Michael, When I discussed synchronization I should have been clearer. I do not mean that the active edge of the modulation signal should occur at the zero crossing of the RF signal. I was discussing synchronization at a more basic level. Suppose the modulation signal is turned on at some point in time. Some time later the RF generator also starts. The modulation signal could be anywhere in it's cycle when that happens. The duration of the first and last pulsed output ( not cycle) is therefore affected. I.E the pulse width could be anything up to 500 mS long or as short as next to nothing Kind Regards Kevin
From: Michael Heckrotte [mailto:[email protected]] Sent: Thursday, February 09, 2006 12:28 To: Kevin Harris; EMC PSTC - Post message (E-mail) Subject: RE: Conducted Immunity Question Kevin, Synchronizing such a signal does not make any practical sense. The impact of asynchronous modulation on the uncertainty of the pulse width is infintesimal. The lowest RF frequency is 150 kHz. This yields the longest period, 6.7 usec. The maximum delta in time that the phase of the RF signal could impact the actual leading (or trailing) edge of the modulating pulse is one-quarter of the RF period, which is 1.7 usec. Adding the worst case total of both edges yields 3.3 usec. The exact width of a 1 Hz 50% pulse is 500,000 usec, so the maximum possible uncertainty of the pulse width is +0.0 %, -0.00067 %. Furthermore, at most frequencies in the 150 kHz to 80 MHz band, it is impossible to synchronize the modulation with the RF at both the leading and trailing edges, since there will seldom be an integer number of RF cycles within the pulse width. Best Regards, Mike Michael Heckrotte Engineering Manager, CCS (408) 463-0885 ext. 121 fax: (408) 463-0888 [email protected] From: [email protected] [mailto:[email protected]]On Behalf Of Kevin Harris Sent: Thursday, February 09, 2006 9:00 AM To: [email protected] Subject: Conducted Immunity Question Hello Group, I recently been discussing conducted immunity testing with some colleagues and we have discovered that we have differing opinions on the intent of the standard. In particular we are referring to the EN 61000-4-6 in pulse mode testing. Our product family standard EN50130-4 calls out this base standard with a 1HZ 50% duty cycle pulse rate. The discussion centers around synchronization of the modulation source (1 Hz) and the RF. The standard does not specify explicitly that these signals should be synchronized but one of us feels that it must be so by implication. If one assumes no synchronization ( i.e.. The modulation signal is free running and at some point the RF is enabled ) then the first and last pulses of the train can be of any length (up to 1/2 period) and not the 1Hz 50% pulse called for. The concern here is this would add some unknown uncertainty to the test as well as reproducibility issues. The counter argument to that is, the on off time is really irrelevant, and that any issue arising from uncertain pulse length, should be classed as a failure, as that perhaps is more "real world". What do you feel? Is synchronization important here? Is a non synchronized test system compliant with the standard? Thanks Kind Regards, Kevin Harris Manager, Approvals Group Digital Security Controls 3301 Langstaff Road Concord, Ontario CANADA L4K 4L2 Tel: +1 905 760 3000 Ext. 2378 Fax +1 905 760 3020 Email: [email protected] This transmission is intended to be delivered only to the named addressee(s) and may contain information that is confidential or proprietary. If this information is received by anyone other than the named addressee(s), the recipient(s) should immediately notify the sender by e-mail or by telephone at 905-760-3000 and delete this message. In no event shall this material be read, used, copied, reproduced, stored or retained by anyone other than the named addressee(s), except with the express written consent of the sender. Thank you. - ---------------------------------------------------------------- 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
