John, In my experience... For part 15, the FCC rules always make reference to the AC Mains connection. There is no reference in rules to making measurments of DC conducted Emissions that I am aware of. This stands in contrast to the EU standards that do in fact indicate conducted limits on DC power, as well as many signal/communications cables.
For FCC, under the new DOC rules, FCC + FCC = FCC, if you test with a representative configuration, the device is declared compliant in all configurations. In practice this isn't likely to be 100% effective, however it would seem excessive to make a USB device comply with AC Mains limits on its DC power cable when the computer is known to have very good filtering in the 150k-30MHz range. The same can't be said for devices such as USB Hubs, where a simple class 2 supply is powering the USB device with limited if any filtering. Clif Clifton Brick Compliance, Safety and Patent Engineer Invisible Technologies, Inc. 1000 Fuller Drive Garrett, IN 46738 Phone 260-467-5139 Fax 260-467-5103 From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of John Woodgate Sent: Monday, April 10, 2006 12:45 PM To: emc-p...@ieee.org Subject: Re: Fw: FCC equipment authorization: Have RFID devices operating @ 13.56 MHz been exempted from conducted emission testing? In message <003001c65cb8$0eb3a570$4001a8c0@CompaqPresarioD>, dated Mon, 10 Apr 2006, Dward ATCB <dw...@atcb.com> writes >Your understanding is not correct. A USB device plugged into any other >device that is directly connected to the AC mains will need an oine >conducted testing. Several examples are: A USB dongle that gets its >power from the USB port and is plugged into a laptop where the laptop >gets its power from the AC mains will require conducted emissions. 'Conducted emissions' on WHICH CABLE? The mains cable of the power supply or the DC cable from the power supply to the load equipment? Or both? -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk 2006 is YMMVI- Your mileage may vary immensely. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 emc-p...@ieee.org Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com 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 emc-p...@ieee.org Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
