Analog Communication

 Introduction

Communication is the process of establishing connection or link between two points for information exchange.

        The electronic equipment which are used for communication purpose, are called communication equipment. Different  communication equipment when assembled together form a communication system. The typical examples of communication system are line telephony and line telegraphy, radio telephony and radio telegraphy, radio broadcasting, point-to-point communication and mobile communication, computer communication, radar communication, television broadcasting, radio telemetry, radio aids to navigation, radio aids to aircraft landing etc.

The Communication Process

The fundamental purpose of an electronic communication system is to transfer information from one place to another . Thus, electronic communication can be summarized as the transmission, reception and processing of information between two or more locations using electronic circuits. the original source information can be in analog form, such as the human voice or music, or in digital form, such as binary-coded numbers or alphanumeric codes.

Block diagram of communication system

Information Source

                We know that a communication system serves to communicate a message or information. This message or information originates in the information source. In general, there can be various messages in the form of words, group of words , code, sound signals etc. However, out of these messages, only the desired message is selected and conveyed or communicated.

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.

Transmitter

      The function of the transmitter is to process the electrical signal from different aspects. 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 function of the transmitter.

The Channel & the Noise

           The term channel means the medium through which the message travels from the transmitter to the receiver . In other words, we can say that the function of the channel is to provide a physical connection between the transmitter and the receiver. During  the process of transmission and the reception the signal gets distorted due to noise introduced in the system . Noise is an unwanted signal which tend to interfere with the required signal.

Receiver

        The main function of the receiver is to reproduce the message signal in the electrical form from the distorted received signal. This reproduction of the original signal is accomplished by a process known as the demodulation or detection . Demodulation  is the process of modulation carried out in transmitter.

Output Transducer

        The output transducer is used to convert an electrical message signal into its original form. For example in radio broadcasting , the destination is a loudspeaker which works as a transducer i.e., it converts  the electrical signal in the form of original sound signals.