What is EMC?
EMC - or Electromagnetic Compatibility to give it its full title - is the ability of an electronic device to work as intended within its environment. This means that the device needs to limit its own noise so that it doesn’t cause interference to other electronic devices. As well as this, the device needs to be able to deal with electromagnetic energy being radiated from other devices without any loss in performance. This is called EMC Immunity. There are numerous EMC standards which specify the allowable noise and required immunity levels.
EMC can be a complex subject to understand. Levels of noise vary over a wide range, as well as the parameters which affect these levels. To add to this, electromagnetic emissions occur as both radiated and conducted noise. The noise can travel as either conducted noise, radiated noise or a mixture of both.
EMC has always been an issue throughout the history of electronics. In the early days, most interference was due to radio frequency and hence EMC was originally called “RFI.” As time went on it became apparent that interference can occur at any frequency so the term “EMI” started to replace RFI. The source of electromagnetic energy was referred to as the “culprit” and the circuit being affected was the “victim”
It was later discovered that the source of electromagnetic energy could come from an electronic device, like a transmitter. Any circuit which is affected may have to be redesigned so that it can operate effectively in the presence of electromagnetic energy. Some sources and circuits could even be parts of the same device or system, thus giving rise to the notion that there is no actual culprit or victim. All electronics have to be able to function reliably in their environment without loss of performance. They must also restrict their own emissions so that they don’t cause interference to other electronics in their vicinity. This is EMC.