Hello, I recently performed a free vibrational analysis and these are the results https://drive.google.com/file/d/0B2F1liITq1icMlk1U05sMjktVWM/view?usp=sharing
When I perform the FFT analysis on it I get results far different than the calculated natural frequency (5.1Hz). I believe there is a mistake in my signal sampling. Can anyone help me with this? Thank you.
Code used for FFT analysis:
Fs=20;T=1/Fs;L=20;ctdata=load('Sravs3.dat');t=ctdata(:,1);y=ctdata(:,2);%plot(Fs*t(1:50),y(1:200))
title('signal in time domain')xlabel('time (ms)')ylabel('X{t}')NFFT=2^nextpow2(L);Y=fft(y,NFFT);f=Fs/2*linspace(0,1,NFFT/2);figurestem(f,2*abs(Y(1:NFFT/2)))title('Single-sided Amplitude Spectrum of y(t)')xlabel('Frequency(Hz)')ylabel('|Y(f)|')
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