Difference between EMI and EMC?

All electronic devices emit electromagnetic waves while operating, if these emissions are excessive then they can impact other devices that are operating around it by causing interference. The measure of the level of emission of electromagnetic waves from a device is called EMC (Electromagnetic Compatibility) testing.

EMI (Electromagnetic Interference) testing is a test to check the amount of electromagnetic interference exists in an environment due to the emission of electromagnetic waves/signals from devices present in that environment or from other external factors. So it there is TV, Microwave, Phone and Computer in a room, each device emits some electromagnetic waves. The combination of these EM signals from all these devices in the room, is called Electromagnetic Interference.

There are two basic aspects to EMI/EMC testing: electromagnetic emissions produced by your product (EMI) and immunity to radiated or conducted electromagnetic radiation (EMC). You can use oscilloscopes, spectrum analyzers and test receivers to tackle EMI problems from different perspectives and angles. Each offers a different approach and diagnostic techniques that can certainly complement each other at different stages of the product development cycle.

To conduct EMC tests, you use a different set of equipment to generate the radiated and conducted emissions necessary to test your equipment. This gear can generate the waveforms specified in standards such as EN61000-4-3, EN61000-4-6, ISO 11452-2 and ISO 11452-4. The thing to keep in mind is that there are different standards for different types of equipment. The reason for this is that consumer electronics, automotive electronics, and airborne electronics all operate in different environments.