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From: myers@hpfcdj.HP.COM (Bob Myers)
Newsgroups: sci.electronics
Subject: Re: ..but what about _output_ filtering for D/A's?
Message-ID: <17660123@hpfcdj.HP.COM>
Date: 22 Oct 90 18:50:46 GMT
References: <1319@beguine.UUCP>
Organization: Hewlett Packard -- Fort Collins, CO
Lines: 15

>As Bob has pointed out, the key here is nonlinearities.  Interestingly,
>the visual analog of this DOES work, i.e. the sum of two high frequency
>gratings (which cannot be resolved) can produce a visible beat.

Uh, Jeff, I'm still not certain I go along with this - isn't the above
phenomenon the result of interference (two items of slightly different
wavelengths - or in this case, spacing - resulting in constructive and
destructive addition of the signals at a much longer, and hence visible,
wavelength) rather than intermodulation (the actual multiplication of
sinusoids of different frequencies)?


Bob Myers  KC0EW   HP Graphics Tech. Div.|  Opinions expressed here are not
                   Ft. Collins, Colorado |  those of my employer or any other
myers@fc.hp.com                          |  sentient life-form on this planet.