squarefilter {seewave}

Frequency square filter

Description

This function prepares the amplitude profile of a square frequency filter.

Usage

squarefilter(f, from = NULL, to = NULL, bandpass = TRUE, wl = 1024)

Arguments

f

a numeric vector of length 1 for the sampling frequency of the object to be filtered (in Hz).

from

a numeric vector for the start frequencies (in Hz) where to apply the filter.

to

a numeric vector of the end frequencies (in Hz) where to apply the filter.

bandpass

if TRUE a band-pass filter is prepared between start and end frequencies (arguments from and to), if FALSE a bandstop filter is prepared.

wl

window length of the impulse filter (even number of points).

Value

The function returns a two-column matrix, the first column is the frequency in kHz and the second column is the amplitude of the filter (frequency response of the filter).

Note

This function can be used to prepare bandpass or bandstop filters to be used with fir and ffilter. See examples.

Author(s)

Laurent Lellouch

See Also

fir, drawfilter, ffilter, combfilter, bwfilter

Examples

f <- 44100
a <- noisew(f = f, d = 1)
p <- squarefilter(f, from = c(100, 1000, 4000), to = c(500, 3000, 8000))
plot(p, type="l")
h <- fir(a, f = f, custom = p, wl = 1024, output = 'Wave')
spectro(h)