Hi Prahlad,

This will likely seem a very trivial thing, and frankly I wouldn't rate this as being of the utmost importance either. Nonetheless, I find that there is often some confusion around the vernacular of matters concerning EMC. So, in the spirit of friendly and effective communication (a matter that in fact can be very important in such an international forum as this) I offer the following.

In your post you refer to "EMI and EM compatibility." In point of fact EMI is a subset of EMC. To test for EMC is, by definition, to test for EMI.

EMC (ElectroMagnetic Compatibility). EMC is often mistakenly thought of as Electromagnetic Compliance. I personally see no real harm in this confusion, but there is a significant distinction that warrants understanding. Compliance deals with bureaucratic regulations. Compatibility deals with the physics of "getting along and playing well with others."

EMC consists of two subsets. They are:

EMI (Electromagnetic Interference), the electromagnetic radiation a circuit generates,

and

EMS (Electromagnetic Susceptibility), the resilience of a circuit to function properly in the presence of electromagnetic radiation.

(Sometimes, if one is careless around high voltages EMS can better stand for Emergency Medical Services, but I'll leave that to Raghunathan to discuss. ;) )

In older publications you might see these topics referred to as RFC, RFI, and RFS respectively (Radio Frequency). Mostly you will run into the term RFI since this was in the days before the topic was expanded to include matters of susceptibility. In the earlier days people were only concerned that your circuit didn't bother anyone elses and it was your problem to make sure that your circuit worked under all conditions.

Anyway, this was just a tidbit that I thought might fit nicely into this discussion.