1) Analog to Digital conversion

-It is an electronic process in which a continuously variable (analog) signal is changed,
without altering its essential content, into a multi-level (digital) signal.

-The input to an analog-to-digital converter (ADC) consists of a voltage that varies
among a theoretically infinite number of values.

-Examples are sine waves, the wave forms representing human speech, and the signals
from a conventional television camera.

-The output of the ADC, in contrast, has defined levels or states.

-The number of states is almost always a power of two – that is, 2, 4, 8, 16, etc.

2) Digital to Analog Conversion

-In this conversion technique, the amplitude of analog carrier signal is modified to
reflect binary data.

-A Digital to Analog Converter, or DAC, is an electronic device that converts a
digital code to an analog signal such as a voltage, current, or electric charge.

-Signals can easily be stored and transmitted in digital form; a DAC is used for the
signal to be recognized by human senses or non-digital systems.