matlab滤波器与均衡器设计方案

1、封面仅供个人学习作者：PanHongliangDigital sig nal andanalysisTitle:A filter and equilizerName:Yan gxiaoClass:Master of mecha ni cal engin eeri ng 1302Student ID:M201370503Abstrac:tDesigning some kinds of filters by using matlab.We canunderstand the signal processing of filter more comprehensive by analyzingthe

2、 filtering properties of different filters.Designing anadjustable parameterof digital filter which is called equalizer.In this paper, the digital equalizerwhich is based on MATLAB platform designing has the functionsofaccessing Wav file , filtering and playing.Keyword:Matlab,Filter,Equalizer1. Prefa

3、ceMATLAB is called Matrix Laborator，y which is designed by the UnitedStates MathWorks company.Its a commercial mathematical software.Matlab can be use for Matrix operations, mapping functions and data,algorithm, creating the user interface, connect to other programminglanguages procedures, mainly us

4、ed in engineering calculations, controldesign, signal processing and communications, image processing, signaldetection, design and financial modeling analysis and other fields. GUI(Graphical User Interface, referred to as GUI, known Graphical UserInterface) is displayed using the graphical user inte

5、rface of computeroperations. Matlab has a powerful GUl tool. In this report, by using matlabGUI tool we could design a signal filter and equalizer.The filter Can be divided into low-pass, high-pass filter, band pass andband-stop filter.Low-pass filter: it allows signal in low frequency or dc compone

6、nt through, suppress the high freque ncy comp onent or the interferenceand noise.High-pass filter: it allows the signal in high freque ncy , restrainlow freque ncy or dc comp onen t.Ba nd-pass filter: it allows a spectrum ofsig nal through and restra in the sig nal below or above the spectrum,interf

7、erence and noise.Band-stop filter: it inhibit the signal within a certainfrequency band and pass the signal outside the spectrum.2. IntroduceThe filter which is designed by using matlab have four functions :low-pass,high-pass,ba nd-stop and ban d-pass .Every fun cti on could in put thecut-off freque

8、 ncies.The equalizer could filter the wav file in putted as we wan t.The in terface is that:2.1 In terface3. Design PrinciplesThe task is to design the filter and equalizer which can edit thein putt ing sig nal as we want and choose the freque ncy spectrum to pass.3.1 the standard signal inputWe des

9、ig n a sig nal gen erator which is used to gen erator sta ndardwaveform such as sin ,square,tria ngular,sawtooth and no ise.A nd we candecide whether addi ng differe nt waves .The program is:Fs=10000N=400。x=linspace(0,N/Fs,N)。t=get(handles.WaveMake,Value。)f=str2double(get(handles.frequency,String)。)

10、a=str2double(get(handles.amplitude,String)。) p=0。switch tcase 1y=a*sin(2*pi*x*f+p) 。if get(handles.add,Value)=0.0 handles.y=y。elsehandles.y=handles.y+y。endcase 2 case 5y=a*(2*rand(size(x)-1) 。if get(handles.add,Value)=0.0 handles.y=y。elsehandles.y=handles.y+y。endendhandles.inputtype=3。guidata(hObjec

11、t,handles)。 plot(handles.axes1,handles.y。)xlim(0 200) 。temple=handles.y。f=linspace(0,Fs/2,N/2)。P=2*fft(temple,N)/N 。Pyy=sqrt(P.* conj(P)。plot(handles.axes2,f,Pyy(1:N/2)。The interface is:3.1 the image of waveform3.2 the wave filteringBy choosing the working mode of filter and input cut-off frequencie

12、s wecan realize the filtering.Theprogram is:y=handles.y。FC=str2double(get(handles.hf,string)。Fs=22000。n=44100。N=8 。Wn=FC/(Fs/2)。% the low-pass programb,a = butter(N,Wn,low) 。 z=filter(b,a,y) 。P=fft(z,n) 。 f=linspace(0,Fs/2,n/2)。Pyy=2*sqrt(P.* conj(P)/n 。 plot(handles.axes3,z。)plot(handles.axes4,f,Py

13、y(1:n/2)。 handles.z=z。guidata(hObject,handles)。By running the program we can realize low-pass filter3.2 the image of low-pass filterThe high-pass program is: b,a = butter(N,Wn,high) 。 z=filter(b,a,y) 。P=fft(z,n) 。 f=linspace(0,Fs/2,n/2)。Pyy =2*sqrt(P.* conj(P)/n 。 plot(handles.axes3,z。)plot(handles.

14、axes4,f,Pyy(1:n/2)。 handles.z=z。guidata(hObject,handles)。By running the program we can realize high-pass filter3.3 the image of high-pass filterThe band-stop program is:b,a = butter(N,Wn,stop)。z=filter(b,a,y) 。P=fft(z,n) 。f=linspace(0,Fs/2,n/2)。Pyy=2*sqrt(P.* conj(P)/n 。plot(handles.axes3,z。 ) plot(

15、handles.axes4,f,Pyy(1:n/2)。handles.z=z。guidata(hObject,handles。)By running the program we can realize band-stop filter3.4 the image of band-stop filterThe band-pass program is: b,a = butter(N,Wn,bandpass)。z=filter(b,a,y) 。P=fft(z,n) 。f=linspace(0,Fs/2,n/2)。handles.Pyy=2*sqrt(P.* conj(P)/n 。plot(hand

16、les.axes3,z。)plot(handles.axes4,f,handles.Pyy(1:n/2)。)handles.z=z。guidata(hObject,handles。)By running the program we can realize band-pass filter3.5 the image of band-pass filter3.3 the equalizer filteringWe can open a wav file by run this program:filename,pathname=uigetfile(*.wav,select a wavfile)

17、。if isequal(filename,0)disp(the user cancels to select。)elsestr=strcat(pathname,filename。) disp(strcat(the user select ,str)。)set(handles.filename,string,str。)endy,Fs,bits=wavread(str)。handles.y=y。handles.z=y。guidata(hObject,handles)。When we choose a wav file, we can realize equalizer filter by sett

18、ingthe values of The scroll bars and run the program:handles.a=handles.y(:,1。) y=handles.a。 l=length(y) 。Fs=44100。%t=(0:l-1)/Fs 。Y=zeros(size(y)。A1=get(handles.slider1,value)。b,a=butter(2,30/(Fs/2),60/(Fs/2),bandpass)。Y=Y+2*A1*filter(b,a,y) 。A2=get(handles.slider2,value)。b,a=butter(2,60/(Fs/2),100/(

19、Fs/2),bandpass)。Y=Y+2*A2*filter(b,a,y) 。A3=get(handles.slider3,value)。b,a=butter(2,100/(Fs/2),200/(Fs/2),bandpass。)Y=Y+2*A3*filter(b,a,y) 。A4=get(handles.slider4,value)。b,a=butter(2,200/(Fs/2),500/(Fs/2),bandpass。)Y=Y+2*A4*filter(b,a,y) 。A5=get(handles.slider5,value)。b,a=butter(2,500/(Fs/2),1000/(Fs

20、/2),bandpass。)Y=Y+2*A5*filter(b,a,y) 。A6=get(handles.slider6,value)。b,a=butter(2,1000/(Fs/2),2000/(Fs/2),bandpass。)Y=Y+2*A6*filter(b,a,y) 。A7=get(handles.slider7,value)。b,a=butter(2,2000/(Fs/2),4000/(Fs/2),bandpass。)Y=Y+2*A7*filter(b,a,y) 。A8=get(handles.slider8,value)。b,a=butter(2,4000/(Fs/2),8000/

21、(Fs/2),bandpass。)Y=Y+2*A8*filter(b,a,y) 。z=Y。Fs=44100。ysize=size(handles.y)。 N=str2double(num2str(ysize(1)。wavplay(z,Fs)。P=fft(y,N) 。Pyy1=2*sqrt(P.*conj(P)/N 。P=fft(z,N) 。Pyy =2*sqrt(P.* conj(P)/N 。 f=linspace(0,Fs/2,N/2)。%Original wave time=(1:length(y)/Fs 。 plot(handles.axes1,time,y)。%Original fre

22、quencyplot(handles.axes2,f,Pyy1(1:N/2)。%The equilizer wave plot(handles.axes3,time,z)。%The equilizer frequency plot(handles.axes4,f,Pyy(1:N/2)。guidata(hObject,handles)。The interface is:3.6 the image of equalizerWe can see the equalizer realize the function of frequency filtering well.4 .Exist proble

23、mThe interfaces are not enough beautifulThe equlizer cannt realize Pause, fast forward, and so on.The spectrum of music cannot be updated in real time.5. ConclusionWith the complement of the third project, the whole projects in thecourse have been finished.From the beginning when I dont know thecont

24、ent as well as the soft matlab very much ,in the end when I havecomplete all the projects with the matlab,it is really not easy.There is no need to say that I can make a simple system with the softmatlab now. The last one ,the filter and equalizer is the combination of thekno wledge that is obta ine

25、d from the desig ning the first two projects.With the basis of kno wledge in the course as well as matlab, I will not beafraid of the problem. Nothing is impossible to a willing mind. If we make upour mi nds to do a thi ng ,we will solve all the problems in the last.References1薛山.MATLAB 基础教程.M北京：清华大

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