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分析了 IP电话系统中回声的特点 ,并针对其回声具有路径延迟、延迟抖动大等特点 ,提出了一种基于延迟分析的自适应回声消除器设计的新思想和相关算法。介绍了自适应回声消除器的基本结构及各个功能模块 ,例如 :变阶数自适应滤波器 ,语音状态检测器 ,延迟分析器和 NL MS算法控制器 .本文还详细论述了以 TMS32 0 C62 0 1DSP为硬件平台来实现能运用在 IP电话网关中的自适应回声消除器及其在 IP电话系统中的连接关系。在文章的最后 ,列举了对自适应回声消除器的性能测试结果 ,并分析了自适应回声消除器的优点 ,证明了自适应回声消除器能很好地解决 IP电话系统中的回声消除问题。
In this paper, the characteristics of echo in IP telephone system are analyzed. A new idea and algorithm of adaptive echo canceller based on delay analysis is proposed for the characteristics of path echo and delay jitter. The basic structure of adaptive echo canceller and its various functional modules are introduced, such as variable-order adaptive filter, speech state detector, delay analyzer and NL MS algorithm controller.In addition, the paper discusses the TMS32 0 C62 0 1DSP is a hardware platform to implement an adaptive echo canceller that can be used in an IP telephony gateway and its connection in an IP telephony system. At the end of the article, the performance test results of the adaptive echo canceller are listed, and the advantages of the adaptive echo canceller are analyzed. It is proved that the adaptive echo canceller can solve the echo cancellation problem in the IP telephone system.