Text №2 Radio

Do you have a favorite radio station? What do you like about it? Have you ever wondered how your radio is able to produce the sounds and the music that you like to hear? Radio programs are sent by a machine called a transmitter to your radio which is called a receiver. The programs don't travel through wires like telephone messages do. They are sent through the air over long distances by electromagnetic waves. These waves are called radio waves and were discovered by a German scientist named Heinrich Hertz. He discovered that these waves could carry sound signals. He also discovered that radio waves have different lengths. Guglielmo Marconi, an Italian, invented a microphone that changed sound waves into electronic signals, and then he developed a receiver that turned them back into sound again. He also found a way to keep waves of the same length together and keep those of different wave lengths separate. On his equipment, a radio wave looked like a letter "s" lying on its side. Short waves curved up and down more times each second than longer ones, so he divided all the waves by how many times they curved each second or by how frequently they curved. He called each group a frequency. The numbers on your radio dial are different frequencies. Different stations can broadcast their programs at the same time using different frequencies. Later, scientists found that by using only the top half of a radio wave they could reduce static and other noise that interfered with clear sound. This kind of radio transmission is called FM broadcasting because the frequency has been modulated or changed.

Text №3 Television is Developed

John Logie Baird (1888-1946) applied for a patent for a mechanical television in 1923. He ran successful experiments in transmitting images in 1926, and in 1930 he worked with the British Broadcasting Corporation (BBC) to begin mechanical television broadcasting. He also tried, rather unsuccessfully, to mass-market his television transmitter. In 1923 Vladimir Zworykin (1889-1982) also applied for a patent. He was for a television camera that converted optical images into electrical pulses. On November 18, 1929, at a convention of radio engineers, Zworykin demonstrated a television receiver containing his “kinescope”, a cathoderay tube. That same year Zworykin joined the Radio Corporation of America (RCA) in Camden, New Jersey. As the director of their Electronic Research Laboratory, he was able to concentrate on making critical improvements to his system. Zworykin’s “storage principle” is the basis of modern TV.

Meanwhile, in Japan, Kenjiro Takayanagi was developing electronic television, too. He was ahead of Zworykin, but better publicity gave Zworykin the nickname “father of television.” Takayanagi transmitted an image electronically in 1926, with a 40-line resolution and film running at 14 frames per second. In 1932 the BBC ventured the first regularly broadcast programs using Baird’s mechanical equipment, though it had been broadcasting special events and other sporadic transmissions since 1927. The first special-purpose television station was built in Germany in 1935 in preparation for the Berlin Olympic Games. That Olympic year, NBC experimented with electronic broadcast from the top of the Empire State Building. The first live journalistic event covered by television was the 1937 coronation of Britain’s King George VI. That year, the BBC began the first regular, high-quality broadcasting service using an electronic system.