What is Demodulation or Detection? – Need of demodulation:

Demodulation or detection is a process of recovering the original modulating signal (intelligence) from the modulated carrier wave i.e., the demodulation is a process reverse of the process of modulation.

Need of demodulation:

The wireless signals transmitted from a transmitter consist of RF carrier waves and audio frequency signal waves. If the modulated wave is directly fed to the loudspeaker, no sound will be heard from the loudspeaker. This is because of the simple reason that the frequency of the carrier wave is very high and the loudspeaker diaphragm cannot respond to such high frequencies due to large inertia of their vibrating discs etc.

Neither will such RF waves produce any effect on human ear as their frequencies are much beyond the audible frequencies (20 Hz to 20 kHz approximately). Hence it becomes essential to separate the audio frequency signal (intelligence) from the modulated carrier wave.