I've never used the matlab dsp toolkit, so what do I know..<BR><BR>Anyway, you might check out if octave-forge has something suitable (it's on sourceforge iirc). Or then scilab might have ...

Power-spectral plots generated by frequency sweeps or fast Fourier transforms (FFTs) can show you a signal’s frequency content, but sometimes an FFT provides more detail than you need. If you design ...