通信系统中自适应回波抵消的一种新方法

语音分组传输系统的出现，对回波抵消技术提出了新的挑战。在回波抵消中一个关键的问题是需要快速有效地估计延迟时间。基于直接计算输入信号互相关函数的延迟估计方法，在实际应用中回波消除性能差，运算量大。为此提出了基于混合模型的延时估计方法，对输入信号进行带通滤波和降低抽样率抽样，使其具有白噪声特性，然后快速计算互相关函数的估计值。理论分析和实验结果证明新的延迟估计方法有很好的回波消除性能和较少的运算量，在实际通信系统中有较好的应用前景。

New method for adaptive echo cancellation in communication systems

The advent of packetized audio transmission system has resulted in challenging requirements for echo cancellation technology. One key aspect of this technology is the need to estimate, quickly and accurately, the delay in an echo path in the transmission media. Delay estimation based on direct application of cross-correlation has poor performance and high implementation cost for the echo cancellation. A new method was presented in this paper. Input signals are bandpass filtered, downsampled, and cross-correlation function is computed via using the whitened signals. Theoretical analysis and experiment results show that the new delay estimation has resulted in higher performance and lesser computation cost than the traditional delay estimation. This method has a broad application in communication systems.