I have the signal shown at the attached image. I want to remove the chattering which I think is high-frequency compared to the signal of interest. So, I think I should use some kind of low pass filter to filter out this chattering. In order to design an optimal filter should I firstly perform a Fourier transform to identify the frequency band of the signal and the frequency band of the noise ? And considering I perform the Fourier transform using Matlab’s fft(X), how do I recognize these frequency bands and then design the appropriate filter ?