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Why orthogonal signals don't interfere?

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iVenky

iVenky

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I was learning about OFDM where it says that even though the signals are at the same frequency if they are orthogonal then they can be distinguished with each other at the receiver. How is this possible?

Thanks in advance.
 

simple

lets start with vectors in cartesian coordinate system, if you have a vector in X direction and make a dot product with a vector in Y direction the result will be zero

the same thing is applied to signals,but instead it is called signal space and its dimentions is infinity, but the dot product in signals is (multiply both signals and integrate) and is called cross correlation

if you apply that concept on,for example: F(t)=Acos(Wt) and G(t)= Bsin(Wt), the result will be zero although they have similar frequency and they are orthogonal
 
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How does the receiver distinguish two signals? I just couldn't understand how it does that?

Thanks in advance.
 

iVenky said:
How does the receiver distinguish two signals? I just couldn't understand how it does that?
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Receiver calculates inner products of received signal with each basis signal. For orthogonal signals inner product is equal 0. It is the first method (called correlation receiver), the second one is a bank of matched filters (filters which are matched for each basis signal). In fact both methods are very similar.
 

How does the receiver distinguish two signals?
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It depends on the modulation scheme. Clearly, the receiver must be synchronized to the carrier. And there must be a feature that allows to distinguish between both carrier phases respectively extract a reference phase You have to refer to a particular modulation scheme to see how the synchronization is performed.
 

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