A communications system is a collection of individual telecommunications networks systems, relay stations, tributary stations, and terminal equipment usually capable of

interconnection In telecommunications, interconnection is the physical linking of a carrier's network with equipment or facilities not belonging to that network. The term may refer to a connection between a carrier's facilities and the equipment belonging to its ...

and interoperation to form an integrated whole. Communication systems allow the transfer of information from one place to another or from one device to another through a specified channel or medium. The components of a communications system serve a common purpose, are technically compatible, use common procedures, respond to controls, and operate in union. In the structure of a communication system, the transmitter first converts the data received from the source into a light signal and transmits it through the medium to the destination of the receiver. The receiver connected at the receiving end converts it to digital data, maintaining certain protocols e.g. FTP, ISP assigned protocols etc.

Telecommunications Telecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information over a distance using electronic means, typically through cables, radio waves, or other communication technologies. These means of ...

is a method of

communication Communication is commonly defined as the transmission of information. Its precise definition is disputed and there are disagreements about whether Intention, unintentional or failed transmissions are included and whether communication not onl ...

(e.g., for sports

broadcasting Broadcasting is the data distribution, distribution of sound, audio audiovisual content to dispersed audiences via a electronic medium (communication), mass communications medium, typically one using the electromagnetic spectrum (radio waves), ...

mass media Mass media include the diverse arrays of media that reach a large audience via mass communication. Broadcast media transmit information electronically via media such as films, radio, recorded music, or television. Digital media comprises b ...

journalism Journalism is the production and distribution of reports on the interaction of events, facts, ideas, and people that are the "news of the day" and that informs society to at least some degree of accuracy. The word, a noun, applies to the journ ...

, etc.). Communication is the act of conveying intended meanings from one entity or group to another through the use of mutually understood signs and

semiotic Semiotics ( ) is the systematic study of semiosis, sign processes and the communication of Meaning (semiotics), meaning. In semiotics, a Sign (semiotics), sign is defined as anything that communicates intentional and unintentional meaning or feel ...

rules.

Types

By media

optical communication Optical communication, also known as optical telecommunication, is communication at a distance using light to carry information. It can be performed visually or by using electronic devices. The earliest basic forms of optical communication date ...

system is any form of communications system that uses

light Light, visible light, or visible radiation is electromagnetic radiation that can be visual perception, perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400– ...

as the transmission medium. Equipment consists of a

transmitter In electronics and telecommunications, a radio transmitter or just transmitter (often abbreviated as XMTR or TX in technical documents) is an electronic device which produces radio waves with an antenna (radio), antenna with the purpose of sig ...

, which encodes a ''

message A message is a unit of communication that conveys information from a sender to a receiver. It can be transmitted through various forms, such as spoken or written words, signals, or electronic data, and can range from simple instructions to co ...

'' into an optical ''

signal A signal is both the process and the result of transmission of data over some media accomplished by embedding some variation. Signals are important in multiple subject fields including signal processing, information theory and biology. In ...

'', a ''

communication channel A communication channel refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel in telecommunications and computer networking. A channel is used for infor ...

'', which carries the signal to its destination, and a receiver, which reproduces the message from the received optical signal.

Fiber-optic communication Fiber-optic communication is a form of optical communication for transmitting information from one place to another by sending pulses of infrared or visible light through an optical fiber. The light is a form of carrier wave that is modul ...

systems transmit information from one place to another by sending light through an

optical fiber An optical fiber, or optical fibre, is a flexible glass or plastic fiber that can transmit light from one end to the other. Such fibers find wide usage in fiber-optic communications, where they permit transmission over longer distances and at ...

. The light forms a

carrier signal In telecommunications, a carrier wave, carrier signal, or just carrier, is a periodic waveform (usually sinusoidal) that conveys information through a process called ''modulation''. One or more of the wave's properties, such as amplitude or frequ ...

that is modulated to carry information. A radio communication system is composed of several communications

subsystem A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundaries, structure and purpose and is exp ...

s that give exterior communications capabilities. A radio communication system comprises a transmitting conductor in which electrical

oscillation Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum ...

s or

currents Currents, Current or The Current may refer to: Science and technology * Current (fluid), the flow of a liquid or a gas ** Air current, a flow of air ** Ocean current, a current in the ocean *** Rip current, a kind of water current ** Current (hy ...

are produced and which is arranged to cause such currents or oscillations to be propagated through the

free space A vacuum (: vacuums or vacua) is space devoid of matter. The word is derived from the Latin adjective (neuter ) meaning "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressur ...

medium from one point to another remote therefrom and a receiving conductorJohn Stone Stone, at such distant point adapted to be excited by the oscillations or currents propagated from the transmitter.John Stone Stone,

Power-line communication Power-line communication (PLC) is the carrying of data on a conductor (the ''power-line carrier'') that is also used simultaneously for AC electric power transmission or electric power distribution to consumers. A wide range of power-line comm ...

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 In an electric circuit, instantaneous power is the time rate of flow of energy past a given point of the circuit. In alternating current circuits, energy storage elements such as inductors and capacitors may result in periodic reversals of the d ...

, 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 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 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 In physics, electromagnetic radiation (EMR) is a self-propagating wave of the electromagnetic field that carries momentum and radiant energy through space. It encompasses a broad spectrum, classified by frequency or its inverse, wavelength, ran ...

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 Communications System (DCS).

Examples: by technology

Telephone A telephone, colloquially referred to as a phone, is a telecommunications device that enables two or more users to conduct a conversation when they are too far apart to be easily heard directly. A telephone converts sound, typically and most ...

Mobile phone A mobile phone or cell phone is a portable telephone that allows users to make and receive calls over a radio frequency link while moving within a designated telephone service area, unlike fixed-location phones ( landline phones). This rad ...

Tablet computer A tablet computer, commonly shortened to tablet, is a mobile device, typically with a mobile operating system and touchscreen display processing circuitry, and a rechargeable battery in a single, thin and flat package. Tablets, being computers ...

Television Television (TV) is a telecommunication medium for transmitting moving images and sound. Additionally, the term can refer to a physical television set rather than the medium of transmission. Television is a mass medium for advertising, ...

Telegraph Telegraphy is the long-distance transmission of messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message. Thus flag semaphore is a method of telegraphy, whereas ...

*Edison Telegraph * TV cable *

Computer A computer is a machine that can be Computer programming, programmed to automatically Execution (computing), carry out sequences of arithmetic or logical operations (''computation''). Modern digital electronic computers can perform generic set ...

By application area

The term

transmission system In telecommunications, a transmission system is a communication system that transmits a signal from one place to another. The signal can be an signal (electrical engineering), electrical, fiber-optic communication, optical or radio wave, radio s ...

is used in the telecommunications industry to emphasize the intermediate

media Media may refer to: Communication * Means of communication, tools and channels used to deliver information or data ** Advertising media, various media, content, buying and placement for advertising ** Interactive media, media that is inter ...

protocols Protocol may refer to: Sociology and politics * Protocol (politics), a formal agreement between nation states * Protocol (diplomacy), the etiquette of diplomacy and affairs of state * Etiquette, a code of personal behavior Science and technology ...

, and

equipment Equipment most commonly refers to a set of tool A tool is an Physical object, object that can extend an individual's ability to modify features of the surrounding environment or help them accomplish a particular task. Although many Tool use by ...

in the 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 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 Data ( , ) are a collection of discrete or continuous values that convey information, describing the quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted for ...

, and

video Video is an Electronics, electronic medium for the recording, copying, playback, broadcasting, and display of moving picture, moving image, visual Media (communication), media. Video was first developed for mechanical television systems, whi ...

, 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. An

Emergency communication system An emergency communication system (ECS) is any system (typically computer-based) that is organized for the primary purpose of supporting one-way and two-way communication of emergency information between both individuals and groups of individuals ...

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 An automated call distribution system, commonly known as automatic call distributor or automatic call dispatcher (ACD), is a telephony device that answers and distributes incoming calls to a specific group of terminals or agents within an organiz ...

(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 Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through a given section of controlled airspace, and can provide advisory services to aircraft in non-controlled air ...

). 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 A dial tone (dialling tone in the UK) is a telephony signal sent by a telephone exchange or private branch exchange (PBX) to a terminating device, such as a telephone, when an off-hook condition is detected. It indicates that the exchange is ...

, or lengthy recorded announcements, radio and telephone lines equally easily connected to, individual lines immediately accessible etc..)

Key components

Sources

Sources can be classified as electric or non-electric; they are the origins of a message or input signal. Examples of sources include but are not limited to the following: * Audio files (MP3, WAV, etc...) * Graphic Image Files (GIFs) * Email Messages *

Human voice The human voice consists of sound Voice production, made by a human being using the vocal tract, including Speech, talking, singing, Laughter, laughing, crying, screaming, shouting, humming or yelling. The human voice frequency is specifically ...

* Television Picture *

Electromagnetic radiation In physics, electromagnetic radiation (EMR) is a self-propagating wave of the electromagnetic field that carries momentum and radiant energy through space. It encompasses a broad spectrum, classified by frequency or its inverse, wavelength ...

Input transducers (sensors)

Sensors, like microphones and cameras, capture non-electric sources, like sound and light (respectively), and convert them into electrical signals. These types of sensors are called input transducers in modern analog and digital communication systems. Without input transducers there would not be an effective way to transport non-electric sources or signals over great distances, i.e. humans would have to rely solely on our eyes and ears to see and hear things despite the distances. Other examples of input transducers include: *

Microphone A microphone, colloquially called a mic (), or mike, is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and publi ...

s *

Camera A camera is an instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photograp ...

s * Keyboards *

Mouse A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus'' ...

* Force sensors *

Accelerometer An accelerometer is a device that measures the proper acceleration of an object. Proper acceleration is the acceleration (the rate of change (mathematics), rate of change of velocity) of the object relative to an observer who is in free fall (tha ...

Transmitter

Once the source signal has been converted into an electric signal, the transmitter will modify this signal for efficient transmission. In order to do this, the signal must pass through an electronic circuit containing the following components: # Noise filter #

Analog-to-digital converter In electronics, an analog-to-digital converter (ADC, A/D, or A-to-D) is a system that converts an analog signal, such as a sound picked up by a microphone or light entering a digital camera, into a Digital signal (signal processing), digi ...

# Encoder # Modulator # Signal amplifier After the signal has been amplified, it is ready for transmission. At the end of the circuit is an antenna, the point at which the signal is released as electromagnetic waves (or electromagnetic radiation).

Communication channel

A communication channel is simply referring to the medium by which a signal travels. There are two types of media by which electrical signals travel, i.e. guided and unguided. Guided media refers to any medium that can be directed from transmitter to receiver by means of connecting cables. In optical fiber communication, the medium is an optical (glass-like) fiber. Other guided media might include coaxial cables, telephone wire, twisted-pairs, etc... The other type of media, unguided media, refers to any communication channel that creates space between the transmitter and receiver. For radio or RF communication, the medium is air. Air is the only thing between the transmitter and receiver for RF communication while in other cases, like sonar, the medium is usually water because sound waves travel efficiently through certain liquid media. Both types of media are considered unguided because there are no connecting cables between the transmitter and receiver. Communication channels include almost everything from the vacuum of space to solid pieces of metal; however, some mediums are preferred more than others. That is because differing sources travel through subjective mediums with fluctuating efficiencies.

Receiver

Once the signal has passed through the communication channel, it must be effectively captured by a receiver. The goal of the receiver is to capture and reconstruct the signal before it passed through the transmitter (i.e. the A/D converter, modulator and encoder). This is done by passing the "received" signal through another circuit containing the following components: # Noise Filter #

Digital-to-analog converter In electronics, a digital-to-analog converter (DAC, D/A, D2A, or D-to-A) is a system that converts a digital signal into an analog signal. An analog-to-digital converter (ADC) performs the reverse function. DACs are commonly used in musi ...

# Decoder # Demodulator # Signal Amplifier Most likely the signal will have lost some of its energy after having passed through the communication channel or medium. The signal can be boosted by passing it through a signal amplifier. When the analog signal converted into digital signal.

Output transducer

The output transducer simply converts the electric signal (created by the input transducer) back into its original form. Examples of output transducers include but are not limited to the following: * Speakers (Audio) * Monitors (See Computer Peripherals) * Motors (Movement) * Lighting (Visual)

Other

Some common pairs of input and output transducers include: # Microphones and speakers (audio signals) # Keyboards and computer monitors # Cameras and liquid crystal displays (LCDs) # Force sensors (buttons) and lights or motors Again, input transducers convert non-electric signals like voice into electric signals that can be transmitted over great distances very quickly. Output transducers convert the electric signal back into sound or picture, etc... There are many different types of transducers and the combinations are limitless.