Dave et al, I'd suggest consideration of one other factor - ambient temperature.
One experience I had, an EUT was failing emissions during OATS measurements. After placing it in the conditioned OATS control room to warm up, it was then returned to the turntable where it then produced a passing result with margin. Until it chilled again. I believe many labs record temperature during measurements for their reports. It might be worth a look. Eric Lifsey At 3:13 PM -0700 3/24/05, [email protected] wrote: >I was thinking about the recent US/Taiwan EMC issue discussed here >and I thought I would apply "Inference to the best explanation" to >it. There was much conjecture about what is going on but we still >have no more than the original evidence. > >Inference to the Best Explanation: > >Evidence: > >E1: The device passed at the US lab >E2: The observed signal frequencies, at the US lab, correspond to >known clock frequencies >E3: The device failed at the Taiwanese lab >E4: The observed signal frequencies, at the Taiwanese lab, do not >correspond to known clock frequencies (they are different) >E5: The device passes at the Taiwanese lab when a ferrite is placed >on the USB cable >E6: The identical device was tested at both labs > >Hypotheses (rank ordered by me from best to worst): > >T0: The US lab is correct and the Taiwanese lab is in error >T1: The Taiwanese lab is correct and the US lab is in error >T2: The device has changed between the US lab and the Taiwanese lab >T3: Both labs are in error > >How one ranks the hypotheses depends on how they rate the evidence. > > Dave Cuthbert > Micron Technology > >---------------------------------------------------------------- >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/listserv/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: > >Richard Nute: [email protected] Jim Bacher: [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/listserv/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: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
