stepR (version 1.0-1)

dfilter: Digital filters

Description

Create digital filters.

Usage

dfilter(type = c("bessel", "gauss", "custom"), param = list(pole = 4, cutoff = 1 / 10),
  len = ceiling(3/param$cutoff))
## S3 method for class 'dfilter':
print(x, \dots)

Arguments

type

allows to choose Bessel, Gauss or custom filters

param

for a "bessel" filter a list with entries pole and cutoff giving the filter's number of poles (order) and cut-off frequency, resp.; for a "gauss" filter the

len

filter length (unnecessary for "custom" filters

x

the object

...

for generic methods only

Value

• Returns a list of class dfilter that contains elements kern and step, the (digitised) filter kernel and step-response, resp., as well as an element param containing the argument param, for a "bessel" filter alongside the corresponding analogue kernel, step response, power spectrum, and autocorrelation function depending on time or frequency as elements kernfun, stepfun, spectrum, and acfun, resp.

See Also

filter, convolve, BesselPolynomial, Normal, family

Examples

# 6-pole Bessel filter with cut-off frequency 1 / 100, with length 100 (too short!)
dfilter("bessel", list(pole = 6, cutoff = 1 / 100), 100)
# custom filter: running mean of length 3
dfilter("custom", rep(1, 3))
dfilter("custom", rep(1, 3))$kern # normalised!
dfilter("custom", rep(1, 3))$step
# Gaussian filter with bandwidth 3 and length 11 (from -5 to 5)
dfilter("gauss", 3, 11)