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

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


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


Forrest Sheng Bao
Ph.D. student, Dept. of Computer Science
M.Sc. student, Dept. of Electrical & Computer Engineering
Rm 115, Experimental Sciences Building
Texas Tech University, USA

Forrest is an equal opportunity Email sender.
1. You are encouraged to use the language you prefer. Beyond English, I can
also read traditional/simplified Chinese and a bit German.
2. I will only send you files readable to free or open source software.
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