1. In general, extraneous energy, from natural or man-made sources, that impedes the reception of desired signals.
2. A
coherent emission having a relatively narrow spectral content,
e.g., a
radio emission from another transmitter at approximately the same
frequency, or having a
harmonic frequency approximately the same as, another emission of interest to a given recipient, and which impedes reception of the desired
signal by the intended recipient.
Note: In the context of this definition, interference is distinguished from
noise in that the latter is an
incoherent emission from a natural source
(e.g., lightning) or a man-made source, of a
character unlike that of the desired signal (
e.g., commutator noise from rotating machinery) and which usually has a broad spectral content.
3. The effect of unwanted energy due to one or a combination of emissions,
radiation, or inductions upon reception in a
radiocommunication system, manifested by any performance
degradation, misinterpretation, or loss of
information which could be extracted in the absence of such unwanted energy. [
NTIA] [
RR] (
188 )
4. The interaction of two or more
coherent or partially coherent waves, which interaction produces a resultant wave that differs from the original waves in
phase, amplitude, or both.
Note: Interference may be constructive or destructive,
i.e., it may result in increased amplitude or decreased amplitude, respectively. Two waves equal in
frequency and amplitude, and out of phase by 180°, will completely cancel one another. In phase, they create a resultant wave having twice the amplitude of either interfering
beam. (
188 )