continuous phase modulation (CPM)

Continuous PhaseModulation(CPM) is a phase modulation in which the phase changes continuously.

Unlike other phase modulations such as phase shift keying( PSK), the phase position in CPM modulation does not jump back to zero degrees phase position, or switch between a sine function and a cosine function as in quadrature phase shift keying( QPSK).

Continuous CPM modulation has better spectral efficiency because phase hopping requires a large amount of energy outside the transmission band. In addition, CPM modulation operates at a constant signal level, which means that the transmitted power remains constant.