What is EMI?
EMI, can be defined as electromagnetic energy which affects operation of an electronic device. EMI sources sometimes may be created by environmental events such as natural storms and solar radiation. However, EMI source is mostly another electronic device or electrical system. Although EMI can be created by any electronic device, it is possible that some equipment and components such as mobile phone, welding machine, engine and LED screen, may create more disturbance than the others. As operation of electronics in isolation is rare, products are generally designed to function in the presence of a fair amount of EMI. Besides military class and avionics equipment, this is especially important for devices which require high reliability in all cases.
What is EMC?
EMC, is a measure for the capability of a device to operate as planned in a shared operation area, and at the same time it also does not affect operation of the other equipment in the same environment as designed. It can be defined as evaluation of how a device would react when it is exposed to electromagnetic energy, immunity (or sensitivity) test. On the other hand, measurement of EMI electromagnetic area created by internal electric systems of the device is defined as emissions test.
EMI / EMC TESTS
MIL-STD-461 E/F/G
MIL-STD-461E/F/G military standard; The response of the device is controlled by measuring the emissions of the electronic device and the antenna path and by applying electromagnetic interference to the device via external transmission and antenna.
MIL-STD-1275 D/E
MIL-STD-1275E, DEPARTMENT OF DEFENSE INTERFACE STANDARD: CHARACTERISTICS OF 28 VOLT DC ELECTRICAL SYSTEMS IN MILITARY VEHICLES., This standard covers the limits of transient voltage characteristics and steady state limits of the 28 volt (V) direct current (dc) electric power circuits of military vehicles.
RTCA DO-160G
To standardize the production and testing of these sensitive components, the(RTCA) publishes DO-160, Environmental Conditions and Test Procedures for Airborne Equipment — a set of best practices which has been adopted by all major aerospace and avionics manufacturers.