Inverse impulse invariance method
Convert digital filter with coefficients b and a to analog, conserving impulse response.
invimpinvar(b, ...) ## S3 method for class 'Arma' invimpinvar(b, ...) ## Default S3 method: invimpinvar(b, a, fs = 1, tol = 1e-04, ...)
b |
coefficients of numerator polynomial |
... |
additional arguments (not used) |
a |
coefficients of denominator polynomial |
fs |
sampling frequency (Default: 1 Hz) |
tol |
tolerance. Default: 0.0001 |
Because invimpinvar is generic, it can also accept input of class
Arma.
A list of class Arma containing numerator and
denominator polynomial filter coefficients of the A/D converted filter.
R.G.H. Eschauzier, reschauzier@yahoo.com,
Carne Draug, carandraug+dev@gmail.com.
Conversion to R by Geert van Boxtel, G.J.M.vanBoxtel@gmail.com
Thomas J. Cavicchi (1996) Impulse invariance and multiple-order poles. IEEE transactions on signal processing, Vol 40 (9): 2344–2347.
f <- 2 fs <- 10 but <- butter(6, 2 * pi * f, 'low', 's') zbut <- impinvar(but, fs) sbut <- invimpinvar(zbut, fs) all.equal(but, sbut, tolerance = 1e-7)
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