NO!!!! The 120 dB safety margin comment and point number 7 are self-consistent but consistently WRONG!
If you screw up "I Love Lucy" reception, regardless of your subjective assessment of the nuisance value that represents, you are in violation of not only the philosophy of FCC emissions control, but also the verbiage attached to the FCC sticker that says regardless of measured compliance, if it causes interference, fix it or turn it off. I reiterate, the fact that your product could be out not 30 - 40% but 30 - 40 dB has no safety impact to a non-antenna connected receiver. But if it interferes with either I Love Lucy, or a cell phone calling in 911, you are violating the spirit and letter of the law. ---------- >From: Chris Maxwell <chris.maxw...@nettest.com> >To: "'emc-p...@majordomo.ieee.org'" <emc-p...@majordomo.ieee.org> >Subject: RE: FCC + FCC = FCC? - Outlaw >Date: Fri, Jun 22, 2001, 12:15 PM > > > Hi all, > > This thread has been interesting. However it has taken a somewhat > philisophical turn. I'd like to "distill" it a little bit. In short, FCC > + FCC does equal FCC in certain circumstances just like CE + CE = CE in > certain circumstances. > > You need to ask yourself: (honestly and sincerley without the influence of > mind altering substances) > > Self, > > 1. Do I manufacture all of the pieces of this system? > 2. Are all of the pieces of this system already FCC approved? > 3. Is the FCC approval appropriate for my intended environment (i.e needs > Class B for residential)? > 4. Am I satisfying the test assumptions for the pieces that are already FCC > approved? (i.e am I using shielded cables where required, am I following the > grounding recommendations?) > 5. Am I using the pieces of this system in their intended environments? > 6. Do I have design control over the pieces of the system? (i.e did you or > your company layout the circuitboards, choose the components ...) > 7. Will my system be used in situations in which interference could > comprimise public or personal safety? (as opposed to simply screwing up the > neighbor's reception of "I Love Lucy".) > 8. Have I spent a couple of years in compliance engineering? Do I feel > comfortable making these decisions? Have I reviewed the test data? > > If you can answer: > 1. No (A "yes" hurts only slightly) > 2. Yes > 3. Yes > 4. Yes > 5. Yes > 6. No (A "yes" hurts only slightly) > 7. No (This one MUST be "No") > 8. Yes, Yes, Yes > > Then you can be 95% certain that FCC+FCC = FCC. > Only 95%!!!!!! Oh no! > Hold on, before you write that $5,000 check for EMC testing, remember that > most EMC tests themselves have double digit percentage errors. > > One warning. If you are going to make a "Large Number" of IDENTICAL > systems, and you plan to make "alot" of money off of them; or if you have > any gut feeling that someone could get hurt; do the test anyway. It's just > good sense. > (I'll let you decide what "Large Number" and "alot" mean :-) > > You can use the same reasoning for CE + CE = CE (from an EMC perspective) > > Yes, yes I know that there are some that will say that every system must be > tested, even if you build it in your basement. But the reality is that EMC > measurements are a "fuzzy" realm. Tests are fuzzy approximations of real > world conditions. Some of the tests have error margins of 30-40%. The > emissions and immunity standards have a built in 120dB "safety margin" to > account for this (or you could argue that the "safety margin" was > accidentally put there because the emissions standards were designed to > protect antenna coupled receivers). Either way, it is there. It doesn't > mean that we can be cavalier with EMC; but we can use good judgement to save > time, money and hassles. The same time and money that can be better spent > mitigating real EMC and safety problems. All of these rationales are behind > why both the EMC directive and the FCC rules give some leeway with the > Declaration of Conformity process. > > With many "fuzzy" logic questions the best piece of test equipment that you > can use is a trained neural network. An experienced brain is a prime > example. > > Why not call a vertically- > applied manulo-pedally-operated quasi-planar chernozem-penetrating and > excavating implement a SPADE? > > BECAUSE SOMETIMES IT'S A SHOVEL!!!! > > My opinions only. > > Chris > > > > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Michael Garretson: pstc_ad...@garretson.org > Dave Heald davehe...@mediaone.net > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > All emc-pstc postings are archived and searchable on the web at: > http://www.rcic.com/ click on "Virtual Conference Hall," > ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: pstc_ad...@garretson.org Dave Heald davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
