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Descripción
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| This Ph. D. thesis belongs to the specific framework of using radar sensors aboard UAVs (Unmanned Aerial Vehicles). The interest in UAV systems started twenty years ago, because they do not need a pilot on board. This advantage has several interesting consequences: UAVs can be smaller and consume lower energy than manned aircrafts, because UAVs do not need a cockpit and are less weighted. They can carry out dangerous missions, in hostile environments, and under critical weather conditions, without risking pilot¿s life. Furthermore, UAVs overcome all the human being limits, flying at very high altitude, with very high accelerations, and for long periods of time. To use radar aboard UAVs, on one hand, it is interesting that the radar has a good performance, i.e., a high resolution, a high sensitivity, a high dynamic range, a large range, and a wide functionality. On the other hand, it is interesting to reduce the size, volume, weight, and power consumption of the sensor. The use of radar systems aboard UAVs has a wide range of promising military and civilian applications: reconnaissance, surveillance, mapping, vegetation and terrain analysis, tactical management, waste tracking, minefield detection, disasters and crisis management, etc. The main advantage is that radar sensors are all-weather, and can operate with reduced visibility, during the night, with smoke or fog. The main objective of this Ph. D. thesis is the analysis of the drawbacks associated to the use of radars aboard UAVs, proposing novel solutions to overcome them. The Ph. D. thesis has been divided into five chapters: The first chapter defines the objectives of this Ph. D. thesis, and justifies its content and structure. Furthermore, this chapter includes an introduction to UAV systems, which contains their definition, classification, characteristics and the main radar applications aboard them. The second chapter contains a study of millimeter-wave frequency modulated continuous wave radars (FMCW), because they are very attractive to be installed in UAVs. Also, this chapter shows a description about the SEIISM system, which is a millimeter-wave FMCW radar system that has been developed to prove the feasibility of the techniques proposed in this Ph. D. thesis. The third chapter deals with the problem of reducing the number of antennas in high resolution continuous wave radars. Different alternatives are analyzed to operate a FMCW radar system with only one antenna, and a novel solution, which overcomes the drawbacks under some constraints, is proposed. The fourth chapter studies the acquisition subsystem of high resolution radars. This subsystem generates a high throughput at the output of the analog-to-digital converter. Different alternatives are analyzed, and a novel solution, which fulfils the main constraints of radars aboard UAVs, is proposed. Finally, the fifth chapter analyzes the use of high resolution synthetic aperture radar (SAR) aboard UAVs. A digital SAR processing chain, which is suitable for UAV operation, is proposed. | |
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Internacional
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Si |
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ISBN
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Tipo de Tesis
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Doctoral |
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Calificación
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Sobresaliente cum laude |
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Fecha
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05/06/2009 |