Analog vs Digital Signal

• analog: raw, continuous signal directly written down onto some kind of channel which accepts a range of values
  • magnetic tape, with a range of magnetism to write down music
  • film, which is directly sensitive to light
  • phone, the sonic amplitude directly placed onto the phone wire
• digital: storing whichever signal into bits; using only 0/1 bits to represent the entire signal

Analog Communication

• message to be communicated is one of a continuum of possibilities
• can never fully remove the effect of noise which the communication channel gives

Digital Communication

• message to be communicated is one of a finite set of choices (0/1)
• can remove the noise induced by the communication channel by rebinarizing (“on-off keying”)—i.e. small fluctuations between voltages of transmission will not influence on/off measurement