The system in which information can be sent and receive
from one place to another is called a communication system.
Nowadays three types of communication systems are used:
(1)Electrical (2)Electronic (3)Optical
In every system of communication, there are three important parts : (i)Transmission (ii)Communication Channel (iii)Receiver
(i)Transmitter: The main function of a transmitter is to collect the signal produced by the source and to transmit it in a suitable form to a channel for sanding it to the receiver. if the output of a source is sound and so signal (sound signal).
Then it is converted into an electrical signal by a microphone (Transducer) before sending it. This is called an information (message) signal. So conversion of the main signal into a message signal is the main part of the process of the transmitter.
(ii)Communication Channel: Communication Channel is a physical medium that connects transmitter and receiver i.e. It provides a path between transmitter and receiver by which signal is communicated.
The communication channel is also called a medium link between transmitter and receiver. The form of the channel depends upon the type of communication system. This can be a form of wire or cable between transmitter and receiver or can be a wireless system.
When the signal to be transmitted propagates along the communication channel due to imperfection it is distorted and in the communication signal noise also gets superposed so a signal in distorted form is available.
(iii)Receiver: The main part of a receiver is to detect the signal to rebuild the received message and convert it into the main signal to be detected in its original form.
So that the message can be sent to receiving person, the primary function of the receiver is to receive the output of the channel and to convert it into a desirable signal i.e. to rebuild it into the main form.
Explanation: When a person wants to tell something to another person sitting near to him then he speaks something to tell him about something. The person who is speaking is the source of information and is a transmitter and sound waves are propagated in the air medium (channel).
The sound waves are the signal which is communicated by our medium to other people who listens to all signals. So Ears of the person who receives the sound are the receiver. This is the simplest form of communication system.
If the distance between the source (Transmitter) and receiver is very large then the signal gets weak before reaching to receiver i.e. the listener. In this case, the sound waves are converted into an electrical signals and with the help of wires are communicated to long distances.
The part by which sound waves are converted into electrical signals called the microphone (Transducer) converts electrical to a sound signal. When it is not possible to have contact between transmitter and receiver with the help of wire or cables in that case main signal first is converted into electrical signal and with the help of antenna is sent into the space.
The free space acts as communication channel and the signal is received by the antenna of receiver at a large distance. The received signal with the help of transducer and amplifier is converted into main signal.
Modes of communications :
(a) Point-to-point communication: in this mode, there is one transmitter and one receiver. In this, the message sent by a person by a transmitting media or by communication is given to the receiver. Example: The telephone system.
(b) Broadcast: In this there only one transmitter and there many receiver by so many receivers. In this one transmitter.
broadcasts the information or message and it is received by so many receivers. Example : Radio and Television.