Made available in DSpace on 2014-06-11T19:22:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-10-31Bitstream added on 2014-06-13T19:08:04Z : No. of bitstreams: 1 pereira_fc_me_ilha.pdf: 2358565 bytes, checksum: 4d967db226fa8d0d0a3f5e5792731645 (MD5) / O grupo de estudos do Laboratório de Optoeletrônica (LOE) da FEIS-UNESP trabalha há vários anos na área de interferometria óptica. A expressão geral da transmissão (razão entre o retardo de fase e a tensão aplicada) de um modulador eletro-óptico de intensidades é idêntica à expressão do sinal fotodetectado na saída de um interferômetro de dois feixes. Em 2012, um novo método de detecção interferométrica de fase óptica foi desenvolvido no LOE, sendo denominado de método de segmentação do sinal amostrado (SSA). Este método é imune ao fenômeno de desvanecimento, é capaz de mensurar o valor da diferença de fase quase-estática entre os braços do interferômetro, consegue medir o tempo de atraso entre o estímulo e a resposta, é pouco sensível ao ruído eletrônico, apresenta excelente resolução, tem ampla faixa dinâmica, permite caracterizar dispositivos não-lineares e pode operar com uma grande variedade de sinais periódicos não-senoidais. Beneficiando-se dessas informações, promoveu-se uma adaptação do método SSA para fins de se implementar um sensor óptico de tensão (SOT) elevada, a base do efeito eletro-óptico linear em cristais de niobato de lítio. O trabalho desenvolvido nesta dissertação se insere nesta linha de pesquisa, porém, ao contrário de trabalhos pregressos realizados no LOE, onde o sinal fotodetectado era amostrado por um osciloscópio digital e processado em microcomputador, agora, empregam-se processadores digitais de sinais (DSPs) tanto para amostrar quanto processar o sinal. Operando-se com a placa eZdspF28335, de ponto-flutuante, foram executadas medições da forma de onda de sinais de alta tensão, em 60 Hz e com elevado conteúdo de harmônicas superiores. Desta forma, gráficos de linearidade (relação entre o retardo induzido versus tensão elétrica aplicada)... / The Optoelectronic Laboratory (OEL) research group has been working for many years in the optical interferometry field. The general expression for the transmission (phase shift and drive voltage ratio) of an electro optic amplitude modulator is identical to the photo-detected signal at the output of a two-beam interferometer. In 2012, a new interferometry method for optical phase detection was developed at OEL, named Sampled Piece-Wise Signal (SPWS) method. This method, which is immune to fading, is used to measure the value of the quasi-static optical phase difference between the arms of the interferometer. The method has small influence from to electronic noise, provides excellent resolution, has a wide dynamic range, and allows the characterization of non-linear devices. Furthermore, the SPWS method is used to measure the time delay between stimulus and response and may operate with a wide variety of non-sinusoidal periodic signals. In this work the SPWS method is adjusted aiming the high voltage measurement by using an optical voltage sensor (OVT) based on the linear electro-optic effect in lithium niobate crystals. Unlike previous studies realized at OEL, where the photo-detected signal was acquired by a digital oscilloscope and processed with a microcomputer, a digital signal processor (DSPs) is employed for both signal acquisition and processing. Measurements of high voltage signal waveforms, at 60 Hz and with higher harmonic content, were performed using the eZdspF28335 card, with floating-point operation. Thus, OVT linearity (induced phase shift versus drive voltage) and frequency response curves were obtained. The spectrum of the high voltage signal was calculated, and hence, parameters such as THD (Total Harmonic Distortion) and IHD (Individual Harmonic Distortion) could be determined. Two different OVT configurations were tested... (Complete abstract click electronic access below)

M.Ing. (Electrical and Electronic Engineering) / Power line communications have been in use since the early 1900‟s. The early use of this technology was mostly found within utility companies where it was used for intra telephonic service over the electrical distribution network. This technology has evolved remarkably to include not only low voltage medium and high voltage electric network but it has also extended to home automation and network. Literature on power line communications has pointed out major hindrances such as cable characteristics, impedance variations and noise signals from various sources. Most importantly, noisy characteristics of power line channels make it difficult to transmit information data in an effective and reliable way. More often data transmitted through power line channels is corrupted by three main types of noise, the background noise, the impulse noise and the permanent frequency disturbances. Consequently, researchers have focused on the optimum use of power line channel through combining channel coding and modulation schemes. In this study, we have, through simulations and practical experimentations, investigated the performance of a new mapping technique called “frequency mapping” over power line channel. The study material began with reviews of channel coding, modulation and permutation codes schemes. Further we presented through computer simulation, the inherent benefit of using permutation codes obtained through construction technique. Secondly, we detailed the use of Hadamard transform to produce frequency sequences. In reality, sign changes, drawn from observing Hadamard matrix and Walsh functions, were conceptualised as frequencies from which frequency sequences were produced. This technique termed “frequency mapping” showed effectiveness against narrow band noise in simulation environment. The study closed with an experimental verification of this new technique through custom designed communication system on a real power line channel where we observed a net BER performance gain when frequency sequences are ordered through Hadamard transform.

One of the fastest developing areas in the entertainment industry is digital animation. Television programmes and movies frequently use 3D animations to enhance or replace actors and scenery. With the increase in computing power, research is also being done to apply these animations in an interactive manner. Two of the biggest obstacles to the success of these undertakings are control (manipulating the models) and realism. This text describes many of the ways to improve control and realism aspects, in such a way that interactive animation becomes possible. Specifically, lip-synchronisation (driven by human speech), and various modeling and rendering techniques are discussed. A prototype that shows that interactive animation is feasible, is also described. / Mr. A. Hardy Prof. S. von Solms

M. Tech. (Electrical & Electronic Engineering) / In this research we compare conventional data acquisition system (DAS) with the embedded data acquisition systems. The performance specifications of 4 different types of DAQ cards are drawn up with special emphasis made on the following parameters: Slew rate, settling time, relative accuracy and system noise. These parameters are taken from 2 conventional DAS and then compared to those taken from 2 embedded data acquisition systems under the same electrical conditions. The embedded DAQ system’s hardware was built using the PIC Microcontroller interfaced to the Digital to Analog Convertors (DAC). MPLAB C18 is used to create a program which communicates with the embedded DAQ system, to transmit generated signals. National Instrument's LabView is used to create a program which communicates with the conventional DAQ system, to acquire external generated signals and retransmit the signals. In most cases the performance of conventional and embedded are close, but one of the embedded DAS seem to be unstable at high frequencies.

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With the prevalence of smartphones, pedestrians and joggers today often walk or run while listening to music. Since they are deprived of auditory stimuli that could provide important cues to dangers, they are at a much greater risk of being hit by cars or other vehicles. We start this research into building a wearable system that uses multichannel audio sensors embedded in a headset to help detect and locate cars from their honks and engine and tire noises. Based on this detection, the system can warn pedestrians of the imminent danger of approaching cars. We demonstrate that using a segmented architecture and implementation consisting of headset-mounted audio sensors, front-end hardware that performs signal processing and feature extraction, and machine-learning-based classification on a smartphone, we are able to provide early danger detection in real time, from up to 80m distance, with greater than 80% precision and 90% recall, and alert the user on time (about 6s in advance for a car traveling at 30mph). The time delay between audio signals in a microphone array is the most important feature for sound-source localization. This work also presents a polarity-coincidence, adaptive time-delay estimation (PCC-ATDE) mixed-signal technique that uses 1-bit quantized signals and a negative-feedback architecture to directly determine the time delay between signals in the analog inputs and convert it to a digital number. This direct conversion, without a multibit ADC and further digital-signal processing, allows for ultra low power consumption. A prototype chip in 0:18μm CMOS with 4 analog inputs consumes 78nW with a 3-channel 8-bit digital time-delay output while sampling at 50kHz with a 20μs resolution and 6.06 ENOB. We present a theoretical analysis for the nonlinear, signal-dependent feedback loop of the PCC-ATDE. A delay-domain model of the system is developed to estimate the power bandwidth of the converter and predict its dynamic response. Results are validated with experiments using real-life stimuli, captured with a microphone array, that demonstrate the technique’s ability to localize a sound source. The chip is further integrated in an embedded platform and deployed as an audio-based vehicle-bearing IoT system. Finally, we investigate the signal’s envelope, an important feature for a host of applications enabled by machine-learning algorithms. Conventionally, the raw analog signal is digitized first, followed by feature extraction in the digital domain. This work presents an ultra-low-power envelope-to-digital converter (EDC) consisting of a passive switched-capacitor envelope detector and an inseparable successive approximation-register analog-to-digital converter (ADC). The two blocks integrate directly at different sampling rates without a buffer between them thanks to the ping-pong operation of their sampling capacitors. An EDC prototype was fabricated in 180nm CMOS. It provides 7.1 effective bits of ADC resolution and supports input signal bandwidth up to 5kHz and an envelope bandwidth up to 50Hz while consuming 9.6nW.

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Underwater networks are a field that has been gathering attention. Land-based methods of network construction from discovery to advanced routing are all well established. Due to the unique constraints of operating in an underwater environment, many of these tried-and-true approaches need modification if they function at all. Peer discovery and lowlevel networking have been dealt with by previous research. In this thesis we describe and evaluate eight possible routing schemes with different system-knowledge requirements. We show that with a minimal set of information it is possible to achieve near-optimal results with energy costs considerably lower than centralized optimal algorithms. We demonstrate this by constructing and evaluating a custom simulation environment in MATLAB. This is implemented in a mixed procedural and array-centric approach. Simulated networks are structured on a line topology. All nodes a spaced along the horizontal axis at a random depth. It is assumed that neighbor-discovery has been completed before the simulation starts, and all nodes have access to a global list of connected neighbors. We demonstrate the effectiveness of distributed algorithms in an ideal environment, leading to the conclusion that near-optimal results can be achieved with local information only.

The major objective of this report is to present information regarding the design, construction, and testing of the Digital Oscilloscope Peripheral which allows the IBM Personal Computer (IBM PC) to be used as both a digital oscilloscope and a spectrum analyzer. The design and development of both hardware and software are described briefly; however, the test results are analyzed and discussed in great detail. All documents including the circuit diagrams, program flowcharts and listings, and user manual are provided in the appendices for reference. Several different products are referred to in this report; the following lists each one and its respective company: IBM, XT, AT, and PS/2 are registered trademarks of International Business; Machines Corporation.; MS-DOS is a registered trademark of Microsoft Corporation.; and Turbo Basic is a registered trademark of Borland International, Inc.