Article View: comp.dsp
Article #433FFT for integer data
From: William J. Murphy
Date: Wed, 04 Oct 1989 16:18
Date: Wed, 04 Oct 1989 16:18
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1719 bytes
I have a few questions for the dsp experts and amateurs.
I acquire data from two microphones and end up with a file that will
contain N 16-bit samples of the microphone voltages. Since the data is
real, I am considering crunching it with an FFT routine as described by
NUMERICAL Recipes for putting one sequence in the real part of the array and
the other sequence in the complex part. This should half the calculation
time of the FFT.
I have already copied/programmed the FFT routines in pascal/Turbo-Pascal
on a PC, but what I am wondering is if NR's procedure is particularly
fast or slow. I do know that there is a difference in speed between
Microsoft C and TP5.0 of about 2x for doing Mandelbrot calculations for
the same algorithm.
1.) Does anyone have some comparative ratings for the NR routine four1
and other routines in Pascal or C?
2.) Though this shows my naivety about the details of the FFT, Is there
any acceleration available for strictly integer data input versus
real input to the FFT routine? i.e. is there an optimization available
for integer data? I assume that regardless of input you will return
a real complex spectrum instead of an integer complex spectrum?
Thanks,
--
Bill Murphy murphy@newton.physics.purdue.edu
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!mentor.cc.purdue.edu!pur-ee!pur-phy!murphy From: murphy@pur-phy (William J. Murphy) Newsgroups: comp.dsp Subject: FFT for integer data Message-ID: <2620@pur-phy> Date: 4 Oct 89 16:18:32 GMT Reply-To: murphy@newton.physics.purdue.edu.UUCP (William J. Murphy) Organization: Purdue Univ. Physics Dept., W. Lafayette, IN Lines: 29