引言在通信系统中，例如IP电话、可视电话及免提数字蜂窝电话系统中，回声和噪声会严重影响通信质量。

IntroductionIn the communication systems, echo and noise will seriously affect speech communication quality, such as IP telephone, videophone and hand-free digital cell phone systems etc.

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摘要：介绍了一种基于数字电视网络可视电话的原理和实现方案。

Abstract: the theory and implementation of visual phone based on digital TV network is introduced in this paper.

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