音頻頻譜分析儀設(shè)計(jì)與實(shí)現(xiàn)

1、實(shí)驗(yàn)八 音頻頻譜分析儀設(shè)計(jì)與實(shí)現(xiàn)1、 實(shí)驗(yàn)原理MATLAB是一個(gè)數(shù)據(jù)分析和處理功能十分強(qiáng)大的工程實(shí)用軟件，其數(shù)據(jù)采集工具箱為實(shí)現(xiàn)數(shù)據(jù)的輸入和輸出提供了十分方便的函數(shù)和指令。本實(shí)驗(yàn)基于聲卡與MATLAB實(shí)現(xiàn)音頻信號(hào)頻譜分析儀。 1、頻率(周期)檢測(cè) 對(duì)周期信號(hào)來說，可以用時(shí)域波形分析來確定信號(hào)的周期，也就是計(jì)算相鄰兩個(gè)信號(hào)波峰的時(shí)間差或過零點(diǎn)的時(shí)間差。采用過零點(diǎn)（ti）的時(shí)間差T（周期）。頻率即為f=1/T，由于能夠求得多個(gè)T值，故采用他們的平均值作為周期的估計(jì)值。 2、峰值檢測(cè) 在一個(gè)周期內(nèi)，求出信號(hào)最大值與最小值的差得一半記為A，同樣得到多個(gè)A值，但第一個(gè)A值對(duì)應(yīng)的和不是在一個(gè)周期內(nèi)搜索得到

2、的，故以除第一個(gè)以外的A值的平均作為幅值的估計(jì)值。 3、相位檢測(cè) 采用過零法，即通過判斷與同頻零相位信號(hào)過零點(diǎn)時(shí)刻，計(jì)算其時(shí)間差，然后換成相應(yīng)的相位差。，同樣以的平均值作為相位的估計(jì)值。 4、數(shù)字信號(hào)統(tǒng)計(jì)量估計(jì) （1）峰值P的估計(jì) 在樣本數(shù)據(jù)x中找出最大值與最小值，其差為雙峰值，雙峰值的一半即為峰值。 （2）均值估計(jì) ，N為樣本容量。 （3）均方值估計(jì) （4）方差估計(jì) 5、頻譜分析原理 時(shí)域分析只能反映信號(hào)的幅值隨時(shí)間的變化情況，除但頻率分量的簡(jiǎn)單波形外，很難明確提示信號(hào)的頻率組成和各頻率分量大小，而頻譜分析能很好的解決此問題。（1）DFT與FFT對(duì)于給定的時(shí)域信號(hào)y，可以通過Fourier變

3、換得到頻域信息Y。Y可按下式計(jì)算式中，N為樣本容量，t = 1/Fs為采樣間隔。采樣信號(hào)的頻譜是一個(gè)連續(xù)的頻譜，不可能計(jì)算出所有的點(diǎn)的值，故采用離散Fourier變換(DFT)，即式中，f = Fs/N。但上式的計(jì)算效率很低，因?yàn)橛写罅康闹笖?shù)(等價(jià)于三角函數(shù))運(yùn)算，故實(shí)際中多采用快速Fourier變換(FFT)。其原理即是將重復(fù)的三角函數(shù)算計(jì)的中間結(jié)果保存起來，以減少重復(fù)三角函數(shù)計(jì)算帶來的時(shí)間浪費(fèi)。由于三角函數(shù)計(jì)算的重復(fù)量相當(dāng)大，故FFT能極大地提高運(yùn)算效率。（2） 頻率、周期的估計(jì) 對(duì)于Y(kf)，如果當(dāng)kf = 時(shí)，Y(kf)取最大值，則為頻率的估計(jì)值，由于采樣間隔的誤差，也存在誤差，其誤

4、差最大為f / 2。周期T=1/f。從原理上可以看出，如果在標(biāo)準(zhǔn)信號(hào)中混有噪聲，用上述方法仍能夠精確地估計(jì)出原標(biāo)準(zhǔn)信號(hào)的頻率和周期。 （3）頻譜圖為了直觀地表示信號(hào)的頻率特性，工程上常常將Fourier變換的結(jié)果用圖形的方式表示，即頻譜圖。以頻率f為橫坐標(biāo)，|Y(f)|為縱坐標(biāo)，可以得到幅值譜；以頻率f為橫坐標(biāo)，arg Y(f)為縱坐標(biāo)，可以得到相位譜；以頻率f為橫坐標(biāo)，Re Y(f)為縱坐標(biāo)，可以得到實(shí)頻譜；以頻率f為橫坐標(biāo)，Im Y(f)為縱坐標(biāo)，可以得到虛頻譜。根據(jù)采樣定理，只有頻率不超過Fs/2的信號(hào)才能被正確采集，即Fourier變換的結(jié)果中頻率大于Fs/2的部分是不正確的部分，故不

5、在頻譜圖中顯示。即橫坐標(biāo)f 0, Fs/26、 模塊劃分 模塊化就是把程序劃分成獨(dú)立命名且可獨(dú)立訪問的模塊，每個(gè)模塊完成一個(gè)子功能，把這些模塊集成起來構(gòu)成一個(gè)整體，可以完成制定的功能，滿足用戶需求。2、 實(shí)驗(yàn)內(nèi)容設(shè)計(jì)一個(gè)音頻頻譜分析儀，功能包括：（1） 音頻信號(hào)輸入，從聲卡輸入、從WAV文件輸入、從標(biāo)準(zhǔn)信號(hào)發(fā)生器輸入；（2） 信號(hào)波形分析，包括幅值、頻率、周期、相位的估計(jì)，以及統(tǒng)計(jì)量峰值、均值。均方值和方差的計(jì)算。（3） 信號(hào)頻譜分析，頻率、周期的估計(jì)，圖形顯示幅值譜、相位譜、時(shí)頻譜、虛頻譜和功率譜的曲線。3 實(shí)驗(yàn)結(jié)果1.聲卡輸入（1） 正弦波 （2）方波（3） 三角波（4） 鋸齒波（5） 白

6、噪聲程序function varargout = fanwenhan(varargin)gui_Singleton = 1;gui_State = struct('gui_Name', mfilename, . 'gui_Singleton', gui_Singleton, . 'gui_OpeningFcn', fanwenhan_OpeningFcn, . 'gui_OutputFcn', fanwenhan_OutputFcn, . 'gui_LayoutFcn', , . 'gui_Callback

7、', );if nargin && ischar(varargin1) gui_State.gui_Callback = str2func(varargin1);end if nargout varargout1:nargout = gui_mainfcn(gui_State, varargin:);else gui_mainfcn(gui_State, varargin:);endfunction fanwenhan_OpeningFcn(hObject, eventdata, handles, varargin)handles.inputtype=0;xlabel(

8、handles.plot1,'freqency(Hz)');xlabel(handles.plot2,'freqency(Hz)');xlabel(handles.plot3,'freqency(Hz)');xlabel(handles.plot4,'freqency(Hz)');xlabel(handles.plot5,'freqency(Hz)');ylabel(handles.plot1,'amplitude');ylabel(handles.plot2,'phase(rad)'

9、;);ylabel(handles.plot3,'real');ylabel(handles.plot4,'Imaginary');ylabel(handles.plot5,'power');handles.output = hObject;function varargout = fanwenhan_OutputFcn(hObject, eventdata, handles) varargout1 = handles.output;function figure1_CreateFcn(hObject, eventdata, handles)fu

10、nction timeanalyse_Callback(hObject, eventdata, handles)Fs=str2double(get(findobj('Tag','samplerate'),'String');N=str2double(get(findobj('Tag','samplenum'),'String');if handles.inputtype=0 msgbox('No wave exist! Please choose a input type!'); r

11、eturn;endn=1;ymax=max(handles.y(1) handles.y(2);ymin=min(handles.y(1) handles.y(2);from=str2double(get(handles.pointfrom,'String');to=str2double(get(handles.pointto,'String');if from<1 | to-from<5; msgbox('Error range!'); return;endfor i=from+2:to-1; if handles.y(i-1)&l

12、t;0 & handles.y(i-2)<0 & handles.y(i)>=0 & handles.y(i+1)>0 if handles.y(i)=0 ti(n)=i; else ti(n)=i-handles.y(i)/(handles.y(i)-handles.y(i-1); end amp(n)=(ymax-ymin)/2; ymax=0; ymin=0; n=n+1; else if ymax<handles.y(i) ymax=handles.y(i); end if ymin>handles.y(i) ymin=handle

13、s.y(i); end endendn=n-1;for i=1:n-1 T(i)=ti(i+1)-ti(i);endfreq=Fs/mean(T);set(handles.outt,'String',1/freq);set(handles.outfreq,'String',num2str(freq);set(handles.outamp,'String',num2str(mean(amp(2:n-1);phase=2*pi*(1-(ti(1:n-1)-1)./T+floor(ti(1:n-1)-1)./T);set(handles.outphas

14、e,'String',num2str(mean(phase);set(handles.outpeak,'String',(max(handles.y(from:to)-min(handles.y(from:to)/2);set(handles.outmean,'String',mean(handles.y(from:to);set(handles.outmeansquare,'String',mean(handles.y(from:to).2);set(handles.outs,'String',std(handl

15、es.y(from:to)2);function WAVfile_Callback(hObject, eventdata, handles)h=findobj('Tag','filename');set(h,'enable','on');h=findobj('Tag','freq');set(h,'enable','off');h=findobj('Tag','amp');set(h,'enable','off&

16、#39;);h=findobj('Tag','phase');set(h,'enable','off');set(findobj('Tag','recordtime'),'enable','off');set(handles.channel,'enable','on');set(handles.fileopen,'enable','on');set(handles.gensig,'enable&#

17、39;,'off');set(handles.wavetype,'enable','off');set(handles.add,'enable','off');set(handles.startrecord,'enable','off');function soundcard_Callback(hObject, eventdata, handles)set(findobj('Tag','recordtime'),'enable',

18、9;on');h=findobj('Tag','filename');set(h,'enable','off');h=findobj('Tag','freq');set(h,'enable','off');h=findobj('Tag','amp');set(h,'enable','off');h=findobj('Tag','phase');set(h,'

19、enable','off');set(handles.channel,'enable','off');set(handles.fileopen,'enable','off');set(handles.gensig,'enable','off');set(handles.wavetype,'enable','off');set(handles.add,'enable','off');set(handles.star

20、trecord,'enable','on');function generator_Callback(hObject, eventdata, handles)h=findobj('Tag','filename');set(h,'enable','off');h=findobj('Tag','freq');set(h,'enable','on');h=findobj('Tag','amp');set(h,&

21、#39;enable','on');h=findobj('Tag','phase');set(h,'enable','on');set(findobj('Tag','recordtime'),'enable','off');set(handles.channel,'enable','off');set(handles.fileopen,'enable','off');set(han

22、dles.gensig,'enable','on');set(handles.wavetype,'enable','on');set(handles.add,'enable','on');set(handles.startrecord,'enable','off'); function filename_Callback(hObject, eventdata, handles)function filename_CreateFcn(hObject, eventdata

23、, handles)if ispc set(hObject,'BackgroundColor','white');else set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor');end function freq_Callback(hObject, eventdata, handles)function freq_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'Bac

24、kgroundColor','white');else set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor');end function amp_Callback(hObject, eventdata, handles)function amp_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white');else

25、set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor');end function phase_Callback(hObject, eventdata, handles)function phase_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white');else set(hObject,'BackgroundColor'

26、;,get(0,'defaultUicontrolBackgroundColor');end function samplerate_Callback(hObject, eventdata, handles)function samplerate_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white');else set(hObject,'BackgroundColor',get(0,'defaultUicont

27、rolBackgroundColor');end function samplenum_Callback(hObject, eventdata, handles)function samplenum_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white');else set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor');end

28、 function ampfreq_CreateFcn(hObject, eventdata, handles)function recordtime_Callback(hObject, eventdata, handles)function recordtime_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white');else set(hObject,'BackgroundColor',get(0,'defaultUicon

29、trolBackgroundColor');end function startrecord_Callback(hObject, eventdata, handles)Fs=str2double(get(findobj('Tag','samplerate'),'String');handles.y=wavrecord(str2double(get(findobj('Tag','recordtime'),'String')*Fs, Fs,'int16');handles.inp

30、uttype=1;guidata(hObject,handles);plot(handles.time,handles.y);title('WAVE');ysize=size(handles.y)set(handles.samplenum,'String',num2str(ysize(1); function fileopen_Callback(hObject, eventdata, handles) temp = wavread(get(findobj('Tag','filename'),'String');ch

31、annel=str2double(get(handles.channel,'String');handles.y=temp(:,channel);handles.inputtype=2;guidata(hObject,handles);plot(handles.time,handles.y);title('WAVE');ysize=size(handles.y)set(handles.samplenum,'String',num2str(ysize(1);function gensig_Callback(hObject, eventdata, h

32、andles)Fs=str2double(get(findobj('Tag','samplerate'),'String');N=str2double(get(findobj('Tag','samplenum'),'String');x=linspace(0,N/Fs,N);soundtype=get(handles.wavetype,'Value');frequency=str2double(get(handles.freq,'String');amp=str2do

33、uble(get(handles.amp,'String');phase=str2double(get(handles.phase,'String');switch soundtype case 1 y=amp*sin(2*pi*x*frequency+phase); case 2 y=amp*sign(sin(2*pi*x*frequency+phase); case 3 y=amp*sawtooth(2*pi*x*frequency+phase,0.5); case 4 y=amp*sawtooth(2*pi*x*frequency+phase); case

34、 5 y=amp*(2*rand(size(x)-1); otherwise errordlg('Illegal wave type','Choose errer');endif get(handles.add,'Value')=0.0 handles.y=y;else handles.y=handles.y+y;endhandles.inputtype=3;guidata(hObject,handles);plot(handles.time,handles.y);title('WAVE');axis(0 N -str2doubl

35、e(get(handles.amp,'String') str2double(get(handles.amp,'String'); function outfreq_Callback(hObject, eventdata, handles)function outfreq_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white');else set(hObject,'BackgroundColor',get

36、(0,'defaultUicontrolBackgroundColor');end function outamp_Callback(hObject, eventdata, handles)function outamp_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white');else set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackground

37、Color');end function outphase_Callback(hObject, eventdata, handles)function outphase_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white');else set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor');end function outpe

38、ak_Callback(hObject, eventdata, handles)function outpeak_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white');else set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor');end function outmean_Callback(hObject, eventdata,

39、handles)function outmean_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white');else set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor');end function outmeansquare_Callback(hObject, eventdata, handles)function outmeansq

40、uare_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white');else set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor');end function outs_Callback(hObject, eventdata, handles)function outs_CreateFcn(hObject, eventdata, han

41、dles)if ispc set(hObject,'BackgroundColor','white');else set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor');end function foutfreq_Callback(hObject, eventdata, handles)function foutfreq_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'

42、BackgroundColor','white');else set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor');end function foutamp_Callback(hObject, eventdata, handles)function foutamp_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white&

43、#39;);else set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor');end function foutphase_Callback(hObject, eventdata, handles)function foutphase_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white');else set(hObject,'

44、BackgroundColor',get(0,'defaultUicontrolBackgroundColor');end function edit18_Callback(hObject, eventdata, handles)function edit18_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white');else set(hObject,'BackgroundColor',get(0,'de

45、faultUicontrolBackgroundColor');end function edit19_Callback(hObject, eventdata, handles)function edit19_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white');else set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor'

46、);end function edit20_Callback(hObject, eventdata, handles)function edit20_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white');else set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor');end function edit21_Callback(hOb

47、ject, eventdata, handles)function edit21_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white');else set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor');end function freqanalyse_Callback(hObject, eventdata, handles)Fs=s

48、tr2double(get(findobj('Tag','samplerate'),'String');N=str2double(get(findobj('Tag','samplenum'),'String');if handles.inputtype=0 msgbox('No wave exist! Please choose a input type!'); return;endfrom=str2double(get(handles.pointfrom,'String&#

49、39;);to=str2double(get(handles.pointto,'String');sample=handles.y(from:to);f=linspace(0,Fs/2,(to-from+1)/2);Y=fft(sample,to-from+1);C,I=max(abs(Y);set(handles.foutt,'String',1/f(I);set(handles.foutfreq,'String',f(I);Y=Y(1:(to-from+1)/2);plot(handles.plot1,f,2*sqrt(Y.*conj(Y);

50、plot(handles.plot2,f,angle(Y);plot(handles.plot3,f,real(Y);plot(handles.plot4,f,imag(Y);plot(handles.plot5,f,abs(Y).2);xlabel(handles.plot1,'freqency(Hz)');xlabel(handles.plot2,'freqency(Hz)');xlabel(handles.plot3,'freqency(Hz)');xlabel(handles.plot4,'freqency(Hz)');x

51、label(handles.plot5,'freqency(Hz)');ylabel(handles.plot1,'amplitude');ylabel(handles.plot2,'phase(rad)');ylabel(handles.plot3,'real');ylabel(handles.plot4,'Imaginary');ylabel(handles.plot5,'power'); function pointfrom_Callback(hObject, eventdata, handl

52、es)function pointfrom_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white');else set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor');end function pointto_Callback(hObject, eventdata, handles)function pointto_CreateFcn(

53、hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white');else set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor');end function play_Callback(hObject, eventdata, handles)Fs=str2double(get(findobj('Tag','samplerate'),

54、'String');wavplay(handles.y,Fs); function scale_Callback(hObject, eventdata, handles)val=get(hObject,'value');val=10(val*5+1);x=get(handles.xmove,'Value')*str2double(get(handles.samplenum,'String');axis(handles.time,x val+x min(handles.y) max(handles.y); function scal

55、e_CreateFcn(hObject, eventdata, handles)usewhitebg = 1;if usewhitebg set(hObject,'BackgroundColor',.9 .9 .9);else set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor');end function scale2_Callback(hObject, eventdata, handles)val=get(hObject,'value');v

56、al=10(val*5+1);xlim(handles.plot1,0 val);xlim(handles.plot2,0 val);xlim(handles.plot3,0 val);xlim(handles.plot4,0 val);function scale2_CreateFcn(hObject, eventdata, handles)usewhitebg = 1;if usewhitebg set(hObject,'BackgroundColor',.9 .9 .9);else set(hObject,'BackgroundColor',get(0,&

57、#39;defaultUicontrolBackgroundColor');end function channel_Callback(hObject, eventdata, handles)function channel_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white');else set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor');end function wavetype_Callback(hObject, eventdata, handles)function wavetype_CreateFcn(hObject, eventdata, handles)if ispc set(hObject,'BackgroundColor','white');else set