Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!linus!philabs!micomvax!micomz!softech
From: softech@micomz.UUCP
Newsgroups: net.audio
Subject: CD in cars and other MYTHS !
Message-ID: <163@micomz.UUCP>
Date: Tue, 7-Jun-83 23:35:06 EDT
Article-I.D.: micomz.163
Posted: Tue Jun  7 23:35:06 1983
Date-Received: Wed, 8-Jun-83 19:10:44 EDT
References: hou5e.494
Lines: 24


	I was reading all the debate about CD players in cars, and it occured
to me that we all forgot one VERY important thing: Playing a CD in a moving
vehicle would be about as difficult as playing a standard record (with stylus
and all). The tracking system in CD players is so precise and so fragile that
it would be impossible to design one small enough and strong enough to resist
the G-forces involved without losing the necessary precision. Remember that
the little laser beam must be kept ON TRACK and IN FOCUS at all times. Now we
are talking about tracks that are only 1/20 th of a normal record groove in
width, and there is no mechanical contact to do the tracking with! Its all
done optically by a complex servo mechanism that analyses the shape of the
laser on the record surface. Minute fluctuations due to hole centering errors
or warpage of the surface are corrected by ultra-fast voice-coils that hold
the focusing apparatus (remember the little devil SPINS!). A small bump on
the road would easily cause several seconds of "errors", if not complete
jumping of tracks.

	So, for all of you waiting to trade-in your old Delco...

	(By the way, the same goes for the Walkies fans, unless you go real
	easy on your roller skates...)

Richard "Ears" Blouin.
!philabs!micomvax!micomz!softech