9600比特/秒二线制全双工数据传输系统中的回波抵消器

An Echo Canceller for 9600 Bit s Two-Wire Full Duplex Data Transmission

本文探讨高速数据传输系统中的回波抵消问题。在建立回波抵消器模型的基础上,按最小均方误差准则,导出了自适应滤波器抽头的统计梯度算法和抽头调节的收敛公式。理论分析和计算机模拟结果表明:运用码变换的方法来产生回波抵消信号是可行的,这将有利于用数字方法来实现。回波抵消器的工作与接收机完全独立,抽头的收敛特性只与调节步长和抽头数有关,而与回波信道的特性、远端发送的信号及输入信噪比无关。

The problems of echo cancellation in the system of high rate data transmission are studied in this paper.Based on building up a model of echo canceller, the convergence of gradient-type stochastic adjustment algorithm of an adaptive filter under the mean-squared error criterion is discussed.The theoretical analysis and the results of computer simulation showed that it is possible to build a cancelling signal by means of code transformation.This makes it convienent to realize the echo canceller in digital type.The operation of echo canceller is fully independent of the receiver. The convergence properties of the canceller depends only on the step size of adjustment and the number of taps of transversal filter,it is not influenced by the channel characteristics,the signals from far-end and the noise.