drawfilter {seewave}

Draw the amplitude profile of a frequency filter

Description

This function lets the user drawing the amplitude profile of a frequency filter.

Usage

drawfilter(f, n = 256, continuous = TRUE, discrete = TRUE)

Arguments

f

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

n

a numeric vector of length 1 for the length (i.e. number of points) of the filter. By default = 256 to fit with a FIR with wl = 512.

continuous

a logical (TRUE by default) to draw a continuous filter.

discrete

a logical (TRUE by default) to draw a discrete filter.

Details

If the same frequency of a discrete filter is selected twice then the sum of the amplitudes of the two selections is used. If both arguments continuous and discrete are set to TRUE and if frequencies selected overlap between the two filters then only the frequencies of the discrete filter are considered.

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.

Note

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

Author(s)

Laurent Lellouch

See Also

fir, squarefilter, combfilter, ffilter, drawenv

Examples

## Not run: 
f <- 8000
a <- noisew(f=f, d=1)
## bandpass continuous and discrete
cont.disc <- drawfilter(f=f/2)
a.cont.disc <- fir(a, f=f, custom=cont.disc)
spectro(a.cont.disc, f=f)
## bandpass continuous only
cont <- drawfilter(f=f/2, discrete=FALSE)
a.cont <- fir(a, f=f, custom=cont)
spectro(a.cont, f=f)
## bandstop continuous only
cont.stop <- drawfilter(f=f/2, discrete=FALSE)
a.cont.stop <- fir(a, f=f, custom=cont.stop, bandpass=FALSE)
spectro(a.cont.stop, f=f)
## bandpass discrete only
disc <- drawfilter(f=f/2, continuous=FALSE)
a.disc <- fir(a, f=f, custom=disc, bandpass=FALSE)
spectro(a.disc, f=f)

## End(Not run)