Global ETD Search

41	Generalized Bandpass Sampling Receivers for Software Defined Radio Sun, Yi-Ran January 2006 (has links) Based on different sampling theorem, for example classic Shannon’s sampling theorem and Papoulis’ generalized sampling theorem, signals are processed by the sampling devices without loss of information. As an interface between radio receiver front-ends and digital signal processing blocks, sampling devices play a dominant role in digital radio communications. Under the concept of Software Defined Radio (SDR), radio systems are going through the second evolution that mixes analog, digital and software technologies in modern radio designs. One design goal of SDR is to put the A/D converter as close as possible to the antenna. BandPass Sampling (BPS) enables one to have an interface between the RF or the higher IF signal and the A/D converter, and it might be a solution to SDR. However, three sources of performance degradation present in BPS systems, harmful signal spectral overlapping, noise aliasing and sampling timing jitter, hinder the conventional BPS theory from practical circuit implementations. In this thesis work, Generalized Quadrature BandPass Sampling (GQBPS) is first invented and comprehensively studied with focus on the noise aliasing problem. GQBPS consists of both BPS and FIR filtering that can use either real or complex coefficients. By well-designed FIR filtering, GQBPS can also perform frequency down-conversion in addition to noise aliasing reduction. GQBPS is a nonuniform sampling method in most cases. With respect to real circuit implementations, uniform sampling is easier to be realized compared to nonuniform sampling. GQBPS has been also extended to Generalized Uniform BandPass Sampling (GUBPS). GUBPS shares the same property of noise aliasing suppression as GQBPS besides that the samples are uniformly spaced. Due to the moving average operation of FIR filtering, the effect of sampling jitter is also reduced to a certain degree in GQBPS and GUBPS. By choosing a suitable sampling rate, harmful signal spectral overlapping can be avoided. Due to the property of quadrature sampling, the “self image” problem caused by I/Q mismatches is eliminated. Comprehensive theoretical analyses and program simulations on GQBPS and GUBPS have been done based on a general mathematic model. Circuit architecture to implementing GUBPS in Switched-Capacitor circuit technique has been proposed and analyzed. To improve the selectivity at the sampling output, FIR filtering is extended by adding a 1st order complex IIR filter in the implementation. GQBPS and GUBPS operate in voltage-mode. Besides voltage sampling, BPS can also be realized by charge sampling in current-mode. Most other research groups in this area are focusing on bandpass charge sampling. However, the theoretical analysis shows that our GQBPS and GUBPS in voltage mode are more efficient to suppress noise aliasing as compared to bandpass charge sampling with embedded filtering. The aliasing bands of sampled-data spectrum are always weighted by continuous-frequency factors for bandpass charge sampling with embedded filtering while discrete-frequency factors for GQBPS and GUBPS. The transmission zeros of intrinsic filtering will eliminate the corresponding whole aliasing bands of both signal and noise in GQBPS and GUBPS, while it will only cause notches at a limited set of frequencies in bandpass charge sampling. In addition, charge sampling performs an intrinsic continuous-time sinc function that always includes lowpass filtering. This is a drawback for a bandpass input signal. / QC 20100921 Radio receivers Software Defined Radio (SDR) uniform/nonuniform sampling reconstruction bandpass sampling noise aliasing sampling jitter generalized bandpass sampling complex signal processing complex FIR and IIR filter design Switched-Capacitor (SC) circuit Electrical engineering Elektroteknik
42	Impact des transformations algorithmiques sur la synthèse de haut niveau : application au traitement du signal et des images Ye, Haixiong 20 May 2014 (has links) (PDF) La thèse porte sur l'impact d'optimisations algorithmiques pour la synthèse automatique HLS pour ASIC. Ces optimisations algorithmiques sont des transformations de haut niveau, qui de part leur nature intrinsèque restent hors de porter des compilateurs modernes, même les plus optimisants. Le but est d'analyser l'impact des optimisations et transformations de haut niveau sur la surface, la consommation énergétique et la vitesse du circuit ASIC. Les trois algorithmes évalués sont les filtres non récursifs, les filtres récursifs et un algorithme de détection de mouvement. Sur chaque exemple, des gains ont été possibles en vitesse et/ou en surface et/ou en consommation. Le gain le plus spectaculaire est un facteur x12.6 de réduction de l'énergie tout en maitrisant la surface de synthèse et en respectant la contrainte d'exécution temps réel. Afin de mettre en perspective les résultats (consommation et vitesse), un benchmark supplémentaire a été réalisé sur un microprocesseur ST XP70 avec extension VECx, un processeur ARM Cortex avec extension Neon et un processeur Intel Penryn avec extensions SSE. Synthèse de haut niveau Transformation de haut niveau Filtre FIR Filtre IIR Sigma Delta Filtre morphologique Catapult-C Métaprogrammation Traitement du signal Traitement des images
43	Design of digital filters using genetic algorithms Ahmad, Sabbir U. 17 December 2008 (has links) In recent years, genetic algorithms (GAs) began to be used in many disciplines such as pattern recognition, robotics, biology, and medicine to name just a few. GAs are based on Darwin's principle of natural selection which happens to be a slow process and, as a result, these algorithms tend to require a large amount of computation. However, they offer certain advantages as well over classical gradient-based optimization algorithms such as steepest-descent and Newton-type algorithms. For example, having located local suboptimal solutions they can discard them in favor of more promising local solutions and, therefore, they are more likely to obtain better solutions in multimodal problems. By contrast, classical optimization algorithms though very efficient, they are not equipped to discard inferior local solutions in favour of more optimal ones. This dissertation is concerned with the design of several types of digital filters by using GAs as detailed bellow. In Chap. 2, two approaches for the design of fractional delay (FD) filters based on a GA are developed. The approaches exploit the advantages of a global search technique to determine the coefficients of FD FIR and allpass-IIR filters based on the so-called Farrow structure. The GA approach was compared with a least-squares approach and was found to lead to improvements in the amplitude response and/or delay characteristic. In Chap. 3, a GA-based approach is developed for the design of delay equalizers. In this approach, the equalizer coefficients are optimized using an objective function based on the passband filter-equalizer group delay. The required equalizer is built by adding new second-order sections until the desired accuracy in terms of the flatness of the group delay with respect to the passband is achieved. With this approach stable delay equalizers satisfying arbitrary prescribed specifications with the desired degree of group-delay flatness can easily be obtained. In Chap. 4, a GA-based approach for the design of multiplierless FIR filters is developed. A recently-introduced GA, called orthogonal GA (OGA) based on the so-called experimental design technique, is exploited to obtain fixed-point implementations of linear-phase FIR filters. In this approach, the effects of finite word length are minimized by considering the filter as a cascade of two sections. The OGA leads to an improved amplitude response relative to that of an equivalent direct-form cascade filter obtained using the Remez exchange algorithm. In Chap. 5, a multiobjective GA for the design of asymmetric FIR filters is proposed. This GA uses a specially tailored elitist nondominated sorting GA (ENSGA) to obtain so-called Pareto-optimal solutions for the problem at hand. Flexibility is introduced in the design by imposing phase-response linearity only in the passband instead of the entire baseband as in conventional designs. Three objective functions based on the amplitude-response error and the flatness of the group-delay characteristic are explored in the design examples considered. When compared with a WLS design method, the ENSGA was found to lead to improvements in the amplitude response and passband group-delay characteristic. In Chap. 6, a hybrid approach for the design of IIR filters using a GA along with a quasi-Newton (QN) algorithm is developed. The hybrid algorithm, referenced to as the genetic quasi-Newton (GQN) algorithm combines the flexibility and reliability inherent in the GA with the fast convergence and precision of the QN algorithm. The GA is used as a global search tool to explore different regions in the parameter space whereas the QN algorithm exploits the efficiency of a gradient-based algorithm in locating local solutions. The GQN algorithm works well with an arbitrary random initialization and filters that would satisfy prescribed amplitude-response specifications can easily be designed Digital signal processing digital filter optimization evolutionary algorithm genetic algorithm FIR filter IIR filter fractional delay delay equalizer multiplierless FIR filter
44	Uso de Aisladores Sísmicos Para Edificios Multifamiliares. Caso De Estudio: Edificio Multifamiliar Residencial Hungría Fernández Loayza, Jannet, Quispe Vilca, Albert Dante, Vargas Salazar, Raúl Daniel, Lucero Rojas, Katherine Reyna, Alva Jiménez, Alfonso Renato 26 October 2020 (has links) Nuestro proyecto busca demostrar que se puede mejorar el desempeño sísmico de las edificaciones empleando aisladores sin afectar la rentabilidad del proyecto. Para ello, se evaluó aplicarlo en el proyecto “Residencial Hungría” el cual se trata de un edificio multifamiliar de 12 departamentos y 10 estacionamientos distribuidos en 4 pisos y un semisótano respectivamente. Se modifico la configuración original del proyecto y se incluyó un sistema de aisladores de base con núcleo de plomo con el fin de comparar la rentabilidad entre ambos proyectos (Original y modificado con aisladores). Los resultados obtenidos en la primera etapa muestran que ante un número reducido de pisos (04 pisos) la rentabilidad del proyecto modificado con aisladores es menor a la original, sin embargo, luego de evaluar múltiples opciones, se obtuvo que a partir de 07 pisos tiene un VAN de S/ 172,077 un TIR de 24 % mayor al COK que es de 20%. Sabemos que en la Filosofía y Principios del Diseño Sismorresistente contenidos en la Norma E.030 del Reglamento Nacional de Edificaciones se reconoce que dar protección completa frente a todos los sismos no es técnica ni económicamente factible para la mayoría de las estructuras, es por ello por lo que el uso de los aisladores está enfocado principalmente a estructuras del sector salud y educación. Con esto proyecto queremos propiciar la aplicación de aisladores a más proyectos de edificaciones y viviendas multifamiliares, verificando que, si puede ser rentable económicamente para el constructor, lo cual beneficiaría la demanda desatendida de la población que requiere una vivienda más segura y con mejor desempeño ante un sismo, y que minimice los costos de reparación, muertes y damnificados ante un eventual movimiento sísmico de alto impacto aun teniendo que invertir un porcentaje adicional en la compra del inmueble. / This research demonstrate that the seismic performance of buildings can be improved by using isolators without affecting the profitability of the project. For this, it was evaluated in the "Residential Hungria" project, which is a multifamily building with 12 apartments and 10 parking spaces distributed in 4 floors and a semi- basement, respectively. The original configuration of the project was modified and a system of base insulators with lead core was included in order to compare the profitability between both projects (Original and modified with insulators). The results obtained in the first stage show that with a reduced number of floors (04 floors) the profitability of the project modified with insulators is lower than the original one, however, after evaluating multiple options, it was obtained that from 07 floors it have a NPV of S / 172,077 an IIR of 24% higher than the COK which is 20%. We know the Philosophy and Principles of Earthquake Resistant Design contained in Standard E.030 of the National Building Regulations, it is recognized that providing complete protection against all earthquakes is not technically or economically feasible for most structures, which is why isolators is mainly focused on structures in the health and education sectors. With this project we want to promote the application of insulators to more projects of buildings and multifamily housing, verifying that, it can be economically profitable for the builder, which would benefit the unattended demand of the population that requires a anti seismic building prepared for an earthquake, minimizes repair costs, deaths and victims in eventual high-impact seismic movement even having to invest an additional percentage in the purchase of the property. / Trabajo de investigación Aislador sísmico Edificio multifamiliar VAN (valor neto actual) TIR (tasa interna de retorno) COK (costo de oportunidad de capital Seismic Isolator, Multi-Family Building NPV (Net Present Value) IIR (internal rate of return) COK (opportunity cost of capital)
45	MEMS-Laser-Display-System / MEMS Laser Display System Specht, Hendrik 19 October 2011 (has links) (PDF) In der vorliegenden Arbeit werden die im Zusammenhang mit der Strahlablenkung stehenden Systemaspekte der auf MEMS-Scanner basierenden Laser-Display-Technologie theoretisch analysiert und aus den Ergebnissen die praktische Implementierung eines Laser-Display-Systems als Testplattform vorgenommen. Dabei werden mit einem Ansatz auf Basis zweier 1D-Scanner und einem weiteren Ansatz mit einem 2D-Scanner zwei Varianten realisiert. Darüber hinaus erfolgt die Entwicklung eines bildbasierten Multiparametertestverfahrens, welches sowohl für den Test komplettierter Strahlablenkeinheiten bzw. Projektionsmodule als auch zum umfassenden und zeiteffizienten Test von MEMS-Scannern auf Wafer-Level geeignet ist. Mit diesem Verfahren erfolgt eine Charakterisierung der zwei realisierten Varianten des Laser-Displays. Ausgehend von den Eigenschaften des menschlichen visuellen Systems und den daraus resultierenden Anforderungen an das Bild sowie einer systemtheoretischen Betrachtung des mechanischen Verhaltens von MEMS-Scannern bildet die Ansteuersignalerzeugung für den resonanten Betrieb der schnellen und den quasistatischen Betrieb der langsamen Achse einen Schwerpunkt. Neben dem reinen digitalen Regler- bzw. Filterentwurf sowie mehreren Linearisierungsmaßnahmen beinhaltet dieser auch die Herleitung einer FPGA-basierten Videosignalverarbeitung zur Konvertierung von Scannpattern, Zeitregime und Auflösung mit einer entsprechenden Synchronisierung von Strahlablenkung und Lasermodulation. Auf Grundlage der daraus resultierenden Erkenntnisse über den Zusammenhang zwischen Scanner-/Systemparametern und Bildparametern werden Testbild-Bildverarbeitungsalgorithmus-Kombinationen entwickelt und diese, angeordnet in einer Sequenz, mit einem Kalibrierverfahren zu einem Testverfahren für MEMS-Scanner vervollständigt. Die Ergebnisse dieser Arbeit entstanden im Rahmen von industriell beauftragten F&E-Projekten und fließen in die andauernde Fortführung des Themas beim Auftraggeber ein. Laserdisplay Mikrospiegel MOEMS Videosignalverarbeitung Scannpattern Rasterscann Lissajous Positionsregelung FIR-Filter IIR-Filter resonanter Betrieb quasistatischer Betrieb Testverfahren Wafer-Level laser display micro mirror MEMS MOEMS image quality resolution distortion linearity video processing scaling scan pattern line scan Lissajous system model position control phase locked loop FIR IIR filter resonant drive quasi-static drive wafer level test image processing ddc:003 ddc:620 ddc:629 MEMS Bildqualität Auflösung Verzeichnung Linearität Skalierung Systemmodell Phasenregelung Nichtrekursives Filter Rekursivfilter Test Bildverarbeitung
46	Praktické ukázky zpracování signálů / Practical examples of signal processing Hanzálek, Pavel January 2019 (has links) The thesis focuses on the issue of signal processing. Using practical examples, it tries to show the use of individual signal processing operations from a practical point of view. For each of the selected signal processing operations, an application is created in MATLAB, including a graphical interface for easier operation. The division of the thesis is such that each chapter is first analyzed from a theoretical point of view, then it is shown using a practical demonstration of what the operation is used in practice. Individual applications are described here, mainly in terms of how they are handled and their possible results. The results of the practical part are presented in the attachment of the thesis.
47	MEMS-Laser-Display-System: Analyse, Implementierung und Testverfahrenentwicklung Specht, Hendrik 20 May 2011 (has links) In der vorliegenden Arbeit werden die im Zusammenhang mit der Strahlablenkung stehenden Systemaspekte der auf MEMS-Scanner basierenden Laser-Display-Technologie theoretisch analysiert und aus den Ergebnissen die praktische Implementierung eines Laser-Display-Systems als Testplattform vorgenommen. Dabei werden mit einem Ansatz auf Basis zweier 1D-Scanner und einem weiteren Ansatz mit einem 2D-Scanner zwei Varianten realisiert. Darüber hinaus erfolgt die Entwicklung eines bildbasierten Multiparametertestverfahrens, welches sowohl für den Test komplettierter Strahlablenkeinheiten bzw. Projektionsmodule als auch zum umfassenden und zeiteffizienten Test von MEMS-Scannern auf Wafer-Level geeignet ist. Mit diesem Verfahren erfolgt eine Charakterisierung der zwei realisierten Varianten des Laser-Displays. Ausgehend von den Eigenschaften des menschlichen visuellen Systems und den daraus resultierenden Anforderungen an das Bild sowie einer systemtheoretischen Betrachtung des mechanischen Verhaltens von MEMS-Scannern bildet die Ansteuersignalerzeugung für den resonanten Betrieb der schnellen und den quasistatischen Betrieb der langsamen Achse einen Schwerpunkt. Neben dem reinen digitalen Regler- bzw. Filterentwurf sowie mehreren Linearisierungsmaßnahmen beinhaltet dieser auch die Herleitung einer FPGA-basierten Videosignalverarbeitung zur Konvertierung von Scannpattern, Zeitregime und Auflösung mit einer entsprechenden Synchronisierung von Strahlablenkung und Lasermodulation. Auf Grundlage der daraus resultierenden Erkenntnisse über den Zusammenhang zwischen Scanner-/Systemparametern und Bildparametern werden Testbild-Bildverarbeitungsalgorithmus-Kombinationen entwickelt und diese, angeordnet in einer Sequenz, mit einem Kalibrierverfahren zu einem Testverfahren für MEMS-Scanner vervollständigt. Die Ergebnisse dieser Arbeit entstanden im Rahmen von industriell beauftragten F&E-Projekten und fließen in die andauernde Fortführung des Themas beim Auftraggeber ein. info:eu-repo/classification/ddc/003 ddc:003 info:eu-repo/classification/ddc/620 ddc:620 info:eu-repo/classification/ddc/629 ddc:629
48	Využití reverberátorů pro úpravu akustiky prostoru / Using reverberators to modify space acoustics Pavlikovský, Vladislav January 2013 (has links) This diploma thesis deals with adjusting the reverberation time of enclosed spaces. It is divided into two thematic areas. The first thematic area deals with active systems that adjust the reverberation time, with a stronger focus on usage of reverberators to simulate secondary spaces. The second thematic area is the implementation of reverberators and their fundamental building blocks in Matlab.
49	Hlukoměr pro embedded systémy / Sound level meter for embedded systems Stejskal, Tomáš January 2015 (has links) The aim of this work is the design and implementation of a sound level meter for emdedded systems. It is designed sound level meter sensor. This sensor includes a microphone, microphone preamplifier and ADC. This sensor is connected to a development kit STM32F4 Discovery, where sound is processed. It is processed filtration, time weighting, calculation of sound leve and loudness weighting. The sound level is then sent via the serial communication USART. This thesis includes a theoretical analysis of noise and its human perceptions. It also describes the development platform used.
50	Zlomkooktává analýza akustických signálů / Fractional-Octave Analysis of Acoustic Signals Ryšavý, Marek January 2016 (has links) The diploma thesis is focused on design and optimalization of digital octave and fraction-octave band filters. This thesis describe the behavior of filters in systems with fixed point arithmetics and investigate the impact of quantization coefficients for frequency response of filter. Filters, whitch has been designed, are implemented into simple software in C. Designed filters are in accordance with standard IEC 61260.

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