Alex, You are on the right track. However, even a VBW of 9 kHz will not yield a true average measurement in this frequency range. First of all, it is not likely that the spectrum analyzer meets CISPR requirements as a test receiver. Second, using video averaging as a substitute for an actual average detector requires a VBW that is significantly less than the RBW, and the amplitude scale must be linear instead of log (the average of the log is different than the average). This is a highlight of the most important settings - CISPR 16 will have the detailed requirements from which suitable and/or reasonable instrument settings can be determined. It is not surprising to hear of these differences - the receiver measurement definitely takes precedence over the spectrum analyzer. Thanks, Mike
From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf Of Alex McNeil Sent: Thursday, December 16, 2004 8:19 AM To: emc-p...@ieee.org Subject: Conducted Emissions PK/AVG Hi Guys, I had a product tested that failed the conducted emissions. The switch mode power supply was the problem. It runs at approx. 200KHz. The failed readings were in the 150KHz to 600KHz band. The peaks were over the Avg and below the QPk, so the Avg test was done. This resulted in the failures. However, after close examination of the Test lab results, the printout showed IF BW 9KHz AND AVG BW 30KHz below the graphical and tabulated results. The tests were done on a SA. I have a receiver here and my test results for PK are the same as the Test Lab but for the Avg my test results are significantly lower than the Test House. Is the problem that the Test House may have used “AVG BW 30KHz” and this should have been “AVG BW 9KHz” the problem or am I missing something here? Thank you for your time, it is always appreciated. Kind Regards ALEX ________________________________________________________________________ This email has been scanned for all known viruses and appropriate content by the Messagelabs mail service. ---------------------------------------------------------------- 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 emc-p...@ieee.org 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 emcp...@ptcnh.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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 emc-p...@ieee.org 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 emcp...@ptcnh.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc