Page 39 - Encyclopedia Of World History Vol V

1816 berkshire encyclopedia of world history

Long-distance calls, both on land and across oceans, were transmit not only dots and dashes, but also voice and
suddenly as cheap as local calls. From 1960 to 1990, for music.The most important of these was the triode, or vac-
example, the cost of a call from New York to London fell uum tube, patented by the American Lee De Forest
from thirty U.S. dollars to ten cents a minute. (1873–1961) in 1907. Starting in 1913, it was used in
Even as telephony was changing global communica- long-distance telephony, then in radio equipment during
tions, another series of technological innovations was World War I.
transforming telephones at the local level.With the com- Until the mid-1920s, long-distance radio telegraphy
puterization of the network, telephones could perform used long waves that required enormous energy-hungry
new functions that had not been possible before. Push- transmitters.Then Marconi and other researchers found
button dialing, call waiting, caller identification, and that short waves (200 meters or less, or frequencies of
voice mail were among the innovations. It also became more than 1500 kilohertz—more than 1.5 million wave
possible to use telephones as data communication cycles per second) could be produced by inexpensive
machines: One could key in numbers to access bank small transmitters, yet be heard around the world.While
accounts or communicate with programmed answering the cables and big long-wave transmitters almost shut
machines.The telephone network was also used to carry down, short-wave communication now came within
data between computers, via modems. As with all inno- reach of any ship, island, or remote mining camp. In
vations in electronics, in the advanced industrial countries World War II, short-wave radios were used by both sides
the initial cost of the new telephony was high but fell rap- to communicate with airplanes, warships and sub-
idly; for their inhabitants, the world soon formed one marines, tanks, and even spies.
giant and easily accessible network. Most of the world, Microwave radio (with wavelengths measured in centi-
however, was left far behind.Today, for example, there are meters and frequencies of more than 1,000 megahertz—
more telephone lines in Manhattan than in all of Africa, more than a billion cycles per second) found application
and most of the people of India and China have never not only in radar, but also, from the 1950s, as an alter-
used a telephone. native to copper cables in telephone networks. As men-
tioned above, microwave radio transmissions, like
Radio Telegraphy fiber-optic cables, dramatically reduced the cost of tele-
and Telephony phone calls.
The technology of radio began very differently from that In the 1990s the combination of computers and
of wired telegraphy and telephony, but wireless and microwaves revolutionized the telephone industry yet
wired technologies soon interacted with each other and again. The invention of cell (or mobile) phones made it
are now almost indistinguishable. Though there had possible for people to talk to one another or to send brief
been scientific experiments before, it was a young Irish- text messages while walking or driving.As the cost of cell
Italian, Guglielmo Marconi (1874–1937), who in 1895 phone service came down to a level comparable to that
was the first to use electromagnetic waves as a means of of wired telephone service, cell phones became among
communication. By 1898 he was able to send messages the most popular consumer items in Europe, North
in code over 40 kilometers, and in 1901 he transmitted America, and Japan.
the letter “S” across the Atlantic. He quickly established
a company to communicate with ships at sea and to com- The Future of
pete with the cable companies in transcontinental Telecommunications
communications. Technological revolutions in telecommunications, espe-
For the first decade, transmitters used sparks to create cially from the mid 1980s onward, have caused turmoil
radio waves, but soon others invented devices that could in the industry. Former monopolies such as AT&T in the