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The Invention of Television Technology

It is hard for Americans in the twenty-first century to envision a worldwithout television. According to U.S. Census Bureau statistics from

2004, 98 percent of households in the United States contain at leastone TV set, and the average household has 2.4 sets. TV sets in the2000s often have large screens (at least 32 inches across) that showhigh-definition color images. Cable and satellite systems, which are avail-able to about 80 percent of U.S. homes, give viewers hundreds of pro-grams from which to choose. Typical Americans spend more thanfour hours each day watching television. They depend on TV for enter-tainment as well as news and information, and they expect to see instan-taneous, live coverage of various types of events from around the world.

Yet television is a relatively new invention. The technology thatallowed people to send moving images across great distances did not be-come available until the 1920s, and most commercial development of TVtook place after 1945. In fact, the grandparents of young people inschool in 2006 can probably remember the first time they ever saw aTV set. That set almost certainly had a tiny screen (between 4 and10 inches across) that showed grainy, black-and-white images. In theearly days of TV, there were only three television networks. These net-works broadcast programs only a few days each week, for an hour ortwo in the evening. For many years, television viewing was such a specialevent that people who owned TV sets often invited friends and neigh-bors over to watch the shows. Over the course of just a few decades,however, television has become a constant presence in people’s livesand one of the most influential forces in American culture.

Dreaming of distance visionTelevision did not arise out of the work of a single inventor. Instead, anumber of inventors, scientists, and engineers made important contribu-tions to the development of TV technology. Perhaps the first invention

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that contributed to the later development of TVwas the telegraph. Introduced by Samuel Morse(1791–1872) in 1835, the telegraph allowed peopleto exchange coded messages by transmitting(sending) a series of tapping sounds over electricalwires. Although the telegraph did not allow forthe transmission of voices or pictures, its inven-tion opened the door to long-distance communi-cation. The next step in the development ofcommunication technology was the 1876 inven-tion of the telephone by Alexander Graham Bell(1847–1922). Unlike the telegraph, which limitedcommunication to codes made up of dots anddashes, the telephone enabled people to sendlive voice messages across many miles of wires.

Almost as soon as the telephone was intro-duced, scientists began dreaming about the pos-sibility of transmitting visual images of people,objects, and events. They referred to this excitingpotential technology as distance vision or seeingat a distance. Bell himself spent time working todevelop a picture phone that would enable peo-ple to see each other as they talked on the tele-phone. The idea of viewing live, movingpictures across a distance also captured the pub-lic’s imagination during the late nineteenth cen-tury. Scientific American magazine, for instance,ran its first articles about the potential for dis-tance vision in 1880. Futuristic cartoons of theperiod showed people sitting at home watchingsports and current events projected on a wallor a small screen. The topic of distance visiongenerated so much public interest that it was fea-tured at the 1900 World’s Fair (major events heldin large cities around the world that gave peoplean opportunity to see and experience new tech-nologies) in Paris, France, where Russian scientistConstantin Perskyi became the first person touse the word television.

Origins of TelevisionTerminology

The word ‘‘television,’’ which means ‘‘seeing ata distance,’’ was first used to describe the fu-turistic technology at the 1900 World’s Fair byRussian scientist Constantin Perskyi. It com-bined two root words of different origins: theGreek word ‘‘tele,’’ meaning ‘‘distant,’’ and theLatin word ‘‘visio,’’ meaning ‘‘sight.’’ Oncetelevision technology became a reality in thelate 1920s, some critics did not like the term.The editor of the British newspaper Manches-ter Guardian, for instance, once famouslywrote: ‘‘Television? The word is half Greek andhalf Latin. No good will come of it.’’

More complaints were heard in England in1936, during a competition to decide whattelevision system would be adopted as stan-dard by the British Broadcasting Corporation(BBC). Some people claimed that, given theroots of the word, the verb ‘‘televise’’ shouldactually refer to the act of watching a programrather than the act of broadcasting one. Peoplesuggested a wide variety of alternative namesthat they felt better described TV technology,including radioscope, farscope, mirascope,optiphone, and lustreer.

The early days of television also saw manyarguments over what to call television viewers.During the 1936 competition, for example,London newspapers generally referred topeople watching the test broadcasts as‘‘lookers’’ or ‘‘lookers-in.’’ Some people feltthat this term was too narrow, since people notonly watched but also listened to TV. A num-ber of alternative terms were suggested—suchas perceptors, audiobservers, telegazers, tele-seers, inviders, and audivists—but the simplerterm ‘‘viewers’’ eventually caught on.

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Another important step in the development of long-distance com-munications technology came in 1887, when Heinrich Rudolf Hertz(1857–1894) discovered radio waves. Radio waves are electromagneticenergy that travels through the air (see sidebar ‘‘Broadcasting overRadio Waves’’). In 1895 a scientist named Guglielmo Marconi (1874–1937) used Hertz’s discovery to develop a wireless telegraph. Alsoknown as a radio telegraph, this invention allowed telegraph messagesto be sent through the air on radio waves instead of through wires.Marconi first demonstrated his invention in 1899 by sending a messageacross the English Channel (a twenty-mile-wide body of water separatingGreat Britain and France). The wireless telegraph soon led to the devel-opment of broadcast radio, which allowed voices, music, and othersounds to be transmitted wirelessly through the air. Lee DeForest(1873–1961) demonstrated this new technology in 1908 by broadcastingfrom the top of the Eiffel Tower in Paris, France. Some 500 miles awaylisteners with radio receivers were able to hear DeForest’s broadcast. Itwas only a matter of time before inventors figured out how to use similartechnology to broadcast pictures.

Experimenting with lightWhile all of these inventions were paving the way for television, a numberof scientists and engineers were actively trying to develop the technologyto transmit moving images. The earliest efforts involved the chemical el-ement selenium. In 1873 scientists discovered that selenium responded tovariations in the intensity of light. In other words, the element’s ability toconduct electricity changed depending on whether it was exposedto bright light or dim light. For several years, inventors tried to useselenium’s light sensitivity to convert moving images into electricalimpulses, but they eventually found that the element responded tooslowly for this purpose.

In 1884 German scientist Paul G. Nipkow (1860–1940) applied for apatent (a form of legal protection that gives an inventor exclusive rights touse and market an invention for a certain number of years) on an inventionhe called an electric telescope. Nipkow’s invention successfully scanned thelight reflected by a moving image, turned it into an electrical signal, andtransmitted it across a wire. His system used a set of spinning metaldisks with holes arranged in a spiral pattern to scan the image. Insideeach hole were photosensitive cells (cells sensitive to light) that, as thedisks spun, repeatedly measured the amount of light hitting the hole.

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The cells then sent electrical signals that varied in strength depending onthe amount of light hitting them. These signals were transmitted acrossa wire to a similar device at the other end, which reversed the processand turned the electrical signals back into light. The light source variedin intensity depending on the strength of the electrical signals it receivedand thus created a crude representation of the moving image at theother end of the wire. Nipkow’s system of spinning disks provided the

Broadcasting over Radio Waves

Television broadcasting, along with all othertypes of wireless communication, relies uponradio waves. Radio waves are made up of elec-trical and magnetic energy that travels throughspace. These electromagnetic waves have twomain characteristics: amplitude, which is a mea-sure of the strength or height of each wave; andfrequency, which is a measure of how quickly thewave repeats itself, or occurs at any given point.

Both of these characteristics of radio waves vary.Waves that are stronger, or taller, have a higheramplitude. Waves that occur more rapidly havea higher frequency. The frequency of radiowaves is measured in hertz (named after theGerman physicist Heinrich Rudolf Hertz [1857–1894], who discovered radio waves in 1887).Using metric prefixes, the term kilohertz or KHzmeans one thousand hertz, while megahertz orMHz means one million hertz.

Not all electromagnetic energy takes the form ofradio waves. At higher frequencies, the wavesbecome infrared light. At even higher frequen-cies, they appear as visible light. At other, in-creasingly high frequencies, they turn intoultraviolet light and X rays. Some people aresurprised to learn that the type of energy in radiowaves is actually related to light rather than tosound. Radio waves occur in a continuousspectrum, like the colors of the rainbow in thespectrum of visible light. Each part of the radio

spectrum provides a different frequency, orbroadcast channel.

Radio waves can be used to carry many types ofcommunication signals, including music, televi-sion programs, cellular phone calls, and wirelessInternet data. In order to transmit such infor-mation from one place to another, it must beattached to the radio waves through a processcalled modulation. Modulating a radio waveinvolves changing one or both of its basic char-acteristics. Changing the strength of the wave iscalled amplitude modulation, which is commonlyabbreviated AM. Changing the repetition pat-tern of the wave is called frequency modulation,abbreviated FM. There are many other types ofmodulation, but they are all variations or com-binations of AM and FM. For example, one ofthe types that is often used to carry televisionbroadcast signals, Vestigial Sideband (VSB), is aform of AM.

Although the spectrum of useful radio waves islarge, it is not unlimited. If two radio or televisionstations in the same area broadcast on the samefrequency, their signals may interfere with eachother, causing poor reception. In order to pre-vent interference between different types ofcommunication signals, the Federal Communi-cations Commission (FCC) divides up the radiospectrum and assigns frequencies to broadcast-ers through a system of licenses.

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foundation for mechanical television sets. Mechanical TV sets were per-fected in 1926 by two independent inventors, American Charles FrancisJenkins (1867–1934) and Scotsman John Logie Baird (1888–1946).

Other scientists followed a different path to develop electronic tele-vision sets. Electronic TV systems were based on cathode rays—the lightrays that were emitted when an electrical current was forced through avacuum tube. This technology served as the foundation for modern

Scottish inventor John L. Bairdsits in front of his invention,the ‘‘televisor,’’ an earlytelevision, 1927.� BETTMANN/CORBIS.

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