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Commonly used terms in the Electrical industry.
electromagnetic interference (EMI)
(1) any electromagnetic disturbance that interrupts, obstructs, or otherwise degrades or limits the effective performance of electronics/electrical equipment. It can be induced intentionally, as in some forms of electronic warfare, or unintentionally, as a result of a spurious emissions and responses, intermodulation products, and the like. Additionally, EMI may be caused by atmospheric phenomena, such as lightning and precipitation static and non-telecommunication equipment, such as vehicles and industry machinery.
(2) unwanted high-frequency electrical signals, also known as radio frequency interference (RFI), which can be generated by
power electronic circuits switching at high frequencies. The signals can be transmitted by conduction along cables (450 kHz to 30 MHz) or by radiation (30 MHz to 40 GHz) and can interfere with control or other electronic equipment.
electromagnetic interference filter
a filter used to reduce or eliminate the electromagnetic interference (EMI) generated by the harmonic current injected back onto the input power bus by switching circuits. The harmonic current is caused by the switch action that generates switch frequency ripple, voltage and current spikes, and high-frequency ringing. Generally called an EMI filter.
interference
(1) a process in which two waves interact. Interference occurs when the complex properties of the wave are combined instead of simply their two amplitudes. The wave interference can be constructive when they both have the same phase, or destructive when they have opposite phases.
(2) a disturbance on a communication system caused by the presence of a signal, or small number of signals, of man made origin. The interference may be due to the presence of signals external (other systems) or internal (e.g., multiple access interference) to the system of interest. Compare with background noise.
(3) an interaction whereby a process that is supposed to be independent (and isolated) from another process does indeed perform some action that has an effect visible from the second process. Interference can be caused by direct writing to the state of the second process or by indirect effects, such as by monopolizing the use of a system module.
(4) any external electrical or electromagnetic disturbance which causes an undesired response or degradation of the desired signal.
(5) the mutual influence of two waves or vibrations of any kind, producing certain characteristic distorting phenomena, is
known as interference. For example, radio-frequency interference (RFI) or crosstalk and intersymbol interference (ISI) caused by interference between successive pulses in an optical fiber.
interference cancellation
a signal processing technique where an interfering signal is estimated, regenerated based on the estimate, and then canceled from the received signal, leaving a potential interference-free, desired signal. Examples are multiple access interference cancellation, co-channel interference cancellation, echo cancellation.
interference channel
a multiple transmitter, multiple receiver communications system in which each received signal is a (possibly non-deterministic) function of two or more transmitted signals. See also broadcast channel, multiple access channel.