Dan, Looks like the detectors are not correct. The measurement should be done with a QP detector, the limit line shown is the old FCC Class B. If the measurement is to the new limits, then measurement should start at 0.15 MHz. No conclusion can be made for the region from 0.15 MHz-0.45 MHz! All we can see is that the device did not fail the limits for the average detector between 0.45 MHz - 30 MHz under the new FCC Class B (I dare say partially "harmonized") standard.
The peak values did go above the average limits of the new standard (between 1-3 MHz and 6-7MHz) but this is meaningless unless you know something about the nature or characteristics of the emission. Judging from the difference between the result from the average and peak detector all we can say is that we are dealing with some form of broadband or even perhaps partially intermitent emission. This is impossible to tell unless one have some knowledge of the product. :-) Looks like this is a case of mistaken identity of sorts. :-) Just my 2 ยข worth. Tim Foo EMC Short Course Singapore 25 Nov 2002 http://www.cec.np.edu.sg/courses.phtml?course_code=XC45 "Pettit, Ghery" <[email protected] To: "'Dan Pierce'" <[email protected]>, [email protected] m> cc: (bcc: Wan Juang Foo/ece/staff/npnet) Sent by: Subject: RE: Conducted Line Emissions owner-emc-pstc@majordo mo.ieee.org 11/08/02 06:56 AM Please respond to "Pettit, Ghery" Dan, >From the data provided one cannot make a pass/fail decision. The (old) FCC limits for power line conducted emissions are based on a quasi-peak detector. Going over the limit with a peak detector does not necessarily mean that the product fails as a peak detector quite often will read higher than a quasi-peak detector. Meeting the limit with an average detector is meaningless as it is not the specified detector. The new limits are equal to the limits in CISPR 22 and require both an average and a quasi-peak detector reading. In either case, this data is incomplete. The lab cannot tell you that you fail, nor can it say you pass. Radiated emissions are specified with a quasi-peak detector for frequencies up to and including 1 GHz and an average detector above 1 GHz. Ghery Pettit Intel -----Original Message----- From: Dan Pierce [mailto:[email protected]] Sent: Thursday, November 07, 2002 1:05 PM To: [email protected] Subject: Conducted Line Emissions Greetings: I am looking for proof that I can use the averaged value for emissions rather than the peak value. Attached is a chart that I was given by an Asia test site that told me I failed. According to my past experience, I believe that the average power is what I should be concerned about. Similar to radiated emissions right? Thank you. Daniel J. Pierce Sr. Design Engineer OpenGlobe, Inc. > (An Escient Technologies Affiliate) 6325 Digital Way Indianapolis, IN 46278 mailto:[email protected] P: (317) 616.6587 F: (317) 616.6587 ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
