Adding information to waves - P6

Bullet pointed information on adding information to waves.

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Coverting info into signals

  • All the time, information is being transmitted
  • Whatever type of info that you are sending, it will be coverted into electrical signals before it is transmitted
  • After this, it will be sent long distances down wire or on EM waves
  • There are two ways in which you can send info as waves - AM and FM
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AM

  • An AM radio transmitter sends out a continuous carrier wave
  • The signal is superimposed on the carrier wave using amplitude modulation:

Here, the sound wave from the music modulates the carrier wave by changing it's amplitude. Then the two waves combine so that the info is carrier by the pattern of the final wave's variation.

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FM

  • An FM radio transmitter sends out a continuous carrier wave
  • The carrier wave's amplitude isn't changed, but it's frequency

Where there is a peak in the signal wave, the frequency of the modulated wave is decreased. Where there is a trough in the signal wave, the frequency is increased

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FM

  • An FM radio transmitter sends out a continuous carrier wave
  • The carrier wave's amplitude isn't changed, but it's frequency

Where there is a peak in the signal wave, the frequency of the modulated wave is decreased. Where there is a trough in the signal wave, the frequency is increased

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Receivers

  • When a receiver detects a modulated wave, it will ignore the carrier part of the wave and extract the original signal
  • It is extracted from the pattern of the wave's variation
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