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  • A network approach for strapdown inertial kinematic gravimetry.

     Termens Perarnau, M. Assumpció
    Defense's date: 2014-03-07
    Universitat Politècnica de Catalunya
    Theses

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    En comparació amb la gravimetria terrestre, la gravimetria aerotransportada és més eficient i rendible. Especialment, la combinació de INS i GPS és ben coneguda per mostrar molts bons resultats al recuperar el senyal de la gravetat en el rang de freqüències mitjanes (1--100 km).L'extracció de les anomàlies de gravetat a partir de gravimetria aerotransportada SINS s'ha basat principalment en l'aproximació SSA, que té molts avantatges, però que mostra un greu inconvenient, a saber, la capacitat molt limitada per tractar les correlacions espacials (com el tractament rigorós dels punts d'encreuament o cross-overs).Aquesta tesi examina una alternativa a través de la coneguda aproximació en xarxes extensament usada en geodèsia, en el que les equacions diferencials de mecanització del INS s'interpreten com equacions d'observació d'un problema d'estimació de paràmetres per mínims-quadrats.En termes numèrics, les equacions de mecanització INS es resolen per un mètode de diferències finites, on els valors inicials de frontera se substitueixen per equacions d'observació. L'autora considera que l'enfocament exposat té algunes avantatges que val la pena explorar; sobretot, la modelització del camp gravitatori terrestre pot ser més rigorós que amb SSA i les equacions d'observació poden ser explotades millor.És important assenyalar que aquest enfocament no es pot aplicar a la navegació en temps real. Tanmateix, en aquest cas no es tracta de resoldre un problema de navegació, sino un de geodèsic.En aquesta dissertació es presentaran diferents maneres de tractar aquest sistema d'equacions lineals i es mostraran alguns resultats pràctics a partir de dades simulades.

  • Two-component model of topside ionosphere electron density profiles retrieved from GNSS radio occultations

     Gonzalez Casado, Guillermo; Juan Zornoza, Jose Miguel; Hernandez Pajares, Manuel; Sanz Subirana, Jaime
    Journal of geophysical research
    Date of publication: 2013
    Journal article

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    A simple model for the topside ionosphere region is introduced and applied to fit radio-occultation retrieved electron density profiles for altitudes above the F2-peak. The model considers two isothermal components representing the population of the O+ (ionosphere component) and the H+ (protonosphere component) ions. The purpose of the model is to achieve an accurate fit of the observed profiles in the topside ionosphere region while, at the same time, allowing a direct and simple derivation of two important ionospheric parameters, namely, the O+ vertical scale height and the upper transition height. Covering a time period of one year, the fits with the two-component model function are compared with those achieved with one-component functions commonly used in the literature and it is shown that the former provides significantly better fits than the later, with more than a factor of two improvement. The model predictions concerning: the correlation between the O+ vertical scale height and the upper transition height, the altitude dependence of the vertical scale height of the electron density, and the quantitative contribution of the protonosphere to the total electron content are examined and shown to be consistent with the observations and with previous studies. It is concluded that the model provides a realistic description of the vertical distribution of the two main ion constituents of the topside ionosphere.

  • Definition of an SBAS ionospheric activity indicator and its assessment over Europe and Africa During the last solar cycle

     Sanz Subirana, Jaime; Juan Zornoza, Jose Miguel; Hernandez Pajares, Manuel; Prieto Cerdeira, Roberto; Schlueter, Stefan
    International Beacon Satellite Symposium
    Presentation's date: 2013-07
    Presentation of work at congresses

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    In this work, an ionospheric activity indicator is defined based in the ¿weighted¿ Along Arc TEC rate (AATR). It is shown that this indicator, which can be easily computed from the GPS carrier phases, is well correlated with the ionospheric activity and, unlike other global indicators linked to the geomagnetic activity, can be sensitive to regional behaviours of ionospheric activity

  • Solar EUV flux rate estimation during mid and strong flares from the ionospheric electron content response signature in GNSS observations

     Hernandez Pajares, Manuel; Garcia Rigo, Alberto; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime; Monte Moreno, Enrique; Aragon Angel, Maria Angeles
    European Conference on Antennas and Propagation
    Presentation's date: 2013-04-08
    Presentation of work at congresses

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    A simple and precise technique to measure the sudden Extreme Ultraviolet (EUV) radiation increase of the Sun, during mid and strong flares, has been formulated and demonstrated for the most active part of the last Solar Cycle. On the one hand, it is based on the short time scale of these events, which allows the validity of a simple global overionization model. And on the other hand on the prompt ionospheric response to the EUV ionization, which signature (in terms of the Global Navigation Satellite Systems -GNSSSolar Flare Activity Indicator, GSFLAI) is accurately measured in real-time from the existing global networks of dual-frequency GNSS receivers, and with a time resolution higher that those of dedicated space probes. Moreover the sensitivity of this approach enables the detection of not only extreme X-class flares, but also the detection of variations of one order of magnitude lower or even smaller (such as for M-class flares): 100% successful detection for all the X-class solar flares during 2000-2006 with registered location outside of the solar limb (i.e. detection of 94% of all of X-class solar-flares) and about 65% for M-class ones, obtained with the associated SISTED detector. In summary, its full availability, continuity, high precision and integrity for mid and high solar flare effects on Ionosphere, can make GSFLAI an useful indicator of potential Space Weather activity for many users in radio propagation. These results, which have been recently published by the authors, are extended in this work up to one complete solar cycle, and using a lower sampling rate (30 seconds), demonstrating the better behaviour of this indirect solar EUV variability proxy (GSFLAI30), when comparisons are made with direct measurements from space probes, providing readings which can be affected by the late enhancement of particles.

  • Characterization and modelling of the ionosphere for EGNOS development and qualification

     Schlüter, S.; Prieto Cerdeira, Roberto; Orús Pérez, Raul; Lam, J.P.; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime; Hernandez Pajares, Manuel
    The European Navigation Conference
    Presentation's date: 2013-04-23
    Presentation of work at congresses

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    The availability of representative data samples, models and statistical information derived from the analysis of parameters that adequately describe the state of the ionosphere are key elements for the design, verification and qualification of EGNOS algorithms. As part of the on-going evolutions of EGNOS V2 releases, and also in support to the development of a future multi-constellation and dual-frequency SBAS (EGNOS V3), ESA has started a refinement process of the tools, data and precise definition of the ionospheric operational conditions. A particular driver for this process is the improvement of the availability performance of the current and future system especially under solar max and severe ionospheric conditions, without degradation of integrity and accuracy performances. The paper provides an overview about the concept and the data and models used for EGNOS development and qualification. It outlines the approaches to generate reference models and describes the parameter used for the characterization of nominal and perturbed ionospheric conditions from an SBAS perspective.

  • New indicator for definition of ionospheric operational conditions

     Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime; Hernandez Pajares, Manuel; Prieto Cerdeira, Roberto; Schlueter, Stefan
    SBAS-IONO
    Presentation's date: 2013-07-12
    Presentation of work at congresses

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  • GIM-TEC adaptive ionospheric weather assessment and forecast system

     Gulyaeva, Tamara L.; Arikan, Feza; Hernandez Pajares, Manuel; Stanislawska, Iwona
    Journal of atmospheric and solar-terrestrial physics
    Date of publication: 2013-09
    Journal article

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  • GNSS Data Processing, Vol 2: Laboratory exercises , (ESA TM-23/2, May 2013)

     Sanz Subirana, Jaime; Juan Zornoza, Jose Miguel; Hernandez Pajares, Manuel
    Date of publication: 2013-05-01
    Book

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    This two-volume book contains a self-learning course and software tools aimed at providing the necessary background to start work in an operative way in GNSS navigation. The books are focused on the instrumental use of concepts and techniques involved in GNSS navigation and include all the elements needed to understand how the system works and how to work with it. After working through the two volumes, students should be able to develop their own tools for high-accuracy navigation, implementing the algorithms and expanding the skills learned. The first volume is devoted to theory, providing a summary of GNSS fundamentals and algorithms. The second volume is devoted to laboratory exercises, with a wide range of selected practical examples going further into the theoretical concepts and their practical implementation. The exercises have been developed with a specialised software package (the ESA/U PC gLAB educational SW, on an attached CD) and selected data files are provided for the laboratory sessions.

  • GNSS Data Processing, Vol1: Fundamentals and Algorithms, (ESA TM-23/1, May 2013)

     Sanz Subirana, Jaime; Juan Zornoza, Jose Miguel; Hernandez Pajares, Manuel
    Date of publication: 2013-05-01
    Book

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    This two-volume book contains a self-learning course and software tools aimed at providing the necessary background to start work in an operative way in GNSS navigation. The books are focused on the instrumental use of concepts and techniques involved in GNSS navigation and include all the elements needed to understand how the system works and how to work with it. After working through the two volumes, students should be able to develop their own tools for high-accuracy navigation, implementing the algorithms and expanding the skills learned. The first volume is devoted to theory, providing a summary of GNSS fundamentals and algorithms. The second volume is devoted to laboratory exercises, with a wide range of selected practical examples going further into the theoretical concepts and their practical implementation. The exercises have been developed with a specialised software package (the ESA/U PC gLAB educational SW, on an attached CD) and selected data files are provided for the laboratory sessions. This is an end-to-end GNSS course addressed to all professionals and students who wish to undertake a deeper study of satellite navigation, targeting the GNSS data processing and analysis issues.

  • E-04001

     Garcia Rigo, Alberto; Hernandez Pajares, Manuel
    Participation in a competitive project

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  • Impact of higher order ionospheric delay on precise GNSS computation

     Hernandez Pajares, Manuel; Aragon Angel, Maria Angeles; Defraigne, Pascale; Bergeot, Nicolas; Prieto Cerdeira, Roberto; Sanz Subirana, Jaime
    International Colloquium Scientific and Fundamental Aspects of the Galileo Programme
    Presentation's date: 2013-12
    Presentation of work at congresses

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  • Enhanced precise point positioning for GNSS users

     Juan Zornoza, Jose Miguel; Hernandez Pajares, Manuel; Sanz Subirana, Jaime; Ramos Bosch, Pedro; Aragon Angel, Maria Angeles; Orús Pérez, Raul; Ochieng, Washington; Feng, Shaojun; Jofre, Martí; Coutinho, Pedro; Samson, Jaron; Tossaint, Michel Mathias Maria
    IEEE transactions on geoscience and remote sensing
    Date of publication: 2012-09-21
    Journal article

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    This paper summarizes the main results obtained during the development of an Enhanced Precise Point Positioning (EPPP) Global Navigation Satellite Systems multifrequency user algorithm. The main innovations include the application of precise ionospheric corrections to facilitate the resolution of undifferenced carrier phase ambiguities, ambiguity validation, and integrity monitoring. The performance of the EPPP algorithm in terms of accuracy, convergence time, and integrity is demonstrated with actual GPS and simulated Galileo data. This can be achieved with very limited bandwidth requirements for EPPP users (less than 300 b/s for dual-frequency GPS data).

    This paper summarizes the main results obtained during the development of an Enhanced Precise Point Positioning (EPPP) Global Navigation Satellite Systems multifrequency user algorithm. The main innovations include the application of precise ionospheric corrections to facilitate the resolution of undifferenced carrier phase ambiguities, ambiguity validation, and integrity monitoring. The performance of the EPPP algorithm in terms of accuracy, convergence time, and integrity is demonstrated with actual GPS and simulated Galileo data. This can be achieved with very limited bandwidth requirements for EPPP users (less than 300 b/s for dual-frequency GPS data).

  • Fast Precise Point Positioning for decimeter-error-level navigation for multi and single-frequency users of Global Navigation Satellite Systems

     Juan Zornoza, Jose Miguel; Hernandez Pajares, Manuel; Sanz Subirana, Jaime; Samson, J.; Tossaint, M.
    European Calibration and Orientation Workshop
    Presentation's date: 2012-02
    Presentation of work at congresses

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    This manuscript summarizes the new algorithm of Fast Precise Point Positioning (FPPP) the developed during the projects "Enhanced PPP GNSS multifrequency user algorithm" and ¿Precise Real Time Orbit Determination and Time synchronisation¿, both funded by the European Space Agency (ESA). The main innovations achieved during the overall project comprise the application of precise ionospheric corrections to facilitate the fast resolution of undifferenced carrier phase ambiguities, ambiguity validation and integrity monitoring for both multi- and single-frequency users. Among the integrity, detailed in previous works, the performance of the FPPP algorithm in terms of improved accuracy and convergence time is demonstrated with actual GPS and simulated Galileo data. The 10-centimeters error level real-time kinematic positioning can be achieved in few minutes for dual-and single-frequency users, almost instantaneous for three-frequency users (or once the tropospheric delay is well estimated in few minutes in cold start), and with very limited bandwidth requirements for the FPPP users (less than 300 bps for dual-frequency GPS)

  • Fast precise point positioning performance based on international GNSS real-time service data

     Rovira Garcia, Adrià; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime; Hernandez Pajares, Manuel
    ESA Workshop on Satellite Navigation Technologies
    Presentation's date: 2012-12-05
    Presentation of work at congresses

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  • Ionospheric effects on GNSS performance

     Béniguel, Yannick; Angling, M; Banfi, E.; Bourga, C.; Cueto, M.; Fleury, R.; Garcia Rigo, Alberto; Hamel, P.; Hartmann, R.; Hernandez Pajares, Manuel; Jakowski, Norbert; Kauristie, K.; Orús Pérez, Raul; Prieto Cerdeira, Roberto; Valette, J.J.; Van de Kamp, M.
    IEEE Computer Society
    Presentation's date: 2012-12
    Presentation of work at congresses

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    This paper presents the features of the MONITOR project. This project initiated by ESA/ESTEC aims to increase the knowledge of the ionospheric effects and its impact on GNSS systems during active periods of solar activity. It includes the deployment of a set of GNSS-based ionospheric monitoring receivers worldwide distributed, the development of specific analysis software tools some of them integrated on a common platform, others distributed providing products routinely and a measurement campaign which will last beyond the peak of the current solar cycle

  • Plasmaspheric Electron Content contribution inferred from ground and radio occultation derived Total Electron Content

     Aragon Angel, Maria Angeles; Sanz Subirana, Jaime; Juan Zornoza, Jose Miguel; Hernandez Pajares, Manuel; Altadill, D.
    IEEE International Conference on Communications
    Presentation's date: 2012
    Presentation of work at congresses

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  • Propagation of medium scale traveling ionospheric disturbances at different latitudes and solar cycle conditions

     Hernandez Pajares, Manuel; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime; Aragon Angel, Maria Angeles
    Radio science
    Date of publication: 2012
    Journal article

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    Wide Area RTK: a satellite navigation system based on precise real-time ionospheric modelling  Open access

     Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime; Hernandez Pajares, Manuel; Samson, Jaron; Tossaint, Michel Mathias Maria; Aragon Angel, Maria Angeles; Salazar Hernández, Dagoberto José
    Radio science
    Date of publication: 2012-04-19
    Journal article

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    The Wide Area Real Time Kinematic (WARTK) is an augmentation system concept for multi-frequency users based on precise real-time ionospheric modeling. It is able to provide a high accuracy and integrity GNSS positioning service over continental areas using the infrastructure of a network of permanent ground monitor stations, such as the European Geostationary Navigation Overlay Service (EGNOS) network of Ranging and Integrity Monitoring Stations (RIMS) in Europe. In this way, it allows an additional benefit to be obtained from these reference stations, that is, the network has the potential to support two independent systems: a satellite-based augmentation system, such as EGNOS, and a high-precision positioning service, based on WARTK. Indeed, thanks to the accuracy of the ionospheric corrections provided, WARTK users have available in real-time an extra constraint per satellite between the carrier phase ambiguities, which helps solve them quickly. Once such ambiguities have been solved, the GNSS user obtains navigation accurate to within 20 cm at the 95th percentile (about 10 cm RMS). Moreover, this precise positioning is achieved in a few minutes (with two frequency signals) or in a single epoch, after initial convergence of the tropospheric delay (with three frequency signals), even up to hundreds of kilometers away from the nearest reference station. While previous WARTK research has been devoted to implementing the concept and assessing its feasibility, considering in particular the accuracy achievable, the work reported in this paper focused on consolidating the results by analyzing a large and representative data set, and on deeper analysis of the integrity issue. It was carried out in the context of the Multi-constellation Regional System (MRS) project, within the European Space Agency GNSS Evolution Programme, with the aim of designing a high accuracy service for GPS and/or Galileo. Three months of actual data, from more than 25 permanent GPS stations in Europe, have been processed (some of them as a roving user), for high-, mid- and low-solar cycle conditions (in 2002, 2004 and 2006 respectively). In addition, several ionospheric storms occurred during the selected periods, with Dst values reaching up to −150 nT. Results based on these data show that user domain integrity was maintained for baselines of up to 400 km. At the 95th percentile, the daily horizontal and vertical position errors were 20 and 30 cm, respectively, and the corresponding protection levels were about 1 and 2 m. The convergence time was around 5 minutes with actual GPS constellation data. The benefits of using a multi-constellation system were also studied, with simulated GPS and three-frequency Galileo data, showing that it is possible to reduce the convergence time to a few seconds.

  • GNSS measurement of EUV photons flux rate during strong and mid solar flares

     Hernandez Pajares, Manuel; Garcia Rigo, Alberto; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime; Monte Moreno, Enrique; Aragon Angel, Maria Angeles
    Space weather: the international journal of research and applications
    Date of publication: 2012-12-12
    Journal article

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  • The International GNSS Real-Time Service

     Caissy, Mark; Agrotis, Lukas; Weber, Georg; Hernandez Pajares, Manuel; Hugentobler, Urs
    Gps world
    Date of publication: 2012-06-01
    Journal article

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    Monitoring, tracking and forecasting ionospheric perturbations using GNSS techniques  Open access

     Jakowski, N; Béniguel, Yannick; De Franceschi,, Giorgiana; Hernandez Pajares, Manuel; Jacobsen, Knut Stanley; Stanislawska, Iwona; Tomasik, Lukasz; Warnant, René; Wautelet, Gilles
    Journal of Space Weather and Space Climate
    Date of publication: 2012-12-01
    Journal article

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    The paper reviews the current state of GNSS-based detection, monitoring and forecasting of ionospheric perturbations in Europe in relation to the COST action ES0803 ‘‘Developing Space Weather Products and Services in Europe’’. Space weather research and related ionospheric studies require broad international collaboration in sharing databases, developing analysis software and models and providing services. Reviewed is the European GNSS data basis including ionospheric services providing derived data products such as the Total Electron Content (TEC) and radio scintillation indices. Fundamental ionospheric perturbation phenomena covering quite different scales in time and space are discussed in the light of recent achievements in GNSS-based ionospheric monitoring. Thus, large-scale perturbation processes characterized by moving ionization fronts, wave-like travelling ionospheric disturbances and finally small-scale irregularities causing radio scintillations are considered. Whereas ground and space-based GNSS monitoring techniques are well developed, forecasting of ionospheric perturbations needs much more work to become attractive for users who might be interested in condensed information on the perturbation degree of the ionosphere by robust indices. Finally, we have briefly presented a few samples illustrating the space weather impact on GNSS applications thus encouraging the scientific community to enhance space weather research in upcoming years.

  • Contributions to ionospheric determination with Global Positioning System: solar flare detection and prediction of global maps of Total Electron Content.  Open access

     Garcia Rigo, Alberto
    Defense's date: 2012-12-17
    Universitat Politècnica de Catalunya
    Theses

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    Two research studies have been addressed in this thesis. Both of them are of actual scientific interest and are based on processing GNSS data. The first part of this thesis is devoted to GNSS detection and monitoring of solar flares. The second one is devoted to GNSS prediction of ionospheric Total Electron Content. Regarding the first study, a new solar flare detector called SISTED has been designed and implemented. Its goal is to provide a simple and efficient way of detecting the most number of powerful X-class solar flares in real time operation. In addition, it can send early warning messages to prevent the harmful consequences of the increase of ejected particles from the Sun that may reach the Earth after a solar flare, especially in case of a Coronal Mass Ejection. The main benefit of SISTED regarding other detection techniques is that it does not require data from external providers out of the GNSS community. In addition, it can run in real-time operation and could provide value added data to GNSS users. The results show that SISTED was able to detect up to the 95% of the X-class flares reported by GOES for more than a half solar cycle. Regarding the second study, a new approach to predict Global Ionospheric vertical TEC Maps has been designed and implemented in the context of the IGS Ionosphere Working Group. The motivation to develop a UPC Predicted product was the interest of ESA's SMOS mission. A recent application using UPC Predicted products is the generation of real-time global VTEC maps as background model. In addition, the predicted VTEC maps are used to generate the combined IGS Predicted products. The results obtained in this thesis show that the model performs well when the results are compared with those obtained by the other IGS analysis centers. In addition, applying the prediction model leads to better results than the use of time-invariant ionosphere for two days ahead. In relation with this research, 4 publications in international journals indexed in JCR/ISI have been generated (and another one is under review process), and 7 presentations have been authored in international meetings, among the new UPC predicted product contributing to IGS, and the contribution to two competitive projects funded by the European Space Agency (AGIM and MONITOR).

  • IONO-DECO monthly progress report no 6

     Aragon Angel, Maria Angeles; Hernandez Pajares, Manuel
    Date: 2012-01-02
    Report

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    Integrity monitoring for carrier phase ambiguities  Open access

     Feng, Shaojun; Ochieng, Washington; Samson, Jaron; Tossaint, Michel Mathias Maria; Hernandez Pajares, Manuel; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime; Aragon Angel, Maria Angeles; Ramos Bosch, Pedro; Jofre, Martí
    Journal of navigation
    Date of publication: 2012-01
    Journal article

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    The determination of the correct integer number of carrier cycles (integer ambiguity) is the key to high accuracy positioning with carrier phase measurements from Global Navigation Satellite Systems (GNSS). There are a number of current methods for resolving ambiguities including the Least-squares AMBiguity Decorrelation Adjustment (LAMBDA) method, which is a combination of least-squares and a transformation to reduce the search space. The current techniques to determine the level of confidence (integrity) of the resolved ambiguities (i.e. ambiguity validation), usually involve the construction of test statistics, characterisation of their distribution and definition of thresholds. Example tests applied include ratio, F-distribution, t-distribution and Chi-square distribution. However, the assumptions that underpin these tests have weaknesses. These include the application of a fixed threshold for all scenarios, and therefore, not always able to provide an acceptable integrity level in the computed ambiguities. A relatively recent technique referred to as Integer Aperture (IA) based on the ratio test with a large number of simulated samples of float ambiguities requires significant computational resources. This precludes the application of IA in real time. This paper proposes and demonstrates the power of an integrity monitoring technique that is applied at the ambiguity resolution and positioning stages. The technique has the important benefit of facilitating early detection of any potential threat to the position solution, originating in the ambiguity space, while at the same time giving overall protection in the position domain based on the required navigation performance. The proposed method uses the conventional test statistic for ratio testing together with a doubly non-central F distribution to compute the level of confidence (integrity) of the ambiguities. Specifically, this is determined as a function of geometry and the ambiguity residuals from least squares based ambiguity resolution algorithms including LAMBDA. A numerical method is implemented to compute the level of confidence in real time. The results for Precise Point Positioning (PPP) with simulated and real data demonstrate the power and efficiency of the proposed method in monitoring both the integrity of the ambiguity computation and position solution processes. Furthermore, due to the fact that the method only requires information from least squares based ambiguity resolution algorithms, it is easily transferable to conventional Real Time Kinematic (RTK) positioning.

  • Method, apparatus and system for determining a position of an object having a Global Navigation Satellite System receiver by processing undifferenced data like carrier phase measuurements and external products like ionosphere data

     Hernandez Pajares, Manuel; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime; Samson, Jaron; Tossaint, Michel Mathias Maria
    Date of request: 2012-10-04
    Invention patent

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    Real time Ionospheric determination at global scale  Open access

     Hernandez Pajares, Manuel; Sanz Subirana, Jaime; Garcia Rigo, Alberto
    International Geomatic Week
    Presentation's date: 2011-03-15
    Presentation of work at congresses

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    The global ionospheric determination has been possible in the last 15 years thanks to the availability of a new type of ionospheric sensor with a very high spatial and temporal sampling: the dual-frequency GPS receivers. Indeed, several hundreds of them, worldwide distributed, are freely available, tracking typically 6+ GPS satellites in view, providing at every epoch several thousands of line-of-sight integrated free electron densities (Slant Total Electron Content, STEC). This has allowed in particular to compute and freely distribute global Vertical Total Electron Content (VTEC) maps, in the context of the open- product organization called International GNSS Service (IGS), which applications run from single frequency receivers (accurate mitigation of ionospheric delay), calibration of new altimeters (such as the SMOS mission) up to the potential use for increasing the performance of positioning based on carrier phase measurements. One of the next challenges, in particular in IGS, is computing the global VTEC maps, in real-time, which involves much less permanent receivers, increasing much more the di cult task of interpolating in a realistic way the electron content over large regions with few receivers (south hemisphere, oceans...). In this paper the actual status of the problem will be presented, from the perspective of gAGE/UPC, one of the four IGS Ionospheric Analysis Centers, participating in the Real-Time IGS Pilot Project.

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    Comparative testing of four ionospheric models driven with GPS measurements  Open access

     Feltens, Joachim; Angling, M; Jackson Booth, N; Jakowski, Norbert; Hoque, Mainul; Hernandez Pajares, Manuel; Aragon Angel, Maria Angeles; Orús Pérez, Raul; Zandbergen, R.
    Radio science
    Date of publication: 2011-07-28
    Journal article

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    In the context of the European Space Agency/European Space Operations Centre funded Study “GNSS Contribution to Next Generation Global Ionospheric Monitoring,” four ionospheric models based on GNSS data (the Electron Density Assimilative Model, EDAM; the Ionosphere Monitoring Facility, IONMON v2; the Tomographic Ionosphere model, TOMION; and the Neustrelitz TEC Models, NTCM) have been run using a controlled set of input data. Each model output has been tested against differential slant TEC (dSTEC) truth data for high (May 2002) and low (December 2006) sunspot periods. Three of the models (EDAM, TOMION, and NTCM) produce dSTEC standard deviation results that are broadly consistent with each other and with standard deviation spreads of ∼1 TECu for December 2006 and ∼1.5 TECu for May 2002. The lowest reported standard deviation across all models and all stations was 0.99 TECu (EDAM, TLSE station for December 2006 night). However, the model with the best overall dSTEC performance was TOMION which has the lowest standard deviation in 28 out of 52 test cases (13 stations, two test periods, day and night). This is probably related to the interpolation techniques used in TOMION exploiting the spatial stationarity of vertical TEC error decorrelation.

  • The ionosphere: effects, GPS modeling and the benefits for space geodetic techniques

     Hernandez Pajares, Manuel; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime; Aragon Angel, Maria Angeles; Salazar Hernández, Dagoberto José; Escudero Royo, Miguel
    Journal of geodesy
    Date of publication: 2011-09-10
    Journal article

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  • Global prediction of the vertical total electron content of the ionosphere based on GPS data

     Garcia Rigo, Alberto; Monte Moreno, Enrique; Hernandez Pajares, Manuel; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime; Aragon Angel, Maria Angeles; Salazar Hernández, Dagoberto José
    Radio science
    Date of publication: 2011-12-29
    Journal article

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  • IONO-DECO monthly progress report no 5

     Aragon Angel, Maria Angeles; Hernandez Pajares, Manuel
    Date: 2011-12-01
    Report

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  • MONITORIZADO Y ANALISIS DE LAS CARACTERISTICAS GEOMAGNETICAS Y IONOSFERICAS EN ASJI. MODELADO IONOSFERICO

     Aragon Angel, Maria Angeles; Juan Zornoza, Jose Miguel; Hernandez Pajares, Manuel; Escudero Royo, Miguel; Gonzalez Casado, Guillermo; Rovira Garcia, Adrià; Garcia Rigo, Alberto; Sanz Subirana, Jaime
    Participation in a competitive project

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  • Enhanced Precise Point Positioning (EPPP) for single frequency users

     Hernandez Pajares, Manuel; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime
    Date: 2011-09-01
    Report

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  • IONO-DECO monthly progress report no 4

     Aragon Angel, Maria Angeles; Hernandez Pajares, Manuel
    Date: 2011-10-24
    Report

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  • TN2: definition of improved algorithms in high order ionospheric corrections

     Aragon Angel, Maria Angeles; Hernandez Pajares, Manuel
    Date: 2011-12-07
    Report

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  • MONITOR experimental campaign: preliminary definition document

     Hernandez Pajares, Manuel; Jakowski, N; Angling, M
    Date: 2011-03-10
    Report

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  • Monitor TN2230-40-50

     Hernandez Pajares, Manuel; Garcia Rigo, Alberto
    Date: 2011-11-02
    Report

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  • IONO-DECO monthly progress report no 2

     Aragon Angel, Maria Angeles; Hernandez Pajares, Manuel
    Date: 2011-08-31
    Report

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  • IONO-DECO monthly progress report no 3

     Hernandez Pajares, Manuel; Sanz Subirana, Jaime; Defraigne, P; Bergeot, N; Baire, Q; Aragon Angel, Maria Angeles; Garcia Rigo, Alberto
    Date: 2011-09-30
    Report

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  • MONITOR TN11200 MSTID campaign analysis and modelling

     Hernandez Pajares, Manuel; Garcia Rigo, Alberto
    Date: 2011-10-10
    Report

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  • IonosphericDelay Corrections in GNSS Signals for high precision apllications (IONO-DeCo)

     Hernandez Pajares, Manuel
    Participation in a competitive project

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  • IONO-DECO monthly progress report no 1

     Hernandez Pajares, Manuel; Aragon Angel, Maria Angeles
    Date: 2011-07-25
    Report

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  • Precise real time GPS and GALILEO orbit determination & clock synchronization (PRTODTS)

     Hernandez Pajares, Manuel; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime
    Date: 2011-02-16
    Report

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  • Improvement of retrieved FORMOSAT-3/COSMIC electron densities validated by ionospheric sounder measurements at Jicamarca

     Aragon Angel, Maria Angeles; Liou, Y.-A.; Lee, C.-C.; Reinisch, B. W.; Hernandez Pajares, Manuel; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime
    Radio science
    Date of publication: 2011-09-01
    Journal article

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  • Ground- and space-based GPS data ingestion into the NeQuick model

     Brunini, Claudio; Azpilicueta, F.; Gende, M.; Camilon, E; Aragon Angel, Maria Angeles; Hernandez Pajares, Manuel; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime
    Journal of geodesy
    Date of publication: 2011-03-01
    Journal article

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  • Precisió per al sistema Galileo - Informacions UPC

     Hernandez Pajares, Manuel; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime
    Others' publications about work

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  • Models for atmospheric propagation delays

     Petrie, E.; Hernandez Pajares, Manuel
    Date of publication: 2010
    Book chapter

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  • Integrity monitoring for carrier phase ambiguities

     Feng, Shaojun; Ochieng, Washington; Samson, Jaron; Tossaint, Michel Mathias Maria; Hernandez Pajares, Manuel; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime; Aragon Angel, Maria Angeles; Ramos Bosch, Pedro; Jofre, Martí
    The Institute of Navigation International Technical Meeting
    Presentation's date: 2010-09-23
    Presentation of work at congresses

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  • Wide area real time kinematic: a new augmentation concept towards the definition of a high accuracy and integrity service

     Hernandez Pajares, Manuel; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime; Samson, Jaron; Tossaint, Michel Mathias Maria
    International Beacon Satellite Symposium
    Presentation's date: 2010-07-07
    Presentation of work at congresses

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    A High Precision Positioning Service based in the Wide Area RTK is presented in this work. The integrity and the benefits of the multiconstellation system are also discussed.

  • Network-based High Accuracy Positioning with the GPSTk

     Salazar Hernández, Dagoberto José; Hernandez Pajares, Manuel; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime
    ESA Workshop on Satellite Navigation Technologies
    Presentation's date: 2010-12-09
    Presentation of work at congresses

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  • Access to the full text
    Improvement and validation of retrieved FORMOSAT-3/COSMIC electron densities using Jicamarca DPS  Open access

     Aragon Angel, Maria Angeles; Liou, Y.-A.; C., C Lee; Hernandez Pajares, Manuel; Sanz Subirana, Jaime; Juan Zornoza, Jose Miguel; B.W, Reinisch
    International Beacon Satellite Symposium
    Presentation's date: 2010-06-09
    Presentation of work at congresses

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