- The
compact disc was
launched in 1982. The
first recording released
on CD was Billy Joel's
52nd Street. The
CD offered the home
consumer for the first
time, high quality
digital audio in a
robust and convenient
format. The main
attractions for the CD
was the ability to play
your favorite 'record'
more than just a few
times without leaving
scratches, noise or
damage as the CD was
very durable. The
consumer also enjoyed
instant access between
tracks, the remote
control facility and the
small size.
-
- The
disadvantages at the
launch was that few
titles were available
and the cost of the CD's
was much higher than
that of both vinyl
and cassette
tape. CD player
prices were also much
higher than turntables
and cassette decks back
in 1982. But the
catalogue of music
through the 1980s
quickly grew and player
costs quickly reduced.
By 1994 just 12 years
after launch, the CD
dominated the market in
music sales in the UK
and is still the
dominant format.
Technical
information:
- The
compact disc is read by
a laser which receives a
series of digital pulses
from a track of bumps
(125 nanometer high) as
it follows a spiral
track from the middle of
the disc outwards. The
track width is tiny at
just 0.5 microns wide,
with 1.6 microns
separating the tracks.
The data storage on a 74
minute CD is so vast
(650MB) that the spiral
track if it could be
unwrapped would be
almost 5 miles long. The
CD initially rotates in
the player at 500 rpm as
the laser reads the
inner tracks, the speed
slowly decreases to 200
rpm as the outer
tracks are read. This
keeps the data rate
constant as the laser
traverses the disc. The
digital sample rate is
44.1 kHz which is more
than twice that of the
highest audible
frequency ensuring high
resolution digital to
analogue conversion. There
is no contact between
the laser reader and the
disc during playback
ensuring no physical
wear of the disc. With
careful handling and
storage CDs will last
more than a lifetime.
James
T Russell invented the
optical audio system and
holds a total of 22 patents.
The CD was taken into
production by the giant
Philips and Sony
corporations in 1982.
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