Compute discrete elliptic filter order and cutoff for the desired response
characteristics.
Usage
ellipord(Wp, Ws, Rp, Rs)
Arguments
Wp, Ws
pass-band and stop-band edges. For a low-pass or
high-pass filter, Wp and Ws are scalars. For a
band-pass or band-rejection filter, both are vectors of length
2. For a low-pass filter, Wp < Ws. For a
high-pass filter, Ws > Wp. For a band-pass (Ws[1] < Wp[1] < Wp[2] <
Ws[2]) or band-reject (Wp[1] < Ws[1] < Ws[2] < Wp[2])
filter design, Wp gives the edges of the pass band, and Ws gives
the edges of the stop band. Frequencies are normalized to [0,1],
corresponding to the range [0, Fs/2].
Rp
allowable decibels of ripple in the pass band.
Rs
minimum attenuation in the stop band in dB.
Value
An object of class FilterOfOrder with the following list elements:
n
filter order
Wc
cutoff frequency
type
filter type, one of "low", "high", "stop", or "pass"
Rp
dB of pass band ripple
Rs
dB of stop band ripple
This object can be passed directly to ellip to compute discrete filter coefficients.
Author(s)
Original Octave version by Paulo Neis
p_neis@yahoo.com.br.
Modified by Doug Stewart. Conversion to R by Tom Short.
References
Lamar, Marcus Vinicius, Notas de aula da disciplina TE 456 - Circuitos Analogicos II, UFPR, 2001/2002.