ellipord: Elliptic filter order and cutoff

View source: R/ellipord.R

ellipordR Documentation

Elliptic filter order and cutoff


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].


allowable decibels of ripple in the pass band.


minimum attenuation in the stop band in dB.


An object of class FilterOfOrder with the following list elements:


filter order


cutoff frequency


filter type, one of "low", "high", "stop", or "pass"


dB of pass band ripple


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 https://octave.sourceforge.io/

See Also

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)))

signal documentation built on June 26, 2024, 9:06 a.m.

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