Чтение общенаучной литературы. Кытманова О.А. - 33 стр.

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speaking areas, most of the programs originate in Canada.
Technological Advances
You can read about how television and radio signals are sent and received in the
articles RADIO and TELEVISION. However, it is worth noting some important
developments in this brief section. In television, the greatest advance came with
the development of color transmissions. The television research pioneer John
Logie Baird provided the first successful practical demonstration of color
television in 1928, using mechanical scanning. Ten years later, the French inventor
Georges Valensi patented the first system that allowed color transmissions to be
received both by TV sets appropriate for the purpose and by sets only able to
receive programs in black and white. Some pioneering color broadcasts began
before World War II, but serious work on color broadcasting did not take place
until the 1950s The method of color transmission accepted by the National
Television Systems Committee (NTSC) was introduced in 1954 and has been
adopted in many countries as well as the United States. It is a "compatible" system
that can be received by both color sets receiving signals on the ultra high frequency
(UHF) channels and also by the black-and-white receivers taking very high
frequency (VHF) signals. Britain and Germany use a modified form of this NTSC
color system called PAL (phase alternation line). France and Russia use a more
complex system called SECAM (systeme electronique couleur avec memoire).
These systems are explained under TELEVISION. Regular color broadcasts began
in Britain on the BBC2 channel in 1967.
Satellite broadcasting became a reality on 10 July 1962, when the American
Telephone and Telegraph Company, using its artificial satellite "Telstar", beamed
television pictures in black and white from its transmitter in And-over, Maine, to
receiving stations at Goonhilly .
Downs, in the English county of Cornwall, and Pleumeur-Boudou, in Brittany,
France. The first color transmission followed on 16 July. These transmissions were
limited to short periods lasting only as long as the satellite was above the horizon
for both the transmitting and the receiving stations. Now broadcasts across the
world can be much longer because modern communications satellites are in what
scientists call "geostationary" or "geosynchronous" orbits. This means that they
always stay in the part of the sky relative to the transmitter and receiving station.
Transatlantic broadcasts between the United States and Europe are now a regular
occurrence. Space satellites now provide a world-wide television and telephone
network that links nearly every country on the globe.
During the 1980s the British government relaxed controls on broadcasting to
allow operations by cable companies similar to those of the United States. It also
opened the way for the spread of Direct Broadcasting by Satellite (DBS). This
system, already operating throughout Europe, uses satellites to beam programs of
high technical quality to television sets fitted with special large dish antennas to
collect the signal. DBS makes possible such advances as television with
stereophonic sound.

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