ELL: Fwd: Re: arsclist how to archive your language and other matte
xernaut at YAHOO.COM
Fri Oct 20 07:54:51 UTC 2000
> Dear Brian,
> All digital media have some form of error-correction, it is built
> into the "standard." It is one stage up from "error detection", in
> which you know a fault has occured, but you cannot correct it. (The
> ISBN Book Numbering system, for example, has error detection which
> will sound an alarm if one digit is changed or two transposed, so you
> know you've typed something incorrectly; but you don't know *what* has
> gone wrong). MS-DOS, Compact Disc, R-DAT, etc. have error-*correction*
> built into them to match the kind of errors one might reasonably
> encounter (large ones at nearly the same place for CD, much shorter
> ones affecting consecutive tracks for R-DAT, etc.) Error *correction*
> is built into the medium and automatically invoked whenever you
> reproduce something.
> But to know *how* something is degrading, one needs to get at the
> digits *before* error correction. Our CD Tester does this. Audio CDs
> have two "layers" or error correction (CD-ROMs have three), and our
> tester lists *all* the errors, where they are, and whether they cross
> the threshold into audibility. By repeatedly putting the CD into the
> tester every year (or whatever), and printing-out the results, one can
> get a picture of how fast it is degrading, and clone the data when it
> is approacing audibility.
> Because we haven't much money, ours is a cheap CD Tester, a Model
> CDA2000 CD Analyser made by CD Associates, Inc., 15A Marconi, Irvine,
> California 92618. email: <www.cdassociates.com>. We clone our R-DATs
> onto CD-R as soon as we get them home to minimise the risks; I expect
> R-DAT (and PCM-701) tape testers exist, but we don't use them.
> The difficulty is that one doesn't get any understanding of *why*
> something is failing. A much more expensive *analogue* tester is
> needed, which measures the *quantities* of things like reflectivity,
> edge-sharpness, carrier-to-noise ratio, etc. These are *analogue*
> measurements, and equipment which can do these is at least five times
> the price; I'm afraid I have no experience of it.
> Peter Copeland
>______________________________ Reply Separator
>Subject: Re: arsclist how to archive your language and other matters
>Author: Brian Levy <xernaut at yahoo.com> at Internet
>Date: 16/10/2000 10:36 AM
>One more thing:
>such digital error correction and monitoring, how expensive and from where
>would one get such equipment?
>Why pay for something you could get for free?
>NetZero provides FREE Internet Access and Email
Kiwat Hasinay Foundation:
Preserving Caddo Heritage
211 W. Colorado Ave.
Anadarko, OK 73005 USA
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