This thesis deals with the general issue of geographic information system GRASS distributed under the licence GNU GPL. It introduces the system itself and its possibilities as well as describes the terminology used in the Geography scientific sector. It also can be use as a simple handbook for teaching GIS.

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Made available in DSpace on 2014-06-11T19:22:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-07-31Bitstream added on 2014-06-13T18:08:14Z : No. of bitstreams: 1 holzschuh_ml_me_prud.pdf: 1897806 bytes, checksum: 49dcd938d6b1fba152b414f9f4c978cc (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A ocultação, um fenômeno pelo qual um corpo celeste deixa de ser visto em razão da sobreposição de um outro, começou a ser usada para estudar a atmosfera de outros planetas há vários anos. Com o advento dos satélites artificiais GPS (Global Positioning System), em conjunto com os satélites LEO (Low Earth Orbiting), surge a Rádio Ocultação GPS (ROGPS), abrindo-se novas perspectivas para as pesquisas sobre o clima e previsão de tempo. Na RO GPS, os sinais que são enviados pelo satélite GPS e recebidos no satélite LEO sofrem os efeitos da troposfera e da ionosfera ao atravessarem a atmosfera terrestre, afetando a fase e a amplitude das ondas dos sinais envolvidos. A propagação do sinal sofre refração formando uma linha curva entre o satélite transmissor e o receptor, o que permite calcular diferentes índices de refratividade, os quais carregam informações da composição da atmosfera terrestre. A partir de perfis desses índices de refratividade é possível extrair perfis de temperatura, umidade e pressão atmosférica na troposfera, além da distribuição na densidade de elétrons na ionosfera terrestre. Vários trabalhos foram realizados para verificar a qualidade dos perfis atmosféricos obtidos com o emprego do satélite CHAMP (Challenging Minisatellite Payload of Geophysical Research and Application), um satélite LEO, em diversas regiões do globo. Nesse trabalho, objetiva-se investigar e implementar a técnica de ocultação GPS, bem como avaliar a qualidade de perfis de temperatura obtidos com o satélite CHAMP sobre a América do Sul, comparando-os com perfis de radiossondas e perfis provenientes da condição inicial do modelo de Previsão Numérica de Tempo (PNT). A implementação da recuperação de um perfil da atmosfera foi realizada utilizando o código C/A para o cálculo do ângulo de curvatura e o parâmetro de impacto, cujos valores aproximados foram 0,043° e 6381 km, respectivamente. / The occultation, phenomenon in which a celestial body in not seen because of the superposition of another one, started being used several years ago to study the atmosphere of other planets. With the advent of GPS (Global Positioning System) satellites, together with the LEO (Low Earth Orbit) satellites, the GPS Radio Occultation (GPS-RO) arises, in order to obtain new perspectives in studies related to climate and weather forecast. In GPS-RO, the signals sent by the GPS satellite and received by the LEO satellite are disturbed by the ionosphere and troposphere while cross the terrestrial atmosphere, this affects the phase and the amplitude from the involved signals. The signals propagation is affected by refraction, this generates a bending angle between the transmitter and receiver satellites, allowing computing different refractivity index, which carry information about the terrestrial atmosphere composition. Using these profiles of refractivity index is possible to extract profiles of temperature, humidity, atmospheric pressure in the troposphere, and to obtain the electronic density distribution in terrestrial ionosphere. Several works were realized to verify the quality of atmospheric profiles obtained using the CHAMP (Challenging Minisatellite Payload of Geophysical Research and Application) satellite, LEO satellite, in several regions of the globe. In this research the goal is to investigate and implement the GPS occultation technique, and additionally to evaluate the quality of the temperature profiles obtained by CHAMP satellite over the South of America, comparing them with the RSO (Radiosonde) profiles and with the profiles obtained by the initial condition of Numeric Weather Prediction (NWP) model.

The diploma thesis studies accuracy of cheap GPS devices intended for mobile mapping in the landscape. Methodlogy for testing the accuracy of two GPS devices was established on the base of studied literature and apllied to two different GPS devices. The first device is PDA ASUS A639 connected by Bluetooth with external GPS reciever Navilock BT-338 and the second one is PDA ASUS A639 using its inbuilt GPS chipset. The result of testing is firstly comparison of accuracy of these two GPS devices and secondly the elements, which influnce their accuracy the most. The database of results is large enough to make some general conclusions concerning the accuracy of different GPS devices and their usage in the process of mobile mapping.

Using observations from the Global Positioning System (GPS) satellites to determine a three dimensional (3-D) geodetic control network are considered. The repeatability of individual baselines and 3-D vector closures are examined, in order to investigate refraction effects on GPS networks. The effect on GPS baselines of a height bias in the reference point's coordinates is also investigated. A least squares adjustment program is developed and used to obtain a single consistent set of 3-D coordinates for the Tygerberg Test Network (TTN). The results of two GPS processing packages are compared by means of a conformal transformation. It is concluded that single frequency measurements produce better results than the ionospheric free observable on short baselines. Furthermore, a standard atmospheric model shows an improvement over the Marini model to account for tropospheric refraction.

This thesis deals with an introduction of new functionalities in communication via IP Multimedia Subsystem (IMS) at the beginning. There are described functions of each part and introduced protocols which are used by this system. Thesis presents the method of positioning with Global Positioning System (GPS) together with methods for the distance measuring of two points on the Earth. Services provided by IMS are developed in Service Development Studio which is shortly mentioned too. The developed service is divided into two parts: a client side part and a server side part, which is formed like a servlet. This program component, which is running on server is mentioned at the end of teoretical part. The procedure of service creating, setup and functions are in description of the created service, which provides informations based on geographical coordinates to user, is described after the teoretical part.

This thesis is focused on utilization of GPS navigation especially in agricultural pra-xis. The main goal of this work is putting on and controlling of agricultural equipment at resolution of anti-erosion measures. These measures are reaction to the so called antiero-sive regulation. In the theoretical part is shortly described GPS system and the work with geodates. Then there are described methods limiting water erosion of soil. Sub-sequently there is shortly described a problem of erosion measures and complex of the information necessary to the utilization of GPS navigation while fighting with this issue. In the practical part of this work was formed the method for the creation of anti-erosion measures. According to this method was subsequently developed the procedure to ad-justment SEO DPB. This method was subsequently apllied and tested in POOSLAVÍ Nová Ves, agricultural kooperative. At the conclusion of the work is evaluated by ma-nagement on the thus modified DPB and then there are described problems that occured while creating these anti-erosion measures. For that reason are drawn recommendations for putting on and controlling of agricultural equipment at resolution anti-erosion mea-sures.

The thesis deals with the possibility of fixing the position of the machine through the use of satellite systems for agriculture. It is divided into theoretical and practical part. The theoretical part includes three chapters, which are described most famous satellite navigation systems which include GPS systems GLONAS, Galileo and Beidou. Most attention is paid to the GPS system, the work is described its history, functions, each system accuracy, influences affecting the precision guidance signals and correcting their mistakes. Error correction is divided into DGPS, RTK and VRS RTK systems. This is followed by describing the indicators that affect the accuracy of broadcast signals from space satellites. The last theoretical part describes the benefits of parallel guidance of machinery in agriculture in collaboration with boundary management. The practical part is focused on field trail measure, which described the impact of working conditions stand for precision guidance for land assessment and evaluation of the measurement results.

Total electron content (TEC) data measured from ground-based GPS receivers is compared to HF backscatter from ionospheric irregularities obtained by Super Dual Auroral Radar Network (SuperDARN) radars.  We present the first observations of a recurrent region of anomalous enhanced TEC at mid-latitudes over North America and attempt to characterize its frequency of occurrence.  Next, we examine the relationship of convection electric fields to the formation of a polar cap tongue of ionization (TOI) from mid-latitude plumes of storm enhanced density (SED) during a geomagnetic storm on 26 September 2011.  A channel of high density F region plasma was transported from the dayside ionosphere and into the polar cap by enhanced convection electric fields extending to mid-latitudes.  After the solar wind IMF conditions quieted and the dayside convection electric fields retreated to higher latitudes, an SED was observed extending to, but not entering, the dayside cusp region.  The source mechanism (enhanced electric fields) previously drawing the plasma from mid-latitudes and into the polar cap was no longer active, resulting in a fossil feature which persisted for several hours as it elongated in magnetic local time. Finally, we discuss ground surface effects on the HF backscatter observed by four SuperDARN radars. Monthly ground scatter occurrence rates are calculated for comparison with Arctic sea ice boundaries derived from satellite observations, showing reduced backscatter from regions covered by ice. / Master of Science

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