1. An undesired audible disturbance in the audio frequency range.
2. Any undesired acoustic wave or signal, or undesired component of a desired acoustic signal, whether or not audible to the human ear; e.g., interference accompanying a sonar echo.

A longitudinal wave that (a) consists of a sequence of pressure pulses or elastic displacements of the material, whether gas, liquid, or solid, in which the wave propagates, (b) in gases, consists of a sequence of compressions (dense gas) and rarefactions (less dense gas) that travel through the gas, (c) in liquids, consists of a sequence of combined elastic deformation… (Read More →)

The branch of science and technology that is devoted to the production, transmission, control, processing, transformation, reception, and effects of sound, longitudinal waves, particularly as vibration, pressure, or elastic waves and shock phenomena in material media. [After Weik '96]

A variation of the refractive index of a material caused by interaction with acoustic energy in the form of a wave or pulse.
Note: The acousto-optic effect is used in devices that modulate or deflect light.

The discipline devoted to the interactions between acoustic waves and light waves in a material medium. [After 2196]
Note: Acoustic waves can be made to modulate, deflect, and/or focus light waves by causing a variation in the refractive index of the medium.

1. In satellite communications, the process of locking tracking equipment on a signal from a communications satellite.
2. The process of achieving synchronization.
3. In servo systems, the process of entering the boundary conditions that will allow the loop to capture the signal and achieve lock-on.

See ATOW.

1. In a communications system, the time interval required to attain synchronism.
2. In satellite control communications, the time interval required for locking trackingequipment on a signal from a communications satellite.

1. Alternate Carrier Routing.
2. Automatic Carrier Routing

Automatic Configuration Server