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1、 本科毕业设计本科毕业设计(论文论文)题目:自适应滤波器的计算机实现题目:自适应滤波器的计算机实现院院 (系):(系): 专专 业:业: 班班 级:级: 学学 生:生: 学学 号:号: 指导教师:指导教师: 2012 年年 6 月月自适应滤波器的计算机实现自适应滤波器的计算机实现摘要摘要自适应滤波器是当今自适应信号处理中最为活跃的研究课题之一。自适应 滤波器有广阔的应用前景,特别是在数字通信领域,自适应均衡是一种成熟技 术,对包括语音频带、微波、对流层散射无线通信、有线电视调制解调器等数 字通信系统影响最大。在无线通信系统中,一般很难知道接收信号的自相关量 和接收信号与发送信号的相关量,对于维
2、纳滤波器,需要事先估计出自相关与互 相关量,这是非常不方便的。虽然卡尔曼滤波方法无需事先知道自相关与互相 关量,但它必须知道系统的状态方程和噪声的统计特性,这在实际中也是很难 办到的。根据卡尔曼滤波的思想,Widrow 等提出了一种自适应最小均方误差算 法(LMS),这种算法不需要事先知道相关矩阵,只需调整 FIR 滤波器的权系数, 便可使接收信号收敛于最佳值,因此对自适应滤波器的研究非常有意义。本论 文在 MATLAB 平台上编写自适应算法的 M 文件,进行系统仿真,并对滤波器的阶 数、收敛步长、跟踪速度和稳态误差进行了详细的分析和研究,得出了合理的 结果。关键词关键词:自适应均衡,自适应滤
3、波器,LMS 算法 ,MATLAB 仿真Computer realization of the adaptive filterAbstractThe research of adaptive filter is one of the most activity tasks. The adaptive filter has been widely used in various technique fields, particularly in digital communication, adaptive equalization is a kind of mature technology,
4、 it have great impact on digital communication system such as Audio frequency, microwave, wireless communication via tropospheric scatter, modem of cable TV and so on. In general ,it is difficult to know the received signals autocorrelation volume and correlation volume of the received signal and th
5、e sent signal In wireless communication systems . The Wiener filter needs to estimate autocorrelation and cross correlation volume which is very inconvenient. Although the Kalman filtering method does not need to know the autocorrelation and cross correlation volume in advance, it must know the stat
6、e equation of system and the statistical characteristics of noise, which is very difficult in practice. Widrow proposed a least mean square error of adaptive algorithm (LMS) Based on the idea of the Kalman, this algorithm does not need to know the correlation matrix in advance, simply adjust the wei
7、ght coefficients of the FIR filter, then you can receive the signal that converge the best value, so the research of the adaptive filter is very meaningful. In this paper the M-file of the adaptive algorithm have be written in MATLAB platform so that Completed system simulation, detailed analysis an
8、d research for filter order, convergence step, the tracking speed and steady state error were Completed , and reasonable results were obtained.Keywords: adaptive equalization,adaptive filter,LMS algorithm,MATLAB simulation目录目录摘要摘要.IABSTRACT.II略略 语语 表表.I1绪论绪论.11.1 前言.11.2 课题研究的意义.11.3 通信系统中的失真分析.11.3
9、.1 数字基带传输系统模型.11.3.2 通信系统中的噪声干扰.31.3.3 通信系统的传输特性.51.4 自适应滤波技术.61.4.1 自适应滤波理论.61.4.2 均衡技术.61.5 主要研究内容.71.5.1 论文的研究目标.71.5.2 论文的研究意义.71.5.3 论文的章节安排.82 2自适应滤波原理与应用自适应滤波原理与应用.92.1 自适应滤波原理.92.1.1 自适应滤波器的分类.92.1.2 自适应滤波器的基本构成.102.1.3 与普通滤波器的区别.102.1.4 自适应过程.112.2 自适应滤波结构.112.2.1 单位脉冲响应类型.112.2.2 滤波器的实现结构.122.2.3 横向型 FIR 自适应滤波器.