Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!ukma!tut.cis.ohio-state.edu!rutgers!att!ihlpl!knudsen
From: knudsen@ihlpl.ATT.COM (Knudsen)
Newsgroups: sci.electronics
Subject: Re: Audio Spectrum Analyzer chips wanted
Summary: FFT not too slow
Message-ID: <10391@ihlpl.ATT.COM>
Date: 3 May 89 23:11:51 GMT
References: <7958@killer.Dallas.TX.US>
Distribution: usa
Organization: AT&T Bell Laboratories - Naperville, Illinois
Lines: 22

In article <7958@killer.Dallas.TX.US>, ltf@killer.Dallas.TX.US (Lance Franklin) writes:
> The application, by the way, is a computer-displayed voiceprint...Fourier
> Analysis is just too slow.

Too slow on what?  Have you considered one of the DSP microprocessor
chips made by TI, AT&T, and various branches of JapanInc?
These are not all that expensive or hard to connect to RAM, ROM,
and A/D chips.  I forget the published FFT times for such beasties,
but you should have no trouble getting 10-50 FFTs per second.

Since you need to monitor all frequency bands at once, the FFT
really is the right way to go.  Analog circuits just don't time-mux
worth a damn.

You might consider hacking up a cheap stereo equalizer with a built-in
spectrum display.  My RadShack unit uses 10 discrete op-amp
filters to estimate each octave, but the freq resolution isn't
as good as you want.
-- 
Mike Knudsen  Bell Labs(AT&T)   att!ihlpl!knudsen
Round and round the while() loop goes;
"Whether it stops," Turing says, "no one knows!"