Elliptic or Cauer filter
Generate an Elliptic or Cauer filter (discrete and continuous).
## Default S3 method: ellip(n, Rp, Rs, W, type = c("low", "high", "stop", "pass"), plane = c("z", "s"), ...) ## S3 method for class 'FilterOfOrder' ellip(n, Rp = n$Rp, Rs = n$Rs, W = n$Wc, type = n$type, ...)
n |
filter order or generic filter model |
Rp |
dB of pass band ripple |
Rs |
dB of stop band ripple |
W |
critical frequencies of the filter. |
type |
Filter type, one of |
plane |
|
... |
additional arguments passed to |
Because ellip
is generic, it can be extended to accept other
inputs, using "ellipord"
to generate filter criteria for example.
An Arma
object with list elements:
b |
moving average (MA) polynomial coefficients |
a |
autoregressive (AR) polynomial coefficients |
Original Octave version by Paulo Neis p_neis@yahoo.com.br. Modified by Doug Stewart. Conversion to R by Tom Short.
Oppenheim, Alan V., Discrete Time Signal Processing, Hardcover, 1999.
Parente Ribeiro, E., Notas de aula da disciplina TE498 - Processamento Digital de Sinais, UFPR, 2001/2002.
Octave Forge http://octave.sf.net
# compare the frequency responses of 5th-order Butterworth and elliptic filters. bf <- butter(5, 0.1) ef <- ellip(5, 3, 40, 0.1) bfr <- freqz(bf) efr <- freqz(ef) plot(bfr$f, 20 * log10(abs(bfr$h)), type = "l", ylim = c(-50, 0), xlab = "Frequency, radians", ylab = c("dB")) lines(efr$f, 20 * log10(abs(efr$h)), col = "red")
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