| jetking |
05-14-2009 02:44 PM |
CD Changer
A compact disc, also popularly known simply as a CD, is an optical storage medium with digital data recorded on its surface. A compact disc player is a device that reads the recorded data by means of an optical beam and accurately the original information (music, pictures, or data). Because the player reads the information by optical means, there is no physical wear and tear on the disc. The basic technology used in all compact disc players is essentially the same, whether the player is designed for audio, video, or computer applications. This article will focus on players designed for audio (specifically, home audio) applications.
The history of the compact disc system can be traced back to the early 1970s, when rapid advancement in digital electronics, laser optics, and large scale integration (LSI) technologies took place. Many companies started exploring the possibility of storing audio signals in optical form using digital rather than analog means. A practical method of modulating the audio signals was found using theories published in 1948 by a scientist named Claude E. Shannon. This method, known as Pulse Code Modulation (PCM), samples audio signals during a short time interval and then converts the samples into numerical values for storage in digital format.
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