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What exactly is electromagnetic interference (EMI)? How does it affect our electronic devices?
In today's era of booming electronic technology, electromagnetic interference (EMI) has become an issue that cannot be ignored. Whether it is home electronic equipment, automotive electronic systems, or advanced communication equipment, electromagnetic interference may affect its performance and stability. Therefore, it has become crucial to understand what EMI is and its impact.
Electromagnetic interference refers to the performance degradation of electronic equipment or transmission channels caused by electromagnetic disturbances.
Electromagnetic compatibility (EMC) refers to the ability of electronic equipment to operate properly in the electromagnetic environment in which it is located without causing unnecessary electromagnetic interference. The main goal of EMC is to ensure that different devices operating in the same environment do not interfere with each other. To achieve this goal, three main aspects need to be considered: the generation of interference, the resistance of the equipment, and the propagation path of the interference.
The earliest electromagnetic interference problems can be traced back to lightning strikes. In the mid-18th century, lightning-induced electromagnetic pulses (LEMPs) enabled ships and buildings to be protected. With the popularization of electricity, since the end of the 19th century, more equipment has been affected by short-circuit faults in the power supply system, and various types of protection devices have emerged, such as circuit breakers and fuses.
After entering the 20th century, with the development of radio communications, problems that can cause interference have emerged in an endless stream. International regulations began to be established to ensure that radio communications were not interfered with. Design changes, such as the use of switchgear, have led to the emergence of electromagnetic interference in public and domestic equipment, and laws have been enacted to limit the sources of such interference.
Electromagnetic emissions are electromagnetic energy generated by some source, whether intentional or accidental, and released into the environment.
After World War II, the defense sector paid more and more attention to the effects of nuclear electromagnetic pulse (NEMP) and lightning strikes on equipment. Faced with increasingly stringent spectrum management, standards for various output levels are constantly being developed, which has led to the rise of the EMC industry, focusing on analysis, testing and design while ensuring equipment compliance.
It is critical to understand the nature of EMI and its effects on electronic equipment. EMI falls into several categories, including background noise and transient disturbances. The source can be artificial or natural. Man-made noise, such as from smart devices and home appliances, can affect other devices around them. Then there is the issue of the connection path—how EMI is transmitted from its source to the receiving device.
The purpose of EMC is to control EMI to prevent unwanted effects.
There are various measures to control EMI and improve compatibility, such as grounding, shielding, filtering and other design techniques. Good design can both reduce electronic emissions and enhance resistance to interference. To do this, designers need to know the principles of various electromagnetic interferences and their importance to the safety of electronic computers and household appliances.
With the advancement of technology, different countries and international organizations have gradually established a series of EMC standards, such as the International Electrotechnical Commission (IEC) and the Federal Communications Commission (FCC) of the United States. These standards help countries and companies regulate the design and production of equipment to avoid unnecessary interference with equipment operation.
In terms of testing, it is usually divided into emission and immunity testing, and the EMC compliance of the equipment is confirmed by professionally calibrated test equipment. Open Area Test Facilities (OATS) and EMC test rooms are common locations for this type of testing.
In summary, with the rapid advancement of electronic technology, the impact of EMI cannot be underestimated. Effective EMC management will help improve the performance and stability of electronic equipment and protect our lives and work from electronic interference. Are the challenges and solutions here worthy of further in-depth discussion?
