A1 Telekom Austria Group
A1 Telekom Austria Group is a provider of a range of fixed-line, broadband Internet, multimedia services, IT solutions, wholesale as well as mobile payment solutions. Its headquarters are in Vienna; the company operates subsidiaries in eight European countries: Austria, Bulgaria, Liechtenstein, North Macedonia and Slovenia. Its largest subsidiary is the Austrian telecommunications provider A1 Telekom Austria. Telekom Austria's earliest predecessor, the state-owned K. K Post- und Telegraphenverwaltung, was formed in 1887 when all telephone and mail services in Austria-Hungary were taken over by the state. After World War I, the Austrian portion of the company became Post- und Telegraphenverwaltung. In 1996, with the passage of the Post Restructuring Act, PTV was restructured as a public corporation, Post-und Telekom Austria AG. Only two years the telecommunications sector was deregulated and PTA was split, with the telecom side becoming Telekom Austria; the company was privatised in 2000 and was listed on the Vienna Stock Exchange and the New York Stock Exchange.
In June 2000, the company invested about 15 million euros to rebrand itself as Jet2Web. However, Jet2Web failed to succeed in the market; the use of the name was discontinued in 2002, the company name Telekom Austria was revived as the brand name with a new logo. In June 2006, the company was split into the holding company Telekom Austria Group, with the public switched telephone network becoming Telekom Austria FixNet AG, renamed Telekom Austria TA AG. In doing so, Telekom Austria FixNet AG became a sister company of affiliate Mobilkom Austria AG. Both merged in 2010 to form A1 Telekom Austria. Foreign subsidiaries of Mobilkom Austria were transferred to the holding company, so that A1 Telekom Austria would only deal with the Austrian market. In 2011, misdemeanours by company directors between 2004 and 2006 became public, erupting into a scandal known as the Telekom-Affäre; as of the end of 2016, Telekom Austria Group had 18,203 employees and generated about €4.2 billion in revenues. On November 14, 2017, Telekom Austria Group was rebranded to A1 Telekom Austria Group as part of adopting their one brand strategy.
The legal entity Telekom Austria AG still remains. On 23 April 2014 Carlos Slim, owner of America Movil, took control of Telekom Austria by forming a syndicate agreement between ÖIAG and America Movil, spending as much as $2 billion to buy out minority shareholders and investing up to 1 billion euros into the company. America Movil sees Telekom Austria as a "platform for expansion into Central and Eastern Europe". Labour representatives boycotted the decision on the syndicate agreement at the ÖIAG supervisory board meeting for 12 hours criticising lack of explicit job guarantees. Telekom Austria operates the following subsidiaries in foreign markets: velcom A1 Bulgaria A1 Hrvatska Telecom Liechtenstein FL1 Mobilkom Liechtenstein ONE. VIP Vip mobile A1 Slovenija Official website Vienna Stock Exchange: Telekom Austria AG
GSM is a standard developed by the European Telecommunications Standards Institute to describe the protocols for second-generation digital cellular networks used by mobile devices such as mobile phones and tablets. It was first deployed in Finland in December 1991; as of 2014, it has become the global standard for mobile communications – with over 90% market share, operating in over 193 countries and territories.2G networks developed as a replacement for first generation analog cellular networks, the GSM standard described a digital, circuit-switched network optimized for full duplex voice telephony. This expanded over time to include data communications, first by circuit-switched transport by packet data transport via GPRS and EDGE. Subsequently, the 3GPP developed third-generation UMTS standards, followed by fourth-generation LTE Advanced standards, which do not form part of the ETSI GSM standard. "GSM" is a trademark owned by the GSM Association. It may refer to the most common voice codec used, Full Rate.
In 1983, work began to develop a European standard for digital cellular voice telecommunications when the European Conference of Postal and Telecommunications Administrations set up the Groupe Spécial Mobile committee and provided a permanent technical-support group based in Paris. Five years in 1987, 15 representatives from 13 European countries signed a memorandum of understanding in Copenhagen to develop and deploy a common cellular telephone system across Europe, EU rules were passed to make GSM a mandatory standard; the decision to develop a continental standard resulted in a unified, standard-based network, larger than that in the United States. In February 1987 Europe produced the first agreed GSM Technical Specification. Ministers from the four big EU countries cemented their political support for GSM with the Bonn Declaration on Global Information Networks in May and the GSM MoU was tabled for signature in September; the MoU drew in mobile operators from across Europe to pledge to invest in new GSM networks to an ambitious common date.
In this short 38-week period the whole of Europe had been brought behind GSM in a rare unity and speed guided by four public officials: Armin Silberhorn, Stephen Temple, Philippe Dupuis, Renzo Failli. In 1989 the Groupe Spécial Mobile committee was transferred from CEPT to the European Telecommunications Standards Institute. In parallel France and Germany signed a joint development agreement in 1984 and were joined by Italy and the UK in 1986. In 1986, the European Commission proposed reserving the 900 MHz spectrum band for GSM; the former Finnish prime minister Harri Holkeri made the world's first GSM call on July 1, 1991, calling Kaarina Suonio using a network built by Telenokia and Siemens and operated by Radiolinja. The following year saw the sending of the first short messaging service message, Vodafone UK and Telecom Finland signed the first international roaming agreement. Work began in 1991 to expand the GSM standard to the 1800 MHz frequency band and the first 1800 MHz network became operational in the UK by 1993, called and DCS 1800.
That year, Telecom Australia became the first network operator to deploy a GSM network outside Europe and the first practical hand-held GSM mobile phone became available. In 1995 fax, data and SMS messaging services were launched commercially, the first 1900 MHz GSM network became operational in the United States and GSM subscribers worldwide exceeded 10 million. In the same year, the GSM Association formed. Pre-paid GSM SIM cards were launched in 1996 and worldwide GSM subscribers passed 100 million in 1998. In 2000 the first commercial GPRS services were launched and the first GPRS-compatible handsets became available for sale. In 2001, the first UMTS network was launched, a 3G technology, not part of GSM. Worldwide GSM subscribers exceeded 500 million. In 2002, the first Multimedia Messaging Service was introduced and the first GSM network in the 800 MHz frequency band became operational. EDGE services first became operational in a network in 2003, the number of worldwide GSM subscribers exceeded 1 billion in 2004.
By 2005 GSM networks accounted for more than 75% of the worldwide cellular network market, serving 1.5 billion subscribers. In 2005, the first HSDPA-capable network became operational; the first HSUPA network launched in 2007. Worldwide GSM subscribers exceeded three billion in 2008; the GSM Association estimated in 2010 that technologies defined in the GSM standard served 80% of the mobile market, encompassing more than 5 billion people across more than 212 countries and territories, making GSM the most ubiquitous of the many standards for cellular networks. GSM is a second-generation standard employing time-division multiple-Access spectrum-sharing, issued by the European Telecommunications Standards Institute; the GSM standard does not include the 3G Universal Mobile Telecommunications System code division multiple access technology nor the 4G LTE orthogonal frequency-division multiple access technology standards issued by the 3GPP. GSM, for the first time, set a common standard for Europe for wireless networks.
It was adopted by many countries outside Europe. This allowed subscribers to use other GSM networks; the common standard reduced research and development costs, since ha
FM broadcasting is a method of radio broadcasting using frequency modulation technology. Invented in 1933 by American engineer Edwin Armstrong, wide-band FM is used worldwide to provide high-fidelity sound over broadcast radio. FM broadcasting is capable of better sound quality than AM broadcasting, the chief competing radio broadcasting technology, so it is used for most music broadcasts. Theoretically wideband AM can offer good sound quality, provided the reception conditions are ideal. FM radio stations use the VHF frequencies; the term "FM band" describes the frequency band in a given country, dedicated to FM broadcasting. Throughout the world, the FM broadcast band falls within the VHF part of the radio spectrum. 87.5 to 108.0 MHz is used, or some portion thereof, with few exceptions: In the former Soviet republics, some former Eastern Bloc countries, the older 65.8–74 MHz band is used. Assigned frequencies are at intervals of 30 kHz; this band, sometimes referred to as the OIRT band, is being phased out in many countries.
In those countries the 87.5–108.0 MHz band is referred to as the CCIR band. In Japan, the band 76–95 MHz is used; the frequency of an FM broadcast station is an exact multiple of 100 kHz. In most of South Korea, the Americas, the Philippines and the Caribbean, only odd multiples are used. In some parts of Europe and Africa, only multiples are used. In the UK odd or are used. In Italy, multiples of 50 kHz are used. In most countries the maximum permitted frequency error is specified, the unmodulated carrier should be within 2000 Hz of the assigned frequency. There are other unusual and obsolete FM broadcasting standards in some countries, including 1, 10, 30, 74, 500, 300 kHz. However, to minimise inter-channel interference, stations operating from the same or geographically close transmitter sites tend to keep to at least a 500 kHz frequency separation when closer frequency spacing is technically permitted, with closer tunings reserved for more distantly spaced transmitters, as interfering signals are more attenuated and so have less effect on neighboring frequencies.
Frequency modulation or FM is a form of modulation which conveys information by varying the frequency of a carrier wave. With FM, frequency deviation from the assigned carrier frequency at any instant is directly proportional to the amplitude of the input signal, determining the instantaneous frequency of the transmitted signal; because transmitted FM signals use more bandwidth than AM signals, this form of modulation is used with the higher frequencies used by TV, the FM broadcast band, land mobile radio systems. The maximum frequency deviation of the carrier is specified and regulated by the licensing authorities in each country. For a stereo broadcast, the maximum permitted carrier deviation is invariably ±75 kHz, although a little higher is permitted in the United States when SCA systems are used. For a monophonic broadcast, again the most common permitted. However, some countries specify a lower value for monophonic broadcasts, such as ±50 kHz. Random noise has a triangular spectral distribution in an FM system, with the effect that noise occurs predominantly at the highest audio frequencies within the baseband.
This can be offset, to a limited extent, by boosting the high frequencies before transmission and reducing them by a corresponding amount in the receiver. Reducing the high audio frequencies in the receiver reduces the high-frequency noise; these processes of boosting and reducing certain frequencies are known as pre-emphasis and de-emphasis, respectively. The amount of pre-emphasis and de-emphasis used is defined by the time constant of a simple RC filter circuit. In most of the world a 50 µs time constant is used. In the Americas and South Korea, 75 µs is used; this applies to both stereo transmissions. For stereo, pre-emphasis is applied to the left and right channels before multiplexing; the use of pre-emphasis becomes a problem because of the fact that many forms of contemporary music contain more high-frequency energy than the musical styles which prevailed at the birth of FM broadcasting. Pre-emphasizing these high frequency sounds would cause excessive deviation of the FM carrier. Modulation control devices are used to prevent this.
Systems more modern than FM broadcasting tend to use either programme-dependent variable pre-emphasis. Long before FM stereo transmission was considered, FM multiplexing of other types of audio level information was experimented with. Edwin Armstrong who invented FM was the first to experiment with multiplexing, at his experimental 41 MHz station W2XDG located on the 85th floor of the Empire State Building in New York City; these FM multiplex transmissions started in November 1934 and consisted of the main channel audio program and three subcarriers: a fax program, a synchronizing signal for the fax program and a telegraph “order” channel. These original FM multiplex subcarriers were amplitude modulated. Two musical programs, consisting of both the Red and Blue Network program feeds of the NBC Radio Network, were transmitted using the same system of subcarrier modulation as part of a studio-to-transmitter link system. In April 1935, the AM subcarriers were replaced with much improved results.
The first FM subcarrier transmissions emanating from Major Armstrong's experimental station KE2XCC at Alpine, New Jersey occurred in 1948. These transmissions consisted of two-cha
Integrated Services Digital Network
Integrated Services Digital Network is a set of communication standards for simultaneous digital transmission of voice, video and other network services over the traditional circuits of the public switched telephone network. It was first defined in 1988 in the CCITT red book. Prior to ISDN, the telephone system was viewed as a way to transport voice, with some special services available for data; the key feature of ISDN is that it integrates speech and data on the same lines, adding features that were not available in the classic telephone system. The ISDN standards define several kinds of access interfaces, such as Basic Rate Interface, Primary Rate Interface, Narrowband ISDN, Broadband ISDN. ISDN is a circuit-switched telephone network system, which provides access to packet switched networks, designed to allow digital transmission of voice and data over ordinary telephone copper wires, resulting in better voice quality than an analog phone can provide, it offers circuit-switched connections, packet-switched connections, in increments of 64 kilobit/s.
In some countries, ISDN found major market application for Internet access, in which ISDN provides a maximum of 128 kbit/s bandwidth in both upstream and downstream directions. Channel bonding can achieve a greater data rate. ISDN is employed as data-link and physical layers in the context of the OSI model. In common use, ISDN is limited to usage to Q.931 and related protocols, which are a set of signaling protocols establishing and breaking circuit-switched connections, for advanced calling features for the user. They were introduced in 1986. In a videoconference, ISDN provides simultaneous voice and text transmission between individual desktop videoconferencing systems and group videoconferencing systems. Integrated services refers to ISDN's ability to deliver at minimum two simultaneous connections, in any combination of data, voice and fax, over a single line. Multiple devices can be attached to the line, used as needed; that means an ISDN line can take care of what were expected to be most people's complete communications needs at a much higher transmission rate, without forcing the purchase of multiple analog phone lines.
It refers to integrated switching and transmission in that telephone switching and carrier wave transmission are integrated rather than separate as in earlier technology. The entry level interface to ISDN is the Basic Rate Interface, a 128 kbit/s service delivered over a pair of standard telephone copper wires; the 144 kbit/s overall payload rate is divided into two 64 kbit/s bearer channels and one 16 kbit/s signaling channel. This is sometimes referred to as 2B+D; the interface specifies the following network interfaces: The U interface is a two-wire interface between the exchange and a network terminating unit, the demarcation point in non-North American networks. The T interface is a serial interface between a computing device and a terminal adapter, the digital equivalent of a modem; the S interface is a four-wire bus. The R interface defines the point between a non-ISDN device and a terminal adapter which provides translation to and from such a device. BRI-ISDN is popular in Europe but is much less common in North America.
It is common in Japan — where it is known as INS64. The other ISDN access available is the Primary Rate Interface, carried over T-carrier with 24 time slots in North America, over E-carrier with 32 channels in most other countries; each channel provides transmission at a 64 kbit/s data rate. With the E1 carrier, the available channels are divided into 30 bearer channels, one data channel, one timing and alarm channel; this scheme is referred to as 30B+2D. In North America, PRI service is delivered via T1 carriers with only one data channel referred to as 23B+D, a total data rate of 1544 kbit/s. Non-Facility Associated Signalling allows two or more PRI circuits to be controlled by a single D channel, sometimes called 23B+D + n*24B. D-channel backup allows for a second D channel in case the primary fails. NFAS is used on a Digital Signal 3. PRI-ISDN is popular throughout the world for connecting private branch exchanges to the public switched telephone network. Though many network professionals use the term ISDN to refer to the lower-bandwidth BRI circuit, in North America BRI is uncommon whilst PRI circuits serving PBXs are commonplace.
The bearer channel is a standard 64 kbit/s voice channel of 8 bits sampled at 8 kHz with G.711 encoding. B-channels can be used to carry data, since they are nothing more than digital channels; each one of these channels is known as a DS0. Most B channels can carry a 64 kbit/s signal, but some were limited to 56K because they traveled over RBS lines; this has since become less so. X.25 can be carried over the B or D channels of a BRI line, over the B channels of a PRI line. X.25 over the D channel is used at many point-of-sale terminals because it eliminates the modem setup, because it connects to the central system over a B channel, thereby eliminating the need for modems and making much better use of the central system's telephone lines. X.25 was part of an ISDN protocol
Salzburg is a state of Austria. It is named Land Salzburg, colloquially Salzburgerland, to distinguish it from its eponymous capital Salzburg city and as such is the only state to be named after its capital. By its centuries-long history as an independent Prince-Bishopric, Salzburg's tradition differs from the other Austrian lands. Salzburg state stretches along its primary river, the Salzach running from the Central Eastern Alps in the south – reaching a height of 3,657 metres at the mountain Großvenediger – down into the Alpine foothills in the north, with an area of 7,156 km2, it is located in the north of the country, close to the border with the German state of Bavaria. It is surrounded by the Austrian lands of Upper Austria in the northeast, by Styria in the east, by Carinthia in the south as well as by Tyrol, South Tyrol and East Tyrol in the southwest. With 529,085 inhabitants, it is one of the country's smaller states in terms of population. Running through the south are the main ranges of the Alpine divide with numerous three-thousanders.
The Dachstein massif and the Berchtesgaden Alps ranges of the Northern Limestone Alps border Salzburg Land to the east and north. The state is traditionally subdivided in congruent with its political districts. In the northern part: Flachgau, the flat Salzburg Basin around the confluence of Salzach and Saalach, stretching from the slopes of the Salzkammergut Mountains in the east to the Untersberg massif and the Chiemgau Alps in the west. Tennengau, named after the Tennen Mountains, including the broad Salzach Valley south of Salzburg and the surrounding ranges of the Limestone Alps; the southern, mountainous part is divided into: Pinzgau in the southwest, Pongau on Salzach and Enns, Lungau in the southeast, separated by the Niedere Tauern range. Salzburg municipalities with town privileges: Wals-Siezenheim, a common municipality with about 12,000 inhabitants, is known as'Austria's largest village'. Salt has played an important role in the region's development. Independence from Bavaria was secured in the late 14th century.
The Archbishopric of Salzburg was an independent prince-bishopric and State of the Holy Roman Empire until German Mediatisation in 1813. The territory was secularized and, as the Electorate of Salzburg, given as compensation to Ferdinand III, former Grand Duke of Tuscany, the brother of Emperor Francis II. Following the Austrian defeat at Austerlitz in 1805, Salzburg was annexed by Austria as compensation for the loss of Tyrol to the Kingdom of Bavaria, Ferdinand was transferred to the Grand Duchy of Würzburg. After Austria's defeat in 1809, the province was handed over to Bavaria in 1810. In 1816, following the defeat of Napoleon and the provision of adequate compensation to Bavaria at the Congress of Vienna, it was returned to Austria with the exception of the north-western Rupertiwinkel which remained Bavarian; the Salzburger Land was administered as the department of Salzach from Linz, the capital of Upper Austria. In 1849 the Duchy of Salzburg was established as a crown land of the Austrian Empire and, after 1866, Austria-Hungary.
Salzburg participated as part of the Austro-Hungarian Empire. 49,000 Salzburgers were called to arms. In 1918 after World War I, the Duchy of Salzburg was dissolved and replaced with the State of Salzburg, as a component part of German Austria and subsequently of the First Republic of Austria, the separate state, mandated by the Allied powers. After the plebiscite of 1938, Salzburg state and all the territory of Austria was annexed to the Third Reich. After the defeat of Nazi Germany in 1945, the Allies occupied the territory of Austria, being recognized as an independent territory under their rule. Salzburg was occupied by the United States. In 1955 Austria was again declared independent of the Allies and Salzburg was once again one of the reconstituted federal states of the second Republic Austria. Salzburg adopted its current state constitution in 1999; the state government is headed by a Landeshauptmann, elected by a majority in the Landtag parliament. State elections are held every five years.
After World War II, most state governments were led by the conservative Austrian People's Party. The ÖVP politician Josef Klaus Chancellor of Austria, served as Landeshauptmann from 1949 to 1961. In 2004 Gabi Burgstaller became the first Social Democratic Salzburg governor; the last results, in May 2013 were: The elected Salzburg Landeshauptmann is Wilfried Haslauer, chairing a coalition government of ÖVP, Greens and Team Stronach ministers. The current president of the Salzburg Landtag is his party fellow Brigitta Pallauf. Economy Tourism Employment market Municipality administration Education Internal affairs Fire departments Public safety Governor's office European affairs. Conservation Environmentalism Water protection Trade Regional development Building law. Finance State properties and interests Public health and hospitals. Hans Mayr: Transport, housing Martina Berthold: Childcare, adult education, research, youth, family affairs, intergenerational relationships, migration, women's affairs, equal opport
Eutelsat S. A. is a European satellite operator. Providing coverage over the entire European continent, the Middle East, Africa and the Americas, it is the world's third largest satellite operator in terms of revenues. Eutelsat's satellites are used for broadcasting nearly 7,000 television stations, of which 1,400 are in HD, 1,100 radio stations to over 274 million cable and satellite homes, they serve requirements for TV contribution services, corporate networks, mobile communications, Internet backbone connectivity and broadband access for terrestrial, maritime and in-flight applications. Eutelsat is headquartered in Paris. Eutelsat Communications Chief Executive Officer is Rodolphe Belmer. In October 2017, Eutelsat acquired NOORSAT, one of the leading satellite service providers in the Middle East, from Bahrain's Orbit Holding Group. NOORSAT is the premier distributor of Eutelsat capacity in the Middle East, serving blue-chip customers and providing services for over 300 TV channels exclusively from Eutelsat's market-leading Middle East and North Africa neighbourhoods at 7/8° West and 25.5° East.
The European Telecommunications Satellite Organization was set up in 1977 by 17 European countries as an intergovernmental organisation. Its role was to operate a satellite-based telecommunications infrastructure for Europe; the Convention establishing the European Telecommunications Satellite Organization EUTELSAT was opened for signature in July 1982 and entered into force on 1 September 1985. In 1982 Eutelsat decided to start operations of its first TV channel on the Orbital Test Satellite in cooperation with ESA; this was the first satellite based direct-to-home TV channel launched in Europe. In 1983 Eutelsat launched its first satellite to be used for telecommunications and TV distribution Initially established to address satellite telecommunications demand in Western Europe, Eutelsat developed its infrastructure to expand coverage to additional services and markets, such as Central and Eastern Europe in 1989, the Middle East, the African continent, large parts of Asia and the Americas from the 1990s.
Eutelsat was the first satellite operator in Europe to broadcast television channels direct-to-home. It developed its premium neighbourhood of five Hot Bird satellites in the mid-1990s to offer capacity that would be able to attract hundreds of channels to the same orbital location, appealing to widespread audiences for consumer satellite TV. With the general liberalisation of the telecommunications sector in Europe, EUTELSAT's assets and operational activities were transferred to a private company called Eutelsat S. A. established for this purpose in July 2001. The structure role and activities of the new intergovernmental organisation EUTELSAT IGO evolved. To this day, the main purpose of EUTELSAT IGO has been to ensure that Eutelsat S. A. observes the Basic Principles set forth in the EUTELSAT Amended Convention entered into force in November 2002. These Basic Principles refer to public service/universal service obligations, pan European coverage by the satellite system, non-discrimination and fair competition.
The Executive Secretary of EUTELSAT IGO participates in all meetings of the Board of Directors of Eutelsat Communications S. A. and Eutelsat S. A. as an observer to the Board. In April 2005, the principal shareholders of Eutelsat S. A. grouped their investment in a new entity, now the holding company of the Group owning 95.2% of Eutelsat S. A. on October 6, 2005. It owns 96.0% of Eutelsat S. A. On July 31, 2013, Eutelsat Communications announced the 100% acquisition of Satélites Mexicanos, S. A. de C. V. for $831 million in cash plus assumption of $311 million in Satmex debt, pending government and regulatory approvals. The transaction was finalized on January 2, 2014. Based in Mexico, Satmex operates three satellites at contiguous positions, 113° West, 114.9° West and 116.8° West that cover 90% of the population of the Americas. In December 2015, the company announced a partnership with Facebook to launch an internet satellite over Africa by 2016 where Facebook lease all of a satellite's high-throughput Ka-band capacity, however the satellite was destroyed during launch preparations.
Hybrid Satellite OTT Solutions In September 2018, Eutelsat launched Eutelsat CIRRUS, a new turnkey content delivery solution which enables broadcasters to deliver content to satellite and OTT screens and offer their audiences a seamless, multi-screen experience. Combining the wide reach of traditional DTH, with next-generation features, broadcasters can deliver an enriched viewer experience through live channel broadcasting, channel numbering, programme information, content security, subscriber management and set-top box management. Viewers can watch content on screens and tablets, access multiple programmes and rewind and view detailed programme information. Eutelsat sells capacity on 37 satellites located in geosynchronous orbit between 133 degrees West and 174 degrees East. On 1 March 2012, Eutelsat changed the names of its satellites; the group's satellites take the Eutelsat name, with the relevant figure for their orbital position and a letter indicating their order of arrival at that position.
On 21 May 2014, Eutelsat Americas aligned its satellite names with the Eutelsat brand. Guy Lebègue, « Eutelsat II: OK For West-to-East Service! », in Revue aerospatiale, n°73, November 1990. Eutelsat portal Official Website Tooway, Eutelsat's consumer broadband service
An optical fiber is a flexible, transparent fiber made by drawing glass or plastic to a diameter thicker than that of a human hair. Optical fibers are used most as a means to transmit light between the two ends of the fiber and find wide usage in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths than electrical cables. Fibers are used instead of metal wires. Fibers are used for illumination and imaging, are wrapped in bundles so they may be used to carry light into, or images out of confined spaces, as in the case of a fiberscope. Specially designed fibers are used for a variety of other applications, some of them being fiber optic sensors and fiber lasers. Optical fibers include a core surrounded by a transparent cladding material with a lower index of refraction. Light is kept in the core by the phenomenon of total internal reflection which causes the fiber to act as a waveguide. Fibers that support many propagation paths or transverse modes are called multi-mode fibers, while those that support a single mode are called single-mode fibers.
Multi-mode fibers have a wider core diameter and are used for short-distance communication links and for applications where high power must be transmitted. Single-mode fibers are used for most communication links longer than 1,000 meters. Being able to join optical fibers with low loss is important in fiber optic communication; this is more complex than joining electrical wire or cable and involves careful cleaving of the fibers, precise alignment of the fiber cores, the coupling of these aligned cores. For applications that demand a permanent connection a fusion splice is common. In this technique, an electric arc is used to melt the ends of the fibers together. Another common technique is a mechanical splice, where the ends of the fibers are held in contact by mechanical force. Temporary or semi-permanent connections are made by means of specialized optical fiber connectors; the field of applied science and engineering concerned with the design and application of optical fibers is known as fiber optics.
The term was coined by Indian physicist Narinder Singh Kapany, acknowledged as the father of fiber optics. Guiding of light by refraction, the principle that makes fiber optics possible, was first demonstrated by Daniel Colladon and Jacques Babinet in Paris in the early 1840s. John Tyndall included a demonstration of it in his public lectures in London, 12 years later. Tyndall wrote about the property of total internal reflection in an introductory book about the nature of light in 1870:When the light passes from air into water, the refracted ray is bent towards the perpendicular... When the ray passes from water to air it is bent from the perpendicular... If the angle which the ray in water encloses with the perpendicular to the surface be greater than 48 degrees, the ray will not quit the water at all: it will be reflected at the surface.... The angle which marks the limit where total reflection begins is called the limiting angle of the medium. For water this angle is 48°27′, for flint glass it is 38°41′, while for diamond it is 23°42′.
In the late 19th and early 20th centuries, light was guided through bent glass rods to illuminate body cavities. Practical applications such as close internal illumination during dentistry appeared early in the twentieth century. Image transmission through tubes was demonstrated independently by the radio experimenter Clarence Hansell and the television pioneer John Logie Baird in the 1920s. In the 1930s, Heinrich Lamm showed that one could transmit images through a bundle of unclad optical fibers and used it for internal medical examinations, but his work was forgotten. In 1953, Dutch scientist Bram van Heel first demonstrated image transmission through bundles of optical fibers with a transparent cladding; that same year, Harold Hopkins and Narinder Singh Kapany at Imperial College in London succeeded in making image-transmitting bundles with over 10,000 fibers, subsequently achieved image transmission through a 75 cm long bundle which combined several thousand fibers. Their article titled "A flexible fibrescope, using static scanning" was published in the journal Nature in 1954.
The first practical fiber optic semi-flexible gastroscope was patented by Basil Hirschowitz, C. Wilbur Peters, Lawrence E. Curtiss, researchers at the University of Michigan, in 1956. In the process of developing the gastroscope, Curtiss produced the first glass-clad fibers. A variety of other image transmission applications soon followed. Kapany coined the term fiber optics, wrote a 1960 article in Scientific American that introduced the topic to a wide audience, wrote the first book about the new field; the first working fiber-optical data transmission system was demonstrated by German physicist Manfred Börner at Telefunken Research Labs in Ulm in 1965, followed by the first patent application for this technology in 1966. NASA used fiber optics in the television cameras. At the time, the use in the cameras was classified confidential, employees handling the cameras had to be supervised by someone with an appropriate security clearance. Charles K. Kao and George A. Hockham of the British company Standard Telephones and Cables were the first, in 1965, to promote the idea that the attenuation in optical fibers could be reduced below 20 decibels per kilometer, making fibers a practical communication medium.
They proposed th