Information Technology Reference
In-Depth Information
City. Development of television was postponed until the end of World War II. By
that time, the economy had improved after the Great Depression, and families had
money to buy televisions. Although color television had been produced as early as
1928, the technology was not developed sufficiently until the U.S. government ap-
proved it in 1953.
Government regulation was required for television transmission because the
frequency spectrum is in the public domain, and frequencies must be controlled
so that only one transmitter uses a specific frequency, which government assigns.
Also, broadcasters are regulated so that they do not change their method of trans-
mission in ways that would render receivers useless.
Television signals originally were broadcast over the air by antennae placed on
tall buildings or mountains and then transmitted by cable to homes and offices in
the area—community antenna television (CATV). More recently, the signals have
been transmitted via satellite to community antennae and delivered via cable. In
recent years, television programs have been transmitted via the Internet to com-
puters and cell phones.
The Internet
Computers alone cannot transmit information; however, computers have en-
abled the establishment of the worldwide communication network we know as the
Internet. The U.S. Department of Defense initially sponsored computer science
research for a communication system that linked computers. The Advanced Re-
search Projects Agency (ARPS) conducted the research that developed a network
of computers called ARPANET in 1969. The network linked computers via tele-
phone lines at research facilities in the United States and enabled the transfer of
files among computers—communication that became known as e-mail.
ARPANET was expanded beyond government agencies to private companies,
and in 1983 an international set of standards (Internet) was implemented, and that
term became used to describe the worldwide network. Key components are the In-
ternet service providers (ISPs), which provide individuals access to any other com-
puter on the network. While some people may call the Internet “the global informa-
tion infrastructure,” we submit that it is only one component (albeit a very important
one) in the information infrastructure.
Communication Satellites
A relatively recent addition to the global information infrastructure is the com-
munication satellite. First proposed in a scientific paper written in 1945, the earliest
satellite was launched by the U.S. Air Force in 1958. To be effective, a satellite
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