Data sending is essentially the same thing as digital communications, and implies physical sending of a message as a digital bit stream, represented as an electro-magnetic signal, over a physical point-to-point or point-to-multipoint communication channel. Examples of such channels are copper wires, optical fibers, wireless communication channels, and storage media. Data sending is a subset of the field of data communications, which also includes computer networking or computer communication applications and networking protocols, for example routing and switching.
The first data sending applications in modern time were telegraphy (1809) and teletypewriters (1906). The fundamental theoretical work in data sending and information theory by Harry Nyquist, Ralph Hartley, Claude Shannon and others during the early 20th century, was done with these applications in mind. Data sending is utilized in computers in computer buses and for communication with peripheral equipment via parallel ports and program ports such us RS-232 (1969), Firewire (1995) and USB (1996). The principles of data sending are also utilized in storage media for Error detection and correction since 1951. Data sending is utilized in computer networking equipment such as modems (1940), local area networks (LAN) adapters (1964), repeaters, hubs, microwave links, wireless network access points (1997), etc.
In ring networks, digital communication is utilized for transferring some sound calls over the same copper cable or fiber cable by means of Pulse code modulation (PCM), i.e. sampling and digitalization, in combination with Time division multiplexing (TDM) (1962). Telephone exchanges hit embellish digital and software controlled, facilitating some value added services. For example the first AXE ring exchange was presented in 1976. Since late 1980th, digital communication to the end user has been possible using Integrated Services Digital Network (ISDN) services. Since the end of 1990th, broadband access techniques such as ADSL, Cable modems, fiber-to-the-building (FTTB) and fiber-to-the-home (FTTH) hit embellish wide spread to small offices and homes. The underway tendency is to replace traditional telecommunication services by packet mode communication such as IP telephony and IPTV.
The first data sending applications in modern time were telegraphy (1809) and teletypewriters (1906). The fundamental theoretical work in data sending and information theory by Harry Nyquist, Ralph Hartley, Claude Shannon and others during the early 20th century, was done with these applications in mind. Data sending is utilized in computers in computer buses and for communication with peripheral equipment via parallel ports and program ports such us RS-232 (1969), Firewire (1995) and USB (1996). The principles of data sending are also utilized in storage media for Error detection and correction since 1951. Data sending is utilized in computer networking equipment such as modems (1940), local area networks (LAN) adapters (1964), repeaters, hubs, microwave links, wireless network access points (1997), etc.
In ring networks, digital communication is utilized for transferring some sound calls over the same copper cable or fiber cable by means of Pulse code modulation (PCM), i.e. sampling and digitalization, in combination with Time division multiplexing (TDM) (1962). Telephone exchanges hit embellish digital and software controlled, facilitating some value added services. For example the first AXE ring exchange was presented in 1976. Since late 1980th, digital communication to the end user has been possible using Integrated Services Digital Network (ISDN) services. Since the end of 1990th, broadband access techniques such as ADSL, Cable modems, fiber-to-the-building (FTTB) and fiber-to-the-home (FTTH) hit embellish wide spread to small offices and homes. The underway tendency is to replace traditional telecommunication services by packet mode communication such as IP telephony and IPTV.
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