Mr. Richmond makes an excellent point. A well-designed EMI control process would levy some kind of derivative CE limit on the peripheral device that operates off a PC's secondary supplies, and it would levy some kind of secondary-to-primary isolation requirement on any FCC/CE stamped power supply, the convolution of the isolation requirement and the dc CE limit yielding primary mains-conducted rfi below the appropriate FCC/CISPR limit. In today's exploding peripherals market, such an approach would make a lot of sense.
This approach would also allow the peripheral test sample to operate off a clean source of dc power, eliminating the need to hunt for peripheral noise sources amongst the PC's emanations. > From: Cortland Richmond <[email protected]> > Date: Fri, 7 Oct 2005 19:54:34 -0400 > To: ieee pstc list <[email protected]> > Subject: RE: Conducted emission testing for FCC & CE. > > Neil Barker posted: > >>> You need to select your host PC very carefully to ensure that it is > compliant, and that it is quiet enough for you to be able to tell whether > or > not your device is contributing to the emissions. << > > > One also needs to take care the host selected doesn't suppress an emission > another would promote. > > > Cortland Richmond > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list. Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to [email protected] > > Instructions: http://listserv.ieee.org/listserv/request/user-guide.html > > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > > Scott Douglas [email protected] > Mike Cantwell [email protected] > > For policy questions, send mail to: > > Jim Bacher: [email protected] > David Heald: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc > - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
