Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!ogicse!usenet!jacobs.CS.ORST.EDU!cosgrok From: cosgrok@jacobs.CS.ORST.EDU (Kevin Cosgrove) Newsgroups: comp.dsp Subject: Re: Why Don't My FFT Deconvolutions Work!! Message-ID: <1991Feb14.042835.5631@lynx.CS.ORST.EDU> Date: 14 Feb 91 04:28:35 GMT References: <1991Feb9.034956.7993@bilver.uucp> Sender: @lynx.CS.ORST.EDU Distribution: na Organization: Oregon State University, CS Dept. Lines: 25 Nntp-Posting-Host: jacobs.cs.orst.edu In article <1991Feb9.034956.7993@bilver.uucp> alex@bilver.uucp (Alex Matulich) writes: [stuff deleted] >You will recall that the deconvolution of a function f with a response >function g is > >F(f decon g) = F(f) / F(g) > >where F() is the Fourier transform. See the problem? You have to DIVIDE >by the Fourier transform of g. In all my experiments, for any response >function I try, F(g) is zero somewhere (or near zero) which completely >messes up the result. Don't get too frustrated. We don't want to see you end up in a hospital or anything -- geese that's it! Could l'Hopital's rule help evaluate the function when the denominator goes to zero? If that doesn't work, you might try _Discrete-Time_Signal_Processing by Oppenheim and Schafer via Prentice-Hall Pub. as a reference. Chapter 12 covers deconvolution directly in the time domain, which could even be faster while inducing less noise -- but I'm not sure since I won't get to that chapter 'til next term. __ -- Kevin Cosgrove