Editing Communications system (section)

== Types ==
=== By media===
An [[optical communication]] system is any form of communications system that uses [[light]] as the transmission medium. Equipment consists of a [[transmitter]], which encodes a ''[[message]]'' into an optical ''[[signal]]'', a ''[[communication channel]]'', which carries the signal to its destination, and a [[Radio receiver|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 a [[carrier signal]] that is [[Modulation|modulated]] to carry information.

A [[radio communication system]] is composed of several communications [[subsystem]]s that give exterior communications capabilities.<ref>Schwartz, M., Bennett, W. R., & Stein, S. (1996). ''Communication systems and techniques''. New York: IEEE Press.</ref>{{page needed|date=May 2023}}<ref>Rappaport, T. S. (1996). ''Wireless communications: principles and practice''. Upper Saddle River, N.J.: Prentice Hall PTR.</ref>{{page needed|date=May 2023}}<ref name=":0">{{cite web |url=http://www.fas.org/man/dod-101/sys/ship/weaps/radio.htm |title=Radio Communications System |access-date=2021-02-09}}</ref> A radio communication system comprises a transmitting [[Electrical conductor|conductor]]<ref name="JSS717512" /> in which electrical  [[oscillation]]s<ref>[[John Stone Stone]], {{US patent|726476}}</ref><ref>John Stone Stone, {{US patent|726368}}</ref><ref>John Stone Stone, {{US patent|577214}}</ref> or [[Electric current|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<ref name="JSS717512">John Stone Stone, {{US patent|717512}}</ref> at such distant point adapted to be excited by the oscillations or currents propagated from the transmitter.<ref>[[Nikola Tesla]], {{US patent|649621}}</ref><ref>Nikola Tesla, {{US patent|787412}}</ref><ref>John Stone Stone, {{US patent|714756}}</ref><ref>John Stone Stone, {{US patent|716955}}</ref>

[[Power-line communication]] systems operate by impressing a modulated carrier signal on power wires. Different types of power-line 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.

===By technology===
A [[Duplex (telecommunications)|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 used when describing communication between 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. An [[Antenna (radio)|antenna]] is basically a small length of a conductor that is used to radiate or receive electromagnetic waves. It acts as a conversion device. At the transmitting end it converts high frequency current into electromagnetic waves. At the receiving end it transforms [[electromagnetic waves]] into electrical signals that is fed into the input of the receiver. several types of antenna are used in communication.

Examples of communications subsystems include the [[Defense Information Systems Agency|Defense Communications System]] (DCS).

===Examples: by technology===
*[[Telephone]]
*[[Mobile phone]]
*[[Tablet computer]]
*[[Television]]
*[[Telegraphy|Telegraph]]
*Edison Telegraph
*[[TV cable]]
*[[Computer]]

===By application area===
The term [[transmission system]] is used in the telecommunications industry to emphasize the intermediate [[transmission media|media]], [[communication protocol|protocols]], and [[telecommunications equipment|equipment]] in the [[telecommunication circuit|circuit]], rather than particular end-user applications.

A [[tactical communications system]] is a communications system that 
(a) is used within, or in direct support of [[military tactics|tactical force]]s
(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 (Military)|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.

An [[Emergency communication system]] is any system (typically computer based) that is organized for the primary purpose of supporting the two way communication of emergency messages between both individuals and groups of individuals. These systems are commonly designed to integrate the cross-communication of messages between are variety of communication technologies.

An [[Automatic call distributor]] (ACD) is a communication system that automatically queues, assigns and connects callers to handlers. This is used often in customer service (such as for product or service complaints), ordering by telephone (such as in a ticket office), or coordination services (such as in [[air traffic control]]).

A [[Voice Communication Control System]] (VCCS) is essentially an ACD with characteristics that make it more adapted to use in critical situations (no waiting for [[dial tone]], or lengthy recorded announcements, radio and telephone lines equally easily connected to, individual lines immediately accessible etc..)