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One characteristic of the FM process is that the noise is distributed such that it's lowest at the bottom frequency of the channel, and increases steadily as you move up the channel. Knowing this, pre- and de-emphasis is the clever trick we use to decrease the noise in the FM communications channel. Here's how it's done:

At the transmitter, pre-emphasis is applied to the baseband information before modulation ... the main channel L+R and L-R signals, plus any subcarriers that the station carries. Pre-emphasis is intentional distortion of the frequency response across the baseband that attenuates the low-frequency end, and progressively amplifies everything as you move up in frequency. The result of this operation is what actually gets transmitted.

The receiver is responsible for doing just the opposite. It applies de-emphasis immediately after demodulation ... it attenuates the high-frequency end of the baseband, and progressively amplifies everything as you move down in frequency.

If the pre- and de- are accurately matched, then the frequency response of the system winds up flat across the baseband, which is what we want. But ... by attenuating the higher frequencies, the receiver also changes the noise-content of the baseband, from a distribution that gets worse as you move up in frequency, to a distribution that's flat across the channel.

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What is pre-emphasis and de-emphasis in FM?

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What is a standard FM receiver IF?

A standard FM receiver typically uses an intermediate frequency (IF) of 10.7 MHz. This frequency is standardized for FM broadcasting to allow for effective demodulation and filtering of the received signal. The use of a fixed IF helps in improving selectivity and sensitivity in the receiver design, enabling clearer audio reproduction of the FM signal.


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Related Questions

What is pre-emphasis and de-emphasis in FM?

In FM, the effect of noise is more on higher frequencies when compared with low frequencies. Therefore in order to have high signal-to-noise ratio(low noise), the high frequencies are amplified at the transmitter side and for compensation deemphasis(decreasing the amplitude of those boosted frequencies ) is done at receiver.


What are the types of FM receiver?

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When was Hot FM network created?

Hot FM network was created in 1990.


When was The Heart FM Network created?

The Heart FM Network was created in 1994.


What is a standard FM receiver IF?

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When was Life FM - radio network - created?

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What is intermediat frequency of FM radio receiver?

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