code: def linear_chirp(npts=2000):
      
      time = np.linspace(0, 20, npts)
      chirp = np.sin(0.2 * np.pi * (0.1 + 24.0 / 2.0 * time) * time)
      return chirp
docs: Generates a simple linear chirp.
  
      :param npts: Number of samples.
      :type npts: int
      :returns: Generated signal
      :rtype: numpy.ndarray