Electromagnetic interference, or EMI, is the interference that is caused by an electromagnetic disturbance that disrupts the transmission of a signal or the performance of a device. We all encounter EMI on a daily basis. This interference appears in a variety of forms, including:
* Noise heard over speakers due to a mobile phone communicating with a tower to process a call
* An electronic appliance generating undesirable noise over the radio
* Disturbances in audio or visual signals due to low-flying aircraft
However, this interference can be mitigated through EMI suppression.
Types of EMI
EMI exists in two types: radiated and conducted. Radiated EMI is caused by induction and conducted EMI is when there is physical contact between the source of the interference and the affected circuits. Conducted EMI can be suppressed by using EMI filters.
Suppression of Conducted EMI
EMI suppression filters are electronic passive devices that are used to suppress conducted EMI that is present on a power line or signal. The filters work by presenting a higher resistance to frequency content. Essentially, the low pass design of EMI filters impedes the flow of high frequency signals through the use of shunting capacitors and series inductors. This results in reduced unwanted signal strength, thereby minimizing the effects of unwanted signals on components and devices.
They can be used for a variety of applications, including:
* AC adaptors
* Secondary power lines for digital A/V equipment
* Data lines
* Energy management systems
* Automatic lighting
* AM radio equipment
* Implantable medical devices
* Military/space electronic modules
* Laboratory equipment
* Factory automated equipment
Requiring EMI Suppression
In daily life, EMI can be a source of annoyance and inconvenience. However, on a large scale, EMI can be a safety concern. For instance, in the aerospace industry, electromagnetic interference can pose large threats and is therefore monitored by international aviation authorities. Similarly, if electromagnetic interference causes performance issues in medical devices, the results could be catastrophic for patients. The same holds true for automated machinery in factories. Much of this equipment relies on specific programming and adheres to strict guidelines. Anything that interferes with its performance can result in a loss of money and potentially danger to the operators. Utilizing EMI suppression is necessary to avoid daily annoyances and to ensure the safety and operability of important industries.
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