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Why Can't Sidebands Overlap

In amplitude modulation of carrier wave, upper and lower sidebands are created. Now suppose two radio stations have carrier frequencies very close to each other. My textbook states that it is essential that the sidebands of the radio stations don't overlap. However, we don't really tune into the sidebands right? The only thing we care about is the carrier frequency. As long as the carrier frequency doesn't overlap with sidebands, I don't see a reason why sidebands of two waves can't overlap.
Other way round, the modulation is the thing you're interested in... the sidebands are containing all the information and the carrier wave just gets thrown away by the reciever.

if it was music stations with overlapping sidebands you'd hear two different songs mixed together - which is usually undesirable
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esrever
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Original post by Joinedup
Other way round, the modulation is the thing you're interested in... the sidebands are containing all the information and the carrier wave just gets thrown away by the reciever.

if it was music stations with overlapping sidebands you'd hear two different songs mixed together - which is usually undesirable


So you mean that sidebands are used by receivers to obtain the transmitted data instead of carrier wave? Why is that the case?
Original post by esrever
So you mean that sidebands are used by receivers to obtain the transmitted data instead of carrier wave? Why is that the case?

well the sidebands are where the data is... the carrier on it's own has no data. if the carrier isn't being modulated you don't get sidebands. you only get sidebands if the carrier is being modulated.

when you amplitude modulate a carrier with an audio frequency you end up with new frequencies which are the sum of the frequencies and the difference between the frequencies.

if the carrier was 1MHz and the audio was 1kHz you'd get 1001000Hz (upper side band) and 999000kHz (lower side band) as well as the carrier being broadcast.
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esrever
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Original post by Joinedup
well the sidebands are where the data is... the carrier on it's own has no data. if the carrier isn't being modulated you don't get sidebands. you only get sidebands if the carrier is being modulated.

when you amplitude modulate a carrier with an audio frequency you end up with new frequencies which are the sum of the frequencies and the difference between the frequencies.

if the carrier was 1MHz and the audio was 1kHz you'd get 1001000Hz (upper side band) and 999000kHz (lower side band) as well as the carrier being broadcast.


Thank you so much for clarification :smile:

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