Abstract: To improve the convergence rate of digital repeater echo cancellation, firstly, the echo cancellation technique based on adaptive filter was studyed; secondly, the recursion algorithm of adaptive filter was improved by the technical schemes that two adaptive filters compute in parallel and update the weights jointly and recursively. Since the error signal to adjust weights of the two adaptive filters was generated in different ways, the schemes were divided into two categories: scheme one is that the weights of two filters were adjusted by error signal of echo cancellation (simultaneously); scheme two is that the weights of the first filter were adjusted by error signal as the difference value of received signal from antenna and output signal of the first filter; and the weights of the second filter were adjusted by error signal as the difference value of the above-mentioned error signal and the output signal of the second filter (separately). The simulation results show that the convergence rate of the echo cancellation is increased by 11.11%~17.78% in the improved technique scheme, so as to improve the condition effectively with the slow convergence rate of digital repeater echo cancellation.

Key words: digital repeater, error signal, adaptive filter, echo cancellation, convergence rate

摘要： 为了提高数字直放站回波抵消的收敛速度，首先研究了基于自适应滤波器的回波抵消技术，然后对其中的自适应滤波器的递推算法进行改进，形成了两个自适应滤波器并行计算、联合递推更新权值的技术方案。由于调节两个自适应滤波器权值的误差信号产生方式不同，方案可分为两种：方案一将回波抵消后的信号同时作为调节两个滤波器权值的误差信号(同时)；方案二将天线接收信号与第一个滤波器输出信号的差值作为调节第一个滤波器权值的误差信号，而将该误差信号与第二个滤波器输出信号的差值作为调节第二个滤波器权值的误差信号(分别)。仿真结果表明，改进技术方案使回波抵消收敛速度提高11.11%~17.78%，从而有效改善了数字直放站回波抵消收敛速度慢的状况。

关键词: 数字直放站, 误差信号, 自适应滤波器, 回波抵消, 收敛速度