Yuzo Iano

Resumo-Este artigo visa descrever e comparar as principais técnicas presentes na literatura para a avaliação objetiva de qualidade de vídeo no padrão H.264, aplicada a sistemas de transmissão de TV Digital. A avaliação objetiva idealmente permite a obtenção de uma métrica de qualidade automática, dispensando o uso de observadores humanos. Essa avaliação pode ser feita em laboratório ou em tempo-real, e nesses casos utilizam referência total ou reduzida, respectivamente. A grande maioria das técnicas de avaliação objetiva presentes na literatura foi testada em sequências no padrão MPEG2. Porém, os novos padrões de TV Digital, usados em diversas aplicações, utilizam atualmente o padrão H.264, que podem gerar diferentes tipos de degradação, principalmente quando a relação sinal ruído (SNR – Signal to Noise Rate) do canal de transmissão está em seu limite para permitir a recuperação da informação. Neste artigo, são apresentadas as principais técnicas de avaliação de qualidade objetiva u...

ABSTRACT The light field cameras are becoming a new trend in photography. They have characteristics that could overcome some problems present in surveillance videos, like refocusing and depth estimation. The main advantage is that the light field camera allows focus reconstruction, increasing the depth of field. However, these new cameras require different processing power and storage than conventional cameras. In this paper, it is shown how these cameras work and how they could be employed in surveillance. Images of a standard surveillance camera versus the plenoptic camera are compared and some issues about the design of the light field camera are discussed. Finally, we compare the performance of video compression standards applied to plenoptic image sequences. The power signal noise ratio results show that MPEG4 is the best choice.

The Single Frequency Network (SFN) allows a single TV channel to cover a great area in the same frequency, increasing the spectrum efficiency and signal quality. In this case, all the programs are re-multiplexed into a Transport Stream (TS) and distributed to the re-transmitter stations. The Integrated Digital Services Broadcasting-Terrestrial (ISDB-T) has been projected to operate in SFN, and uses

This work intends to demonstrate the improvements applied in the integrated system digital broadcasting-terrestrial (ISDB-T). The turbo processing has been considered one of the most promising techniques for the improvement of performance in communication systems. The use of turbo convolutional codes (TCCs) combined with soft decision demapping is proposed for reduction of signal to noise rate (SNR) threshold at reception.

In this paper the improvement in the performance obtained by a Time Interleaving applied to DVB-T scheme are analyzed in impulsive noise environments. The performance is evaluated in terms of bit error rate probability for Oms, 100 ms and 200 ms of time interleaving length. The results are compared with the standard DVB-T (digital video broadcasting - terrestrial) evaluated on

Solar energy is the raw material and main source for several applications of renewable energy systems; thus, knowledge about the intensity of solar irradiation is essential for efficiency of these systems. Electric energy sources capable of meeting the growing demands of society with minimal impacts to the environment and high efficiency have been object of research in the last decade. In this context, the conversion of sunlight into electricity through photovoltaic cells has become one of the most encouraged and used resources in the world. However, the most unpredictable factor, which hampers capturing solar irradiation, preventing a proper conversion of sunlight into electricity, is the presence of clouds in the sky. Many methods of tracking and prediction of irradiation were proposed to increase efficiency in the production of energy by photovoltaic cells. This article presents an updated review on the mechanisms used for tracking and irradiation prediction, and their respective methods. It begins with a brief review on photovoltaic systems and classification of its mechanisms. Then, it presents a detailed overview on the evolution of mechanisms and their corresponding methods for tracking and irradiation prediction. Finally, the authors conclude with an analysis of performance efficiency of the mechanisms and their corresponding methods presented, describing the pros and cons of the most significant proposals for tracking and irradiation prediction.