Hello,

I've imported a wav file into MATLAB as below: -

[X Fs nbits] = wavread ('file directory');

subplot(2,1,1);plot(X);
title('X(t)');
xlabel('Time (s)');
ylabel('Amplitude (V)');
grid on;

subplot(2,1,2);plot((abs(fft(X))));
title('X(f)');
xlabel('Frequency (Hz)');
ylabel('Power Spectral Density');
grid on;

How would I know if MATLAB is plotting the right length of time, frequency and PSD? Also I would like to prevent MATLAB from plotting the negative frequencies.

Thanks

 

The sample rate and other information is in the wav header
https://ccrma.stanford.edu/courses/422/projects/WaveFormat/
Sorry can not help you with the Matlab question

 

mean change axis xmin=0
axis([xmin xmax ymin ymax])

or not calculate them at all. this would be hard.

 

Thanks for the reply.

I found this online: - http://www.prism.gatech.edu/~jrossi3/guides/sound/fft.pdf

It seems to be doing what I'm looking for.