Editing Time-division multiplexing (section)

==History==
[[File:EB1922 Telegraph - Simplified Terminal Circuit of Multiplex Printer System.jpg|left|thumb|340x340px|Telegraphic multiplexer, from 1922 ''Britannica'']]
Time-division multiplexing was first developed for applications in [[Electrical telegraph|telegraphy]] to route multiple transmissions simultaneously over a single transmission line. In the 1870s, [[Émile Baudot]] developed a time-multiplexing system of multiple [[Hughes telegraph]] machines.

In 1944, the [[British Army]] used the [[Wireless Set No. 10]] to multiplex 10 telephone conversations over a [[microwave relay]] as far as 50 miles. This allowed commanders in the field to keep in contact with the staff in England across the [[English Channel]].<ref>[https://histru.bournemouth.ac.uk/CHiDE/Oral_History_of_Defence_Electronics/ws10_intro.htm Wireless Set No. 10]</ref>

In 1953, a 24-channel time-division multiplexer was placed in commercial operation by RCA Communications to send audio information between RCA's facility on Broad Street, New York, their transmitting station at Rocky Point and the receiving station at Riverhead, Long Island, New York. The communication was by a microwave system throughout Long Island. The experimental TDM system was developed by RCA Laboratories between 1950 and 1953.<ref>{{patent|US|2919308|"Time Division Multiplex System for Signals of Different Bandwidth"}}</ref>

In 1962, engineers from Bell Labs developed the first D1 channel banks, which combined 24 digitized voice calls over a four-wire copper trunk line between Bell [[telephone exchange|central office]] analogue switches. A ''channel bank'' at each end of the line allowed the single line to carry short portions, each {{frac|8000}} of a second, of up to 24 voice calls, in turn. The discrete signals on the trunk line carried 1.544&nbsp;Mbit/s divided into {{val|8000}} separate ''frames'' per second, each composed of 24 contiguous octets and one framing bit. Each octet in a frame carried a single telephone call in turn. Thus each of 24 voice calls was encoded into two constant-bit-rate streams of 64&nbsp;kbit/s (one in each direction), and converted back to conventional analog signals by the complementary equipment on the receiving end of the trunk line.<ref name="carriedo">{{cite web|url=http://www.dit.upm.es/infowin/atmeurope/CH2/atmbackg.html|title=ATM: Origins and State of the Art|author1=María Isabel Gandía Carriedo|date=31 August 1998|publisher=Universidad Politécnica de Madrid|archive-url=https://web.archive.org/web/20060623211435/http://www.dit.upm.es/infowin/atmeurope/CH2/atmbackg.html |archive-date=23 June 2006|access-date=2009-09-23}}</ref>