Navegando por Assunto "Linhas digitais de assinantes"

Agora exibindo 1 - 3 de 3

Acesso aberto (Open Access)
Implementação em software da codificação de canal em ADSL: um estudo de caso sobre os efeitos do ruído impulsivo na transmissão de vídeo
(Universidade Federal do Pará, 2011-03-25) CORRÊA, Fernanda Regina Smith Neves; KLAUTAU JÚNIOR, Aldebaro Barreto da Rocha; http://lattes.cnpq.br/1596629769697284; PELAES, Evaldo Gonçalves; http://lattes.cnpq.br/0255430734381362
This work describes the implementation in software of the channel coding used in the ADSL standard. The theory of channel coding is described, as well as the channel coding implemented in the Software Modem ADSL using the development environment Ptolemy II. The implementation of a impulsive noise model is also presented. To ensure that the implementation meets the ADSL standard, tests using the DSL systems analyzer TraceSpan are described. This work also presents an application example of the Software Modem ADSL, characterized by a study case on the e ects of impulsive noise in the video transmission, analyzing the impact of some parameters of channel coding in the correction of errors.
Acesso aberto (Open Access)
Medidas para caracterização de crosstalk e ruído impulsivo em sistemas DSL
(Universidade Federal do Pará, 2009) NUNES, Diogo Lobato Acatauassú; KLAUTAU JÚNIOR, Aldebaro Barreto da Rocha; http://lattes.cnpq.br/1596629769697284
The current work presents tests and laboratory experiments to measure crosstalk and impulsive noise in DSL systems, which are of great importance for the improvement and development of this technology. The crosstalk study was focused in a measurements campaign of short-length cables operating at extremely high frequencies. The results were used in the transmission rates calculation of DSL systems operating in this type of unexplored scenario. The impulsive noise study focused on the development of a telephone line digitizing system allowing real measurements of the noise.
Acesso aberto (Open Access)
Método de otimização não-linear para impor PSDs arbitrárias em modems DSL: análise estatística e prática
(Universidade Federal do Pará, 2011-01-25) ABRAHIM, Harney Edison Pereira; KLAUTAU JÚNIOR, Aldebaro Barreto da Rocha; http://lattes.cnpq.br/1596629769697284
This work aims to present a method to solve the mapping problem between the theoretical dynamic spectrum management (DSM) solutions and the commercial DSL modems transmitting power spectrum densities (PSDs) parameters. The method uses an integer codi ed genetic algorithm (GA) to solve the problem. The GA is responsible for nding the ttest parameters that represents an arbitrary PSD, under the restrictions imposed by the actual DSL equipments and standards. This work shows a comparative study of the proposed method with another concurrent. A statistics study of the proposed method considering the average, standard deviation and con dence interval is done. Finally, two di erent laboratory setups are presented. One of them to PSD measurement and other to use in transfer function measurements. Both setups can be reused in other works.