关键词: 回声消除系统, 滤波器阶数, 权值活跃部分

Abstract: Echo cancellation system use self-adapting filter to simulate the echo channel, the order of the adaptive filter have great impacts on the echo cancellation result, also the proper order can improve it. According to the weights of active region, it can simulate the basic echo channel. Firstly, the modified NLMS algorithm can frame the order of initial weight value and calculate the mean value and joggling states; then, it can adjust the active region by comparing threshold result and abandon inactive region; eventually, it can adjust the order of filter by the total number of frames. the modified NLMS algorithm not only retain the advantage of NLMS algorithm including simple structure and fast convergence, but also adjust the filter order at real time, it enhances the echo cancellation result effectively. The echo cancellation simulation results show that the filter misalignment coefficient of the improved NLMS algorithm is lower than the NLMS and PNLMS algorithm.

Key words: echo cancellation system, filter order, weights of active parts