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From: ed@mtxinu.COM (Ed Gould)
Newsgroups: rec.audio.high-end
Subject: Re: Improving
Message-ID: <10379@uwm.edu>
Date: 20 Mar 91 13:48:34 GMT
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> If you listen to a 20th generation copy of an analog signal, you'd
> probly find that, among other things, it is a lot noiser than the
> original, so surely the data on a 20th generation digital signal
> will contain much more noise than the original.

Only if it's copied as if it were analog data.  Correct copying of
digital information should regenerate and reform the signal at
every stage.  After all, the beauty of digital information is that
one can *know* what it's supposed to be.  If the copied digital
signal is not as good as the original, then there's something wrong
with the copy.

There is a separate question of error correction.  Errors do happen
in digital recording and transmission, but there are techniques
(involving redundant information) to correct such errors.  Some of
those techniques have an overhead of just a few percent, so they're
not a significant factor in storage space or transmission time.
Does anyone know what - if any - error correction techniques are
employed in digital audio?

Note that it is *extremely* unlikely for errors to appear within
logic circuits.  For all practical purposes, they only happen in
recording/playback and transmission.

-- 
Ed Gould                    mt Xinu, 2560 Ninth St., Berkeley, CA  94710  USA
ed@mtxinu.COM		    +1 415 644 0146

"I'll fight them as a woman, not a lady.  I'll fight them as an engineer."