invimpinvar {gsignal}

Inverse impulse invariance method

Description

Convert digital filter with coefficients b and a to analog, conserving impulse response.

Usage

invimpinvar(b, ...)

## S3 method for class 'Arma'
invimpinvar(b, ...)

## Default S3 method:
invimpinvar(b, a, fs = 1, tol = 1e-04, ...)

Arguments

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

Details

Because invimpinvar is generic, it can also accept input of class Arma.

Value

A list of class Arma containing numerator and denominator polynomial filter coefficients of the A/D converted filter.

Author(s)

R.G.H. Eschauzier, [e-mail],
Carne Draug, [e-mail].
Conversion to R by Geert van Boxtel, [e-mail]

References

Thomas J. Cavicchi (1996) Impulse invariance and multiple-order poles. IEEE transactions on signal processing, Vol 40 (9): 2344–2347.

See Also

impinvar

Examples

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)