[help] FFT & Spectrogram

[Judd Storrs]

On Thu, Jul 2, 2009 at 2:01 AM, febty febriani <febty82 at gmail.com> 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
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