EMC, or electromagnetic compatibility, refers to the ability of a device or system to operate in compliance with the requirements of its electromagnetic environment and not produce intolerable electromagnetic interference to any equipment in its environment. Therefore, EMC includes two aspects of the requirements: on the one hand, it refers to the equipment in the normal operation of the process of electromagnetic interference in the environment can not exceed a certain limit; on the other hand, it refers to the apparatus in the environment where the presence of electromagnetic interference has a certain degree of immunity, that is, electromagnetic sensitivity.