This is one of those cases where a single (or perhaps multiple) test(s) is/are worth a thousand expert opinions. One parameter which would be necessary to work out ahead of the measurement is what is the separation from walls that contain power lines (i.e., source of rectification harmonics), and separation from devices that operate at these frequencies, such as monitor pixel scanning rates.
Another practical problem is the size of the sensor. Magnetic sensors range from the handheld to the 60 cm diameter loop mentioned earlier, and different size loops will give different effective field intensities at the same separation from a near field source. Ken Javor Phone: (256) 650-5261 > From: John Woodgate <[email protected]> > Date: Fri, 6 Jul 2012 21:49:56 +0100 > To: <[email protected]> > Subject: Re: FCC maximum frequency measurement > > In message <cc1cc3a4.26adc%[email protected]>, dated Fri, 6 > Jul 2012, Ken Javor <[email protected]> writes: > >> Not quoting chapter and verse of any standard here, but if one were >> serious about controlling RE at these frequencies, the best approach >> would be controlling common mode conducted emissions on cables attached >> to the device, both power and signal. >> >> The limit would be based on the field intensity that would result from >> such conducted emissions at a separation which is deemed proper for >> typical use. In this manner, all the variables that would befuddle the >> test engineer are subsumed in a limit which is based on the maximum >> field intensity from a radiating cable; a simple problem susceptible to >> a closed form solution. >> > Indeed: that's what IEC/CISPR standards do, in most cases. One exception > is fluorescent lamps, which are clearly large enough to produce current > loop and thus significant magnetic fields. > -- > OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk > Instead of saying that the government is doing too little, too late or too > much, too early, say they've got is exactly right, thus throwing them into > total confusion. > John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. To post a message to the list, send your e-mail to > <[email protected]> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used > formats), large files, etc. > > Website: http://www.ieee-pses.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 <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher: <[email protected]> > David Heald: <[email protected]> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
