The earlyhistory of radio is thehistory of technology that produces and usesradio instruments that useradio waves. Within thetimeline of radio, many people contributed theory and inventions in what becameradio. Radio development began as "wireless telegraphy". Later radio history increasingly involves matters ofbroadcasting.
In an 1864 presentation, published in 1865,James Clerk Maxwell proposed theories ofelectromagnetism and mathematical proofs demonstrating that light, radio and x-rays were all types of electromagnetic waves propagating throughfree space.[1][2][3][4][5]
Between 1886 and 1888Heinrich Rudolf Hertz published the results of experiments wherein he was able to transmit electromagnetic waves (radio waves) through the air, proving Maxwell's electromagnetic theory.[6][7]
After their discovery many scientists and inventors experimented with transmitting and detecting "Hertzian waves" (it would take almost 20 years for the term "radio" to be universally adopted for this type of electromagnetic radiation).[8] Maxwell's theory showing that light and Hertzian electromagnetic waves were the same phenomenon at different wavelengths led "Maxwellian" scientists such as John Perry,Frederick Thomas Trouton and Alexander Trotter to assume they would be analogous to optical light.[9][10]
Following Hertz' untimely death in 1894, British physicist and writerOliver Lodge presented a widely covered lecture on Hertzian waves at theRoyal Institution on June 1 of the same year.[11] Lodge focused on the optical qualities of the waves and demonstrated how to transmit and detect them (using an improved variation of French physicistÉdouard Branly's detector Lodge named the "coherer").[12] Lodge further expanded on Hertz' experiments showing how these new waves exhibited like lightrefraction,diffraction,polarization,interference andstanding waves,[13] confirming that Hertz' waves and light waves were both forms of Maxwell'selectromagnetic waves. During part of the demonstration the waves were sent from the neighboringClarendon Laboratory building, and received by apparatus in the lecture theater.[14]
After Lodge's demonstrations researchers pushed their experiments further down the electromagnetic spectrum towards visible light to further explore thequasioptical nature at these wavelengths.[15]Oliver Lodge andAugusto Righi experimented with 1.5 and 12 GHz microwaves respectively, generated by small metal ball spark resonators.[13] Russian physicistPyotr Lebedev in 1895 conducted experiments in the 50 GHz (6 millimeter) range.[13] Bengali Indian physicistJagadish Chandra Bose conducted experiments at wavelengths of 60 GHz (5 millimeter) and inventedwaveguides,horn antennas, andsemiconductorcrystal detectors for use in his experiments.[16] He would later write an essay, "Adrisya Alok" ("Invisible Light") on how in November 1895 he conducted a public demonstration at the Town Hall ofKolkata,India using millimeter-range-wavelength microwaves to trigger detectors that ignited gunpowder and rang a bell at a distance.[17]
Between 1890 and 1892 physicists such as John Perry,Frederick Thomas Trouton andWilliam Crookes proposed electromagnetic or Hertzian waves as a navigation aid or means of communication, with Crookes writing on the possibilities of wirelesstelegraphy based on Hertzian waves in 1892.[18] Among physicists, what were perceived as technical limitations to using these new waves, such as delicate equipment, the need for large amounts of power to transmit over limited ranges, and its similarity to already existent optical light transmitting devices, lead them to a belief that applications were very limited. The Serbian American engineerNikola Tesla considered Hertzian waves relatively useless for long range transmission since "light" could not transmit further thanline of sight.[19] There was speculation that this fog and stormy weather penetrating "invisible light" could be used in maritime applications such as lighthouses.[18] The London journalThe Electrician (December 1895) commented on Bose's achievements, saying "we may in time see the whole system of coast lighting throughout the navigable world revolutionized by an Indian Bengali scientist working single handed[ly] in our Presidency College Laboratory."[20]
In 1895, adapting the techniques presented in Lodge's published lectures, Russian physicistAlexander Stepanovich Popov built alightning detector that used a coherer based radio receiver.[21] He presented it to the Russian Physical and Chemical Society on May 7, 1895.
In 1894, the young Italian inventorGuglielmo Marconi began working on the idea of building long-distance wireless transmission systems based on the use of Hertzian waves (radio waves), a line of inquiry that he noted other inventors did not seem to be pursuing.[22] Marconi read through the literature and used the ideas of others who were experimenting with radio waves but did a great deal to develop devices such as portable transmitters and receiver systems that could work over long distances,[22] turning what was essentially a laboratory experiment into a useful communication system.[23] By August 1895, Marconi was field testing his system but even with improvements he was only able to transmit signals up to one-half mile, a distance Oliver Lodge had predicted in 1894 as the maximum transmission distance for radio waves. Marconi raised the height of his antenna and hit upon the idea of grounding his transmitter and receiver. With these improvements the system was capable of transmitting signals up to 2 miles (3.2 km) and over hills.[24] This apparatus proved to be the first engineering-complete, commercially successfulradio transmission system[25][26][27] and Marconi went on to file British patent GB189612039A,Improvements in transmitting electrical impulses and signals and in apparatus there-for, in 1896. This patent was granted in the UK on 2 July 1897.[28]
In 1897, Marconi established a radio station on theIsle of Wight, England and opened his "wireless" factory in the formersilk-works at Hall Street,Chelmsford, England, in 1898, employing around 60 people.
On 12 December 1901, using a 500-foot (150 m) kite-supported antenna for reception—signals transmitted by the company's new high-power station atPoldhu, Cornwall, Marconi transmitted a message across the Atlantic Ocean toSignal Hill inSt. John's,Newfoundland.[29][30][31][32]
Marconi began to build high-powered stations on both sides of the Atlantic to communicate with ships at sea. In 1904, he established a commercial service to transmit nightly news summaries to subscribing ships, which could incorporate them into their on-board newspapers. A regular transatlantic radio-telegraph service was finally begun on 17 October 1907[33][34] betweenClifden, Ireland, andGlace Bay, but even after this the company struggled for many years to provide reliable communication to others.
Marconi's apparatus is also credited with saving the 700 people who survived the tragicTitanic disaster.[35]
In the late 1890s, Canadian-American inventorReginald Fessenden came to the conclusion that he could develop a far more efficient system than the spark-gap transmitter and coherer receiver combination.[36][37] To this end he worked on developing a high-speed alternator (referred to as "an alternating-current dynamo") that generated "pure sine waves" and produced "a continuous train of radiant waves of substantially uniform strength", or, in modern terminology, acontinuous-wave (CW) transmitter.[38] While working for theUnited States Weather Bureau onCobb Island, Maryland, Fessenden researched using this setup for audio transmissions via radio. By fall of 1900, he successfully transmitted speech over a distance of about 1.6 kilometers (one mile),[39] which appears to have been the first successful audio transmission using radio signals.[40][41] Although successful, the sound transmitted was far too distorted to be commercially practical.[42] According to some sources, notably Fessenden's wife Helen's biography, onChristmas Eve 1906,Reginald Fessenden used anAlexanderson alternator and rotaryspark-gap transmitter to make the first radio audio broadcast, fromBrant Rock, Massachusetts. Ships at sea heard a broadcast that included Fessenden playingO Holy Night on theviolin and reading a passage from theBible.[43][44]
Around the same time American inventorLee de Forest experimented with anarc transmitter, which unlike the discontinuous pulses produced by spark transmitters, created steady "continuous wave" signal that could be used foramplitude modulated (AM) audio transmissions. In February 1907 he transmitted electronictelharmonium music from his laboratory station in New York City.[45] This was followed by tests that included, in the fall,Eugenia Farrar singing "I Love You Truly".[46] In July 1907 he made ship-to-shore transmissions by radiotelephone—race reports for the Annual Inter-Lakes Yachting Association (I-LYA) Regatta held onLake Erie—which were sent from the steam yachtThelma to his assistant, Frank E. Butler, located in the Fox's Dock Pavilion onSouth Bass Island.[47]
The Dutch companyNederlandsche Radio-Industrie and its owner-engineer,Hanso Idzerda, made its first regular entertainment radio broadcast over stationPCGG from its workshop inThe Hague on 6 November 1919. The company manufactured both transmitters and receivers. Its popular program was broadcast four nights per week using narrow-band FM transmissions on 670 metres (448 kHz),[48] until 1924 when the company ran into financial trouble.
Regular entertainment broadcasts began inArgentina, pioneered byEnrique Telémaco Susini and his associates. At 9 pm on August 27, 1920, Sociedad Radio Argentina aired a live performance of Richard Wagner's operaParsifal from the Coliseo Theater in downtownBuenos Aires. Only about twenty homes in the city had receivers to tune in this program.
On 31 August 1920 theDetroit News began publicized daily news and entertainment "Detroit News Radiophone" broadcasts, originally as licensed amateur station 8MK, then later as WBL andWWJ inDetroit, Michigan.
Union College in Schenectady,New York began broadcasting on October 14, 1920, over2ADD, an amateur station licensed to Wendell King, anAfrican-American student at the school.[49] Broadcasts included a series of Thursday night concerts initially heard within a 100-mile (160 km) radius and later for a 1,000-mile (1,600 km) radius.[49][50]
In 1922 regular audio broadcasts for entertainment began in the UK from theMarconi Research Centre2MT atWrittle nearChelmsford, England.
In early radio, and to a limited extent much later, the transmission signal of the radio station was specified in meters, referring to thewavelength, the length of the radio wave. This is the origin of the termslong wave,medium wave, andshort wave radio.[51] Portions of the radio spectrum reserved for specific purposes were often referred to by wavelength: the40-meter band, used foramateur radio, for example. The relation between wavelength and frequency is reciprocal: the higher the frequency, the shorter the wave, and vice versa.
As equipment progressed, precise frequency control became possible; early stations often did not have a precise frequency, as it was affected by the temperature of the equipment, among other factors. Identifying a radio signal by its frequency rather than its length proved much more practical and useful, and starting in the 1920s this became the usual method of identifying a signal, especially in the United States. Frequencies specified in number of cycles per second (kilocycles, megacycles) were replaced by the more specific designation ofhertz (cycles per second) about 1965.
Using variouspatents, theBritish Marconi company was established in 1897 by Guglielmo Marconi and began communication betweencoast radio stations and ships at sea.[52] A year after, in 1898, they successfully introduced their first radio station in Chelmsford. This company, along with its subsidiariesCanadian Marconi andAmerican Marconi, had a stranglehold on ship-to-shore communication. It operated much the wayAmerican Telephone and Telegraph operated until 1983, owning all of its equipment and refusing to communicate with non-Marconi equipped ships. Many inventions improved the quality of radio, and amateurs experimented with uses of radio, thus planting the first seeds of broadcasting.
The companyTelefunken was founded on May 27, 1903, as "Telefunken society for wireless telefon" ofSiemens & Halske (S & H) and theAllgemeine Elektrizitäts-Gesellschaft (General Electricity Company) as joint undertakings for radio engineering in Berlin.[53] It continued as a joint venture ofAEG andSiemens AG, until Siemens left in 1941. In 1911,Kaiser Wilhelm II sent Telefunken engineers toWest Sayville,New York to erect three 600-foot (180-m) radio towers there. Nikola Tesla assisted in the construction. A similar station was erected inNauen, creating the only wireless communication between North America and Europe.
The invention of amplitude-modulated (AM) radio, which allows more closely spaced stations to simultaneously send signals (as opposed to spark-gap radio, where each transmission occupies a wide bandwidth) is attributed toReginald Fessenden,Valdemar Poulsen andLee de Forest.
The most common type of receiver before vacuum tubes was thecrystal set, although some early radios used some type of amplification through electric current or battery. Inventions of thetriode amplifier,motor-generator, anddetector enabled audio radio. The use ofamplitude modulation (AM), by which soundwaves can be transmitted over a continuous-wave radio signal of narrow bandwidth (as opposed to spark-gap radio, which sent rapid strings of damped-wave pulses that consumed much bandwidth and were only suitable for Morse-code telegraphy) was pioneered by Fessenden, Poulsen and Lee de Forest.[54]
The art and science of crystal sets is still pursued as a hobby in the form of simple un-amplified radios that 'runs on nothing, forever'. They are used as a teaching tool by groups such as theBoy Scouts of America to introduce youngsters to electronics and radio. As the only energy available is that gathered by the antenna system, loudness is necessarily limited.
During the mid-1920s, amplifyingvacuum tubes revolutionizedradio receivers andtransmitters.John Ambrose Fleming developed a vacuum tubediode.Lee de Forest placed a screen, added a"grid" electrode, creating thetriode.[55]
Early radios ran the entire power of the transmitter through acarbon microphone. In the 1920s, theWestinghouse company bought Lee de Forest's andEdwin Armstrong's patent. During the mid-1920s, Amplifyingvacuum tubes revolutionizedradio receivers and transmitters. Westinghouse engineers developed a more modern vacuum tube.
The first radios still required batteries, but in 1926 the "battery eliminator" was introduced to the market. This tube technology allowed radios to be powered through the grid instead. They still required batteries to heat up the vacuum-tube filaments, but after the invention ofindirectly heated vacuum tubes, the first completely battery free radios became available in 1927.[56]
In 1929 a new screen grid tube called UY-224 was introduced, an amplifier designed to operate directly on alternating current.[57]
A problem with the early radios was fading stations and fluctuating volume. The invention of thesuperheterodyne receiver solved this problem, and the first radios with a heterodyne radio receiver went for sale in 1924. But it was costly, and the technology was shelved while waiting for the technology to mature, and in 1929 the Radiola 66 and Radiola 67 went for sale.[58][59][60]
In the early days one had to use headphones to listen to radio. Later loudspeakers in the form of a horn of the type used by phonographs, equipped with a telephone receiver, became available. But the sound quality was poor. In 1926 the first radios with electrodynamic loudspeakers went for sale, which improved the quality significantly. At first the loudspeakers were separated from the radio, but soon radios would come with a built-in loudspeaker.[61]
Other inventions related to sound included the automatic volume control (AVC), first commercially available in 1928.[62] In 1930 a tone control knob was added to the radios. This allowed listeners to improve imperfect broadcasting.[63]
Themagnetic cartridge, which was introduced in the mid 20's, greatly improved the broadcasting of music. When playing music from a phonograph before the magnetic cartridge, a microphone had to be placed close to a horn loudspeaker. The invention allowed the electric signals to be amplified and then fed directly to thebroadcast transmitter.[64]
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Following development oftransistor technology,bipolar junction transistors led to the development of thetransistor radio. In 1954, the Regency company introduced a pocket transistor radio, theTR-1, powered by a "standard 22.5 V Battery." In 1955, the newly formedSony company introduced its first transistorized radio, theTR-55.[65] It was small enough to fit in avest pocket, powered by a small battery. It was durable, because it had no vacuum tubes to burn out. In 1957, Sony introduced the TR-63, the first mass-produced transistor radio, leading to the mass-market penetration of transistor radios.[66] Over the next 20 years, transistors replaced tubes almost completely except for high-powertransmitters.
By the mid-1960s, theRadio Corporation of America (RCA) were usingmetal–oxide–semiconductor field-effect transistors (MOSFETs) in their consumer products, includingFM radio, television andamplifiers.[67]Metal–oxide–semiconductor (MOS)large-scale integration (LSI) provided a practical and economic solution for radio technology, and was used inmobile radio systems by the early 1970s.[68]
The first integrated circuit (IC) radio, P1740 byGeneral Electric, became available in 1966.[69]
The first car radio was introduced in 1922, but it was so large that it took up too much space in the car.[70] The first commercial car radio that could easily be installed in most cars went for sale in 1930.[71][72]
Telegraphy did not go away on radio. Instead, the degree of automation increased. On land-lines in the 1930s,teletypewriters automated encoding, and were adapted to pulse-code dialing to automate routing, a service calledtelex. For thirty years, telex was the cheapest form of long-distance communication, because up to 25 telex channels could occupy the same bandwidth as one voice channel. For business and government, it was an advantage that telex directly produced written documents.
Telex systems were adapted to short-wave radio by sending tones oversingle sideband.CCITT R.44 (the most advanced pure-telex standard) incorporated character-level error detection and retransmission as well as automated encoding and routing. For many years, telex-on-radio (TOR) was the only reliable way to reach some third-world countries. TOR remains reliable, though less-expensive forms of e-mail are displacing it. Many national telecom companies historically ran nearly pure telex networks for their governments, and they ran many of these links over short wave radio.
Documents including maps and photographs went byradiofax, or wireless photoradiogram, invented in 1924 byRichard H. Ranger ofRadio Corporation of America (RCA). This method prospered in the mid-20th century and faded late in the century.
One of the first developments in the early 20th century was that aircraft used commercial AM radio stations for navigation, AM stations are still marked on U.S. aviation charts.Radio navigation played an important role during war time, especially in World War II. Before the discovery of the crystal oscillator, radio navigation had many limits.[73] However, as radio technology expanding, navigation is easier to use, and it provides a better position. Although there are many advantages, the radio navigation systems often comes with complex equipment such as the radio compass receiver, compass indicator, or the radar plan position indicator. All of these require users to obtain certain knowledge.
In the 1960sVOR systems became widespread. In the 1970s,LORAN became the premier radio navigation system. Soon, the US Navy experimented withsatellite navigation. In 1987, theGlobal Positioning System (GPS) constellation ofsatellites was launched; it was followed by otherGNSS systems likeGlonass,BeiDou andGalileo.
In 1933,FM radio was patented by inventorEdwin H. Armstrong.[74] FM usesfrequency modulation of the radio wave to reducestatic andinterference from electrical equipment and the atmosphere. In 1937,W1XOJ, the first experimental FM radio station after Armstrong'sW2XMN in Alpine, New Jersey, was granted a construction permit by the USFederal Communications Commission (FCC).
After World War II,FM radio broadcasting was introduced in Germany. At a meeting inCopenhagen in 1948, a newwavelength plan was set up for Europe. Because of the recent war, Germany (which did not exist as a state and so was not invited) was only given a small number ofmedium-wave frequencies, which were not very good for broadcasting. For this reason Germany began broadcasting on UKW ("Ultrakurzwelle", i.e. ultra short wave, nowadays calledVHF) which was not covered by the Copenhagen plan. After someamplitude modulation experience with VHF, it was realized that FM radio was a much better alternative for VHF radio than AM. Because of this history, FM radio is still referred to as "UKW Radio" in Germany. Other European nations followed a bit later, when the superior sound quality of FM and the ability to run many more local stations because of the more limited range of VHF broadcasts were realized.
In the 1930s, regularanalog television broadcasting began in some parts of Europe and North America. By the end of the decade there were roughly 25,000 all-electronic television receivers in existence worldwide, the majority of them in the UK. In the US, Armstrong's FM system was designated by the FCC to transmit and receive television sound.
By 1963,color television was being broadcast commercially (though not all broadcasts or programs were in color), and the first (radio)communication satellite,Telstar, was launched. In the 1970s,
In 1947 AT&T commercialized theMobile Telephone Service. From its start in St. Louis in 1946, AT&T then introduced Mobile Telephone Service to one hundred towns and highway corridors by 1948. Mobile Telephone Service was a rarity with only 5,000 customers placing about 30,000 calls each week. Because only three radio channels were available, only three customers in any given city could make mobile telephone calls at one time.[76] Mobile Telephone Service was expensive, costing US$15 per month, plus $0.30–0.40 per local call, equivalent to (in 2012 US dollars) about $176 per month and $3.50–4.75 per call.[77] TheAdvanced Mobile Phone System analog mobile phone system, developed byBell Labs, was introduced in the Americas in 1978,[78][79][80] gave much more capacity. It was the primary analog mobile phone system in North America (and other locales) through the 1980s and into the 2000s.
The development ofmetal–oxide–semiconductor (MOS)large-scale integration (LSI) technology,information theory andcellular networking led to the development of affordablemobile communications.[81] TheAdvanced Mobile Phone System analog mobile phone system, developed byBell Labs and introduced in theAmericas in 1978,[78][79][80] gave much more capacity. It was the primary analog mobile phone system inNorth America (and other locales) through the 1980s and into the 2000s.
The British government and the state-owned postal services found themselves under massive pressure from the wireless industry (including telegraphy) and early radio adopters to open up to the new medium. In an internal confidential report from February 25, 1924, theImperial Wireless Telegraphy Committee stated:
When radio was introduced in the early 1920s, many predicted it would kill thephonograph record industry. Radio was a free medium for the public to hear music for which they would normally pay. While some companies saw radio as a new avenue for promotion, others feared it would cut into profits from record sales and live performances. Many record companies would not license their records to be played over the radio, and had their major stars sign agreements that they would not perform on radio broadcasts.[83][84]
Indeed, the music recording industry had a severe drop in profits after the introduction of the radio. For a while, it appeared as though radio was a definite threat to the record industry. Radio ownership grew from two out of five homes in 1931 to four out of five homes in 1938. Meanwhile, record sales fell from $75 million in 1929 to $26 million in 1938 (with a low point of $5 million in 1933), though the economics of the situation were also affected by theGreat Depression.[85]
The copyright owners were concerned that they would see no gain from the popularity of radio and the 'free' music it provided. What they needed to make this new medium work for them already existed in previous copyright law. The copyright holder for a song had control over all public performances 'for profit.' The problem now was proving that the radio industry, which was just figuring out for itself how to make money from advertising and currently offered free music to anyone with a receiver, was making a profit from the songs.
Thetest case was againstBamberger's Department Store inNewark, New Jersey in 1922. The store was broadcasting music from its store on the radio station WOR. No advertisements were heard, except at the beginning of the broadcast which announced "L. Bamberger and Co., One of America's Great Stores, Newark, New Jersey." It was determined through this and previous cases (such as the lawsuit against Shanley's Restaurant) that Bamberger was using the songs for commercial gain, thus making it a public performance for profit, which meant the copyright owners were due payment.
With this ruling theAmerican Society of Composers, Authors and Publishers (ASCAP) began collecting licensing fees from radio stations in 1923. The beginning sum was $250 for all music protected under ASCAP, but for larger stations the price soon ballooned to $5,000. Edward Samuels reports in his bookThe Illustrated Story of Copyright that "radio and TV licensing represents the single greatest source of revenue for ASCAP and its composers […] and [a]n average member of ASCAP gets about $150–$200 per work per year, or about $5,000-$6,000 for all of a member's compositions." Not long after the Bamberger ruling, ASCAP had to once again defend their right to charge fees, in 1924. The Dill Radio Bill would have allowed radio stations to play music without paying and licensing fees to ASCAP or any other music-licensing corporations. The bill did not pass.[86]
Radio technology was first used for ships to communicate at sea. To ensure safety, theWireless Ship Act of 1910 marks the first time the U.S. government implies regulations on radio systems on ships.[87] This act requires ships to have a radio system with a professional operator if they want to travel more than 200 miles offshore or have more than 50 people on board. However, this act had many flaws including the competition ofradio operators including the two majors company (British and American Marconi). They tended to delay communication for ships that used their competitor's system. This contributed to the tragic incident of the sinking of theTitanic in 1912.
In 1912, distress calls to aid the sinkingTitanic were met with a large amount of interfering radio traffic, severely hampering the rescue effort. Subsequently, the US government passed theRadio Act of 1912 to help mitigate the repeat of such a tragedy. The act helps distinguish between normal radio traffic and (primarily maritime) emergency communication, and specifies the role of government during such an emergency.[88]
TheRadio Act of 1927 gave theFederal Radio Commission the power to grant and deny licenses, and to assign frequencies and power levels for each licensee. In 1928 it began requiring licenses of existing stations and setting controls on who could broadcast from where on what frequency and at what power. Some stations could not obtain a license and ceased operations. In section 29, the Radio Act of 1927 mentioned that the content of the broadcast should be freely present, and the government cannot interfere with this.[89]
The introduction of theCommunications Act of 1934 led to the establishment of the Federal Communications Commissions (FCC). The FCC's responsibility is to control the industry including "telephone, telegraph, and radio communications."[90] Under this Act, all carriers have to keep records of authorized interference and unauthorized interference. This Act also supports the President in time of war. If the government needs to use the communication facilities in time of war, they are allowed to.
TheTelecommunications Act of 1996 was the first significant overhaul in over 60 years amending the work of the Communications Act of 1934. Coming only two dozen years after the breakup of AT&T, the act sets out to move telecommunications into a state of competition with their markets and the networks they are a part of.[91] Up to this point the effects of the Telecommunications Act of 1996 have been seen, but some of the changes the Act set out to fix are still ongoing problems, such as being unable to create an open competitive market.
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The question of the 'first' publicly targeted licensed radio station in the U.S. has more than one answer and depends on semantics. Settlement of this 'first' question may hang largely upon what constitutes 'regular' programming
In many fields of communications equipment design, MOS LSI custom built circuits provide the only practical and economic solution. (...) A complete list of all applications is beyond the scope of this paper since new MOS developments are constantly being initiated in the various technical areas. Typical examples of completed and present MOS developments are:
— crosspoints
— multiplexers
— modems
— mobile radios
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