(i) Modulation: Modulation is the process of combining the low-frequency signal with a very high-frequency radio wave called carrier wave (CW).
The resulting wave is called a modulated carrier wave. This job is done at the transmitting station.
(ii) Demodulation: It is the process of separating or recovering the intelligent (low frequency) signal from the modulated carrier wave.
(iii) Unmodulated carrier: When the characteristics of the carrier are yet to be varied in accordance with the signal or intelligence to be conveyed, it is referred to as unmodulated carrier.
(iv) Selectivity: Is the ability of a receiver or reject unwanted signal and accept the
desired signal.
