Low Bit Rate
Mostrando 1-12 de 17 artigos, teses e dissertações.
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1. Transmission of a 20 Gb/s NRZ OOK signal throughout a 390 km fiber link and a cascade of 11 x 50 GHz filters and 9 x EDFAs
This paper presents a qualitative analysis of the impact caused by fiber propagation effects and by a cascade of optical filters, designed for 10 Gb/s NRZ OOK transmission, and optical amplifiers on a 20 Gb/s NRZ OOK optical signal traveling a 390 km fiber link. The choice for such bit rate and modulation format has been driven by the 50 GHz bandwidth of the
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2011-06
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2. Codificação de vídeo : priorização do menor custo de codificação na otimização em taxa-distorção
This research work proposes two new video compression strategies, aiming at typical low bit rate video applications using rate-distortion (RD) optimized algorithms. The proposed strategies are implemented on an H.264 video encoder, which has high computational complexity due mainly to the large number of coding modes available. Two approaches are presented f
Publicado em: 2009
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3. Um sistema simplicado para tranmissão de dados em rede de energia eletrica : concepção do circuito, prototipo e proposta de integração / A simplified system for power line data communication : circuit design, prototype and integration proposal
It was developed in this work a circuit for power line data communication - PLC that enable low speed data transmission in a circuit topology that enable a future integration. The built prototype was elaborated with discrete components and exhibits a compatible operation with a typical PLC circuit. The coupling circuits with the mains wires are extensively d
Publicado em: 2009
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4. 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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5. Study of the audio coding algorithm of the MPEG-4 AAC standard and comparison among implementations of modules of the algorithm
Audio coding is used to compress digital audio signals, thereby reducing the amount of bits needed to transmit or to store an audio signal. This is useful when network bandwidth or storage capacity is very limited. Audio compression algorithms are based on an encoding and decoding process. In the encoding step, the uncompressed audio signal is transformed in
Publicado em: 2007
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6. Proposta de um esquema de codificaÃÃo de vÃdeo a baixas taxas de transmissÃo para comunicaÃÃes mÃveis celulares / Proposal for low bit rate video coding for cellular phones communications
Very low bit rate coding below 64 kbit/s will be an important issue in forthcoming visual services such as videophone and multimedia systems. The trend of increasing interest in, and demand for, mobile phone, interactive TV and multimedia services, has led to significant acceleration of video coding research worldwide. This paper introduces and presents simu
Publicado em: 2006
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7. Códigos de Bloco com Decodificação Turbo Adaptados às Especificações do Padrão DVB-RCT / Códigos de Bloco com Decodificação Turbo Adaptados às Especificações do Padrão DVB-RCT
Product codes formed by serial concatenation of single parity check component codes are used in this thesis to fulfill the requirements of coding rate and block length expressed by the standard known as DVB-RCT (Digital Video Broadcasting - Return Channel Terrestrial). This standard describes the parameters of the physical layer for a digital TV wireless ret
Publicado em: 2004
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8. O uso do EDGE nos sistemas celulares em direÃÃo à 3 geraÃÃo
Nowadays, mobile communications market is being driven by the need of data services. Among the systems of the first and second generation (1G and 2G), GSM (Global Mobile System) is undoubtedly the most used in all world for voice applications, however, it continues offering data services with low bit rates, which in parallel with the low capacities of the sy
Publicado em: 2002
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9. Modulação multiportadora codificada por bloco para radioenlaces digitais em microondas com linha de visada
The availability of line-of-sight (LOS) microwave digital systems which work at high transmission rates such as 155 Mb/s, may be strongly limited by frequency-selective fading effects. The main countermeasure techniques against the fading are equalizations, diversity and error control coding. Under adverse geoclimatic conditions, the path length and/or the t
Publicado em: 2002
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10. CODIFICACIÓN DE VOZ A TASAS MEDIAS ABAJO DE 2 KB/S / CODIFICAÇÃO DE VOZ A TAXAS MÉDIAS ABAIXO DE 2 KB/S / SPEECH CODING AT AVERAGE RATES BELOW 2KB/S
Esta disertación propone algoritmos para codificaciones de voz a tasas medias en torno de 1,2 Kb/s. Se propone un esquema de cuantización vectorial predictiva, con desempeño superior a los esquemas previamente descritos en la literatura. Este esquema se evalúa en canal con o sin ruido. Se examinan detectores eficientes de período fundamental y de sueño
Publicado em: 2001
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11. Manejo florestal : impactos ecologicos de diferentes niveis de remoção e os impactos de sua sustentabilidade
The objective ofthis study was to evaluate an experiment offorest management established in 1980 at the Reserva Natural da Vale do Rio Doce, and monitored during a period of 20 years. The forest was exploited according to various levels of basal area remotion, totaling 9 treatments, including the control, in which no interference was made and the clearcut, w
Publicado em: 2001
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12. MATHEMATICAL AND EXPERIMENTAL APPROACHES IN SHAPE-ADAPTATIVE VIDEO CODING / ABORDAGENS MATEMÁTICAS E EXPERIMENTAIS EM CODIFICAÇÃO DE VÍDEO ADAPTATIVA À FORMA
This thesis investigates shape adaptative coding of arbitrarily shaped segments. The texture and contour coding efficiency is discussed and solutions to tackle the associated problems are proposed. The presented methods are evaluated using standard image sequences. A mathematical approach for shape-adaptative transforms using linear operators is developed, f
Publicado em: 2000