Consumer Electronics

DISC

In the Laser Vision System, Fig. 14.1 (a), which records video information, the signal is recorded on the disc in the form of a spiral track that consists of a succession of pits. The intervals between the pits are known as lands. The information is present in the track in analog form. Each transition from land to pit and vice versa marks a zero crossing of the modulated video signal. On the compact disc, Fig. 14.1 (b), the signal is recorded in a similar manner, but the information is present in the track in digital form. Each pit and each land represents a series of bits called channel bits. After each land/pit or pit/land transition there is a 1, and all the channel bits in between are 0, (see Fig. 14.2).

The density of the information ...