Communication concepts
Communication is the process of transmitting information. It’s a big, vague, fuzzy word and broadly applied. The “Communications Department “ at a university may include speech teachers, public relations specialists, writers and broadcasters, who have nothing to do with hardware. By that definition , a writer is in the communication business.
Evolution of communications
We the human beings are communicating from early days that is by drawing the pictures on cave walls. It can be how to attack the animal or how to the save the life from the threats or it may be a route to go to another cave.
The earlier long-distance communications was by signal fires that relayed simple information. The signal used to represent “yes” or “no” – the question being asked had to be known beforehand. It’s only a single bit information, not a detailed message.
A written letter or a human messenger could carry more information. The first systems we might call telecommunications were series of hilltop towers, built by French engineer Claude Chappe in the 1790s. The towers had to be in sight of each other, with an operator in each one. The operator relayed a message by moving arms on top of the tower. The operator of the next tower looked through a telescope to watch the arms move, reading the message, recording it, then moving the arms of his tower to relay it to the next tower. Chappe invented a code that used arm position to indicate letters or certain common words. His system was called an optical telegraph.
Samuel Morse’s electrical telegraph eventually replaced Chappe’s optical one. It also required operators, but they used keys that completed an electrical circuit, sending bursts of currents through a wire. The Morse code was a series of dots an dashes ( short and long pulses) that represented letters.
The electrical telegraph spread across the continents and in 1866 across the
Later Alexander Graham Bell developed telephone. He borrowed some principles from the telegraph , but instead of transmitting dots and dashes, it sent a continuously changing electrical current that represented a speaker’s voice. The telephone network was bigger and more complex than the telegraph network.
After that radio waves are used to carry signals through air. Radio first carried telegraph signals. Wires worked fine on land, but only radio could send telegrams to ships at sea and relay urgent messages such as request for help. It was radio rescue calls that sent ships to help the survivors of the sinking of the Titanic. Radio communications started for ships and airplanes in the world war II.
Radio communication started at low frequencies, but gradually moved to higher ad higher frequencies as electronics improved. The higher the frequency the more information the signal can carry. Pictures need more transmission capacity than sound alone, so television are broadcast at higher frequencies than audio radio.
By the 1970s , satellites were beaming radio signals around the globe. The telephone system had become global and known popularly “telecommunication network” . We could make phone calls to anywhere in the world.
After that fiber optics arrived. Fiber provides high bandwidth. It carries high capacity information at faster rate. Now it is a integral part of telecommunication network.
