| FM
FM stands for frequency modulation.
It is a means for transmitting audio or data information wirelessly.
Consider that very low frequencies such as audio, do not travel as
far as we would like. Higher frequencies can be transmitted better
for long distances. Therefore low frequencies such as audio and
data are modulated (combined with) higher frequencies in order to
transmit them long distances.
| So, then, how is audio information combined with
the higher carrier frequency in order to be transmitted?
In the case of FM - it is frequency modulation. The high
frequency carrier will have the low frequency information added
to it such that it seems to wiggle in frequency. By that
we mean that the carrier frequency will vary a little bit higher
and a little bit lower than its center frequency. The
amount of frequency that it changes is called "deviation". |
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Frequency Modulation |
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The
speed at which the frequency is changing is the speed of the audio
information that we are trying to transmit. For FM radio, there
should be no information in amplitude (or volume or amount of power)
changes as in AM wireless. All of the
information within FM is in frequency change.
At the receiver side, the receiver would adjust to receive the center
carrier frequency. The electronics would be sensitive to the rate
of change of that carrier frequency, and would then recover the audio
information that had been combined with the carrier frequency.
Once the audio information is recovered, it can then be amplified and
sent to speakers if desired. If it is data information instead,
then that data information is sent onto routers or computers as needed
for usage.
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