基于DSP的FIR滤波器设计

摘要本文阐述了数字滤波器的特点和设计方法，对FIR和IIR滤波器进行了比较，对数字滤波器的应用范围、应用前景和发展历程作了详细的说明。介绍了利用MATLAB设计FIR滤波器的各种方法(包含窗函数设计法、频率样本设计法、等波动法和最小二乘法)以及如何用MATLAB中的滤波器设计工具fdatool设计各种类型的滤波器。选用TMS320LF2407A作为处理芯片进行硬件电路设计，根据最小系统的设计要点和注意事项设计了外围电路，包括时钟信号产生电路、DSP芯片供电电源电路、A/D数据采集、D/A数据恢复、前置放大电路及SPI串行通信接口电路、SPI接口寄存器配置等基本内容，结合外围电路原理完成系统原理图硬件电路设计。软件设计中通过MATLAB/SIMULINK环境中图形化的方式建立数字信号处理的模型进行DSP的设计和仿真验证，将设计的图形文件.mdl直接转换成C语言程序在CCS中运行。软件通过添加A/D,D/A接口程序，调试、编译后就可以下载到DSP目标板中。利用MATLAB软件开发产品加速了开发周期，比直接在CCs中编程方便快捷了很多，对于任何复杂功能的DSP系统，只需要进行少量的添加和修改就能完成功能正确的C语言程序设计。以一个FIR数字带阻滤波器的实现为例对TMS320LF2407A硬件接口电路及DSP程序进行调试，使之达到设计指标。设计的电路通过软件进行了验证并进行了环境实验，多次实验证明了电路工作稳定，满足设计要求。同时验证了FIR数字滤波器的线性相位，从该滤波器的相频响应曲线可以看出，滤波器输入和输出波形只有时间上的延迟，没有波形畸变。该FIR滤波器的相位响应可为严格的线性，因此它不存在延迟失真，只有固定的时间延迟，适用于图像信号处理、数据传输等以波形携带信息的系统。关键词:MATLAB,DSP,FIR，数字滤波器ABSTRACTThisarticletellsusthecharacteristicsanddesignmethodsofdigitalfilter,ItcomparedFIRwithIIRdigitalfilteranddetailedlynarratedtheapplicationarea、applicationforegroundanddevelopmentofdigitalfilter.ItparticularlyintroducesthedesignmethodofFIRdigitalfilterbasedonthesoftwareMATLABandhowtodesigndigitalfilterswithfdatoolwhichisthefilterdesigningtoolofMATLAB.ChoosetheTMS320LF2407Aastheprocessingchiptodesignthehardwarecircuit,onthebasisofthedesigningpoint,designtheperipheralcircuit,suchasclocksignalcircuit,powersupplycircuit,A/Dconversion,D/Aconversion,dataamplifyingcircuit,SPIcommunicationconnectioncircuitandSPIregistersconfiguration.Combiningtheperipheralcircuitfinishthesystemhardwarecircuit.Inthesoftwaredesigning,usingMATLAB/Simulinksetupthemodelofdatasignalprocessingandgoingalongtheimitating.ThefigurefilecanbemadeintotheClanguageprogramwhichisdownedintotheDSPaimingboard.ThisprogramneededappendingA/DandD/Ameetingprogram,debuggingandediting.ItcandesignandrealizemanyfunctionsusingthesemodelsandotherdigitalsignalprocessingmodelsundertheconditionofSimulink.TheprogramcanbemodifiedandeditedinthedevelopmentenvironmentCCS.MATLABacceleratedevelopingperiodandbemoreconvenientthanCCS.ThisarticlegivethehardwareinterfacecircuitdesigningandaClanguageprogramofdigitalbandstopfilter,choosingtheTMS320LF2407AandimitatingthemoduleofdigitalfilteringprocessingintheMATLAB/Simulink.Theprogramhasalreadybeenappliedinthehardwarecircuit.Manytestshasprovedthattheprogramworksstablyandmeetsthedesigningneeds.Atthesametime,thelinearphaseofFIRdigitalfilterisproved,thatis,theinputandoutputwavehasnodistortionbuttimedelay.KeyWords:MATLAB，DSP，FIR,Digitalfilterrr目录第1章绪论.........................................................................................................11.1课题研究的目的及意义..............................................................................11.2课题研究的现状........................................................................................31.3本课题研究的内容......................................................................................5第2章系统设计的理论基础….......................................................................62.1系统设计的理论依据.........................................................................62.1.1数字滤波器的概述..................……，..................................................62.1.2FIR和IIR滤波器的比较...................................................................82.1.3FIR滤波器的设计方法.....................................................................92.1.4FIR滤波器设计的一些深入问题.....................................................152.2开发工具及环境.......................................................................................172.2.1MATLAB中的滤波器设计工具.......................................................172.2.2DSP芯片开发工具..........................................................................192.3本章小结.............……，.............................……，........................................23第3章硬件设计..............................................................................................243.1滤波器设计指标.......................................................................................243.2DSP芯片的选择........................................................................................243.3硬件设计过程...........................................................................................273.3.1电源设计及外部时钟信号输入..，...................................................273.3.2A/D与DSP芯片的连接.................................................................273.3.3D/A与DSP芯片的连接..................................................................313.4本章小结.....……，，……‘.....，..................，......……‘....，.......................……，二34第4章软件设计.............................................................................................354.1用MATLAB建立滤波模型.........................……，....................................354.2程序设计……，，.....……，.，....……，..................……‘.......................................384.2.1初始化设置.....................................................................................384.2.2程序流程.................……，................................................................404.2.3程序清单....……，...................，..，.......................…，..........................464.3设计结果..........