Re: [help] FFT & Spectrogram

[Judd Storrs]

On Thu, Jul 2, 2009 at 2:01 AM, febty febriani <address@hidden> wrote:

octave <<EOF
Fs=1;                          
fh=fopen("result.dat","r");
x=fscanf(fh,"%lf");
x0=hanning(4096);                  
a=(x(1:4096)).*(x0);                  
b=fft(a,8192);                      
c=abs(b(1:4096));
c=c/max(max(c))    ;                  
d=((1:4096)/4096)*(Fs/2);                                      
subplot(2,1,1);plot(d,c);
subplot(2,2,1);imagesc(flipud(20*log10(c)));
EOF

What I suspect is happening here is when octave reaches the EOF it exits and doesn't draw the plots. Since there also aren't any commands to save the plots to a file that is why you don't see any output. You can perhaps add a "print" statement to get the plots to file http://www.network-theory.co.uk/docs/octave3/octave_163.html

Or if you would rather watch the plots you can add

drawnow ;
sleep(10) ;

before the EOF to pause 10 seconds before exiting. For the second subplot you may want "subplot(2,1,2)" instead of "subplot(2,2,1)"

Hope this helps,

--judd