Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!unmvax!charon!hydra.unm.edu!ee5391aa
From: ee5391aa@hydra.unm.edu (Duke McMullan n5gax)
Newsgroups: sci.electronics
Subject: Re: Audio Spectrum Analyzer chips wanted
Summary: NOT SO
Keywords: Audio DSP, Fourier analysis, cet ettera
Message-ID: <5010@charon.unm.edu>
Date: 3 May 89 04:42:55 GMT
References: <7958@killer.Dallas.TX.US>
Sender: root@charon.unm.edu
Reply-To: ee5391aa@hydra.unm.edu.UUCP (Duke McMullan n5gax)
Organization: University of New Mexico, Albuquerque, NM
Lines: 35

>I am interested in any information on chips that would facilitate construction
>of an audio-range spectrum analyzer.  The ideal solution would be a single
>chip that could be accessed n-times a second and provide a computer a word or
>words in which each bit represents a frequency range, and the "on" condition
>would represent the signal at that range going above a preset threshold during
>the time-slice involved....however, any chip or set of chips that could do
>the same for a single frequency range would probably do.
>
>The application, by the way, is a computer-displayed voiceprint...Fourier
>Analysis is just too slow.

Discrete Fourier analysis is NOT too slow for most audio work; you're just
using the wrong hardware. Even a 33 MHz '386 with numeric coprocessor and
fast cache memory is probably too slow, but a DSP chip optimized for FFT
calculations isn't. There are PC plug in cards available with the DSP IC,
cache memory, support software, etc. on the market TODAY. They ain't cheap.

You probably want one of the type that does floating point calculations: the
fixed point variety is a nuisance to use, since you have to worry about 
scaling problems.

On this same note, if you haven't yet picked up a copy of the June "Radio-
Electronics," go out & get one. Now. Don't even finish reading this article.

Don Lancaster's "Hardware Hacker" column discusses three new ICs from 
Crystal Semiconductor in Texas which are fast, high resolution, CHEAP A/D
converters quite sutable for audio work. You probably need to know....


					Best o' luck,
						d


     "To be or not to be -- that is the square root of 4 B^2." -- Anon.
   Duke McMullan n5gax nss13429r phon505-255-4642 ee5391aa@hydra.unm.edu