Wiktionary
n. (context electronics English) The band of radio frequency from 3 to 30 hertz
WordNet
n. below 3 kilohertz [syn: ELF]
Wikipedia
Extremely low frequency (ELF) is the ITU designation for electromagnetic radiation ( radio waves) with frequencies from 3 to 30 Hz, and corresponding wavelengths from 100,000 to 10,000 kilometers. In atmospheric science, an alternative definition is usually given, from 3 Hz to 3 kHz. In the related magnetosphere science, the lower frequency electromagnetic oscillations (pulsations occurring below ~3 Hz) are considered to lie in the ULF range, which is thus also defined differently from the ITU radio bands.
ELF radio waves are generated by lightning and natural disturbances in Earth's magnetic field, so they are a subject of research by atmospheric scientists. Because of the difficulty of building antennas that can radiate such long waves, ELF frequencies have been used in only a very few human-made communication systems. ELF waves can penetrate seawater, which makes them useful in communication with submarines. The US, Russia, and India are the only nations known to have constructed ELF communication facilities. The U.S. facilities were used between 1985 and 2004 but are now decommissioned. ELF waves can also penetrate significant distances into earth or rock, and " through-the-earth" underground mine communication systems use frequencies of 300 to 3000 Hz. The frequency of alternating current flowing in electric power grids, 50 or 60 Hz, also falls within the ELF band, making power grids an unintentional source of ELF radiation.
Usage examples of "extremely low frequency".
When that palled I would plot the destruction of Gorshkov, that prick on wheels, and the KGB schemer Andropov, whose hobbyhorse this whole bioenergetics farce is, and put an end to it, and get on with the Extremely Low Frequency Broadcaster, just as the Yankees have done.
Somewhere in Connecticut is the world's largest radio transmitter, using an extremely low frequency, which can contact us at this depth far more easily than any other radio station can contact a surface ship.
For communications, they were equipped with the SSIXS (Submarine Satellite Information Exchange System) UHF SATCOM communication systems, as well as the ability to receive VLF (Very Low Frequency) and ELF (Extremely Low Frequency) messages.
Fiber-optic land-lines carried a similar notice to the Navy's Extremely Low Frequency radio system located in Michigan's Upper Peninsula region.
Several Excise men suffered similar fates and all the time the artillery bombardment continued, the rifle fire increased, the high-frequency whistle blew fit to bust and Mr Mirkin clutching his head in agony took an unwise step forward, fell and lay on an extremely large loudspeaker which was resonating at an extremely low frequency.
When exposed to extremely low frequency (ELF) signals, the insects sealed up their hives in mid-season and stopped producing honey.
If necessary, she could still be reached by the relatively new, albeit slow, ELF, or extremely low frequency, band of communications.
If Tamara's talent could be taught to others, the Soviet Navy could scrub its own Extremely Low Frequency Broadcaster Project.
We get a CPS, and this has now been confirmed on an ordinary savvyometer, which we modified to accommodate an extremely low frequency range.