电子信息工程 基于LMS、NLMS算法设计 回声抵消器的设计与实现.docxVIP

毕业设计(论 文)回声抵消器的设计与实现系 别电子信息系专业名称电子信息工程班级学号5081217学生姓名李浩亮指导教师韩英华 2012年6月3日回声抵消器的设计与实现摘 要同时使用麦克风和扬声器的通信场合，例如会议电视、免提电话等系统终端，回声抵消器是一个必不可少的设备。它有两个主要功能，一是消除因本地扬声器和麦克风之间因声耦合而产生的声回声；二是保证系统的稳定性，以免在声反馈严重时引起啸叫。 回声抵消器的基本原理是用一个自适应滤波器来辨识并模拟回声路径以实现回声对消。由于通信系统及语音信号本身的不固定性，加上许多场合对自适应滤波器的特殊考虑，对所采用自适应算法的性能要求很高，例如快速收敛、顽健性强和运算简单等，而近年来数字信号处理器的快速发展，也使自适应滤波器实时、经济地实现成为可能。本文首先对回声消除技术原理做以系统介绍分析，其次在分析自适应滤波器原理的基础之上研究了标准LMS和归一化NLMS两种自适应滤波算法，并对这两种算法的性能进行了仿真比较，利用Simulink对所设计的回声抵消系统进行了仿真设计。在讨论回声抵消器原理和算法的基础上，给出了基于DSP的回声抵消器的设计方案。在设计中采用了标准LMS算法，利用 TI公司的 DSP TMS320系列芯片作为处理单元实现了回声抵消。关键词：自适应滤波，LMS算法，回声抵消，SimulinkThe Research and Implementation of Acoustic Echo Canceller Author：Li HaoliangTutor：Han YinghuaAbstractAcoustic Echo Canceller (AEC) is an indispensable device applied in many communication situations, such as hands-free wireless systems, Teleconferencing etc, where a loudspeaker and a microphone are placed within an enclosure. The AEC has two main functions: eliminating the echoes due to acoustic feedback from loudspeaker to microphone and protecting the communication systems from howling and becoming unstable when this kind of feedback becomes seriously. The fundamental of AEC is cancelling the echo by employing an adaptive filter to identify and simulate the real echo paths. What makes the capability of an adaptive algorithm applied in AEC very demanding is the highly non stationary nature of the involved signals and systems, as well as the very long filters required. The performance of an algorithm can be measured by some factors, such as the accuracy of the obtained solution with respect to the theoretically expected set up; the convergence speed; the robustness to round off error accumulation complexity etc.The echo cancellation technology principle to the system introduced and analyzed, followed by analysis of adaptive filter principle based on the standards the LMS, normalized NLMS, and the performance of these two algorithms, simulation comparison, the use of Simulink simulation and De