperKEKB main rings, which lie about 11 m below the ground level. Four GPS antennas have already been installed on the roof of the access buildings to the SuperKEKB main ring tunnel. There will be three more antennas added to expand the survey network on the ground, and to compare with measurements obtained by surveying the monuments in the tunnel. Preliminary analysis indicates a good agreement between the GPS network and the underground tunnel network. This helps rebuild the alignment network destroyed by the Great East Japan earthquake. (author)

  5. Noise characteristics of Continuous GPS time series of Central and Eastern Himalaya

    Ray, J. D.; Vijayan, M. S. M.; Kumar, A.

    2015-12-01

    Global positioning system measurements with its millimetre level accuracy have been widely used to monitor the crustal dynamics. Geodetic crustal deformation studies require accurate estimate of the parameters which demands realistic estimate of the uncertainties in order to constrain the signal. GPS based crustal deformation studies in tectonically active region, such as Central and Eastern Himalaya have been carried out by several groups however, proper noise characteristics of GPS time series of this study region are unknown. In this work, we attempt to address the noise characteristics of GPS position time series by analysing the GPS time series of 22 stations from North-East India, Bhutan and Nepal Himalaya spanning 2002-2013. We have employed Spectral analysis and Maximum Likelihood Estimation (MLE) to study the noise characteristics. Power spectrum obtained by using Lomb-Scargle method reveals characteristics of white noise at the high frequencies and power law noise at lower frequencies. Estimation of the spectral index by finding the slope of the spectral curve suggests fractal white noise with overall index of -0.61. MLE was performed in two ways. First, by assuming the time series to be composed of (a) white (WN), (b) white plus flicker (FL) and (c) white plus random walk noise (WRN) and then by estimating spectral index assuming the noise to be composition of white and power law noise (WPN). The comparison of MLE values of three noise model suggest that white plus flicker noise model (FL) is the most preferred noise model. Comparison of velocity uncertainties between white noise and white plus flicker noise, obtained from MLE, suggest that velocity uncertainty is under estimated by factor of ~8 when simple white noise model is used. The spectral index estimated using MLE is -1.1 (~1) which suggests that flicker noise is the main power law noise in time series of all 22 GPS stations. A slight difference of noise amplitudes of two different monument types

  6. Mt. Etna ground deformation detected by SISTEM approach using GPS data and multiple SAR sensor

    Guglielmino, Francesco; Puglisi, Giuseppe; Bonforte, Alessandro; Cocorullo, Chiara; Sansosti, Eugenio; Pepe, Susi; Solaro, Giuseppe; Casu, Francesco; Acocella, Valerio; Ruch, Joel; Nobile, Adriano; Zoffoli, Simona

    2014-05-01

    The availability of both multiple SAR datasets and GPS stations over Mt. Etna during the 2009-2010 time span, allowed us to apply the SISTEM integration in order to capture a more complete figure of the ground deformation affecting the volcano. In particular we use both ascending and descending views of C-band ENVISAT and X-band COSMO-SkyMed sensors, and the ascending view of L-band ALOS sensors. The SAR data have been analyzed by using a time series approach, based on the SBAS technique. Moreover, thanks to the availability of dense (105 benchmarks) geodetic in situ data collected on Mt. Etna, it was possible to validate and integrate the SAR data with the GPS ground deformation data applying the SISTEM approach. The SISTEM approach simultaneously integrates all the available datasets (i.e. GPS displacement vectors on sparse benchmarks and SAR displacement maps), providing a high-resolution 3D displacement map by taking advantage of the positive features of each datasets, i.e. the availability of multiple view geometries of COSMO-SkyMed and ENVISAT data, together with the high temporal and spatial resolution of the COSMO-SkyMed data, the good coherence of ALOS L-band interferometric data, and the full 3D displacement components provided by GPS with sub-cm accuracy level. The preliminary results are consistent with the geophysical and volcanological background knowledge of the Mt. Etna dynamic during the 2009-2010 period, showing a general inflation of the entire volcanic edifice coupled with the ESE sliding of the eastern and southeastern flank. The displacement pattern, resulting by applying the SISTEM integration method, provides an accurate spatial characterization of ground deformation, well constrained by the multiple SAR data and ground GPS measurements. ALOS and COSMO-SkyMed SAR data were acquired in the framework of SAR4Volcanoes research project under Italian Space Agency agreement n. I/034/11/0. The ENVISAT data were acquired in the framework ESA CAT.1

  7. Comparison of GPS-TEC observations over Addis Ababa with IRI-2012 model predictions during 2010-2013

    Akala, A. O.; Somoye, E. O.; Adewale, A. O.; Ojutalayo, E. W.; Karia, S. P.; Idolor, R. O.; Okoh, D.; Doherty, P. H.

    2015-10-01

    This study presents Global Positioning System-Total Electron Content (GPS-TEC) observations over Addis Ababa (Lat: 9.03°N Lon: 38.77°E Mag. lat: 0.18°N) and an evaluation of the accuracy of International Reference Ionosphere-2012 (IRI-2012) model predictions during 2010-2013. Generally, on a diurnal scale, TEC recorded minimum values at 0400-0600 LT and maximum at 1400-1600 LT. Seasonally, TEC recorded maximum values during December solstice and September equinox, and minimum during June solstice. On a year-by-year basis, 2013 recorded the highest values of TEC for both the observed and the model measurements, while 2010 recorded the lowest, implying the solar activity dependence of TEC. Furthermore, we observed discrepancies in the comparison of the GPS-TEC measurements with those derived from IRI-2012 model, after the exclusion of the contributions of plasmaspheric electron content (PEC) from the GPS-observed TEC. All the three options of IRI-2012 model overestimated TEC during early morning and post-sunset hours. Comparatively, of the three options of IRI-2012 model, NeQuick appears to be the most accurate for TEC estimation over Addis Ababa, although at a very close performance capability with the IRI01 CORR option, while IRI2001 is the least accurate.

  8. GPS operations at Olkiluoto, Kivetty and Romuvaara in 2008

    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. The network of seven GPS pillars was built at Kivetty and Romuvaara during the year 1996. One pillar in each investigation area belongs to the Finnish permanent GPS network, FinnRef. A total of 26 GPS measurement campaigns have been carried out at Olkiluoto since 1995, and 17 campaigns at Kivetty and Romuvaara. 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. The networks of Kivetty and Romuvaara are quite stable expect one pillar at Romuvaara. There are seven 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. The uniform scale for the GPS measurements made in different years is the basic condition for reliable results in the deformation analyses. 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. The comparison between the GPS and EDM results can help to fix a possible scale error of the GPS measurements. 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. The local crustal deformations have been studied in GeoSatakunta project, too. This GPS network is

  9. GPS operations at Olkiluoto, Kivetty and Romuvaara in 2007

    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. The network of seven GPS pillars was built at Kivetty and Romuvaara during the year 1996. One pillar in each investigation area belongs to the Finnish permanent GPS network, FinnRef. 24 GPS measurement campaigns have been carried out at Olkiluoto since 1995, and 16 campaigns at Kivetty and Romuvaara. 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. The networks of Kivetty and Romuvaara are quite stabile expect one pillar at Romuvaara. 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 (maximum velocity is -0.22 mm/a ± 0.02 mm/a). The uniform scale for the GPS measurements made in different years is the basic condition for reliable results in the deformation analyses. At Olkiluoto a baseline for electronic distance measurements (EDM) was built in 2002. The baseline has been measured using EDM instruments simultaneously with the GPS observations. The comparison between the GPS and EDM results can solve a possible scale error of the GPS. 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, but the time series are still too short for reliable deformation studies. The local crustal deformations have been studied in GeoSatakunta project, too. This

  10. GPS operations at Olkiluoto, Kivetty and Romuvaara in 2007

    Ahola, J.; Koivula, H.; Jokela, J. (Finnish Geodetic Institute, Masala (Finland))

    2008-05-15

    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. The network of seven GPS pillars was built at Kivetty and Romuvaara during the year 1996. One pillar in each investigation area belongs to the Finnish permanent GPS network, FinnRef. 24 GPS measurement campaigns have been carried out at Olkiluoto since 1995, and 16 campaigns at Kivetty and Romuvaara. 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. The networks of Kivetty and Romuvaara are quite stabile expect one pillar at Romuvaara. 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 (maximum velocity is -0.22 mm/a +- 0.02 mm/a). The uniform scale for the GPS measurements made in different years is the basic condition for reliable results in the deformation analyses. At Olkiluoto a baseline for electronic distance measurements (EDM) was built in 2002. The baseline has been measured using EDM instruments simultaneously with the GPS observations. The comparison between the GPS and EDM results can solve a possible scale error of the GPS. 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, but the time series are still too short for reliable deformation studies. The local crustal deformations have been studied in GeoSatakunta project, too. This

  11. GPS operations at Olkiluoto, Kivetty and Romuvaara in 2008

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

    2009-09-15

    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. The network of seven GPS pillars was built at Kivetty and Romuvaara during the year 1996. One pillar in each investigation area belongs to the Finnish permanent GPS network, FinnRef. A total of 26 GPS measurement campaigns have been carried out at Olkiluoto since 1995, and 17 campaigns at Kivetty and Romuvaara. 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. The networks of Kivetty and Romuvaara are quite stable expect one pillar at Romuvaara. There are seven 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. The uniform scale for the GPS measurements made in different years is the basic condition for reliable results in the deformation analyses. 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. The comparison between the GPS and EDM results can help to fix a possible scale error of the GPS measurements. 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. The local crustal deformations have been studied in GeoSatakunta project, too. This GPS network is

  12. A More Accurate Fourier Transform

    Courtney, Elya

    2015-01-01

    Fourier transform methods are used to analyze functions and data sets to provide frequencies, amplitudes, and phases of underlying oscillatory components. Fast Fourier transform (FFT) methods offer speed advantages over evaluation of explicit integrals (EI) that define Fourier transforms. This paper compares frequency, amplitude, and phase accuracy of the two methods for well resolved peaks over a wide array of data sets including cosine series with and without random noise and a variety of physical data sets, including atmospheric $\\mathrm{CO_2}$ concentrations, tides, temperatures, sound waveforms, and atomic spectra. The FFT uses MIT's FFTW3 library. The EI method uses the rectangle method to compute the areas under the curve via complex math. Results support the hypothesis that EI methods are more accurate than FFT methods. Errors range from 5 to 10 times higher when determining peak frequency by FFT, 1.4 to 60 times higher for peak amplitude, and 6 to 10 times higher for phase under a peak. The ability t...

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

    E. Zuccheretti

    1997-06-01

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

  14. 77 FR 23668 - GPS Satellite Simulator Working Group Notice of Meeting

    2012-04-20

    ... Department of the Air Force GPS Satellite Simulator Working Group Notice of Meeting AGENCY: The United States... Global Positioning Systems (GPS) Directorate will be hosting an open GPS Satellite Simulator Working Group (SSWG) meeting for manufacturers of GPS constellation simulators utilized by the...

  15. Satellite laser ranging to GPS and GLONASS

    Sośnica, Krzysztof; Thaller, Daniela; Dach, Rolf; Steigenberger, Peter; Beutler, Gerhard; Arnold, Daniel; Jäggi, Adrian

    2015-07-01

    Satellite laser ranging (SLR) to the satellites of the global navigation satellite systems (GNSS) provides substantial and valuable information about the accuracy and quality of GNSS orbits and allows for the SLR-GNSS co-location in space. In the framework of the NAVSTAR-SLR experiment two GPS satellites of Block-IIA were equipped with laser retroreflector arrays (LRAs), whereas all satellites of the GLONASS system are equipped with LRAs in an operational mode. We summarize the outcome of the NAVSTAR-SLR experiment by processing 20 years of SLR observations to GPS and 12 years of SLR observations to GLONASS satellites using the reprocessed microwave orbits provided by the center for orbit determination in Europe (CODE). The dependency of the SLR residuals on the size, shape, and number of corner cubes in LRAs is studied. We show that the mean SLR residuals and the RMS of residuals depend on the coating of the LRAs and the block or type of GNSS satellites. The SLR mean residuals are also a function of the equipment used at SLR stations including the single-photon and multi-photon detection modes. We also show that the SLR observations to GNSS satellites are important to validate GNSS orbits and to assess deficiencies in the solar radiation pressure models. We found that the satellite signature effect, which is defined as a spread of optical pulse signals due to reflection from multiple reflectors, causes the variations of mean SLR residuals of up to 15 mm between the observations at nadir angles of 0 and 14. in case of multi-photon SLR stations. For single-photon SLR stations this effect does not exceed 1 mm. When using the new empirical CODE orbit model (ECOM), the SLR mean residual falls into the range 0.1-1.8 mm for high-performing single-photon SLR stations observing GLONASS-M satellites with uncoated corner cubes. For best-performing multi-photon stations the mean SLR residuals are between and mm due to the satellite signature effect.

  16. GPS Earthquake Early Warning in Cascadia

    Melbourne, T. I.; Scrivner, C. W.; Santillan, V. M.; Webb, F.

    2011-12-01

    Over 400 GPS receivers of the combined PANGA and PBO networks currently operate along the Cascadia subduction zone, all of which are high-rate and telemetered in real-time. These receivers span the M9 megathrust, M7 crustal faults beneath population centers, several active Cascades volcanoes, and a host of other hazard sources, and together enable a host of new approaches towards hazards mitigation. Data from the majority of the stations is received in real time at CWU and processed into one-second position estimates using 1) relative positioning within several reference frames constrained by 2) absolute point positioning using streamed satellite orbit and clock corrections. While the former produces lower-noise time series, for earthquakes greater than ~M7 and ground displacements exceeding ~20 cm, point positioning alone is shown to provide very rapid and robust estimates of the location and amplitude of both dynamic strong ground motion and permanent deformation. The advantage of point-positioning over relative positioning for earthquake applications lies primarily in the fact that each station's position is estimated independently, without double-differencing, within a reference frame defined by earth's center of mass and the satellite orbits. Point positioning does not require a nearby stable reference station or network whose motion (such as during a seismic event) aliases directly into fictitious displacement of any station in question. Thus, for real-time GPS earthquake characterization, this is of great importance in ensuring a robust measurement. We are now producing real-time point-positions using GIPSY5 and corrections to broadcast satellite clocks and orbits streamed live from the DLR in Germany. We have also developed a stream-editor to flag and fix cycle-slips and other data problems on the fly prior to positioning. We are achieving Whidbey Island, Bainbridge, and Portland West Hills). For the megathrust slip estimation, we also predict sea

  17. High quality reprocessed GPS Zenith Total Delay dataset over Europe

    Pacione, Rosa; Pace, Brigida; Bianco, Giuseppe

    2015-04-01

    The present availability of 18 years of GPS data belonging to the European Permanent Network (EPN, http://www.epncb.oma.be/) is a valuable database for the development of a climate data record of GPS tropospheric products. We homogeneously reprocessed the whole EPN network for the period 1996-2013 in a consistent way using GIPSY-OASIS II software and applying the state-of-the-art models. This ongoing reprocessing effort, part of the EPN Repro2 initiative, will provide a GPS climate data record over Europe with high potential for monitoring trend and variability in atmospheric water vapour thus improving the knowledge of climatic trends of atmospheric water vapour, being useful for global and regional NWP reanalyses and climate model simulations. These reprocessed ZTD time series will be evaluated against radiosonde data as well as independently reprocessed GPS ZTD time-series.

  18. Application of differential GPS to civil helicopter terminal guidance

    Denaro, R. P.

    1984-01-01

    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. Applications with very demanding accuracy requirements are related to remote area search and rescue, offshore oil platform approach, remote area precision landing, and other precise navigation operations. Differential GPS appears to provide a solution for meeting the accuracy requirements involved in the considered operations. The present investigation is concerned with results obtained in three areas studied in connection with the conducted research program. Attention is given to mission-tailored satellite selection, a satellite selection algorithm concept, satellite selection algorithm simulation results, and differential GPS ground station design.

  19. Using cluster analysis to organize and explore regional GPS velocities

    Simpson, Robert W.; Thatcher, Wayne; Savage, James C.

    2012-01-01

    Cluster analysis offers a simple visual exploratory tool for the initial investigation of regional Global Positioning System (GPS) velocity observations, which are providing increasingly precise mappings of actively deforming continental lithosphere. The deformation fields from dense regional GPS networks can often be concisely described in terms of relatively coherent blocks bounded by active faults, although the choice of blocks, their number and size, can be subjective and is often guided by the distribution of known faults. To illustrate our method, we apply cluster analysis to GPS velocities from the San Francisco Bay Region, California, to search for spatially coherent patterns of deformation, including evidence of block-like behavior. The clustering process identifies four robust groupings of velocities that we identify with four crustal blocks. Although the analysis uses no prior geologic information other than the GPS velocities, the cluster/block boundaries track three major faults, both locked and creeping.

  20. Studies on Precise Spacecraft Navigation and Positioning Using GPS

    XiangKaiheng; QuGuangji

    2004-01-01

    GPS measurement technology, Encke method to solve satellite orbit perturbation and generalized Kalman filtering technology are organically combined together, and an innovative solution—carrier phase & pseudorange integrated dynamic orbit determination (CPPIDOD) for low earth orbit spacecraft on-board autonomous precise navigation and positioning by using GPS is presented. The difficult problems of dynamically resolving integer ambiguities and amendment of cycle slips in the application of GPS carrier phase have been solved.Based on all above, the technique of carrier phase & pseudorange integrated dynamic differential relative navigation between two spacecrafts is brought forward. Results of numerical simulation analyses and senti-physical simulation tests show that the solutions presented in this paper are feasible, which can significantly improve the performance of GPS positioning, and the models, algorithms and software are practical for engineering use.

  1. GPS Source Solution of the 2004 Parkfield Earthquake

    Houlie, N.; Dreger, D. S.; Kim, A.

    2014-12-01

    We compute a series of finite-source parameter inversions of the fault rupture of the 2004 Parkfield earthquake based on 1 Hz GPS records only. We confirm that some of the co-seismic slip at shallow depth (>5 km) constrained by InSAR data processing results from early post-seismic deformation. We also show 1) that if located very close to the rupture, a GPS receiver can saturate while it remains possible to estimate the ground velocity (~1.2 m/s) near the fault, 2) that GPS waveforms inversions constrain that the slip distribution at depth even when GPS monuments are not located directly above the ruptured areas and 3) the slip distribution at depth from our best models agree with that recovered from strong motion data. The 95th percentile of the slip amplitudes for rupture velocities ranging from 2 to 5 km/s is ~55+/-6 cm.

  2. GPS source solution of the 2004 Parkfield earthquake

    Houlie, N; Kim, A

    2014-01-01

    We compute a series of finite-source parameter inversions of the fault rupture of the 2004 Parkfield earthquake based on 1 Hz GPS records only. We confirm that some of the co-seismic slip at shallow depth (<5 km) constrained by InSAR data processing results from early post-seismic deformation. We also show 1) that if located very close to the rupture, a GPS receiver can saturate while it remains possible to estimate the ground velocity (~1.2 m/s) near the fault, 2) that GPS waveforms inversions constrain that the slip distribution at depth even when GPS monuments are not located directly above the ruptured areas and 3) the slip distribution at depth from our best models agree with that recovered from strong motion data. The 95th percentile of the slip amplitudes for rupture velocities ranging from 2 to 5 km/s is, 55 +/- 6 cm.

  3. DARPA looks beyond GPS for positioning, navigating, and timing

    Cold-atom interferometry, microelectromechanical systems, signals of opportunity, and atomic clocks are some of the technologies the defense agency is pursuing to provide precise navigation when GPS is unavailable

  4. ISOLDE target zone GPS robot, Camera B Part2 HD

    2016-01-01

    Sequences of the ISOLDE GPS robot movements mainly in close up moving a target along the corridor and onto a shelf position and vice versa. Close up GPS robot handling at exchange point. Movement GPS robot with target through the corridor. Close up robot cable guidance system. Close up posing target on the shelf position. Close up picking up a target from the shelf position and passing through corridor. Picking up a target from a shelf position seen from the target front end towards the zone entrance and taking it to the exchange point and vice versa. Checking activation: GPS robot picking up a target from the shelf and moving it in front of the radiation monitor and close up.

  5. ISOLDE target zone GPS robot Camera B Part1 HD

    2016-01-01

    Sequences of the ISOLDE GPS robot movements mainly in close up moving a target along the corridor and onto a shelf position and vice versa. Close up GPS robot handling at exchange point. Movement GPS robot with target through the corridor. Close up robot cable guidance system. Close up posing target on the shelf position. Close up picking up a target from the shelf position and passing through corridor. Picking up a target from a shelf position seen from the target front end towards the zone entrance and taking it to the exchange point and vice versa. Checking activation: GPS robot picking up a target from the shelf and moving it in front of the radiation monitor and close up.

  6. Deployment of Autonomous GPS Stations in Marie Byrd Land, Antartica

    Donnellan, A.; Luyendyk, B.; Smith, M.; Dace, G.

    1999-01-01

    During the 1998-1999 Antarctic field season, we installed three autonomous GPS stations in Marie Byrd Land, West Antarctica to measure glacio-isostatic rebound and rates of spreading across the West Antartic Rift System.

  7. GPS SATELLITE SIMULATOR SIGNAL ESTIMATION BASED ON ANN

    2005-01-01

    Multi-channel Global Positioning System (GPS) satellite signal simulator is used to provide realistic test signals for GPS receivers and navigation systems. In this paper, signals arriving the antenna of GPS receiver are analyzed from the viewpoint of simulator design. The estimation methods are focused of which several signal parameters are difficult to determine directly according to existing experiential models due to various error factors. Based on the theory of Artificial Neural Network (ANN), an approach is proposed to simulate signal propagation delay,carrier phase, power, and other parameters using ANN. The architecture of the hardware-in-the-loop test system is given. The ANN training and validation process is described. Experimental results demonstrate that the ANN designed can statistically simulate sample data in high fidelity.Therefore the computation of signal state based on this ANN can meet the design requirement,and can be directly applied to the development of multi-channel GPS satellite signal simulator.

  8. Real null coframes in general relativity and GPS type coordinates

    Some time ago, Finkelstein defined a 'symmetric' null frame with four real null vectors. We discuss this Finkelstein frame and show that a similarly defined real null coframe is closely related to the GPS type coordinates recently introduced by Rovelli

  9. ISOLDE target zone GPS robot Camera B Part1

    2016-01-01

    Sequences of the ISOLDE GPS robot movements mainly in close up moving a target along the corridor and onto a shelf position and vice versa. Close up GPS robot handling at exchange point. Movement GPS robot with target through the corridor. Close up robot cable guidance system. Close up posing target on the shelf position. Close up picking up a target from the shelf position and passing through corridor. Picking up a target from a shelf position seen from the target front end towards the zone entrance and taking it to the exchange point and vice versa. Checking activation: GPS robot picking up a target from the shelf and moving it in front of the radiation monitor and close up.

  10. ISOLDE target zone GPS robot, Camera B Part2

    2016-01-01

    Sequences of the ISOLDE GPS robot movements mainly in close up moving a target along the corridor and onto a shelf position and vice versa. Close up GPS robot handling at exchange point. Movement GPS robot with target through the corridor. Close up robot cable guidance system. Close up posing target on the shelf position. Close up picking up a target from the shelf position and passing through corridor. Picking up a target from a shelf position seen from the target front end towards the zone entrance and taking it to the exchange point and vice versa. Checking activation: GPS robot picking up a target from the shelf and moving it in front of the radiation monitor and close up.

  11. A Mobile GPS Application: Mosque Tracking with Prayer Time Synchronization

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

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

  12. GPS baseline configuration design based on robustness analysis

    Yetkin, M.; Berber, M.

    2012-11-01

    The robustness analysis results obtained from a Global Positioning System (GPS) network are dramatically influenced by the configurationof the observed baselines. The selection of optimal GPS baselines may allow for a cost effective survey campaign and a sufficiently robustnetwork. Furthermore, using the approach described in this paper, the required number of sessions, the baselines to be observed, and thesignificance levels for statistical testing and robustness analysis can be determined even before the GPS campaign starts. In this study, wepropose a robustness criterion for the optimal design of geodetic networks, and present a very simple and efficient algorithm based on thiscriterion for the selection of optimal GPS baselines. We also show the relationship between the number of sessions and the non-centralityparameter. Finally, a numerical example is given to verify the efficacy of the proposed approach.

  13. Software Defined GPS Receiver for International Space Station

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

    2011-01-01

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

  14. New GPS constraints on the kinematics of the Apennines subduction

    Devoti, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Riguzzi, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Cuffaro, M.; Igag, CNR; Doglioni, C.; La Sapienza University

    2008-01-01

    We present the velocity field of the Italian area derived from continuous GPS observations from 2003 to 2007. The GPS sites were installed by different institutions and for different purposes; they cover the whole country with a mean inter-site distance of about 60 km and provide a valuable source of data to map the present day kinematics of the region. The absolute ITRF2005 rotation poles and rates of Eurasia, Africa and Adriatic plates are estimated, to study the kinematics a...

  15. GPS and Glonass Combined Static Precise Point Positioning (ppp)

    Pandey, D.; Dwivedi, R.; Dikshit, O.; Singh, A. K.

    2016-06-01

    With the rapid development of multi-constellation Global Navigation Satellite Systems (GNSSs), satellite navigation is undergoing drastic changes. Presently, more than 70 satellites are already available and nearly 120 more satellites will be available in the coming years after the achievement of complete constellation for all four systems- GPS, GLONASS, Galileo and BeiDou. The significant improvement in terms of satellite visibility, spatial geometry, dilution of precision and accuracy demands the utilization of combining multi-GNSS for Precise Point Positioning (PPP), especially in constrained environments. Currently, PPP is performed based on the processing of only GPS observations. Static and kinematic PPP solutions based on the processing of only GPS observations is limited by the satellite visibility, which is often insufficient for the mountainous and open pit mines areas. One of the easiest options available to enhance the positioning reliability is to integrate GPS and GLONASS observations. This research investigates the efficacy of combining GPS and GLONASS observations for achieving static PPP solution and its sensitivity to different processing methodology. Two static PPP solutions, namely standalone GPS and combined GPS-GLONASS solutions are compared. The datasets are processed using the open source GNSS processing environment gLAB 2.2.7 as well as magicGNSS software package. The results reveal that the addition of GLONASS observations improves the static positioning accuracy in comparison with the standalone GPS point positioning. Further, results show that there is an improvement in the three dimensional positioning accuracy. It is also shown that the addition of GLONASS constellation improves the total number of visible satellites by more than 60% which leads to the improvement of satellite geometry represented by Position Dilution of Precision (PDOP) by more than 30%.

  16. Degradation of GPS performance in geomagnetically disturbed conditions

    Afraimovich, E L; Kondakova, T N

    2002-01-01

    The GPS performance is impaired in conditions of geomagnetic distrubances. The rms error of positioning accuracy increases in the case where two-frequency GPS receivers of three main types (ASHTECH, TRIMBLE, and AOA) are in operation. For ASHTECH receivers (unlike AOA and TRIMBLE) there is also a clear correlation between the slip density of the one- and two-frequency modes of positioning and the level of geomagnetic disturbance.

  17. Voice and GPS Based Navigation System For Visually Impaired

    Harsha Gawari; Prof. Meeta Bakuli

    2014-01-01

    The paper represents the architecture and implementation of a system that will help in the navigation of the visually impaired people. The system that we have designed uses GPS and voice recognition along with obstacle avoidance for the purpose of guiding visually impaired. The visually impaired person issues the command and receives the direction response using audio signals. The latitude and longitude values are received continuously from the GPS receiver. The directions are given to the us...

  18. Custom GPS-Correction Server for Real-Time Trajectography

    Gontran, Hervé

    2006-01-01

    Centimeter-level real-time kinematic (RTK) positioning is one of the most widely used surveying techniques. Broadcasting GPS-RTK corrections via Internet-based services has become a new communication procedure to achieve “instantaneous” positioning with high accuracy. This procedure generally involves a Virtual Reference Station (VRS), the data of which are derived from a network of GPS stations continuously linked to a control center. Its public implementation implies GDGPS (NASA Global Diff...

  19. SECURE TRACKING AND TRANSPORT SYSTEM USING RWP AND GPS

    Silky Verma; Ritika Markanday; Sonakshi Kalia; Prof.Nallakaruppan.M.K

    2013-01-01

    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 a...

  20. Performance of GPS Stochastic Modeling for Forest Environment

    Erenoğlu, R. Cüneyt

    2012-01-01

    The Global Positioning System (GPS) now makes it possible to define forest boundaries using double differenced carrier phase observables. They are mostly processed with algorithms based on the Least- quares Estimation (LSE). Although GPS was completely developed for outdoor navigation, sometimes it can be used in near/under tree or building shading. In such a case, before applying the LSE, both the functional and stochastic models should be properly defined in order to obtain reliable positio...

  1. ISOLDE target zone GPS robot, Camera A Part2 HD

    2016-01-01

    Sequences of the ISOLDE GPS robot movements along the corridor picking up an ISOLDE target from one of the shelfs behind the lead shielding doors and moving it to the exchange point. Several movements of the ISOLDE GPS robot from different angles with and without target along the corridor as well as posing and taking the target from the shelf and posing it onto the exchange point.

  2. ISOLDE target zone GPS robot, Camera A Part1 HD

    2016-01-01

    Sequences of the ISOLDE GPS robot movements along the corridor picking up an ISOLDE target from one of the shelfs behind the lead shielding doors and moving it to the exchange point. Several movements of the ISOLDE GPS robot from different angles with and without target along the corridor as well as posing and taking the target from the shelf and posing it onto the exchange point.

  3. GPS Technology for the Development of Business Information Systems

    Muresan, Mihaela

    2006-01-01

    The use of the GPS system opens the way for a new generation of information systems using geospatial information. The geoinformation provided by the GPS system could be used in various applications, such as: positioning and monitoring the behavior of the objects static or in movement, navigating, measuring the surfaces etc. These new approach introduces the concept of image handling for decision support which involves a better geoimage handling in order to make easier for decision makers to d...

  4. RFID, GPS & GSM Based Vehicle Tracing & Employee Security System

    Ms.S.S. Pethakar, Prof. N. Srivastava, Ms.S.D. Suryawanshi

    2012-01-01

    A RFID, GPS & GSM Based Vehicle Tracking and Employee Security System combine the installation of an electronic device in a vehicle, with purpose-designed computer software to enable the company to track the vehicle's location. In vehicle tracking systems we use Global Positioning System (GPS) technology for locating the vehicle. Vehicle information can be viewed on electronic maps via the Internet or specialized software. Due to recently happened mishaps such as burglary, rape cases etc., t...

  5. Using Transponders on the Moon to Increase Accuracy of GPS

    Penanen, Konstantin; Chui, Talso

    2008-01-01

    It has been proposed to place laser or radio transponders at suitably chosen locations on the Moon to increase the accuracy achievable using the Global Positioning System (GPS) or other satellite-based positioning system. The accuracy of GPS position measurements depends on the accuracy of determination of the ephemerides of the GPS satellites. These ephemerides are determined by means of ranging to and from Earth-based stations and consistency checks among the satellites. Unfortunately, ranging to and from Earth is subject to errors caused by atmospheric effects, notably including unpredictable variations in refraction. The proposal is based on exploitation of the fact that ranging between a GPS satellite and another object outside the atmosphere is not subject to error-inducing atmospheric effects. The Moon is such an object and is a convenient place for a ranging station. The ephemeris of the Moon is well known and, unlike a GPS satellite, the Moon is massive enough that its orbit is not measurably affected by the solar wind and solar radiation. According to the proposal, each GPS satellite would repeatedly send a short laser or radio pulse toward the Moon and the transponder(s) would respond by sending back a pulse and delay information. The GPS satellite could then compute its distance from the known position(s) of the transponder(s) on the Moon. Because the same hemisphere of the Moon faces the Earth continuously, any transponders placed there would remain continuously or nearly continuously accessible to GPS satellites, and so only a relatively small number of transponders would be needed to provide continuous coverage. Assuming that the transponders would depend on solar power, it would be desirable to use at least two transponders, placed at diametrically opposite points on the edges of the Moon disk as seen from Earth, so that all or most of the time, at least one of them would be in sunlight.

  6. Environmental radiation monitoring system with GPS (global positioning system)

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

  7. Can RTK GPS be Used to Improve Cadastral Infrastructure?

    Craig Roberts; Thomas Grinter; Volker Janssen

    2011-01-01

    Cadastral surveying is concerned with the process of gathering evidence in the form of position information that is used to define the location of objects or land boundaries for the purposes of identifying ownership and/or the value of land parcels. The advent of Global Navigation Satellite Systems (GNSS), such as the Global Positioning System (GPS), has revolutionised the way 3-dimensional positions are determined and GPS surveying techniques, particularly Real Time Kinematic (RTK), are incr...

  8. DOC questionnaire: measuring how GPs and medical specialists rate collaboration

    Berendsen, A.J.; Benneker, W.H.; Groenier, K. H.; Schuling, J.; Grol, R P; Meyboom-de Jong, B

    2010-01-01

    PURPOSE: This paper aims to assess the validity of a questionnaire aimed at assessing how general practitioners (GPs) and specialists rate collaboration. DESIGN/METHODOLOGY/APPROACH: Primary data were collected in The Netherlands during March to September 2006. A cross-sectional study was conducted among 259 GPs and 232 specialists. Participants were randomly selected from The Netherlands Medical Address Book. Specialists rarely contacting a GP were not invited to participate. FINDINGS: Explo...

  9. ISOLDE target zone GPS robot, Camera A Part2

    2016-01-01

    Sequences of the ISOLDE GPS robot movements along the corridor picking up an ISOLDE target from one of the shelfs behind the lead shielding doors and moving it to the exchange point. Several movements of the ISOLDE GPS robot from different angles with and without target along the corridor as well as posing and taking the target from the shelf and posing it onto the exchange point.

  10. ISOLDE target zone GPS robot, Camera A Part1

    2016-01-01

    Sequences of the ISOLDE GPS robot movements along the corridor picking up an ISOLDE target from one of the shelfs behind the lead shielding doors and moving it to the exchange point. Several movements of the ISOLDE GPS robot from different angles with and without target along the corridor as well as posing and taking the target from the shelf and posing it onto the exchange point.

  11. Real time on-the-fly kinematic GPS

    Roberts, Gethin Wyn

    1997-01-01

    Considerable interest has been show in the development and application of real time On-The-Fly (OTF) kinematic GPS. A major error source and limitation of such a positioning technique is that caused by cycle slips. When these occur, the integer ambiguities must be resolved for, which can take hundreds of epochs to complete depending on satellite availability and geometry. This research has focused on investigating the applications of real time OTF GPS, as well as its limitations and preci...

  12. Il sistema informativo territoriale della Rete Integrata Nazionale GPS (RING)

    Pignone, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Moschillo, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Avallone, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Cecere, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; D'Ambrosio, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Zarrilli, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia

    2009-01-01

    Since 2004, an important technological infrastructure has been created in Italy by INGV in order to investigate active tectonics targets. A Continuous GPS network constituted by about 130 stations has been deployed all over Italy. The development and the realization of a stable GPS monumentation, the integration with other classical seismological instruments and the choice of both satellite and internet data transmission make this network one of the most innovative and relia...

  13. Il Sistema Informativo Territoriale della Rete Integrata Nazionale GPS (RING)

    Pignone, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Moschillo, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Avallone, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Cecere, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; D'Ambrosio, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; D'Anastasio, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Zarrilli, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia

    2008-01-01

    Since 2004, an important technological infrastructure has been created in Italy by INGV in order to investigate active tectonics targets. A Continuous GPS network constituted by about 130 stations has been deployed all over Italy. The development and the realization of a stable GPS monumentation, the integration with other classical seismological instruments and the choice of both satellite and internet data transmission make this network one of the most innovative and reliable CGPS networks ...

  14. Mapeamento da Araucaria angustifolia utilizando receptores GPS

    Diego Luis Venancio

    2010-09-01

    Full Text Available This study makes use of GPS technology in differential mode (relative positioning and absolute mode in a MixedOmbrophilous Forest in order to map the Araucaria angustifolia trees that occur in the area of study (Campus of Irati - UNICENTROin Paraná State, Brazil. The fieldwork pointed out the presence of 264 Araucárias in the area of study, the relative positioning waspossible in 141 cases with precision ranging from 6 to 84 cm; absolute positioning was possible in all cases with precision rangingfrom 5 to 14 m. The relative positioning was possible in 30% of the Araucárias where slope was > 30% and in 57% of cases in whichthe basal area was > 16 m2/ha. It can be concluded that the relative positioning accuracy is sufficient for the location of the Araucárias,while the absolute position can cause confusion due to the low degree of planimetric accuracy position. The results of the relativepositioning were influenced by slope and basal area, especially in conditions of high slope and high basal area.

  15. Inferring Taxi Status Using GPS Trajectories

    Zhu, Yin; Zhang, Liuhang; Santani, Darshan; Xie, Xing; Yang, Qiang

    2012-01-01

    In this paper, we infer the statuses of a taxi, consisting of occupied, non-occupied and parked, in terms of its GPS trajectory. The status information can enable urban computing for improving a city's transportation systems and land use planning. In our solution, we first identify and extract a set of effective features incorporating the knowledge of a single trajectory, historical trajectories and geographic data like road network. Second, a parking status detection algorithm is devised to find parking places (from a given trajectory), dividing a trajectory into segments (i.e., sub-trajectories). Third, we propose a two-phase inference model to learn the status (occupied or non-occupied) of each point from a taxi segment. This model first uses the identified features to train a local probabilistic classifier and then carries out a Hidden Semi-Markov Model (HSMM) for globally considering long term travel patterns. We evaluated our method with a large-scale real-world trajectory dataset generated by 600 taxis...

  16. Inferring Directed Road Networks from GPS Traces by Track Alignment

    Xingzhe Xie

    2015-11-01

    Full Text Available This paper proposes a method to infer road networks from GPS traces. These networks include intersections between roads, the connectivity between the intersections and the possible traffic directions between directly-connected intersections. These intersections are localized by detecting and clustering turning points, which are locations where the moving direction changes on GPS traces. We infer the structure of road networks by segmenting all of the GPS traces to identify these intersections. We can then form both a connectivity matrix of the intersections and a small representative GPS track for each road segment. The road segment between each pair of directly-connected intersections is represented using a series of geographical locations, which are averaged from all of the tracks on this road segment by aligning them using the dynamic time warping (DTW algorithm. Our contribution is two-fold. First, we detect potential intersections by clustering the turning points on the GPS traces. Second, we infer the geometry of the road segments between intersections by aligning GPS tracks point by point using a “stretch and then compress” strategy based on the DTW algorithm. This approach not only allows road estimation by averaging the aligned tracks, but also a deeper statistical analysis based on the individual track’s time alignment, for example the variance of speed along a road segment.

  17. Foundation of Digital Manufacture——The Improved GPS System

    CUI Changcai; JIANG Xiangqian; LIU Xiaojun; LI Zhu

    2006-01-01

    The geometrical product specifications and verification (GPS) system is an engineering tool for product development and manufacture. The new GPS standard system is necessary, as companies are rapidly moving ahead with new technologies, new manufacturing processes, new materials and visionary products in an environment of international outsourcing. The GPS system takes the complete life cycle of a product from function requirements, design, manufacturing to verification into account. The matrix framework of the new GPS is masterplanned under one main line and two kinds of correlation. The main line is based on specifications concerning the whole production process. And two kinds of correlation are the expanded uncertainties and duality principle-based operators. They are two important tools for manufacture production and there are other concepts and definitions proposed in the new GPS that differ from the traditional geometrical standards. The paper discusses the improved GPS system about its background, characteristics, framework and some important concepts, which will present a clear and impressive standard system for the digital manufacture.

  18. High Frequency GPS sources in the AT20G Survey

    Hancock, P J

    2009-01-01

    The Australia Telescope 20GHz (AT20G) survey was used to select a complete sample of 656 Gigahertz Peaked Spectrum (GPS) sources with spectral turnovers above 5GHz. The AT20G has near simultaneous observations at 4.8, 8.6 and 20GHz, which makes it possible to exclude flat spectrum variability as a cause of a source's peaked spectrum. Optical identification of the sample results in 361 QSOs and 104 galaxies and 191 blank fields. Redshifts are known for 104 of the GPS sources. The GPS sources from the AT20G are discussed and compared to previously known samples. The new sample of high frequency peaking GPS sources is found at a lower redshift than previous samples and to also have a lower 5GHz radio power. Evidence is found to support the idea that the origin of the GPS spectral shape are intrinsically different for galaxies and QSOs. This paper is an elaboration and extension of the talk given at the $4^{th}$ CSS/GPS conference in Riccione in May 2008.

  19. Application of GPS in a high precision engineering survey network

    A GPS satellite survey was carried out with the Macrometer to support construction at the Stanford Linear Accelerator Center (SLAC). The network consists of 16 stations of which 9 stations were part of the Macrometer network. The horizontal and vertical accuracy of the GPS survey is estimated to be 1 to 2 mm and 2 to 3 mm respectively. The horizontal accuracy of the terrestrial survey, consisting of angles and distances, equals that of the GPS survey only in the ''loop'' portion of the network. All stations are part of a precise level network. The ellipsoidal heights obtained from the GPS survey and the orthometric heights of the level network are used to compute geoid undulations. A geoid profile along the linac was computed by the National Geodetic Survey in 1963. This profile agreed with the observed geoid within the standard deviation of the GPS survey. Angles and distances were adjusted together (TERRA), and all terrestrial observations were combined with the GPS vector observations in a combination adjustment (COMB). A comparison of COMB and TERRA revealed systematic errors in the terrestrial solution. A scale factor of 1.5 ppM +- .8 ppM was estimated. This value is of the same magnitude as the over-all horizontal accuracy of both networks. 10 refs., 3 figs., 5 tabs

  20. Kinematic GPS survey as validation of LIDAR strips accuracy

    C. Gordini

    2006-06-01

    Full Text Available As a result of the catastrophic hydrogeological events which occurred in May 1998 in Campania, in the south of Italy, the distinctive features of airborne laser scanning mounted on a helicopter were used to survey the landslides at Sarno and Quindici. In order to survey the entire zone of interest, approximately 21 km2, it was necessary to scan 12 laser strips. Many problems arose during the survey: difficulties in receiving the GPS signal, complex terrain features and unfavorable atmospheric conditions. These problems were investigated and it emerged that one of the most influential factors is the quality of GPS signals. By analysing the original GPS data, the traces obtained by fixing phase ambiguity with an On The Fly (OTF algorithm were isolated from those with smoothed differential GPS solution (DGPS. Processing and analysis of laser data showed that not all the overlapping laser strips were congruent with each other. Since an external survey to verify the laser data accuracy was necessary, it was decided to utilize the kinematic GPS technique. The laser strips were subsequently adjusted, using the kinematic GPS data as reference points. Bearing in mind that in mountainous areas like the one studied here it is not possible to obtain nominal precision and accuracy, a good result was nevertheless obtained with a Digital Terrain Model (DTM of all the zones of interest.

  1. Studying Landslide Displacements in Megamendung (Indonesia Using GPS Survey Method

    Hasanuddin Z. Abidin

    2004-11-01

    Full Text Available Landslide is one of prominent geohazards that frequently affects Indonesia, especially in the rainy season. It destroys not only environment and property, but usually also causes deaths. Landslide monitoring is therefore very crucial and should be continuously done. One of the methods that can have a contribution in studying landslide phenomena is repeated GPS survey method. This paper presents and discusses the operational performances, constraints and results of GPS surveys conducted in a well known landslide prone area in West Java (Indonesia, namely Megamendung, the hilly region close to Bogor. Three GPS surveys involving 8 GPS points have been conducted, namely on April 2002, May 2003 and May 2004, respectively. The estimated landslide displacements in the area are relatively quite large in the level of a few dm to a few m. Displacements up to about 2-3 m were detected in the April 2002 to May 2003 period, and up to about 3-4 dm in the May 2003 to May 2004 period. In both periods, landslides in general show the northwest direction of displacements. Displacements vary both spatially and temporally. This study also suggested that in order to conclude the existence of real and significant displacements of GPS points, the GPS estimated displacements should be subjected to three types of testing namely: the congruency test on spatial displacements, testing on the agreement between the horizontal distance changes with the predicted direction of landslide displacement, and testing on the consistency of displacement directions on two consecutive periods.

  2. GPS Sounding of the Atmosphere from Low Earth Orbit: Preliminary Results.

    Ware, R.; Rocken, C.; Solheim, F.; Exner, M.; Schreiner, W.; Anthes, R.; Feng, D.; Herman, B.; Gorbunov, M.; Sokolovskiy, S.; Hardy, K.; Kuo, Y.; Zou, X.; Trenberth, K.; Meehan, T.; Melbourne, W.; Businger, S.

    1996-01-01

    Halogen Occultation Experiment was available for comparison. These comparisons show that accurate vertical temperature profiles may be obtained using the GPS limb sounding technique from approximately 40 km to about 5-7 km in altitude where moisture effects are negligible. Temperatures in this region usually agree within 2°C with the independent sources of data. The GPS/MET temperature profiles show vertical resolution of about 1 km and resolve the location and minimum temperature of the tropopause very well. Theoretical temperature accuracy is better than 0.5°C at the tropopause, degrading to about 1°C at 40-km altitude.Above 40 km and below 5 km, these preliminary temperature retrievals show difficulties. In the upper atmosphere, the errors result from initial temperature and pressure assumptions in this region and initial ionospheric refraction assumptions. In the lower troposphere, the errors appear to be associated with multipath effects caused by large gradients in refractivity primarily due to water vapor distribution.

  3. Operational GPS Imaging System at Multiple Scales for Earth Science and Monitoring of Geohazards

    Blewitt, Geoffrey; Hammond, William; Kreemer, Corné

    2016-04-01

    Toward scientific targets that range from slow deep Earth processes to geohazard rapid response, our operational GPS data analysis system produces smooth, yet detailed maps of 3-dimensional land motion with respect to our Earth's center of mass at multiple spatio-temporal scales with various latencies. "GPS Imaging" is implemented operationally as a back-end processor to our GPS data processing facility, which uses JPL's GIPSY OASIS II software to produce positions from 14,000 GPS stations in ITRF every 5 minutes, with coordinate precision that gradually improves as latency increases upward from 1 hour to 2 weeks. Our GPS Imaging system then applies sophisticated signal processing and image filtering techniques to generate images of land motion covering our Earth's continents with high levels of robustness, accuracy, spatial resolution, and temporal resolution. Techniques employed by our GPS Imaging system include: (1) similarity transformation of polyhedron coordinates to ITRF with optional common-mode filtering to enhance local transient signal to noise ratio, (2) a comprehensive database of ~100,000 potential step events based on earthquake catalogs and equipment logs, (3) an automatic, robust, and accurate non-parametric estimator of station velocity that is insensitive to prevalent step discontinuities, outliers, seasonality, and heteroscedasticity; (4) a realistic estimator of velocity error bars based on subsampling statistics; (5) image processing to create a map of land motion that is based on median spatial filtering on the Delauney triangulation, which is effective at despeckling the data while faithfully preserving edge features; (6) a velocity time series estimator to assist identification of transient behavior, such as unloading caused by drought, and (7) a method of integrating InSAR and GPS for fine-scale seamless imaging in ITRF. Our system is being used to address three main scientific focus areas, including (1) deep Earth processes, (2

  4. Feasibility of Construction of the Continuously Operating Geodetic GPS Network of Sinaloa, Mexico

    Vazquez, G. E.; Jacobo, C.

    2011-12-01

    This research is based on the study and analysis of feasibility for the construction of the geodetic network for GPS continuous operation for Sinaloa, hereafter called (RGOCSIN). A GPS network of continuous operation is defined as that materialized structure physically through permanent monuments where measurements to the systems of Global Positioning (GPS) is performed continuously throughout a region. The GPS measurements in this network are measurements of accuracy according to international standards to define its coordinates, thus constituting the basic structure of geodetic referencing for a country. In this context is that in the near future the RGOCSIN constitutes a system state only accurate and reliable georeferencing in real-time (continuous and permanent operation) and will be used for different purposes; i.e., in addition to being fundamental basis for any lifting topographic or geodetic survey, and other areas such as: (1) Different construction processes (control and monitoring of engineering works); (2) Studies of deformation of the Earth's crust (before and after a seismic event); (3) GPS meteorology (weather forecasting); (4) Demarcation projects (natural and political); (5) Establishment of bases to generate mapping (necessary for the economic and social development of the state); (6) Precision agriculture (optimization of economic resources to the various crops); (7) Geographic information systems (Organization and planning activities associated with the design and construction of public services); (8) Urban growth (possible settlements in the appropriate form and taking care of the environmental aspect), among others. However there are criteria and regulations according to the INEGI (Instituto Nacional de Estadística y Geografía, http://www.inegi.org.mx/) that must be met; even for this stage of feasibility of construction that sees this project as a first phase. The fundamental criterion to be taken into account according to INEGI is a

  5. Comparison of time series of integrated water vapor measured using radiosonde, GPS and microwave radiometer at the CNR-IMAA Atmospheric Observatory

    Amato, Franceso; Rosoldi, Marco; Madonna, Fabio

    2015-04-01

    Information about the amount and spatial distribution of atmospheric water vapor is essential to improve our knowledge of weather forecasting and climate change. Water vapor is highly variable in space and time depending on the complex interplay of several phenomena like convection, precipitation, turbulence, etc. It remains one of the most poorly characterized meteorological parameters. Remarkable progress in using of Global Navigation Satellite Systems (GNSS), in particular GPS, for the monitoring of atmospheric water vapor has been achieved during the last decades. Various studies have demonstrated that GPS could provide accurate water vapor estimates for the study of the atmosphere. Different GPS data processing provided within the scientific community made use of various tropospheric models that primarily differs for the assumptions on the vertical refractivity profiles and the mapping of the vertical delay with elevation angles. This works compares several models based on the use of surface meteorological data. In order to calculate the Integrated Water Vapour (IWV), an algorithm for calculating the zenith tropospheric delay was implemented. It is based upon different mapping functions (Niell, Saastamoinen, Chao and Herring Mapping Functions). Observations are performed at the Istituto di Metodologie per l'Analisi Ambientale (IMAA) GPS station located in Tito Scalo, Potenza (40.60N, 15.72E), from July to December 2014, in the framework of OSCAR project (Observation System for Climate Application at Regional scale). The retrieved values of the IWV using the GPS are systematically compared with the other estimation of IWV collected at CIAO (CNR-IMAA Atmospheric Observatory) using the other available measurement techniques. In particular, in this work the compared IWV are retrieved from: 1. a Trimble GPS antenna (data processed by the GPS-Met network, see gpsmet.nooa.gov); 2. a Novatel GPS antenna (data locally processed using a software developed at CIAO); 3

  6. Doppler Lidar Sensor for Precision Navigation in GPS-Deprived Environment

    Amzajerdian, F.; Pierrottet, D. F.; Hines, G. D.; Hines, G. D.; Petway, L. B.; Barnes, B. W.

    2013-01-01

    Landing mission concepts that are being developed for exploration of solar system bodies are increasingly ambitious in their implementations and objectives. Most of these missions require accurate position and velocity data during their descent phase in order to ensure safe, soft landing at the pre-designated sites. Data from the vehicle's Inertial Measurement Unit will not be sufficient due to significant drift error after extended travel time in space. Therefore, an onboard sensor is required to provide the necessary data for landing in the GPS-deprived environment of space. For this reason, NASA Langley Research Center has been developing an advanced Doppler lidar sensor capable of providing accurate and reliable data suitable for operation in the highly constrained environment of space. The Doppler lidar transmits three laser beams in different directions toward the ground. The signal from each beam provides the platform velocity and range to the ground along the laser line-of-sight (LOS). The six LOS measurements are then combined in order to determine the three components of the vehicle velocity vector, and to accurately measure altitude and attitude angles relative to the local ground. These measurements are used by an autonomous Guidance, Navigation, and Control system to accurately navigate the vehicle from a few kilometers above the ground to the designated location and to execute a gentle touchdown. A prototype version of our lidar sensor has been completed for a closed-loop demonstration onboard a rocket-powered terrestrial free-flyer vehicle.

  7. Doppler lidar sensor for precision navigation in GPS-deprived environment

    Amzajerdian, F.; Pierrottet, D. F.; Hines, G. D.; Petway, L. B.; Barnes, B. W.

    2013-05-01

    Landing mission concepts that are being developed for exploration of solar system bodies are increasingly ambitious in their implementations and objectives. Most of these missions require accurate position and velocity data during their descent phase in order to ensure safe, soft landing at the pre-designated sites. Data from the vehicle's Inertial Measurement Unit will not be sufficient due to significant drift error after extended travel time in space. Therefore, an onboard sensor is required to provide the necessary data for landing in the GPS-deprived environment of space. For this reason, NASA Langley Research Center has been developing an advanced Doppler lidar sensor capable of providing accurate and reliable data suitable for operation in the highly constrained environment of space. The Doppler lidar transmits three laser beams in different directions toward the ground. The signal from each beam provides the platform velocity and range to the ground along the laser line-of-sight (LOS). The six LOS measurements are then combined in order to determine the three components of the vehicle velocity vector, and to accurately measure altitude and attitude angles relative to the local ground. These measurements are used by an autonomous Guidance, Navigation, and Control system to accurately navigate the vehicle from a few kilometers above the ground to the designated location and to execute a gentle touchdown. A prototype version of our lidar sensor has been completed for a closed-loop demonstration onboard a rocket-powered terrestrial free-flyer vehicle.

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

    Lai-Chen, C.

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

  9. The Integration of GPR, GIS, and GPS for 3D Soil Morphologic Models

    Tischler, M.; Collins, M. E.

    2005-05-01

    Ground-Penetrating Radar (GPR) has become a useful and efficient instrument for gathering information about subsurface diagnostic horizons in Florida soils. Geographic Information Systems (GIS) are a popular and valuable tool for spatial data analysis of real world features in a digital environment. Ground-Penetrating Radar can be linked to GIS by using Global Positioning Systems (GPS). By combining GPR, GPS, and GIS technologies, a more detailed geophysical survey can be completed for an area of interest by integratinghydrologic, pedologic, and geologic data. Thus, the objectives of this research were to identify subsurface soil layers using GPR and their geographic position with a highly accurate GPS; to develop a procedure to import GPR data into a popular software package, such as ArcGIS, and; to create 3D subsurface models based on the imported GPR data. The site for this study was the Plant Science Research and Education Center in Marion County, Florida. The soils are characterized by Recent-Pleistocene-age sand over the clayey, marine deposited Plio-Miocene-age Hawthorn Formation which drapes the Eocene-age Ocala Limestone. Consequently, soils in the research area vary from deep quartz sands (Typic Quartzipsamments) to shallow outcrops of the Hawthorn Formation (Arenic Hapludalfs). A GPR survey was performed on a 160 m x 320 m grid to gather data for processing. Four subsurface models estimating the depth to argillic horizon were created using a variety of specialized GPR data filters and geostatistical data analyses. The models were compared with ground-truth points that measured the depth to argillic horizon to validate each model and calculate error metrics. These models may assist research station personnel to determine best management practices (including experimental plot placement, irrigation management, fertilizer treatment, and pesticide applications). In addition, the developed methodology exploits the potential of combining GPR and GIS.

  10. 38 CFR 4.46 - Accurate measurement.

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  11. Impact of Swarm GPS receiver updates on POD performance

    van den IJssel, Jose; Forte, Biagio; Montenbruck, Oliver

    2016-05-01

    The Swarm satellites are equipped with state-of-the-art Global Positioning System (GPS) receivers, which are used for the precise geolocation of the magnetic and electric field instruments, as well as for the determination of the Earth's gravity field, the total electron content and low-frequency thermospheric neutral densities. The onboard GPS receivers deliver high-quality data with an almost continuous data rate. However, the receivers show a slightly degraded performance when flying over the geomagnetic poles and the geomagnetic equator, due to ionospheric scintillation. Furthermore, with only eight channels available for dual-frequency tracking, the amount of collected GPS tracking data is relatively low compared with various other missions. Therefore, several modifications have been implemented to the Swarm GPS receivers. To optimise the amount of collected GPS data, the GPS antenna elevation mask has slowly been reduced from 10° to 2°. To improve the robustness against ionospheric scintillation, the bandwidths of the GPS receiver tracking loops have been widened. Because these modifications were first implemented on Swarm-C, their impact can be assessed by a comparison with the close flying Swarm-A satellite. This shows that both modifications have a positive impact on the GPS receiver performance. The reduced elevation mask increases the amount of GPS tracking data by more than 3 %, while the updated tracking loops lead to around 1.3 % more observations and a significant reduction in tracking losses due to severe equatorial scintillation. The additional observations at low elevation angles increase the average noise of the carrier phase observations, but nonetheless slightly improve the resulting reduced-dynamic and kinematic orbit accuracy as shown by independent satellite laser ranging (SLR) validation. The more robust tracking loops significantly reduce the large carrier phase observation errors at the geomagnetic poles and along the geomagnetic

  12. A comprehensive study on GPS-assisted aerial triangulation

    Ebadi, Hamid

    Aerial Triangulation (AT) has been used for mapping purposes for a long time to provide 3D coordinates of object points on the ground. This technique uses series of overlapping photographs, and some control points, in order to establish the relationship between the image coordinate system and object coordinate system. In the process of bundle block adjustment, image coordinate observations and coordinates of the ground control points are simultaneously adjusted and the exterior orientation parameters, as well as the ground coordinates of all tie and pass points, are estimated. One of the biggest challenges in AT is to reduce the number of control points. One effective way is to directly measure the exterior orientation parameters of the camera at the time of exposure. Airborne kinematic GPS (Global Positioning System) provides a means of determining the position of the aerial camera at each instant of exposure. The combined GPS-photogrammetric block adjustment takes advantage of weighted GPS observations, which significantly reduces the number of ground control points needed in a conventional block adjustment. A comprehensive software package, GAP (General Adjustment Program), was developed in this research to effectively integrate and adjust GPS, geodetic, and photogrammetric observations. Optimization of the GPS-photogrammetric bundle block adjustments for both simulated large scale mapping and real medium scale mapping was carried out. Aspects of reliability, and precision, as well as practical considerations, for an airborne GPS-photogrammetry system were also investigated. GPS coordinates of the camera exposure stations do not permit recovery of the roll angle of the aircraft in a GPS single strip triangulation. Therefore, ground control points are still required in addition to the GPS coordinates of exposure stations to overcome this problem, and to eliminate singularity of the normal matrix in the least squares adjustment. A new technique for GPS single

  13. Status of Precise Orbit Determination for Jason-2 Using GPS

    Melachroinos, S.; Lemoine, F. G.; Zelensky, N. P.; Rowlands, D. D.; Pavlis, D. E.

    2011-01-01

    The JASON-2 satellite, launched in June 2008, is the latest follow-on to the successful TOPEX/Poseidon (T/P) and JASON-I altimetry missions. JASON-2 is equipped with a TRSR Blackjack GPS dual-frequency receiver, a laser retroreflector array, and a DORIS receiver for precise orbit determination (POD). The most recent time series of orbits computed at NASA GSFC, based on SLR/DORIS data have been completed using both ITRF2005 and ITRF2008. These orbits have been shown to agree radially at 1 cm RMS for dynamic vs SLRlDORIS reduced-dynamic orbits and in comparison with orbits produced by other analysis centers (Lemoine et al., 2010; Zelensky et al., 2010; Cerri et al., 2010). We have recently upgraded the GEODYN software to implement model improvements for GPS processing. We describe the implementation of IGS standards to the Jason2 GEODYN GPS processing, and other dynamical and measurement model improvements. Our GPS-only JASON-2 orbit accuracy is assessed using a number of tests including analysis of independent SLR and altimeter crossover residuals, orbit overlap differences, and direct comparison to orbits generated at GSFC using SLR and DORIS tracking, and to orbits generated externally at other centers. Tests based on SLR and the altimeter crossover residuals provide the best performance indicator for independent validation of the NASAlGSFC GPS-only reduced dynamic orbits. For the ITRF2005 and ITRF2008 implementation of our GPS-only obits we are using the IGS05 and IGS08 standards. Reduced dynamic versus dynamic orbit differences are used to characterize the remaining force model error and TRF instability. We evaluate the GPS vs SLR & DORIS orbits produced using the GEODYN software and assess in particular their consistency radially and the stability of the altimeter satellite reference frame in the Z direction for both ITRF2005 and ITRF2008 as a proxy to assess the consistency of the reference frame for altimeter satellite POD.

  14. Precise orbit determination and point positioning using GPS, Glonass, Galileo and BeiDou

    Tegedor J.

    2014-04-01

    Full Text Available State of the art Precise Point Positioning (PPP is currently based on dual-frequency processing of GPS and Glonass navigation systems. The International GNSS Service (IGS is routinely providing the most accurate orbit and clock products for these constellations, allowing point positioning at centimeter-level accuracy. At the same time, the GNSS landscape is evolving rapidly, with the deployment of new constellations, such as Galileo and BeiDou. The BeiDou constellation currently consists of 14 operational satellites, and the 4 Galileo In-Orbit Validation (IOV satellites are transmitting initial Galileo signals. This paper focuses on the integration of Galileo and BeiDou in PPP, together with GPS and Glonass. Satellite orbits and clocks for all constellations are generated using a network adjustment with observation data collected by the IGS Multi-GNSS Experiment (MGEX, as well as from Fugro proprietary reference station network. The orbit processing strategy is described, and orbit accuracy for Galileo and BeiDou is assessed via orbit overlaps, for different arc lengths. Kinematic post-processed multi-GNSS positioning results are presented. The benefits of multiconstellation PPP are discussed in terms of enhanced availability and positioning accuracy.

  15. Forest operations planning by using RTK-GPS based digital elevation model

    Neşe Gülci

    2015-07-01

    Full Text Available Having large proportion of forests in mountainous terrain in Turkey, the logging methods that not only minimize operational costs but also minimize environmental damages should be determined in forest operations planning. In a case where necessary logging equipment and machines are available, ground slope is the most important factor in determining the logging method. For this reason, accurate, up to date, and precise ground slope data is very crucial in the success of forest operations planning. In recent years, high-resolution Digital Elevation Models (DEM can be generated for forested areas by using Real Time Kinematic (RTK GPS method and these DEMs can be used to develop precise slope maps. In this study, high-resolution DEM was developed by RTK-GPS method to generate precise slope map in a sample area. Then, the slope map was classified into slope classes specified by IUFRO in order to assist forest operations planning. According to the results, logging methods that are suitable for very steep and steep terrain conditions (i.e. skyline logging, cable pulling, and chute systems should be preferred in 48.1% of the study area. It was also found that logging methods that are suitable for terrain with medium slope (i.e. skidding and cable pulling and gentle slope (i.e. skidding and mobile winch should be preferred in 34.1% and 17.8% of the study area, respectively.

  16. IVS Tropospheric Parameters: Comparison with DORIS and GPS for CONT02

    Schuh, Harald; Snajdrova, Kristyna; Boehm, Johannes; Willis, Pascal; Engelhardt, Gerald; Lanotte, Roberto; Tomasi, Paolo; Negusini, Monia; MacMillan, Daniel; Vereshchagina, Iraida

    2004-01-01

    In April 2002 the IVS (International VLBI Service for Geodesy and Astrometry) set up the Pilot Project - Tropospheric Parameters, and the Institute of Geodesy and Geophysics (IGG), Vienna, was put in charge of coordinating the project. Seven IVS Analysis Centers have joined the project and regularly submitted their estimates of tropospheric parameters (wet and total zenith delays, horizontal gradients) for all IVS-R1 mid IVS-R4 sessions since January 1st, 2002. The individual submissions are combined by a two-step procedure to obtain stable, robust and highly accurate tropospheric parameter time series with one hour resolution (internal accuracy: 2-4 ram). Starting with July 2003, the combined tropospheric estimates became operational IVS products. In the second half of October 2002 the VLBI campaign CONT02 was observed with 8 stations participating around the globe. At four of them (Gilmore Creek, U.S.A.; Hartebeesthoek, South Africa; Kokee Park, U.S.A.; Ny-Alesund, Norway) also total zenith delays from DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite) are available and these estimates are compared with those from the IGS (International GPS Service) and the IVS. The distance from the DORIS beacons to the co-located GPS and VLBI stations is around 2 km or less for the four sites mentioned above.

  17. Error modeling for differential GPS. M.S. Thesis - MIT, 12 May 1995

    Blerman, Gregory S.

    1995-01-01

    Differential Global Positioning System (DGPS) positioning is used to accurately locate a GPS receiver based upon the well-known position of a reference site. In utilizing this technique, several error sources contribute to position inaccuracy. This thesis investigates the error in DGPS operation and attempts to develop a statistical model for the behavior of this error. The model for DGPS error is developed using GPS data collected by Draper Laboratory. The Marquardt method for nonlinear curve-fitting is used to find the parameters of a first order Markov process that models the average errors from the collected data. The results show that a first order Markov process can be used to model the DGPS error as a function of baseline distance and time delay. The model's time correlation constant is 3847.1 seconds (1.07 hours) for the mean square error. The distance correlation constant is 122.8 kilometers. The total process variance for the DGPS model is 3.73 sq meters.

  18. Evaluation of Experimental Data from the GAINS Balloon GPS Surface Reflection Instrument

    Gance, George G.; Johnson, Thomas A.

    2004-01-01

    The GPS Surface Reflection Instrument was integrated as an experiment on the GAINS (Global Airocean IN-situ System) 48-hour balloon mission flown in September 2001. The data collected by similar instruments in the past has been used to measure sea state from which ocean surface winds can be accurately estimated. The GPS signal has also been shown to be reflected from wetland areas and even from subsurface moisture. The current version of the instrument has been redesigned to be more compact, use less power, and withstand a greater variation in environmental conditions than previous versions. This instrument has also incorporated a new data collection mode to track 5 direct satellites (providing a continuous navigation solution) and multiplex the remaining 7 channels to track the reflected signal of the satellite tracked in channel 0. The new software mode has been shown to increase the signal to noise ratio of the collected data and enhance the science return of the instrument. During the 48-hour flight over the Northwest US, the instrument will measure surface reflections that can be detected over the balloon's ground track. Since ground surface elevations in this area vary widely from the WGS-84 ellipsoid altitude, the instrument software has been modified to incorporate a surface altitude correction based on USGS 30-minute Digital Elevation Models. Information presented will include facts about instrument design goals, data collection methodologies and algorithms, and results of the science data analyses for the 48-hour mission.

  19. Active landslide monitoring using remote sensing data, GPS measurements and cameras on board UAV

    Nikolakopoulos, Konstantinos G.; Kavoura, Katerina; Depountis, Nikolaos; Argyropoulos, Nikolaos; Koukouvelas, Ioannis; Sabatakakis, Nikolaos

    2015-10-01

    An active landslide can be monitored using many different methods: Classical geotechnical measurements like inclinometer, topographical survey measurements with total stations or GPS and photogrammetric techniques using airphotos or high resolution satellite images. As the cost of the aerial photo campaign and the acquisition of very high resolution satellite data is quite expensive the use of cameras on board UAV could be an identical solution. Small UAVs (Unmanned Aerial Vehicles) have started their development as expensive toys but they currently became a very valuable tool in remote sensing monitoring of small areas. The purpose of this work is to demonstrate a cheap but effective solution for an active landslide monitoring. We present the first experimental results of the synergistic use of UAV, GPS measurements and remote sensing data. A six-rotor aircraft with a total weight of 6 kg carrying two small cameras has been used. Very accurate digital airphotos, high accuracy DSM, DGPS measurements and the data captured from the UAV are combined and the results are presented in the current study.

  20. Digital image georeferencing from a multiple camera system by GPS/INS

    Mostafa, Mohamed M. R.; Schwarz, Klaus-Peter

    In this paper, the development and testing of an airborne fully digital multi-sensor system for digital mapping data acquisition is presented. The system acquires two streams of data, namely, navigation (georeferencing) data and imaging data. The navigation data are obtained by integrating an accurate strapdown inertial navigation system with a differential GPS system (DGPS). The imaging data are acquired by two low-cost digital cameras, configured in such a way so as to reduce their geometric limitations. The two cameras capture strips of overlapping nadir and oblique images. The GPS/INS-derived trajectory contains the full translational and rotational motion of the carrier aircraft. Thus, image exterior orientation information is extracted from the trajectory, during post-processing. This approach eliminates the need for ground control (GCP) when computing 3D positions of objects that appear in the field of view of the system imaging component. Two approaches for calibrating the system are presented, namely, terrestrial calibration and in-flight calibration. Test flights were conducted over the campus of The University of Calgary. Testing the system showed that best ground point positioning accuracy at 1:12,000 average image scale is 0.2 m (RMS) in easting and northing and 0.3 m (RMS) in height. Preliminary results indicate that major applications of such a system in the future are in the field of digital mapping, at scales of 1:5000 and smaller, and in the generation of digital elevation models for engineering applications.

  1. Sequential Quadratic Method for GPS NLOS Positioning in Urban Canyon Envi-ronments

    He-Sheng Wang

    2013-03-01

    Full Text Available In this paper, the problem of GPS non-line-of-sight (NLOS positioning in urban canyon environment is considered. We propose a new position-determination estimator based on the sequential quadratic programming (SQP that is able to estimate and eliminate the path-delay error caused by the indirect transmission of the GPS signal. The estimator takes into account the measurement bias resulting from NLOS transmission, and in the mean-time also improves the location accuracy of a satellite positioning system. The present method can effectively eliminate the NLOS delay errors and is also able to improve the location accuracy of a satellite navigation receiver in an urban canyon environment. A Wilcoxon-norm-based regressor is further derived to improve the probability of detection of the NLOS biases. The Wilcoxon regressor is a robust estimator that is well suitable for identifying outliers (in our case, the NLOS biases during the regression process. In our experimental results, it is demonstrated that the proposed estimator can compute the coordinate of a user location in an accurate fashion after identifying and removing the measurement biases.

  2. The use of civilian-type GPS receivers by the military and their vulnerability to jamming

    Ludwig Combrinck

    2012-05-01

    Full Text Available We considered the impact of external influences on a GPS receiver and how these influences affect the capabilities of civilian-type GPS receivers. A standard commercial radio frequency signal generator and passive GPS antenna were used to test the sensitivity of GPS to intentional jamming; the possible effects of the terrain on the propagation of the jamming signal were also tested. It was found that the high sensitivity of GPS receivers and the low strength level of GPS satellite signals combine to make GPS receivers very vulnerable to intentional jamming or unintentional radio frequency interference. Terrain undulation was used to shield GPS antennas from the direct line-of-sight of the jamming antenna and this indicated that terrain characteristics can be used to mitigate the effects of jamming. These results illuminate the vulnerability of civilian-type GPS receivers to the possibility and the ease of disablement and establish the foundation for future work.

  3. Earth tide effects on kinematic/static GPS positioning in Denmark and Greenland

    Xu, G.C.; Knudsen, Per

    2000-01-01

    demonstrating that the Earth tide effects can be viewed by GPS surveying. They are given through static GPS data static processing, static GPS data kinematic processing, and airborne kinematic GPS data processing. In these cases, the Earth tide effects can be subtracted from the GPS results. The determination......A detailed Study of the Earth tide effects on the GPS kinematic/static positioning is presented in this paper by using theoretical Earth tide computation and practical GPS data processing. Tidal effects could reach up to 30 cm in Denmark and Greenland depending on the measuring time and the...... position of reference station. With a baseline less than 80 km, the difference of the Earth tide effects could reach more than 5 mm. So, in precise applications of GPS positioning, the Earth tide effect has to be taken into account even for a relative small local GPS network. Several examples are given for...

  4. GPS assisted helicopter photogrammetry for highway profiling

    Joy, Christopher Iain Harold

    1998-01-01

    Roads are an integral part of today's lifestyle. Indeed, a modern and efficient economy requires a satisfactory road network. The road network in the United Kingdom faces ever-increasing demands with 94% of passenger travel and 92% of freight transport undertaken by road. Maintenance of the network is essential. Prior to the commencement of any maintenance scheme, an accurate highway profile is measured by undertaking a detailed topographic survey of the road surface and the adjacent verges. ...

  5. New GPS Constraints On Owens Valley Fault Slip Rates

    Jha, S.; Hammond, W. C.; Kreemer, C. W.; Blewitt, G.

    2009-12-01

    The Owens Valley fault (OVF) is one of several north- to northwest-striking faults that collectively accommodate ~10 mm/yr of dextral shear and extension across the southern Walker Lane/Eastern California Shear Zone (SWL). This zone, which lies east of the San Andreas Fault system and the Sierra Nevada microplate and north of the Garlock Fault, accommodates 20-25% of the Pacific/North America relative plate motion. The OVF strikes subparallel to principal regional faults to the east, including the Panamint Valley, Death Valley, and Fish Lake Valley fault zones, and is the site of an M 7.5 earthquake in 1872. Fault slip rates are a key input into seismic hazard modeling and can be estimated from GPS measurements that quantify the rate and pattern of interseismic crustal deformation. Earlier geodetic estimates based on campaign GPS are between ~2-8.5 mm/yr, while geologic estimates range from ~1 to 4 mm/yr. In the past several years, GPS constraints on crustal deformation of the SWL has improved though the southward extension of the MAGNET GPS network with 3 campaigns extending the time series to 4 years from 2005 to 2009, installation of EarthScope Plate Boundary Observatory, and longer time series on stations of the Basin and Range GPS network. These data have been analyzed using GIPSY-OASIS II with recently reprocessed orbits from the IGS analysis center at JPL. Our GPS processing now includes satellite and station antenna calibrations, random-walk tropospheric zenith delay and gradients using the GMF mapping function, second-order ionospheric corrections, global-scale ambiguity resolution using our custom Ambizap software, and our custom Great Basin spatially-filtered reference frame. These improved measurements justify a new look at rates across the OVF. We present a revised estimate for the slip rate by applying a block modeling methodology constrained by the new GPS data. Since the GPS data in this region are suspected to contain transient signals from post

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

    Schöne, T.; Pandoe, W.; Mudita, I.; Roemer, S.; Illigner, J.; Zech, C.; Galas, R.

    2011-03-01

    On Boxing Day 2004, a severe tsunami was generated by a strong earthquake in Northern Sumatra causing a large number of casualties. At this time, neither an offshore buoy network was in place to measure tsunami waves, nor a system to disseminate tsunami warnings to local governmental entities. Since then, buoys have been developed by Indonesia and Germany, complemented by NOAA's Deep-ocean Assessment and Reporting of Tsunamis (DART) buoys, and have been moored offshore Sumatra and Java. The suite of sensors for offshore tsunami detection in Indonesia has been advanced by adding GPS technology for water level measurements. The usage of GPS buoys in tsunami warning systems is a relatively new approach. The concept of the German Indonesian Tsunami Early Warning System (GITEWS) (Rudloff et al., 2009) combines GPS technology and ocean bottom pressure (OBP) measurements. Especially for near-field installations where the seismic noise may deteriorate the OBP data, GPS-derived sea level heights provide additional information. The GPS buoy technology is precise enough to detect medium to large tsunamis of amplitudes larger than 10 cm. The analysis presented here suggests that for about 68% of the time, tsunamis larger than 5 cm may be detectable.

  7. GPS Technology and Human Psychological Research: A Methodological Proposal

    Pedro S. A. Wolf

    2010-10-01

    Full Text Available Animal behaviorists have made extensive use of GPS technology since 1991. In contrast, psychological research has made little use of the technology, even though the technology is relatively inexpensive, familiar, and widespread. Hence, its potential for pure and applied psychological research remains untapped. We describe three methods psychologists could apply to individual differences research, clinical research, or spatial use research. In the context of individual differences research, GPS technology permits us to test hypotheses predicting specific relations among patterns of spatial use and individual differences variables. In a clinical context, GPS technology provides outcome measures that may relate to the outcome of interventions designed to treat psychological disorders that, for example, may leave a person homebound (e.g. Agoraphobia, PTSD, TBI. Finally, GPS technology provides natural measures of spatial use. We, for example, used GPS technology to quantify traffic flow and exhibit use at the Arizona Sonora Desert Museum. Interested parties could easily extend this methodology some aspects of urban planning or business usage.DOI: 10.2458/azu_jmmss.v1i1.74

  8. GPS/INS Integration: A Performance Sensitivity Analysis

    Wang Jin-ling; H. K. Lee; C. Rizos

    2003-01-01

    Inertial Navigation System (INS) and Global Positioning System (GPS) technologies have been widely used in a variety of positioning and navigation applications. Both systems have their unique features and shortcomings. Therefore, the integration of GPS with INS is now critical to overcome each of their drawbacks and to maximize each of their benefits. The integration of GPS with INS can be implemented using a Kalman filter in such modes as loosely, tightly and ultra-tightly coupled. In all these integration modes the INS error states, together with any navigation state (position, velocity, attitude) and other unknown parameters of interest, are estimated using GPS measurements. In a high performance system it is expected that all these unknown states will be precisely estimated. Although it has been noted that both the quality of the GPS measurements and the trajectory and/or manoeuvre characteristics of the problem will have impacts on system performance, a systematic sensitivity analysis is still lacking. This paper will address this issue through real data analyses. The performance analysisresults are very relevant to system design and platform trajectory and/or manoeuvre optimisation.

  9. Ethics support for GPs: what should it look like?

    Clark-Grill, Monika

    2016-03-01

    INTRODUCTION Ethics support services for hospital clinicians have become increasingly common globally but not as yet in New Zealand. However, an initiative to change this is gathering momentum. Its slogan 'Clinical ethics is everyone's business' indicates that the aim is to encompass all of health care, not just the hospital sector. General Practitioners (GPs) deal with ethical issues on a daily basis. These issues are often quite different from ethical issues in hospitals. To make future ethics support relevant for primary care, local GPs were interviewed to find out how they might envisage ethics support services that could be useful to them. METHODS A focus group interview with six GPs and semi-structured individual interviews with three GPs were conducted. Questions included how they made decisions on ethical issues at present, what they perceived as obstacles to ethical reflection and decision-making, and what support might be helpful. FINDINGS Three areas of ethics support were considered potentially useful: Formal ethics education during GP training, access to an ethicist for assistance with analysing an ethical issue, and professional guidance with structured ethics conversations in peer groups. CONCLUSION The complex nature of general practice requires GPs to be well educated and supported for handling ethical issues. The findings from this study could serve as input to the development of ethics support services. KEYWORDS General practice; primary care; ethics; support; education. PMID:27477378

  10. The impact of temporal geopotential variations on GPS

    Melachroinos, S.; Lemoine, F. G.; Zelensky, N. P.; Beckley, B. D.; Chinn, D. S.; Nicholas, J. B.; McCarthy, J. J.; Pennington, T.; Luthcke, S. B.

    2012-12-01

    Lemoine et al. (2006) and Lemoine et al. (2010) showed that applying more detailed models of time-variable gravity (TVG) improved the quality of the altimeter satellite orbits (e.g. TOPEX/Poseidon, Jason-1, Jason-2). This modeling include application of atmospheric gravity derived from 6-hrly pressure fields obtained from the ECMWF and annual gravity variations to degree & order 20x20 in spherical harmonics derived from GRACE data. This approach allowed the development of a consistent geophysical model for application to altimeter satellite orbit determination from 1993 to 2011. In addition, we have also evaluated the impact of TVG modeling on the POD of Jason-1 and Jason-2 by application of a weekly degree & order four gravity coefficient time series developed using data from ten SLR & DORIS-tracked satellites from 1993 to 2011 (Lemoine et al., 2011). In this study we first evaluate the impact of a more detailed TVG modeling to the GPS constellation orbits and positions of a dedicated IGb08 GPS core station network used for the Jason-1 and Jason-2 POD. Using the NASA GSFC GEODYN orbit determination software, for the computation of the GPS constellation orbits we use a consistent LEO-to-ground GPS station approach with Jason-1 and Jason-2. Then subsequently we re-estimate the GPS ground station orbits.

  11. Can RTK GPS be Used to Improve Cadastral Infrastructure?

    Craig Roberts

    2011-01-01

    Full Text Available Cadastral surveying is concerned with the process of gathering evidence in the form of position information that is used to define the location of objects or land boundaries for the purposes of identifying ownership and/or the value of land parcels. The advent of Global Navigation Satellite Systems (GNSS, such as the Global Positioning System (GPS, has revolutionised the way 3-dimensional positions are determined and GPS surveying techniques, particularly Real Time Kinematic (RTK, are increasingly being adopted by cadastral surveyors. This paper presents a methodology for using RTK GPS observations to improve the existing cadastral survey control infrastructure, based on an extensive survey carried out in New South Wales, Australia. It is shown that accuracies (RMS of 11 mm in the horizontal and 34 mm in the vertical component (1? can be achieved for this dataset. Calculated bearings and distances agree very well with the official values derived from the state’s survey control database, easily meeting accuracy specifications and survey regulation requirements. 55% of the unestablished marks surveyed were able to be upgraded to cadastral survey control quality. Enhancements in the GPS survey design would have enabled an even higher percentage of marks to be classified as established, showing that the RTK GPS technique is well suited to improving survey control infrastructure for cadastral surveyors.

  12. Initial observations of ULF waves using GPS TEC

    Complete text of publication follows. The increased number of GPS receivers capable of observing Total Electron Content (TEC) that are deployed under the high-latitude ionosphere provides a new opportunity to observe ULF waves. In particular, these new observations may provide a significant benefit when combined with the traditionally available, though spatially-integrated, signal from ground-based magnetometers. We will present direct comparisons of ULF pulsations observed with ground magnetometers, the SuperDARN radars, and GPS TEC. Initial indications are that for Pc5 waves of nominal amplitude observed on the ground, there exists a clear signal in the local GPS TEC observations. In some cases the density and distribution of the GPS receivers allows for the study of spatial distribution of these fluctuations in the ionosphere on scales that are smaller than the spatial-integration scale of a ground-based magnetometer. Additionally, in some regions the network of GPS receivers provides far better spatial coverage on larger spatial scales than the existing network of magnetometers.

  13. Data Analysis of Permanent GPS Sites (RING) in Italy

    Serpelloni, E.; Cavaliere, A.; Pietrantonio, G.; Galvani, A.; Esposito, A.; Sepe, V.; Devoti, R.; Riguzzi, F.

    2007-12-01

    The RING (Rete Integrata Nazionale GPS) GPS network is the result of a scientific project started by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) in 2004 with the aim of increasing the number of continuous GPS stations (CGPS) in Italy in order to improve the knowledge of the geodynamics and tectonic processes acting in this area which is characterized by a complex set of independent or partially independent crustal blocks, within the slowly converging African and Eurasian plates. At present RING is a dense CGPS network of more than 110 stations covering the Italian area and integrating GPS receivers with broad-band seismometers and accelerometers in real time connection with three acquisition centers. In this work we describe the data analysis strategy of the whole GPS network (consisting of RING sites, other public Italian CGPS and some IGS sites for a total amount of about 300 stations) and some results in terms of position time series and velocities. The processing is performed adopting a distributed session approach, with more than 10 clusters, sharing common stations, each of them consisting of about 40 stations. Daily loosely constrained solutions are routinely produced for each cluster using the Bernese and Gamit softwares and then transformed into the ITRF05 reference frame. In the next months these solutions will be freely available as daily SINEX files on the public RING website http://ring.gm.ingv.it and subsequently other derived geodetic products (full time series, velocity field, etc.) will also be available.

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

    T. Schöne

    2011-03-01

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

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

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

  15. Impacts of Stochastic Modeling on GPS-derived ZTD Estimations

    Jin, Shuanggen

    2010-01-01

    GPS-derived ZTD (Zenith Tropospheric Delay) plays a key role in near real-time weather forecasting, especially in improving the precision of Numerical Weather Prediction (NWP) models. The ZTD is usually estimated using the first-order Gauss-Markov process with a fairly large correlation, and under the assumption that all the GPS measurements, carrier phases or pseudo-ranges, have the same accuracy. However, these assumptions are unrealistic. This paper aims to investigate the impact of several stochastic modeling methods on GPS-derived ZTD estimations using Australian IGS data. The results show that the accuracy of GPS-derived ZTD can be improved using a suitable stochastic model for the GPS measurements. The stochastic model using satellite elevation angle-based cosine function is better than other investigated stochastic models. It is noted that, when different stochastic modeling strategies are used, the variations in estimated ZTD can reach as much as 1cm. This improvement of ZTD estimation is certainly c...

  16. Distributed pedestrian detection alerts based on data fusion with accurate localization.

    García, Fernando; Jiménez, Felipe; Anaya, José Javier; Armingol, José María; Naranjo, José Eugenio; de la Escalera, Arturo

    2013-01-01

    Among Advanced Driver Assistance Systems (ADAS) pedestrian detection is a common issue due to the vulnerability of pedestrians in the event of accidents. In the present work, a novel approach for pedestrian detection based on data fusion is presented. Data fusion helps to overcome the limitations inherent to each detection system (computer vision and laser scanner) and provides accurate and trustable tracking of any pedestrian movement. The application is complemented by an efficient communication protocol, able to alert vehicles in the surroundings by a fast and reliable communication. The combination of a powerful location, based on a GPS with inertial measurement, and accurate obstacle localization based on data fusion has allowed locating the detected pedestrians with high accuracy. Tests proved the viability of the detection system and the efficiency of the communication, even at long distances. By the use of the alert communication, dangerous situations such as occlusions or misdetections can be avoided. PMID:24008284

  17. Distributed Pedestrian Detection Alerts Based on Data Fusion with Accurate Localization

    Arturo de la Escalera

    2013-09-01

    Full Text Available Among Advanced Driver Assistance Systems (ADAS pedestrian detection is a common issue due to the vulnerability of pedestrians in the event of accidents. In the present work, a novel approach for pedestrian detection based on data fusion is presented. Data fusion helps to overcome the limitations inherent to each detection system (computer vision and laser scanner and provides accurate and trustable tracking of any pedestrian movement. The application is complemented by an efficient communication protocol, able to alert vehicles in the surroundings by a fast and reliable communication. The combination of a powerful location, based on a GPS with inertial measurement, and accurate obstacle localization based on data fusion has allowed locating the detected pedestrians with high accuracy. Tests proved the viability of the detection system and the efficiency of the communication, even at long distances. By the use of the alert communication, dangerous situations such as occlusions or misdetections can be avoided.

  18. Distributed Pedestrian Detection Alerts Based on Data Fusion with Accurate Localization

    García, Fernando; Jiménez, Felipe; Anaya, José Javier; Armingol, José María; Naranjo, José Eugenio; de la Escalera, Arturo

    2013-01-01

    Among Advanced Driver Assistance Systems (ADAS) pedestrian detection is a common issue due to the vulnerability of pedestrians in the event of accidents. In the present work, a novel approach for pedestrian detection based on data fusion is presented. Data fusion helps to overcome the limitations inherent to each detection system (computer vision and laser scanner) and provides accurate and trustable tracking of any pedestrian movement. The application is complemented by an efficient communication protocol, able to alert vehicles in the surroundings by a fast and reliable communication. The combination of a powerful location, based on a GPS with inertial measurement, and accurate obstacle localization based on data fusion has allowed locating the detected pedestrians with high accuracy. Tests proved the viability of the detection system and the efficiency of the communication, even at long distances. By the use of the alert communication, dangerous situations such as occlusions or misdetections can be avoided. PMID:24008284

  19. ACCURACY ASSESSMENT OF COMBINED GPS/GALILEO SINGLE POINT POSITIONING%GPS/GALILEO组合单点定位精度分析

    罗小敏; 蔡昌盛

    2013-01-01

    建立了GPS/GALILEO组合单点定位的数学模型,在对各项误差改正的基础上,利用全球多卫星导航系统试验网跟踪站的观测数据,对GPS/GALILEO组合单点定位模型进行了试算.结果表明,当GPS观测卫星较充足时,增加1~2颗GALILEO观测卫星并不能有效地提高组合GPS/GALILEO定位的精度,当GPS观测卫星较少时,组合GPS/GALILEO系统相比单GPS系统,定位精度有较明显的改善.%A mathematic model of combined GPS/GALILEO single point positioning (SPP) is developed.On the basis of error corrections,the combined GPS/GALILEO SPP model is tested using the data of the MGEX tracking stations.The results indicate that the accuracy of the GPS/GALILEO SPP is not significantly improved when adding only one or two GALILEO satellites when the GPS observation satellites are sufficient.However,in the condition of insufficient number of GPS satellites,the accuracy of the combined GPS/GALILEO SPP is better than the GPS-onlv SPP.

  20. Evaluation and application of GPS and altimetry data over central Dronning Maud Land, Antarctica: annualelevation change, a digital elevation model, and surface flow velocity

    Wesche, Christine

    2009-01-01

    The polar ice sheets are unique paleoclimatic archives and play an important role in recent and future climate. The melting of the big freshwater reservoirs will not only increase the global sea level, but will also influence the ocean currents. Therefore, it will be of particular interest to improve the currently available numeric climate models to achieve more accurate statements about climatic change and its consequences. In this work, the evaluation and the different applications of GPS a...

  1. Performance Assessment of GPS-Sensed Precipitable Water Vapor using IGS Ultra-Rapid Orbits: A Preliminary Study in Thailand

    Yoon-Soo Choi

    2011-01-01

    Full Text Available Precipitable Water Vapor (PWV is a significant variable used for climate change studies. Currently PWV can be derived from the Global Positioning System (GPS observation in addition to the specific instruments such as Radiosondes (RS, Microwave Radiometers (MWR and Meteorological Satellites. To accurately derive PWV from GPS data, long periods of observation time in conjunction with final orbit data have to be applied in the data processing steps. This final orbit data can be acquired from the International GNSS Service (IGS with 13 days latency, which is not practical in climate change studies or meteorological forecasting. Alternatively, real-time ultra-rapid orbits are more suitable for this application but with lower orbit accuracy. It is therefore interesting to evaluate the impact of using different orbits in the estimation of PWV. In this study, data from permanent GPS base stations in Thailand were processed using Bernese 5.0 software to derive near real-time PWV values. Ultra-rapid orbit data have been introduced in the data processing step with different time windows and compared to that using final orbit data with the 24-hr time window. The results have shown that 1.0 mm and 2.9 mm biases can be achieved using 24-hr and 12-hr time windows, respectively. These results therefore address the potential use of ultra-rapid orbits for a near real-time estimation of PWV.

  2. GPS Zenith Total Delays and Precipitable Water in comparison with special meteorological observations in Verona (Italyduring MAP-SOP

    S. Corradini

    2002-06-01

    Full Text Available Continuous meteorological examination of the Pre-Alpine zones in Northern Italy (Po Valleyis important for determination of atmospheric water cycles connected with floods and rainfalls.During a special meteorological observing period (MAP-SOP,radiosounding and other measurements were made in the site of Verona (Italy. This paper deals with Zenith Total Delay (ZTDand Precipitable Water (PWcomparisons obtained by GPS, radiosounding and other meteorological measurements.PW and ZTD from ground-based GPS data in comparisonwith classical techniques (e.g.,WVR,radiosoundingfrom recent literature present an accurate tool for use in meteorology applications (e.g.,assimilation in Numerical Weather Prediction (NWPmodels on short-range precipitation forecasts.Comparison of such ZTD for MAP-SOP showed a standard deviation of 16.1 mm and PW comparison showed a standard deviation of 2.7 mm,confirming the accuracy of GPS measurements for meteorology applications.In addition,PW data and its time variation are also matched with time series of meteorological situations.Those results indicate that changes in PW values could be connected to changes in air masses,i.e.to passages of both cold and warm fronts.There is also a correlation between precipitation, forthcoming increase and the following decrease of PW.A good agreement between oscillation of PW and precipitation and strong cyclonic activities is found.

  3. SAR Inteferometry and GPS Surveying for Subsidence Monitoring and its Contribution to Risk Management, the Case Study of Aguascalientes, Mexico

    Esquivel, R.; Castaneda, L. P.

    2013-05-01

    Aguascalientes valley is just one of many regions affected by ground subsidence in Mexico, results of GPS monitoring from 2003 to date and differential SAR interferometry using Envisat archived data show subsidence maximums of 15 centimeters but with a decreasing rate with time. Recent implementation of TerraSAR-X stripmap mode images allowed a more accurate estimation of displacements, which are being used for subsidence mapping and to develop models for corrections to geodetic positions. In addition, results of the study are also being used to the development of the State's atlas of hazards and will contribute by detecting new ground failures and areas susceptible to failure.

  4. Pembuatan Digital Elevation Model Resolusi 10m dari Peta RBI dan Survei GPS dengan Algoritma Anudem

    Indarto

    2014-04-01

    Full Text Available This study proposes the generation of Digital Elevation Model (DEM with spatial resolution of 10m x 10m by re-interpolation of elevation data. Data input for this study includes: (1 digitized datum coordinate from RBI map, (2 sample points surveyed by GPS, (3 digitized contour data fromSRTM DEM and ASTER GDEM2, and (4 digitized stream-network layer from RBI. All collected data were converted to mass point coordinats. On the top of Topogrid-ArcGIS, all points data were interpolated to produce DEM. After that the produced DEM were compared and evaluated to the SRTM and ASTER DEMvisually. The result shows that produced DEM are more accurate to represent the detailed topography of the study areas.

  5. Reanalysis of CORS and Global GPS Data at the National Geodetic Survey

    Rohde, J. R.; Ngs Gps Reanalysis Team

    2010-12-01

    The National Geodetic Survey (NGS) has reprocessed the full history of Global Positioning System (GPS) data colledted from 1994.0 to 2010.5 for a subset of stations of the International GNSS Service (IGS) global tracking network and for stations of the U.S. Continuously Operating Reference Stations (CORS) network managed by NGS. This reprocessing effort focused on using the latest models and methodologies to accurately determine regularized positions and secular velocities for CORS relative to the International Reference Frame of 2008 (ITRF2008) and the North American Datum of 1983 (NAD83). We present a summary of the strategy for determining the stations' positions and velocities relative to ITRF2008, a discussion of the issues involved in transforming the stations' positions and velocities from ITRF2008 to NAD83, and a general discussion of the updated CORS velocity field.

  6. Airborne Digital Sensor System and GPS-aided inertial technology for direct geopositioning in rough terrain

    Sanchez, Richard D.

    2004-01-01

    High-resolution airborne digital cameras with onboard data collection based on the Global Positioning System (GPS) and inertial navigation systems (INS) technology may offer a real-time means to gather accurate topographic map information by reducing ground control and eliminating aerial triangulation. Past evaluations of this integrated system over relatively flat terrain have proven successful. The author uses Emerge Digital Sensor System (DSS) combined with Applanix Corporation?s Position and Orientation Solutions for Direct Georeferencing to examine the positional mapping accuracy in rough terrain. The positional accuracy documented in this study did not meet large-scale mapping requirements owing to an apparent system mechanical failure. Nonetheless, the findings yield important information on a new approach for mapping in Antarctica and other remote or inaccessible areas of the world.

  7. A New GPS-based Digital Protection System for Smart Grids in Loop Structure

    X. Liu

    2014-12-01

    Full Text Available This paper presents a new digital protection system to solve the protection challenges in future smart grids, i.e., fast protection and fault isolation in a loop-structured system with limited magnitude of fault current. The new system combines two protection algorithms, i.e., a differential protection as the primary algorithm and an overcurrent protection as the backup one. The new system uses real-time Ethernet and digital data acquisition techniques to overcome the restriction on data transmission over large grids. The current measurements at different locations are time-synchronized by GPS clocks, and then transmitted to a central computer via the Ethernet. As opposed to digital relays which often contain PMU functionality nowadays, this approach uses time stamps on the instantaneous current values. We build a prototype of the new system on a test-bed. The results from simulations and experiments have demonstrated that the protection system achieves fast and accurate protection.

  8. RELIABILITY AND ACCURACY OF 10 HZ GPS DEVICES FOR SHORT-DISTANCE EXERCISE

    Julen Castellano

    2011-03-01

    Full Text Available The use of GPS technology for training and research purposes requires a study of the reliability, validity and accuracy of the data generated (Petersen et al., 2009. To date, studies have focused on devices with a logging rate of 1 Hz and 5 Hz (Coutts and Duffield, 2010; Duffield et al., 2010; Jennings et al., 2010; MacLeod et al., 2009; Petersen et al., 2009; Portas et al., 2010, although it seems that more frequent sampling can increase the accuracy of the information provided by these devices (Jennings et al., 2010; MacLeod et al., 2009, Portas et al., 2010. However, we are unaware of any study of the reliability and accuracy of GPS devices using a sampling frequency of 10 Hz. Thus, the aim of the present research was to determine the reliability and accuracy of GPS devices operating at a sampling frequency of 10 Hz, in relation here to sprints of 15 m and 30 m and using both video and photoelectric cells.Nine trained male athletes participated in the study. Each participant completed 7 and 6 linear runs of 15 m and 30 m, respectively (n = 117, with only one GPS device being used per participant. Each repetition required them to complete the route as quickly as possible, with 1 min recovery between sets. Distance was monitored through the use of GPS devices (MinimaxX v4.0, Catapult Innovations, Melbourne, Australia operating at the above mentioned sampling frequency of 10 Hz. In addition, all tests were filmed with a video camera operating at a sampling frequency of 25 frames. Data were collected during what were considered to be good GPS conditions in terms of the weather and satellite conditions (number of satellites = 10.0 ± 0.2 and 10.3 ± 0.4 for sprints of 15 m and 30 m, respectively.Distance was measured using a tape measure. Electronic timing gates (TAG- Heuer, CP 520 Training model, Switzerland were used to obtain a criterion sprint time accurate to 0.01 s, with gates being placed at the beginning and end of the route (Petersen et

  9. Voice and GPS Based Navigation System for Visually Impaired

    Harsha Gawari

    2014-05-01

    Full Text Available The paper represents the architecture and implementation of a system that will help in the navigation of the visually impaired people. The system that we have designed uses GPS and voice recognition along with obstacle avoidance for the purpose of guiding visually impaired. The visually impaired person issues the command and receives the direction response using audio signals. The latitude and longitude values are received continuously from the GPS receiver. The directions are given to the user with the help of audio signals. An obstacle detector is used to help the user to avoid obstacles by sending an audio message.GPS receivers uses NMEA standard. With the advancement in voice recognition it becomes easier to issue commands regarding directions to the visually impaired.

  10. Investigation of GPS/IMU Positioning System for Mining Equipment

    Ken L. Stratton

    2006-09-13

    The objective of this project is to investigate the applicability of a combined Global Positioning System and Inertial Measurement Unit (GPS/IMU) for information based displays on earthmoving machines and for automated earthmoving machines in the future. This technology has the potential of allowing an information-based product like Caterpillar's Computer Aided Earthmoving System (CAES) to operate in areas with satellite shading. Satellite shading is an issue in open pit mining because machines are routinely required to operate close to high walls, which reduces significantly the amount of the visible sky to the GPS antenna mounted on the machine. An inertial measurement unit is a product, which provides data for the calculation of position based on sensing accelerations and rotation rates of the machine's rigid body. When this information is coupled with GPS it results in a positioning system that can maintain positioning capability during time periods of shading.

  11. The Aalborg Survey / Part 2 - GPS Based Survey

    Harder, Henrik; Christensen, Cecilie Breinholm; Henriksen, Susanne; Christensen, Rasmus Hamann; Poulsen, Jette Sommer; Simonsen, Anders Kvist; Tradisauskas, Nerius; Bro, Peter; Suenson, Valinka

    Background and purpose The Aalborg Survey consists of four independent parts: a web, GPS and an interview based survey and a literature study, which together form a consistent investigation and research into use of urban space, and specifically into young people’s use of urban space: what young...... research focus within the cluster of Mobility and Tracking Technologies (MoTT), AAU. Summary / Part 2 - GPS Based Survey The 2nd part of the DUS research project has been carried out during the months May-September 2008 and May 2009 as a quantitative GPS based activity survey of approximately 400, later...... reduced to 169, young people from the same sample population as in Part 1 – Web Based Survey, i.e. 7.680 young people studying at upper secondary schools in Aalborg [statistikbanken.dk, b]. The respondents have been chosen among those who participated in the Web Based Survey of Part 1. Furthermore, the...

  12. Bathymetric surveying with GPS and heave, pitch, and roll compensation

    Work, P.A.; Hansen, M.; Rogers, W.E.

    1998-01-01

    Field and laboratory tests of a shipborne hydrographic survey system were conducted. The system consists of two 12-channel GPS receivers (one on-board, one fixed on shore), a digital acoustic fathometer, and a digital heave-pitch-roll (HPR) recorder. Laboratory tests of the HPR recorder and fathometer are documented. Results of field tests of the isolated GPS system and then of the entire suite of instruments are presented. A method for data reduction is developed to account for vertical errors introduced by roll and pitch of the survey vessel, which can be substantial (decimeters). The GPS vertical position data are found to be reliable to 2-3 cm and the fathometer to 5 cm in the laboratory. The field test of the complete system in shallow water (surveying and equipment setup can minimize systematic error and yield much smaller average errors.

  13. GPS navigation on historical and modern geological maps

    Galambos, C.; Timár, G.; Székely, B.

    2009-04-01

    The usage of the georeferenced map in GIS applications provides the possibility to apply the geological maps in real-time GPS-navigation. In these tasks, both historical and modern geological maps can be applied. A georeferenced raster file of the geological map can be rendered as a background image in a GPS software on a Personal Digital Assistant (PDA). The software shows the actual position provided by the GPS on this background. Thus, the information of the geological map can be interpreted directly on the field at our position. Using this procedure using modern maps, it provides interesting new application for the users. The usage of historical maps is a possible application for the mapping geologists, too. In the present work, we give an algorithm of such an application and tackle the problem of the characteristic errors of this application.

  14. Use of a spatial GPS receiver in AMS-02 experiment

    An important subject in AMS02 experiment would be to perform measurements of the arrival time of the photons on a scale of few μsec for the Transient Gamma Sources, mainly Pulsars, Blazars and Gamma Ray Bursts. This may be possible if each trigger correlated with a detected cosmic particle, acquires a precise time stamp provided by a spatial GPS receiver which will also be used to synchronize the internal clocks of the AMS-02 DAQ system. The TOPSTAR 3000 D GPS receiver characteristics are described. The built in procedures for the integration of the GPS module in the DAQ and Trigger systems are presented. The dependence on the flight orbit, ISS in case of AMS-02 mission is studied. In final, the monitoring requirements and the first results of tests are discussed

  15. Voice and GPS Based Navigation System For Visually Impaired

    Harsha Gawari

    2014-04-01

    Full Text Available The paper represents the architecture and implementation of a system that will help to navigate the visually impaired people. The system designed uses GPS and voice recognition along with obstacle avoidance for the purpose of guiding visually impaired. The visually impaired person issues the command and receives the direction response using audio signals. The latitude and longitude values are received continuously from the GPS receiver. The directions are given to the user with the help of audio signals. An obstacle detector is used to help the user to avoid obstacles by sending an audio message.GPS receivers use NMEA standard. With the advancement in voice recognition it becomes easier to issue commands regarding directions to the visually impaired.

  16. Stability of VLBI, SLR, DORIS, and GPS positioning

    Feissel-Vernier, M.; de Viron, O.; Le Bail, K.

    2007-12-01

    The residual signal in VLBI, SLR, DORIS and GPS station motion, after a linear trend and seasonal components have been removed, is analysed to investigate site-specific and technique-specific error spectra. The study concentrates on 60 sites with dense observation history by two or more space geodetic techniques. The solutions analysed are single-analysis center solutions currently available. The GPS data are taken from the IGS files. Statistical methods include the Allan variance analysis and the three-cornered hat algorithm. The site-specific noise level is found to be in the range 0.5-3.5 mm in either horizontal direction and 1-4.5 mm in height for most sites. The distribution of site-specific noise type includes both white noise and flicker noise. White noise is predominant in the East direction. Both types of noise are found in the North direction, with no particular geographical clustering.Technique-specific noise characteristics are estimated in several ways, leading to a white noise diagnostic for VLBI and SLR in all three local directions. DORIS has also white noise in the horizontal directions, whereas GPS has a flicker noise spectrum. The vertical noise spectrum is indecisive for both DORIS and GPS. The three-dimensional noise levels for the one-year sampling time are 1.7 mm for VLBI, 2.5 mm for SLR, 5.2 mm for DORIS, and 4.1 mm for GPS. For GPS, the long-term analysis homogeneity has a strong influence. In the case of a test solution reanalysed in a fully consistent way, the noise level drops to the VLBI level in horizontal and to the SLR level in vertical. The three-dimensional noise level for a one-year sampling time decreases to 1.8 mm. In addition, the percentage of stations with flicker noise drops to only about 20% of the network.

  17. Precise levelling of the Olkiluoto GPS Network in 2005

    The GPS observation network of Olkiluoto was constructed in 1994 for monitoring crustal deformations at the investigation area. To fulfil a better vertical control of the GPS network, precise levellings were started at the area in autumn 2003. The levelling network consisted of the reserve mark pairs of eight GPS pillars and five levelling bench marks two of which constituted the nodal bench mark pair. The second precise levelling campaign on the area was carried out in autumn 2005. The same points as in autumn 2003 were levelled except one destroyed bench mark. In addition, one bench mark, one reserve mark pair and nine antenna platforms on the top of the GPS pillars were levelled. In total 32 points were levelled in 2005, of which eight reserve mark pairs, two bench marks and the nodal bench mark pair were common for both campaigns. Compared to the other points, the elevation difference of two reserve mark pairs had changed significantly during two years, about one millimetre. The reason may be the blasting of the rock in the neighbourhood of these points and deformation of the rock after the blasting. New precise levelling campaigns can shed more light on these movements. The next one will be carried out in autumn 2007. To monitor the possible vertical movement of whole Olkiluoto island, the GPS network was connected to the Finnish precise levelling net at Lapijoki in 2003. In the future this connection will be levelled every fourth year and the levelling of the GPS network will be carried out every second year. (orig.)

  18. Velocity Field Derived from Taiwan Continuous GPS Array (2007 - 2013

    Min-Chien Tsai

    2015-01-01

    Full Text Available Data were collected from 281 Taiwan continuous Global Positioning System (cGPS Array sites from 2007 - 2013 and processed with GAMIT/GLOBK software. Power spectral density stacking from cGPS position time series in Taiwan found the spectral index as -0.72, -0.77, and -0.57 for the E, N, U components, respectively. This indicates the cGPS data errors can be described as a combination of white noise and flicker noise. The common-mode errors are removed by stacking data from 50 cGPS sites with data periods greater than 5 years. By removing the common-mode errors the GPS data precision is further improved to 2.3, 1.9, and 6.9 mm in the E, N, U components, respectively. After strict data quality control, time series analysis and noise analysis, we derive a new Taiwan velocity field using cGPS data from 2007 - 2013. The general pattern of the newly derived 2007 - 2013 velocity field is quite similar to that from previous studies, but the station density is much larger and spatial coverage better. About 80 mm yr-1 plate convergence rate is observed, half of the rate is accommodated on the fold and thrust belt of western Taiwan and another half is taken up in the Longitudinal Valley and Coastal Range in eastern Taiwan. The velocities in western Taiwan generally show a fan-shaped pattern, consistent with the maximum compression tectonic stress direction. In northern Taiwan the velocity vectors reveal clockwise rotation, indicating the on-going extensional deformation related to the back-arc extension of the Okinawa Trough. In southern Taiwan, the horizontal velocity increases from about 40 mm yr-1 in the Chia-Nan area to 55 mm yr-1 in the Kao-Ping area with a counterclockwise rotation.

  19. A GPS-Based Pitot-Static Calibration Method Using Global Output-Error Optimization

    Foster, John V.; Cunningham, Kevin

    2010-01-01

    Pressure-based airspeed and altitude measurements for aircraft typically require calibration of the installed system to account for pressure sensing errors such as those due to local flow field effects. In some cases, calibration is used to meet requirements such as those specified in Federal Aviation Regulation Part 25. Several methods are used for in-flight pitot-static calibration including tower fly-by, pacer aircraft, and trailing cone methods. In the 1990 s, the introduction of satellite-based positioning systems to the civilian market enabled new inflight calibration methods based on accurate ground speed measurements provided by Global Positioning Systems (GPS). Use of GPS for airspeed calibration has many advantages such as accuracy, ease of portability (e.g. hand-held) and the flexibility of operating in airspace without the limitations of test range boundaries or ground telemetry support. The current research was motivated by the need for a rapid and statistically accurate method for in-flight calibration of pitot-static systems for remotely piloted, dynamically-scaled research aircraft. Current calibration methods were deemed not practical for this application because of confined test range size and limited flight time available for each sortie. A method was developed that uses high data rate measurements of static and total pressure, and GPSbased ground speed measurements to compute the pressure errors over a range of airspeed. The novel application of this approach is the use of system identification methods that rapidly compute optimal pressure error models with defined confidence intervals in nearreal time. This method has been demonstrated in flight tests and has shown 2- bounds of approximately 0.2 kts with an order of magnitude reduction in test time over other methods. As part of this experiment, a unique database of wind measurements was acquired concurrently with the flight experiments, for the purpose of experimental validation of the

  20. Vehicle teleoperation using 3D maps and GPS time synchronization.

    Suzuki, Taro; Amano, Yoshiharu; Hashizume, Takumi; Kubo, Nobuaki

    2013-01-01

    In conventional vehicle teleoperation systems, using low-bandwidth, high-delay transmission links causes a serious problem for remote control of the vehicles. To solve this problem, a proposed teleoperation system employs 3D maps and GPS time synchronization. Two GPS receivers measure the transmission delay, which the system uses to estimate the vehicle's location and orientation. Field experiments show that the 3D-map-based interface lets users easily comprehend the remote environment while navigating a vehicle. The experiments also show that taking communication delays into account improves maneuverability. PMID:24808084

  1. Satellite emission radio interferometric earth surveying series - GPS geodetic system

    Macdoran, P. F.

    1979-01-01

    A concept called SERIES (satellite emissions radio interferometric earth surveying) which makes use of GPS (global positioning system) radio transmissions without any satellite modifications, is described. Through the use of very long baseline interferometry (VLBI) and its calibration methods, 0.5 to 3 cm three dimensional baseline accuracy can be achieved over distances of 2 to 200 km respectively, with only 2 hours of on-site data acquisition. Attention is given to such areas as: the radio flux equivalent of GPS transmissions, synthesized delay precision, transmission and frequency subsystem requirements, tropospheric and ionospheric errors. Applications covered include geodesy and seismic tectonics.

  2. Autonomous GPS/INS navigation experiment for Space Transfer Vehicle

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

    1993-01-01

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

  3. Trimble IS Il rilievo integrato tra Total Station e GPS

    Redazione Redazione

    2005-10-01

    Full Text Available Le tecniche di Rilievo Integrato sono state introdotte per la prima volta da Trimble nel 1998 con il controller GeodatWin. GeodatWin è stato il primo controller a permettere la connessione ed il controllo sia per i ricevitori GPS che per gli strumenti topografici convenzionali. I dati registrati da ciascun dispositivo venivano memorizzati e gestiti in un unico file di lavoro, consentendo così la misura dei punti indifferentementesia con apparati GPS che con strumenti convenzionali.

  4. Crustal deformation parameters using GPS measurements on the Romanian territory

    The main objective of EU Project CERGOP (Central European Regional Geodynamic Project) is represented by the activity of integration of all geodynamic studies in the Central European area, based on spatial geodetic measurements of high precision (GPS) which were carried out on the territory of 11 European countries. In this frame there were performed GPS measurements in eight points geodetic network inside Romanian territory covering the main tectonic features of the area. In our study there were computed the main deformation parameters (accumulated strain) using finite element method for the interval of time between two sessions of measurements (1995-1996). (authors)

  5. A Parkes half-Jansky sample of GPS galaxies

    Snellen, I.A.G.; Lehnert, M. D.; Bremer, M. N.; Schilizzi, R. T.

    2002-01-01

    This paper describes the selection of a new southern/equatorial sample of Gigahertz Peaked Spectrum (GPS) radio galaxies, and subsequent optical CCD imaging and spectroscopic observations using the ESO 3.6m telescope. The sample consists of 49 sources with -400.5 Jy, selected from the Parkes PKSCAT90 survey. About 80% of the sources are optically identified, and about half of the identifications have available redshifts. The R-band Hubble diagram and evolution of the host galaxies of GPS sour...

  6. GPR and GPS data integration: examples of application in Antarctica

    S. Gandolfi

    2001-06-01

    Full Text Available Ground Penetrating Radar (GPR and Global Positioning System (GPS techniques were employed in snow accumulation studies during the Italian leg of the International Trans-Antarctic Scientific Expedition (ITASE. The acquired data were useful both for glaciological and climatological studies. This paper presents some results obtained by GPR and GPS data integration employed to determine accumulation/ablation processes along the profile of the traverse that show how the snow-sublayer thickness can vary quickly in just a few kilometres. Some examples of data integration employed in detection and characterisation of buried crevasses are also presented.

  7. Sensing and Classifying Impairments of GPS Reception on Mobile Devices

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

    2011-01-01

    degradation on modern smart phones for different hand grip styles and body placements can cause signal strength drops as high as 10-16 dB and double the positioning error. Furthermore, existing phone applications designed to help users identify sources of GPS performance impairment are restricted to show raw...... proposed autonomous method can identify and differentiate such sources, and thus also user environments and phone postures, with reasonable accuracy, while relying solely on GPS receiver data as it is available on most modern smart phones....

  8. Relationships between GPS-signal propagation errors and EISCAT observations

    Jakowski, N.; Sardon, E.; Engler, E.; Jungstand, A.; Klähn, D.

    1996-12-01

    When travelling through the ionosphere the signals of space-based radio navigation systems such as the Global Positioning System (GPS) are subject to modifications in amplitude, phase and polarization. In particular, phase changes due to refraction lead to propagation errors of up to 50 m for single-frequency GPS users. If both the L1 and the L2 frequencies transmitted by the GPS satellites are measured, first-order range error contributions of the ionosphere can be determined and removed by difference methods. The ionospheric contribution is proportional to the total electron content (TEC) along the ray path between satellite and receiver. Using about ten European GPS receiving stations of the International GPS Service for Geodynamics (IGS), the TEC over Europe is estimated within the geographic ranges -20°leqleq40°E and 32.5°leqleq70°N in longitude and latitude, respectively. The derived TEC maps over Europe contribute to the study of horizontal coupling and transport proces- ses during significant ionospheric events. Due to their comprehensive information about the high-latitude ionosphere, EISCAT observations may help to study the influence of ionospheric phenomena upon propagation errors in GPS navigation systems. Since there are still some accuracy limiting problems to be solved in TEC determination using GPS, data comparison of TEC with vertical electron density profiles derived from EISCAT observations is valuable to enhance the accuracy of propagation-error estimations. This is evident both for absolute TEC calibration as well as for the conversion of ray-path-related observations to vertical TEC. The combination of EISCAT data and GPS-derived TEC data enables a better understanding of large-scale ionospheric processes. Acknowledgements. This work has been supported by the UK Particle-Physics and Astronomy Research Council. The assistance of the director and staff of the EISCAT Scientific Association, the staff of the Norsk Polarinstitutt and the

  9. Virtual Security Zones for Student Tracking System Using GPS Watch

    Keerthi Priya.D; Gopalakrishnan S

    2014-01-01

    This Project is to design and develop a smart GPS watch that will track the position of the attached person (ex: school children & elderly), monitors for a sudden fall and alerts the authority in the event of a fall or when that person crosses a given border line of a predefined zone using a combination of GSM and WPAN radio communication. Since this is a security system, GPS watch should be always attached to the monitored person and removing or damaging this device should be pro...

  10. Use of Loran-C navigation system to accurately determine sampling site location in an above ground cooling reservoir

    Environmental monitoring programs often require accurate determination of sampling site locations in aquatic environments. This is especially true when a open-quotes pictureclose quotes of high resolution is needed for observing a changing variable in a given area and location is assumed to be important to the distribution of that variable. Sample site location can be difficult if few visible land marks are available for reference on a large body of water. The use of navigational systems such as Global Positioning System (GPS) and its predecessor, Loran-C, provide an excellent method for sample site location. McFarland (1992) discusses the practicality of GPS for location determination. This article discusses the use of Loran-C in a sampling scheme implemented at the South Texas Project Electrical Generating Station (STPEGS), Wadsworth, Texas

  11. Vähemalt kolm hunti saavad veel GPS-kaelused / Madis Filippov

    Filippov, Madis

    2011-01-01

    Esimene Eesti hunt sai kaela GPS-seadme, mis hakkab edastama teavet looma toitumise ja elupiirkonna kohta, lähiajal on plaanis samasuguse seadme paigaldamine veel vähemalt kolmele hundile. GPS loomadel

  12. Application and Limitations of GPS Radio Occultation (GPS-RO) Data for Atmospheric Boundary Layer Height Detection over the Arctic.

    Ganeshan, M.; Wu, D. L.

    2014-12-01

    Due to recent changes in the Arctic environment, it is important to monitor the atmospheric boundary layer (ABL) properties over the Arctic Ocean, especially to explore the variability in ABL clouds (such as sensitivity and feedback to sea ice loss). For example, radiosonde and satellite observations of the Arctic ABL height (and low-cloud cover) have recently suggested a positive response to sea ice loss during October that may not occur during the melt season (June-September). Owing to its high vertical and spatiotemporal resolution, an independent ABL height detection algorithm using GPS Radio Occultation (GPS-RO) refractivity in the Arctic is explored. Similar GPS-RO algorithms developed previously typically define the level of the most negative moisture gradient as the ABL height. This definition is favorable for subtropical oceans where a stratocumulus-topped ABL is often capped by a layer of sharp moisture lapse rate (coincident with the temperature inversion). The Arctic Ocean is also characterized by stratocumulus cloud cover, however, the specific humidity does not frequently decrease in the ABL capping inversion. The use of GPS-RO refractivity for ABL height retrieval therefore becomes more complex. During winter months (December-February), when the total precipitable water in the troposphere is a minimum, a fairly straightforward algorithm for ABL height retrieval is developed. The applicability and limitations of this method for other seasons (Spring, Summer, Fall) is determined. The seasonal, interannual and spatial variability in the GPS-derived ABL height over the Arctic Ocean, as well as its relation to the underlying surface (ice vs. water), is investigated. The GPS-RO profiles are also explored for the evidence of low-level moisture transport in the cold Arctic environment.

  13. Synthesis Analysis of One Severe Convection Precipitation Event in Jiangsu Using Ground-Based GPS Technology

    Hao Wang; Jianxin He; Ming Wei; Zhendong Zhang

    2015-01-01

    Global positioning system (GPS) detection technology has several advantageous characteristics (i.e., all-weather applications, high accuracy, high spatial and temporal resolution, and low cost), and GPS tracking and monitoring techniques for water vapor have developed rapidly in recent years. The GPS-precipitable water vapor (GPS-PWV), obtained through inversion using this technology can reflect the water vapor inflow and outflow in a vertical air column above a certain area in nearly real-ti...

  14. Positioning with Inertial Sensors and Aid Sensors when loosing GPS Fix

    Mathiassen, Kim

    2010-01-01

    This thesis designs a multipurpose navigation unit. The unit is equipped with a GPS which is the primary navigation sensor, when the GPS satellites are available. If the GPS satellites becomes unavailable, a inertial system with aid sensors is used for navigation. A unit that collects data from a GPS, gyroscopes, accelerometers, magnetometers and a barometer has been developed in a project leading to this thesis. The software development was not completed. The software responsible for commun...

  15. Prevalence and predictors of occupational violence and aggression towards GPs: a cross-sectional study

    Koritsas, Stella; Coles, Jan; Boyle, Malcolm; Stanley, Janet

    2007-01-01

    Occupational violence and aggression are common in general practice. This study examined occupational violence and aggression against GPs in terms of prevalence and predictive factors, such as sex of GP and practice location. Over half of the GPs sampled had experienced at least one form of violence and aggression; more female than male GPs experienced sexual harassment; and there was no difference in the number of metropolitan and rural GPs who had experienced violence and aggression. Predic...

  16. Monitoring beach changes using GPS surveying techniques

    Morton, Robert; Leach, Mark P.; Paine, Jeffrey G.; Cardoza, Michael A.

    1993-01-01

    A need exists for frequent and prompt updating of shoreline positions, rates of shoreline movement, and volumetric nearshore changes. To effectively monitor and predict these beach changes, accurate measurements of beach morphology incorporating both shore-parallel and shore-normal transects are required. Although it is possible to monitor beach dynamics using land-based surveying methods, it is generally not practical to collect data of sufficient density and resolution to satisfy a three-dimensional beach-change model of long segments of the coast. The challenge to coastal scientists is to devise new beach monitoring methods that address these needs and are rapid, reliable, relatively inexpensive, and maintain or improve measurement accuracy.

  17. A novel behavioral model of the pasture-based dairy cow from GPS data using data mining and machine learning techniques.

    Williams, M L; Mac Parthaláin, N; Brewer, P; James, W P J; Rose, M T

    2016-03-01

    A better understanding of the behavior of individual grazing dairy cattle will assist in improving productivity and welfare. Global positioning systems (GPS) applied to cows could provide a means of monitoring grazing herds while overcoming the substantial efforts required for manual observation. Any model of behavioral prediction using GPS needs to be accurate and robust by accounting for inter-cow variation as well as atmospheric effects. We evaluated the performance using a series of machine learning algorithms on GPS data collected from 40 pasture-based dairy cows over 4mo. A feature extraction step was performed on the collected raw GPS data, which resulted in 43 different attributes. The evaluated behaviors were grazing, resting, and walking. Classifier learners were built using 10 times 10-fold cross validation and tested on an independent test set. Results were evaluated using a variety of statistical significance tests across all parameters. We found that final model selection depended upon level of performance and model complexity. The classifier learner deemed most suitable for this particular problem was JRip, a rule-based learner (classification accuracy=0.85; false positive rate=0.10; F-measure=0.76; area under the receiver operating curve=0.87). This model will be used in further studies to assess the behavior and welfare of pasture-based dairy cows. PMID:26805984

  18. General practitioners (GPs) and palliative care: perceived tasks and barriers in daily practice.

    Groot, C.M.; Vernooy-Dassen, M.J.F.J.; Crul, B.J.P.; Grol, R.P.T.M.

    2005-01-01

    BACKGROUND: General practitioners (GPs) play a crucial part in palliative care. The quality of care can be improved by investigating and addressing barriers perceived by GPs in daily practice. The aim of this study was to investigate GPs' task perception and barriers involved in palliative care. MET

  19. Road Charging in Copenhagen: A Comparative Study of the GPS Performance

    Zabic, Martina

    2009-01-01

    The paper presents results from a comparative study on the GPS performance based on experiments carried out in Copenhagen, Denmark in both 2003 and 2008. GPS data from 40 vehicles were collected to re-evaluate the GPS performance in a Danish environment and thereby assess the level of performance...

  20. Pandora's electronic box: GPs reflect upon email communication with their patients

    Felicity Goodyear-Smith

    2005-11-01

    Conclusion Study sample closely mirrored current NZ GP population. Although few GPs emailed with patients, many might once barriers are addressed. GPs had a collective view of the appropriate boundaries for email communication, routine tasks and the transmission of information. GPs would encourage professional debate regarding guidelines for good practice, managing demand and remuneration.

  1. 77 FR 56254 - 89th Meeting: RTCA Special Committee 159, Global Positioning Systems (GPS)

    2012-09-12

    ... Federal Aviation Administration 89th Meeting: RTCA Special Committee 159, Global Positioning Systems (GPS... Notice of RTCA Special Committee 159, RTCA Special Committee 159, Global Positioning Systems (GPS... Special Committee 159, Global Positioning Systems (GPS). DATES: The meeting will be held October 5,...

  2. 76 FR 27744 - Eighty-Fifth Meeting: RTCA Special Committee 159: Global Positioning System (GPS)

    2011-05-12

    ... System (GPS) AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 159 meeting: Global Positioning System (GPS). SUMMARY: The FAA is issuing this notice to advise the public of a meeting of RTCA Special Committee 159: Global Positioning System (GPS). DATES: The...

  3. 78 FR 13396 - 90th Meeting: RTCA Special Committee 159, Global Positioning Systems (GPS)

    2013-02-27

    ... Federal Aviation Administration 90th Meeting: RTCA Special Committee 159, Global Positioning Systems (GPS... Notice of RTCA Special Committee 159, RTCA Special Committee 159, Global Positioning Systems (GPS... Special Committee 159, Global Positioning Systems (GPS). DATES: The meeting will be held March 12-15,...

  4. 78 FR 57672 - 91st Meeting: RTCA Special Committee 159, Global Positioning Systems (GPS)

    2013-09-19

    ... Federal Aviation Administration 91st Meeting: RTCA Special Committee 159, Global Positioning Systems (GPS... Notice of RTCA Special Committee 159, RTCA Special Committee 159, Global Positioning Systems (GPS... Special Committee 159, Global Positioning Systems (GPS) DATES: The meeting will be held October 7-11,...

  5. 75 FR 28318 - Eighty-Second Meeting: RTCA Special Committee 159: Global Positioning System (GPS)

    2010-05-20

    ... System (GPS) AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 159 meeting: Global Positioning System (GPS). SUMMARY: The FAA is issuing this notice to advise the public of a meeting of RTCA Special Committee 159: Global Positioning System (GPS). DATES: The...

  6. Remote landslide mapping using a laser rangefinder binocular and GPS

    M. Santangelo

    2010-12-01

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

  7. Real null coframes in general relativity and GPS type coordinates

    Blagojevic, M; Hehl, F W; Obukhov, Yu N; Obukhov, Yu.N.

    2002-01-01

    Some time ago, D. Finkelstein defined a `symmetric' null frame with {\\it four real null vectors}. We discuss this Finkelstein frame and show that a similarly defined real null coframe is closely related to the GPS type coordinates recently introduced by Rovelli.

  8. Coloured noise effects on deformation parameters of permanent GPS networks

    Razeghi, S. M.; Amiri-Simkooei, A. R.; Sharifi, M. A.

    2016-03-01

    Deformation analysis in general and strain analysis in particular using permanent GPS networks require proper analysis of time-series in which all functional effects are taken into consideration and all stochastic effects are captured using an appropriate noise model. This contribution addresses both issues when considering the strain parameters of a GPS network. Estimates of spatial correlation, time correlated noise, and multivariate power spectrum for daily position time-series of the Southern California Integrated GPS Network (SCIGN) stations collected between 1996 and 2011 are obtained. Significant signals with periods of 13.63 d and those related to the GPS draconitic year are identified in these time-series. We aim to assess the effect of a realistic noise model of the series on the uncertainties of the strain parameters including displacements, normal and shear strains, and rotations. For the SCIGN network considered, the following results are highlighted. Contrary to the common belief, the uncertainties of the displacements parameters become smaller when taking a realistic noise model into account. This however was not the case when assessing the noise characteristics of the normal and shear strain, and rotation parameters. The uncertainties increase nearly by a factor of two, in agreement to what is expected. Some of the significant deformation parameters of the white noise model become less significant in case of the realistic noise model.

  9. Precise Real-Time Low Earth Orbitor Navigation With GPS

    Bertiger, W.; Haines, B.; Kuang, D.; Lough, M.; Lichten, S.; Muellerschoen, R. J.; Vigue, Y.; Wu, S.

    1998-01-01

    Technology is currently available to support real-time on-board knowledge of the position of a low earth orbitor at the 5-15 meter level using the civilian broadcast GPS signal with sophisticated models and filtering techniques onboard the spacecraft.

  10. GPs motivations of prescribing antidepressants and their practical relevance.

    Volkers, A.; Jong, A. de; Braspenning, J.C.C.; Bakker, D. de; Dijk, L. van

    2004-01-01

    Background: Insight in the motivations of prescribing antidepressants may contribute to advance the efficiency of the current, large antidepressant prescription rate. Less is known about why general practitioners (GPs) treat patients with antidepressants or not and choose modern SSRIs instead of the

  11. GPS/MEMS IMU/Microprocessor Board for Navigation

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

    2009-01-01

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

  12. Dual-band circularly polarized microstrip antenna for GPS application

    Fujimoto, Takafumi; Ayukawa, Daisuke; Iwanaga, Kouhei; Taguchi, Mitsuo

    2008-01-01

    In this paper, the small dual-band circularly polarized square MSAs for GPS application is proposed and the operational principles and the characteristics of the antenna are clarified by the simulator. The antenna consists of a square patch with slits and four T-shaped elements. The T-shaped element is loaded at each slit of the square patch.

  13. Using GPS-tracking technology for urban design interventions

    Van der Spek, S.C.; Van Langelaar, C.M.

    2011-01-01

    The aim of this paper is to express the application of tracking technologies in Urban Design and Planning. Tracking technologies can be used to monitor different user groups in different occasions. Since 2005, TU Delft has explored and developed two types of research using GPS to collect spatio temp

  14. Evaluation of Mobile Phone Interference With Aircraft GPS Navigation Systems

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

    2004-01-01

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

  15. Development and Validation of the Game Perception Scale (GPS)

    Vandercruysse, Sylke; Vandewaetere, Mieke; Maertens, Marie; ter Vrugte, Judith; Wouters, Pieter; de Jong, Ton; van Oostendorp, Herre; Elen, Jan

    2015-01-01

    Despite the pervasiveness of perception and considerable impact of perception on the use of ICT for educational purposes, there is a surprising paucity of perception assessment instruments. The present proposal expands on this through the development and initial validation of the Game Perception Scale (GPS). Based on perception literature,…

  16. Evaluation of timing GPS receivers for industrial applications

    Vigner, V.; Roztočil, J.; Čemusová, Blanka

    Florencie: Universita di Firenze, 2013 - (Sente, P.), s. 177-182 ISBN 9788890314988. [12th IMEKO TC10 Workshop on Technical Diagnostics: New Perspective in Measurements, Tools and Techniques for Industrial Applications. Florence (IT), 06.06.2013-07.06.2013] Institutional support: RVO:67985882 Keywords : GPS receivers * Reference time * Stability evaluation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  17. Grazing Behavior of Heifers Measured by Handheld GPS

    The objective of this study was to assess how previous grazing experience affects animal movement on pasture. Portable GPS units were used to monitor movements of 32 Holstein (n=21) and Holstein-Jersey (n=11) yearlings. Total distance walked was measured and analyzed as a randomized complete block e...

  18. GPS: Shaping Student Success One Conversation at a Time

    Star, Mikhael; Collette, Lanita

    2010-01-01

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

  19. Jason-1 and Jason-2 POD Using GPS

    Melachroinos, Stavros; Lemoine, Frank G.; Zelensky, Nikita P.; Rowlands, David D.; Luthcke, Scott B.; Beckley, Brian D.

    2012-01-01

    The Jason-2 satellite, launched in June 2008, is the latest follow-on to the successful Jason-1 altimetry satellite mission launched in December 7, 2001. Both, Jason-2 and Jason-1 are equipped with a GPS dual-frequency receiver, a laser retroreflector array, and a DORIS receiver for precise orbit determination (POD). A series of dynamic and reduced-dynamic Jason-2 orbits computed at NASA GSFC, based on GPS-only data and the std0905 standards, have been completed till cy74through cycle 74 using the IGS05 framework. These orbits, now publicly available, have been shown to agree radially at 1 cm RMS with the GSFC std0905 SLR/DORIS orbits and in comparison with orbits produced by JPL, ESA and CNES. In this paper, we describe the implementation of the IGS08 and repro1 framework for the Jason-2 and Jason-1 GPS POD processing with the NASA GSFC GEODYN software. . In our updated GPS POD, ambiguity fixing and updated time variable and static gravity fields. We also evaluate the implementation of non-tidal and degree-1 loading displacement as forward modeling to the tracking stations. Reduced-dynamic versus dynamic orbit differences are used to characterize the remaining force model errors and TRF instability. In particular, we assess their consistency radially and the stability of the altimeter satellite reference frame in the North/South direction as a proxy to assess the consistency of the reference frame.

  20. Detecting Traffic Anomalies in Urban Areas Using Taxi GPS Data

    Weiming Kuang

    2015-01-01

    Full Text Available Large-scale GPS data contain hidden information and provide us with the opportunity to discover knowledge that may be useful for transportation systems using advanced data mining techniques. In major metropolitan cities, many taxicabs are equipped with GPS devices. Because taxies operate continuously for nearly 24 hours per day, they can be used as reliable sensors for the perceived traffic state. In this paper, the entire city was divided into subregions by roads, and taxi GPS data were transformed into traffic flow data to build a traffic flow matrix. In addition, a highly efficient anomaly detection method was proposed based on wavelet transform and PCA (principal component analysis for detecting anomalous traffic events in urban regions. The traffic anomaly is considered to occur in a subregion when the values of the corresponding indicators deviate significantly from the expected values. This method was evaluated using a GPS dataset that was generated by more than 15,000 taxies over a period of half a year in Harbin, China. The results show that this detection method is effective and efficient.