Electromagnetic interference

Recording of US House of Representatives debate on October 8, 2002, interrupted and distorted by electromagnetic interference from a solar flare at approximately 2:30 p.m.

Electromagnetic interference (EMI), also called radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction.^[1] The disturbance may degrade the performance of the circuit or even stop it from functioning. In the case of a data path, these effects can range from an increase in error rate to a total loss of the data.^[2] Both human-made and natural sources generate changing electrical currents and voltages that can cause EMI: ignition systems, cellular network of mobile phones, lightning, solar flares, and auroras (northern/southern lights). EMI frequently affects AM radios. It can also affect mobile phones, FM radios, and televisions, as well as observations for radio astronomy and atmospheric science.

EMI can be used intentionally for radio jamming, as in electronic warfare.

EMI sound sample 1

A GSM mobile phone signal interferes with a speaker system.

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EMI sound sample 2

A Wi-Fi signal interferes with a speaker system.

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^ Based on the "interference" entry of The Concise Oxford English Dictionary, 11th edition, online
^ Sue, M.K. (15 June 1981). Radio frequency interference at the geostationary orbit. NASA Technical Reports Server (Report). Jet Propulsion Laboratory. hdl:2060/19810018807.

[1] Based on the "interference" entry of The Concise Oxford English Dictionary, 11th edition, online

[2] Sue, M.K. (15 June 1981). Radio frequency interference at the geostationary orbit. NASA Technical Reports Server (Report). Jet Propulsion Laboratory. hdl:2060/19810018807.

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