1. Analog signal is a continuous electromagnetic waves that may be propagated in a media depending on frequency.
2. For example : Copper wire media, such as Twisted pair and Coaxial cable, Fiber optic cable and atmosphere or space propagation ( wireless ).
3. Analog data can be represented by digital signals .
4. Analog data are encoded to occupy a different portion of spectrum .
1. Digital signal is a sequence of voltage pulses that may be transmitted over copper wire medium.
2. For example : A constant positive voltage level may represent binary 1 and a constant negative voltage level may represent binary 0 .
3. Digital data can be represented directly, in binary form, by two voltage levels.
4. Analog data are encoded using a codec to produce a digital bit stream.
Analog signal converted into Digital signal : Analog signal is converted into Digital signal by either of two methods:
PCM ( Pulse code Modulation )
Delta Modulation ( DM )
PCM is based on Sampling theorem whereas DM is binary behavior .