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A signal contains components at 400 Hz and 2400 Hz This signal modulates a carrier of frequency 100 MHz. However, after demodulation, it is found that the 400 Hz signal component is present. The channel bandwidth is 15 kHz. What is the reason for the higher frequency signal not to be detected properly?

A signal contains components at 400 Hz and 2400 Hz This signal modulates a carrier of frequency 100 MHz. However, after demodulation, it is found that the 400 Hz signal component is present. The channel bandwidth is 15 kHz. What is the reason for the higher frequency signal not to be detected properly? Correct Answer Modulation used in FM but pre-emphasis is not used

In FM broadcasting, pre-emphasis improvement is the improvement in the signal-to-noise ratio of the high-frequency portion of the baseband.

In the process of detecting a frequency modulated signal, the receiver produces a noise spectrum that rises in frequency (a so-called triangular spectrum). This is the reason why a preemphasis is required.

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Without pre-emphasis, the received audio would sound unacceptably noisy at high frequencies, especially under conditions of low carrier-to-noise ratio, i.e., during fringe reception conditions.

Preemphasis increases the magnitude of the higher signal frequencies, thereby improving the signal-to-noise ratio.

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De-emphasis:

At the output of the discriminator in the FM receiver, a deemphasis network restores the original signal power distribution.

De-emphasis means attenuating those frequencies by the same amount by which they are boosted by the pre-emphasis.

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