The process of recovering the audio signal from the modulated surge is known as demodulation or detection.
Modulation is done to transmit the audio signal over larger distances
to a receiver.
When the modulated surge is pick up by the radio receiver,
it is necessary to recover the audio signal from it.
This process is fulfill in the radio receiver and is call demodulation.
Necessity of demodulation
It was note preliminarily that breadth modulated surge consists of
carrier and sideband frequentness.
The audio signal is contain in the sideband frequentness which
are radio frequentness.
If the modulated surge after modification is directly fed to the speaker as
shown in Fig-1,
no sound will be hear.
It's because diaphragm of the speaker isn't at each suitable
to respond to similar high frequentness.
Before the diaphragm is suitable to move in one direction,
the rapid-fire reversal of current tends to move it in the contrary direction i.e. diaphragm won't move at each.
Accordingly, no sound will be hear.
From the below discussion, it follows that audio signal must be separate from the carrier at a suitable stage in the receiver.
The recovered audio signal is also amplified and fed to the speaker for
conversion into sound.
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