Rf Modulation
Mostrando 1-12 de 19 artigos, teses e dissertações.
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1. An Analytical Solution for Fiber Optic Links with Photonic-Assisted Millimeter Wave Upconversion Due to MZM Nonlinearities
Abstract Photonic-assisted technique employed in the generation of stable and high-purity signals in the millimeter wave band has been investigated using dual-parallel Mach-Zehnder modulator. Indeed, this type of generation performs a high order RF multiplier, whose operation principle steams out from the nonlinear characteristic of the external modulators.
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2017-03
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2. Interval training based on ventilatory anaerobic threshold increases cardiac vagal modulation and decreases high-sensitivity c-reative protein: randomized clinical trial in coronary artery disease
Background: Autonomic dysfunction and inflammatory activity are involved in the development and progression of coronary artery disease (CAD), and exercise training has been shown to confer a cardiovascular benefit. Objective: To evaluate the effects that interval training (IT) based on ventilatory anaerobic threshold (VAT) has on heart rate variability (H
Braz. J. Phys. Ther.. Publicado em: 09/10/2015
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3. Conversor CC/CA de alta freqüência baseado em inversores ressonantes com comutação seqüencial para excitação de uma tocha indutiva a plasma térmico
This work describes the study, the analysis, the project methodology and the constructive details of a high frequency DC/AC resonant series converter using sequential commutation techniques for the excitation of an inductive coupled thermal plasma torch. The aim of this thesis is to show the new modulation technique potentialities and to present a technologi
Publicado em: 2010
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4. Geração de sinais de RF por mistura de harmonicas de portadoras opticas moduladas em amplificadores opticos a semicondutor / RF signal generation by mixing harmonics of modulated optical carriers in semiconductor optical amplifiers
The gain-crossed properties of semiconductor optical amplifiers are experimentally investigated here. It was observed that optically feed-backed saturated amplifiers could achieve similar performance as that of cascaded amplifiers, offering up to 10 dB gain to two 8-nm-appart modulated optical carriers. Due to saturation the amplifier gain mechanism is alter
Publicado em: 2008
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5. Front-end of the Brazilian Digital TV system. / Sintonizador-demodulador para o sistema brasileiro de TV digital.
O sintonizador-demodulador de RF, também chamado de Front End, é definido de uma forma geral como sendo o conjunto ou módulo que está entre a antena e o sistema digital. Para um receptor isto inclui todos os filtros, amplificadores de baixo ruído, misturadores e demoduladores, necessários para processar o sinal modulado recebido na antena, demodulá-lo
Publicado em: 2008
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6. CaracterizaÃÃo de dispositivos hÃbridos microondas/fotÃnica
Esta dissertaÃÃo apresenta um estudo experimental do link microondas/fotÃnica, que neste trabalho foi chamado de enlace analÃgico Ãptico. Este tipo de enlace à usado para transmitir informaÃÃes em fibras Ãpticas, as quais oferecem vÃrias vantagens quanto à quantidade de informaÃÃo que pode ser transmitida, manuseio, perdas e custo em relaÃÃo �
Publicado em: 2008
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7. A constraint-based model to support electronic TV network design
Electronic Television Network Design is well established when electronic physics concepts and computer techniques joint trough mathematical equations and geometrics concepts, to represent real effects. Even though, the two fields have significant different concepts. This research has as objective to propose one approach constraint-based data model, to suppor
Publicado em: 2008
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8. Longitudinal phase space density manipulation in synchrotron light sources / Manipulação da densidade eletronica no espaço de fase longitudinal em fontes de luz sincrotron
Esta tese investiga a dinâmica longitudinal não-linear do feixe de elétrons de alta intensidade circulante no anel de armazenamento do Laboratório Nacional de Luz Síncrotron (LNLS). Em particular, analisamos os efeitos sobre os modos de oscilação coerentes instáveis e sobre as características de equilíbrio dos pacotes de elétrons decorrentes da ma
Publicado em: 2007
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9. AnÃlise e resultados experimentais de sistemas de distribuiÃÃo quÃntica de chaves usando fÃtons isolados e estados coerentes mesoscÃpicos. / Theorical analysis and experimental results of quantum key distribution systems using single-photons and mesoscopic coherent states
In this dissertation it is realized a study about quantum key distribution (QKD) in optical networks. Initially, a review of the theory of quantum key distribution and some of its implementations with strongly attenuated coherent states, as well a review of an optical system for physical encryptation using mesoscopic coherent states are realized. Following,
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 13/09/2006
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10. Receptor super-regenetativo (900 MHz) implementado em tecnologia CMOS 0,35 mu m / Super regenerative receiver (900 MHz) in 0,35 mu m
O objetivo deste trabalho é propor uma topologia de receptor adequada para atender as exigências de uma rede de sensores sem fio, onde baixo consumo e baixo custo de fabricação são fundamentais.A topologia escolhida foi a do receptor super-regenerativo realizado em tecnologia CMOS 0,35Km e operando em 900 MHz. O chip foi montado e testado numa placa de
Publicado em: 2006
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11. Identification of the Alfvén wave resonances in the TCABR tokamak by the microwave reflectometry
The experimental results on the Alfvén mode structure identification by the microwave reflectometry in TCABR tokamak are presented. The knowledge of the spatial spectrum of the excited waves is crucial for optimization of Alfvén wave plasma heating and noninductive current drive scenarios in tokamak plasmas. No less important is the possibility to use the
Brazilian Journal of Physics. Publicado em: 2004-12
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12. Desenvolvimento de um tomógrafo de ressonância magnética: integração e otimização. / Development of a magnetic resonance tomograph: integration and improvement.
The present work describes the development of a Magnetic Resonance Tomography system to be used for medical diagnostics. It is based on commercially available subsystems such as used as in commercial MRI equipments. The main contributions to the project were: the development of fill up electronics and software needed to turn the acquired hardware into a MR T
Publicado em: 1995