cheb1ord function

Chebyshev Type I filter order

Compute Chebyshev type-I filter order and cutoff for the desired response characteristics.

cheb1ord(Wp, Ws, Rp, Rs, plane = c("z", "s"))

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. For digital filters, frequencies are normalized to [0, 1], corresponding to the range [0, fs/2]. In case of an analog filter, all frequencies are specified in radians per second.
• Rp: allowable decibels of ripple in the pass band.
• Rs: minimum attenuation in the stop band in dB.
• plane: "z" for a digital filter or "s" for an analog filter.

Returns

A list of class 'FilterSpecs' with the following list elements:

• n: filter order
• Wc: cutoff frequency
• type: filter type, normally one of "low", "high", "stop", or "pass".

Examples

## low-pass 30 Hz filter
fs <- 128
spec <- cheb1ord(30/(fs/2), 40/(fs/2), 0.5, 40)
cf <- cheby1(spec)
freqz(cf, fs = fs)

See Also

cheby1

Author(s)

Paul Kienzle, Laurent S. Mazet, Charles Praplan.

Conversion to R by Tom Short, adapted by Geert van Boxtel, G.J.M.vanBoxtel@gmail.com .