Re: Conducted Emissions on Ethernet
In message 041420061600.25253.443FC718000D513562A52206824693CECE020A900A02@comc ast.net, dated Fri, 14 Apr 2006, neve...@comcast.net writes A relatively simple resistive network can be designed for measuring common-mode voltage on Ethernet and many other high-speed interfaces that utilize differential-pair lines, which - with minor modifications - would be perfectly suitable for this application. I have used it for about 10 years, had a paper about it at the Seattle IEEE EMC Symposium (about 8 years ago - coincidently about as long as the standard has been chewed on). Meanwhile it has evolved into a more versatile device than what was described then. But I gues it may be of no interest to people who write standards grin Why don't you tell us more about it, and see? I have problems at present with the revision of EN 55103-1 in respect of conducted emissions: the methods in EN 55022 don't suit every type of port. What interest me most about ports is the conducted emission of a good Late Bottled Vintage into my glass. (;-) -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk 2006 is YMMVI- Your mileage may vary immensely. 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 emc-p...@ieee.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:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Conducted Emissions on Ethernet
A relatively simple resistive network can be designed for measuring common-mode voltage on Ethernet and many other high-speed interfaces that utilize differential-pair lines, which - with minor modifications - would be perfectly suitable for this application. I have used it for about 10 years, had a paper about it at the Seattle IEEE EMC Symposium (about 8 years ago - coincidently about as long as the standard has been chewed on). Meanwhile it has evolved into a more versatile device than what was described then. But I gues it may be of no interest to people who write standards grin Neven -- Original message -- From: John Woodgate j...@jmwa.demon.co.uk In message , dated Thu, 13 Apr 2006, jim.hulb...@pb.com writes We have an ethernet port to which is connected a CAT5 cable. When this cable is routed through an ISN per EN 55022 for conducted emissions measurements, the port is unable to function. What experience have people had with ISNs in this application, or what experience do people have with the alternate test methods (current probe and/or voltage probe measurements)? Since it's taken about 8 years to get even a fragile agreement on conducted emissions in CISPR 22/EN 55022, you'd think that everything would be crystal-clear by ! now. I don't know which edition of EN 55022 you are using by the 1998 edition, with corrigenda 1 and 2 and amendments 1 and 2 says in 9.5.3.1: 'Where normal functioning cannot be achieved because of the impact of the ISN on the EUT, the measurement shall be carried out using the method given in 9.5.3.5.' This in turn refers you to Annex C, C.1.3 or C.1.4. C.1.3 uses a current probe and a voltage probe. C.1.4 uses two current probes and a moveable ferrite 'adjuster'. It takes a long time. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk 2006 is YMMVI- Your mileage may vary immensely. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pst! c discu ssion 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/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: emc-p...@daveheald.com 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/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: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Conducted Emissions on Ethernet
In message of83d77521.a76d1666-on8525714f.004fc2d9-8525714f.00506...@pb.com, dated Thu, 13 Apr 2006, jim.hulb...@pb.com writes We have an ethernet port to which is connected a CAT5 cable. When this cable is routed through an ISN per EN 55022 for conducted emissions measurements, the port is unable to function. What experience have people had with ISNs in this application, or what experience do people have with the alternate test methods (current probe and/or voltage probe measurements)? Since it's taken about 8 years to get even a fragile agreement on conducted emissions in CISPR 22/EN 55022, you'd think that everything would be crystal-clear by now. I don't know which edition of EN 55022 you are using by the 1998 edition, with corrigenda 1 and 2 and amendments 1 and 2 says in 9.5.3.1: 'Where normal functioning cannot be achieved because of the impact of the ISN on the EUT, the measurement shall be carried out using the method given in 9.5.3.5.' This in turn refers you to Annex C, C.1.3 or C.1.4. C.1.3 uses a current probe and a voltage probe. C.1.4 uses two current probes and a moveable ferrite 'adjuster'. It takes a long time. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk 2006 is YMMVI- Your mileage may vary immensely. 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 emc-p...@ieee.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:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Conducted Emissions on Ethernet
From: jim.hulb...@pb.com [ mailto:jim.hulb...@pb.com] Sent: Thursday, April 13, 2006 7:38 AM To: emc-p...@ieee.org Subject: Conducted Emissions on Ethernet We have an ethernet port to which is connected a CAT5 cable. When this cable is routed through an ISN per EN 55022 for conducted emissions measurements, the port is unable to function. What experience have people had with ISNs in this application, or what experience do people have with the alternate test methods (current probe and/or voltage probe measurements)? We are trying to establish a test procedure that yields repeatable measurements and hopefully measurements that are correlatable to what other labs may measure. Thank you. Jim Hulbert, Principal Engineer GMSE/TSO/Compliance Engineering Pitney Bowes Jim: A few weeks ago, I almost had to face trying to filter an Ethernet cable. My first attempt was to use an Quell EESeal connector insert filter, with a capacitance of 5000 pF from each pin to ground. This produced too much loading (desired signal reduction), and the Ethernet link would not function. So, the only little fact I can add is that 5000 pF (to ground) is too capacitance for the Ethernet interface. Ed Price ed.pr...@cubic.com WB6WSN NARTE Certified EMC Engineer Technician Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military Avionics EMC Is Our Specialty - 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/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: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Conducted Emissions on Ethernet
Jim, I am not a test-house, so I don't have experience with various ISNs. However, I have done a considerable amount of work in common-mode voltage and current measurements, as well as investigating imbalance (i.e. mode conversion) in differential-signaling, especially in the hi-speed signaling including Ethernet arena. So maybe I can give a little advice here. I don't know what's wrong with your ISN, but for measuring conducted emission (either CM currents or CM voltages) on high-speed differential signal lines I would never use anything that has RJ45 or similar connectors on it. Just conversion in the connectors and the un-twists of the cable in the area around the connectors can considerably affect common-mode voltages and currents on the signal line, so the measurement results are uncertain. If the un-twists of the twisted pairs at the connector are bad, that can cause considerable crosstalk between the pairs as well. Whatever the test method, the level of balance on the differential pairs must be preserved and not affected, or the results can be anything. For that reason I strongly prefer the clamp method over ISN. Clamp preserves the integrity of the signal line, and ISN is not well-defined in that respect. Some EMC test houses seem not to be aware of that, and I believe that even the ISN manufacturers are not paying attention to it. If I had to use ISN, for whatever reason - maybe for ease and speed of measurement compared with the clamp-test, I'd cut-off the RJ45 receptacles (and maybe some associated segments in the box) from the ISN. I would also cut off the RJ45 plugs from the ends of the cables that connect to it, design a better transition (with better balance, less mode conversion and crosstalk) between the cable that connects the ISN to DUT and from ISN to AUX, and then I'd verify the balance on a 4-port network analyzer. Hard-wiring the ISN into the signal line might do it, keeping extreme care to preserve the balance on the diff pairs. No time or space to elaborate more, but that is essentially keeping the twists of each pair tight and together, and at the same time separating each pair from its neighbor. Regards, Neven -- Original message -- From: jim.hulb...@pb.com We have an ethernet port to which is connected a CAT5 cable. When this cable is routed through an ISN per EN 55022 for conducted emissions measurements, the port is unable to function. What experience have people had with ISNs in this application, or what experience do people have with the alternate test methods (current probe and/or voltage probe measurements)? We are trying to establish a test procedure that yields repeatable measurements and hopefully measurements that are correlatable to what other labs may measure. Thank you. Jim Hulbert, Principal Engineer GMSE/TSO/Compliance Engineering Pitney Bowes- 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/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: emc-p...@daveheald.com 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/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: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
