Basic Communication System
A basic communication system consists of an information source, a transmitter, a link, and a receiver (Fig. 1).
The idea/message that is to be conveyed is information. The message may be individual one or a set of messages. It may be a symbol, code, group of words, or any pre-decided unit.
In radio transmission, the transmitter consists of a transducer, modulator, amplifier, and transmitting antenna (Fig. 2).
Transducer: Converts sound signals into electric signal.
Modulator: Mixing of audio electric signal with high frequency radio wave.
Amplifier: Boosting the power of modulated signal.
Antenna: Signal is radiated in the space with the aid of an antenna.
The function of communication channel is to carry the modulated signal from transmitter to receiver. The communication channel is also called transmission medium or link.
The term channel refers to the frequency range allocated to a particular service or transmission.
A receiver consists of the following components (Fig. 3):
Pickup antenna: To pick the signal
Demodulator: To separate out the audio signal from the modulated signal
Amplifier: To boost up the weak audio signal
Transducer: To convert back audio signal in the form of electrical pulses into sound waves.