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Topic: Electromagnetic interference

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	Electromagnetic interference - Wikipedia, the free encyclopedia
		Radio Frequency Interference (RFI) is electromagnetic radiation which is emitted by electrical circuits carrying rapidly changing signals, as a by-product of their normal operation, and which causes unwanted signals (interference or noise) to be induced in other circuits.
		A well documented hazard of using mobile phones is electrical interference with some types of medical equipment, such as ventilators, defribillators, bedside monitoring equipment, in intensive care units.
		Electrical interference with implanted cardiac and neural pacemakers was also observed, particularly with early analog models of handsets, which irradiated with more power.
	en.wikipedia.org /wiki/Electromagnetic_interference (951 words)

	Martek Power Abbott - Electromagnetic Interference
		Interference is defined as any electromagnetic disturbance, phenomenon, signal or emission which causes or can cause undesired response, malfunctioning or degradation of performance of electrical and electronic equipment.
		Conducted Interference is an undesirable electromagnetic energy appearing on the external conductors (input and output leads of a power supply) which may be conducted into other sensitive equipment and cause malfunction or otherwise affect the operation of the equipment.
		Radiated Interference is the propagation of electromagnetic energy without a direct conducting path, and is generally the result of electromagnetic fields around external wiring or inadequate shielding afforded by the power supply case.
	www.martekpowerabbott.com /engineer/emi.htm (864 words)

	Electromagnetic interference
		Interference is any unwanted radio frequency signal that prevents you from watching television, listening to your radio or stereo, or talking on your telephone.
		Interference may prevent reception altogether, may cause only a temporary loss of a signal, or may affect the quality of the sound or picture produced by your equipment.
		A simple method of determining the location of electrical interference is by using a portable AM radio tuned to a quiet frequency at the lower end of the dial.
	www.callingbargains.com /telephone-interference.htm (708 words)

	Electromagnetic Interference In High Reliability Electrical Interconnect Systems - Glenair, Inc.
		Electromagnetic Interference (EMI), defined by NATO as an electromagnetic disturbance which interrupts, obstructs, or otherwise degrades the effective performance of electronic or electrical equipment.
		Electromagnetic Interference (EMI), defined by NATO as an electromagnetic disturbance which interrupts, obstructs, or otherwise degrades the effective performance of electronic or electrical equipment, had claimed another victim.
		In both cases, the techniques for managing the interference include reflecting the signals outright, reducing entry points in equipment and cable shields, absorbing the interference in permeable material and dissipating it as heat, or conducting the EMI along the skin of the device/cable and taking it to ground.
	www.glenair.com /html/emi.htm (2879 words)

	EMI - ElectroMagnetic Interference
		Interference by electromagnetic signals that can cause reduced data integrity and increased error rates on transmission channels.
		Electromagnetic Interference: Equipment used in high speed data systems, including ATM, that generate and transmit many signals in the radio frequency portion of the electromagnetic spectrum.
		Electromagnetic interference Interference to the operation of communications products or other electrical and electronic devices generated by all electrical and electronic products or natural causes.
	www.auditmypc.com /acronym/EMI.asp (386 words)

	(EMC) Electromagnetic Interference in Medical Devices (MEM archive, Sep 01)
		Electromagnetic interference (EMI) has been responsible for a variety of medical-electronics malfunctions, which has raised concerns for patient safety.
		Interference of the line isolation system in an intensive care unit with the performance of a defibrillator.
		Interference by security systems such as EAS systems and walk-through metal detectors on pace- makers may pose a potential risk, depending on the model of pacemaker, the programmed mode, and the type of the security system.
	www.devicelink.com /mem/archive/01/09/010.html (3495 words)

	Electromagnetic interference with aircraft systems
		Five crashes of Blackhawk helicopters shortly after their introduction into service in the late 1980's were found to be due to electromagnetic interference from very strong radar and radio transmitters with the electronic flight control systems (1).
		While interference is not proven, he believes it gives considerable cause for concern; and that while it may be difficult to demonstrate the relationship using Brunnstein's `forensic' criterion, this could be due to the fact that the equipment needed to do so is not on board the aircraft at the times the incidents occur.
		He also notes that most electromagnetic interference testing is `bench-testing', performed on independent subsystems, and that this may suggest an interesting suspect point of weakness in the aircraft, namely the system interconnections.
	www.rvs.uni-bielefeld.de /publications/Incidents/DOCS/Research/Rvs/Article/EMI.html (6231 words)

	Electromagnetic interference (Site not responding. Last check: 2007-11-06)
		Electromagnetic interference or EMI is any electromagnetic disturbance that interrupts, obstructs, or otherwise degrades or limits the effective performance of electronic or electrical equipment.
		Single Antenna Interference Cancellation (SAIC) is a very interesting and promising technology currently being standardized in 3GPP as part of GERAN Release 6.
		This interference reduction technique takes advantage of the latest developments in signal processing and receiver algorithms in a cost-efficient way.
	www.serebella.com /encyclopedia/article-Electromagnetic_interference.html (619 words)

	Electromagnetic Interference
		This document is intended to describe the principal causes of electromagnetic interference and present a methodology for reducing the potential risks associated with EMI in the health care environment.
		The amount of electromagnetic energy emitted by a device (or to which a device may be (susceptible to) is commonly expressed in terms of its electric field strength, and is typically given in the units of volts per meter (V/m).
		When electromagnetic interference is suspected, the first step in resolving the problem is to determine the mechanism for energy transfer to the affected device(s): radiation, conduction, or induction.
	www.ibet.asttbc.org /emi.htm (5667 words)

	TFCBooks -- Tesla Site Glossary
		Electromagnetics governs current flow in the conductor up to the capacitor, then "current" becomes an electrodynamic event in the dielectric, and finally current again becomes an EM event in the conductor on the other side of the capacitor.
		electromagnetic energy to determine, exploit, reduce or prevent hostile use of the electromagnetic spectrum and action which retains friendly use of the electromagnetic spectrum.
		Electromagnetic waves of sufficiently short wavelength that practical use can be made of waveguide and associated cavity techniques in their transmission and reception.
	www.tfcbooks.com /mainpage/glossary.htm (12260 words)

	EMC - EMI explained, Electromagnetic Compatability, electromagnetic interference (Site not responding. Last check: 2007-11-06)
		Electromagnetic compatibility - EMC electromagnetic interference (EMI) and Radio Frequency Interference (RFI) are usually caused by the rapid switching action of semiconductors, relays, etc. resulting in undesirable currents and voltages
		Electromagnetic interference Electromagnetic interference is caused by undesireable radiated electromagnetic fields or conducted voltages and currents,...
		Radio Frequency Interference (RFI) is a distortion on the AC or DC line sent via a radiated signal and received by the conductive path of the circuit.
	users.telenet.be /educypedia/electronics/emc-emi.htm (557 words)

	Electromagnetic Interference (EMI) on TV Antenna Systems - Stallions Satellite and Antenna
		This kind of interference ususally disappears after it has been raining steadily for several hours and the ground is saturated with water, thus grounding all of the utility poles and greatly reducing the amount of static electricity that is radiated into the air from the transformers and/or lines.
		If the interference is coming from inside of your house, you will know it as soon as you turn off the circuit that the offending source is plugged into.
		If you find that the offending interference on your TV is coming from outside the house, have the power company come out when you are home and show them the problem on your TV(s) and what you found out when you walked around with the AM radio.
	www.tvantenna.com /support/tutorials/emi.html (915 words)

	Interference
		The result of adding two waves of the same frequency depends on the value of the phase of the wave at the point in which the waves are added.
		When the light from the two sources is projected on a screen, an interference pattern is observed.
		To explain the origin of the interference pattern, consider the distance traveled from the two sources.
	members.tripod.com /~vsg/interfer.htm (241 words)

	The New York Review of Books: Swissair 111, TWA 800, and Electromagnetic Interference
		This second line of inquiry—electromagnetic interference from a source external to the plane's own wiring (internal and external sources of ignition are not mutually exclusive:damaged wiring inside a plane can increase its vulnerability to external transmissions)—is the subject of the article that follows.
		The three accidents viewed together, however, greatly increase the need to assess with precision the possible role of electromagnetic interference: the occurrence of three accidents in a single area increases the chance that something in the external environment is acting as a contributing factor.
		(Electromagnetic interference, as stated at the outset, can just as easily happen at irregular as at regular times and places, though the irregularity of the external environment makes it harder to discern that the external environment is playing a part).
	www.nybooks.com /articles/13898 (8950 words)

	EMI Theory
		Electronic devices operating normally in their intended environment, without conducting or radiating excessive amounts of electromagnetic energy, or being susceptible to such energy from internal or external sources, are in the state of electromagnetic compatibility, or EMC.
		Electromagnetic interference, EMI, is radiated or conducted energy that adversely affects circuit performance, and thus disrupts a device’s EMC.
		As in the case of internal sources, conducted EMI may be reduced with filtering devices on incoming and outgoing leads as shown in Figure 1b, and susceptibility to externally radiated EMI may be reduced with use of effective shielding, as illustrated in Figure 1c.
	www.parker.com /chomerics/tech/EMITHEORY.htm (607 words)

	Electromagnic Compatibility (EMC) and Wireless Medical Devices - Medical Devices and EMI: The FDA Perspective
		Over the years, many incidents of suspected electromagnetic interference (EMI) with medical devices have been documented.[4] In addition, recent congressional hearings [5] and media attention [6,7] have heightened concern for the safe and effective use of devices in the presence of EMI.
		EMC means that the device is compatible with (i.e., no interference caused by) its EM environment, and it does not emit levels of EM energy that cause EMI in other devices in the vicinity.
		In general, the strength of the EM field at any given distance from the source of the radiated signal (transmitter) is directly proportional to the radiated power of the transmitter and inversely proportional to the distance.
	www.fda.gov /cdrh/emc/persp.html (3720 words)

	EMI
		A servo-ventilator was tested in a gigahertz transverse electromagnetic (GTEM) cell using standardized methods for interference of function from RF electric field strengths of 3 and 10 volts per meter.
		Interference, which took the form of a buzzing tone, was perceived up to 47 cm away from the transmitting phone.
		The level of induced interference in the ITE hearing aids as well as six behind-the-ear (BTE) hearing aids was quantified using a sound pressure level (SPL) meter with a calibrated microphone.
	www.fda.gov /cdrh/ost/reports/fy95/emi.html (1900 words)

	Hearing Aids and EMI (Electromagnetic Interference)
		In the past, telecoils were so weak that even people who turned up their hearing aids to full volume had difficulty picking up the desired signals from the telephone or assistive listening devices connected to the television, radio, or stereo.
		When the telecoil's sensitivity is increased, so is the possibility of interference from other electromagnetic sources, such as fluorescent lights, electric motors, overhead projectors, computer monitors, printers, and other equipment.
		Electromagnetic interference would be a problem for them as well.
	www.zak.co.il /deaf-info/old/hearing_aids_emi.html (886 words)

	Professor Proposes Electromagnetic Interference Downed TWA Flight 800 (Site not responding. Last check: 2007-11-06)
		EDT http://www.nandotimes.com) -- A Harvard University English professor believes electromagnetic interference -- possibly from military craft -- might be responsible for the downing of TWA Flight 800.
		Electromagnetic signals from other craft could have prompted an electrical charge aboard TWA 800 to jump from high-voltage wires to low-voltage wires and then travel to the fuel gauge and the fuel tank.
		Electromagnetic interference is suspected as the cause of at least six military disasters, Scarry said.
	www.anomalous-images.com /news/news209.html (376 words)

	ARRLWeb: Electromagnetic interference and the cable operator
		If, for example, interference is due to leakage in the wiring located in the subscriber's home or in the subscriber's TV receiver, asking the transmitter operator to correct the problem by making changes to the radio station will not result in a cure.
		There are three components to any interference problem: (1) a source of radio-frequency energy or electrical noise, (2) a piece of susceptible equipment and (3) a path over which the unwanted energy is propagated.
		If the station is not causing interference to an antenna-connected TV set located on the premises (often at home), this usually indicates that the transmitter is not transmitting any interfering out-of-band signals.
	www.arrl.org /tis/info/HTML/catvi (6425 words)

	Electromagnetic Interference (EMI) - Overview - FMS
		Electromagnetic Interference or EMI, has been defined as the "degradation of the performance of a piece of equipment, transmission channel, or system caused by an electromagnetic disturbance." (ANSI C63.14, 1992; IEC 60050(161), 1990).
		If the susceptible device does not have sufficient immunity to reject the energy it is being exposed to, electromagnetic interference may occur.
		FMS has been eliminating electromagnetic interference issues in commercial and industrial buildings, medical facilities, and research laboratories for over ten years.
	www.fms-corp.com /interferenceconcerns_overview.php4 (427 words)

	Report on Electromagnetic Interference in Hospitals
		In England, then NHS (National Health Service) issued report DB9702, "Electromagnetic Compatibility of Medical Devices with Mobile Communications." In that 1997 report, only 4% of handheld transmitters (all types) cause any interference at a distance of one meter (3 feet).
		At a distance of 1m; 41% of medical devices suffered interference from emergency services handsets, 35% suffered interference from security/porters handsets but only 4% from cellphones.
		No significant levels of interference were detected from cordless handsets/local area networks or cellular base stations." The report has not been updated.
	www.pdacortex.com /EMI.htm (874 words)

	Food and Drug Administration (FDA) Concerned with Electromagnetic Interference (EMI) Problems
		The FDA, as the primary agency overseeing the safety of electronic medical devices, has recently increased its interest in reports of electromagnetic interference with the function of electronic medical devices and motorized aids like wheelchairs and scooters.
		FDA is receiving inquiries about reports that electromagnetic interference (EMI) can cause some power- driven wheelchairs and scooters to move unexpectedly.
		There have been reports, for example, that patient breathing monitors failed to alarm when needed because of radio wave interference that cellular phones, when used too close to an electronic medical device, have interfered with the device's operation; and that radio wave interference causes some power-driven wheelchairs to move unexpectedly.
	www.infoventures.com /emf/federal/fda/emi-fda.html (1207 words)

	Electromagnetic Interference Laboratory - Description (Site not responding. Last check: 2007-11-06)
		Walls, ceiling, and floors are constructed of 26-gauge galvanized steel sheets laminated to both sides of a structural core.
		They prevent transmission of electromagnetic waves into, or out of, the enclosure, which provides low electric and magnetic field ambient conditions.
		Electrical power is provided through filtered AC lines to eliminate transfer of interfering signals such as radio, TV, and RADAR.
	facilities.grc.nasa.gov /emi/emi_desc.html (89 words)

	Sources of Electromagnetic Interference (EMI)
		The device may sense electromagnetic interference from small hammers, thus generating inappropriate therapy.
		Interference has been noted when in close proximity to the detection poles.
		The special tags attached to store merchandise as part of theft detection systems are deactivated at the checkout counter by either running the merchandise over a scanner or using a hand-held deactivator.
	www.guidant.com /patient/living (2179 words)

	Electromagnetic Interference - Siemon
		When cable is in close proximity to strong electromagnetic fields, unwanted current and voltage may be induced on it.
		In data communication, excessive electromagnetic interference (EMI) hinders the ability of remote receivers to successfully detect data packets.
		While electromagnetic interference can affect the performance quality of structured cabling systems, there are two effective methods to help avoid this: shielding and physical separation.
	www.siemon.com /us/white_papers/02-03-22-emi.asp (1241 words)

	Citations: Statistical-physical models of electromagnetic interference - Middleton (ResearchIndex) (Site not responding. Last check: 2007-11-06)
		It is usually understood in such a way that the in phase and the quadrature components of the transmitted signal pass through the Gaussian channel whose variance is a random variable.
		The problem with Middleton s models is that they are mathematically difficult, and even though they are based on familiar physical situations, the connection to the physical scenario is not apparent [27] This is probably the reason why these models have not been adopted as standard tools in....
		Mathematical expressions were developed for the received and match filtered signal at a single antenna that results from the interference generated by a collection of emitters in the space around the antenna.
	citeseer.ist.psu.edu /context/97081/0 (2096 words)

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