To obtain spectral density from a fast Fourier transform (FFT) of a signal, the magnitude squared of the FFT is typically used, along with a scaling factor. The discussion emphasizes the importance of understanding power spectrum and energy spectrum, which relate to the Fourier Transform of the autocorrelation function. For practical implementation, some participants are considering using software, while others are interested in coding solutions in Fortran 90. A reference to Tom Irvine's work at VibrationData.com is suggested for further reading on the topic. The main challenge highlighted is the correct application of the scaling factor in the calculations.
