impz {gsignal}

Impulse response of digital filter

Description

Compute the z-plane impulse response of an ARMA model or rational IIR filter. A plot of the impulse and step responses is generated.

Usage

impz(filt, ...)

## S3 method for class 'impz'
print(x, ...)

## S3 method for class 'Arma'
impz(filt, ...)

## S3 method for class 'Ma'
impz(filt, ...)

## S3 method for class 'Sos'
impz(filt, ...)

## S3 method for class 'Zpg'
impz(filt, ...)

## Default S3 method:
impz(filt, a = 1, n = NULL, fs = 1, ...)

Arguments

filt

for the default case, the moving-average coefficients of an ARMA model or filter. Generically, filt specifies an arbitrary model or filter operation.

...

for methods of freqz, arguments are passed to the default method. For plot.impz, additional arguments are passed through to plot.

x

object to be printed or plotted.

a

the autoregressive (recursive) coefficients of an ARMA filter.

n

number of points at which to evaluate the frequency response. If n is a vector with a length greater than 1, then evaluate the frequency response at these points. For fastest computation, n should factor into a small number of small primes. Default: 512.

fs

sampling frequency in Hz. If not specified (default = 2 * pi), the frequencies are in radians.

Value

For impz, a list of class "impz" with items:

x

impulse response signal.

t

time.

Note

When results of impz are printed, plot will be called to display a plot of the impulse response against frequency. As with lattice plots, automatic printing does not work inside loops and function calls, so explicit calls to print or plot are needed there.

Author(s)

Paul Kienzle, [e-mail].
Conversion to R by Tom Short;
adapted by Geert van Boxtel, [e-mail]

Examples

## elliptic low-pass filter
elp <- ellip(4, 0.5, 20, 0.4)
impz(elp)

xt <- impz(elp)