I agree with Mr. Woodgate. Leading off with the Forrestal, without adequately explaining the failure mechanism, gives an unrealistic and misleading introduction to the subject. There was a degraded shield termination that allowed rf to couple to EED leads. For an entity whose emission challenge is CISPR 22 to cite a radar transmission as an "emission" is quite misleading. A better example might be early ABS braking systems to rf transmissions.
on 3/27/03 4:25 AM, King, Richard at richard.k...@uk.thalesgroup.com wrote: > > Dear All, > > Many thanks for your collective help with this question. I attach my final > text below in case others on the list have a use for it. > > ------------------------------------------------------- > Electromagnetic Compatibility (EMC) > > In 1967 off the coast of Vietnam, a jet landing on the aircraft carrier > U.S.S. Forrestal was briefly illuminated by carrier-based radar. This is > quite a normal event, however the energy from the radar caused a stray > electrical signal to be sent to the jet weapon systems. The result was an > uncommanded release of munitions that struck a fully armed and fuelled > fighter on deck. The subsequent explosions killed 134 sailors and caused > severe damage to the carrier and aircraft. > > This article briefly describes the problems caused by Electromagnetic > Interference, what must be done to control it, and the relevance it has to > our work. > > Electromagnetic Interference (EMI) is caused by equipment that emits radio > frequency energy, either deliberately or as a by-product. If this energy > gets into nearby equipment it can degrade or even prevent its normal > operation. This is an important factor in hardware design. Products cannot > be allowed to accidentally cause an aircraft's landing gear to retract, or > crash a nearby life-support machine for example. Just as importantly, > equipment must continue to work reliably when stray energy is present, > shrugging off interference from nearby "noisy" devices (such as the U.S.S. > Forrestal's radar system). > > Electromagnetic Compatibility (EMC) is the science of non-interference. If > two pieces of equipment can operate in the same environment without the loss > of function or performance in either, they are said to be (mutually) > Electromagnetically Compatible. > > To ensure this compatibility for our systems, equipment must be designed to > control its susceptibility to, and its emission of, electromagnetic > interference. This can only be achieved through an engineering planned > process applied over the whole product lifecycle. Careful consideration of > design, procurement, production, site selection, installation, operation, > and maintenance is required. > > .... > > ------------------------------------------------------- > > Best regards, > > > Richard King > Systems Engineer > Thales Communications UK, > > >> -----Original Message----- >> From: King, Richard [SMTP:richard.k...@uk.thalesgroup.com] >> Sent: Monday, March 24, 2003 11:07 AM >> To: 'emc-p...@majordomo.ieee.org' >> Subject: Help wanted with succinct subject description for >> non-specialists >> >> >> Dear all, >> >> I am working on an article about EMC for an internal newsletter. The aim >> is >> to increase awareness of the EMC related projects on which my colleagues >> and >> I are currently engaged. The target audience is largely composed of >> engineers specialising in other subject areas (software, systems and >> hardware), managers and support staff. >> >> To put the piece in context I would like to succinctly describe what EMC >> is >> in an opening couple of paragraphs. However I am struggling to do so in >> language that is easy to read and not full of techno-jargon. >> >> My questions to the list are: What are your experiences of producing >> similar >> material? How well was it received and what is your advice for people >> producing similar text? Are there any examples of good summaries >> available, >> on the web or elsewhere, that people in my position can draw upon for >> inspiration? >> >> My current draft is copied after my signature. Comments or alterations, >> either by direct e-mail or to the list, will be gratefully received. >> >> Thanks in advance, >> >> >> Richard King >> Systems Engineer >> Thales Communications UK. >> >> ==== Begin Draft Subject Description ===== >> >> EMC is two things: >> >> - The resistance of a piece of equipment to external Electromagnetic >> Interference (EMI) >> - The control of a piece of equipment's production of EMI. >> >> If two pieces of equipment can operate in the same Electromagnetic >> Environment (EME) without degradation in the performance or function of >> either, they are said to be mutually Electromagnetically Compatible. >> >> To ensure Compatibility it is necessary to carefully design equipment such >> that both its susceptibility to, and its emission of EMI is controlled. >> Standards exist that define limits for both these aspects. Examples you >> may >> have heard of are the European EMC Directive, which is mandatory for all >> electrical hardware sold in the European Union; and the Defence Standard >> DEF-STAN 59-41, which many of our contracts refer to. >> >> In addition to the distinction between emissions and susceptibility, EMI >> can >> be further classified as either conducted or radiated. The former is >> energy >> transferred via wires or other conductors; and the latter refers to >> electromagnetic waves propagating through free space. >> >> EMC is a necessary consideration for projects that deliver hardware. >> Furthermore, many of the requirements for EMC are common between projects. >> This commonality can be exploited to increase efficiency for individual >> projects and across sites. >> >> ==== End Draft Subject Description ===== >> > Thales Defence (Wells) DISCLAIMER: The information in this message is > confidential and may be legally privileged. It is intended solely for the > addressee. Access to this message by anyone else is unauthorised. If you > are not the intended recipient, any disclosure, copying, or distribution of > the message, or any action or omission taken by you in reliance on it, is > prohibited and may be unlawful. Please immediately contact the sender if > you have received this message in error. Thank you. > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > 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: > Ron Pickard: emc-p...@hypercom.com > Dave Heald: davehe...@attbi.com > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > Archive is being moved, we will announce when it is back on-line. > All emc-pstc postings are archived and searchable on the web at: > http://www.ieeecommunities.org/emc-pstc > -- Ken Javor EMC Compliance Huntsville, Alabama 256/650-5261 This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ 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: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
