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Radio and television were major agents of social change in the 20th century, opening windows to other peoples and places and bringing distant events directly into millions of homes. Although Guglielmo Marconi was the first to put the theory of radio waves into practice, the groundwork for his feat was laid in the 19th century by James Clerk Maxwell, Heinrich Hertz, and Nikola Tesla. Maxwell theorized and Hertz confirmed the feasibility of transmitting electromagnetic signals. Tesla invented a device—the Tesla coil-that converts relatively low-voltage current to high—voltage low current at high frequencies. Some form of the coil is still used in radio and television sets today.
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1900 |
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Tesla granted a U.S. patent
Nikola Tesla is granted a U.S. patent for a "system of transmitting electrical energy" and another patent for "an electrical transmitter"—both the products of his years of development in transmitting and receiving radio signals. These patents would be challenged and upheld (1903), reversed (1904), and finally restored (1943).
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1901 |
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Marconi picks up the first transatlantic radio signal
Guglielmo Marconi, waiting at a wireless receiver in St. John’s, Newfoundland, picks up the first transatlantic radio signal, transmitted some 2,000 miles from a Marconi station in Cornwall, England. To send the signal—the three dots of the Morse letter "s"—Marconi’s engineers send a copper wire aerial skyward by hoisting it with a kite. Marconi builds a booming business using radio as a new way to send Morse code.
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1904 |
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Fleming invents the vacuum diode
British engineer Sir John Ambrose Fleming invents the two-electrode radio rectifier; or vacuum diode, which he calls an oscillation valve. Based on Edison's lightbulbs, the valve reliably detects radio waves. Transcontinental telephone service becomes possible with Lee De Forest's 1907 patent of the triode, or three-element vacuum tube, which electronically amplifies signals.
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1906 |
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Audion
Expanding on Fleming’s invention, American entrepreneur Lee De Forest puts a third wire, or grid, into a vacuum tube, creating a sensitive receiver. He calls his invention the "Audion." In later experiments he feeds the Audion output back into its grid and finds that this regenerative circuit can transmit signals.
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1906 |
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Christmas Eve 1906 program
On Christmas Eve 1906 engineering professor Reginald Fessenden transmits a voice and music program in Massachusetts that is picked up as far away as Virginia.
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1912 |
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Radio signal amplifier devised
Columbia University electrical engineering student Edwin Howard Armstrong devises a regenerative circuit for the triode that amplifies radio signals. By pushing the current to the highest level of amplification, he also discovers the key to continuous-wave transmission, which becomes the basis for amplitude modulation (AM) radio. In a long patent suit with Lee De Forest, whose three-element Audion was the basis for Armstrong’s work, the courts eventually decide in favor of De Forest, but the scientific community credits Armstrong as the inventor of the regenerative circuit.
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1917 |
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Superheterodyne circuit
While serving in the U.S. Army Signal Corps during World War I, Edwin Howard Armstrong invents the superheterodyne circuit, an eight-tube receiver that dramatically improves the reception of radio signals by reducing static and increasing selectivity and amplification. He files for a patent the following year.
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1920 |
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First scheduled commercial radio programmer
Station KDKA in Pittsburgh becomes radio’s first scheduled commercial programmer with its broadcast of the Harding-Cox presidential election returns, transmitted at 100 watts from a wooden shack atop the Westinghouse Company’s East Pittsburgh plant. Throughout the broadcast KDKA intersperses the election returns and occasional music with a message: "Will anyone hearing this broadcast please communicate with us, as we are anxious to know how far the broadcast is reaching and how it is being received?"
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1925 |
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Televisor
Scottish inventor John Logie Baird successfully transmits the first recognizable image—the head of a ventriloquist’s dummy—at a London department store, using a device he calls a Televisor. A mechanical system based on the spinning disk scanner developed in the 1880s by German scientist Paul Nipkow, it requires synchronization of the transmitter and receiver disks. The Televisor images, composed of 30 lines flashing 10 times per second, are so hard to watch they give viewers a headache.
Charles F. Jenkins pioneers his mechanical wireless television system, radiovision, with a public transmission sent from a navy radio station across the Anacostia River to his office in downtown Washington, D.C. Jenkins’s radiovisor is a multitube radio set with a special scanning-drum attachment for receiving pictures—cloudy 40- to 48-line images projected on a six-inch-square mirror. Jenkins’s system, like Baird’s, broadcasts and receives sound and visual images separately. Three years later the Federal Radio Commission grants Charles Jenkins Laboratories the first license for an experimental television station.
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1927 |
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All-electronic television system
Using his all-electronic television system, 21-year-old Utah farm boy and electronic prodigy Philo T. Farnsworth transmits images of a piece of glass painted black, with a center line scratched into the paint. The glass is positioned between a blindingly bright carbon arc lamp and Farnsworth’s "image dissector" cathode-ray camera tube. As viewers in the next room watch a cathode-ray tube receiver, someone turns the glass slide 90 degrees—and the line moves. The use of cathode-ray tubes to transmit and receive pictures—a concept first promoted by British lighting engineer A. Campbell Swinton—is the death knell for the mechanical rotating-disk scanner system.
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1928 |
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Televisor system produces images in crude color
John Logie Baird demonstrates, with the aid of two ventriloquist’s dummies, that his Televisor system can produce images in crude color by covering three sets of holes in his mechanical scanning disks with gels of the three primary colors. The results, as reported in 1929 following an experimental BBC broadcast, appear "as a soft-tone photograph illuminated by a reddish-orange light."
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1929 |
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Television camera and a cathode-ray tube receiver
Vladimir Zworykin, who came to the United States from Russia in 1919, demonstrates the newest version of his iconoscope, a cathode-ray-based television camera that scans images electronically, and a cathode-ray tube receiver called the kinescope. The iconoscope, first developed in 1923, is similar to Philo Farnsworth’s "image dissector" camera tube invention, fueling the growing rivalry between the two inventors for the eventual title of "father of modern television."
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1933 |
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FM radio
Edwin Howard Armstrong develops frequency modulation, or FM, radio as a solution to the static interference problem that plagues AM radio transmission, especially in summer when electrical storms are prevalent. Rather than increasing the strength or amplitude of his radio waves, Armstrong changes only the frequency on which they are transmitted. However, it will be several years before FM receivers come on the market.
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1947 |
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Transistor is invented
The future of radio and television is forever changed when John Bardeen, Walter Brattain, and William Shockley of Bell Laboratories co-invent the transistor.
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1950s |
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Cathode-ray tube (CRT) for television monitors improved
Engineers improve the rectangular cathode-ray tube (CRT) for television monitors, eliminating the need for rectangular "masks" over the round picture tubes of earlier monitors. The average price of a television set drops from $500 to $200.
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1953 |
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RCA’s new system for commercial color adopted
RCA beats out rival CBS when the National Television System Committee adopts RCA’s new system for commercial color TV broadcasting. CBS has pioneered color telecasting, but its system is incompatible with existing black-and-white TV monitors throughout the country.
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1954 |
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First coast-to-coast color television transmission
The New Year’s Day Tournament of Roses in Pasadena, California, becomes the first coast-to-coast color television transmission, or "colorcast." The parade is broadcast by RCA’s NBC network to 21 specially equipped stations and is viewed on newly designed 12-inch RCA Victor receivers set up in selected public venues. Six weeks later NBC’s Camel News Caravan transmits in color, and the following summer the network launches its first color sitcom, The Marriage, starring Hume Cronyn and Jessica Tandy.
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1954 |
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First all-transistor radio
Regency Electronics introduces the TR-1, the first all-transistor radio. It operates on a 22-volt battery and works as soon as it is switched on, unlike tube radios, which take several minutes to warm up. The TR-1 sells for $49.95; is available in six colors, including mandarin red, cloud gray and olive green; and is no larger than a package of cigarettes.
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1958 |
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Integrated circuit
Jack S. Kilby of Texas Instruments and Robert Noyce of Fairchild Semiconductor, working independently, create the integrated circuit, a composite semiconductor block in which transistor, resistor, condenser, and other electrical components are manufactured together as one unit. Initially, the revolutionary invention is seen primarily as an advancement for radio and television, which together were then the nation’s largest electronics industry.
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1962 |
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Telstar 1
Communications satellite Telstar 1 is launched by a NASA Delta rocket on July 10, transmitting the first live transatlantic telecast as well as telephone and data signals. At a cost of $6 million provided by AT&T, Bell Telephone Laboratories designs and builds Telstar, a faceted sphere 34 inches in diameter and weighing 171 pounds. The first international television broadcasts shows images of the American flag flying over Andover, Maine to the sound of "The Star-Spangled Banner." Later that day AT&T chairman Fred Kappel makes the first long-distance telephone call via satellite to Vice President Lyndon Johnson. Telstar I remains in orbit for seven months, relaying live baseball games, images from the Seattle World's Fair, and a presidential news conference.
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1968 |
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200 million television sets
There are 200 million television sets in operation worldwide, up from 100 million in 1960. By 1979 the number reaches 300 million and by 1996 over a billion. In the United States the number grows from 1 million in 1948 to 78 million in 1968. In 1950 only 9 percent of American homes have a TV set; in 1962, 90 percent; and in 1978, 98 percent, with 78 percent owning a color TV.
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1988 |
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Sony "Watchman"
Sony introduces the first in its "Watchman" series of handheld, battery-operated, transistorized television sets. Model FD-210, with its 1.75-inch screen, is the latest entry in a 30-year competition among manufacturers to produce tiny micro-televisions. The first transistorized TV, Philco’s 1959 Safari, stood 15 inches high and weighed 15 pounds.
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1990 |
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FCC sets a testing schedule for proposed all-digital HDTV system
Following a demonstration by Philips two years earlier of a high-definition TV (HDTV) system for satellite transmission, the Federal Communications Commission sets a testing schedule for a proposed all-digital HDTV system. Tests begin the next year, and in 1996 Zenith introduces the first HDTV-compatible front-projection television. Also in 1996, broadcasters, TV manufacturers, and PC makers set inter-industry standards for digital HDTV. By the end of the century, digital HDTV, which produces better picture and sound than analog television and can transmit more data faster, is on the verge of offering completely interactive TV.
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