It depends on whether the SA displays the peak or the RMS amplitude of the spectral components. I think it's the RMS level, so you'd need to factor that into the calculation.
It's been my experience that you only need to measure the first 6 or 8 of the largest components to get number very close (<2%) to that of the RMS meter. Ralph McDiarmid, AScT Compliance Engineering Group Xantrex Technology Inc From: [email protected] [mailto:[email protected]] On Behalf Of John Woodgate Sent: Wednesday, April 25, 2007 2:48 PM To: [email protected] Subject: Re: MIL HBK 704-8 distortion factor In message <[email protected]>, dated Wed, 25 Apr 2007, Derek Walton <[email protected]> writes: >The ripple voltage... is this measured with an RMS meter, OR, is it the >root sum of the squares of the components as measured by a spectrum >analyzer? Shouldn't they theoretically be the same? In practice, you may need to measure a large number of very small components in order to get a result that is reasonably close to the r.m.s. meter result. Vice versa, make sure your r.m.s meter has enough bandwidth to include all significant components. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk There are benefits from being irrational - just ask the square root of 2. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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/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] 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/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] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
