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Explain pre-emphasis and de-emphasis concept in FM.
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Pre-emphasis:- In an FM system the higher frequencies contribute more to the noise than the lower frequencies. Because of this all FM systems adopt a system of pre-emphasis where the higher frequencies are increased in amplitude before being used to modulate the carrier. Pre-emphasis is a process which is used in transmitter side to boosting the amplitude of higher modulating signal before modulator. IF we used it after the modulator than carrier &modulator signal will mixed and it is difficult to verify which one is the modulating signal.

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De-emphasis: De-emphasis is process which is used in receiver side to reduce the signal & get their original signal. But it is used after demodulator circuit. Thus Pre-emphasis is used at transmitter and de-emphasis at receiver to improve the noise immunity

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Pre-emphasis/ De-emphasis graph:

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