sigaxz1.m

信号实验常用的simulink模型和mfile,可直接在matlan下运行。

function sigaxz1(action,in1,in2);
%SIGAXZ1 交互式信号演示 - 1 : 信号的 DFT
%	Illustrating some basic signal processing concepts, such as 
%	sampling, aliasing, and windowing.

%	possible actions:
%	  'start'
%	  'down'
%	  'move'
%	  'up'
%	  'redraw'
%	  'done'
%	  'setfreq'
%	  'setwindow'
%	  'showwin'

if nargin<1,
    action='start';
end;

global SIGAXZ1_DAT
global ADDIT_DAT	% this is for WINDOW pop-up button
global fun_str

if strcmp(action,'start'),

    %====================================
    % Graphics initialization
    oldFigNumber = watchon;
    figNumber = figure;
    set(gcf, ...
        'NumberTitle','off', ...
        'Name','离散傅立叶变换', ...
        'backingstore','off',...
        'Units','normalized');

    %====================================
    % Information for all buttons
    labelColor=192/255*[1 1 1];
    top=0.95;
    bottom=0.05;
    left=0.75;
    yInitLabelPos=0.90;
    left = 0.78;
    labelWid=0.18;
    labelHt=0.05;
    btnWid = 0.18;
    btnHt=0.07;
    % Spacing between the label and the button for the same command
    btnOffset=0.003;
    % Spacing between the button and the next command's label
    spacing=0.05;
 
    %====================================
    % The CONSOLE frame
    frmBorder=0.02;
    yPos=0.05-frmBorder;
    frmPos=[left-frmBorder yPos btnWid+2*frmBorder 0.9+2*frmBorder];
    h=uicontrol( ...
        'Style','frame', ...
        'Units','normalized', ...
        'Position',frmPos, ...
        'BackgroundColor',[0.5 0.5 0.5]);
    
    %====================================
    % The SIGNAL command popup button

    btnNumber=1;
    yLabelPos=top-(btnNumber-1)*(btnHt+labelHt+spacing);
    labelStr=' 信号';

    % Generic label information
    labelPos=[left yLabelPos-labelHt labelWid labelHt];
    uicontrol( ...
        'Style','text', ...
        'Units','normalized', ...
        'Position',labelPos, ...
        'BackgroundColor',labelColor, ...
        'HorizontalAlignment','left', ...
        'String',labelStr);

    btnPos=[left yLabelPos-labelHt-btnHt-btnOffset btnWid btnHt];
    popup=uicontrol('Style','Popup','String','正弦波|矩形波|锯齿波|自定义',...
        'Position', btnPos, ...
        'BackgroundColor','w', ...
        'ForegroundColor','k', ...
        'Units','normalized',...
        'CallBack',[...
		'global SIGAXZ1_DAT;',...
		'popup=SIGAXZ1_DAT(11);',...
		'val = get(popup,''Value'');',...
		'if val<=3',...
		'	sigaxz1(''redraw'');',...
		'else',...
		'	getstr;',...
		'end']);

    %====================================
    % The WINDOW command popup button
    btnNumber=2;
    yLabelPos=top-(btnNumber-1)*(btnHt+labelHt+spacing);
    labelStr=' 窗口函数';
    popupStr= '矩形|三角形|汉宁|海明';
    if ~isstudent
        popupStr= [popupStr '|切比雪夫|恺撒'];
    end
    callbackStr= 'sigaxz1(''setwindow'')';

    % Generic label information
    labelPos=[left yLabelPos-labelHt labelWid labelHt];
    uicontrol( ...
        'Style','text', ...
        'Units','normalized', ...
        'Position',labelPos, ...
        'BackgroundColor',labelColor, ...
        'HorizontalAlignment','left', ...
        'String',labelStr);

    % Generic popup button information
    btnPos=[left yLabelPos-labelHt-btnHt-btnOffset btnWid btnHt];
    winHndl = uicontrol( ...
        'Style','popup', ...
        'Units','normalized', ...
        'BackgroundColor','w', ...
        'ForegroundColor','k', ...
        'Position',btnPos, ...
        'String',popupStr, ...
	'visible','on',...
        'Callback',callbackStr);

  %====================================
    % The FUNDAMENTAL editable text box
    btnNumber=3;
    yLabelPos=top-(btnNumber-1)*(btnHt+labelHt+spacing);
    labelPos=[left yLabelPos-labelHt labelWid+0.02 labelHt];
    freq_text = uicontrol( ...
        'Style','text', ...
        'Position', labelPos, ...
        'Units','normalized', ...
        'BackgroundColor',[0.5 0.5 0.5], ...
        'ForegroundColor','w', ...
        'HorizontalAlignment','left', ...
        'String','基波频率：(Hz)');

    btnPos=[left+0.02  yLabelPos-labelHt-btnHt-btnOffset ...
            0.5*btnWid+frmBorder  btnHt];
    freq_field = uicontrol( ...
        'Style','edit', ...
        'BackgroundColor','w', ...
        'ForegroundColor','k', ...
        'Position', btnPos, ...
        'Units','normalized', ...
        'HorizontalAlignment','left', ...
        'String','5',...
        'CallBack','sigaxz1(''setfreq''); sigaxz1(''redraw'')');

   %====================================
    % The Show Window CheckBox
    show_window=uicontrol(gcf, ...
        'Style','checkbox', ...
        'Units','normalized',...
	'Position',[left yLabelPos-labelHt*4.5 labelWid+0.02 labelHt],...
	'backgroundcolor',[0.5 0.5 0.5],...
	'foregroundcolor','w',...
        'HorizontalAlignment','left', ...
        'string','显示窗口函数',...
	'value',0,...
        'Callback','sigaxz1(''delshow'');');

   %====================================
    % The INFO button
    uicontrol( ...
        'Style','push', ...
        'Units','normalized', ...
        'Position',[left bottom+(2*labelHt)+spacing btnWid 2*labelHt], ...
        'String','信息', ...
        'Callback','sigaxz1(''info'')');

   %========================================
   % The CLOSE button
    done_button=uicontrol('Style','Pushbutton', ...
        'Position',[left bottom btnWid 2*labelHt], ...
        'Units','normalized','Callback',...
        'sigaxz1(''done'')','String','关闭');
   %====================================

    % Create intial signal
    N=201;     % number of samples
%    N=21;
    amp=0.5;
    freq=5;    % hertz
    t0=0;      % seconds
    t1=1;      % seconds
    t=linspace(t0,t1,N)';
    T=(t1-t0)/N;            % sampling rate in seconds
    M=256;     % length of fft
    window=ones(N,1);    % use window to lower side-lobes in the freq. domain
                             % (makes peaks wider)

    min_dB = -40; % freq. domain lower axis limit

    % create axes for time domain and frequency domain plot
    ax_freq=axes('Position',[.12 .14 .6 .3],'XLim',...
             [0 1/(2*T)],'YLim',[min_dB 50]);
    
    % time domain
    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;
    elseif (val == 4),   % self-defined waveform
	f=eval(fun_str);
    end;

    % frequency domain
    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
    freq_line=plot(w/2/pi/T,FF,'EraseMode','xor');
    axis([0 1/(2*T)  min_dB 50]);
    grid;
    ylabel('幅度 (dB)');
    xlabel('频率 (Hz)');

    ax_time=axes('Position',[.12 .58 .6 .3],'XLim',[t0 t1],'YLim',[-1 1]);
    time_line=plot(t,f,'-','markersize',8,'EraseMode','xor');
    axis([t0 t1 -1 1]);
    % (set to xor mode to prevent re-rendering, that is, for speed)
    grid;
    ylabel('波形');
    xlabel('时间（秒）');
    text(0.05, 1.55,'点击并拖放信号波形以改变其基频与振幅。');

    set(time_line,'ButtonDownFcn','sigaxz1(''down'')');

    SIGAXZ1_DAT = [freq; amp; N; M; min_dB; 0; 0; ...
		time_line; freq_line; freq_field; popup; -1; gcf; ...
		t(:); window(:); show_window];
    ADDIT_DAT = winHndl;

    watchoff(oldFigNumber);

elseif strcmp(action,'down'),

  popup=SIGAXZ1_DAT(11);
  val = get(popup,'value');
  if val<=3
    % assumes that a line was clicked
    time_line=SIGAXZ1_DAT(8);
    axes(get(time_line,'parent'));	% set the right axes

    % Obtain coordinates of mouse click location in axes units
    pt=get(gca,'currentpoint');
    x=pt(1,1);
    y=pt(1,2);


% find closest vertex of line to mouse click location (call it fixed_x, fixed_y)

    line_x=get(time_line,'XData');
    line_y=get(time_line,'YData');
    units_str = get(gca,'units');  % save normalized state
    set(gca,'units','pixels');     % distance must be in pixels
    p=get(gca,'pos');
    xa=get(gca,'xlim');
    ya=get(gca,'ylim');
    
    dist=((line_x-x)*p(3)/(xa(2)-xa(1))).^2 + ...
         ((line_y-y)*p(4)/(ya(2)-ya(1))).^2;
    [temp,i]=min(dist);
    fixed_x=line_x(i);
    fixed_y=line_y(i);
    set(time_line,'LineStyle',':');

    SIGAXZ1_DAT(6)=fixed_x;
    SIGAXZ1_DAT(7)=fixed_y;

    set(gca,'units',units_str );
    set(gcf,'WindowButtonMotionFcn', 'sigaxz1(''move'')');
    set(gcf,'WindowButtonUpFcn', 'sigaxz1(''up'')');
    % set(gcf,'userdata',u);
end

elseif strcmp(action,'move'),
    % u = get(gcf,'userdata');
    freq=SIGAXZ1_DAT(1);
    amp=SIGAXZ1_DAT(2);