目 录
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.自适应滤波器的研究工作主要包括自适应算法和硬件实现.
通过对自适应滤波原理,滤波结构,最佳滤波准则,自适应算法分析,比较和总结,选出了适合于FPGA硬件实现的滤波结构和自适应算法,即基于LMS自适应算法的FIR横向滤波器.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,为自适应滤波器的硬件实现打下了良好的理论基础.
在Quartus II平台上,用VHDL语言描述了自适应滤波器的结构,解决了正负数运算,定点数运算,乘累加运算等细节问题.在ALTERA公司的Stratix II系列的EP2S30F484C3(Advanced)芯片上,实现了基于LMS自适应算法的FIR横向滤波器的硬件设计与逻辑综合,并进行了模拟仿真,得出了正确的结果.
关键词:自适应均衡,LMS算法,MATLAB仿真,VHDL
Abstract
The 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, 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. The research activities about adaptive filter involve two aspects: adaptive algorithm and hardware realization.
The suitable filter architecture and adaptive algorithm for FPGA hardware realization are determined-LMS algorithm horizontal structural FIR filter, based on the analyses, comparisons and summarization of adaptive filter principle, the architecture of filter, optimum filter principle and the adaptive algorithms. On the MATLAB platform, the M file is written and system simulation experiment is put on. The main parameters such as number of filter exponent, step-size, track-speed, errors and so on are discussed, that provided a solid foundation for the hardware realization of adaptive filters
On the Quartus II platform, the adaptive filter is described and designed by VHDL. The difficulties of plus and minus number operation, fixed point number operation, multiply and add operation are solved. Ultimately the hardware design and logical synthesis of the LMS algorithm horizontal structural FIR filter is realized using EP2S30F484C3(Advanced) device of Stratix II family of ALTERA Company, the simulation is done and also the results is correct.

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