R/sweptsine.R

In sonicscrewdriver: Bioacoustic Analysis and Publication Tools

#' Generate a frequency-swept sine wave
#'
#' Generates a frequency swept sine wave and returns it as a Wave object or vector.
#'
#' @param f0 Start frequency
#' @param f1 End frequency
#' @param sweep.time Duration of swept wave
#' @param A Amplitude of wave
#' @param samp.rate Sample rate of swept wave
#' @param output "wave" for a Wave object, or "vector"
#' @param ... Additional arguments to pass to data2Wave
#' @export
#' @return A swept wave object of the type specified in output.
#' @examples
#' sweptsine()
#'
sweptsine <- function(f0=100, f1=2500, sweep.time=1, A=1, samp.rate=44100, output="wave", ...) {
  f <- f0
  phi <- 0 #Phase accumulator
  delta <- 2 * pi * f / samp.rate
  f_delta <- (f1 - f0) / (samp.rate * sweep.time)
  
  w <- vector(mode="numeric", length=samp.rate*sweep.time)
  
  i <- 1
  while (i < samp.rate*sweep.time) {
    w[i] <- A * sin(phi)
    phi <- phi + delta
    f <- f + f_delta
    delta <- 2 * pi * f / samp.rate
    i <- i+1
  }
  if (output == "vector") {
    return(w)
  }
  if (output == "wave") {
    return(data2Wave(w, samp.rate=samp.rate, ...))
  }
  
}