FFT denoising vs low pass filter

Asked Apr 21 '22 at 03:14

Active Apr 21 '22 at 03:14

Viewed 829 times

Say I have a noisy signal in which I want to denoise.

There's two methods I'm considering

FFT denoising, where I take the FFT of the signal and then threshold somewhere, attenuate all the frequencies below this threshold, and then take the IFFT.
Low pass filtering, which in the Fourier domain is just attenuating all the frequencies above a particular frequency anyway.

My question is, what's the difference? Aren't we effectively selecting the frequencies we want at the end of the day? When would I prefer one over the other? I can only think using FFT denoising if we know the noise spans ALL of the spectrum including the lower frequencies.

asked Apr 21 '22 at 03:14

Nobody Special

3

Does this answer your question? Why is it a bad idea to filter by zeroing out FFT bins? – Dan Boschen Apr 21 '22 at 04:05
You shouldn't completely remove frequency components (as mentioned by Dan), this will cause a lot of "musical noise" in your output signal. Instead you should apply use a maximum attenuation of your signal as the floor for reduced noise. Spectral subtraction algorithm is probably what you have in your mind. – jojeck Apr 27 '22 at 14:14

FFT denoising vs low pass filter

0 Answers0