What is EMI and RFI?
EMI stands for Electromagnetic Interference. It refers to the phenomenum where electromagnetic radiation interferes with the operation of an electronic or electrical device or system.
RFI (Radio Frequency Interference) is a subset of EMI, where the electromagnetic radiation in question is confined to the radio wave portion of the electromagnetic spectrum. EMI tends to be a shorter range phenomena, often occurring when the distance between circuits of devices is less than one wavelength, whereas RFI tends to be a longer range phenomena.
EMI and RFI are created by nearly every electronic device, and the operation of nearly every electronic circuit can be negatively affected by external sources of EMI/RFI. RFI is everywhere in today’s environment with radio communication devices filling the atmosphere with radio signals. Solar activity is also a very large generator of RFI and there are many sources outside of our solar system and galaxy that create significant radio signals, not the least of which is the cosmic background radiation left over from the big bang.
EMI / RFI together refer to the phenomena where electronic and electrical devices and wires both create and are affected by electromagnetic waves.