Non Linear Channel
Mostrando 13-24 de 64 artigos, teses e dissertações.
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13. Analise experimental das aplicações de codigos corretores de erro em sistemas de comunicações opticas
This work presents an experimental analysis on the use of error correcting codes in optical communication systems, specifically by means of the Forward Error Correction (FEC) technique. Two electronic modules were designed and assembled during the experimental stages of the work - a coding and decoding module, which uses the Reed-Solomon RS (255,241) code, a
Publicado em: 2003
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14. Desconvolução autodidata concorrente para equalização de canais de comunicações
The Constant Modulus Algorithm {CMA) is recognized as the most widely used algorithm in blind channel equalization practice. However, the CMA cost function exhibits local minima, which often leads to ill-convergence. This thesis proposes the Concurrent Equalizer, in which a Least Mean Square (LMS) equalizer operates cooperatively with a CMA equalizer, contro
Publicado em: 2001
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15. Desenvolvimento e analise de novos algoritmos preditivos para equalização cega
In this work, the blind equalization of a communication channel will be considered. The work will focus on the discussion of blind equalization techniques that are based on linear prediction theory. These are called predictive techniques for blind equalization. Firstly, the need for an equalizer in a communication system will be discussed, as well as the adv
Publicado em: 1997
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16. Modelagem bidimensional da injeção de agua em reservatorios heterogeneos
This work studies the application of strearntube theory joined with a two-porosity linear model in heterogeneous reservoirs under injection of a incompressible wetting fluid and the production of a non-wetting fluid. It was considered that the streamlines are fixed and there is no flow between each channel. Gravity was neglected and the imbibition phenomena
Publicado em: 1996
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17. Equalização adaptativa em sistemas radio-digitais : das tecnicas em frequencia a teoria da desconvolução autodidata
Equalization in microwave digital-radio transmission systems is dealt with under a transient and steady-state point of view. The c1assical theory of digital transversal equalization is revisited and complemented concerning the c1assical aspects of mean square error minimization (MSEM) and zero forcing (ZF), and also in the proposal of an algorithm for the ad
Publicado em: 1992
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18. Filtragem adaptativa com restrições lineares por minimos quadrados
The basic problem of linear constrained filtering consists In searching ao optimal filter whose parameters are subject to a set of linear equations. For transversal structures, the optimal coefficients In the mean-square sense are given by the Wlener-Hopf equations. The introduction of constraints leads to a modified solution, obtained by the Lagrange multip
Publicado em: 1991
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19. A PERFORMANCE ANALYSIS OF PSK SYSTEMS WITH SEVERAL CARRIERS SHARING A CAMMON LINEAR CHANNEL / ANÁLISE DE DESEMPENHO DE SISTEMAS PSK COM MÚLTIPLAS PORTADORAS COMPARTILHANDO UM MESMO CANAL NÃO LINEAR
A análise de desempenho de sistemas de comunicações nos quais um grande número de portadoras, de diferentes tipos e níveis de potência, acessam uma mesma não-linearidade, esbarra, inicialmente, na dificuldade de se determinar, com precisão e tempo de computação aceitável, a distribuição de potência do ruído de intermodulação gerado. O proble
Publicado em: 1988
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20. ANÁLISE DE DESEMPENHO DA MODULAÇÃO MULTI-H EM CANAIS NÃO LINEARES LIMITADOS EM FAIXA / PERFORMANCE OF MULTI-H MODULATION OVER NON-LINEAR, BAND LIMITED CHANNELS
Error correcting codes have been used in power limited digital communication systems to improve the system error probability performance. This performance improvement is obtained at the price of an expanded occupied bandwidth or a lower rate of information transmission. Integrated coding and modulation techniques allow an increased performance without this b
Publicado em: 1988
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21. DESEMPENHO DE SISTEMAS QAM QUATERNÁRIOS EM CANAIS NÃO LINEARES / PERFORMANCE OF QAM QUATERNARY SYSTEMS IN NONLINEAR CHANNELS
Several 4-QM digital modulation systems recently proposed in the literature for application to nonlinear channels are studied and their performances are compared through computer simulation. Efficient techniques to estimate performance parameters from the simulated digital signals are developed and used for extensive computations of power spectrum and error
Publicado em: 1986
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22. SIMULATION PROGRAM FOR DIGITAL TRANSMISSION SYSTEMS WITH PHASE MODULATION THROUGH NON-LINEAR CHANNELS / SIMULAÇÃO DE SISTEMAS DE TRANSMISSÃO DIGITAL COM MODULAÇÃO DE FASE ATRAVÉS DE CANAIS NÃO LINEARES
Como alternativa ao cálculo do desempenho através de métodos analíticos, é desenvolvido um programa de simulação de sistemas de transmissão digital com modulação de fase (PSK, Off-set PSK e MSK) e recepção coerente através de canais não lineares. Representando os sinais através de suas envoltórias complexas o programa permite simular qualquer
Publicado em: 1983
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23. EFEITOS DE INTERMODULAÇÃO EM SISTEMAS SCPC/FM COM ATIVAÇÃO POR VOZ / INTERMODULATION EFFECTS IN THE TRANSMISSION OF VOICE-ACTIVATED SCPC/FM CARRIERS THROUGH A NONLINEAR REPEATER
Em um sistema satellite SCPC/FM, um grande número de portadoras é amplifcado simultaneamente pela TWT do satélite. Devido à característica não linear desta válvula, surgem, na saída, sinais espúrios resultantes do batimento das diversas freqüências e que interferem nas portadoras desejadas.Desta forma para um bom dimensionamento de um sistema SCPC
Publicado em: 1978
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24. Activation of a novel non-selective cation channel by alloxan and H2O2 in the rat insulin-secreting cell line CRI-G1.
1. Alloxan and its auto-oxidation product hydrogen peroxide (H2O2) irreversibly depolarize insulinoma cells by opening a non-selective cation channel. The channel opened is characterized by a linear current-voltage relation with a conductance of approximately 70 pS and very slow kinetics (of the order of seconds). 2. Cells are protected against the alloxan-i