sigdemo1.m

matlabDigitalSigalProcess内有文件若干

    % u = get(gcf,'userdata');
    freq=SIGDEMO1_DAT(1);
    amp=SIGDEMO1_DAT(2);
    N=SIGDEMO1_DAT(3);
    M=SIGDEMO1_DAT(4);
    min_dB=SIGDEMO1_DAT(5);
    fixed_x=SIGDEMO1_DAT(6);
    fixed_y=SIGDEMO1_DAT(7);
    time_line=SIGDEMO1_DAT(8);
    freq_line=SIGDEMO1_DAT(9);
    freq_field=SIGDEMO1_DAT(10);
    popup=SIGDEMO1_DAT(11);
    t=SIGDEMO1_DAT(14:14+N-1);
    window=SIGDEMO1_DAT(14+N:14+N+N-1);

    pt=get(gca,'currentpoint');
    x=pt(1,1);
    y=pt(1,2);

    amp1=y/fixed_y*amp;
    if (abs(amp1)>1.0),
       amp1=1.0*sign(amp1);
    end;
    if (abs(amp1)<0.05),
       amp1=0.05*sign(amp1);
    end;
    if (amp1 == 0),
        amp1=0.05;
    end;
    freq1=fixed_x/x*freq;

    val = get(popup,'Value');
    if (val == 1),
        f=amp1*sin(freq1*t*2*pi);
    elseif (val == 2),   % square wave
        tt=freq1*t*2*pi;
        tmp=rem(tt,2*pi);
        f=amp1*(2*rem((tt<0)+(tmp>pi | tmp<-pi)+1,2)-1);
    elseif (val == 3),   % sawtooth
        tt=freq1*t*2*pi;
        f=amp1*((tt < 0) + rem(tt,2*pi)/2/pi - .5)*2;
    end;
    set(time_line,'YData',f);
    F=fft(window.*f,2*M);
    F=F(1:M);
    w=(0:M-1)*pi/M;
    FF=20*log10(abs(F));
    ind=find(FF<min_dB);
    FF(ind)=NaN*ones(size(ind)); % put NaN's in where
             % min_dB shows up - this is to work around no clipping in xor mode
    set(freq_line,'YData',FF);
    set(freq_field,'String',num2str(freq1));

elseif strcmp(action,'up'),
    pt=get(gca,'currentpoint');
    x=pt(1,1);
    y=pt(1,2);

    set(gcf,'WindowButtonMotionFcn','');
    set(gcf,'WindowButtonUpFcn','');

    % u=get(gcf,'userdata');
    freq=SIGDEMO1_DAT(1);
    amp=SIGDEMO1_DAT(2);
    fixed_x=SIGDEMO1_DAT(6);
    fixed_y=SIGDEMO1_DAT(7);

    amp1=y/fixed_y*amp;
    if (abs(amp1)>1.0),
       amp1=1.0*sign(amp1);
    end;
    if (abs(amp1)<0.05),
       amp1=0.05*sign(amp1);
    end;
    freq1=fixed_x/x*freq;

    set(SIGDEMO1_DAT(8),'linestyle','-');
    SIGDEMO1_DAT(1)=freq1;  % set amplitude and frequency
    SIGDEMO1_DAT(2)=amp1;
    % set(gcf,'userdata',u);
    sigdemo1('redraw');

elseif strcmp(action,'done'),
    % close the figure window that is showing the window fnction:
    % u = get(gcf,'userdata');
    if (SIGDEMO1_DAT(12)~=-1),
        close(SIGDEMO1_DAT(12));
    end;
    close(gcf);
    clear global SIGDEMO1_DAT
    clear global ADDIT_DAT

elseif strcmp(action,'redraw'),
    % recomputes time and frequency waveforms and updates display
    % u = get(gcf,'userdata');
    freq=SIGDEMO1_DAT(1);
    amp=SIGDEMO1_DAT(2);
    N=SIGDEMO1_DAT(3);
    M=SIGDEMO1_DAT(4);
    min_dB=SIGDEMO1_DAT(5);
    time_line=SIGDEMO1_DAT(8);
    freq_line=SIGDEMO1_DAT(9);
    freq_field=SIGDEMO1_DAT(10);
    popup=SIGDEMO1_DAT(11);
    t=SIGDEMO1_DAT(14:14+N-1);
    window=SIGDEMO1_DAT(14+N:14+N+N-1);
    val = get(popup,'Value');
    if (val == 1),
        f=amp*sin(freq*t*2*pi);
    elseif (val == 2),   % square wave
        tt=freq*t*2*pi;
        tmp=rem(tt,2*pi);
        f=amp*(2*rem((tt<0)+(tmp>pi | tmp<-pi)+1,2)-1);
    elseif (val == 3),   % sawtooth
        tt=freq*t*2*pi;
        f=amp*((tt < 0) + rem(tt,2*pi)/2/pi - .5)*2;
    end;
    set(time_line,'YData',f);
    F=fft(window.*f,2*M);
    F=F(1:M);
    w=(0:M-1)*pi/M;
    FF=20*log10(abs(F));
    ind=find(FF<min_dB);
    FF(ind)=NaN*ones(size(ind)); % put NaN's in where
             % min_dB shows up - this is to work around no clipping in xor mode
    set(freq_line,'YData',FF);
    set(freq_field,'String',num2str(freq));

    drawnow;

elseif strcmp(action,'setwindow'),
    % u = get(gcf,'userdata');
    winHndl = ADDIT_DAT;
    in1 = get(winHndl,'Value');
    in2 = 30;
    N=SIGDEMO1_DAT(3);

    if (in1==1),
        window = boxcar(N);
    elseif (in1==2),
        window = triang(N);
    elseif (in1==3),
        window = hanning(N);
    elseif (in1==4),
        window = hamming(N);
    elseif (in1==5),
        window = chebwin(N,30);
    elseif (in1==6),
        window = kaiser(N,4);
    end;

    SIGDEMO1_DAT(14+N:14+N+N-1)=window;
    % set(gcf,'userdata',u);
    sigdemo1('redraw');
    if (SIGDEMO1_DAT(12)~=-1),
        sigdemo1('showwind');
    end;

elseif strcmp(action,'showwind'),
    % u=get(gcf,'userdata');
    oldfig=gcf;
    N=SIGDEMO1_DAT(3);
    t=SIGDEMO1_DAT(14:14+N-1);
    window=SIGDEMO1_DAT(14+N:14+N+N-1);
    if (SIGDEMO1_DAT(12)==-1),
        SIGDEMO1_DAT(12)=figure;

        axes('Position',[.15 .62 .8 .3]);
        line1=plot(t,window); 
        title('Window function');
        xlabel('time (seconds)');
        grid on;
        ylabel('Window');

        axes('Position',[.15 .2 .8 .3]);
        W=fft(window,1024);
        line2=plot((0:(1/1024):(.5-(1/1024)))*N,20*log10(abs(W(1:512)))); 
        set(gca,'xlim',[0 N/2]);
        xlabel('Frequency (Hz)');
        ylabel('Magnitude (dB)');
        grid on;
        windclose=uicontrol('Style','Pushbutton','Units','Normalized',...
            'Position',[.85 .02 .12 .08],...
            'Callback',['THEHAND=get(gcf,''userdata'');'...
            'close; figure(THEHAND(1)); global SIGDEMO1_DAT, '...
            'SIGDEMO1_DAT(12)=-1; clear THEHAND SIGDEMO1_DAT'],...
            'String','Close');
        set(gcf,'userdata',[oldfig line1 line2]);
        % set(oldfig,'userdata',u);
        
    else
        figure(SIGDEMO1_DAT(12));
        lines=get(gcf,'userdata');
        set(lines(2),'ydata',window);
        W=fft(window,1024);
        set(lines(3),'ydata',20*log10(abs(W(1:512))));
        drawnow
    end

elseif strcmp(action,'setfreq'),
    x = str2num(get(SIGDEMO1_DAT(10),'string'));
    if isempty(x),   % handle the non-numeric case
        set(SIGDEMO1_DAT(10),'string',num2str(SIGDEMO1_DAT(1)));
    else
        SIGDEMO1_DAT(1)=x;
    end;

elseif strcmp(action,'info'),
    ttlStr = 'Discrete Fourier Transform'; 

    hlpStr1= ...                                              
        ['                                                '
         ' You are seeing discrete samples of a periodic  '  
         ' waveform (the upper plot) and the absolute     '  
         ' value of its discrete Fourier transform (DFT), '  
         ' obtained using a fast Fourier transform (FFT)  '  
         ' algorithm (the lower plot).                    '  
         '                                                '  
         ' In the lower plot, frequencies from 0 to       '  
         ' 100 Hertz are displayed. The DFT at negative   '  
         ' frequencies is a mirror image of the DFT at    '  
         ' positive frequencies.  The sampling rate is    '  
         ' 200 Hertz, which means the "Nyquist frequency" '  
         ' is 100 Hertz.  The DFT at frequencies above    '  
         ' the Nyquist frequency is the same as the DFT   '  
         ' at lower (negative) frequencies.               '];

    hlpStr2= ...                                               
        [' Click and drag a point on the waveform shown    '  
         ' in the upper plot to move that point to a new   '  
         ' location. This sets a new fundamental           '  
         ' frequency and amplitude.                        '  
         '                                                 '  
         ' The "Signal" pop-up menu lets you change the    '  
         ' shape of the waveform.                          '  
         '                                                 '  
         ' The "Window" menu lets you select a window      '  
         ' function. This window is multiplied by the time '  
         ' waveform prior to taking the DFT.               '  
         '                                                 '  
         ' The fundamental frequency of the waveform is    '  
         ' given in the text box.  You can change the      '  
         ' fundamental frequency by clicking in the text   '  
         ' box, editing the number there, and pressing     '  
         ' RETURN.  You can also change the                '  
         ' fundamental by clicking and dragging on the     '  
         ' waveform.                                       '];

     hlpStr3= str2mat(...                   
         ' ', ...
         ' File name: sigdemo1.m');

     helpfun(ttlStr, hlpStr1, hlpStr2, hlpStr3);

end