An old clause in C64 and I believe the EU ITE test set-up indicated you could stop adding identical I/O's the X+1 I/O emission changes by less than 2 db. I remember, but don't have an old HP study on the edition of fiber optic transceivers and it showed that it never really stopped increasing but after 10 or something on that order the plot became asymptotic. Since transceivers were expensive we usually targeted 10 or so and did a little checking that we met the less than 2 db thing. That was the case for 1 blade with 10 or more transceivers per blade. I might also have multiple blades each with its own 10 or more transceivers. Now we started jamming in blades until we hit the magic 2 db or less, and in practice that turned out to be under 4 - and typically less. So eventually and without a huge number of tries we got the system configuration we needed. The conducted emissions were more problematic because they really depend on the system load - and we would bracket that with minimum number or blades, and a maximum number of blades - but some of those might be power loads only. We documented in the test records the number used and why we stopped at that number.
The old NEBS standards indicated that you either had to use 100% of the ports at 50% of capacity or 50% of the ports at 100% of the capacity. Which meant for those guys we were forced to increase the number of ports and blades - but we never saw the system go out of specification using the first process and then going to NEBS. NEBS Of course by then you were committed to big bucks in testing since they were going to start the chassis on fire and try to etch away the outer layers of our PCBS with acidic atmospheres. But that was a cost/benefit ratio that the marketing and sales guys had to justify. NEBS is the US version of EU telecom. To drive this whole smear we used an Ethernet traffic generator such as an Ixia box and set up a series of LANS and ports that would allow us to daisy chain the data through all of the ports and go back to the Ixia box. 1) were different ground references because the Ixia traffic generator was connected somewhere other than the EUT power connections, and generally off the ground plane, in this case we were fiber optic so we didn't have to mess around with the put a ferrite on cables leaving the ground plane or not - depending on US or EU requirements, 3) we could set the system to look for dropped packets, jitter, and latency during immunity tests. Too many dropped packets was a failure even if the system requirements could handle it - our internal specification wouldn't accept it. I don't know if any of those clauses still exist - I haven't looked in a long time - but I'm not sure it is a lot different than checking the emissions at 120 and 230 at a few spots to see if one or the other is worse case, and one has to limit infinity to something that is doable and sane. Gary From: Grasso, Charles [mailto:[email protected]] Sent: Wednesday, December 28, 2011 11:28 AM To: [email protected] Subject: Re: [PSES] What means do you use to exercise Ethernet telecom ports? Hello Jim, We hook up to the test labs internet infrastructure and stream data back and forth to our STBs. This test methodology has all the downsides that James has as upsides on his test method - with one exception. It's easy to justify. After all how can you argue with exercising the port as intended.? Our external equipment has included switches/routers/PCs/other STBs in various flavors and (on the whole) its been OK. One does have to be judicious to pick trusted sources for the ubiquitous electronics though!! On a side note: I have always held the belief that a simple ping test will result in the full emissions profile. (And based on my experience I have no reason to change my mind!) I started that way and ran into the justification issues as alluded to earlier. Now - our boxes have at the most two ENet ports. The mind boggles at the logistics of testing a large set of I/O.!! Best Regards Charles Grasso Compliance Engineer Echostar Communications (w) 303-706-5467 (c) 303-204-2974 (t) [email protected]<mailto:[email protected]> (e) [email protected]<mailto:[email protected]> (e2) [email protected]<mailto:[email protected]> From: [email protected] [mailto:[email protected]] On Behalf Of Knighten, Jim L Sent: Tuesday, December 27, 2011 5:05 PM To: [email protected] Subject: What means do you use to exercise Ethernet telecom ports? I am curious what means people are using to exercise Ethernet telecom ports when testing for conducted emissions according to CISPR 22 and conducted immunity according to CISPR 24? Do you use an external piece of equipment (AE) to send Ethernet traffic? If so, what do you use and do you like it? My particular interest is 1000BaseT (gigabit Ethernet), but the question is more general. Thanks in advance, Jim __________________________ James L. Knighten, Ph.D. EMC Engineer Teradata Corporation 17095 Via Del Campo San Diego, CA 92127 858-485-2537 - phone 858-485-3788 - fax (unattended) - ---------------------------------------------------------------- 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 <[email protected]<mailto:[email protected]>> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. 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 <[email protected]<mailto:[email protected]>> Mike Cantwell <[email protected]<mailto:[email protected]>> For policy questions, send mail to: Jim Bacher <[email protected]<mailto:[email protected]>> David Heald <[email protected]<mailto:[email protected]>> - ---------------------------------------------------------------- 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 <[email protected]<mailto:[email protected]>> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. 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 <[email protected]<mailto:[email protected]>> Mike Cantwell <[email protected]<mailto:[email protected]>> For policy questions, send mail to: Jim Bacher <[email protected]<mailto:[email protected]>> David Heald <[email protected]<mailto:[email protected]>> - ---------------------------------------------------------------- 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 <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. 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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
