Assessing the EMC-related risk of using commercial items (CI or COTS, as they are known) has long been a pet project of mine. So, I received a question lately that went something like this (paraphrasing the main points):
- I am aware the risk analysis or gap analysis is part of the process for analyzing the risk severity depending on test methods, level, frequency coverage etc.
- However, this is hard especially for laymen or those that are lesser-experienced to figure out whether is a low risk, medium or even high risk before comparing to the platform or mission criticality.
- How am I supposed to gauge the level of risk given some of the tests in terms of either commercially or military that I did not touch on before?
So, this person understands the crux of the commercial item EMC issue, that there is a “gap” between commercial EMC standards and military EMC requirements. And that gap represents a risk that the system will operate without interference in its electromagnetic environment. He also brings up another very important item: it takes some expertise to do such a risk analysis. I will add a conclusion that is reached after consideration of the three items, that it takes the entire system engineering team to “gauge the level of risk.” Maybe that’s the part that’s not so well understood, that it’s not all up to the EMC folks. The definition and acceptance of risk is largely out of their hands. The EMC engineers can help determine the likelihood and severity of potential EMI problems that may arise from the use of COTS items that are qualified to particular commercial EMC standards. But, that’s not an exercise for a beginner or the faint of heart! After that, it’s up to the systems engineering team to determine how big the risk is to fielding an effective system. That is, these are the guys that build the big “risk cube” of red, yellow and green squares and determine the overall risk “number,” hopefully in close coordination with the EMC engineers. And finally, it’s up to the program management team to accept the risks or approve the implementation of some kind of fix.
Bottom line: it’s a team effort! Unfortunately, a lot of time today, the EMC engineer is like the poor kid that’s picked last and stuck out in right field (bad youth baseball metaphor!). He’s out there to be kept out of the way. Likewise, there is a tendency among uneducated (unaware would be a kinder word) program managers that since a commercial item has passed some sort of commercial EMC standard that it is ready to deploy. Sadly, that’s not usually the case. And just like how that kid in right field sometimes can actually make a catch, sometimes the EMC engineer will catch a potentially dangerous EMI problem with a commercial item before a system is fielded.
-Brian Farmer
