IONOSPHERE

Author: MOHINO HARRIS ELSA.
Year: 2004.
University: COMPLUTENSE DE MADRID [www.ucm.es].
Place of defense: FACULTAD DE CIENCIAS FÍSICAS.
Place of preparation: FACULTAD DE CIENCIAS FÍSICA, UNIVERSIDAD COMPLUTENSE DE MADRID.

Summary: Systems Global Navigation Satellite are today embracing a tool whose wide range of applications, covering areas as diverse as transport and finance, is expanding fast. However, in order to ensure their smooth operation and high accuracy is necessary to understand the various sources of error affecting the system so we can mitigate them. The thesis has been devoted to one of these sources of error, the presence of atmospheric layer coductura as ionosphere, which alters the spread of satellite signals and thus the actions that they take place. In particular, the thesis addresses the problem of the delay inosférico for timely and differential positioning receivers for a frequency. The two main objectives of the thesis are: 1-To examine the effect of the ionosphere in the positioning of a receiver of a single frequency. The thesis makes special hincipié to conduct the study on cordenadas and not just on the line connecting the receiver to the satellite. For this reason it is divided into two distinct parts, the first on the effect on the positioning isolated and the second on the vector differential. 2-Mitigate this effect. Along the thesis shows several strategies to reduce the impact of this source of error in both types of positioning. In the case of algorithms absolute position is the result of correct observations by ionospheric models classic versions with embedded GPS data and differential correction (DGPS). Likewise, it shows a technique that allows users with recipients who do not register comments perform these same correciciones on the final standings with the only restriction to know what satellites were visible in every era. Finally, to reduce the impact iconosférico regarding determinations of differential positioning, is a technique based on empelo multi estadiciones reference.

Author: CUETO SANTAMARÍA MARTA.
Year: 2004.
University: COMPLUTENSE DE MADRID [www.ucm.es].
Place of defense: FACULTAD DE CIENCIAS FÍSICAS.
Place of preparation: FACULTAD DE CIENCIAS FÍSICAS. UNIVERSIDAD COMPLUTENSE DE MADRID.

Summary: The radiation from the sun that hits the Earth's atmosphere produces, among other effects, ionization of gases that comprise it, giving rise to the ionosphere, as well as the generation of variations in refractive index to find the electromagnetic waves that pass through. The importance of the ionosphere and an adequate characterization of its electron density has soared as has been realizing its influence on satellite communications. In particular, the development of Systems Global Navigation Satellite (GNSS) has made the study of the influence of ionospheric plasma in the transmission of electromagnetic waves despite being a key issue in developing these techniques. The scope of the global positioning systems GNSS satellite (GPS, GLONASS and Galileo future) is very broad, ranging from the geodynamics until synching electronic devices. However, the more extensive use of these systems is navigation (That positioning in real time) through a single receiver GNSS (single frequency). The dispersion suffering GNSS signal to cross the ionosphere is the main cause that limits the accuracy of positioning: single frequency receivers can not remove this effect but compensate with a proper ionospheric model, hence the importance of any effort to an improvement in the characterization of the values of electron density and the electronic content that give the models. Europe has not been outside the development and positioning systems, in addition to commissioning the system EGNOS (and European Geostationary Navigation Overlay Servicie), has opted for a constellation capable of securing a European system for autonomous navigation satellite with a usage civilian. This is the aim of the Galileo system, under definition and development and which is expected to be operational in 2008. Currently, the values of electron density above the maximum electron density of the layer F2 calculated using empirical ionospheric models like NeQuick and the International Reference Ionosphere IRI deviate significantly from the values obtained experimentally. To ensure that these models are more realistic, it is vital to introduce them in a better modeling of the plasmasfera, and the design of an adequate transition region between the two. To this end, this paper develops improved model ionospheric NeQuick by including the formulation plasmasférica proposal in the model empirical Gallagher, proven useful beyond the 1300 km altua. Examine to turn the differences between the theoretical model NeQuick original and the model NeQuick & Gallagher, and will assess the performance of both models using data from total content vertically (vTEC) and experimental values of the peak of the region Ionospheric F2. The experimental values of electron density plasmasférica they adjusted the parameters of empirical model of Gallagher relate to the years 1981 and 1982. Such time series of experimental data is far from reaching a complete solar cycle, which can be seen as a temporary lapse advisable for proper modeling of the plasmasfera. Therefore, it is possible that the behavior of this model is not the best. On the other hand, it is likely that the region's model NeQuick above the maximum layer F2 can be better defined by the variation of one of the model parameters NeQuick & Gallagher, using values vTEC derived from GPS measurements and processed properly . This work pl 8 antea a 243 to route optimization model NecQuick & Gallagher, a mathematician by adjusting certain parameters contained in their design, using experimental values of vTEC.

Author: ORUS PEREZ RAÒL.
Year: 2005.
University: POLITÉCNICA DE CATALUÑA [www.upc.edu].
Place of defense: ETSETB. MODUL -B3-CAMPUS NORD.
Place of preparation: EPSC, EDIFICI CC1 Campus CASTELLDEFELS.