Path: utzoo!attcan!uunet!nih-csl!lhc!adm!cmcl2!phri!roy
From: roy@phri.nyu.edu (Roy Smith)
Newsgroups: sci.electronics
Subject: Re: ..but what about _output_ filtering for D/A's?
Message-ID: <1990Oct26.034707.13720@phri.nyu.edu>
Date: 26 Oct 90 03:47:07 GMT
References: <1319@beguine.UUCP> <17660121@hpfcdj.HP.COM> <7486@eos.arc.nasa.gov> <88@sierra.STANFORD.EDU>
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Organization: Public Health Research Institute, New York City
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rosentha@sierra.STANFORD.EDU (rosentha) writes:
> Can a 20 and 21khz tone combine to give an audible difference frequency?
> Yes they can, if they are loud enough.  The ear has some nonlinearity and
> should mix the two signals down to a kiloherz.

	I missed the beginning of this, but rosentha's statement doesn't
make sense.  You don't need any nonlinearities to mix two signals to get
their sum and differences, all you need is a (linear) adder.  What you need
a nonlinearity for is to get detection without a mixer.
--
Roy Smith, Public Health Research Institute
455 First Avenue, New York, NY 10016
roy@alanine.phri.nyu.edu -OR- {att,cmcl2,rutgers,hombre}!phri!roy
"Arcane?  Did you say arcane?  It wouldn't be Unix if it wasn't arcane!"