Physics · Ch 15 — Communication Systems
Introduction
Introduction
Introduction
Communication is the act of transferring information from one point (the sender) to another (the receiver), and it can only succeed when both share a common code or language to encode and decode the message. Human communication has evolved continuously - from prehistoric signalling and messengers to the electrical and electronic systems of the nineteenth and twentieth centuries, built on the work of pioneers such as Jagadish Chandra Bose, Samuel Morse, Guglielmo Marconi and Alexander Graham Bell.
Table 15.1 - Some Major Milestones in the History of Communication
| Year | Event | Remarks |
|---|---|---|
| Around 1565 A.D. | Delivery of a child reported to King Akbar using drum beats from a distant place | Minister Birbal is believed to have experimented with the number of drummers needed between the queen's location and the king's |
| 1835 | Telegraph invented by Samuel F.B. Morse and Sir Charles Wheatstone | Greatly increased the flow of messages through post offices and reduced the need for physical travel by messengers |
| 1876 | Telephone invented by Alexander Graham Bell and Antonio Meucci | Possibly the most widely used communication device in human history |
| 1895 | Jagadish Chandra Bose and Guglielmo Marconi demonstrate wireless telegraphy | Marked the shift from wire-based to wireless communication |
| 1936 | Television broadcast (John Logie Baird) | First television broadcast, by the BBC |
| 1955 | First radio FAX sent across a continent (Alexander Bain) | FAX transmission itself was patented by Alexander Bain as early as 1843 |
| 1968 | ARPANET, the first internet, is created (J.C.R. Licklider) | A U.S. defence department project; allowed file transfer between networked computers |
| 1975 | Fibre optics developed at Bell Laboratories | Fibre-optic systems are more efficient and economical than traditional wired systems |
| 1989-91 | Tim Berners-Lee invents the World Wide Web | Often described as a vast, round-the-clock encyclopaedia accessible to everyone |
With this history as backdrop, the chapter sets out to explain the basic building blocks of a communication system, why a message signal must be modulated before it can be transmitted, and how an amplitude-modulated wave is produced and detected.
| Year | Event | Remarks |
|---|---|---|
| Around 1565 A.D. | The reporting of the delivery of a child by queen using drum beats from a distant place to King Akbar. | It is believed that minister Birbal experimented with the arrangement to decide the number of drummers posted between the place where the queen stayed and the place where the king stayed. |
| 1835 | Invention of telegraph by Samuel F.B. Morse and Sir Charles Wheatstone | It resulted in tremendous growth of messages through post offices and reduced physical travel of messengers considerably. |
| 1876 | Telephone invented by Alexander Graham Bell and Antonio Meucci | Perhaps the most widely used means of communication in the history of mankind. |
| 1895 | Jagadis Chandra Bose and Guglielmo Marconi demonstrated wireless telegraphy. | It meant a giant leap - from an era of communication using wires to communicating without using wires. (wireless) |
| 1936 | Television broadcast (John Logi Baird) | First television broadcast by BBC |
| 1955 | First radio FAX transmitted across continent. (Alexander Bain) | The idea of FAX transmission was patented by Alexander Bain in 1843. |
| 1968 | ARPANET - the first internet came into existence (J.C.R. Licklider) | ARPANET was a project undertaken by the U.S. defence department. It allowed file transfer from one computer to another connected to the network. |
| 1975 | Fiber optics developed at Bell Laboratories | Fiber optical systems are superior and more economical compared to traditional communication systems. |
| 1989-91 | Tim Berners-Lee invented the World Wide Web. | WWW may be regarded as the mammoth encyclopedia of knowledge accessible to everyone round the clock throughout the year. |