See phase coherence.

The imaginary part of the axial propagation constant for a particular mode, usually expressed in radians per unit length.

In the transmission of a single-frequency wave from one point to another, the delay of an arbitrary point in the wave that identifies its phase.
Note: Phase delay may be expressed in any convenient unit, such as seconds, degrees, radians, or wavelengths.

1. A phase deviation from a specified value.
2. An unintentional deviation from the nominal phase value.

A circuit or instrument that detects the difference in phase between corresponding points on two signals.

In phase modulation, the maximum difference between the instantaneous phase angle of the modulated wave and the phase angle of the unmodulated carrier.
Note: For a sinusoidal modulating wave, the phase deviation, expressed in radians, is equal to the modulation index.

A graphic representation of the phase relationships between two or more waveforms.
Note: A phase diagram may be represented as a vector diagram or as an amplitude-vs. -time diagram.

The time interval or phase angle by which one wave leads or lags another. Synonym phase offset.

Distortion that occurs when (a) the phase-frequency characteristic is not linear over the frequency range of interest, i.e., the phase shift introduced by a circuit or device is not directly proportional to frequency, or (b) the zero-frequency intercept of the phase-frequency characteristic is not 0 or an integral multiple of 2 radians. Synonym phase-frequency distortion.

See delay equalizer.