CDPlayerJEW

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How a CD Player Works

A CD player reads a dicrete set of data off a CD. In short, a CD player takes this data and sends it through a digitla to analog converter, then through a low pass filter, and finally is output through speakers. A simple diagram illustrates this below.


Simple Block Diagram of Signal Pathway


When an audio CD is recorded, the music has an infinite amount of data points and can be represented as a continuous function of time . Because a medium, such as a CD, has a finite amount of space, it will not be able to hold since it has an infinite amount of data. Instead, the music is sampled at intervals to create a discrete function of time where is an integer and is the interval between samples.

This discrete signal can be represented mathematically by:

Then, the discrete signal is convolved by the D/A converter with a function :


This convolution, which is the convolution of the discretized signal and , a pulse function, will yield a graph that is no longer discrete, but is stepped. The following is an example:

Convolved Graph

In the frequency domain, the above stepped signal will look like the following:

Convolution (Time Domain) and it's frequency domain counterpart


- Principle author of this page: Jeffrey Wonoprabowo

- Image of CD Player Diagram and Convolution by Aric Goe or Todd Caswell (not sure which since both of them had it on their pages)