coherency
- Coherent refers to radio, light or infrared radiation in which waves of the same frequency oscillate in one and the same plane.
- In data processing, coherence is said to exist when the current data sets with which the various processors are working are in perfect agreement. In multiprocessor systems, this is achieved by special consistency programs.
- In sound radiation, two sound waves are coherent when the same signals with the same phase and amplitude are radiated by two loudspeakers. This coherence causes the signals to overlap at a certain distance from the speakers and their levels add up. If the distance is at most one third of the wavelength, this results in a level gain of 6 decibels( dB) and a doubling of the sound power by 3 dB. With three loudspeakers, the level gain is 10 decibels. With incoherent signals, i.e. signals that do not have a defined phase relationship, the signals are not completely added, but can also subtract, depending on the phase relationships.