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amplitude modulation & side bands

hi....
actually as per the definition the output of the amplitude modulation has same frequency as that of the carrier..........
bt if the frequency is constant then why are side bands supposed to be there?????
lokesh258
lokesh258 • May 31, 2012
because there is a distortion in the frequency component even though frequency is constant
lokesh258
because there is a distortion in the frequency component even though frequency is constant
then if a question is asked like this........what is the frequency of the modulated wave with modulating frequency f1 and carrier frequency f2??????????
is the answer f2 or f2+f1 and f2-f1??????
you cannot get a frequency on account of amplitude modulation. you will always get frequencies.

it is because amplitude modulation does not result in a single frequency component. rather three distinct components are produced.
The first component contains higher order frequency in terms of carrier frequency. this component is not useful because no message content resides in it.
the other two components are of interest to us since they contain message signal; these components are f2-f1 and f2+f1. it is from these two components that the message signal is recovered through various demodulation schemes.

so you always get a mixture of frequencies rather than a single frequency in the modulated wave as a result of amplitude modulation

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