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Topic: Extremely Low Frequencies

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	Kids.Net.Au - Encyclopedia > Extremely Low Frequencies
		ELF is used by the US Navy to communicate with submerged submarines.
		The low transmission rate of most ELF communications limits their use as communications channels; generally an ELF signal serves to request that a submarine surface and initiate some other form of contact.
		One of the difficulties posed when broadcasting in the ELF frequency range is antenna size.
	www.kids.net.au /encyclopedia-wiki/ex/Extremely_Low_Frequencies (192 words)

	Biohazards of Extremely Low Frequencies (ELF)
		These are the frequency ranges which can cause disruptions in the human brain.
		The purpose of the system is to create a situation where the ELF signals cannot "lock" onto biological systems -- like human beings.
		The effectiveness of the system would be based upon its actual construction and the ELF power levels in the area.
	www.bibliotecapleyades.net /haarp/esp_HAARP_14.htm (822 words)

	Pearl Drums - Products
		Boosted high frequencies, slightly reduced mids, and a good low end punch for applications requiring extra presence and cut.
		Our African Mahogany is extremely rich in low end frequencies, with beautifully smooth mids and a slight roll-off in the higher frequencies.
		Extremely rich low end frequencies, with beautifully smooth mids and a slight roll-off in the higher frequencies for applications requiring ultimate "bottom" and punch.
	www.pearleurope.com /content/products/default.asp?classmainid=1&classsubid=1 (999 words)

	Re: My audible spectrum is from 56Hz to 20kHz, why isn't it from 20Hz to 20kHz?
		To do your experiment accurately, it would be necessary to use a minimum of three loudspeakers, one for the low frequencies, one for the mid frequencies and one for the high frequencies.
		In the middle frequency region, the function is fairly flat (the bottom part of the "U"), that is, the ear is approximately equally sensitive across the middle frequency region.
		As the frequencies are swept to the higher frequency region the ear becomes less sensitive at a rapid rate (the right arm of the "U").
	www.madsci.org /posts/archives/1998-03/890706301.Ph.r.html (607 words)

	EMF Devices, Neutralizers, Home Protectors, Personal Resonator Technologies and Organite Shields - combat and reduce ...
		All of the known human health hazards from exposure to the ionizing portion of the electromagnetic spectrum are the result of the breaking of chemical bonds in DNA.
		At lower frequencies, such as those characteristic of visible light and radio-frequencies, the energy of a photon is very much below those needed to disrupt chemical bonds.
		At power frequencies, the photon energy is a factor of 10^10 smaller than that needed to break even the weakest chemical bond.
	www.envirohealthtech.com /emfdevice.htm (2645 words)

	Page Title
		frequency until it reaches the DC resistance of the wire.
		Beyond the low frequencies, the obtainable feedback could be as low as 1 dB or even less.
		Remember that feedback compares the output with the input and adjusts the output to match the input, which means that the feedback will flatten the errant frequency response of an amplifier as well as lower its distortion.
	www.tubecad.com /march99/page6.html (547 words)

	It's Your Health - Electric and Magnetic Fields at Extremely Low Frequencies
		Every time you use electricity and electrical appliances, you are exposed to electric and magnetic fields (EMFs) at extremely low frequencies (ELF).
		The term "extremely low" is used to describe any frequency below 300 hertz.
		After a recent evaluation of the scientific data, the International Agency for Research on Cancer classified ELF magnetic fields as "possibly carcinogenic" to humans based on studies of childhood cancer.
	www.hc-sc.gc.ca /iyh-vsv/environ/magnet_e.html (1046 words)

	Nola by Accent Speaker Technology, Ltd.
		Low frequency transients lack sudden and immediate impact because the excess mass cannot be accelerated rapidly.
		Long duration, low frequency tones bury the other frequencies the subwoofer must reproduce, because the driver's high mass, due to momentum, is very slow to stop.
		We alleviated the problem of providing a driver of both low mass and high rigidity by developing a woofer cone that is both extremely rigid yet lighter in weight than Kevlar, aluminum, magnesium and titanium cones.
	www.nolaspeakers.com /products/thunderbolt_b.php (2387 words)

	Extremely Low Frequency Radiation/Power Lines
		The frequency is simply the number of oscillations in the wave per unit time, measured in units of hertz (1 Hz = 1 cycle per second), and the wavelength is the distance travelled by the wave in one oscillation (or cycle).
		At frequencies this low, the wavelengths in air are very long (6000 km at 50 Hz and 5000 km at 60 Hz) and, in practical situations, the electric and magnetic fields act independently of one another and are measured separately.
		Human exposure to ELF fields is primarily associated with the generation, transmission, and use of electrical energy, for example, power lines.
	www.hps.org /hpspublications/articles/elfinfosheet.html (1670 words)

	Extremely Low Frequency Radiation/Power Lines
		The frequency is simply the number of oscillations in the wave per unit time, measured in units of hertz (1 Hz = 1 cycle per second), and the wavelength is the distance travelled by the wave in one oscillation (or cycle).
		At frequencies this low, the wavelengths in air are very long (6000 km at 50 Hz and 5000 km at 60 Hz) and, in practical situations, the electric and magnetic fields act independently of one another and are measured separately.
		Human exposure to ELF fields is primarily associated with the generation, transmission, and use of electrical energy, for example, power lines.
	hps.org /hpspublications/articles/elfinfosheet.html (1670 words)

	Extremely low frequency (ELF) fields (EHC 35, 1984)
		To characterize ELF fields, the strength, frequency, and orientation of the electric and magnetic fields have to be determined.
		The exposure of intact organisms to ELF electric fields is conventionally specified in terms of the unperturbed field strength, in V/m or kV/m, which is measured or calculated before the subject enters the field.
		In his consideration of ELF electric field interactions with neural cells, Schwan (1977) stated that, under a wide range of assumptions for cellular shape and cellular electrical properties, it was impossible that the largest electric fields in air could significantly affect neural membrane potentials by the passage of transmembrane currents.
	www.inchem.org /documents/ehc/ehc/ehc35.htm (16444 words)

	How Elephants Communicate
		African savanna elephants produce a broad range of sounds from very low frequency rumbles to higher frequency trumpets, snorts, screams, barks, roars, cries and other idiosyncratic calls(3.) The most frequently used category of calls is the very low frequency rumble.
		The measured limit of high frequency hearing of air born sound in mammals varies from 12 kHz (elephants) to 114 kHz (little brown bat), and the low frequency hearing limit varies from less than 0.016 kHz (elephants) to 10.3 kHz (little brown bat), a range of more than nine octaves(26).
		In the lower frequencies there tends to be a higher level of background noise, and so animals that specialize in low frequency hearing must have a way of distinguishing signal from noise.
	www.elephantvoices.org /how_comm/acoustic.html (2643 words)

	Aerosol Operation Crimes & Cover Up
		The resonant frequency, or plasma frequency, of the ionosphere(as an example) is of critical importance as to whether or not radio transmissions can be reflected for great distances or not.
		Having a sense that the plasma frequency results in an act of "resonance", it is now helpful to understand what it is that changes the magnitude, or value of the plasma frequency (the plasma frequency can be stated in terms of cycles/sec or radians/sec; they are equivalent).
		The plasma frequency is determined by primarily one thing, and that is the number of electrons in the gas that is being considered.
	www.carnicom.com /elf32.htm (1116 words)

	Consumer Health Articles: ELECTROMAGNETIC POLLUTION
		Their study, published in 1984, showed that exposure to harmful electromagnetic frequencies resulted in altering the behaviour of cells, tissues, organs and organisms; altered hormone levels, altered cell chemistry, altered immune processes, affected calcium ion bonding in cells, modified human brain waves, caused defects in chick embryos, and caused sterility in male animals.
		The World Health Organization has published a report which classified extremely low frequency fields as an environmental health problem in line with mercury and cadmium poisoning, which makes it a toxic problem, but there are presently no regulations on low level radiation produced by power lines and electrical currents.
		A noticeable source of extremely low frequency radiation is the high voltage electrical transmission lines, which in some instances produce such high losses that they bend the earth's ionosphere.
	www.consumerhealth.org /articles/display.cfm?ID=19990303163909 (3553 words)

	WHO \| Electromagnetic fields and public health: extremely low frequency (ELF)
		Human exposure to ELF fields is primarily associated with the generation, transmission and use of electrical energy.
		While it cannot be excluded that ELF field exposure causes cancer from available evidence, further focused, high quality research is now needed to resolve this issue.
		Despite the fact that ELF field levels around transmission and distribution lines are not considered a health risk, siting decisions are often required to take into account aesthetics and public sensibilities.
	www.who.int /mediacentre/factsheets/fs205/en (2758 words)

	Frequencies that can Kill
		There are frequencies we see (such as light waves), hear (sound waves), or feel, and others that are beyond our ability to sense, such as gamma rays, infrared, or radio and television frequencies.
		Or there may be frequencies that we have to deal with on a more regular basis, like the noise we hear when working in a factory, or the sounds of downtown traffic.
		These ELF, which can penetrate anything, have made it possible for the military to have a world-wide communication system with its submarines, which can be situated in any part of the world.
	www.stephen-knapp.com /frequencies_that_can_kill.htm (2433 words)

	Feature Article
		As the frequency extension benefits of a dedicated subwoofer became more and more undeniable, many shifted to the policy of running every loudspeaker “full-range” with a “pure” signal, and then setting the subwoofer to simply “fill in” where the other speakers left off.
		In contrast, any low frequency information produced by separate loudspeakers will not only have different responses in the room due to different physical locations, but there will be cancellations between channels due to distance between them.
		Take the ubiquitous 4th order low pass as an example: At the crossover frequency its phase has come around to 180deg, absolutely inverted (compared to material it is being summed with).
	www.hometheaterhifi.com /volume_9_3/feature-article-multiple-crossovers-9-2002.html (2360 words)

	Rule Broadcast Systems - Tech Tips
		ELF or Extremely Low Frequencies from 0 to 3Khz, VLF or Very Low frequencies range from 3Khz to 30Khz and LF or Low frequencies are transmit at 30Khz to 300Khz.
		Interference occurs when a receiver attempting to pick up the frequency of a specific transmitter, begins to pick up another transmitter sending out RF similar or near the frequency it is scanning for.
		If you hear voices from one system on another system, the frequencies may be on top of each other and the frequency for one of the systems will need to be changed.
	www.rule.com /techtip.cfm?techtipID=55 (1174 words)

	CHRIS STOERMER
		A broad range of radio frequencies (VLF; very low frequency, LF; low frequency, HF; high frequency, and UHF; ultra high frequency) are presently used by the Navy for command and control of the naval fleet, but only the VLF signal can penetrate seawater.
		The acronym ELF, which stands for Extremely Low Frequencies, is one of a number of band designators defined by the Institute of Electrical and Electronics Engineers (IEEE) to name bands or ranges of the electromagnetic frequency spectrum.
		The use of ELF transmissions is based on the principle that energy penetration into a conducting medium such as seawater is inversely proportional to wavelength.
	courseweb.tac.unt.edu /gknezek/99fall/cecs5400/papers/chris.htm (876 words)

	Health Risks of Magnetic Fields at Various Frequencies
		At extremely low frequencies (ELF -- approximately 0-300 Hertz) and very low frequencies (VLF - approximately 300-100,000 Hertz), tissue heating is not a problem, but if induced currents are too strong, there is a risk that they may stimulate electrically excitable cells such as neurons.
		At higher frequencies, the threshold for stimulation of excitable cells increases; between 3kHz and 100kHz, the lowest reported thresholds for cell stimulation are greater than 35f uA/cm², where f is expressed in kilohertz (IEEE, 1992).
		At amplitudes which are too low to stimulate excitable cells, ELF electric and magnetic fields (specifically, 60Hz fields) have been conclusively linked to a small number of health effects, and other health effects have been suggested but not proven.
	www.ifp.uiuc.edu /~hasegawa/emma/node2.html (446 words)

	NIOSH: EMF (Electric and Magnetic Fields): Topic Page \| CDC NIOSH
		This publication is a collection of NIOSH studies and statements on all kinds of health effects from working with VDTs, including studies which found no link between their EMF emissions and reproductive effects.
		This fact sheet answers frequently-asked questions about extremely low frequency (ELF) EMFs in the workplace.
		EMF RAPID was a federal program administered by NIEHS and the Department of Energy, which conducted health effects research and wrote public information documents from 1994-1999.
	www.cdc.gov /niosh/topics/emf (1444 words)

	Extremely Low Frequencies - SourceWatch
		Extremely Low Frequencies (ELF) are the "longest wavelength in the electromagnetic spectrum (>10cm)" which can be "longer than a football field to as short as a football." [1]
		The weak absorption by seawater of ELF waves and prominent resonances in water makes the range suitable for this reflection from the Ionosphere.
		"Although radio waves are practically harmful, ELF waves and oscillating magnetic fields that occur near electric power transmission lines can have adverse effects on human health and the electrochemical balance of the brain.
	www.sourcewatch.org /index.php?title=Extremely_Low_Frequencies (157 words)

	North Country Radio Home Page
		Converts ATV frequencies to VHF CH3 or CH4 (60-72 MHz) for reception using a standard TV receiver.
		channel frequency is set with DIPswitches in 100 kHz increments between 76 and 108 MHz, covering North American, European, and Asian FM frequencies.
		Often gives AM and Low Frequency reception superior to a 100 ft (30 meter) long wire antenna.
	www.northcountryradio.com (2923 words)

	Biohazards of Extremely Low Frequencies (ELF)
		In November, 1995, I asked Dr. Patrick Flanagan if there was a way to guard against low level radiations in the ELF range.
		It is also important to note is that this system will also guard against other ELF sources which may be present in the home which are created by appliances, power lines, etc.
		If you have an interest in obtaining either of these devices we are maintaining an "interest file" for the release of the first production run on this device.
	www.earthpulse.com /haarp/biohazards.html (1089 words)

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