1
$\begingroup$

I am trying to design a IIR to remove the noise from my input signal. Here is my the my input signal in the frequency domain enter image description here

And here is the noise in the frequency domain that, enter image description here

So I may choose approximately 60Hz (might be wrong) as the cutoff frequency based on these two figures, but how should I calculate it?

$\endgroup$

1 Answer 1

1
$\begingroup$

For filter design, the passband is selected to pass all signals of interest, and the stopband is chosen to select all signals to be rejected. The complexity of the filter is driven by how much distortion to allow in the passband (typically given as a "passband ripple" as a deviation from the ideal "1", how much rejection is required in the stopband, and how much of a transition is given between passband and stopband.

filter specification

I recommend plotting the magnitude of the spectrums in dB, which will make the distinction between passband and stopband clearer, and allow for reasonable filter design requirements in dB.

This forms the primary trade space of filter design: given the three parameters: filter order, the passband and stopband ripple, and the transition width you can improve two of these at the expense of the third.

For FIR filter design specifically, please see this post on estimating the order required based on the attenuation needed and transition band between passband and stopband.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.