TABLE OF CONTENTS All electrical and electronic devices generate electromagnetic interference, and are susceptible to it. It is your job as product designer to reduce this generation and susceptibility to acceptable levels. With the increasing penetration of solid-state electronics into all areas of activity, acceptable levels of interference have become progressively tighter as physical separation between devices has reduced and reliance on their operation has increased. Solid-state, particularly integrated circuit technology, is more susceptible than the vacuum-tube devices of years ago, and the popularity of plastic cases with their lack of screening is a further factor. The ability of a device to operate within the limits of interference immunity and suppression is known as electromagnetic compatibility (EMC).
In some areas of electronics EMC has been a product requirement for a long time. Military electronics has severe limitations imposed on it, often because of the proximity of high-power pulse equipment (radars) to sensitive signal processing equipment in the same aircraft, ship or vehicle, and military EMC standards first appeared in the 1960s. The increasing use of walkie-talkies on process plant and elsewhere has prompted users of safety-critical instrumentation to specify a minimum immunity from RF interference. Measuring and weighing equipment must be prevented from giving incorrect readings in the presence of interference, and domestic broadcast receivers should be able to work alongside home computers.
Radio frequencies are not the only source of interference. Transients can be generated by power switching circuits, lightning, electric motors, spark ignition devices or electrostatic...
