Assuming that a conducted emission test still will be levied, that requires the kind of derivative limit and isolation requirement I suggested below. Plus, you are now dependent on how clean the power supply is, instead of using a laboratory grade power supply.
> From: "Sterner, David [S&FS]" <[email protected]> > Date: Mon, 10 Oct 2005 08:06:02 -0400 > To: "Ken Javor" <[email protected]>, "ieee pstc list" > <[email protected]> > Subject: RE: Conducted emission testing for FCC & CE. > > Why not test with the USB device connected to a USB hub and regard the > PC as AUX EQUIPMENT. > > Honeywell > David W. Sterner > Quality Assurance Engineering > Security & Custom Electronics > 165 Eileen Way > P.O. Box 9035 > Syosset, NY 11791 > Phone: (516) 921-6704 x6970 > Fax # (516) 364-6953 > [email protected] > <http://www.honeywell.com> > > > -----Original Message----- > From: [email protected] [mailto:[email protected]]On Behalf Of Ken Javor > Sent: Friday, October 07, 2005 9:47 PM > To: ieee pstc list > Subject: Re: Conducted emission testing for FCC & CE. > > > 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 > - 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
