I am very concerned about your step 4.....in terms of measurement time. Our software selects peaks automatically and 400 frequencies approaching the limit is not uncommon !!!!! Especially equipment with DC brush collector motors create numerous spikes high above the limits (even when compliant!).
A verification peak pass on all of those peaks only with 1-10 seconds dwell time gives us an indication if dwell time is too short. If the verification measurement is higher then the initial measurement, then dwell time definitely was too short. The conclusion is drawn automatically by the software. That method still does not cope with fully missed peaks, just those that are varying slowly. And even then, we use 0-6 dB of margin only, because by design, a QP cannot be higher than a peak measurement. Regards, Ing. Gert Gremmen ce-test, qualified testing bv Van: emc-p...@ieee.org [mailto:emc-p...@ieee.org] Namens kbalasubraman...@scmmicro.co.in Verzonden: Thursday, December 04, 2008 4:55 PM Aan: Amund Westin CC: emc-p...@ieee.org Onderwerp: Re: Radiated emission - time at each frequency The lab where we regularly test follow the below sequence. 1. Run the peak scan with 10 milli seconds dwelling at each step. 2. Repeat this for 3 or 4 times, because in every run generally some new frequencies are getting added to the list. 3. Rotate the turn table in steps of 30 deg. angle and in every angle repeat step 1 & 2. 4. Manually list all the frequencies where the emission peak is near to the limit line (say about 10 dB margin). 5. Measure the QP for each of this frequency by varying the angle and height of antenna. It takes about 5 to 7 minutes for each frequency and we can very clearly see that the QP level is varying drastically. Sometimes I noticed about 15 dB change. Record the maximum value measured. 6. Repeat steps 1 through 6 for the other polarisation. Still I see variation in the results between the testing on any 2 days for the same piece of device with same support equipment. And testing the same set up in another lab puzzled me many times. Frequencies appearing in one lab will not be seen in the other, level will differ more than 10 dB at same frequency between the labs, both the labs are accredited. Sincerely                                                          SCM Microsystems (India) Pvt. Ltd. K. Balasubramanian                                         Modules 0506, 0507 & 0508, D – Block, Manager – Hardware                                        South Wing, TIDEL Park, Tel : +91 44 42931391                                      #4, Rajiv Gandhi Road,(formerly Canal Bank Road) Fax :+91 44 22540029                                       Taramani, Chennai – 600113. India E-mail:kbalasubraman...@scmmicro.co.in         Web : http://scmmicro.com ‘This email and any attachment may contain confidential information and are intended solely for the use of the named recipient(s). If you have received this information in error, you are prohibited from reading, copying, distributing and using the information. If you are not a named addressee or otherwise an intended recipient you are requested to immediately notify the sender and to delete this email and all attachments from your system.’ |------------> | From: | |------------> >----------------------------------------------------------------------------------------------------------------------------------------| |"Amund Westin" <am...@westin-emission.no> | >----------------------------------------------------------------------------------------------------------------------------------------| |------------> | To: | |------------> >----------------------------------------------------------------------------------------------------------------------------------------| |<emc-p...@ieee.org> | >----------------------------------------------------------------------------------------------------------------------------------------| |------------> | Date: | |------------> >----------------------------------------------------------------------------------------------------------------------------------------| |12/04/2008 04:26 PM | >----------------------------------------------------------------------------------------------------------------------------------------| |------------> | Subject: | |------------> >----------------------------------------------------------------------------------------------------------------------------------------| |Radiated emission - time at each frequency | >----------------------------------------------------------------------------------------------------------------------------------------| When doing Radiated emission 30-1000 MHz according to EN55022, for hold long time do you measure at each frequency (band)? Best regards Amund - 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 <, emc-p...@ieee.org> 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 <emcp...@ptcnh.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org> David Heald <dhe...@gmail.com> - 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 <emc-p...@ieee.org> 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 <emcp...@ptcnh.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com> - 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 <emc-p...@ieee.org> 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 <emcp...@ptcnh.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
