[no subject]
Group: What happened to all the emc discussions? I got off the system for a while, and now its all product safety. Did the emc people start their own separate group? Lou G. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: Mars Lander EMC problem?
Sen. McCain is on the committee that oversees NASA. He recently said that the basic problem is poor management. IMHOP he's right. lou At 02:41 PM 3/30/2000 -0500, you wrote: Tony, I don't think it was actually EMC. The report I saw on CNN said the legs opened with a jolt, fooling the sensors which were supposed to cut the retro rockets when they detected the shock of landing. Scott Lacey It looks like Scott Lacey is right, thank you! I made the assumption that spurious signal was electrically generated. It appears it was mechanically or magnetically generated! Is a Hall effect sensor microphonic? Well, I guess another lesson for me not to jump to conclusions before all the data is available! Tony Colorado Below is an excerpt from the complete NASA report. Premature shutdown of descent engines. PLAUSIBLE. A magnetic sensor is provided in each of the three landing legs to sense touchdown when the lander contacts the surface, initiating the shutdown of the descent engines. Data from MPL engineering development unit deployment tests, MPL flight unit deployment tests, and Mars 2001 deployment tests showed that a spurious touchdown indication occurs in the Hall Effect touchdown sensor during landing leg deployment (while the lander is connected to the parachute). The software logic accepts this transient signal as a valid touchdown event if it persists for two consecutive readings of the sensor. The tests showed that most of the transient signals at leg deployment are indeed long enough to be accepted as valid events, therefore, it is almost a certainty that at least one of the three would have generated a spurious touchdown indication that the software accepted as valid. The software - intended to ignore touchdown indications prior to the enabling of the touchdown sensing logic - was not properly implemented, and the spurious touchdown indication was retained. The touchdown sensing logic is enabled at 40 meters altitude, and the software would have issued a descent engine thrust termination at this time in response to a (spurious) touchdown indication. MOST PROBABLE CAUSE OF LOSS OF MISSION --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: EMC/PSTC/NEBS/TREG
Im with Dave. it is getting too cumbersome. we are going to have to split it up eventually. Lou At 03:51 PM 3/28/2000 -0500, you wrote: Average number of messages is now between 30 and 50 a day. And people want more! I wish I had enough free company time to participate in this mountain of mail. We need to increase the quality and substance of the messages rather than to increase the amount. Dave George Unisys -Original Message- From: pmerguer...@itl.co.il [mailto:pmerguer...@itl.co.il] Sent: 17 March, 2000 4:04 AM To: emc-p...@majordomo.ieee.org Subject: EMC/PSTC/NEBS/TREG Dear All, DO NOT SPLIT! I AM ALSO IN FAVOR OF MIGRATING TREG AND NEBS GROUPS INTO TO THE EMC/PSTC LIST. ARE YOU ALL IN FAVOR? Peter Merguerian Managing Director Product Testing Division I.T.L. (Product Testing) Ltd. Hacharoshet 26, POB 211 Or Yehuda 60251, Israel Tel: 972-3-5339022 Fax: 972-3-5339019 e-mail: pmerguer...@itl.co.il website: http://www.itl.co.il --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
modest proposal
To all who replied: Thanks for the quick and hearty responses! I certainly agree that the world does not need another artificial language like esperanto. Some people are better at languages than others, though, and i have seen some very good engineers having to really struggle with ours. Meanwhile, I have it on excellent authority that the Spanish Government is about to simplify the Spanish language, eliminating all the accent marks to make an easy, logical language even easier to learn and to use. Oh well, lets get back to work. Best Regards, Lou --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
A modest proposal.
Group: Having subscribed to this group for over a year now, I am really impressed by how easily we hold technical bull sessions with emc engineers from all over the world. This is a fabulous service of the ieee. There is only one problem with it: ya gotta speak english. If an engineer can't speak english, he or she is really handicapped nowadays. Like it or not, it has become the de facto world language. But english is a very hard language to learn. Linguists rank it up there among the most difficult in the world. Our spelling is really screwy, for one thing. I hate to see some of our overseas clients - smart people and good engineers - having to struggle with the inconsistencies of the language. Many of our own college graduates have problems with grammar and spelling. As a communications engineer, i can tell you that this is not a good situation. I think we ought to simplify it. If we can virtually eliminate the word he and erase the suffix -man due to political correctness, we certainly can substitute thru for through and enof for enough and make a few simple changes like that. Maybe there ought to be a new European Standard: a simplified version of English for international use. Sort of a CE-Mark version of English to make life a bit it easier for the rest of the world, and to encourage more smart people to participate in valuable forums like this one. Comments welcomed. Regards, LOUIS T. GNECCO M.S.E.E., PRESIDENT TEMPEST INC. 112 ELDEN ST. HERNDON VIRGINIA 20170 (703)TEMPEST (836-7378) CERTIFIED ELECTROMAGNETIC COMPATIBILITY ENGINEER CERT. # EMC-000544-NE CERTIFIED ELECTROSTATIC DISCHARGE CONTROL ENGINEER: CERT.# ESD-00143-NE --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
A-t/m vs A-t/cm
Group: I want to make sure I did this right. I was trying to determine the permeability of this material. The B-H curve shows Flux density B in Teslas. (1 tesla = 10,000 Gauss, ) But the Field Strength H is in A/cm. How do I convert this into something I can use like Oersteds or A/m? No guessing, please. I would appreciate hearing from someone with experience dealing with these units. Arun? Hans?? Are you out there?? help!! Regards, Lou - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Shielded Enclosures Standards.
David, The best one that is generally available to the public is still MIL-STD-285. It is available from the us govt's DODSSP: dept of defense single source point, in philadelphia. http://www.dodssp.daps.mil/ . The IEEE has a standard 299, but in my humble opinion it was written by a bunch of smart, well-meaning folks who never did many ( or ANY) real shielding effectivess testing. It is somewhat impractical and I would not recommend it, but it is good to have in case someone tries to force you to use it. Someone said that the DoD had adopted it years ago, but we do a lot of shielding effectiveness tests for them and I have NEVER seen IEEE 299 called out. The IEEE publishes an excellent book by Leland Hemming: Architectural Electromagnetic Shielding Handbook but this has to do more with the design of shielding systems. Still, he has some sample contracts in the back. It is worth looking at. The best book of all, in my opinion, is: THE SHIELDED ENCLOSURE HANDBOOK see: http://www.tempest-inc.com/pubs2.htm This is the definitive guide for the buyer, builder, tester and user of electromagneticlally shielded rooms. It contains copies of MIL-STD-285 (and MIL-STD-220, which you will also need.) It contains information that is available nowhere else: honest, practical advice that will save you time, money and a lot of grief. The author has good credentials a lot of experience testing, buying, using and supplying shielded rooms. He is also a genius, and an all-around good guy. (i wrote it.);) Regards, Lou LOUIS T. GNECCO, M.S.E.E., PRESIDENT TEMPEST INC. 112 ELDEN ST. HERNDON, VIRGINIA 20170 CERTIFIED ELECTROMAGNETIC COMPATIBILITY ENGINEER: CERT. # EMC-000544-NE CERTIFIED ELECTROSTATIC DISCHARGE CONTROL ENGINEER: CERT. # ESD-00143-NE - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: Chamber Grounding
Don, scott has a good point: if you use a single point grount you might as well use an isolation transformer to put the room on its own ground. This is a great way to set up yur room, but it can lead to the problems scott mentioned and one other big one: if your room is on its own ground (i.e. has its own power) and the rest of your lab runs off the building's power, you can ruin a receiver or spectrum analyzer when you try to connect it to a feed thru on the room's wall. In our lab, we took extreme measures to avoid this. You would have to REALLY TRY to power an instrument from anything other than the shielded room's power. You would have to move a safe or a refrigerator before you could do it wrong. We have had lots of clients thru our lab in the ten plus years we've been in there, and have never had a problem. Most of these are young hands on type engineers too. They like to twist knobs and try things, vs. just watching us work. We encourage them to do that but brief them when they come in, then we make it almost impossible for them to mess up. So far, so good! :) lou At 10:49 AM 11/3/1999 -0500, you wrote: Don, One other point that needs mentioning re. chamber grounding is the safety issue. When our chamber was installed, the electrician connected a #6 ground wire to an existing bus block that is wired to a driven rod in the basement. While working above the chamber he got a nasty shock when he came into contact with a metal air-conditioning duct. A piece of metal conduit with one end pressing against the chamber wall would exhibit a fat blue spark when the other end touched any grounded metal. It turned out that the ground rod clamp had become corroded. The leakage current from the line filters supplying the chamber is several amperes, which certainly could be lethal. Your single-point ground should be carefully checked (and periodically rechecked). I would recommend connecting the wire to the rod using TWO clamps of the one-piece type for redundancy. Conductive grease helps prevent corrosion. Scott Lacey -Original Message- From: umbdenst...@sensormatic.com [SMTP:umbdenst...@sensormatic.com] Sent: Wednesday, November 03, 1999 9:25 AM To: emc-p...@ieee.org Subject:FW: Chamber Grounding Our chamber is grounded/isolated per the instructions of the vendor. We have one copper clad ground rod installed through a hole drilled in the slab adjacent to the corner of the semi-anechoic chamber. Other grounds are isolated from the chamber (conduits, air pipes, water pipes, service entrance safety ground, etc.). The ground comes from the ground rod, not the service entrance. 1) Is single-point-ground as described above for Tempest? Is the degree of isolation useful for typical commercial work? The chamber spec is 100 dB isolation. For our immediate work, 60 dB of isolation is adequate. Is there any correlation between chamber isolation and effectiveness of the ferrites for the uniform field required for immunity testing? Is there some other observable sensitivity such as degraded RF measurements that would result from not observing the isolation? What would the manifestations be? 2) Using the isolation as described above, has anyone experience ground loop problems between the service entrance power and the local chamber power distribution due to the single point ground concept defined above? Don Umbdenstock Sensormatic - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: Laser Standards
Group, There is actually a precedent for all this. It is called an Inter-Library Loan and librarians do it all the time, including corporate librarians. It works like this: I need a document, say a EUROPEAN STANDARD. Your Company Library has it. I ask my librarian to ask your librarian for it. If it is ok with your company, your librarian sends it LIBRARY TO LIBRARY, complete with receipts, accountability, and a paper trail. My librarian then checks it out to me, and I become responsible for it. Now I can't just keep it, because it is due back on a certain date and my librarian will get after me to return it. This is what librarians do, and it works. Lou - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
broadband/narrowband
-Original Message- From: Muriel Bittencourt de Liz [SMTP:mur...@grucad.ufsc.br] mailto:[SMTP:mur...@grucad.ufsc.br] Sent: Thursday, October 07, 1999 5:43 AM To: Lista de EMC da IEEE Subject: broadband narrowband emissions Group, I'd like to have a clear definition of what are narrowband and broadband emissions. This question may seem very plain for many members of EMC-PSTC, but I always heard/saw this definition for emission and I still couldn't make them clear to me.. Thanks in advance for your attention Regards Muriel *** Muriel: Arun gave a very good explanation, and here is another one: Below is an excerpt from one of our books, PROBLEMS AND SOLUTIONS IN WIRELESS COMMUNICATIONS AND EMC. I have used this explanation in some of my courses, and people seem to understand it pretty well. I hope this helps. *** © Copyright 1999 by TEMPEST INC. Chapter 7. Converting Broadband To Narrowband Units And Vice Versa. This is a source of much confusion to new EMC engineers. Lets look at a part of the frequency spectrum, say from 20 to 30 MHz : (1.) When you only have one frequency, say 25 MHz, and its amplitude is 1 volt rms, the spectrum looks like this: 20 MHz.|_30 MHz .25 MHz (2.) Now lets say you have a waveform composed of 2 signals. One is at 24 MHz and one is at 26 MHz , each one being 1 volt rms. If you look at either signal alone, its amplitude is still 1 volt rms, but if you look at them together, the amplitude of the combined wave form will be somewhat greater. 20 MHz___|__|___30 MHz 24.26. (3.) Now lets say that you have a whole lot of frequencies: 20 MHz.||30 MHz if you take a tiny piece of the spectrum, you may only see one signal _|__ © Copyright 1999 by TEMPEST INC if you take a piece that is 1 MHz wide, you will see several ||| if you take a piece that is 2 MHz wide, you will see even more || and the more you see, the more energy you have. Some signals are broadband. Their spectrum looks like the one in (3.) above. One example is a square wave. A better example is an impulse. How do you describe the amplitude of these signals? If you measure them with a 1 MHz bandwidth you will get one answer, if you measure them with a 10 MHz bandwidth you will get a different answer. This is why we have broadband units. With broadband units we can say that this signal gives you x volts for every megahertz-sized piece of the spectrum that you use to measure it. For example, if the signal in (3) gives you 10 volts when you take a 1 MHz piece, it will give you 20 volts if you take a 2 MHz piece, and 30 volts if you take a 3 MHz piece. The bigger the bandwidth, the more volts you get. In this case, we would say that the signal gives you 10 volts per Megahertz. Now lets say that you look at this signal with a 10 MHz bandwidth: © Copyright 1999 by TEMPEST INC We would see 10 Volts/MHz x 10 MHz bandwidth = 100 Volts if we look at it with a 2 MHz bandwidth, we would see 10 volts/MHz x 2 MHz = 20 Volts what if we only looked at it with a 500 kHz bandwidth? 500 kHz = 1/2 MHz 10 V/ MHz x 1/2 MHz = 10 x 1/2 = 5 Volts now lets do some problems: **© Copyright 1999 by TEMPEST INC. For more info, see: http://www.tempest-inc.com/pubs1.htm Regards, Lou . LOUIS T. GNECCO M.S.E.E., PRESIDENT TEMPEST INC. 112 ELDEN ST. HERNDON, VA 20170 (703) TEMPEST (836-7378) CERTIFIED ELECTROMAGNETIC COMPATIBILITY ENGINEER: CERT.# EMC-000543-NE CERTIFIED ELECTROSTATIC DISCHARGE CONTROL ENGINEER: CERT. # ESD-00143-NE CERTIFIED TEMPEST PROFESSIONAL, LEVEL II .. - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Laser Standards
Rick, We have a copy and you can borrow it. I think that the cost of these standards is ridiculous, it is totally unjustified, and that we all ought to circumvent it by informally lending each other copies. There is absolutely nothing illegal about that. Regards, Lou s At 03:03 PM 10/7/1999 -0600, you wrote: My company uses a 2 mw laser to align a reverse screen projector system. It is my understanding that this low power laser falls under the classification of Category 1 and is by definition, relatively safe. I thought I would purchase a copy of EN 60825 to ensure that we have address proper labeling and markings. Unfortunately this standard has 6 parts and could cost upwards of $800-1000. Can someone suggest which section I should order to identify the respective marking requirements. Thanks in advance... Rick Busche Evans Sutherland rbus...@es.com - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Results of SLIM Recommendations
Joe: check this web site: http://europa.eu.int/comm/dg03/directs/dg3d/d1/eleng/index.htm it's all there. click on emc, then click on slim. bottom line: they are going to review the emc directive. ( no surprise there.) Lou . LOUIS T. GNECCO M.S.E.E., PRESIDENT TEMPEST INC. 112 ELDEN ST. HERNDON, VA 20170 (703) TEMPEST (836-7378) CERTIFIED ELECTROMAGNETIC COMPATIBILITY ENGINEER: CERT.# EMC-000543-NE CERTIFIED ELECTROSTATIC DISCHARGE CONTROL ENGINEER: CERT. # ESD-00143-NE CERTIFIED TEMPEST PROFESSIONAL, LEVEL II .. At 04:02 PM 10/5/1999 -0700, you wrote: Is anyone aware of the results of the SLIM III recommendations per the Report of the SLIM III Team on Electromagnetic Compatibility Directive (89/336/EEC as amended) dated 9/98. I had heard that the Commission was going to produce a Communication to the Council of Ministers and the European Parliament earlier this year. I am particularly interested in the CE+CE=CE issue. All responses are appreciated Regards Joe Martin EMC/Product Safety Engineer marti...@pebio.com - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Multi-Standards Haze
George: It's OK to tell them I sent it. They must be pretty tired of hearing me talk about this by now, anyway. The thing is, our military services did not have a hidden agenda. They needed to produce clear, enforceable standards for a very important reason: to keep american kids from getting killed. Ive been on both sides, and I have seen how things get done. In the government, there is usually a huge committee. Most of the participants dont contribute much. Then there are one or two real experts who have the time and the facilities to develop something that is pretty good. Then everybody shares the credit (or the blame.) Ive seen how some industrial standards are developed, and I have to say that Im pretty disappointed. The government is actually good at certain things: rule-making is one of them. When you think about it, our federal government military have done some pretty good things: besides protecting our country, they built the panama canal which was one of the wonders of the world at the time, found a cure for malaria (Walter Reed) developed most of the tools now used in deep sea exploration and - oh yes - they put a man on the moon. They waste huge amounts of money, but a lot of that is due to the politicians that WE ELECT! ;) Lou At 11:12 AM 10/1/1999 -0400, you wrote: See a response received below. Author's name deleted as I did not ask if I could post the response. My comment: Who ever thought that a Federal Government, especially the U.S. military, would be years ahead of private industry in its distribution and availability of standards? George Alspaugh -- Forwarded by George Alspaugh/Lex/Lexmark on 10/01/99 11:05 AM --- George: That world exists. It's called the United States' Military Standards. They are free. they are not copyrighted, so you can copy and distribute them. They are available over the internet. They were meant to be used, not to promote some hidden agenda. Best of all, they are clear, concise, and written in REAL ENGLISH, not some incomprehensible third-rate translation. check out: http://www.dodssp.daps.mil/ Also the FCC rules are not copyrighted etc. We may complain about our government, but you gotta love them once you see how screwed up other countries are. At 10:18 AM 9/30/1999 -0400, you wrote: Most of the world entered the information some decades ago. The greatest leap forward has been the advent of the internet. I need not elaborate on how quickly one can get information on almost any topic at their workstation via the internet. Sadly, the world of standards is stuck in the 1950's. Months or years go by to get consensus on new versions. Those who need them most must place orders for precious hard copies of new standards at exhorbitant prices. I can see why commercial books will always cost something, as they represent creative intellectual property that are made available by the the author/ publisher for profit. However, why would international standards bodies, which are not for profit, make it so difficult and expensive to acquire documents that make products safer for everyone? Imagine a world where.. - Every user of standards had a PC workstation - There was a world-wide internet to distribute information - International standards bodies maintained a website of standards - All standards contained hyper-links to related standards - Subscription to access these standards was free - Or, each subscriber (manufacturer) paid a modest fee per year for access Well, we are part way there.. George Alspaugh Lexmark International Inc. - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RESUMES JOB LISTINGS
Group, As a free service, we are now posting resumes and job openings in our EMC SUPPLIERS DIRECTORY: http://www.tempest-inc.com/suppliers.htm If you are looking for EMC people or looking for a job, email your resume or job announcement to us and we will post it at no charge. We already have some good ones, so take a look! regards, Lou Gnecco - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
hp 141T's
Group: A comment on the old hp 141T series of spectrum analyzers, that someone (probably someone like me) recently suggested: We have some and I like them, BUT: a) They are no longer supported by hp and some of the parts are no longer even available. b) If you are going to get one, you'd better be willing to spend a lot of time getting very familiar with the manual and learning how to repair and align it yourself. It will be hard to find someone that is competent to work on it. c) Treat it carefully. Old equipment can last a long time, or it can break down tomorrow, depending on how it was used or abused before you got it. With these, it is specially easy to blow the mixer or the front end. A lot of the idiot proofing safeguards that are built into modern computerized equipment, (and that we now take for granted) do not exist in the old stuff. d) Know who you are dealing with. Old equipment like this comes with either NO WARRANTY or 30 days at most. You could easily end up with an expensive door stop. Try explaining that to your boss after bragging about how much money you just saved! e) If you are outside the US, forget about it. You will have a hard time getting it into your country. There is no CE mark on this equipment, and never will be. f) If I were working for the government or for a big company, I wouldn't get one of these at all. It would be too hard to justify it to the many layers of non technical people that get involved, specially later, when you have to spend twice what it cost to get it fixed. Sometimes this actually makes sense with old sequipment, but you'll never be able to explain that to the bean counters! :) I would only get one if I worked for a small company with an understanding boss that had a lot of money and a real love of equipment. Also a sense of humor. Regards, Lou - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: Product Safety Semantics
Vitaly, Actually it is the other way around. As a former bureaucrat, must is definitely clearer. In the US government, when something is mandatory, the term is WILL as in: the distance will be at least three meters etc. (SEE MIL STD 461) One of the reasons that that the european standards are so vague and confusing is because they have been translated very badly. For example, the phrase Harmonized Standard did not exist in the english language before the european union came around. A better translation would have been standardized specification. In english, Harmonize is something you only do in music. I was raised bilingual, and I have done a lot of translations. I have found that one of the worst things a translator can do is to try to translate one word at a time, like machine translations do. What comes out may be english but it is often stilted and incomprehensible. Some words just dont translate. The Inuit (eskimos) for example, have seven different words for snow. lou At 12:27 PM 7/19/99 -0700, you wrote: I can't help making this innocuous comment. (English is not my major.) All I have to say is that Europeans are, as usually, more attached to purified English. Shall is stronger (more dictatorial or, if you want, directive) than must. -Original Message- From:John Juhasz [SMTP:jjuh...@fiberoptions.com] Sent:Monday, July 19, 1999 7:18 AM To: emc-p...@majordomo.ieee.org Subject: RE: Product Safety Semantics Many thanks to those who responded to my query about the use/meanings of the words 'shall' and 'must' in product safety standards. Must and shall appear to be interchangeable. UL1950 uses both (couldn't make up there minds?), but 'must' appears a lot in the Annexes. EN60950 (IEC950) uses 'shall' consistently. From the responses I got, 'will' is thrown in for good measure. Therefore, shall, must, and will mean 'mandatory'. 'Should' is a recommendation. I must, shall, will remember this. John A. Juhasz Product Qualification Compliance Engr. Fiber Options, Inc. 80 Orville Dr. Suite 102 Bohemia, NY 11716 USA Tel: 516-567-8320 ext. 324 Fax: 516-567-8322 - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: NEAR/ FAR FIELD CORRELATION ISSUES
Arun: I heartily agree with everything you said. Well done! It will not be easy to sell this idea to the emc world. When the standards are vague, acane and constantly-changing, and when it is unnecessarily expensive to set up and perform a test, this constitutes what is known in business as a Barrier To Entry that is, a way to artificially limit competition. Test laboratories (like us, for example) can charge more money when there are barriers to entry. People who make special instruments and antennas for EMC testing (like us) would lose out if there were fewer barriers to entry. Also people who install test shielded rooms, etc. There are substantial entrenched interests whose rice bowls would be threatened if emc became something anyone could do. I personally believe that the process can and should be simplified. It would help the manufacturers, who are the ones that really drive the economy. It would specially help small manufacturers. Like us. Lou At 11:18 AM 6/17/99 +1000, you wrote: Greetings and Salutations! I was wondering if this could be mailed out via the epc-pstc channels. I want to know if anyone is doing any work in near/ far field correlation to commercial EMC standard limits area and possibly correspond with them with a view to exchanging notes. Brief Follows: Brief: Application of Near Field and possibly Surface probe techniques in Evaluating Emissions from source equipment and correlating/quantifying this data to an OATS, LISN, Absorbing Clamp etc based measurement.. Details: We assume that the current EMC compliance regime around the world has quantified limits of compliance to which if every source equipment adheres to, then it has a reasonable chance of performing as intended in a real life situation, noting that the immunity threshold test levels are much more stringent than EM emission limits. Current EMC measurements are very cumbersome, require large expense in setting up and maintaining (calibrating) OATS, LISNS, Absorbing Clamps, Ferrite tiled lined semi- anechoics etc. Despite this expense, the measurement uncertainities are still of the order of 6 to 10dB (inherent). Every newly released EMC standard by IEC CISPR or CENELEC has potentially new transducers and new headaches from point of view of sourcing and maintenance, calibration. EMC today is where Safety was 10 years ago. I am of the opinion that EMC testing should be simplified and reasonably accessible to all end users. Continued progress and urban development has led to increasing levels of broad and narrowband noise to the extent that ambient profiles sometimes swamp out the limits; this has led to most test houses in the EU to opt for GTEMS or semi-anechoics (referred to as alternative all weather test sites) at considerable expense. Current techniques such as emission E Field prescanning in shielded rooms prior to OATS based testing with biconilog antennae have the drawbacks of peaking the emissions and reflections/standing waves. Hence: I propose to develop near or surface probe H (inverse of E) field techniques which actually senses the emission profiles and correlate them to an Absorber clamp, or OATS or LISN (Common mode fix) or whatever. Cables, panels, slots etc could be sniffed with a Loop and if it is possible to correlate this near or induction field data to compliance limits then it becomes very easy for individuals and organisations to do precertification. Transducers could be simple and light weight, rugged, and physically defined so that minimal calibration is required. EMI receivers will still need calibration. With these techniques, you measure actually what comes off the source and not the peak value of the bounced and direct rays within say the Fresnel ellipse, or move the Absorbing clamp up and down the rail and peak the field. Conducted emissions could be scanned by common mode techniques and radiated emissions by surface or near scans. Currently, these techniques are used only qualitatively for precompliance at board levels and more work needs to be done to bring them of age and reliability. (Am I right?) What I am proposing has a corollary with the bulk current or damped sinusoid (NEMP- Nuclear EM Pulsing) or lightning injection techniques (CS 114, 115 and 116 of 462D). With these methods, it was possible to achieve identical or several orders of magnitudes higher levels of RF injection power at a fraction of the cost of say an RS03 OR RS05(at least for the bulk cable loom!). What resulted was a cheap, powerful and a more repeatable test. Arun Kaore EMC Engineer ADI Limited Systems Group Test Evaluation Centre Forrester Road, St Marys, NSW 2760 P O Box: 315, St Marys NSW 1790 Tel: 61 2 9673 8375 Fax: 61 2 9673 8321 Email: kao...@sg.adi-limited.com.au - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line:
Re: Phase cancellation
Cortland, That makes sense to me. I think it will be easier to sell on a case by case basis at first. If the fcc made it part of the rules right away, they would have to deal with all the people who will now try it for the first time in their lives. If you, for instance, did a test like that, then you wrote it up carefully and you answered all their questions or even did a demo, they would probably buy it ( after trying it themselves, and having a lot of fun doing it too!) I have found them to be pretty competent and reasonable. Evaluating a lot of reports like yours on a case-by-case basis, they will find that some will get it right, some will be way off, and some will get some free coaching. Eventually most people will get the hang of it. When it stops being new and controversial, and becomes a tried-and-true ho-hum technique, it will become part of the rules. If I were trying to sell this technique, I would definitely get at least one or two FCC approvals under my belt first. Customers will inevitably ask: has the FCC bought this yet? Smart customers won't even ask the salesman. they'll ask the fcc. Best Regards, Lou At 04:00 PM 5/9/99 -0400, you wrote: Lou, It turns out not to be that critical. The ambient generator is a LOT further away, so about all that changes is amplitude. And often you don't need _complete_ cancellation, just 10 or 20 dB. Example: broadband noise from a nearby TV video signal can mess up a front-end. Cutting it 10 dB is often all it takes to be able to see below the limit. Tedious? Yes. But if one must measure emissions in the presence of on-frequency or nearby ambients, then tedious is the BEST we can do! And if SA with the system installed meets their requirement, the FCC could approve it. Just has to be demonstrated to the Commission's satisfaction. Not trivial! Cheers, Cortland == Original Message Follows Date: 08-May-99 06:39:18 MsgID: 1068-10160 ToID: 72146,373 From: Lou Gnecco INTERNET:l...@tempest-inc.com Subj: Re: Phase cancellation Chrg: $0.00 Imp: Norm Sens: StdReceipt: NoParts: 1 Cortland: I wonder how well that cancellation system works as you move the receive antenna up and down the hoist, and as you rotate its polarization. You would have to re-adjust the cancellation system every step of the way. This sounds like a lot of work. It would be simpler to run the test at night or on a weekend when the most troublesome ambients are usually down. If you don't keep tweaking it just right, it seems to me that the cancelling signal could actually make the problem worse. A system like this makes testing much more complicated. When you make a test more complicated, the probability of human error goes way up. I think you are going to have to wait a long time for the FCC to buy off on this, if ever, and as for the europeans? forget it! Lou At 11:19 PM 5/7/99 -0400, you wrote: We had the benefit of a fairly simple, flat environment, both at the (now closed) Fountain Valley location and the main OATS in Irvine. It was possible to put a bicon in an area where almost every ambient could be canceled, but tedious in the extreme, because the location was peculiar to each ambient. Using a delay line and variable gain/attenuation, and careful siting of the ambient antenna, seems to me appropriate for _most_ OATS except those in hilly country - and those generally are there because of the low ambients. by the way, this is NOT a new idea; indeed, I believe there have been Papers in the IEEE EMC Proceedings on this kind of a a setup. The stumbling block seems to have been FCC reluctance to approve a non-standard setup. But if SA were taken with an ambient canceler going, it seems to me that would effectively demonstrate equivalence. Cortland Cortland == Original Message Follows Date: 07-May-99 10:05:24 MsgID: 1068-8273 ToID: 72146,373 From: Brent DeWitt INTERNET:bdew...@ix.netcom.com Subj: Phase cancellation Chrg: $0.00 Imp: Norm Sens: StdReceipt: NoParts: 1 I have also played with phase cancellation, and found one very serious limitation, multipath. Unless you are out in a situation where the ambients look pretty much like point sources, you will be limited in the depth of the null that you can create, since you can only cancel one phase front with one reference antenna. Since many folks build sites in the hills, mountains or gullies to try to avoid ambients, this puts the site in a worst case location for using phase cancellation. Maybe in Topeka. Best regards, Brent DeWitt == End of Original Message = - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help
Re: Phase cancellation
Cortland: I wonder how well that cancellation system works as you move the receive antenna up and down the hoist, and as you rotate its polarization. You would have to re-adjust the cancellation system every step of the way. This sounds like a lot of work. It would be simpler to run the test at night or on a weekend when the most troublesome ambients are usually down. If you don't keep tweaking it just right, it seems to me that the cancelling signal could actually make the problem worse. A system like this makes testing much more complicated. When you make a test more complicated, the probability of human error goes way up. I think you are going to have to wait a long time for the FCC to buy off on this, if ever, and as for the europeans? forget it! Lou At 11:19 PM 5/7/99 -0400, you wrote: We had the benefit of a fairly simple, flat environment, both at the (now closed) Fountain Valley location and the main OATS in Irvine. It was possible to put a bicon in an area where almost every ambient could be canceled, but tedious in the extreme, because the location was peculiar to each ambient. Using a delay line and variable gain/attenuation, and careful siting of the ambient antenna, seems to me appropriate for _most_ OATS except those in hilly country - and those generally are there because of the low ambients. by the way, this is NOT a new idea; indeed, I believe there have been Papers in the IEEE EMC Proceedings on this kind of a a setup. The stumbling block seems to have been FCC reluctance to approve a non-standard setup. But if SA were taken with an ambient canceler going, it seems to me that would effectively demonstrate equivalence. Cortland Cortland == Original Message Follows Date: 07-May-99 10:05:24 MsgID: 1068-8273 ToID: 72146,373 From: Brent DeWitt INTERNET:bdew...@ix.netcom.com Subj: Phase cancellation Chrg: $0.00 Imp: Norm Sens: StdReceipt: NoParts: 1 I have also played with phase cancellation, and found one very serious limitation, multipath. Unless you are out in a situation where the ambients look pretty much like point sources, you will be limited in the depth of the null that you can create, since you can only cancel one phase front with one reference antenna. Since many folks build sites in the hills, mountains or gullies to try to avoid ambients, this puts the site in a worst case location for using phase cancellation. Maybe in Topeka. Best regards, Brent DeWitt == End of Original Message = - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: EMC Books
Mr. Montrose is basically one of our competitors, but I have to say that his articles have been excellent. Lou At 07:39 AM 5/7/99 -0600, you wrote: In all fairness, I have this book and have also taken the class from Mr. Mark Montrose. I found the class extremely interesting and very useful. Rick Busche -Original Message- From: Qu Pingyu [mailto:pin...@ime.org.sg] Sent: Thursday, May 06, 1999 6:49 PM To: 'b...@namg.us.anritsu.com' Cc: emc-p...@ieee.org Subject:RE: EMC Books Barry: I don't think the 1996 version of Montrose's book is good. Though there are many useful design rules listed, the reason behind is not explained very clearly. I also attended a course on PCB EMC design conducted by Mr. Montrose himself and I have to say I was quite disappointed. I second your recommendation for the second and third book listed on the wegb page (I havn't read the first one I would like to), plus Paul's Introduction to EMC. Regards Qu Pingyu -Original Message- From: b...@namg.us.anritsu.com [SMTP:b...@namg.us.anritsu.com] Sent: Friday, 7 May 1999 0:20 To: smtp@WILTRON7@Servers[\Jon D. Curtis\ j...@curtis-straus.com]@namg.us.anritsu.com Cc: emc-p...@ieee.org Subject: Re: EMC Books Jon, I just visited your book store. Very pertinent comments on each book although brief. The first three books should be listed must read for EMC engineers. Suggestion for the book of Printed Circuit Board Design Techniques for EMC Compliance, Mark I. Montrose, 1996: The newest edition seems to be 1998? The new edition added much more materials on Signal Integrity. Barry - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: EMC Resources on the web
Randall: Please be sure to include our web site: http://www.tempest-inc.com and specially our EMC SUPPLIERS DIRECTORY: http://www.tempest-inc.com/suppliers.htm Listing in our directory is absolutely free, so it is a very complete one. We would like to build it up into the most complete definitive EMC directory in the world. We set up this site as a service to our clients, who are always asking where can I get conductive gaskets, who makes microwave absorbing material etc. This used to require us to do some research and then write a letter. Now we just say Check our suppliers directory. Lou At 05:00 PM 5/5/99 -0700, you wrote: Hello! Greetings from Orange County! I am interested in compiling a list of valuable EMC related resources available on the web. If you kind guys and gals out there could address them to me, I will compile the results and post them for the group all at once. Thanks! -- Sincerely, Randall T. Flinders EMC Engineer Emulex Network Systems V: (714) 513-8012 F: (714) 513-8265 randall.flind...@emulex.com __ __ __\ /__ __/ \__ E M U L E X Chairman Orange County Chapter IEEE EMC Society r.flind...@ieee.org Attachment Converted: C:\NETEMP\EMCResou - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: Precompliance Testing
Jim, the noun for one who shleps is also shlep I don't know why, but as one who grew up in new york city, i can assure you that this is so. that is why you wont find shlepper maybe for the same reason that the plural for bagel is also bagel 1 bagel, 2 bagel, N bagel ( lim as n- infinity) why does this come under precompliance testing? because we'll all agree that the certification process is a shlep. Lou - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: Precompliance Testing
It's always a good idea to get a spectrum analyzer some antennas and do a site survey before you build either the OATS or the shielded room. Knowing what the ambients are in advance can save you a lot of trouble and money in both cases. It makes sense, but hardly anyone does it. why? because they tend to think of the shielded room as part of the build out i.e. as office space, instead of as what it really is: an electronic instrument. like an antenna. Lou At 12:22 PM 5/5/99 -0700, you wrote: I second that opinion. My experience shows SEVERE ambient issues with rooftop sites. -- Sincerely, Randall T. Flinders EMC Engineer Emulex Network Systems V: (714) 513-8012 F: (714) 513-8265 randall.flind...@emulex.com __ __ __\ /__ __/ \__ E M U L E X Chairman Orange County Chapter IEEE EMC Society r.flind...@ieee.org -- From: Hans Mellberg Sent: Wednesday, May 05, 1999 7:59 AM To:emc-p...@majordomo.ieee.org; bogda...@pacbell.net; Gary McInturff Cc:'Brent DeWitt'; Allen Tudor; emc-p...@ieee.org Subject: Re: Precompliance Testing Before you put a rooftop OATS, (assuming you are not located in Easter Island or the Caribean Islands!) you are going to deal with substantially higher ambient signals. It so happens that when you need a stronger signal, a common practice is to raise the antenna! I have battled those problems twice in my past and I would not reccomend rooftop OATS anymore. --- bogda...@pacbell.net wrote: May I add a note of caution: It may be worthwhile to check the permissible loading of the roof, especially when you are in the Southwest where roofs are mostly for shade and a few drops of rain. I guess that you don't want to appear suddenly in the conference room below Bogdan. Gary McInturff wrote: I'll agree with Brent, and others, the headaches of a metal room or the metal studs et al, in a building are going to make you pull your hair out. But there is an alternative to the parking lot. You may want to consider the roof. The ground reference can be put up there as well, especially if you are doing pre-compliance stuff. You don't have to give up parking space - which is sure to irate somebody. The roof gets a little hot, but that only gives you the opportunity to work in your cutoffs, and showing up to a meeting with the suits dressed like this is always good for a laugh! Gary snip === Best Regards Hans Mellberg EMC Consultant _ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). Attachment Converted: C:\NETEMP\REPrecom - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: Precompliance Testing
Jim: Shlep is a Yiddish word (comes from German.) that has made its way into English. You dont have to be Jewish to use it, and it is very common in L.A. and in the northeast. It means to carry or haul around: as in something heavy, cumbersome of unpleasant. It also means to have to walk or travel a lot (in an unpleasant sense.) It is sometimes used as a noun, to indicate a long distance, or a guy that has to SHLEP: that is to do hard or unpleasant work, (for not much money.) as in: I have to SHLEP this spectrum analyzer in out of the van. I have to SHLEP all the way to the third floor just to use the bathroom. The bus stop is a five block SHLEP from here. That poor SHLEP just got assigned to the EMC group. Best Regards Lou Gnecco TEMPEST INC. HERNDON VIRGINIA (a native New Yorker) At 03:37 PM 5/3/99 -0700, you wrote: Ed, I'm not familiar with the verb to schlep. Is this a specialized technical term, perhaps particular to EMC or to the military arena? Jim Dr. Jim Knighten e-mail: jlknigh...@ieee.org mailto:jlknigh...@ieee.org Senior Consulting Engineer NCR 17095 Via del Campo San Diego, CA 92127http://www.ncr.com http://www.ncr.com Tel: 619-485-2537 Fax: 619-485-3788 -Original Message- From: ed.pr...@cubic.com [SMTP:ed.pr...@cubic.com] Sent: Monday, May 03, 1999 2:38 PM To: 'Brent DeWitt'; Allen Tudor; emc-p...@ieee.org; Gary McInturff Subject:RE: Precompliance Testing The roof alternative has been done more than a few times. Emaco (now part of TUVPS) in San Diego had a pair of pneumatic lifts which travelled from their second floor through the roof. The test specimen and antenna could be set up on their respective elevators, pushed up through the roof, and come to rest level with the roof ground plane. I imagine that they did have some problems with weathering of conductive interfaces and water leakage, but it did serve them well for a few years. BTW, I agree that the parking lot option is better than trying to live with a test site WITHIN a commercial office structure. There have been several posters who already described the problems found inside the building. Some of the problems with a parking lot site are: 1. Sometimes the cars encroach on the site. 2. You have to schlep all your stuff out to the site, and back again at night. 3. Sometimes, your utilities get mysteriously shut off, necessitating a call to your plant facilities guy (for a big company; for little companies, you get to look for the breaker yourself). 4. Flooding. 5. Wind can knock over your test antenna mast. Securing the mast each night adds another housekeeping task. 6. Sunburn. (If I'm gonna get sunburned, let it be with a yacht beneath my feet.) 7. Ants and rodents. (You are only one step short of a picnic.) 8. Snow. Ice. Wind chill factor. (Enough said.) Ed Ed From: Gary McInturff gmcintu...@packetengines.com Subject: RE: Precompliance Testing Date: Mon, 3 May 1999 12:11:30 -0700 To: 'Brent DeWitt' bdew...@ix.netcom.com, Allen Tudor allen_tu...@pairgain.com, emc-p...@ieee.org I'll agree with Brent, and others, the headaches of a metal room or the metal studs et al, in a building are going to make you pull your hair out. But there is an alternative to the parking lot. You may want to consider the roof. The ground reference can be put up there as well, especially if you are doing pre-compliance stuff. You don't have to give up parking space - which is sure to irate somebody. The roof gets a little hot, but that only gives you the opportunity to work in your cutoffs, and showing up to a meeting with the suits dressed like this is always good for a laugh! Gary -Original Message- From: Brent DeWitt [SMTP:bdew...@ix.netcom.com] Sent: Friday, April 23, 1999 7:12 PM To: Allen Tudor; emc-p...@ieee.org Subject:RE: Precompliance Testing Allen, From bunches of years of designing and using sites, what I would suggest is, IMHO, use the money to reserve a large space in the parking lot free of obstacles. Current construction techniques in buildings use lots of steel 2x4s for the walls and there will likely be steel in the floor above you. All of these contribute to resonances in the emissions measurements that are far too difficult to want to deal with. The best way to do radiated measurements is to be a minimalist. Get as far away from any structure as you can, put
Re: Rodents, part II
Brent, When i worked for NASA we also had water moccasins. They liked to get in the cable trays and snuggle up next to the RG-9 coax cables, which were indistinguishable from them. Those snakes were highly poisonous and very aggressive. They were also BIG. they could strike clear across the ( 1 lane) road, and if you threw rocks at them, they would actually chase you. If you ever run into this problem, one way to get them is with a CO2 fire extiguisher. they hate the cold and it drives them off. Another way is to take a 10 ft piece of conduit, run a length of RG-223 thru it, leaving a loop at the far end. Then you ease up to the snake, slip the loop over its head and PULL, decapitating it. This takes nerve, because to do this you must be well within the snake's striking distance. I never did it, but I have stood there (aghast) and watched one of our technicians do it, several times. Do not try this at home. Lou At 03:47 PM 5/3/99 -0600, you wrote: Has anyone else noticed how rodents (Prairie dogs, squirrels, etc.) just _love_ polyethylene? They must think it's candy. Prairie dogs have chewed all the way to the center conductor of the coax at a couple of sites I've run and back in my Forest Service radio tech days we had to use C wire impregnated with a chemical that made it taste bad to the squirrels or they would chew it up. Sorta EMC related... Brent -Original Message- From: ed.pr...@cubic.com [mailto:ed.pr...@cubic.com] snip 7. Ants and rodents. (You are only one step short of a picnic.) Ed - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
european community meeting
Group: Yesterday the US Dept of Commerce held a meeting regarding the EMC annex of a Mutual Recognition Agreement being worked out between the US and the european union. The idea is to work out procedures where american emc labs will be recognized by the europeans as full-fledged competent bodies. that is, to give us the same status the european emc labs. Before we all jump for joy, this looks like the first step towards replacing our FCC rules with the vague, arcane amd constantly changing european standards. This would enrich the emc labs (like us) but would put a big burden on all manufacturers, specially small businesses. I think that in the long run this would be very bad for our economy. Anyway, I went to the meeting brought back about 50 pages of handouts, with some interesting stats. For example: last year the Germans failed 44% of the domestic radio and tv sets they tested. They hit manufacturers with a total of 418,000 Marks in fines (about $200,000). This doesnt seem like much, until you figure that each european country is about as big as one of our states. multiply by 50. There is too much material to post on our web site. If any one is interested, Ill send you a copy for the cost of printing and postage. $10 ought to do it. Send to TEMPEST INC. 11654 PLAZA AMERICA DRIVE, RESTON VA 20190 Note: we are doing this as a service to the group. This is not a commercial, so please don't dump us off the reflector (again) Rich! ;) Regards, Lou - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
shielded room courses
Group, The Armed Forces Communications-Electronics Association (AFCEA) has some great courses on building, moving, testing, and managing shielded rooms. Call Ann Beckham at 703-631-6100 for a flyer. These courses are unclassified, so any one can attend. The instructor is very personable, knowlegeable, and an all-around great guy. (I teach it.) Lou. - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Load inductor
Kim, Try Caddell-Burns in new york. Look under filters in our EMC suppliers directory: http://www.tempest-inc.com/suppliers.htm Lou At 11:43 AM 4/20/99 +0200, you wrote: Hi groupe I'm tryimg to find an inductor for load test of a LAN circuit (10/100Base UTP). Do anyone know a manufacturer of 1% 220uH and 180uH inductors with the following specifications: Rparallel 2Kohm, Rserial 0.5 ohm and Cparallel = 12pF +-20% Best regards, Mr. Kim Bol Jensen i-data, Denmark - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Excessive smoke
Group: Here is a typical example of what is wrong with those european standards. Question: If you bought a TV set, turned it on, and it started to smoke, wouldn't you consider that a failure? I dont know what they do in europe, but here in america we would return it and get our money back. Lou At 12:06 AM 4/17/99 +0300, you wrote: Dear Jeff, If a product smokes after an abnormal test it is not considered a failure. If the smoke was from an electrolytic capacitor, some test agencies might ask you to submit a declaration fom the capacitor manufacturer that the elecrolyte is not toxic. In regards to SEMI, if a product smoked after an abnormal test, it is also not considered a failure. Best Regards, I'm full of questions this week. Here's today's. If a component abnormal test generates excessive and sustained smoke (several minutes), but does'nt breach reinforced or double insulation, nor emit flame from the enclosure, is it considered a failure? Intuitively, it seems like it would be, because of toxicity, but I have been unable to find anything in the safety standards to support this. I have checked EN 60950, EN 50178, UL 1012, and CSA C22.2 No. 107.1. By the way, this product could be used in clean room applications. I am familiar with Semi S2, but it is unclear as to the degree of smoke allowed. Section 19.1 says, The use of combustible and smoke-generating materials in the construction of the process equipment should be limited. In this case, it was a PCB that smoked. Thanks. Jeff Jenkins Senior Regulatory Compliance Engineer Advanced Energy Industries, Inc. Fort Collins, CO USA 80525 Opinions are my own and not necessarily shared by Advanced Energy Industries, Inc. or its affiliates. - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). PETER S. MERGUERIAN MANAGING DIRECTOR PRODUCT TESTING DIVISION I.T.L. (PRODUCT TESTING) LTD. HACHAROSHET 26, P.O.B. 211 OR YEHUDA 60251, ISRAEL TEL: 972-3-5339022 FAX: 972-3-5339019 E-MAIL: pe...@itl.co.il Visit our Website: http://www.itl.co.il - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Official Answers
Richard, The Headquarters of the European Commission is here in Washington DC, it is easy to get to during the day, with plenty of parking on the street. The people there are pretty helpful will give you free copies of the right documents like 89-336 EEC ( documents that some services charge $100 for). Other than that, we have an arrangement with a European EMC lab which is certified as a competent body. We picked one which is not over here in the US trying to hustle american businesses. Whenever we have a question about the vague, arcane and constantly-changing european emc standards, we get their official opinion (in writing.) On April 27, there will be a meeting here in washington dc to discuss ways of certifying US labs like ours (and yours) as european competent bodies. This sounds like a great idea until you realize that it is the first step towards imposing their rules on all equipment sold in the United States. This will be great - in the short run - for us testing labs, but in the long run it will destroy small businesses and hurt our economy. In the long run, if this goes through we will end up like europe: with 20% unemployment. Lou At 11:52 AM 4/15/99 -0400, you wrote: If one has a question on an EU Directive, is there a means for obtaining an official answer? - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Need Ferrite bead Spice models
Harry: Check out westbay emc software. We use it. for a description and free downloads see: http://www.tempest-inc.com/software.htm Lou At 10:51 AM 4/8/99 -0700, you wrote: Where can I get ferrite bead SPICE models in the 1Mhz to 100Mhz range. I desire something simple that can simulate DC current filters with a SPICE transient response. If it could simulate both resistance and reactance as a function of frequency at varying DC current levels that would be sweet. I am open to any ideas. thanks Harry Dellamano consultant T D Systems !DOCTYPE HTML PUBLIC -//W3C//DTD HTML 4.0 Transitional//EN HTMLHEAD META content=text/html; charset=iso-8859-1 http-equiv=Content-Type META content=MSHTML 5.00.2014.210 name=GENERATOR STYLE/STYLE /HEAD BODY bgColor=#ff DIVFONT size=2nbsp; Where can I get ferrite bead SPICE models in the 1Mhz to 100Mhz range. I desire something simple that can simulate DC current filters with anbsp;SPICE transient response. If it could simulate both resistance and reactance as a function of frequencynbsp;atnbsp;varying DC current levels that would be sweet. I am open to any ideas./FONT/DIV DIVnbsp;/DIV DIVFONT size=2thanks/FONT/DIV DIVFONT size=2Harry Dellamano/FONT/DIV DIVFONT size=2consultant/FONT/DIV DIVFONT size=2T D Systems/FONT/DIV/BODY/HTML - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Power Inductor for Power Supply Design
Ravinder: Try caddell-burns in New York Also check our supppliers directory: http://www.tempest-inc.com/suppliers.htm Lou At 03:22 PM 4/2/99 -0700, you wrote: Hi, I am looking for a 10 uH power inductor for a power supply design, with minimum 3 A current rating. The critical requirement is that the Z-height should be less than 3 mm. I have looked at the catalogs of TDK, Coilcraft, Coiltronics, etc. was unable to find one. Does anyone know of a vendor who makes power inductors with these specifications. Regards, Ravinder Email: ajm...@us.ibm.com *** Always do right. This will gratify some people and astonish the rest. Mark Twain - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Manufacturer of reference discones?
Kevin: Check under Antennas in our suppliers directory: http://www.tempest-inc.com/suppliers.htm Lou At 05:19 PM 3/26/99 +0200, you wrote: Hello Everyone, I am looking for a manufacturer who supplies a reference discone for measurements in the GSM bands. Could someone please send me any contact info? Many thanks, Kevin Williams ps: Any South African companies perhaps? -- --- Dr Kevin Williams, MIEEE Electromagnetic Software and Systems (EMSS) Stellenbosch, South Africa [http://emss.co.za] Tel/Fax: +27 21 880-1880/+27 21 880-1880/1727 ---Cont ent-Type: text/x-vcard; charset=us-ascii; name=williams.vcf Content-Transfer-Encoding: 7bit Content-Description: Card for Kevin Williams Content-Disposition: attachment; filename=williams.vcf Attachment Converted: C:\NETEMP\williams.vcf - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Building Main Transformer causes Video Problems
John, We occasionally solve wiggly monitor problems for customers in the washingotn dc area. If he is adjacent to a power transformer, and his tv is wiggling, he is probably getting about 300 milligauss of magnetic field strength. This is a lot, and would not be advisable for a pregnant woman, for example. 13 milligauss is typical for an urban area, 2 milligauss for a rural area. I wouldnt want to sit there. Lou At 03:43 PM 3/22/99 -0500, you wrote: Hello Group, A friend of mine called and asked if I knew anything about the interaction of his building's main power transformer and interference seen on his pc monitor. He sits adjacent to the transformer that is in a utility room behind the wall of his lab. He sees the video distorted and was wondering about any health risks. I've seen articles on this subject over the years; mostly about high power lines in residential areas. Does anyone have facts or a pointer to information on this type of interference? Is there a health risk? Thanks - John (this is not an employer related inquiry) - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Spare Change
Ed, Good work. Thanks! you have answered a lot of questions, but get this: The spectrum that you measured is not just a function of the emission from the baggies, it is also a function of your antenna, which was cut for 300 MHz. The fact that you still had a 35 dB signal to noise ratio at 1 GHz shows that the emissions are powerful and broadband. One of us needs to do it with a broadband antenna. I have been pretty busy, but we have all the right equipment, a nice anechoic chamber etc. Maybe this weekend. Plus, I dont have a boss that's going to yell at me for fooling around in the lab. I OWN the lab. (yes, it IS nice!) Regards, Lou Return-Path: owner-emc-p...@majordomo.ieee.org From: ed.pr...@cubic.com Date: Thu, 18 Mar 1999 14:59:33 -0800 Subject: Spare Change To: EMC-PSTC emc-p...@majordomo.ieee.org Sender: owner-emc-p...@majordomo.ieee.org Reply-To: ed.pr...@cubic.com X-Resent-To: Multiple Recipients emc-p...@majordomo.ieee.org X-Listname: emc-pstc X-Info: Help requests to emc-pstc-requ...@majordomo.ieee.org X-Info: [Un]Subscribe requests to majord...@majordomo.ieee.org X-Moderator-Address: emc-pstc-appro...@majordomo.ieee.org The Coins-in-a-bag thread has been moving from anecdote to anecdote for the past week or so. Let's take this to the next level---sloppy field testing! This morning, I procured two fresh, new 1 gallon size Baggies brand plastic food storage bags, a single Baggies brand sandwich storage bag, and $3.06 (6 cents, 7 nickels, 4 dimes and 9 quarters) in clean US currency. I cut a whip antenna to 25 cm length (banana/BNC adapter included), yielding a 1/4 wave antenna for roughly 300 MHz. I then used this whip as a monopole antenna connected first to my Tektronix TDS 640A oscilloscope (1 GHz real-time BW) and then to my HP-8562A spectrum analyzer. I placed the coins into one of the 1 gallon bags, and inflated it with a swooping motion through the air (my breath has high humidity). I held the bag only by the neck, trapping the air and causing the bag walls to bulge, approximating a 10 diameter sphere. I then vigorously shook the bag, at about 12 in front of the whip antenna, while observing the displays. ++ TEST RESULTS Oscilloscope, 5uS/div, 1 V/div Test 1: 2.46 Vpeak, with an exponential decay lasting over 45 microseconds and a TC of about 25 microseconds. The risetime is about 136 nanoseconds. A view of the acquired waveform and an expanded risetime view is attached as Coins.zip. Test 2: 2.64 Vpeak, similar decays. This has an interesting double discharge at the leading edge. An initial discharge triggers the scope, then another discharge hits about 500 nanoseconds later. A view of the acquired waveform and an expanded risetime view is attached as Coins.zip. Note: It only takes a few shakes to get a decently high discharge. And now, on to the spectrum analyzer. Similar test distance and conditions. Using a 1 MHz resolution bandwidth, a 1 MHz video bandwidth, 0 Hz span width, 0 dB of RF attenuation and peak hold trace. Test 3: 10 MHz 31 dBuV noise floor 59 dBuV transient noise peaks Test 4: 100 MHz 31 dBuV noise floor 62 dBuV transient noise peaks Test 5: 500 MHz 31 dBuV noise floor 70 dBuV transient noise peaks Test 6: 1 GHz 31 dBuV noise floor 66 dBuV transient noise peaks Test 7: 5 GHz 31 dBuV noise floor 50 dBuV transient noise peaks Test 8: 10 GHz 35 dBuV noise floor 40 dBuV transient noise peaks Test 9: 15 GHz 43 dBuV noise floor 47 dBuV transient noise peaks Test 10: 500 MHz 31 dBuV noise floor 70 dBuV transient noise peaks Note: I removed all coins except the 6 cents. Test 11: 500 MHz 31 dBuV noise floor 70 dBuV transient noise peaks Note: I removed all coins except the 7 nickels. Test 12: 500 MHz 31 dBuV noise floor 70 dBuV transient noise peaks Note: I removed all coins except the 9 quarters. Test 13: 500 MHz 31 dBuV noise floor 70 dBuV transient noise peaks Note: All coins back in the bag. Test 14: 500 MHz 31 dBuV noise floor 61 dBuV transient noise peaks Note: All coins back in the small sandwich size bag. (Maybe less vigorous shaking.) Test 15: 1 GHz 31 dBuV noise floor 53 dBuV transient noise peaks Note: All coins back into the gallon bag. I exhaled into the bag several times, causing visible condensation on coins and bag walls. The observed transients were far fewer numerically, and of lower magnitude. What this seems to show is: 1. There are measurable emissions present across the spectrum from 10 MHz to 15 GHz. 2. The emissions clearly stand out from the ambient noise level of an open industrial area. 3. It is easy to create several volts into a high impedance load. 4. The generated levels do not depend on
Re: explanation of ESD events with coins in baggie.
Do you get the same effect with the coins in a cloth bag or a paper bag? Has anybody tried it? Lou At 10:57 AM 3/15/99 -0600, you wrote: Douglas, I have seen similar events in a different way. Years ago, I helped design an electronic system using plastic chassis with nickel surface plating. The system passed 15kv ESD air discharge and 8kv contact. But in the hardware lab, the system gets data error everytime a piece of metal (like a screw driver) is striked against the nickel plated surface on chassis. A digital scope is used to measure the noise generated on power and ground planes on the PCB inside the chassis and the scope captured a noise voltage as high as 8 volts peak to peak on the PCB from a few hundred MHz to beyond GHz. The PCB was very well decoupled with power next to ground planes and many on board capacitors. This puzzled me at first. But I remembered a very knowledgeable mechanical engineer once told me to never use nickel material in an application where friction takes place. Nickel has a very hard and rough surface, so in a frictional application, it always damages the mating surface. Maybe this explains the events that you saw, and the ESD generated by the metal surface was much higher than 15kv. Regards, George Tang Douglas McKean wrote: Hans, That's certainly an interesting explanation, but does not correlate to at least three different scenarios. 1) A calibrated ESD simulator in self discharge mode at 15KV. When the results of the ESD simulator are compared to the results of the coins, the coins have a fairly wideband constant level from 0 - 2 GHz. Both start off at roughly the same level with the only the coins remaining constant throughout. The ESD simulator has approx a -20dB per octave drop off. A side interest is that on the display of the SA has an IF overload indication. This tells me that the transients from the coins are quite possibly a lot higher and much quicker than what the SA can handle within the sampling window. 2) The level from the coins is proportional to the dissimilarity of the metals of the coins. A bag of quarters has a lower profile than a bag of quarters and pennies. Thus, there is some function due to electronegativity differentials. Actually, a significant amount of difference. 3) I can cause the same effect by sliding the coins back and forth as a group within the bag. Thus, the coins are in at least incidental contact with each other so that differing potentials amongst the coins is minor. I'm not sure if anyone knows the reason. Regards, Doug McKean At 11:11 AM 3/11/99 -0800, Hans Mellberg wrote: There is an expanation for this seemingly unlikely event. Having coins in a baggie and jingeling them causes the following events to occur: The rubbing of a coin against the polymer causes triboelectric charging of both the coin and localized areas of the bag. Since there are multiple coins, each coin will charge at some voltage level but not necessarily the same as another coin. When two coins of different charged voltages come within dielectric breakdown distances, a discharge will occur from one coin to the other in order to equalize the charge distribution (q1=C1V1 and q2=C2V2. When they touch, the new q1 will be C1V3 and q2= C2V3 where V3=(q1+q2)/(C1+C2)). Since coins are electrically small with very small capacitances, the expected discharge waveform has a very fast risetime hence the radiation at the GHz region. There will also be discharges from the localized charged areas of the polymer to coins of different voltages. While separating two charged surfaces from each other, the voltage rises significantly since the capacitance is being reduced and the conservation of charge must be preserved which is the basis for tribolectric voltage generation. Hope that helps Hans Mellberg ---b...@namg.us.anritsu.com wrote: Hi Douglas, What you described is very interesting! But I cannot understand Jingling change in a ziplock bag produces very high levels of super fast transients up into the GHz range. It seems to me that jingling coins, jangling keys, and slamming metal door would certainly produce acoustic waves. How come they also produced electromagnetic waves? If do, under what conditions? What is the mechanism to produce very high level of transient EM waves? Did that company incorporate those kinds of Jingling change in a ziplock bag tests into regular ESD tests for their thereafter products? What is the lessen we all should learn from this particular example? Hopefully you don't think it's offensive to ask above questions. I am just very curious. Thank you. Best Regards, Barry Ma (408)778-2000 x 4465 - Original Text From: Douglas McKean dmck...@corp.auspex.com, on 3/10/99 2:55 PM: At 08:03 AM 3/8/99 PST, Bailin Ma wrote: Hi
Re: MIL-STD-461D vs. EN55022
Amund: I think you have forgotten one aspect: the business aspect. The strict, arcane, and constantly changing european specs artificially create business for testing labs (like us). It is no coincidence that the specs were written by representatives of the European Laboratories. (God bless them! they have created plenty of business for us too.) They also make it very hard to build or sell anything in europe, or to start a new manufacturing business. There is a site on the internet that says EMC stands for Eliminate Minor Companies. If you monitor this excellent discussion group, you can see that there many,many questions about what does this european spec mean? The questions don't come from laymen. they come from PROFESSIONALS. When standards are that vauge, there is something seriously wrong. The crazy standards depress the european economy, and are one reason why you have 20% unemployment, while we only have 4%. That is one man's opinion, but we are making money from it, so I am NOT complaining! Regards, Lou At 08:56 AM 3/12/99 +0100, you wrote: Hello all ! I have compered the conducted emission limits for MIL-STD-461D (CE102) and EN55022. In the identical frequency range it seems that there is a gap of approximate 20dB between the limit lines. It was a surprise for me that EN55022 have lower limits than CE102, even though the EN55022 operates with average measurements. The test set-ups are not identical, but I feel it should not be significant since they use the same type of LISN. I have always had the feeling that all military limits were more severe that commercial standards. Are there any aspects that I have forgotten ? Regards Amund Westin - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: explanation of ESD events with coins in baggie.
Doug, Despite the sampling window, the spectrum analyzer has a wide open front end. It is easily saturated by broadband signals, even though you think you are only looking at say, 100 to 200 MHz, the front end amplifiers see everything. A lot of things have a piezoelectric effect, including bone and ice. Maybe you are seeing that? Whatever it is, it's broad band. You are seeing some extremely narrow impulses which have a wide range of frequency components. I have GOT to try this! Lou Hans, That's certainly an interesting explanation, but does not correlate to at least three different scenarios. 1) A calibrated ESD simulator in self discharge mode at 15KV. When the results of the ESD simulator are compared to the results of the coins, the coins have a fairly wideband constant level from 0 - 2 GHz. Both start off at roughly the same level with the only the coins remaining constant throughout. The ESD simulator has approx a -20dB per octave drop off. A side interest is that on the display of the SA has an IF overload indication. This tells me that the transients from the coins are quite possibly a lot higher and much quicker than what the SA can handle within the sampling window. 2) The level from the coins is proportional to the dissimilarity of the metals of the coins. A bag of quarters has a lower profile than a bag of quarters and pennies. Thus, there is some function due to electronegativity differentials. Actually, a significant amount of difference. 3) I can cause the same effect by sliding the coins back and forth as a group within the bag. Thus, the coins are in at least incidental contact with each other so that differing potentials amongst the coins is minor. I'm not sure if anyone knows the reason. Regards, Doug McKean At 11:11 AM 3/11/99 -0800, Hans Mellberg wrote: There is an expanation for this seemingly unlikely event. Having coins in a baggie and jingeling them causes the following events to occur: The rubbing of a coin against the polymer causes triboelectric charging of both the coin and localized areas of the bag. Since there are multiple coins, each coin will charge at some voltage level but not necessarily the same as another coin. When two coins of different charged voltages come within dielectric breakdown distances, a discharge will occur from one coin to the other in order to equalize the charge distribution (q1=C1V1 and q2=C2V2. When they touch, the new q1 will be C1V3 and q2= C2V3 where V3=(q1+q2)/(C1+C2)). Since coins are electrically small with very small capacitances, the expected discharge waveform has a very fast risetime hence the radiation at the GHz region. There will also be discharges from the localized charged areas of the polymer to coins of different voltages. While separating two charged surfaces from each other, the voltage rises significantly since the capacitance is being reduced and the conservation of charge must be preserved which is the basis for tribolectric voltage generation. Hope that helps Hans Mellberg ---b...@namg.us.anritsu.com wrote: Hi Douglas, What you described is very interesting! But I cannot understand Jingling change in a ziplock bag produces very high levels of super fast transients up into the GHz range. It seems to me that jingling coins, jangling keys, and slamming metal door would certainly produce acoustic waves. How come they also produced electromagnetic waves? If do, under what conditions? What is the mechanism to produce very high level of transient EM waves? Did that company incorporate those kinds of Jingling change in a ziplock bag tests into regular ESD tests for their thereafter products? What is the lessen we all should learn from this particular example? Hopefully you don't think it's offensive to ask above questions. I am just very curious. Thank you. Best Regards, Barry Ma (408)778-2000 x 4465 - Original Text From: Douglas McKean dmck...@corp.auspex.com, on 3/10/99 2:55 PM: At 08:03 AM 3/8/99 PST, Bailin Ma wrote: Hi Group, We have already seen awards for the most misleading ads, worst attire, worst films, . Why not awards for worst EMC and PS qualities? Barry Ma Morgan Hill, CA 95037 Long ago in another company, I was completing the testing for a large rack mounted device, i.e. emissions, immunity, safety, some parts of Bellcore. We got a call from one of our customers complaining about how sensitive our equipment was and how susceptible it was to ESD events during their own testing of our equipment. This was deemed unacceptable by them. This decision of theirs jeopardized a sale of several million dollars. The finger was duly pointed by everyone right to yours truly. My head was literally in no uncertain terms put on the block. I contested producing repeatable and acceptable ESD test
Re: Awards for Worst EMC/PS qualities
Ed, now THAT is a good one. it should win. It's not that unusual though. It happens quite often just like you said, specially the part about the VP getting promoted. The tester gets blamed if the room fails. They dont want you to find leaks, they want you to do something and then write a report saying that it passes. It's no joke though. When that classified data leaks out and runs down the hillside it can, and occasionally DOES, get someone's kid killed. If he or she is the right age and wearing a uniform, it might be YOUR kid. Lou At 08:59 AM 3/11/99 -0800, you wrote: Subject: Awards for Worst EMC/PS qualities Author: b...@namg.us.anritsu.com (Bailin Ma) at Internet Date:03/08/1999 8:03 AM Hi Group, We have already seen awards for the most misleading ads, worst attire, worst films, . Why not awards for worst EMC and PS qualities? Barry Ma Morgan Hill, CA 95037 OK, I'll submit just one more entry, even though this will need a new category (which I'll call Stupid Construction). Many years ago, a very large defense contractor decided that a black program needed multiple shielded enclosures within their SCIF so as to keep their classified data from leaking out and running down the hillside. So, the Program Manager talked to the Facilities Engineer, and together they said We can build our own TEMPEST shielded room. We will even do it cheaper and faster than any of these dumb quotes we have. So it came to be that they ordered much chicken wire, and beryllium copper fingerstock, and lumber, and drywall panels, and oh yes, very very many 2 long drywall screws. And a three phase powerline filter. And the facilities laborers then labored mightily for what may have been months; no one really knows. But finally, it was completed. It was painted, and carpeted, and even had plywood veneer paneling on the walls. It also had fluorescent lights in each room. And telephones in each room (but alas, no telephone line filters). And the program occupied the area, setting up their computers and test equipment and their other stuff. After a while, the more troublesome technicians began to wonder why their pagers had no problem functioning within the rooms, and that workers could enjoy FM broadcast radio at their workstations. Wasn't this supposed to be an RF shielded facility? I arrived on site, with spectrum analyzer and trusty loop antenna (three turns of the extended coax center conductor formed into a loop). I'd find those leaks and plug 'em fast. The first thing I noticed was that the room doors were ordinary steel office doors, with painted frames. The fingerstock had been screwed over the painted surfaces. Many of the fingers were broken, bent or missing. And the steel door frame was mounted to the drywall. The RF shield consisted of chicken wire, a wide-mesh, twisted steel wire construction. The name should tell you what it was good for. The average chicken cannot be forced through a chicken wire barrier (at least without significant distortion). AM broadcast radio uses a wavelength long enough that the barrier yields a certain amount of shielding. But FM broadcast slips through like a mosquito. So I started to probe one of the rooms. I just tuned the SA to one of the many convenient signals around 100 MHz, and started to sweep the room. Not only did the mesh screen leak like crazy, but it also turned out that most of those many thousands of drywall screws went right through the wall without touching the mesh. So EACH of these little conductive rods acted as a path for RF in and out of the screen barrier. There were no leaky points; it was like playing laser tag in an infinite hall of mirrors. And, just to show that none of the basics of proper shielding technique had been followed, I found that the powerline filter was located about 75 feet away from the shielded rooms. The filtered power was run to the room in PVC conduit, and the filter was grounded by a six foot long #00 pigtail. After wandering the facility for about two hours, I was approached by the Program Manager, who inquired about my corrective actions. I told him something to the effect that I hadn't been able to find any shielded rooms, but that if we stripped this area clear to the concrete, we could build some right here. I went on to detail that I had seen just about every shielding mistake you could make, all concentrated in one place. This site could qualify only as a museum of inverse shielding. Bad report, bad career action. I went back to testing noisy gadgets that smelled vaguely of ozone. The customer wouldn't let them use the rooms for classified work. A year later, the PM became a VP. -- Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 Date: 03/11/1999 Time: 08:59:26 -- - This message is coming from the emc-pstc discussion list. To cancel your subscription, send
worst emc problem contest
Hello members! Well, as long as we are all trading emc horror stories I might as well pitch in. I have a pretty good one. Just before the launch of Apollo 11 [the first manned moon landing] NASA discovered a big emc problem: something was causing the fuel cells of the command module to short out at random. The command module is the capsule that the astronauts rode in during launch, to the moon, back. This was bad news because you couldn't launch like that, and apollo 11 was already out on the pad, the press was arriving, and the whole world was watching. I was the youngest guy in a 5-man emc section that NASA had at the Kennedy Space Center. A bunch of big-wigs came down from Washington, DC. They told us ( i.e. my boss) to fix it. Money is no object. they said. I, who imagined myself to be a suave, sophisticated New Yorker, was stunned. My jaw just dropped open. I had absolutely no idea how to do do this. To complicate things, we were not allowed to disconnect any cables: configuration control. So my boss, who was a really smart guy, had us build a bunch of huge current probes. Some of them were about 5 ft in diameter. we built two identical pairs of each probe. We set them up around big bundles of cables, and set up a some receivers, timing receivers (clocks), and strip chart recorders. With the help of a large group of contractors (ITT Federal Electric Corp.) we monitored those probes 24 hours a day. Whenever the problem occurred, we ran to the strip charts to see if anything funny had happened in the bundle at that same time. We found time-coincident glitches. Using smaller and smaller current probes, we gradually narrowed the problem down to one cable. The problem turned out to be the following: There were a lot of mechanical relays on the umbilical tower. All of them were supposed to have arc suppression diodes on them. On one relay, someone had installed the diode using leads that were SIX FEET LONG. Needless to say, by the time the impulse hit that diode, it had already been radiated and conducted all over the place. The computer interpreted that glitch as a command to short out the fuel cells. The diode was installed correctly, the problem disappeared, and apollo 11 was launched on time. the public never found out about it. I would love to take credit for this, but it was all my boss's doing. His name was Carl L. Lennon, and I hope he's around somewhere to read this. It was 100% due to him that apollo 11 went off on time. I was just a young dude who would do whatever I was told, instantly, without stopping to ask questions or even to think. Sort of a high tech spear-carrier. Other than a tremendous amount of overtime, I dont think we spent more than $10,000 to solve this problem. I still have a couple of those makeshift current probes. Regards, Louis T. Gnecco M.S.E.E.,President TEMPEST INC. 112 ELDEN ST. HERNDON, VA 20170 (703) TEMPEST (836-7378) l...@tempest-inc.com - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
electromagneticcompatibil...@egroups.com
Members: We have closed our egroup electromagneticcompatibil...@egroups.com and we apologize for the strange ads that were automatically appended by the service. They were not approved by TEMPEST INC. Regards, Louis T. Gnecco, M.S.E.E., President TEMPEST INC. - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
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