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From: jeh@ritcv.UUCP (Jim Heliotis)
Newsgroups: net.video,net.analog
Subject: Re: How does Beta HiFi audio avoid head switching transients
Message-ID: <1596@ritcv.UUCP>
Date: Mon, 18-Mar-85 16:27:00 EST
Article-I.D.: ritcv.1596
Posted: Mon Mar 18 16:27:00 1985
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Organization: Rochester Institute of Technology, Rochester, NY
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Xref: watmath net.video:1069 net.analog:207

> I heard a rumor that the HiFi audio signals are actually recorded
> digitally.  If this is true, it is easy to see ways where head
> switching would not be a problem.  However, I don't really know
> if these signals are digital or not.  Does anyone else?  If they're
> not, then how do they achieve any better sound than conventional
> audio recorders? (or do they?)

They are not digital.  You are probably confusing it with pulse-coded
modulation methods which use the entire video tape to record a digital
(audio-only) signal.

Better sound is acheived because information is written in diagonal
swipes across the tape, so the head-to-tape speed (H) is much higher than
the tape-through-machine speed (M).

                     / ^ head direction on tape
                    /
                   /
                  /
                 /
                /
               /
              /
             /  a
            ______________________ > tape direction

H = M / (cos a)

				Jim Heliotis
				{allegra,seismo}!rochester!ritcv!jeh
				rocksvax!ritcv!jeh
				ritcv!jeh@Rochester

P.S. I feel this is adequate since signal quality ultimately depends on the
number of magnetic particles the head sees per unit of time.  Other factors
determine how close to this ideal one can come.