Argon is a chemical element with symbol Ar and atomic number 18. It is a noble gas. Argon is the third-most abundant gas in the Earth's atmosphere, at 0.934%. It is more than twice as abundant as water vapor, 23 times as abundant as carbon dioxide, more than 500 times as abundant as neon. Argon is the most abundant noble gas in Earth's crust, comprising 0.00015% of the crust. Nearly all of the argon in the Earth's atmosphere is radiogenic argon-40, derived from the decay of potassium-40 in the Earth's crust. In the universe, argon-36 is by far the most common argon isotope, as it is the most produced by stellar nucleosynthesis in supernovas; the name "argon" is derived from the Greek word ἀργόν, neuter singular form of ἀργός meaning "lazy" or "inactive", as a reference to the fact that the element undergoes no chemical reactions. The complete octet in the outer atomic shell makes argon stable and resistant to bonding with other elements, its triple point temperature of 83.8058 K is a defining fixed point in the International Temperature Scale of 1990.
Argon is produced industrially by the fractional distillation of liquid air. Argon is used as an inert shielding gas in welding and other high-temperature industrial processes where ordinarily unreactive substances become reactive. Argon is used in incandescent, fluorescent lighting, other gas-discharge tubes. Argon makes a distinctive blue-green gas laser. Argon is used in fluorescent glow starters. Argon has the same solubility in water as oxygen and is 2.5 times more soluble in water than nitrogen. Argon is colorless, odorless and nontoxic as a solid, liquid or gas. Argon is chemically inert under most conditions and forms no confirmed stable compounds at room temperature. Although argon is a noble gas, it can form some compounds under various extreme conditions. Argon fluorohydride, a compound of argon with fluorine and hydrogen, stable below 17 K, has been demonstrated. Although the neutral ground-state chemical compounds of argon are presently limited to HArF, argon can form clathrates with water when atoms of argon are trapped in a lattice of water molecules.
Ions, such as ArH+, excited-state complexes, such as ArF, have been demonstrated. Theoretical calculation predicts several more argon compounds that should be stable but have not yet been synthesized. Argon, is named in reference to its chemical inactivity; this chemical property of this first noble gas to be discovered impressed the namers. An unreactive gas was suspected to be a component of air by Henry Cavendish in 1785. Argon was first isolated from air in 1894 by Lord Rayleigh and Sir William Ramsay at University College London by removing oxygen, carbon dioxide and nitrogen from a sample of clean air, they had determined that nitrogen produced from chemical compounds was 0.5% lighter than nitrogen from the atmosphere. The difference was slight, they concluded. Argon was encountered in 1882 through independent research of H. F. Newall and W. N. Hartley; each observed new lines in the emission spectrum of air. Until 1957, the symbol for argon was "A", but now is "Ar". Argon constitutes 0.934% by volume and 1.288% by mass of the Earth's atmosphere, air is the primary industrial source of purified argon products.
Argon is isolated from air by fractionation, most by cryogenic fractional distillation, a process that produces purified nitrogen, neon and xenon. The Earth's crust and seawater contain 0.45 ppm of argon, respectively. The main isotopes of argon found on Earth are 40Ar, 36Ar, 38Ar. Occurring 40K, with a half-life of 1.25×109 years, decays to stable 40Ar by electron capture or positron emission, to stable 40Ca by beta decay. These properties and ratios are used to determine the age of rocks by K–Ar dating. In the Earth's atmosphere, 39Ar is made by cosmic ray activity by neutron capture of 40Ar followed by two-neutron emission. In the subsurface environment, it is produced through neutron capture by 39K, followed by proton emission. 37Ar is created from the neutron capture by 40Ca followed by an alpha particle emission as a result of subsurface nuclear explosions. It has a half-life of 35 days. Between locations in the Solar System, the isotopic composition of argon varies greatly. Where the major source of argon is the decay of 40K in rocks, 40Ar will be the dominant isotope, as it is on Earth.
Argon produced directly by stellar nucleosynthesis, is dominated by the alpha-process nuclide 36Ar. Correspondingly, solar argon contains 84.6% 36Ar, the ratio of the three isotopes 36Ar: 38Ar: 40Ar in the atmospheres of the outer planets is 8400: 1600: 1. This contrasts with the low abundance of primordial 36Ar in Earth's atmosphere, only 31.5 ppmv, comparable with that of neon on Earth and with interplanetary gasses, measured by probes. The atmospheres of Mars and Titan contain argon, predominantly as 40Ar, its content may be as high as 1.93%. The predominance of radiogenic 40Ar is the reason the standard atomic weight of terrestrial argon is greater than that of the next element, potassium, a fact that was
Infrared radiation, sometimes called infrared light, is electromagnetic radiation with longer wavelengths than those of visible light, is therefore invisible to the human eye, although IR at wavelengths up to 1050 nanometers s from specially pulsed lasers can be seen by humans under certain conditions. IR wavelengths extend from the nominal red edge of the visible spectrum at 700 nanometers, to 1 millimeter. Most of the thermal radiation emitted by objects near room temperature is infrared; as with all EMR, IR carries radiant energy and behaves both like a wave and like its quantum particle, the photon. Infrared radiation was discovered in 1800 by astronomer Sir William Herschel, who discovered a type of invisible radiation in the spectrum lower in energy than red light, by means of its effect on a thermometer. More than half of the total energy from the Sun was found to arrive on Earth in the form of infrared; the balance between absorbed and emitted infrared radiation has a critical effect on Earth's climate.
Infrared radiation is emitted or absorbed by molecules when they change their rotational-vibrational movements. It excites vibrational modes in a molecule through a change in the dipole moment, making it a useful frequency range for study of these energy states for molecules of the proper symmetry. Infrared spectroscopy examines transmission of photons in the infrared range. Infrared radiation is used in industrial, military, law enforcement, medical applications. Night-vision devices using active near-infrared illumination allow people or animals to be observed without the observer being detected. Infrared astronomy uses sensor-equipped telescopes to penetrate dusty regions of space such as molecular clouds, detect objects such as planets, to view red-shifted objects from the early days of the universe. Infrared thermal-imaging cameras are used to detect heat loss in insulated systems, to observe changing blood flow in the skin, to detect overheating of electrical apparatus. Extensive uses for military and civilian applications include target acquisition, night vision and tracking.
Humans at normal body temperature radiate chiefly at wavelengths around 10 μm. Non-military uses include thermal efficiency analysis, environmental monitoring, industrial facility inspections, detection of grow-ops, remote temperature sensing, short-range wireless communication and weather forecasting. Infrared radiation extends from the nominal red edge of the visible spectrum at 700 nanometers to 1 millimeter; this range of wavelengths corresponds to a frequency range of 430 THz down to 300 GHz. Below infrared is the microwave portion of the electromagnetic spectrum. Sunlight, at an effective temperature of 5,780 kelvins, is composed of near-thermal-spectrum radiation, more than half infrared. At zenith, sunlight provides an irradiance of just over 1 kilowatt per square meter at sea level. Of this energy, 527 watts is infrared radiation, 445 watts is visible light, 32 watts is ultraviolet radiation. Nearly all the infrared radiation in sunlight is shorter than 4 micrometers. On the surface of Earth, at far lower temperatures than the surface of the Sun, some thermal radiation consists of infrared in the mid-infrared region, much longer than in sunlight.
However, black body or thermal radiation is continuous: it gives off radiation at all wavelengths. Of these natural thermal radiation processes, only lightning and natural fires are hot enough to produce much visible energy, fires produce far more infrared than visible-light energy. In general, objects emit infrared radiation across a spectrum of wavelengths, but sometimes only a limited region of the spectrum is of interest because sensors collect radiation only within a specific bandwidth. Thermal infrared radiation has a maximum emission wavelength, inversely proportional to the absolute temperature of object, in accordance with Wien's displacement law. Therefore, the infrared band is subdivided into smaller sections. A used sub-division scheme is: NIR and SWIR is sometimes called "reflected infrared", whereas MWIR and LWIR is sometimes referred to as "thermal infrared". Due to the nature of the blackbody radiation curves, typical "hot" objects, such as exhaust pipes appear brighter in the MW compared to the same object viewed in the LW.
The International Commission on Illumination recommended the division of infrared radiation into the following three bands: ISO 20473 specifies the following scheme: Astronomers divide the infrared spectrum as follows: These divisions are not precise and can vary depending on the publication. The three regions are used for observation of different temperature ranges, hence different environments in space; the most common photometric system used in astronomy allocates capital letters to different spectral regions according to filters used. These letters are understood in reference to atmospheric windows and appear, for instance, in the titles of many papers. A third scheme divides up the band based on the response of various detectors: Near-infrared: from 0.7 to 1.0 µm. Short-wave infrared: 1.0 to 3 µm. InGaAs covers to about 1.8 µm. Mid-wave infrared: 3 to 5 µm (defined by the atmospheric window and covered by indium antimonide and mercury cadmium telluride and by lead
In geometrical optics, a focus called an image point, is the point where light rays originating from a point on the object converge. Although the focus is conceptually a point, physically the focus has a spatial extent, called the blur circle; this non-ideal focusing may be caused by aberrations of the imaging optics. In the absence of significant aberrations, the smallest possible blur circle is the Airy disc, caused by diffraction from the optical system's aperture. Aberrations tend to get worse as the aperture diameter increases, while the Airy circle is smallest for large apertures. An image, or image point or region, is in focus if light from object points is converged as much as possible in the image, out of focus if light is not well converged; the border between these is sometimes defined using a "circle of confusion" criterion. A principal focus or focal point is a special focus: For a lens, or a spherical or parabolic mirror, it is a point onto which collimated light parallel to the axis is focused.
Since light can pass through a lens in either direction, a lens has two focal points – one on each side. The distance in air from the lens or mirror's principal plane to the focus is called the focal length. Elliptical mirrors have two focal points: light that passes through one of these before striking the mirror is reflected such that it passes through the other; the focus of a hyperbolic mirror is either of two points which have the property that light from one is reflected as if it came from the other. Diverging lenses and convex mirrors do not focus a collimated beam to a point. Instead, the focus is the point from which the light appears to be emanating, after it travels through the lens or reflects from the mirror. A convex parabolic mirror will reflect a beam of collimated light to make it appear as if it were radiating from the focal point, or conversely, reflect rays directed toward the focus as a collimated beam. A convex elliptical mirror will reflect light directed towards one focus as if it were radiating from the other focus, both of which are behind the mirror.
A convex hyperbolic mirror will reflect rays emanating from the focal point in front of the mirror as if they were emanating from the focal point behind the mirror. Conversely, it can focus rays directed at the focal point, behind the mirror towards the focal point, in front of the mirror as in a Cassegrain telescope. Autofocus Cardinal point Defocus aberration Depth of field Depth of focus Far point Focus Fixed focus Bokeh Focus stacking Focal Plane Manual focus
LG Electronics Inc. is a South Korean multinational electronics company headquartered in Yeouido-dong, South Korea, is part of LG Corporation, employing 82,000 people working in 119 local subsidiaries worldwide. With 2014 global sales of USD 55.91 billion, LG comprises four business units: Home Entertainment, Mobile Communications, Home Appliances & Air Solutions, Vehicle Components, with Starion India as its main production vendor for refrigeration and washing machines in the Indian sub-continent. The CEO of LG Electronics is Koo Bon-joon, who assumed the role of vice chairman of LG Electronics on 1 October 2010. Since 2008, LG Electronics remains the world's second-largest television manufacturer. In 1958, LG Electronics was founded as GoldStar, it was established in the aftermath of the Korean War to provide the rebuilding nation with domestically-produced consumer electronics and home appliances. LG Electronics produced South Korea's first radios, TVs, washing machines, air conditioners.
GoldStar was one of the LG groups with a brethren company, Lak-Hui Chemical Industrial Corp., now LG Chem and LG Households. GoldStar merged with Lucky Chemical and LS Cable on 28 February 1995, changing the corporate name to Lucky-Goldstar, finally to LG Electronics. LG Electronics earned US$100 million in revenue from exports for the first time in its history. Rapid growth by globalization saw the company establish its first overseas production, based in the United States, in 1982. In 1994, GoldStar adopted the LG Electronics brand and a new corporate logo. LG Electronics acquired the US-based TV manufacturer Zenith. In 1995, LG Electronics made the world's first CDMA digital mobile handsets and supplied Ameritech and GTE in the US; the company was awarded UL certification in the US. In 1998, LG developed the world's first 60-inch plasma TV, in 1999 established a joint venture with Philips – LG. Philips LCD – which now goes by the name LG Display. In order to create a holding company, the former LG Electronics was split off in 2002, with the "new" LG Electronics being spun off and the "old" LG Electronics changing its name to LG EI.
It was merged with and into LG CI in 2003, so the company that started as Goldstar does not exist. LG Electronics plays a large role in the global consumer electronics industry. By 2005, LG was a Top 100 global brand, in 2006 LG recorded a brand growth of 14%, its display manufacturing affiliate, LG Display, as of 2009 was the world's largest LCD panel manufacturer. In 2010, LG Electronics entered the smartphone industry. Since, LG Electronics continued to develop various electronic products, such as releasing the world's first 84-inch ultra-HD TV for retail sale. On 5 December 2012, the antitrust regulators of the European Union fined LG Electronics and five other major companies for fixing prices of TV cathode-ray tubes in two cartels lasting nearly a decade. On 11 June 2015, LG Electronics found itself in the midst of a human rights controversy when The Guardian published an article by Rosa Moreno, a former employee of an LG television assembly factory. At the end of 2016, LG Electronics merged its German branch and European headquarter together in Eschborn a suburb of Frankfurt am Main.
In March 2017, LG Electronics was sued for its handling of hardware failures with recent smartphones such as the LG G4. In November 2018, LG announced Hwang Jeong-hwan, who took the job as president of LG Mobile Communications in October 2017, will be replaced by Brian Kwon, head of LG's hugely profitable home entertainment business, from 1 December 2018. LG Electronics has four business units: Home Entertainment, Mobile Communications, Home Appliances & Air Solutions, Vehicle Components; the company has 128 operations worldwide. LG Electronics controls 37.9 percent of LG Display. LG Electronics' products include televisions, home theater systems, washing machines, computer monitors, wearable devices, smart appliances, smartphones; the LG SL9000 was one of several new Borderless HDTV's advertised for release at IFA Berlin in 2009. LG Electronics launched an OLED TV in 2013 and 65-inch and 77-inch sizes in 2014. LG Electronics introduced its first Internet TV in 2007 branded as "NetCast Entertainment Access" devices.
They renamed the 2011 Internet televisions to "LG Smart TV" when more interactive television features were added, that enable the audience to receive information from the Internet while at the same time watching conventional TV programming. In November 2013, a blogger discovered that some of LG's smart TVs silently collect filenames from attached USB storage devices and program viewing data, transmit the information to LG's servers and LG-affiliated servers. Shortly after this blog entry went live, LG disabled playback on its site of the video, explaining how its viewer analytics work, closed the Brightcove account the video was hosted on. LG's remote uses Hillcrest Labs' Freespace technology to allow users to change channels using gestures and Dragon NaturallySpeaking technology for voice recognition; as of 2014, LG is using webOS with a ribbon interface with some of its smart TVs. LG reported that in the first eight months after release, it had sold over 5 million webOS TVs. In 2016 to India, Indian arm of South Korea's LG Electronics Inc started selling a TV that would reject mosquitoes.
It uses ultrasonic waves that are silent to
The internal electrodeless lamp or induction lamp is a gas discharge lamp in which an electric or magnetic field transfers the power required to generate light from outside the lamp envelope to the gas inside. This is in contrast to a typical gas discharge lamp that uses internal electrodes connected to the power supply by conductors that pass through the lamp envelope. Eliminating the internal electrodes provides two advantages: Extended lamp life Ability to use higher-efficiency light-generating substances that would react with internal metal electrodes in conventional fluorescent lampsTwo systems are common: plasma lamps, in which electrostatic induction energizes a bulb filled with sulfur vapor or metal halides, fluorescent induction lamps, which are like a conventional fluorescent lamp bulb that induces current with an external coil of wire via electrodynamic induction. Nikola Tesla demonstrated wireless transfer of power to electrodeless lamps in his lectures and articles in the 1890s, subsequently patented a system of light and power distribution on those principles.
In 1967 and 1968, John Anderson of General Electric applied for patents for electrodeless lamps. In 1971, Fusion UV Systems installed a 300-watt electrodeless microwave plasma UV lamp on a Coors can production line. Philips introduced their QL induction lighting systems, operating at 2.65 MHz, in 1990 in Europe and in 1992 in the US. Matsushita had induction light systems available in 1992. Intersource Technologies announced one in 1992, called the E-lamp. Operating at 13.6 MHz, it was available on the US market in 1993. In 1990, Michael Ury, Charles Wood and colleagues formulated the concept of the sulphur lamp. With support from the United States Department of Energy, it was further developed in 1994 by Fusion Lighting of Rockville, Maryland, a spinoff of the Fusion UV division of Fusion Systems Corporation, its origins are in microwave discharge light sources used for ultraviolet curing in the semiconductor and printing industries. Since 1994, General Electric has produced its induction lamp Genura with an integrated ballast, operating at 2.65 MHz.
In 1996, Osram started operating at 250 kHz. It is available in the US as the Sylvania Icetron. In 1997, PQL Lighting introduced in the US the Superior Life Brand induction lighting systems. Most induction lighting systems are rated for 100,000 hours of use before requiring absolute component replacements. In 2005, Amko Solara in Taiwan introduced induction lamps that can use IP based controls, their lamps operate at 250 kHz. From 1995, the former distributors of Fusion, Jenton / Jenact, expanded on the fact that energised UV-emitting plasmas act as lossy conductors to create a number of patents regarding electrodeless UV lamps for sterilising and germicidal uses. Around 2000, a system was developed that concentrated radio frequency waves into a solid dielectric waveguide made of ceramic which energized a light-emitting plasma in a bulb positioned inside; this system, for the first time, permitted an bright and compact electrodeless lamp. The invention has been a matter of dispute. Claimed by Frederick Espiau, Chandrashekhar Joshi and Yian Chang, these claims were disputed by Ceravision Limited.
A number of the core patents were assigned to Ceravision. In 2006, Luxim introduced a projector lamp product trade-named LIFI; the company further extended the technology with light source products in instrument, street and architectural lighting applications among others throughout 2007 and 2008. In 2009, Ceravision Limited introduced the first High Efficiency Plasma lamp under the trade name Alvara; this lamp replaces the opaque ceramic waveguide in earlier lamps with an optically clear quartz waveguide that increases efficiency. In previous lamps, the burner, or bulb, was efficient—but the opaque ceramic waveguide obstructed the projection of light. A quartz waveguide passes all the light from the plasma. In 2012, Topanga Technologies introduced a line of advanced plasma lamps, driven by a solid state radio frequency driver, thereby circumventing the limited life of magnetron-based drivers, with system power of 127 and 230 watts and system efficacies of 96 and 87 lumen/watt, with a CRI of about 70.
Plasma lamps are a family of light sources that generate light by exciting a plasma inside a closed transparent burner or bulb using radio frequency power. Such lamps use a noble gas or a mixture of these gases and additional materials such as metal halides, mercury or sulfur. A waveguide is used to focus the electrical field into the plasma. In operation the gas is ionized and free electrons, accelerated by the electrical field, collide with gas and metal atoms; some electrons circling around the gas and metal atoms are excited by these collisions, bringing them to a higher energy state. When the electron falls back to its original state, it emits a photon, resulting in visible light or ultraviolet radiation depending on the fill materials; the first plasma lamp was an ultraviolet curing lamp with a bulb filled with argon and mercury vapor, developed by Fusion UV. That lamp led Fusion Systems to develop the sulfur lamp, which concentrates microwaves through a hollow waveguide to bombard a bulb filled with argon and sulfur.
In the past, the magnetron that generates the microwaves limited the reliability of electrodeless lamps. Solid state RF generation gives long life. However, using solid state chips to generate RF is around fifty times more expensive than using a magnetron, so only appropriate for high value lighting niches. Dipo
North America is a continent within the Northern Hemisphere and all within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the west and south by the Pacific Ocean, to the southeast by South America and the Caribbean Sea. North America covers an area of about 24,709,000 square kilometers, about 16.5% of the earth's land area and about 4.8% of its total surface. North America is the third largest continent by area, following Asia and Africa, the fourth by population after Asia and Europe. In 2013, its population was estimated at nearly 579 million people in 23 independent states, or about 7.5% of the world's population, if nearby islands are included. North America was reached by its first human populations during the last glacial period, via crossing the Bering land bridge 40,000 to 17,000 years ago; the so-called Paleo-Indian period is taken to have lasted until about 10,000 years ago. The Classic stage spans the 6th to 13th centuries.
The Pre-Columbian era ended in 1492, the transatlantic migrations—the arrival of European settlers during the Age of Discovery and the Early Modern period. Present-day cultural and ethnic patterns reflect interactions between European colonists, indigenous peoples, African slaves and their descendants. Owing to the European colonization of the Americas, most North Americans speak English, Spanish or French, their culture reflects Western traditions; the Americas are accepted as having been named after the Italian explorer Amerigo Vespucci by the German cartographers Martin Waldseemüller and Matthias Ringmann. Vespucci, who explored South America between 1497 and 1502, was the first European to suggest that the Americas were not the East Indies, but a different landmass unknown by Europeans. In 1507, Waldseemüller produced a world map, in which he placed the word "America" on the continent of South America, in the middle of what is today Brazil, he explained the rationale for the name in the accompanying book Cosmographiae Introductio:... ab Americo inventore... quasi Americi terram sive Americam.
For Waldseemüller, no one should object to the naming of the land after its discoverer. He used the Latinized version of Vespucci's name, but in its feminine form "America", following the examples of "Europa", "Asia" and "Africa". Other mapmakers extended the name America to the northern continent, In 1538, Gerard Mercator used America on his map of the world for all the Western Hemisphere; some argue that because the convention is to use the surname for naming discoveries, the derivation from "Amerigo Vespucci" could be put in question. In 1874, Thomas Belt proposed a derivation from the Amerrique mountains of Central America. Marcou corresponded with Augustus Le Plongeon, who wrote: "The name AMERICA or AMERRIQUE in the Mayan language means, a country of perpetually strong wind, or the Land of the Wind, and... the can mean... a spirit that breathes, life itself." The United Nations formally recognizes "North America" as comprising three areas: Northern America, Central America, The Caribbean.
This has been formally defined by the UN Statistics Division. The term North America maintains various definitions in accordance with context. In Canadian English, North America refers to the land mass as a whole consisting of Mexico, the United States, Canada, although it is ambiguous which other countries are included, is defined by context. In the United States of America, usage of the term may refer only to Canada and the US, sometimes includes Greenland and Mexico, as well as offshore islands. In France, Portugal, Romania and the countries of Latin America, the cognates of North America designate a subcontinent of the Americas comprising Canada, the United States, Mexico, Greenland, Saint Pierre et Miquelon, Bermuda. North America has been referred to by other names. Spanish North America was referred to as Northern America, this was the first official name given to Mexico. Geographically the North American continent has many subregions; these include cultural and geographic regions. Economic regions included those formed by trade blocs, such as the North American Trade Agreement bloc and Central American Trade Agreement.
Linguistically and culturally, the continent could be divided into Latin America. Anglo-America includes most of Northern America and Caribbean islands with English-speaking populations; the southern North American continent is composed of two regions. These are the Caribbean; the north of the continent maintains recognized regions as well. In contrast to the common definition of "North America", which encompasses the whole continent, the term "North America" is sometimes used to refer only to Mexico, the United States, Greenland; the term Northern America refers to the northern-most countries and territories of North America: the United States, Bermuda, St. Pierre and Miquelon and Greenland. Although the term does not refer to a unifie
Wi-Fi is technology for radio wireless local area networking of devices based on the IEEE 802.11 standards. Wi‑Fi is a trademark of the Wi-Fi Alliance, which restricts the use of the term Wi-Fi Certified to products that complete after many years of testing the 802.11 committee interoperability certification testing. Devices that can use Wi-Fi technologies include, among others and laptops, video game consoles and tablets, smart TVs, digital audio players, digital cameras and drones. Wi-Fi compatible devices can connect to the Internet via a wireless access point; such an access point has a range of about 20 meters indoors and a greater range outdoors. Hotspot coverage can be as small as a single room with walls that block radio waves, or as large as many square kilometres achieved by using multiple overlapping access points. Different versions of Wi-Fi exist, with radio bands and speeds. Wi-Fi most uses the 2.4 gigahertz UHF and 5 gigahertz SHF ISM radio bands. Each channel can be time-shared by multiple networks.
These wavelengths work best for line-of-sight. Many common materials absorb or reflect them, which further restricts range, but can tend to help minimise interference between different networks in crowded environments. At close range, some versions of Wi-Fi, running on suitable hardware, can achieve speeds of over 1 Gbit/s. Anyone within range with a wireless network interface controller can attempt to access a network. Wi-Fi Protected Access is a family of technologies created to protect information moving across Wi-Fi networks and includes solutions for personal and enterprise networks. Security features of WPA have included stronger protections and new security practices as the security landscape has changed over time. In 1971, ALOHAnet connected the Hawaiian Islands with a UHF wireless packet network. ALOHAnet and the ALOHA protocol were early forerunners to Ethernet, the IEEE 802.11 protocols, respectively. A 1985 ruling by the U. S. Federal Communications Commission released the ISM band for unlicensed use.
These frequency bands are the same ones used by equipment such as microwave ovens and are subject to interference. In 1991, NCR Corporation with AT&T Corporation invented the precursor to 802.11, intended for use in cashier systems, under the name WaveLAN. The Australian radio-astronomer Dr John O'Sullivan with his colleagues Terence Percival, Graham Daniels, Diet Ostry, John Deane developed a key patent used in Wi-Fi as a by-product of a Commonwealth Scientific and Industrial Research Organisation research project, "a failed experiment to detect exploding mini black holes the size of an atomic particle". Dr O'Sullivan and his colleagues are credited with inventing Wi-Fi. In 1992 and 1996, CSIRO obtained patents for a method used in Wi-Fi to "unsmear" the signal; the first version of the 802.11 protocol was released in 1997, provided up to 2 Mbit/s link speeds. This was updated in 1999 with 802.11b to permit 11 Mbit/s link speeds, this proved to be popular. In 1999, the Wi-Fi Alliance formed as a trade association to hold the Wi-Fi trademark under which most products are sold.
Wi-Fi uses a large number of patents held by many different organizations. In April 2009, 14 technology companies agreed to pay CSIRO $1 billion for infringements on CSIRO patents; this led to Australia labeling Wi-Fi as an Australian invention, though this has been the subject of some controversy. CSIRO won a further $220 million settlement for Wi-Fi patent-infringements in 2012 with global firms in the United States required to pay the CSIRO licensing rights estimated to be worth an additional $1 billion in royalties. In 2016, the wireless local area network Test Bed was chosen as Australia's contribution to the exhibition A History of the World in 100 Objects held in the National Museum of Australia; the name Wi-Fi, commercially used at least as early as August 1999, was coined by the brand-consulting firm Interbrand. The Wi-Fi Alliance had hired Interbrand to create a name, "a little catchier than'IEEE 802.11b Direct Sequence'." Phil Belanger, a founding member of the Wi-Fi Alliance who presided over the selection of the name "Wi-Fi", has stated that Interbrand invented Wi-Fi as a pun on the word hi-fi, a term for high-quality audio technology.
Interbrand created the Wi-Fi logo. The yin-yang Wi-Fi logo indicates the certification of a product for interoperability; the Wi-Fi Alliance used the advertising slogan "The Standard for Wireless Fidelity" for a short time after the brand name was created. While inspired by the term hi-fi, the name was never "Wireless Fidelity"; the Wi-Fi Alliance was called the "Wireless Fidelity Alliance Inc" in some publications. Non-Wi-Fi technologies intended for fixed points, such as Motorola Canopy, are described as fixed wireless. Alternative wireless technologies include mobile phone standards, such as 2G, 3G, 4G, LTE; the name is sometimes written as WiFi, Wifi, or wifi, but these are not approved by the Wi-Fi Alliance. IEEE is a separate, but related organization and their website has stated "WiFi is a short name for Wireless Fidelity". To connect to a Wi-Fi LAN, a computer has to be equipped with a wireless network interface controller; the combination of computer and interface controllers is called a station.
A service set is the set of all the devices associated with a particular Wi-Fi network. The service set can be local, extended or mesh; each service set has an associated identifier, the 32-byte Service Set Identifier, which identifies the partic