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From: jans@mako.UUCP (Jan Steinman)
Newsgroups: net.audio
Subject: Re: CD Reflections - 44.1k?
Message-ID: <525@mako.UUCP>
Date: Sun, 20-Jan-85 23:15:03 EST
Article-I.D.: mako.525
Posted: Sun Jan 20 23:15:03 1985
Date-Received: Wed, 23-Jan-85 07:25:31 EST
References: <15100001@hpfcmp.UUCP> <3411@mit-eddie.UUCP> <1420@hplabs.UUCP> <755@clyde.UUCP> <258@petrus.UUCP> <272@mtxinu.UUCP>
Reply-To: jans@mako.UUCP (Jan Steinman)
Organization: Tektronix, Wilsonville OR
Lines: 20

In article <272@mtxinu.UUCP> ed@mtxinu.UUCP (Ed Gould) writes:
>When I studied signal theory briefly about 12 years ago, there was a theorem
>stating that it was *impossible* to push more information through a signal
>than the bandwidth of the signal, e.g., one can't send more than k bits per
>second through a k Hz bandlimnited channel.

It must have been very brief study -- you're confusing signalling rate
(commonly known as "baud" rate) with the maximum frequency rate at which a
bandwidth limited channel will pass a sine wave.  Quadrature phase encoding
(the kind used in 1200 and up modems) isn't magic, and doesn't betray Nyquist,
it simply takes advantage of the relatively greater time-domain \binary/
bandwidth contained in the linear, but frequency-domain limited channel.

The relationships between bits-per-second and Hz is a very complex thing --
seldom a 1:1 relationship.  If the bandwidth is perfectly "square" with no
phase distortion, the number of bits you could pack to a Hz is limited by the
noise floor, not the frequency of the carrier.
-- 
:::::: Jan Steinman		Box 1000, MS 61-161	(w)503/685-2843 ::::::
:::::: tektronix!tekecs!jans	Wilsonville, OR 97070	(h)503/657-7703 ::::::