CISPR 22 has a note that allows 3 meter testing for small class B devices. It does not apply to class A devices, nor large class B devices. That said, there is nothing going on to change this in CISPR 22. Part of the reason we're not working on it is that multiple limits at test distances of 3, 5 and 10 meters are being proposed for CISPR 32, the new multimedia equipment emissions standard. The test distances being proposed in CISPR 32 are dependent on the maximum dimension of the EUT. This work is being done in CISPR SC I WG2. Keep in mind that my estimate for the earliest this standard could be published is 2010.
Ghery S. Pettit From: [email protected] [mailto:[email protected]] On Behalf Of John Woodgate Sent: Thursday, July 31, 2008 12:59 PM To: [email protected] Subject: Re: Class A antenna distance In message <[email protected]>, dated Thu, 31 Jul 2008, Grace Lin <[email protected]> writes: >What is the possibility to have CISPR accept 3m measurement distance, I don't know. Maybe Ghery could comment? > unconditionally, for Class B devices? I feel 3m is more realistic in >the residential environment. I agree. >I argue with (friendly) BSMI (Taiwan's authority). The BSMI regulator >tells me if CISPR accepts 3m unconditionally, BSMI will follow. > >The current version of CISPR 22 accepts 3m distance only under the >condition as Ghery pointed out. Indeed, and it may be that the reason is that the 3 m measured values are often MORE than 10 dB above the 10 m values, so that it would be more difficult to pass at 3m if the limits were simply set at 10 dB above the 10 m limits. I would be pragmatic and set the 3 m limits at about 12 dB above the 10 m limits. But that is heresy and would not be accepted. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Either we are causing global warming, in which case we may be able to stop it, or natural variation is causing it, and we probably can't stop it. You choose! 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 [email protected] 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] 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/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
