About Compact Disc Digital Audio - PROCEED PCD 3 User Manual

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About Compact Disc
Digital Audio...
To most people, a Compact Disc (CD) looks like a small, silver
phonograph record. In fact, there are some important differences
between records and CDs.
The information on a phonograph record is contained within its
grooves. This analog information is read by a stylus riding along in the
grooves and transmitted via a cartridge. The digital information on a
CD, though arranged in similar grooves, is read by a laser mechanism
(called a pickup ). A phonograph's stylus
must be in contact with the record,
but a CD player's pickup never
touches the CD. The information
on the CD is transmitted via
complex decoder circuitry.
The CD rotates
counterclockwise, and the laser
pickup reads the underside of the
CD (the side opposite the label)
beginning at the center and
travelling toward the outer edge. As
the pickup moves away from the
center, the speed of rotation gradually
decreases from 500 to 200 revolutions per minute.
Programs on CDs are organized into tracks , usually corresponding to
songs or movements. This allows the user to easily and precisely select
a part of a program with virtually no wear and tear on the CD. There
Lindsay's First Symphony
First Movement Second Movement
(Track 1) (Track 2)
Index Numbers from Track 2
01 02 03 04 05 06
selection and programming. A single track may have up to 99
indexes.
Direction the disc rotates
Third Movement
(Track 3)
94 95 96 97 98 99
Direction the laser
pickup travels
may be as many
as 99 tracks on a
CD.
On some CDs,
tracks are further
broken down into
indexes . These
"tracks within
tracks" allow even
more precise