[SciPy-user] normalized frequencies to pi radians / sample

Forrest Sheng Bao forrest.bao@gmail....
Tue Mar 18 14:08:36 CDT 2008

```Hi,

I am trying to use buttord function to compute the order and frequency of a
Butterworth filter.

But I got confused about the passband and stopband edge frequency. According
to the doc,

wp, ws -- Passband and stopband edge frequencies, normalized from 0
to 1 (1 corresponds to pi radians / sample).  For example:
Lowpass:   wp = 0.2,          ws = 0.3
Highpass:  wp = 0.3,          ws = 0.2
Bandpass:  wp = [0.2, 0.5],   ws = [0.1, 0.6]
Bandstop:  wp = [0.1, 0.6],   ws = [0.2, 0.5]

I should normalize the frequency to pi radians / sample. Now, suppose a
frequency 10Hz and my sampling rate is 100 Hz. Is the normalized frequency
0.1?

Thanks,
Forrest

--
Forrest Sheng Bao
Ph.D. student, Dept. of Computer Science
M.Sc. student, Dept. of Electrical & Computer Engineering
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