www.pudn.com > stft.rar > stft.m

load mtlb 
load mtlb; 
x=mtlb; 
figure(1) 
plot(0:4000,x); 
xlabel('n'); 
ylabel('x(n)'); 
title('random unbalanced signal x'); 
 
n0=0; 
R=128; 
n1=4000; 
n2=n0+R; 
n=[n0:n1]; 
w=[(n-n0)>=0]; 
wd=[(n-n2-1)<=0]; 
WN=w.*wd; 
figure(2) 
stem(n,WN); 
xlabel('n'); 
ylabel('W(N)'); 
title('Rectangular Window WN'); 
grid 
 
x1=x'; 
y1=x1.*WN; 
figure(3) 
plot(n,y1); 
xlabel('n'); 
ylabel('y1'); 
title('The first block') 
 
k=1:128; 
y3=[y1(n0+1:n2)]; 
figure(4) 
plot(k,y3); 
xlabel('k'); 
ylabel('y3'); 
title('The effective signal') 
 
yn=fft(y3); 
YN=abs(yn); 
figure(5) 
plot(k,YN); 
xlabel('frequency(Hz)'); 
ylabel('Abs'); 
title('Frequency content of yn'); 
 
for i=1:60 
    n2=n2+64; 
    n3=n0+i*64; 
    n=[n0:n1]; 
    w=[(n-n3)>=0]; 
    wd=[(n-n2)<=0]; 
    WN=w.*wd; 
    x1=x'; 
    y1=x1.*WN; 
    m=0:128; 
    y2=[y1(n3:n2)]; 
    figure(i+5) 
    plot(m,y2); 
    xlabel('m'); 
    ylabel('y2'); 
    title('Every signal signal'); 
    ym=fft(y2); 
    YM=abs(ym); 
    figure(i+5+60) 
    plot(m,YM); 
    xlabel('frequency(Hz)'); 
    ylabel('Abs'); 
    title('frequency content of ym'); 
end