Organisations with their own fully accredited EMI / EMC test facilities make good EMI / EMC proven designs. Organisations which are depending on 3rd party labs are at the mercy of the labs, thereby not able to find / identify the real issues and provide solutions. The funny EMI analyser software / test procedures used / followed by the labs push the designers to wall. These labs offer debug services, solutions to the issues and designers who work with this kind of labs loose the confidence. After working with the labs for sometime the customer is finding 'other methods' for solving the EMI issues. Labs run by Government are offering better services but they are very few in numbers.
Bala |------------> | From: | |------------> >----------------------------------------------------------------------------------------------------------------------------------------| |"Grasso, Charles" <[email protected]> | >----------------------------------------------------------------------------------------------------------------------------------------| |------------> | To: | |------------> >----------------------------------------------------------------------------------------------------------------------------------------| |"Conway, Patrick R (bNB Houston)" <[email protected]>, <[email protected]>, "E. Robert Bonsen" <[email protected]> | >----------------------------------------------------------------------------------------------------------------------------------------| |------------> | Cc: | |------------> >----------------------------------------------------------------------------------------------------------------------------------------| |"Brent G DeWitt" <[email protected]>, "Price, Edward" <[email protected]>, <[email protected]> | >----------------------------------------------------------------------------------------------------------------------------------------| |------------> | Date: | |------------> >----------------------------------------------------------------------------------------------------------------------------------------| |04/22/2009 09:04 PM | >----------------------------------------------------------------------------------------------------------------------------------------| |------------> | Subject: | |------------> >----------------------------------------------------------------------------------------------------------------------------------------| |RE: [PSES] SV: "Quiet" Laptop | >----------------------------------------------------------------------------------------------------------------------------------------| Wow – Patrick! Very nicely put. I agree completely. When EMC (or indeed any pursuit) becomes and end in itself – then we truly have lost our way. From: [email protected] [mailto:[email protected]] On Behalf Of Conway, Patrick R (bNB Houston)) Sent:, Wednesday, April 22, 2009 8:27 AM To: [email protected]; 'E. Robert Bonsen' Cc: 'Brent G DeWitt'; 'Price, Edward'; [email protected] Subject: RE: [PSES] SV: "Quiet" Laptop Last week I offered my “professional assistance” to help find quiet laptops. - I’m glad to assist all those that responded. Now I will offer my (less) helpful “philosophical assistance”… Is our community too close to this topic to see it clearly?. Is it the “Can’t see the forest for the trees” phenomena? For instance- when was the last time we had a wide spread EMC problem in the consumer electronics community?> We all know of “little” problems, but when was the last time there was a pervasive problem? Our community, and the EMC Professionals that came before us, should take credit for this achievement. Think about all that is happened in the last 15 (pick a number) years- How many more transmitters and susceptible devices exit now than did back then? How much more closely do these devices co-exist, then they did back then? Yet the widespread interference problems have not arisen. Mind-boggling! IMHO, the people who create the test standards, who set the limits, who design, build, test and manufacture have achieved something huge. Of course, we all (me included) curse the fact that the preipheral that was bought 2 years ago has lost all of its 4 dB of margin. But the fact is it was not built for testing purposes. It was built to be used. As an analogy, I would offer something like a windscreen on a car. Clear glass with some shatterproof capabilites, possibly regulated depending on your local gov’t. But drive the car more than 10 miles and you will start to have tiny, or bigger pock marks, maybe cracks. Drive it ten months and there are rock chips and spider-cracks. Does the glass still meet all of the same test parameters as when driven off the lot? Maybe not. But the car was not purchased to have perfect glass, it was purchased to provide a transportation funciton. Same goes for laptops- They are designed, built and manufactured to run software. Period. They browse the web, send email, store photos, and connect to your printer. And they are portable- designed to be stuck in a purse/briefcase/trunk/boot/overhead compartment. Why single out EMC performance- how many other laptop operations start to deteriorate after purchase? Does the HDD spin at exactly 7200 RPM after it has run 2 months? Does the LCD screen maintain its initial 500 nit brightness after a years operation? Does the AC adapter have the same 90 % efficiency after 2 years of operation? I honestly don’t know- but I also don’t care! It still connects to Google and my printer- so I am satisfied. As an EMC professional I agree that there there is value in owning a laptop that never, ever looses it’s EMC performance. But where do I buy one? Even if a company could charge double the price for those “EMC special” units, no company would build them. The reason is that you would only sell to test labs. That can’t be more than 5 thousand (pick a number) units. And then- after you sell those 5 thousand, no would buy another one for five years (labs are notoriously stingy!) (sorry, “cost concious”). J And if the build quantity is small, then it is not a “Standard” peripheral, so does not meet the requirements for a test peripheral. (any SCCA drivers out there?- same problem exists in SCCA “stock” class: have to have a minimum build/sell quantity, or it is not considered a production model.) So, there it is. We know our enemy, and it is us. We do a darn good job at what we do, and it kills us that no one listens when we say there are wide-spread EMC risks. “Huh, the sky is falling?” says the business owner- “show me the data on the widespread problems”. We build a good product (pick one), it performs to spec, and customers are happy. We should be happy, but alas, we are too close to the topic. We know it could perform better if only… <end of philosophical dallying – now I have to get back to work…> Best- Patrick. OOO- and for amusement purposes only! From: [email protected] [mailto:[email protected]] On Behalf Of Dennis Ward Sent: Thursday, April 16, 2009 8:30 PM To: 'E. Robert Bonsen', Cc: 'Brent G DeWitt'; 'Price, Edward'; [email protected] Subject: RE: [PSES] SV: "Quiet" Laptop Ahhh well said Robert. Dennis Ward Director of Engineering American TCB Certification Resource for the Wireless Industry www.atcb.com. 703-847-4700 fax 703-847-6888 direct - 703-880-4841 From: E. Robert Bonsen [mailto:[email protected]] Sent:: Thursday, April 16, 2009 5:01 PM To: Dennis Ward Cc: 'Brent G DeWitt'; 'Price, Edward'; [email protected] Subject: Re: [PSES] SV: "Quiet" Laptop To add : even when not taking apart a laptop or abusing it physically EMC performance will deteriorate over time. Low-cost mechanical grounding/shielding solutions are often not robust enough to withstand multiple rounds of transport shock&vibe. Conductive cloth wraps or other types of shielding wraps are not robust under mechanical stress. Materials used for chassis parts or shields can oxidize and subsequently inhibit grounding to fingers and gaskets. These are just a few examples. Normal usage and time can and often will wear out commonly used cheap EMC countermeasures that may be used to achieve initial compliance. Even during manufacturing changes happen, tools deteriorate or manufacturing processes are optimized. These tolerances have an affect on the quality of the out-of-the-box EMI performance of a new unit. A good factory audit program will catch deviations to allow fixing these issues, but that still allows batches of units to go out to customers which are not at the same level as the original compliance unit. It also varies from manufacturer to manufacturer how much emphasis is put on maintaining and auditing compliance during the post-compliance test phase of a project, in which tool changes, parts vendor changes and cost-reductions are commonplace. Also, let's not forget that passing compliance to the legal limit in one compliance test situation does not guarantee compliance under all conditions. "My EMC is better than yours" depends highly on the context of the test. -Robert E.Robert Bonsen Sr. Engineering Consultant Orion Scientific Dennis Ward wrote: I do not think any company is going to do the ‘we have less EMC than brand X” for the simple reason that it just won’t work. Laptops now days are built to be fairly rugged, but they are sold to the general public who think precariously placing a laptop on the stove top while checking email and making dinner is ‘normal’ use. Or who perhaps think that cleaning the fan area is just too much work and ‘hey these things are supposed to work like this’. Of course you then have the cleannicks who tear apart their laptops or desktops routinely to ‘clean’ the dust out. I think I fall into that category. Labs may even have a worse time as they open these things probably on a routine basis for various reasons from putting test boards, WLAN transmitters or other ‘support components’ inside to make the test suitable. Cables are also routinely plugged and unplugged. When running a test lab I even had customers that carried the laptop computer by the cables getting it out to the OATS for testing. There it was, in all its glory dangling, swinging, bouncing and flopping around. All of this to say that buying a pristine laptop out of the box with all EMC fingers in place, all shielding in place and all other EMC fixes used to make it compliant in place is different than using a hard handled PC for compliance testing. You cannot expect a laptop or Desk top to maintain all of the originally testing compliance margins after opening is up even once, how can you expect it to be complaint after many openings, fiddling and fudging? This has always been and probably will continue to be a problem child for compliance testing, but getting, keeping and maintaining a compliant laptop or Desk top for compliance testing lies in the world wishes. If you could get a laptop or Desk top that actually met compliance limits, keeping it in that state would probably cost you more than simply going out and buying a new one every once and a while. Dennis Ward Director of Engineering American TCB Certification Resource for the Wireless Industry www.atcb.com. 703-847-4700 fax 703-847-6888 direct - 703-880-4841 From: [email protected] [mailto:[email protected]] On Behalf Of Brent G DeWitt Sent: Wednesday, April 15, 2009 4:25 PM To: 'Price, Edward'; [email protected]. Subject: RE: [PSES] SV: "Quiet" Laptop The rate of laptop model replacement by the manufacturer makes it very difficult to recommend something that you can still buy by the time the EMC community has had enough time to seriously evaluate it. I think Ed’s view on the hopelessness of seeing a manufacturer actually advertise EMC/EMI performance would only happen to products targeted to the paranoid financial market, and I haven’t seen any of that. In a previous life we went out and searched eBay to find laptops that had been discontinued by the manufacturer that we knew to be clean. Good luck! Brent DeWitt Westborough, MA From: Price, Edward [mailto:[email protected]] Sent:: Wednesday, April 15, 2009 5:11 PM To: [email protected]. Subject: Re: [PSES] SV: "Quiet" Laptop > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf > Of Grasso, Charles > Sent: Wednesday, April 15, 2009 12:50 PM > To: [email protected]; Piotr Galka > Cc: EMC-PSTC; John Woodgate > Subject: RE: SV: "Quiet" Laptop > > I sincerely hope that you statement: "Finding a quite laptop > or hub seem to be almost impossible" is wrong! After all > there are many large laptop manufacturers spending zillions > of (in our case) dollars to meet the EMC requirements.!! True, but who markets their product with any claims of EMC excellence? We all may be spending big bucks in our compliance efforts, but all we ever do is slip a required statement in our Users Manual or mold a logo on the bottom of our case. Instead of quietly muttering that "we meet the minimum legally required standards," is anybody daring to say something like "Our Wonderbox has 14 times less annoying electronic radiation!" Or how about something like "Our Wonderbox still keeps working when others have crashed; we built this thing to handle RF noise 3 times stronger than the government said we had to!" Now I doubt your marketing would ever let you get away with anything like that, because claiming how great you are, even if it's true, means alerting the customer to certain problems in life. Marketing usually doesn't want customers to think about problems when they sing their sales pitch. We will have to wait for some maverick company to try this angle; who knows, it just might work. Certainly, RF engineers have a couple of brand names in their head when they think about low-noise pre-amps, so maybe the public reputation of an EMC tough product is possible and desirable. The original poster was asking an interesting question. While you shouldn't choose a "lab queen" product, what's wrong with choosing the quietest among the major brands? But even in this knowledgeable forum, we really didn't have an answer. I'll pose a question; suppose, for your own personal desires, you wanted a very low-emission gadget. If you went to any number of major consumer electronics websites, and looked for compliance data, do you think you would find even one that offers real performance data, not just a bland statement of "meets the minimum requirements," to let you make any intelligent choice? Right now, even we experts can't offer a good answer to the poster's question, because we have no qualitative data. Ed Price [email protected] WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military & Avionics EMC Is Our Specialty - 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.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. 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