Telecommunication defined as the communication over large distances by cable, telegraph, telephone, radio or more precisely telecommunication is the transmission of signals over vast distances for the purpose of communication.
The need to communicate or connect is as old as civilization itself. Mankind in all ages have evolved their own means of communication. In the past ages communication over distances was essentially of three kinds,
The pounding of drums in seemingly impenetrable forests alerted various tribes to invaders or other dangers. Mainly the natives of Africa, New Guinea and tropical America practiced drum telegraphy.
Fire signals were used by the Greeks and Romans usually to signal a military defeat. Fires were lit from mountain to mountain, tower to tower. Smoke signals were used by Indian tribes and Romans, mostly in battle. Runners carried messages from one place to another usually on foot. The first recorded legend of a runner is of Pheidippides a Greek soldier who ran from the town of Marathon to Athens in 490 BC to announce the Persian’s defeat in the Battle of Marathon. It is said that he ran the entire distance without stopping but moments after delivering his message he dropped dead due to exhaustion.
Homing pigeons carrying messages date back to 6000 years. These pigeons flew upto 40 miles a day. The first message bearing pigeon was thought to be loosed by Noah. The Egyptians and Persians used carrier pigeons. Genghis Khan established a pigeon relay post across Asia and much of Eastern Europe. Pigeons were used till World War II to carry messages across enemy lines.
In 1838 telegraph, the first modern instrument used in sending messages to a distant place in a short interval of time was invented. In 1844 Samuel Morse introduced his distinctly new language, the Morse Code. The first long distance telegraph message was sent between Baltimore and Washington. The telegraph era came to an end after World War II
Telephone was a logical step after the telegraph, since both are wire based electrical systems. Telephone is the first telecommunication mode that drastically revolutionized the lives of ordinary people. The telephone enabled people to speak to each other when they are physically apart over large distances. It is essentially a device that converts sound, specifically human voice into electrical signals of various frequencies, which the receiver then converts back into the original voice. The first telephone message was sent as early as 1876(from one room to another consisting of seven words). By 1890 many cities had primitive telephone systems. The first Trans-Atlantic phone cable was installed in 1959. The first official Trans-Atlantic message(90 words) took 60 minutes to cross the ocean. The first Trans-Atlantic fiber-optic cable was laid in 1988 called TAT-8 and it carried 40,000 telephone circuits. Some subsequent optic cables include TAT-9(1992, 80,000 telephone circuits) and TAT-12(19996, 300,000 telephone circuits)
The advent of radio and then television shrunk the world getting people closer and simplified the process of obtaining news and information. Marconi is credited with the invention of radio. He sent and received his first radio signal in Italy in 1895. This was possible by the discovery of electro magnetic waves or radiations prior to 1895. These waves are produced by rapidly changing electric and magnetic fields or by rapidly oscillating charged particles like electrons. These radiations can travel in vacuum with a maximum speed of three lakh kilometer’s per second. Since the radiations do not require wires to travel, the radio was originally called ‘wireless telegraph’. The first wireless transatlantic transmission was made in 1901. The discovery of the photoelectric effect paved the way for the invention of the television.
Messages are converted into electrical signals. These signals are fixed to an electromagnetic wave of suitable high frequency. These electromagnetic waves are called radio-frequency carriers. They carry the messages. In case of radio, the range of the carrier frequency is 300KHz to 30MHz. For television the frequency range of the carrier waves is 30MHz to 300MHz. When an audio (sound) or video (light) frequency messages are superimposed on these carrier waves, the carrier waves are said to be modulated. These modulated waves are transmitted into space with the help of powerful transmitters and travel over long distances. When they strike an aerial of a radio or an antenna of a television alternating currents are set up which are sent to the receiver. In the receiver the selected modulated wave is fed to a detector circuit, where the sound or image is separated from the carrier wave. This is called de-modulation. This separated signal is sent to an amplifier, which enables one to hear the sound or image.
The field of telecommunication further progressed by the advent of computers. A computer is a fast acting device, which can accept large amount of input data, store it in its memory and produce the result in the form of an output. But it was the Internet, which revolutionized telecommunication, shrinking borders and effectively transforming the world in to a global village. The Internet is a global communication network connected by fiber optic cabling that transmits data by packet switching via the standard Internet Protocol. The origin of the Internet lies in the creation of APRANET(Advanced Research Projects Agency Network) a project of the U.S Department of Defense in 1968. Rapid progress in technology saw the APRANET undergo various modifications till two decades later it ceased to exist and the Internet came into being. By the mid nineties the World Wide Web burst on the scene and since then nothing has remained the same.
By the end of the nineties the Internet had one million hosts and computers were nine times faster. The Internet has allowed commerce and collaboration and interaction between individuals across man-made boundaries.
Telecommunication is now recognized as a key factor in the development of social, economic, commercial and cultural activities. It is a billion-dollar industry providing services and jobs to thousands of people.
The progress of science has enabled people to see, hear and communicate with each other from different corners of the world, hitherto inaccessible regions have become accessible and in a twinkling of an eye information is obtained. Maybe in the not so distant future telecommunication will come to mean communication in space, between planets and perhaps with life forms in distant galaxies.