MATLAB: Butterworth band pass filter

band pass filteringbutterworth

hi, i want to design a butterworth bandpass filter with this specification: sample rate=250 Hz, low and high cutoff frequency=8-30 Hz, order=5

i wrote below commands but i'm not sure it is true.is it true?

[b,a] = butter(5,[8 30]/125,'bandpass');

can anybody help me?

According to the documentation, this is correct: doc butter (link)

See https://www.mathworks.com/matlabcentral/answers/273811-butterworth-filtering-with-bandpass-and-3-order

Hi Federico,

Butterworth filter is an IIR filter, so you will need to get the denominator too, i.e., using the syntax

[B,A] = butter(order,[f1/(rate/2) f2/(rate/2)]);

There are several ways you can visualize the response. I would recommend to use fvtool, e.g.,

fvtool(B,A)

You can also do

freqz(B,A)

if you want.

HTH,

Honglei