FFT function from raw sound pressure data
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Hi,
I have some raw time vs sound pressure data that I would like to perform an FFT on and display as a frequency spectrum graph. I am struggling with how to get the correct frequency vector.
My data appears as: time = [0 1 2 3 4...] with corresponding sound pressure levels [5 34 23...]
Any help would be greatly appreciated.
Thanks for your time, Sam.
1 个评论
Youssef Khmou
2013-3-6
compare the code below with this command :
>>figure, psd(p) % with p sound pressure
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Youssef Khmou
2013-3-6
hi Sam, try this code .
% Given you vector p and time .
Fs=1; % sampling frequency.
L=length(p);
N=ceil(log2(L));
fp=fft(p,2^N)/(L/2);
Power=fp.*conj(fp);
f=(Fs/2^N)*(0:2^(N-1)-1);
plot(f,Power(1:2^(N-1)),'r'), xlabel(' Frequency (Hz)'), ylabel(' Magnitude (w)'),
title(' Power Spectral Density'), grid on;
4 个评论
Sam
2013-3-6
Sam
2013-3-6
Youssef Khmou
2013-3-6
in the first case the magnitude is simply in volts, or depends on what unis you are using , Pascal , Bar...but to plot in dB then :
semilogy(f,Power(1:2^(N-1)),'r'), xlabel(' Frequency (Hz)'), ylabel(' Magnitude (dB)'),
title(' Power Spectral Density, logarithmic scale '), grid on;
Sam
2013-3-6
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