Amen, Derek, Ivory tower views are exceptionally easy to espouse, impossibly hard to make money in such an edifice.
Michael Violette, P.E. Director American Certification Body [email protected] +1 240-401-1388 Join ACB for a training seminar in Milan on 5 and 6 June, 2019: https://acbcert.com/seminars/2019-Wireless-Approvals-Workshop/2019-Wireless-Approvals-Workshop.html > On Apr 17, 2019, at 11:47 PM, DEREK WALTON > <[email protected]> wrote: > > Whoah Ed, > > you just landed along side Ken and Ghery! > > I have to strongly oppose some of your views on what the test lab should or > shouldn’t Know/do. Wow, have you any idea of the variety of equipment that > roles in the lab door, and the complexity of it? NO, it is NOT the labs job > to understand the EUT, other than how to interpret the standard so it can be > tested. It is totally unreasonable to expect a test person to muse the > subtleties of sub micron silicon one day then the ramifications of 10,000 psi > hydraulic pumps the next. I doubt few could listening in. > > Having had the luxury of “visiting" well over 350 labs around the globe over > the last 23 years I’ve gathered quite a bit of insight on lab operations and > their clients. I happen to have worked in one for 40 years and owned one or > two for 30+ years. So much of the email thread is huff and puff. IN the sales > world it would be called FAD: fear and disillusionment. > > Lets set some records straight: > > The majority of labs do a superb job with all the constraints they are under. > > An ISO 17025 assessment cannot prevent mistakes, but it does make provisions > for just about all foreseeable, and quite a few unforeseeable problems. > > Everyone can have a bad day: that includes test engineers/technicians. > > Technology evolves, and what’s true at one point may not be true sometime > later. Unless everything is checked to the nth degree, EVERY time, things > will escape notice. > > For all those calling out check after check, I bet under the same breath they > are complaining about the cost of testing! > > And for the record, those critical of overseas test labs should go and pay a > visit: most times they are careful to incredible levels running tests. > > If a manufacture brings a device in for testing, no-one, that’s NO-ONE knows > it better than he does. He has a responsibility to understand the testing his > device will be subjected to and its behavior, heck, he’s supposed to have > designed the device to pass the test! That includes support equipment too! > > A lab should help someone who’s a novice in the EMI field to avoid pitfalls, > that’s professional curtesy. It’s also in the labs interest as they don’t > want someone packing up and leaving a few hours into the day and leaving the > rest of the day not generating revenue. > > This topic is huge, and I hear so called experts spout contentious opinions > that are ill founded. It’s particularly distasteful especially in a > professional form such as this as it forms false opinions in peoples minds, > especially as some of these experts have a high platform from which to > pontificate. There isn’t a rampant problem in the testing community, and many > hardworking technicians, engineers, managers, QA people, Assessors, assessing > bodies and even test witnesses would be very aggrieved to hear some of these > statements. > > Testing is a team mentality, not a glass wall mentality. And valid data is > the responsibility of BOTH parties. It requires capable people who have a > systematic work approach. So unless ALL the full details are known spreading > scuttlebutt or opinions of what could have/should have, is NOT helpful. > > My 10 cents as I have to go back and tend to a test I’ve been running since > 6am. > > Shalom. > > Derek. > > > >> On Apr 17, 2019, at 6:21 PM, Edward Price <[email protected] >> <mailto:[email protected]>> wrote: >> >> Derek: >> >> When a test lab is engaged to perform testing on a product, the test lab >> owes the client, at the minimum, accurate test data. However, it is not the >> “chamber” that delivers that assurance of quality workmanship, rather it is >> the EMC Engineer in charge of that facility. When the client walks in the >> door, he expects a knowledgeable testing operation, not an environment that >> seems to be learning as they go. Not recognizing Ambient noise polluting the >> Operational emission data is a failure to deliver the expected professional >> level of competence. To me, it seems pretty clear that the testing lab is at >> fault. If the problem was rapidly recognized by them, and a new set of data >> was taken, then the problem is mainly one of embarrassment of the testing >> lab’s people. However, if it goes on without recognition, if the lab lets >> the client take his equipment home with the assumption that the equipment >> has failed, then the longer it goes on, the greater the testing lab’s error >> and financial responsibility becomes. Perhaps the testing lab never noticed >> the problem on their own? That would have been a pretty serious indication >> that the testing lab just wasn’t ready to deliver professional quality >> testing services. >> >> Another interesting comment was that there was difficulty in “setting up” >> the test specimen and its support equipment. A good test lab will know what >> a customer needs to supply long before the test date. Time should be >> budgeted for the setup and trouble-shooting of ancillary devices, and the >> customer should be warned that home-brew support equipment may cause EMI >> issues all on their own. A good test lab will make some suggestions about >> best practices, but alert the customer that it may be necessary to >> ameliorate support equipment problems before EUT testing can begin, and this >> may entail additional time and materials needed to make the support >> equipment quiet or immune enough to allow testing. Further, a good test lab >> should always expect some set-up problems, and be ready to surmount these >> with a plentiful junkbox of rolls of aluminum foil, conductive tape, bond >> straps, shielded boxes, knitted wire mesh, capacitors, inductors, ferrite >> beads, isolation transformers, sheet metal and a decent assortment of common >> hand tools. In short, if your customer says his gadget needs an external >> water chiller, the test lab should have already thought about ground loops, >> how to get water in and out of the chamber, and have considered what >> problems a water chiller might induce in the lab’s electrical environment. >> The test lab’s customer should not feel that the test lab was unprepared to >> receive him or that the test lab was anything less than expert in >> integrating the test specimen and support equipment into the test chamber. >> >> It would appear that the selected test lab was just not ready for prime time. >> >> >> Ed Price >> WB6WSN >> Chula Vista, CA USA >> >> From: DEREK WALTON [mailto:[email protected] >> <mailto:[email protected]>] >> Sent: Wednesday, April 17, 2019 12:08 PM >> To: [email protected] <mailto:[email protected]> >> Subject: Re: [PSES] Question re: Measuring a signal in a noisy environment >> >> Interesting discussion, not surprising I have a little empathy, and a whole >> slew of disagreement with both Ken and Ghery ( both Chaps I have a lot of >> respect for ) on this one. >> >> How best to respond is the question? >> >> Cheers, >> >> Derek Walton. >> >> >> On Apr 17, 2019, at 1:12 PM, Bill Stumpf <[email protected] >> <mailto:[email protected]>> wrote: >> >> Absolutely agree with Ken. >> >> Bill Stumpf >> Lab/Technical Manager >> D.L.S. Elecronic Systems, Inc. >> >> >> >> From: Kenneth Wyatt [mailto:[email protected] >> <mailto:[email protected]>] >> Sent: Wednesday, April 17, 2019 12:21 PM >> To: [email protected] <mailto:[email protected]> >> Subject: Re: [PSES] Question re: Measuring a signal in a noisy environment >> >> Boy, I have heard all sorts of horror stories from clients with >> knowledgeable EMC backgrounds who have witnessed sloppy, or just plain >> wrong, procedures used in commercial EMC test labs. In a lot of cases, the >> technicians operating these tests have limited background in EM theory and >> poor knowledge of the actual tests they are running and standards the tests >> are based on. >> >> Just because a test lab is assessed per IEC 17025, doesn’t mean much unless >> they show evidence the documented procedures are actually being followed. >> >> Many test labs fail to perform frequent verification tests to confirm the >> measurement system is accurate and is repeatable from one day to the next. >> When I worked for HP, we did a daily verification test using an RF generator >> connected to the antenna cable to ensure the back-end system measured the >> same as the day before. We also ran comb generator tests frequently. >> >> I always suggest to my clients to make their preferred test lab measure a >> client-owned comb generator prior to any testing in order to ensure the >> chamber continues to be reasonably consistent before real measurements are >> taken. >> >> It’s also very important to understand the test standards and EUT >> configurations well enough to ensure the test technician is setting up >> things correctly. I know of one case where the EUT cabling was configured >> wrong and their client repeatedly had emissions failures over weeks of >> retesting until the correct configuration was pointed out in the standard. >> >> Taking photos of the test setup is very important for day to day test >> consistency. A difference in one cable position can completely throw off >> repeatability and thus, mislead any troubleshooting efforts. >> >> What about ESD simulators? When was it verified last? Does the test lab even >> have the means to verify the correct tip voltage and pulse characteristics? >> >> Is all the measurement equipment calibrated and cal tags current? >> >> I could go on… >> >> My colleague, Ghery Pettit wrote a recent blog on the subject for >> Interference Technology: >> https://interferencetechnology.com/emc-laboratory-selection-audit-items/ >> <https://interferencetechnology.com/emc-laboratory-selection-audit-items/> >> >> Cheers, Ken >> >> _______________________ >> >> I'm here to help you succeed! Feel free to call or email with any questions >> related to EMC or EMI troubleshooting - at no obligation. I'm always happy >> to help! >> >> Kenneth Wyatt >> Wyatt Technical Services LLC >> 56 Aspen Dr. >> Woodland Park, CO 80863 >> >> Phone: (719) 310-5418 >> >> Web Site <http://www.emc-seminars.com/> | Blog <https://design-4-emc.com/> >> The EMC Blog (EDN) >> <https://www.edn.com/electronics-blogs/4376432/The-EMC-Blog> >> Subscribe to Newsletter >> <http://www.emc-seminars.com/Newsletter/Newsletter.html> >> Connect with me on LinkedIn <https://www.linkedin.com/in/kennethwyatt/> >> >> >> >> On Apr 17, 2019, at 10:46 AM, Grasso, Charles <[email protected] >> <mailto:[email protected]>> wrote: >> >> To those wondering what the background and conclusion to that question was: >> >> Background: Our testing was performed in a newly minted chamber so >> proper >> EMC installation of our product was challenging. >> Effect: Ingress of high levels of external bb noise. >> Result: Proper install eliminated the external noise and >> now the system passed. >> >> Concern: While I accept that proper installation and operation of our system >> is our >> responsibility, I had expected that the tester would point to the excessive >> ambient >> and indicate that our data may not be valid. An inexperienced customer would >> have left thinking that their product had failed. >> >> Am I wrong? >> >> >> Thanks! >> >> Charles Grasso >> W: 303-706-5467 >> >> - >> >> - >> ---------------------------------------------------------------- >> 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 >> <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/ >> <http://product-compliance.oc.ieee.org/> can be used for graphics (in >> well-used formats), large files, etc. >> >> Website: http://www.ieee-pses.org/ <http://www.ieee-pses.org/> >> Instructions: http://www.ieee-pses.org/list.html (including how to >> unsubscribe) <http://www.ieee-pses.org/list.html> >> List rules: http://www.ieee-pses.org/listrules.html >> <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 > <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/ > <http://product-compliance.oc.ieee.org/> can be used for graphics (in > well-used formats), large files, etc. > > Website: http://www.ieee-pses.org/ <http://www.ieee-pses.org/> > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) <http://www.ieee-pses.org/list.html> > List rules: http://www.ieee-pses.org/listrules.html > <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://www.ieee-pses.org/list.html (including how to unsubscribe) 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]>
