Listmembers, The original poster wrote: > I have a question on the use of a 3 meter fully anechoic chamber. > > Can this 3 meter chamber be used to qualify a product for FCC or CISPR > class A, since the required test distance is 10 meter?
I thought another clause in FCC Part 15 was important, too. Clause 15.31(d) says: (d) Field strength measurements shall be made, to the extent possible, on an open field site. Test sites other than open field sites may be employed if they are properly calibrated so that the measurement results correspond to what would be obtained from an open field site. <snip remainder of clause> Is it practical to get corresponding measurements in a 3m semi-anechoic chamber, let alone a fully-anechoic chamber? Pat Lawler EMC Engineer SL Power Electronics Corp. emc-p...@ieee.org wrote on 07/30/2008 02:51:01 PM: > Since were in the process of buying 5m chamber this thread caught my eye. > > I checked with the FCC, and they point to this paragraph in part 15.31: > > (f) To the extent practicable, the device under test shall be measured > at the distance specified in > the appropriate rule section. The distance specified corresponds to the > horizontal distance between the > measurement antenna and the closest point of the equipment under test, > support equipment or > interconnecting cables as determined by the boundary defined by an > imaginary straight line periphery > describing a simple geometric configuration enclosing the system > containing the equipment under test. > The equipment under test, support equipment and any interconnecting > cables shall be included within this > boundary. > (1) At frequencies at or above 30 MHz, measurements may be performed at > a distance > other than what is specified provided: measurements are not made in the > near field except where it can be > shown that near field measurements are appropriate due to the > characteristics of the device; and it can be > demonstrated that the signal levels needed to be measured at the > distance employed can be detected by the > measurement equipment. Measurements shall not be performed at a distance > greater than 30 meters > unless it can be further demonstrated that measurements at a distance of > 30 meters or less are impractical. > When performing measurements at a distance other than that specified, > the results shall be extrapolated > to the specified distance using an extrapolation factor of 20 dB/decade > (inverse linear-distance for field > strength measurements; inverse-linear-distance-squared for power density > measurements). > I would be very concerned if requirements were written that said only 10 > metre chambers or OATS were acceptable... > Best regards, > Derek Walton > L F Research > > Bill Stumpf wrote: > > Both answers are correct, but also the term Fully Anechoic Chamber > > raises a flag. The FCC does not allow the use of fully anechoic > > chambers for emissions testing (30MHz - 1000MHz). Reference ANSI > > C63.4(2003) Section 5. > > > > CISPR 22 does not allow the use of fully anechoic chambers (Section > > 10.4) & (CISPR 16.1.4) > > > > All test sites must meet vertical and horizontal theoretical Site > > Attenuation. > > > > Bill Stumpf > > ------------------------------------------------------------------------ > > *From:* emc-p...@ieee.org [mailto:emc-p...@ieee.org] *On Behalf Of > > *Pettit, Ghery > > *Sent:* Wednesday, July 30, 2008 2:06 PM > > *To:* Rudd, Adam; emcp...@aol.com; emc-p...@ieee.org > > *Subject:* RE: Class A antenna distance > > > > Note that the allowance for shorter measurement distances in CISPR 22 > > is for small devices, too. And, as noted, is limited to Class B > > devices. Plus, some regulators do not allow this option to be used > > and insist on 10 meter data. > > > > > > > > Ghery Pettit > > > > > > > > > > > > ------------------------------------------------------------------------ > > > > *From:* emc-p...@ieee.org [mailto:emc-p...@ieee.org] *On Behalf Of > > *Rudd, Adam > > *Sent:* Wednesday, July 30, 2008 11:59 AM > > *To:* emcp...@aol.com; emc-p...@ieee.org > > *Subject:* RE: Class A antenna distance > > > > > > > > 47CFR 15.31(f)(1) allows measurements at distances other than > > specified and details the extrapolation factor. > > > > http://edocket.access.gpo.gov/cfr_2007/octqtr/47cfr15.31.htm > > > > > > > > EN 55022 Section 10.2.1 has a note that specifically makes an > > allowance for Class B devices to be measured at 3m. I tend to think > > the detail of Class B being included and Class A being omitted from > > the note has significance. > > > > *Best Regards,* > > > > *Adam Rudd* > > Engineer (EMC) > > NCR Corporation, RHSS > > Duluth, GA > > (770) 495-2825 > > > > ------------------------------------------------------------------------ > > > > *From:* emc-p...@ieee.org [mailto:emc-p...@ieee.org] *On Behalf Of > > *emcp...@aol.com > > *Sent:* Wednesday, July 30, 2008 2:26 PM > > *To:* emc-p...@ieee.org > > *Subject:* (no subject) > > > > > > > > Dear members, > > > > > > > > I have a question on the use of a 3 meter fully anechoic chamber. > > > > > > > > Can this 3 meter chamber be used to qualify a product for FCC or CISPR > > class A, since the required test distance is 10 meter? > > > > > > > > Please provide any reference to paragraphs in the standards. Your > > responses are appreciated. > > > > > > > > Thanks, > > > > > > > > Timothy A. Pierce > > > > Tap Engineering, Inc. > > > > > > > > > > > > > > > > > > > > ------------------------------------------------------------------------ > > > > Get fantasy football with free live scoring. Sign up for FanHouse > > Fantasy Football today > > <http://www.fanhouse.com/fantasyaffair?ncid=aolspr00050000000020>. > > > > - ---------------------------------------------------------------- > > 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- > > ---------------------------------------------------------------- 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 > > > - > ---------------------------------------------------------------- > 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. 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