Skip to content


Modulation is the process of embedding a message signal, for example a digital bit stream or an analog audio signal, inside another signal that can be physically transmitted.

Analog modulation#

  • Amplitude modulation (AM)
  • Frequency modulation (FM)
  • Phase modulation (PM)

Digital modulation#

In digital modulation, an analog carrier signal is modulated by a discrete digital signal.

  • Phase-Shift Keying (PSK): a finite number of phases are used.
  • Frequency-Shift Keying (FSK): a finite number of frequencies are used.
  • Amplitude-Shift Keying (ASK): a finite number of amplitudes are used.
  • Quadrature Amplitude Modulation (QAM):