I read in !emc-pstc that francesco.campede...@transport.alstom.com wrote (in <of3e02755c.a4628162-onc1256d6c.002b4...@transport.alstom.com>) about 'Additivity of Conducted Emission' on Wed, 23 Jul 2003:
>If I measure the >emission for one driver, would it be possible to derive the emission >level when two or more drivers are present (at least a worst case)? If >yes, how to do it? Does the noise add up linearly (so that I have to add >6 dB for two driver, 20 dB for ten in the worst case - the noise from >each driver has the same frequency and phase) ? Yes, the worst case is probably arithmetic addition. 'Probably', because there might be some subtle effect that gives a better or worse result. But the *expected* situation is probably root-sum-square addition, i.e. 10 dB for ten units. Of course, if these units are self-contained and marketed as individual items of commerce, with each being CE marked, there is no requirement to add up the emissions for regulatory purposes. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
