ELEMENTS OF COMMUNICATION TECHNOLOGY

The main purpose of a communication system is to transmit an information bearing signal from a source, located at one point, to a user or destination, located at another point some distance away. Figure below shows the block diagram of a general communication system in which the different functional elements are represented by blocks.

1. Information source :

A communication system serves to communicate a message or information. This message or information originates in the information source. I n general, there can be various messages in the form of words, groups of words, code, symbols, sound signal etc…However, out of these messages only the desired message is selected and conveyed or communicated. In short, we can say that the function of information source is to produce required message which has to be transmitted.

      

2. Input transducer :

A transducer is a device which converts one form of energy into another form. The message from the information source may or may not be electrical in nature. In a case when the message produced by the information source is not electrical in nature, an input transducer is used to convert it into a time varying electrical signal. For example, in case of radio broad casting, a microphone converts the information or message which is in the form of sound waves into corresponding electrical signal.

3. Transmitter :

The function of the transmitter is to process the electrical signal from different aspects. For example in radio broad casting the electrical signal obtained from sound signal, is processed to restrict its range of audio frequencies and is often amplified. In wire telephony no real processing is needed. However, in long –distance radio communication or broadcast, signal amplification is necessary before modulation. Modulation is the main function of the transmitter. In modulation, the message signal is superimposed upon the high frequency carrier signal. In short, we can say that inside the transmitter, signal processing such as restriction of range of audio frequencies, amplification and modulation are achieved. All these processing of the message signal are done just to ease the transmission of the signal through the channel.