Essential Guide to Computer Data Storage: From Floppy to DVD, The

Digital and Analog Signals

Analog versus Digital

Most signals in nature are analog and their characteristics vary continuously with time. The sounds we hear, the light we see, the temperature we sense, all of them represent a continuous signal—a data stream with a specific value at any given instance of time. The movements of the trees in the forest or the waves in the ocean are registered by our sensors as a continuous analog signal.

Human vision, hearing, and speech are analog too. When we speak, for example, we generate continuous sound waves that travel in the air by creating pressure fluctuations. When these waves are received by the listener's ear, they cause the eardrum to vibrate and send appropriate signals to the brain, similar to the ...