Dear all, I have some real data (about 32 equidistant points), and I fitted it a Fourier transform function using the FFT method. Indeed I get 32 complex Fourier coefficients, which correspond to the obtained 16 positive frequencies. I want to apply a low pass filter to smooth the obtained fitted function. Actually I take the fifth frequency as a low pass threshold (so I take only the first five frequencies which correspond to 30% of the total frequencies). I have chosen this threshold, basing on a visual interpretation of the fitted curve. Can anyone suggest a more robust or efficient method to choose the threshold frequency for low pass filter?
Dear Oussama Braydi
Basically, Low-pass filters always transition smoothly from the passband to the stopband. Furthermore, there is nothing magical about the “cutoff” frequency, which is more accurately referred to as the –3dB frequency, i.e., the frequency at which the magnitude response is 3 dB lower than the value at 0 Hz.
Kind Regards
Qamar Ul Islam
Have a look at https://www.youtube.com/watch?v=lagfhNjMuQM also https://www.allaboutcircuits.com/technical-articles/low-pass-filter-tutorial-basics-passive-RC-filter/
I suggest filter design Matlab tool
https://www.mathworks.com/discovery/filter-design.html
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