In message <c6cc56d1.50927%[email protected]>, dated Tue, 8 Sep 2009, Ken Javor <[email protected]> writes:
>Since dBs are logs of ratios, you cannot do sums of squares on them, >and take square roots. You would have to convert to numerics, do the >rss, and then convert back to dBs. CISPR 16-4-2 does indeed (or certainly appears to: it's not very well written) add dB values as the square root of the sum of squares. As you say, adding dB values (NOT squared) and square-rooting is equivalent to calculating the geometric mean value. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Things can always get better. But that's not the only option. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
