📄 sigaxz1.m
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N=SIGAXZ1_DAT(3);
M=SIGAXZ1_DAT(4);
min_dB=SIGAXZ1_DAT(5);
fixed_x=SIGAXZ1_DAT(6);
fixed_y=SIGAXZ1_DAT(7);
time_line=SIGAXZ1_DAT(8);
freq_line=SIGAXZ1_DAT(9);
freq_field=SIGAXZ1_DAT(10);
popup=SIGAXZ1_DAT(11);
t=SIGAXZ1_DAT(14:14+N-1);
window=SIGAXZ1_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=SIGAXZ1_DAT(1);
amp=SIGAXZ1_DAT(2);
fixed_x=SIGAXZ1_DAT(6);
fixed_y=SIGAXZ1_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(SIGAXZ1_DAT(8),'linestyle','-','markersize',8);
SIGAXZ1_DAT(1)=freq1; % set amplitude and frequency
SIGAXZ1_DAT(2)=amp1;
% set(gcf,'userdata',u);
sigaxz1('redraw');
elseif strcmp(action,'done'),
% close the figure window that is showing the window fnction:
% u = get(gcf,'userdata');
show_window=findobj('Tag','window_window');
if ( ~isempty(show_window) & SIGAXZ1_DAT(12)~=-1 )
close(SIGAXZ1_DAT(12));
end;
close(gcf);
clear global SIGAXZ1_DAT
clear global ADDIT_DAT
clear global fun_str
clear show_window
elseif strcmp(action,'redraw'),
% recomputes time and frequency waveforms and updates display
% u = get(gcf,'userdata');
freq=SIGAXZ1_DAT(1);
amp=SIGAXZ1_DAT(2);
N=SIGAXZ1_DAT(3);
M=SIGAXZ1_DAT(4);
min_dB=SIGAXZ1_DAT(5);
time_line=SIGAXZ1_DAT(8);
freq_line=SIGAXZ1_DAT(9);
freq_field=SIGAXZ1_DAT(10);
popup=SIGAXZ1_DAT(11);
t=SIGAXZ1_DAT(14:14+N-1);
window=SIGAXZ1_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;
elseif (val == 4), % self-defined waveform
f=eval(fun_str);
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=SIGAXZ1_DAT(3);
show_window=SIGAXZ1_DAT(14+N+N);
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;
SIGAXZ1_DAT(14+N:14+N+N-1)=window;
% set(gcf,'userdata',u);
sigaxz1('redraw');
if get(show_window,'value'),
sigaxz1('showwin');
end;
elseif strcmp(action,'showwin'),
% u=get(gcf,'userdata');
oldfig=gcf;
N=SIGAXZ1_DAT(3);
t=SIGAXZ1_DAT(14:14+N-1);
window=SIGAXZ1_DAT(14+N:14+N+N-1);
if (SIGAXZ1_DAT(12)==-1),
SIGAXZ1_DAT(12)=figure('NumberTitle','off', ...
'Name','窗口', 'menubar','none',...
'Tag','window_window');
axes('Position',[.15 .62 .8 .3]);
line1=plot(t,window);
title('窗口函数');
xlabel('时间（秒）');
grid;
ylabel('窗口');
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('频率 (Hz)');
ylabel('幅度 (dB)');
grid;
windclose=uicontrol('Style','Pushbutton',...
'Position',[.85 .02 .12 .08],...
'Units','normalized',...
'String','关闭',...
'Callback',[...
'THEHAND=get(gcf,''userdata'');',...
'close;',...
'figure(THEHAND(1));',...
'global SIGAXZ1_DAT;',...
'SIGAXZ1_DAT(12)=-1;',...
'clear THEHAND SIGAXZ1_DAT;']);
set(gcf,'userdata',[oldfig line1 line2]);
% set(oldfig,'userdata',u);
clear line1 line2 W;
else
show_window=findobj('Tag','window_window');
if isempty(show_window)
SIGAXZ1_DAT(12)=-1;
sigaxz1('showwin');
else
figure(SIGAXZ1_DAT(12));
drawnow
lines=get(gcf,'userdata');
set(lines(2),'ydata',window);
W=fft(window,1024);
set(lines(3),'ydata',20*log10(abs(W(1:512))));
figure(SIGAXZ1_DAT(12));
drawnow;
clear W lines;
end
clear show_window;
end
clear oldfig N t window;
elseif strcmp(action,'delshow'),
N=SIGAXZ1_DAT(3);
show_window=SIGAXZ1_DAT(14+N+N);
if ( SIGAXZ1_DAT(12)~=-1 & get(show_window,'value')==0),
show_window=findobj('Tag','window_window');
if isempty(show_window)
SIGAXZ1_DAT(12)=-1;
else
figure(show_window);
THEHAND=get(gcf,'userdata');
close;
figure(THEHAND(1));
SIGAXZ1_DAT(12)=-1;
clear THEHAND;
end
end
clear show_window N;
elseif strcmp(action,'setfreq'),
x = str2num(get(SIGAXZ1_DAT(10),'string'));
if isempty(x), % handle the non-numeric case
set(SIGAXZ1_DAT(10),'string',num2str(SIGAXZ1_DAT(1)));
else
SIGAXZ1_DAT(1)=x;
end;
elseif strcmp(action,'info'),
ttlStr = '离散傅立叶变换（DFT）';
hlpStr1= ...
[' '
' 我们看到，在演示窗口中，上方的图表示了对一个周 '
' 期信号波形的离散抽样（抽样频率 Fs = 200 Hz）； '
' 下方的图给出了该离散信号的离散傅立叶变换（DFT）'
' 的绝对值。DFT的值由快速傅立叶变换算法（FFT）得 '
' 到。 '
' '
' 注意：下图中，频率范围是从 0 到 100 Hz。处于负 '
' 频域的 DFT 是正频域 DFT 的镜象，故在此只画出了 '
' 正频域的 DFT。抽样频率是 200Hz，这意味着“奈奎 '
' 斯特”频率是 100Hz。在高于“奈奎斯特”频率的频 '
' 率点处的 DFT 与在低频（负频域）处的DFT相同。 '
' '];
hlpStr2= ...
[' '
' 在上图中，点击并拖动信号波形上的任意一点，这样 '
' 可以设置信号的新的基频与幅度。 '
' '
' 选择下拉式菜单“信号”可改变信号的波形。 '
' '
' 菜单“窗口”让你选择一个窗口函数，在对信号进行 '
' DFT 以前，这个窗口将与信号波形相乘——即 '
' “开窗截取”。 '
' '
' 检查框“显示窗口函数”若被选中，则在显示信号波 '
' 形和其DFT的同时，也显示出窗口函数的形状。 '
' '
' 左边的文本框给出了信号的基频，可以通过用鼠标点 '
' 击此文本框，然后编辑频率值的大小，再回车来改变 '
' 信号的基频。 ' ];
hlpStr3= str2mat(...
' ', ...
' 文件名：sigaxz1.m');
helpwin(ttlStr, hlpStr1, hlpStr2, hlpStr3);
end
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