| |
|
In
telecommunication, a communications system is a
collection of individual communications networks, transmission
systems, relay stations, tributary stations, and data terminal
equipment (DTE)
usually capable of interconnection and interoperation to form an
integrated whole. The components of a communications system
serve a common purpose, are technically compatible, use common
procedures, respond to controls, and operate in unison.
Telecommunications is a method of communication (e.g., for
sports broadcasting, mass media, journalism, etc.).
A communications subsystem
is a functional unit or operational assembly that is smaller
than the larger assembly under consideration. Examples of
communications subsystems in the Defense Communications System (DCS)
are (a) a satellite link with one Earth terminal in
CONUS and one in Europe, (b)
the interconnect facilities at each Earth terminal of the
satellite link, and (c) an optical fiber cable with its driver
and receiver in either of the interconnect facilities.
Communication subsystem (b) basically consists of a receiver,
frequency translator and a transmitter. It also contains
transponders and other transponders in it and communication
satellite communication system receives signals from the antenna
subsystem.
An
optical communication system is any form of telecommunication
that uses light as the transmission medium. Optical
communications consists of a transmitter, which encodes a
message into an optical signal, a channel,
which carries the signal to its destination, and a receiver,
which reproduces the message from the received optical signal.
Fiber-optic communication systems transmit information from one
place to another by sending light through an optical fiber. The
light forms an electromagnetic carrier wave that is modulated to
carry information. First developed in the 1970s, fiber-optic
communication systems have revolutionized the telecommunications
industry and played a major role in the advent of the
Information Age. Because of its advantages over electrical
transmission, the use of optical fiber has largely replaced
copper wire communications in core networks in the developed
world.
A radio communication system is
composed of several communications subsystems that give exterior
communications capabilities. A radio communication system
comprises a transmitting conductor in which electrical
oscillations or currents are produced and which is arranged to
cause such currents or oscillations to be propagated through the
free space medium from one point to another remote therefrom and
a receiving conductor at such distant point adapted to be
excited by the oscillations or currents propagated from the
transmitter.
Power line communications
systems operate by impressing a modulated carrier signal on
the wiring system. Different types of powerline communications
use different frequency bands, depending on the signal
transmission characteristics of the power wiring used. Since the
power wiring system was originally intended for transmission of
AC power, the power wire circuits have only a limited ability to
carry higher frequencies. The propagation problem is a limiting
factor for each type of power line communications.
A duplex communication
system is a system composed of two connected parties or
devices which can communicate with one another in both
directions. The term duplex is not used when describing
communication between more than two parties or devices. Duplex
systems are employed in nearly all communications networks,
either to allow for a communication "two-way street" between two
connected parties or to provide a "reverse path" for the
monitoring and remote adjustment of equipment in the field.
A tactical communications
system is a communications system that (a) is used within,
or in direct support of, tactical forces, (b) is designed to
meet the requirements of changing tactical situations and
varying environmental conditions, (c) provides securable
communications, such as voice, data, and video, among mobile
users to facilitate command and control within, and in support
of, tactical forces, and (d) usually requires extremely short
installation times, usually on the order of hours, in order to
meet the requirements of frequent relocation.
Other Communication /
Telecommunication Categories:
|
|
