History of telecommunications

IICT-BAS

History of telecommunications Messaged carried by men, ship, animals Earliest distance communications - smoke signals

(North America and China) and drums (Africa, New Guinea and South America)

Europe - 1790s - fixed semaphore systems - information is conveyed by means of visual signals, using towers with pivoting shutters, also known as blades (paddles)

1792 – visual telegraphy (semaphore) between Lille and Paris

History of telecommunications 1809 - 'electrochemical' telegraph - German physician,

anatomist and inventor Samuel Thomas von Sömmering 1832 - electromagnetic telegraph - Baron Schilling,

Russia - short-distance transmission of signals between two telegraphs in different rooms, tested on a 5 km experimental underground and underwater cable

1833 - Carl Friedrich Gauss and Wilhelm Weber, Germany - communicate over a distance of 1200 m within Göttingen – achieve distant needle move in the direction set by the commutator on the other end of the line– developed signals, own alphabet encoded in a binary code

which was transmitted by positive or negative voltage pulses which were generated by means of moving an induction coil up and down over a permanent magnet and connecting the coil with the transmission wires by means of the commutator

History of telecommunications 1836 – David, American - the first known American

electric telegraph 1836 - the telegraph - developed by Samuel Morse (until

he was 34, he was a painter!) and Alfred Vail (USA) - transmitting over long distances using poor quality wire; Vail - developed the Morse code signaling alphabet with Morse

1837 - the first commercial electrical telegraph - Sir William Fothergill Cooke and Charles Wheatstone, England – patented as an alarm system; successfully demonstrated Euston and Camden Town (London)

History of telecommunications 1843 - U.S. Congress appropriated $30,000 to fund an

experimental telegraph line from Washington, D.C. to Baltimore

24 May 1844 - first public demonstration by Morse of his telegraph - a message from the Supreme Court Chamber in Washington to the B&O Railroad in Baltimore

1861 - the first transcontinental telegraph system (USA) 1866 - the first successful transatlantic telegraph cable

– between Ireland and Newfoundland – reduced communication time to a matter of a few hours,

allowing a message and a response in the same day !!!

History of telecommunications

1861 - Johann Philipp Reis, Germany - first telephone – couldn’t interest people in Germany in his invention

1876 – Alexander Bell Bell's patent 174,465, was issued to Bell on March 7

Elisha Gray also experimenting with acoustic telegraphy and files a patent application 3 hours after Bell with the U.S. Patent Office for a telephone - Bell got the patent

History of telecommunications 1878 Microphone Edison (General Electric) 1878 - First Telephone Exchange in New

Haven, USA - 21 listings Mid-1880s - telephone exchanges in every

major city of the United States 1832, James Lindsay (UK) - classroom

demonstration of wireless telegraphy; 1854, he demonstrated a transmission across the Firth of Tay from Dundee to Woodhaven (3 km), using water as the transmission medium

History of telecommunications

1884 Radio Telegraph Popov 1892 First Automatic Telephone Exchange in

La Porte USA by Strowger 1896 Radio Telegraph Marconi (Italy) 1898 First Automatic Telephone Exchange in

Germany 1901 Marconi - wireless communication

between Britain and Newfoundland, earned the Nobel Prize in physics in 1909

History of telecommunications

1918 Radio Carrier System /USA 1920 Radio Broadcasting

1925 John Baird, Scottish - demonstrated the transmission of moving silhouette pictures in London

1929 - Baird’s work formed the basis of semi-experimental broadcasts done by the British Broadcasting Corporation

History of telecommunications

1927 – demonstration of the cathode ray tube (CRT) in broadcasting of images – CRT inventor was Karl Braun in 1897

1930 Coaxial cables

1931 Radiolinks

1937 Pulse Code Modulation - PCM (64kbps)

Reeves (Bell Labs) - representation of a signal by a

series of digital pulses firstly by sampling the signal,

quantizing it and then encoding it – a method

developed in the seventies

History of telecommunications

1945 - Arthur C. Clarke – proposes the idea for

Synchronous Orbit Satellites

1946 Cellular Radio (Bell Labs) – remained

costly and not widely used until 1995

1947 Transistor (Bell Labs)

1957 Sputnik, USSR – first satellite

1962 – Telstar - first active, direct relay

commercial communications satellite

History of telecommunications

1960 – first LASER (Light Amplification by Stimulated

Emission of Radiation) Theodore Maiman , USA

1960 - AT&T installs first electronic switching system

in Morris, IL

1961 - Electronic Telephone Exchange (Bell Labs); T-

1 Carrier System (Bell Labs) TDM (Time Domain

Multiplexing) - 24 channels = 64 Kbps, 1.544 Mbps

(mega bits per sec)

History of telecommunications

1965 - AT&T introduces stored program controlled switching

1966 - Fibre Glass optics - Kao & Hockman, Standard Telecom Labs

1967 - Larry Roberts paper proposing ARPANET,

Advanced Research Projects Agency

1969 - The Department of Defense initiates the

ARPANet, which led to the development of

Internet - initially computers at Stanford

University and UCLA are connected

History of telecommunications 1969 ISDN (Integrated Services Digital Network

2x64k+16k)

1970 Aloha-network (Hawaii)

1974 Packet and Circuit Switched data networks

(CCITT X.25 and X.21) - International Telegraph and

Telephone Consultative Committee (CCITT,

from French: Comité Consultatif International Téléphonique et

Télégraphique)

History of telecommunications

1974 Arpanet/ Internet DoD/USA

1974 - Vint Cerf and Bob Kahn discuss connecting

networks together to form an "internet". They

collaborate in creating a Transmission Control

Protocol (TCP).

1976 Optical Fiber in data transmission

1977 Ethernet 10Mbps Xerox (developed in 1974),

Ether is the mysterious invisible fluid that transfers

heat, originally based on the ALOHA radio protocol

History of telecommunications

1972 Mobile Networks ARP

1978 ISO/OSI + CCITT x.200 (the standard describing

the OSI model) 1984 MHS (Message Handling System) CCITT/ISO

– ODA (Open Document Architecture) CCITT/ISO 1984 Intelligent Networks (AIN Series) Bellcore 1987 GSM (Groupe Special Mobile, CEPT) -

Global System for Mobile Communications

History of telecommunications

1987 - Bellcore introduces the Asymmetric Digital Subscriber Line (ADSL) concept which has the potential of multimedia transmission over the nation's copper loops

1989 HTTP/HTML in Cern by Tim Barners-Lee - Hypertext Transfer Protocol (a protocol i.e. set of procedures describing how to pass information) /HyperText Markup Language (language how to present information that passes via HTTP)

History of telecommunications

1991 - ATM (Asynchronous Transfer Mode 155 Mb/s)

1991 - IN CS.1 (Intelligent Networks) by ITU and ETSI

1992 - WWW (World Wide Web) - the first audio and video multicasts are broadcast over the Internet

1993 - Internet browser MOSAIC is introduced at the University of Illinois

History of telecommunications

1998 GPRS (General Packet Radio System) 2001 UMTS (Universal Mobile

Telecommunication System)

Terminal Complex First computer telecommunication systems -

early 60s: local multi-user systems - “terminal complex”

Classical Terminal Complex - shares computer resources among closely located users via telecommunication lines– Computer configuration (CPU / RAM / Channel

(usually phone line))– Transmission medium:

• wires/cables: pairs or cable set of pairs; twisted pairs for reduction of signal interference; coaxial cables (noise shield)

Terminal complex

CPU

RAM

I/O channel

I/O interface

Multiplexor

Telephone exchange

Link channels

Link channels

Terminal

–...

Modem

Modem

Modem

ModemModemModem

I/O system

Modem

Modem

Modem

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Information transmission methods:– Synchronous: byte-stream forming data blocks,

synchronization based on• additional signals in control lines • synchro-symbols in the front and in the end of the block advantage: higher speed, less communication overload drawback: more complicated hardware, buffer memory application: high speed communication

– Asynchronous: 1 start impulse and 1 or 2 stop impulse; clock frequency is higher than the read-write frequency (access instants) advantage: no buffering, simple synchronization circuit drawback: communication overload (30%) application: slow terminals in short distance

Terminal Complex

Information transmission modes:– Terminal complexes use mostly

phone/telegraph lines on • switched lines: use the public exchange by

dialed access from point to point advantage: chipper

drawback: slower, noisy

application: smaller traffic

• leased lines: fixed lines for monopoly use from point to point; connection line is owned of local PTT company

advantage: reliable error-free, faster, promptness

drawback: price

application: bigger traffic

Terminal Complex

Terminal Complex– Standard Interface

• usually bus of 30-60 signal lines• physical parameters: line length; signal

parameters (amplitude, frequency, working mode: monopoly, multiplex, block-multiplex); multiplexors’ number

– Multiplexor: • transforms parallel (byte) stream from terminals

to sequential (bit) stream for the channel interface

• addressing the terminals - 2 methods: cycle time-driven or event driven selection

• error control• same functions in opposite direction (from

channel to terminals)

Terminal Complex Modems (signal MODulator/DEModulator)

phone line transmission with digital to analog and analog to digital conversion

Structure and components:– Modulator (data input)– Demodulator (data output)– Filter (frequency separator)– Linear Amplifier

Modulation types– AM – FM – PhM

Modulations