From: deanaj@elec.canterbury.ac.nz (A. J. Dean)
Newsgroups: rec.audio.high-end
Subject: Re: Why digitize: some bunk...
Date: 05 Nov 1992 03:18:18 +0000 (GMT)
Organization: Electrical Engineering, University of Canterbury, New Zealand
 <01GQSRKORWWG8ZGO4N@csc.canterbury.ac.nz>; Thu, 5 Nov 1992 16:18:26 +1300
 5 Nov 92 16:18:22 NZD
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Originator: tjk@csd4.csd.uwm.edu

Steven Abrams (abrams@cs.columbia.edu) wrote:
: In article <1d5v47INNbfl@uwm.edu> Richard d Pierce <DPierce@world.std.com> writes:
: > Further,all recording and reproducing techniques are analog in the
: > strictest sense of the term. There are discrete analogs and there are
: > continuous analogs. Both analogs are, at best, poor representations of
: > musical reality. On some recordings, I am willing to tolerate the errors
: > in a discrete-analog representation, in others, I am willing to tolerate
: > the errors in continuous-analog representations. 
: >
: > Let's please use our termiology correctly, eh?
In that case, a linearly quantised PCM recording is analog, while an FM
stereo transmission is not! I used it in a report and got flamed a bit...

: traditionally labeled "analog" do not decrease the reslution of the
: discrete signal on purpose, whereas so-called "digital" technologies
: do.  
I presume you're talking about quantising here. In my understanding, a
properly dithered quantising process does not lose much resolution at all
(at LF anyway). It's only adding noise, which happens in 'analog' processes
as well. Since the dither is not itself quantised (well, forgetting about
Heisenberg...) you can represent any level you want exactly in theory, just
like you can with an 'analogue' process, in theory. My little argument falls
apart for real signals of duration less than infinity though, so ignore it!

: I guess your reason for calling digital a "discrete-analog"
: representation is because the stored numbers are analogous to the
: original wave form.  Isn't that stretching it?  I always looked at
:...
: you even have a set of numbers -- not very analogous to air pressure
: variations.  

Consider a 16 bit bus conveying a 44.1 kHZ sampled 16 bit digital audio
signal to say a dac. The information is certainly digital, but the binary
value on the bus at each sampling period is (as far as possible) directly
analogous to the air pressure level at (say) each mic (well, you get what I
mean) and the samples arrive when they are supposed to (ie analogous to
time). It seems to me this digital _representation_ is a much better
analogue than something recorded or transmitted with eq, compression,
modulation, etc. Low level effects (eg loss or resolution, noise,
nonlinearity) may occur in either system. The 'intuitively' analog nature of
linearly quantised PCM is why it holds a special place in my heart...
[insert favourite soppy stuff here]. Again, my little argument (ARGUMENT_2)
falls apart because PCM is almost always a digital analog of an 'analog'
analog, and thus suffers the drawbacks of both systems. Wonder what happened
to Sony's early ideas of digital microphones and speakers? 

Antony (deanaj@elec.canterbury.ac.nz) who cannot resist making postings like
this and getting into trouble once again...