Spreadsheet Filtering by FFT Gaussian-based Convolution
  Filtering of digital signals is accomplished on an Excel spreadsheet using fast Fourier transform (FFT) convolution in which the kernel is either a Gaussian or a cosine modulated Gaussian. Pedagogical examples of low-pass and band-pass filtering are provided, and the practical value of the spreadsheet is illustrated with some cases involving an earthquake record generated by a folded pendulum seismometer. 
Randall D. Peters