EECS20N: Signals and Systems


  • Functions are mappings on sets.
  • Signals are functions that represent information.
  • Audio signals are mappings from time to air pressure.
  • Audio signals represent sounds perceived by humans.
  • An image is a mapping from a region of space to light intensity.
  • Images carry information perceived through human vision.
  • A radio signal is a mapping from time to electromagnetic waves.
  • Radio signals carry information of all types, but must be converted to be perceivable by humans.
  • An event trace is a mapping from indexes to events.
  • Event traces carry information about discrete actions.
We first consider signals whose domains represent time and space.