1d:T7b3,# Draw the amplitude profile of a frequency filter This function lets the user drawing the amplitude profile of a frequency filter. ```r 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. ## Returns 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. ## Author(s) Laurent Lellouch ## Note This function can be used to prepare bandpass or bandstop custom filters to be used with `fir` and `ffilter`. See examples. ## See Also `fir`, `squarefilter`, `combfilter`, `ffilter`, `drawenv` ## Examples ```r ## 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) ```

drawfilter function