Chileshe, Chris wrote: > Group, > > On several occasions during radiated immunity EMC testing, I have > observed products deviate > or even fail and subsequent manual spot checks at the frequencies of > interest have revealed no > anomalous behaviour. > > I saw such behaviour on a product I was testing recently, and spent a > long time conducting spot > checks at the frequency and the immediate neighbourhood without much > success replicating > the failure. I tried turning the modulation on and off and even > applying the modulated field instantly > on and off without much success. I did a sweep again and the deviation > was back like clockwork! > > What is the explanation for this and there are techniques for getting > round this 'problem'? > > Rgds > > - Chris
If the scanning is digitally controlled, the RF signal generator may exhibit a switching transient as the internal PLL is switched and the ALC locks on. This transient may exceed the settled level. Usually not a problem, but if the magnitude of the transient is unusually large, or the equipment under test is marginal in its susceptibility, it can be pushed over the edge. -- Isidor Straus Chief Scientist, Curtis-Straus, LLC A Bureau Veritas Company 978-486-8880, Fax 978-486-8828 [email protected] 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
