Modulation Formats
Mostrando 1-11 de 11 artigos, teses e dissertações.
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1. Link Optimization and Performance Analysis of a 40 Gbps DQPSK Modulated Ultra DWDM System with 32 Orthogonally Polarized channels
Abstract The demand for higher speed at a lesser transmission cost per bit resulted in growth of optical networks with improved spectral efficiency even at narrower channel spacing. Incorporation of multilevel modulation formats in DWDM system led to the exploration of the 25 GHz channel grid, popularly known as Ultra Dense Wavelength Division Multiplexed (U
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2016-12
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2. All-optical cryptography through spectral amplitude and delay encoding
All-optical data encryption is a promising technology that could lead communication systems to an unprecedented degree of security. In this paper we use computer simulations to systematically investigate a new all-optical cryptography technique that is bit-rate independent and transparent to modulation formats. Encryption encompasses signal spectral slicing
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2013-12
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3. Effect of Fiber Optic Chromatic Dispersion on the Performance of Analog Optical Link with External Modulation Aiming at Aerospace Applications
ABSTRACT: This paper addresses the subject of fiber optic chromatic dispersion effect on the performance of analog optical link with dual-drive electro-optic Mach-Zehnder modulator, aiming at aerospace applications. Thus, a direct detection link model that emphasizes both the modulator electronic drive and the dispersion characteristic of a linear optical fi
J. Aerosp. Technol. Manag.. Publicado em: 2013-06
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4. Estudos de sistemas OFDM para comunicações ópticas / Studies OFDM systems for optical communications
The development of digital modulation formats in optical communications systems is considered to be a promising way to increase the spectral efficiency and to combat the effects of signal degradation in optical fiber without changing the infrastructure already deployed. In this context, the technique called OFDM (orthogonal frequency division multiplexing) e
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 03/10/2012
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5. Análise de redes ópticas de alta velocidade baseadas na tecnologia CDMA e códigos bidimensionais (comprimento de onda/tempo) / Analysis of high-speed optical wavelength/time CDMA networks
Esta dissertação apresenta uma análise realista de redes OCDMA (acesso múltiplo por divisão de código) baseadas em dois formatos de modulação distintos, qual sejam, OOK (chaveamento on-off) e PPM (modulação por posição de pulso). O desempenho desses formatos de modulação sob dois esquemas de codificação bidimensionais (2-D), isto é, pulsos �
Publicado em: 2010
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6. Study of special modulation formats for optical communication / Estudo de formatos especiais na modulação digital para comunicações ópticas
This MSc thesis investigates optical modulation formats as an alternative to the use of the traditional intensity binary format NRZ (Non-return-to-zero). Those formats, classified as advanced, represent one of the key technologies aimed to enable the high data volume and broadband, demanded by the present telecommunication market, with cost reduction of tran
Publicado em: 2009
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7. POLARIZATION OF LIGHT CONTROL IN MONOMODE OPTICAL FIBERS AND APLICATIONS / CONTROLE DA POLARIZAÇÃO DA LUZ EM FIBRAS ÓPTICAS MONOMODO E APLICAÇÕES
The control of polarization state, as well as a control of all states of polarization of a light signal travelling through a singlemode optical fiber, is performed using different schemes. The polarization control of the signal in a DWDM channel is performed using reference signals in lateral channels in real time. A polarization encoded quantum key distribu
Publicado em: 2009
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8. Caracterização espectral e avaliação de desempenho para formatos avançados de modulação digital optica em 40 Gb/s / Spectral characterization and performance evaluation for advanced digital optical modulation formats at 40 Gb/s
This work compares the performance of four feedforward carrier recovery architectures in coherent QPSK and 8-PSK receivers, with polarization multiplexing and differential decoding. We focused on the scenarios showing an SNR imbalance between orthogonal polarizations, as in PDL impaired systems. Using Monte Carlo simulations, we observed that the proposed jo
Publicado em: 2009
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9. Modelagem de redes CDMA-PON baseadas em técnicas de cancelamento paralelo e códigos corretores de erros / Modeling of CDMA-PON networks using parallel interference cancellation and error correcting codes techniques
The advent of new services offered to end users, such as the so called triple play, which consists in the simultaneous traffic of voice, video, and data through the same communication infrastructure, has been pushing telecom operators towards providing adequate bandwidth as well as quality of service. This has brought the spotlight to passive optical network
Publicado em: 2009
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10. ESQUEMAS DE MODULAÇÃO PARA DISTRIBUIÇÃO QUÂNTICA DE CHAVES COM CODIFICAÇÃO DE FREQÜÊNCIA / MODULATION SCHEMES FOR FREQUENCY CODED QUANTUM KEY DISTRIBUTION
Quantum cryptography has been proposed as a solution to the cryptographic key distribution problem with absolute security guaranteed by the principles of quantum mechanics. Through this scheme it is possible to find out whether a spy tried to eavesdrop on the transmission, which was impossible to discover using classical transmission techniques. In this work
Publicado em: 2005
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11. The use of oligodeoxynucleotide probes in chaotrope-based hybridization solutions.
Hybridization solutions containing chaotropes may be used to modulate the thermal stability (Tm or Td) of oligodeoxynucleotide (ODN) duplexes or hybrids over a 90 degrees C range. Modulation of Td allows formulation of hybridization solutions that permit ambient temperature hybridization using most combinations of probe length, probe composition, target type