Date: Sat, 22 Jul 2000 20:18:37 -0700 (PDT) From: Kris Kennaway <kris@FreeBSD.org> To: "Jeroen C. van Gelderen" <jeroen@vangelderen.org> Cc: arch@freebsd.org Subject: Re: Quantifying entropy Message-ID: <Pine.BSF.4.21.0007222010590.52795-100000@freefall.freebsd.org> In-Reply-To: <397A5DC9.91DAAD8C@vangelderen.org>
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On Sat, 22 Jul 2000, Jeroen C. van Gelderen wrote:
> Could you make a couple of megabytes of you raw samples
> available? I don't have a soundcard at hand but I do
> have the FIPS-140 tests and a bunch of others.
Sure, they're at physics.usc.edu/~kennaway/soundnoise.bz2 (just over 10M
worth)
Some interesting numbers:
The shannon entropy of this sample as a pure probability distribution is
8.50 bits/sample (they're 16-bit signed values).
Compressing with gzip -9 and comparing the file sizes gives an entropy
estimate of 10.4 bits/sample.
Compressing with bzip2 -9 gives an estimate of 7.90 bits/sample,
suggesting there is indeed some time-correlation in the signal noise.
Kris
--
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-- Charles Forsythe <forsythe@alum.mit.edu>
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