lecture 1: Introduction to Telecommunications

Chia sẻ: Do Xuan | Ngày: | Loại File: PDF | Số trang:6

Thêm vào BST

Báo xấu

139
lượt xem 24
download

lecture 1: Introduction to Telecommunications

Mô tả tài liệu

Download Vui lòng tải xuống để xem tài liệu đầy đủ

Telecommunications refers to long-distance communication (the Greek tele means "far off"). At present, such communication is carried out with the aid of electronic equipment such as the Radio, Telegraph, Telephone, and Television. In earlier times, however, smoke signals, drums, light beacons, and various forms of semaphore were used for the same purpose. The information that is transmitted can be in the form of voice, symbols, pictures, or data, or a combination of these. The physical equipment for a telecommunications system includes a transmitter, one or more receivers, and a channel or means of communication such as the air, water, wire,...

Chủ đề:

Bình luận(0) Đăng nhập để gửi bình luận!

Lưu

Nội dung Text: lecture 1: Introduction to Telecommunications

CSN200 Introduction to Telecommunications, Winter 2000 Lecture_01 Introduction to Telecommunications CSN200 This course introduces students to modern data communications, including standards, techniques, applications and devices involved in interconnecting computers in both local and wide area networks. Reference: Business Data Communications and Networking, 6th Edition, by- Fitzgerald and Dennis. Data Communications: Data Communications is the movement of computer information (digitized information) from one point to another by means of electrical, electromagnetic or optical transmission systems. Data communications usually includes only data. Telecommunications: Telecommunications is a broader term which includes the transmission of voice, graphics, images and video as well as data. Dictionary Meaning of the Word Telecommunication: Tele means distance Telecommunication means distant communication Telecommunications refers to long-distance communication (the Greek tele means "far off"). At present, such communication is carried out with the aid of electronic equipment such as the Radio, Telegraph, Telephone, and Television. In earlier times, however, smoke signals, drums, light beacons, and various forms of semaphore were used for the same purpose. The information that is transmitted can be in the form of voice, symbols, pictures, or data, or a combination of these. The physical equipment for a telecommunications system includes a transmitter, one or more receivers, and a channel or means of communication such as the air, water, wire, cable, communications satellite, or some combination of these. lecture 1.doc Page 1 (6)
CSN200 Introduction to Telecommunications, Winter 2000 Lecture_01 Why Study Data Communications and Communications Network? To fulfill the occupational need of the society: • In 1800s most countries were agricultural societies - needed farmers • In 1900s many countries had become industrial societies - labours • As we approached 2000s we have moved into an information society, where the strategic resource is information that must flow on communication network - dominated by computers, data communications, networking and related highly skilled individuals To reduce the Information lag: • Information lag is the time it takes for information to be disseminated around the world. We will discuss: • History of Data Communications in North America • The Changing Nature of Information Systems History of Telecommunications: Compiled from: Communications page by a group of German students: http://www-stall.rz.fht-esslingen.de/telehistory/welcome.html History timeline by America's Public Broadcast Services: http://www.pbs.org/wgbh/pages/amex/technology/techtimeline/ The history of communication begun in 3500BC using Abstract Signs, where paper was made from palm trees and ink was made from oil and soot. And the History of Telecommunication begun in 490 BC using messenger (40 kilometers long run). One of the most famous events of "telecommunications" was the Marathon Run. In September 490 BC a terrible battle was going on at the coast of the Aegean Sea, near the town of Marathon. A small well armed Greek army fought against a numerically stronger army of Persians, but nevertheless the Greeks gained victory. The leader of the Greek army sent a courier with the message of victory back to Athens. After the messenger had completed the more than 40 kilometers long run and reached the streets of Athens, he collapsed with the words: "Be glad! We are the winners!" ... and died. At that time fire signals were also used for communication. lecture 1.doc Page 2 (6)
CSN200 Introduction to Telecommunications, Winter 2000 Lecture_01 360 BC : Water telegraphs store detailed information transmitted by smoke signals 150 BC : Net of smoke telegraphs over 3000 miles all across the Roman Empire 1794 : C. Chappe (France) develops an optical telegraph with its own alphabet 1809 : Electric telegraph by Samuel T. von Sömmering, Germany (35 wires) 1840 : Samuel F. B. Morse (USA) develops Morse code and improves telegraph 1844 : Electrical switch (relay) automatically writes transmitted information Samuel F.B. Morse demonstrates his telegraph by sending a message to Baltimore from the chambers of the Supreme Court in Washington, DC. The message, "What hath God wrought?" marks the beginning of a new era in communication. 1850 : Telegraphy expands over national borders: sea cable England-France 1853 : Telegraph wires used in both directions simultaneously (duplex mode) 1861 : Philipp Reis, a German teacher, invents the telephone 1876 : Alexander Graham Bell (USA) take out patents for telephones Scottish-American psychologist born 03. 03. 1847, Edinburgh died 02. 08. 1922, Baddeck (Nova Scotia, Canada). First he was deaf and dumb teacher, later he dealt with transformation of sound in electrical variations and vice-versa, developed the first usable telephone (1876). Alexander Graham Bell patents his telephone, built with the assistance of young self-trained engineer Thomas A. Watson. Elisha Gray, who developed a similar device at about the same time, unsuccessfully challenged Bell's patent. 1886 : Punched cards store census data in the USA for processing 1892 : Telephone uses dial, first automatic telephone exchange (no operator) 1894 : Wireless transmission of signals over two miles by the Italian physicist and engineer Marconi Marconi began in 1894 with experiments on wireless transmission of radiowaves. In 1899 he sent information for the first time across the English Channel, in 1901 he bridge over the Atlantic with his wireless telegraphy. In 1909 he became Nobel Prize winner (with Braun). 1899 : Head of US Patent Office says: "Everything possible has been invented." 1902 : World wide radio communication on ocean ships (Morse code) 1906 : Electronics era begins: rectifier, triode, thermionic valve amplifier, etc. 1917 : AM transmitter: Modulation of a carrier frequency using speech signal 1919 : Binary memory (toggle switch) built of two triodes 1922 : Broadcasting stations commercialized (Russia, France, England, USA) 1928 : Mechanical Television Baird Mechanical Television was broadcasting. 1927 : Electronic Television Philo Farnsworth demonstrates the first electronic television for potential investors by lecture 1.doc Page 3 (6)
CSN200 Introduction to Telecommunications, Winter 2000 Lecture_01 broadcasting the image of a dollar sign. Farnsworth receives backing and applies for a patent, but ongoing patent battles with RCA will prevent Farnsworth from earning his share of the million-dollar industry his invention will create. 1935 : Electronic Television Philo Farnsworth and Vladimir Zworykin separately made great advances toward commercial television and affordable sets. 1928 : Frequency modulation (FM) - higher sound quality for broadcasting 1931 : First electronic transmission of television images in Berlin 1935 : Multi-wire coaxial cables for communication purposes 1939 : Digital computer John Atanasoff and Clifford Berry of Iowa State College complete the prototype of the first digital computer. It can store data and perform addition and subtractions using binary code. The next generation of the machine will be abandoned before it is completed due to the onset of World War II. 1949 : Printed circuit boards for cheaper and easier placement of components 1951 : Howard H. Aiken develops large electromagnetic computer 1954 : Transistor radio, stereo recording, 76 meter radio telescope in England 1964 Operating System IBM rolls out the OS/360, the first mass-produced computer operating system. Using the OS/360, all of the computers in the IBM 360 family could run any software program. Already IBM is a giant in the computer industry, controlling 70% of the market worldwide. 1965 Minicomputer Digital Equipment introduces the PDP-8, the world's first computer to use integrated circuit technology. Because of its relatively small size and its low $18,000 price tag, Digital sells several hundred units. 1970 Optical Fiber Corning Glass announces it has created a glass fiber so clear that it can communicate pulses of light. GTE and AT&T soon begin experiments to transmit sound and image data using fiber optics, which will transform the communications industry. 1976 Super Computer Cray Research, Inc. introduces its first supercomputer, the Cray-1, which can perform operations at a rate of 240,000,000 calculations per second. Supercomputers designed by Seymour Cray will continue to dominate the market; the Cray 2, marketed in 1985, will be capable of 1,200,000,000 calculations per second. 1979 : Japanese Matsushita Inc. takes out a patent for Liquid Crystal TV screen 1980 : Videotext, Cable Television, Video Conferencing, Compact Disc 1983 : Personal Computers, Floppy Disks as storing device PC's have taken the world by storm, dramatically changing the way people communicate; IBM dominates the personal computer market, benefiting both from the production of its own machines as well as "clones" produced by other companies. 1985 : Satellite navigation (both military and civilian applications) lecture 1.doc Page 4 (6)
CSN200 Introduction to Telecommunications, Winter 2000 Lecture_01 1990 : Hubble Telescope The space shuttle Discovery deploys the Hubble Space telescope 350 miles above the Earth. Although initial flaws limit its capabilities, the Hubble will be responsible for numerous discoveries and advances in the understanding of space. History of Communications in North America: • 1837 Samuel Morse - Telegraph • 1843, Alexander Bain - Printing Telegraph • 1876, Alexander Graham Bell - Telephone • 1874, Alexander (Sandy) Graham Bell developed the concept of the telephone at his father's home in Brantford, Ontario. • 1876, developed the first telephone capable of transmitting understandable conversion. First long distance call was made from Paris, Ontario to Brantford, Ontario. • 1879, Manual switchboards; automatic switching • Digital switching and digital circuits emerged in the 80's and 90's. • 1948, First commercial Microwave link for telephone was in Canada • 1962, First international satellite telephone over Telstar • 1962, Fax was introduced • 1963, Touch tone telephones • 1969, Picture phone service • 1969, Internet began as a network of US military and academic computers • 1976, packet-switched network for computer data • 1984, Breakup of AT&T (1885 - 1984), Increasing competition • 1983, newer cellular telephone networks • 1996, Deregulation Act, Open competition lecture 1.doc Page 5 (6)
CSN200 Introduction to Telecommunications, Winter 2000 Lecture_01 In Canada • In the early days, Bell Canada and CN/CP Telecommunications built competing telephone systems from coast to coast, using microwave circuits supplemented by satellite circuits supplied by Telesat Canada. Teleglobe Canada provided all of the international circuits. • Bell Canada is dominant in Ontario and Quebec but most other provinces have their own telephone systems which dominate their own areas. (Alberta, BC, NB, Manitoba etc.) • CN/CP became Unitel and all of the other common carriers, led by Bell banded together as Telecom Canada to compete with Unitel. Telecom Canada became the Stentor Group. Recently many US carriers have moved into Canada to compete for long distance services and AT&T bought into Unitel. • Coast to coast fibre optic cable circuits now form the backbone of the Canadian telecommunications system, although satellite (Telstar, 1962) and microwave (first 1948) still play important roles. The Changing Nature of Information Systems • In the 1950's, batch processing with paper tape and punched cards. • 1960's saw the development of online terminals using asynchronous serial connections to computers at low speeds and real-time transaction processing systems requiring communication across telephone lines. • 1970's saw the replacement of many older discrete file systems with database management systems where queries and data entry could occur remotely. • With the rise of the microcomputer in the 1980's came the need to exchange data between microcomputers, and between micros and mainframes, giving rise to LAN technology. • With the rise of computing power on the desktop the older paradigm which had a powerful mainframe computer supplying computing power to essentially dumb terminals gave way to distributed computing and client/server computing. In client/server systems, applications are divided up among a network of computers where server processes are providers of services and clients are consumers of services. Information Superhighway A large-scale communications network providing a variety of often interactive services, such as text databases, electronic mail, and audio and video materials, accessed through computers, television sets, etc. Also called data highway Common Carrier A public service or public utility company, as a telephone or telegraph company, engaged in the transmitting of messages for the public. Also called carrier. In other countries they are known as Public Telephone and Telegraph services. lecture 1.doc Page 6 (6)