ellipord {signal} | R Documentation |
Compute discrete elliptic filter order and cutoff for the desired response characteristics.
ellipord(Wp, Ws, Rp, Rs)
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. |
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.
Original Octave version by Paulo Neis p_neis@yahoo.com.br. Modified by Doug Stewart. Conversion to R by Tom Short.
Lamar, Marcus Vinicius, Notas de aula da disciplina TE 456 - Circuitos Analogicos II, UFPR, 2001/2002.
Octave Forge http://octave.sf.net
Arma
, filter
, butter
,
cheby1
, and ellipord
Fs = 10000 elord = ellipord(1000/(Fs/2), 1200/(Fs/2), 0.5, 29) plot(c(0, 1000, 1000, 0, 0), c(0, 0, -0.5, -0.5, 0), type = "l", xlab = "Frequency (Hz)", ylab = "Attenuation (dB)") el1 = ellip(elord) plot(c(0, 1000, 1000, 0, 0), c(0, 0, -0.5, -0.5, 0), type = "l", xlab = "Frequency (Hz)", ylab = "Attenuation (dB)", col = "red", ylim = c(-35,0), xlim = c(0,2000)) lines(c(5000, 1200, 1200, 5000, 5000), c(-1000, -1000, -29, -29, -1000), col = "red") hf = freqz(el1, Fs = Fs) lines(hf$f, 20*log10(abs(hf$h)))