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Cool goIITian

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21 Feb 2007 23:15:22 IST

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What is the meaning of frequency deviation in FM wave and what is the use of it??

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Asvin Vaidyanath

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22 Feb 2007 10:01:44 IST

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refer the link

http://en.wikipedia.org/wiki/Frequency_modulation

Hari haran

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22 Feb 2007 12:33:36 IST

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It refers to frequency modulation.

In order to send information signals to long distances they are superimposed on high frequency waves known as carrier waves.This process is called modulation.There are three types for this:-

1. Amplitude Modulation (AM)

2. Frequency Modulation(FM)

3. Phase Modulation (PM)

If the eqn of carrier wave is taken as

y = Asin(2

)

In AM, the waves are superimposed in such a way that 'A' undergoes a periodic variation in accordance with the frequency of the info. signal.

In FM,

undergoes variation and in case of PM,

undergoes variation.

Bipin Dubey

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24 Feb 2007 00:51:31 IST

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Frequency deviation (?f) is used in FM radio to describe the maximum instantaneous difference between an FM modulated carrier frequency, and the nominal carrier frequency. The term is sometimes mistakenly used as synonymous with frequency drift, which is an unintended offset of an oscillator from its nominal frequency.

The frequency deviation of a radio is of particular importantance in relation to bandwidth, because less deviation means that more channels can fit into the same amount of frequency spectrum. The FM broadcasting range (88-108 MHz) uses a channel spacing of 200 kHz, with a maximum frequency deviation of 75 kHz, leaving a 25 kHz buffer above and below the center frequency to reduce interaction with other channels AM broadcasting uses a channel spacing of 10 kHz, but with Amplitude modulation frequency deviation is irrelevant.

FM applications use peak deviations of 75 kHz (200 kHz spacing), 5 kHz (25 kHz spacing), 2.25 kHz (12.5 kHz spacing), and 2 kHz (8.33 kHz spacing).

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