Hey, we have began to touch a little on radio and amplitude modulation in my Electronics lab in college. Its very interesting to me, but I have some questions.
So we have this AM signal below called signal(t)
Here is the equation of how this happens.
signal(t) = A[1+B*message(t)]*cos(ωt) where the carrier wave is a cosine.
The carrier wave is in the middle. I understand how the carrier wave is mathematically forced to stretch and compress itself according to the amplitude of the message wave.
But what I don't understand is where is the frequency information of the message signal? Since the frequency of the carrier wave is constant, and only its amplitude changes, how does it retain the frequency of the message?
For example speech is composed of an infinite number of frequencies (fourier series). How does signal(t) retain these frequencies?
When demodulated, the message signal has to be unaltered (including its frequency content) so how does this happen?
Thank you very much. I already love radio. So interesting.
So we have this AM signal below called signal(t)
Here is the equation of how this happens.
signal(t) = A[1+B*message(t)]*cos(ωt) where the carrier wave is a cosine.
The carrier wave is in the middle. I understand how the carrier wave is mathematically forced to stretch and compress itself according to the amplitude of the message wave.
But what I don't understand is where is the frequency information of the message signal? Since the frequency of the carrier wave is constant, and only its amplitude changes, how does it retain the frequency of the message?
For example speech is composed of an infinite number of frequencies (fourier series). How does signal(t) retain these frequencies?
When demodulated, the message signal has to be unaltered (including its frequency content) so how does this happen?
Thank you very much. I already love radio. So interesting.