EVOLUTION OF MODERN COMMUNICATION

The history of modern electronic communications begun with Alexander Graham Bells telephone experiments, where speech was able to be converted into electrical energy, transmitted along physical wires and reconstructed at the receiver. Speech, which is actually vibration of the air, vibrated a paper cone to which a small coil was attached. This induced an electrical signal into the coil, which was proportional to the vibration of the paper cone. Alexander Graham Bell, born in Edinburgh, Scotland, 1847, emigrated to the United States, settling in Boston. Bell, interested in the education of deaf people, invented the microphone, and later, in 1876, an electrical speech machine, called the telephone. By 1878, Bell set up the first telephone exchange...

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   As the need to inter-connect telephone customers grew, they were connected via overhead wires to a central switching center, where the physical wires from each customer was connected to the physical wires of another customer via a manual operator. As more and more customers were connected, the need for more and more operators to connect calls were required. This quickly became unworkable, so development began on automating the connection process between customers, hence, automatic telephone switching exchanges became a reality and replaced local operators, who were still used to connect toll (long distance) calls. The customers wires from their home to the telephone switching center were overhead, installed in the same way as a...

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Radio Paging Systems

Radio Paging Systems:As a matter of fact, two persons are required for any form of human communication however, for good communication everyone needs to be contactable. Mobile radio is for communication with people on the move. Paging is a simple land mobile radio system to solve the all-times, all-places, all-people communication problems with very economic use of the radio spectrum, paging system can keep thousands of people in touch, with a small, light-weight, on obstructive, body-worm equipment. Present day paging developments are available with several innovative features and powerful message capabilities and are supported by nation-wide and are international transmitting and control facilities. Even in India, a sophisticated modern paging...

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Analog and Digital Communication

Analog and Digital communication:Analog communication is that type of communication in which message or information signal to be transmitted is analog in nature. This means that in analog communication the modulation signal is an analog signal. This analog message signal may be obtained from sources as speech, video shooting etc… In analog communication, the analog message signal modulates some high carrier frequency inside the transmitter to produce modulated signal.In digital communication, the message signal to be transmitted is digital in nature. This means that digital communication involves the transmission of information in digital form. Advantages of Digital Communication:The digital communication systems are simpler and cheaper compare...

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Classification of Communication Technology

Classification of Communication Technology:Regarding the mode of propagation, communication may be divided in the following two forms:Lines communication: In line communication, the medium of transmission is a pair of conductors called transmission line. This is also called as line as line channel. This means that in line also called as line communication, the transmitter and the receiver are connected through a wire or line. However, the installation and maintenance of a transmission line is not only costly and complex but also overcrowds the open space. Apart from this, its message transmission capability is also limited.Wireless communication: In wireless communication or radio communication, a message is transmitted through open space...

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Communication Channel

 1.Telephone channels:Telephone channels are based on circuits switching mechanism to establish an end to end communication link on a temporary basic. Telephone channels support only the transmission of electrical signal. Therefore appropriate transducers are used at the transmitting and receiving end of the channel. Further telephone channel are essentially a linear band width limited channel.2.Optical fiber:An optical fiber is a dielectric wave guide which transports light signals from one place to another. Just as a metallic wire pair or a coaxial cable. Just as a metallic wire pair or a coaxial cable transport electrical signal. There are numerous advantages of optical fibers.It has innermost potential bandwidth which is around 2*10^14Hz. Low...

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SOURCES OF COMMUNICATION TECHNOLOGY

A source of information may be characterized in terms of the signal which carries the information. Further, a signal is defined as a signal- valued function of time that plays the role of the dependent variable. At every instant of time, the function has a unique value. Speech:It is the primary method for human communication. Basically, the speech communication process involves the transfer of information from a speaker to a listener, which takes place in three successive stages as under:1.      Production: An intended message in the speaker’s mind is represented by a speech signal that consists of sounds generated inside the speaker’s mouth and whose arrangement is governed by the rules of language.2.     ...

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