Telecommunications
Telecommunications is the communication of information
over a distance. Etymology: The term comes from
a contraction of the Greek tele, meaning 'far', and
communications, meaning "n : the discipline that studies the
principles of transmitting information and the methods by which it is
delivered (as print or radio or television etc.)" The
term is most commonly used to refer to communication using some type
of signaling, such as the aldis lamp or the transmission and reception
of electromagnetic energy. This covers many technologies including
radio, telegraphy, television, telephone, data communication and
computer networking, although other types of signaling are also
included. The basic elements of a simple
telecommunications system are: a.) a transmitter that
encodes the information to be communicated into some type of signal
b.) a signal that is transmitted by the transmitter b.)
a transmission medium, which constitutes a communications channel over
which the signal is transmitted c.) a receiver (such as
a radio receiver) that receives the signal and decodes the information
that was encoded upon it by the transmitter Note:
The transmission medium and the communications channel
may also be considered to exist separately - i.e., the communications
channel may be considered to consist of some limitation imposed
upon the transmission medium, either by the physical nature of the
transmission medium with respect to the type of signal energy that
will be used to transmit the information over it (for example
transmission lines, which have a finite bandwidth, create a 'channel'
for electromagnetic energy because of this frequency limitation), or
by some process designed explicitly for that purpose (such as
multiplexing). However, this distinction is not always made (since
virtually any practical transmission medium has some form of physical
limitation associated with it), and the transmission medium
'connecting' the transmitter to the receiver is itself considered to
be a communications channel (which, of course, may be further
subdivided into other 'channels' by multiplexing). The
transmitter is a device that transforms or encodes the message
into a physical phenomenon; the signal. The transmission
medium, by its physical nature, is likely to modify or degrade the
signal on its path from the transmitter to the receiver. The receiver
may therefore require a decoding mechanism to recover the message from
the received signal. This mechanism can be designed to tolerate a
significant degree of signal degradation. Sometimes, the final
"receiver" is the human eye, ear (or other sensory organ) and the
recovery of the message is done by the brain.
Telecommunication can be point-to-point, point-to-multipoint or
broadcasting, which is a particular form of point-to-multipoint that
goes only from the transmitter to the receivers. One of
the roles of the telecommunications engineer is to analyze the
physical properties of the line or transmission medium, and the
statistical properties of the message in order to design the most
effective encoding and decoding mechanisms. When
systems are designed to communicate through human sensory organs
(mainly those for vision and hearing), physiological and psychological
characteristics of human perception must be taken into account.
Certain types of defect, while objectively measurable, are not readily
apparent to human perception while others are disproportionately
apparent. The cost of a system can therefore be reduced by choosing to
omit certain information. There is clearly a tradeoff between reduced
cost and user demand for higher quality, and this is an important
economic consideration for those who plan systems. The
field of telecommunications is no doubt one of the most exciting
occupational fields that modern society has to offer. New technology
is constantly being developed and finds its applications in the
technical systems that make up a telecommunications network. This
creates opportunities for developing existing services further, and
introducing completely new ones.
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