Filter Butterworth

I have this script: Wp=?; Ws=0.6; Rp=?; Rs=?; [n,Wn] = buttord(Wp,Ws,Rp,Rs); [b,a] = butter(n,Wn,'low'); Ws know, how do I choose the Wp,Rp and Rs ? I apologize in advance if the question can be trivial, but I need help. Thank you for your attention and look forward to a reply soon.

Answer 1

[Thomas]

It will depend on what you are trying to do (low pass, highpass, band pass, band stop)

You have Ws hence your Wp will change depending on what kind of filter you want. More details about the specificatiosn and examples are given in the documentation

documentation: http://www.mathworks.com/help/toolbox/signal/ref/buttord.html

Wp-Passband corner frequency Wp, the cutoff frequency, is a scalar or a two-element vector with values between 0 and 1, with 1 corresponding to the normalized Nyquist frequency, π radians per sample.

Ws-Stopband corner frequency Ws, is a scalar or a two-element vector with values between 0 and 1, with 1 corresponding to the normalized Nyquist frequency.

Rp-Passband ripple, in decibels. This value is the maximum permissible passband loss in decibels.

Rs-Stopband attenuation, in decibels. This value is the number of decibels the stopband is down from the passband