Communications

[|Telecommunication] - the assisted transmission of signals over a distance for the purpose of communication. Telecommunication typically involves the use of electronic transmitters such as the telephone, television, radio or computer.

[|Radio] - often refers to the actual transceiver device or chip. Transmission of signals by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space. Information is carried by systematically changing ( modulating) some property of the radiated waves, such as amplitude, frequency, phase, or pulse width.
 * The telegraph, 1837 - Before it, Joel Mokyr says, “information could move no faster than a man on horseback.”
 * The telephone, 1876 - Allowed our voices to travel
 * Radio, 1906 - The first demonstration of electronic mass media’s power to spread ideas and homogenize culture

[|wireless] - short-range computer networking, e.g., Wireless Local Area Network (WLAN), Wi-Fi, and Bluetooth, as well as mobile telephony, e.g., GSM and UMTS
 * [|Bluetooth] - an industrial specification for wireless personal area networks (PANs). Bluetooth provides a way to connect and exchange information between devices such as mobile phones, laptops, PCs, printers, digital cameras, and video game consoles over a secure, globally unlicensed short-range radio frequency. Bluetooth is designed for low power consumption, with a short range low-cost transceiver microchips in each device. Bluetooth enables these devices to communicate with each other when they are in range. The devices use a radio communications system, so they do not have to be in line of sight of each other, and can even be in other rooms, as long as the received transmission is powerful enough.

[|Microwaves] - An electromagnetic wave with a wavelength shorter than that of normal radio waves but longer than those of infrared radiation (heat) and of visible light.

[|Cellular] - make and receive telephone calls over a radio link while moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile phone operator, allowing access to the public telephone network. From 1990 to 2011, worldwide mobile phone subscriptions grew from 12.4 million to over 6 billion, penetrating about 87% of the global population

[|Optical fiber ( or optical fibre)] - a flexible, transparent fibre made of glass (silica) or plastic, slightly thicker than a human hair. It functions as a waveguide, or “ light pipe”, to transmit light between the two ends of the fibre. The field of applied science and engineering concerned with the design and application of optical fibers is known as fibre optics. Optical fibers are widely used in fibre-optic communications, which permits transmission over longer distances and at higher bandwidths (data rates) than other forms of communication.

Transmitter - source of electrical energy, producing alternating current of a desired frequency of oscillation. The transmitter contains a system to modulate (change) some property of the energy produced to impress a signal on it. This modulation might be as simple as turning the energy on and off, or altering more subtle properties such as amplitude, frequency, phase, or combinations of these properties.

Electromagnetic spectrum - Radio frequencies occupy the range from a few tens of hertz to three hundred gigahertz, although commercially important uses of radio use only a small part of this spectrum. Other types of electromagnetic radiation, with frequencies above the RF range, are microwave, infrared, visible light, ultraviolet, X-rays and gamma rays.

Receiver

Carrier

[|Telephone] - telephony - converts sound, typically and most efficiently the human voice, into electronic signals suitable for transmission via cables or other transmission media over long distances, and replays such signals simultaneously in audible form to its user. [|Television] - sends the picture as AM and the sound as AM or FM, with the sound carrier a fixed frequency (4.5 MHz in the NTSC system) away from the video carrier. Analog television also uses a vestigial sideband on the video carrier to reduce the bandwidth required.

Broadband

Networks

short-range wireless communications ( infrared, Bluetooth),


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 * antenna - device that transmits or receives radio or microwave signals.
 * [|microwaves] - An electromagnetic wave with a wavelength shorter than that of normal radio waves but longer than those of infrared radiation (heat) and of visible light.
 * radio - To send and receive radio waves; or the device that receives these transmissions.
 * satellite - A moon orbiting a planet or a vehicle or other manufactured object that orbits some celestial body in space.

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