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A cablegram was a message sent by a submarine telegraph cable, [4] often shortened to "cable" or "wire". The suffix -gram is derived from ancient Greek: γραμμα ( gramma ), meaning something written, i.e. telegram means something written at a distance and cablegram means something written via a cable, whereas telegraph implies the process ...
Wireless telegraphy or radiotelegraphy is the transmission of text messages by radio waves, analogous to electrical telegraphy using cables. [ 1 ] [ 2 ] Before about 1910, the term wireless telegraphy was also used for other experimental technologies for transmitting telegraph signals without wires.
Several generic digital data connection standards are designed to carry audio/video data along with other data and power: USB was designed as a single connector to support all needs, including any generic data, audio/video, power, and more; DisplayLink is its most successful Audio+Video protocol. Until the 3.0 revision, very low data rates ...
The receiver is then tuned so as to pick up the high-frequency wave and a demodulator is used to retrieve the signal containing the visual or audio information. The broadcast signal can be either analogue (signal is varied continuously with respect to the information) or digital (information is encoded as a set of discrete values). [41] [83]
Contemporary map of the 1858 transatlantic cable route. Transatlantic telegraph cables were undersea cables running under the Atlantic Ocean for telegraph communications. . Telegraphy is an obsolete form of communication, and the cables have long since been decommissioned, but telephone and data are still carried on other transatlantic telecommunication
Mathematical models of the channel can be made to describe how the input (the transmitted signal) is mapped to the output (the received signal). There exist many types and uses of channel models specific to the field of communication. In particular, separate models are formulated to describe each layer of a communication system.
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Telecommunications cable is a type of guided transmission medium. Telecommunications are based on transmitting and receiving modulated waves/signals through a medium. Types of telecommunications cable include: [1] [2] electrical cables when electric current is carried; transmission lines and waveguides when electromagnetic waves are transmitted; optical fibers when light signals are transmitted.