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Basic of Communication




A radio communication system send signals by radio
Types of radio communication systems deployed depend on technology, standards, regulations, radio spectrum allocation, user requirements, service positioning, and investment.
The radio equipment involved in communication systems includes a transmitter and a receiver, each having an antenna and appropriate terminal equipment such as a microphone at the transmitter and a loudspeaker at the reciever in the case of a voice-communication system.


With the technology of the early twentieth century, radio communication systems required:

The production of radio frequency alternating electrical energy at a transmitting station. Alternating currents are set up in the transmitting circuit, of suitable frequency and of great intensity (or high voltage). This insures a high rate of variation of the interlinked electrostatic and electromagnetic fields and a great magnitude of these variations.
The radiation of this energy into space. The transmitting circuit is given a shape suitable for producing fields extending to great distances and generally in the direction of the receiving circuits more than in other directions.
The absorption of a portion of this electromagnetic energy at the receiving stations and its transformation into some form of energy capable of affecting some one of the human senses. The receiving circuit is given such a shape and position as to page link it with as large a proportion of the field of the transmitting circuit as possible.

In modern systems, systems transmission intensity is sometimes very small. The power consumed in a transmitting station varies depending on the distance of communication and the transmission conditions. The power received at the receiving station is usually only a tiny fraction of the transmitter's output, since communication depends on receiving the information, not the energy, that was transmitted.