Cancelamento de eco em telefonia IP

AUTOR(ES)

Euler Mendes Rachid

DATA DE PUBLICAÇÃO

2004

RESUMO

The objetive of this thesis is the study about echo cancellation in a IP telephony, providing a new technique better than the actual one employed in gateways. This technique takes account the fact that the delay in an IP network is variable. This work presents an overview on adaptive lter subject, following an study about echo cancellation in a PSTN network, it explains the functionality of some devices such as attenuators, echo suppressors and echo cancellers. The relation between echo control and the measured voice quality is presented. The echo path models presented in ITU-T G.168 recommendation are used to test the conventional echo canceller performance. For this purpose the ERLE (Echo Return Loss Enhancement) and the convergency time are measured. Finally, simulation results for the new cancellation method are presented and discussed in details

ASSUNTO(S)

telefone filtros adaptativos ruido eletrico comunicação interpessoal garantia de qualidade processamento de sinais

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