FILTER ANALYSIS USING FAST FOURIER TRANSFORM

Abstract

The two important tools for digital signal processing are- digital filters and fast Fourier transform. The primair objet is to develOp the basic computa tional procedure for aluating discrete Fourier transform for the filter analysis. For this purpose the fast Fourier transform (FFT) is used, whiOh is a high speed algorithm for comp.tthg the Fourier transform of a discrete time Signi The FET has made it posible to compute the Fourier transform of signal containing thousands of Points in a matter of milliseconds, Digital signal processing has witnessed tremendous growth in the past, few years. Although, ultimate gd:k is that of digital processing analog filter functions are used as prototype models for developing digital filters. The lowpass filter is used as a basis for developing, approximate functjOflS for its simplicity, There are transfoimationS available that permit one to 1map1 a lowp'ass form into either a bandpa5s bandiejOOtion or highpass form, and these three ttansfOrmatioflS have been explored in this work, Filter analt'i has bcome very simple due to the convolution property of Fourier transform. The driving f'unô-tlons are generated in the frequenCy domain to- rô'&iCe the: time required for filter' anaJyiS., Here the delay charac-. teri5'tiG of the filter is' also discussed,