interference

Interference (specifically, wave interference) is oscillations resulting from the interaction of two or more waves of some type (e.g., sound waves, light waves, ocean waves) that are passing through the same region of their medium. Given known wave patterns, this interference can be predicted (generating known interference patterns) and conversely, the resulting pattern can be analyzed, which is the basis for interferometers, used with electromagnetic radiation such as radio and visible light. Constructive interference occurs where wave peaks cross each other, producing a larger oscillation at that point, and destructive interference is that in which peaks sit on top of valleys, canceling each other out, and the oscillation is reduced or absent. When waves are crossing each other at an angle, these kinds of interference appear alternately, producing a characteristic striped pattern: this, given the redirection of light through diffraction is what forms the concentric stripes of Airy disks.

The results of interference are useful in analysis of the waves and their source(s). Such interference can also be carried out between pairs of oscillating electronic signals such as those recording physical waves. Over some frequency regimes (specifically radio), converting waves to such signals and interfering them can be more practical for analysis than interfering the actual physical waves. Such interference can be carried out on either an analog signal or (through calculation) on a digitization of the signal.

The term interference also refers to unwanted contamination, such as radio frequency interference (RFI). This can be due to the above mechanism, but often is some signal overpowering or confusing the one of interest.