Why are OFDM Subcarriers Sinc Functions?

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Iain Explains Signals, Systems, and Digital Comms

Ай бұрын

Explains the relationship between the time domain OFDM transmitted signal, and the orthogonal subcarriers in the frequency domain.
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Пікірлер: 8

@theoryandapplication7197 19 күн бұрын

thank you very much,

@iain_explains 19 күн бұрын

You are welcome!

@pitmaler4439 Ай бұрын

The vector C_n represents just integer values of the base function f1 - ist that right? Or can use other step sizes e.g. f2 = 1.5*f1; f3 = 3*f1.....

@iain_explains Ай бұрын

They need to be integer, in order to maintain the orthogonality between the subcarriers. Hopefully this video explains it: "OFDM Waveforms" kzfaq.info/get/bejne/fJxyZ66qz5jWfKs.html

@AbhayNarasimhaKS Ай бұрын

2:04 If only the first element is nonzero, the output of IDFT has to be the DC value, not the sinusoid of fundamental frequency. The subcarriers range from C_0 to C_{N-1}. C_0 will correspond to the DC value at the output and C_1 will give the fundamental sinusoid of period = N. Please respond if I am wrong.

@iain_explains Ай бұрын

Yes, you're right. I simplified the diagram, only showing the elements of the vector that relate to the data-carrying sub channels.

@028gnanadathareddy4 Ай бұрын

@@iain_explains I did not understood how output of IDFT is sinusoidal with .output of IDFT will be all of same elements for given example right.

@iain_explains Ай бұрын

Try running these lines of code in Matlab: X=zeros(1,40); % Frequency domain vector X(2)=1; % Put data into the first subcarrier (only) ... note that X(1) corresponds to f=0 x=ifft(X); % Use IFFT to generate time domain signal stem(real(x)) % plot the time domain signal