Chebyshev Type I filter design
Compute the transfer function coefficients of a Chebyshev Type I filter.
cheby1(n, ...)
## S3 method for class 'FilterSpecs'
cheby1(n, ...)
## Default S3 method:
cheby1(
n,
Rp,
w,
type = c("low", "high", "stop", "pass"),
plane = c("z", "s"),
output = c("Arma", "Zpg", "Sos"),
...
)n |
filter order. |
... |
additional arguments passed to |
Rp |
dB of passband ripple. |
w |
critical frequencies of the filter. |
type |
filter type, one of |
plane |
"z" for a digital filter or "s" for an analog filter. |
output |
Type of output, one of:
Default is |
Chebyshev filters are analog or digital filters having a steeper roll-off than Butterworth filters, and have passband ripple (type I) or stopband ripple (type II).
Because cheby1 is generic, it can be extended to accept other inputs,
using cheb1ord to generate filter criteria for example.
Paul Kienzle, pkienzle@users.sf.net,
Doug Stewart, dastew@sympatico.ca.
Conversion to R Tom Short,
adapted by Geert van Boxtel, G.J.M.vanBoxtel@gmail.com.
## compare the frequency responses of 5th-order
## Butterworth and Chebyshev filters.
bf <- butter(5, 0.1)
cf <- cheby1(5, 3, 0.1)
bfr <- freqz(bf)
cfr <- freqz(cf)
plot(bfr$w / pi, 20 * log10(abs(bfr$h)), type = "l", ylim = c(-40, 0),
xlim = c(0, .5), xlab = "Frequency", ylab = c("dB"))
lines(cfr$w / pi, 20 * log10(abs(cfr$h)), col = "red")
# compare type I and type II Chebyshev filters.
c1fr <- freqz(cheby1(5, .5, 0.5))
c2fr <- freqz(cheby2(5, 20, 0.5))
plot(c1fr$w / pi, abs(c1fr$h), type = "l", ylim = c(0, 1),
xlab = "Frequency", ylab = c("Magnitude"))
lines(c2fr$w / pi, abs(c2fr$h), col = "red")Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.