Continuous phase modulation: Difference between revisions

Revision as of 09:42, 24 December 2005

Revision as of 09:47, 24 December 2005

Line 3:

continuous manner. For instance, with [[QPSK]] the carrier instantaneously jumps from a sine to a cosine (i.e. a 90 degree phase shift) whenever one of the two message bits of the current symbol differs from the two message bits of the previous symbol.

This discontinuity requires a relatively large percentage of the power to occur outside of the intended

band (e.g., high fractional out-of-band fractional power), leading to poor spectral efficiency.

Furthermore, CPM is typically implemented as a constant-envelope waveform, i.e. the transmitted carrier power is constant.

Therefore, CPM is attractive because the phase continuity yields high spectral efficiency, and the constant-envelope