EMC and EMI explained

Electromagnetic compatibility

From Wikipedia, the free encyclopedia

Anechoic RF chamber used for EMC testing (radiated emissions and immunity)

Electromagnetic compatibility (EMC) is the branch of electrical sciences which studies the unintentional generation, propagation and reception of electromagnetic energy with reference to the unwanted effects (Electromagnetic interference, or EMI) that such energy may induce. The goal of EMC is the correct operation, in the same electromagnetic environment, of different equipment which use electromagnetic phenomena, and the avoidance of any interference effects.

In order to achieve this, EMC pursues two different kinds of issues. Emission issues are related to the unwanted generation of electromagnetic energy by some source, and to the countermeasures which should be taken in order to reduce such generation and to avoid the escape of any remaining energies into the external environment. Susceptibility or immunityissues, in contrast, refer to the correct operation of electrical equipment, referred to as thevictim, in the presence of unplanned electromagnetic disturbances.

Interference, or noise, mitigation and hence electromagnetic compatibility is achieved primarily by addressing both emission and susceptibility issues, i.e., quieting the sources of interference and hardening the potential victims. The coupling path between source and victim may also be separately addressed to increase its attenuation.

Contents [hide] 1 Types of interference 1.1 Continuous interference 1.2 Pulse or transient interference 2 Coupling Mechanisms 2.1 Conductive coupling 2.1.1 Conduction modes 2.2 Inductive coupling 2.2.1 Capacitive coupling 2.2.2 Magnetic coupling 2.3 Radiative coupling 3 EMC control 3.1 Characterising the threat 3.2 Laws and regulators 3.2.1 Regulatory and standards bodies 3.2.2 Laws 3.3 EMC design 3.3.1 Grounding and shielding 3.3.2 Other general measures 3.3.3 Emissions suppression 3.3.4 Susceptibility hardening 3.4 EMC testing 3.4.1 Susceptibility testing 3.4.2 Emissions testing 4 History 5 EMC test equipment manufacturers (alphabetic) 6 See also 7 References 8 External links 8.1 Web sites 8.2 Specific topics

EMI

Electromagnetic interference

From Wikipedia, the free encyclopedia

"RIV" redirects here. For other uses, see RIV (disambiguation).

Electromagnetic interference in analog TV signal

Electromagnetic interference (or EMI, also called radio frequency interference orRFI) is a disturbance that affects an electrical circuit due to either electromagnetic conduction or electromagnetic radiation emitted from an external source. ^[1] The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit. The source may be any object, artificial or natural, that carries rapidly changing electrical currents, such as an electrical circuit, the Sun or theNorthern Lights.

EMI can be intentionally used for radio jamming, as in some forms of electronic warfare, or can occur unintentionally, as a result of spurious emissions for example through intermodulation products, and the like. It frequently affects the reception of AM radio in urban areas. It can also affect cell phone, FM radio and television reception, although to a lesser extent. If EMI for electronics or astronomy is reduced so is happened to RFI. (EMI/RFI in Roumanian language, 2005 - 2009).

Sound

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EMI sound sample. A Wi-Fi signal interferes with a speaker system.

Contents [hide] 1 EMI/RFI types 2 Susceptibilities of different radio technologies 3 Interference to consumer devices 4 History 5 Standards 6 EMI in integrated circuits 6.1 RF Immunity and testing 7 See also 8 References 9 External links

EMC/ EMI TESTING