Faithful transmission of information from one place to another place is called communication.
Optical fibers are used in optical communication.
Fig: Communication system
A communication system contains three main parts:-
(i) Transmitter: It process and encode the information and make it suitable for transmission.
The message signal for communication can be analog signals or digital signals.
An analog signal can be converted suitably into a digital signal and vice-versa.
[An analog signal is that in which current or voltage value varies continuously with time.
A digital signal is a discontinuous function of time. Such a signal is usually in the form of pulses.]
(ii) Communication Channel: The medium through which information propagate from transmitter to receiver is called communication channel.
(iii) Receiver: It receives and decode the signal.
A signal in which current or voltage changes its magnitude continuously with time, is called an analog signal.
A signal in which current or voltage have only two values, is called a digital signal.
Note An analog signal can be converted suitable Into a digital signal and vice-versa.