6 TCO 4 Why do we perform deemphasis on the demodulated sign

6. (TCO 4) Why do we perform de-emphasis on the demodulated signal in an FM receiver? (Points : 10)

Solution

In audio signal transmission SNR>1 at low frequencies and SNR>1 at high frequencies.So,the high frequencies of the audio signal will not be reproduced and signal fidelity decreases. To improve the fidelity(acquiring of signal at receivers) Pre-emphasis technique is used at tansmitter before modulation.After pre-emphasis,high frequency components amplitude increases.

De-emphasis technique is inverse process of Pre-emphais technique.De-emphasis is used to attenuate the high frequency components which were enhanced at transmitter side before modulation.To do so signal to noise ratio comes to a normal level.