Phase modulation (PM) is a modulation pattern that encodes information as variations in the instantaneous phase of a carrier wave.
The phase of a carrier signal is modulated to follow the changing voltage level (amplitude) of modulation signal. The peak amplitude and frequency of the carrier signal remain constant, but as the amplitude of the information signal changes, the phase of the carrier changes correspondingly. The analysis and the final result (modulated signal) are similar to those of frequency modulation.
Phase modulation is widely used for transmitting radio waves and is an integral part of many digital transmission coding schemes that underlie a wide range of technologies like WiFi, GSM and satellite television.
Phase modulation is closely related to frequency modulation (FM); it is often used as an intermediate step to achieve FM. Mathematically both phase and frequency modulation can be considered a special case of quadrature amplitude modulation (QAM).
Phase modulation is used for signal and waveform generation in digital synthesizers, such as the Yamaha DX7 to implement FM synthesis. A related type of sound synthesis called phase distortion is used in the Casio CZ synthesizers. Wikipedia, Phase Modulation
See Also
Amplitude Modulation
Berry phase
Figure 8.10 - Each Phase of a Wave as Discrete Steps
Figure 8.11 - Four Fundamental Phases of a Wave
Figure 8.2 - Compression Wave Phase Illustration
Figure 9.10 - Phases of a Wave as series of Expansions and Contractions
Figure 9.14 - Wave Flow and Phase as function of Particle Rotation
Figure 9.5 - Phases of a Wave as series of Expansions and Contractions
Fourth Phase Of Water
Frequency Modulation
Modulation
phase
Phase Change
phase conjugation
Phase Velocity
Phaser
three phases of action
Three-phase electric power
9.26 - Orbital Phases