Read the page on
Frequency Modulation.

The microphone converts
sound pressure wave to
electrical signals.
These audio voltages are
amplified by the audio
amplifier.
The amplified audio is
used to control the
deviation of the
frequency controlled
oscillator.
The oscillator frequency
is at the carrier
frequency, in the 88-108
MHz FM band.
The low power of the
frequency modulated
carrier is boosted by
the Radio Frequency
amplifier.
The aerial is driven by
the amplifier and
produces an
electromagnetic wave.
Under normal conditions
the transmitted signal
will travel as far as
the horizon. |