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I have a signal magnitude and phase in frequency domain. I need to have it in time domain but I really have no idea how to do it. I heard something about mirroring the signal but I'm kinda new at this. I have tried to do something like this in matlab but I'm clearly missing the point. And how do I define the time vector?
z = A .* exp(i*phase);
X = ifft(z);
I've attached the signal plot https://i.stack.imgur.com/FfbTV.jpg
Okay, I don't use MATLAB, but I think this Python example represents what you may be asking.
import numpy as np A = 3 + 4j k = 5 N = 128 Z = np.zeros(N, dtype='complex') Z[k] = A Z[N-k] = np.conj( A ) z = np.fft.ifft(Z) print( z )
This will generate a real valued pure tone (all the imaginary values are zero to the limit of precision) signal with 5 cycles in the frame. The "mirroring" means that for a real signal the DFT is a conjugate mirror image, i.e. $Z[k] = Z^*[N-k]$. It is common convention to use X, but I like Z too.
zis your frequency domain vector, thenXis your time domain vector. Done! Where's the issue? $\endgroup$ – Marcus Müller Sep 10 at 19:33zis your frequency domain. There's really nothing ambiguous about that. It's kind of hard to help you understand the things you've read "somewhere" and understand what you seek when all you tell us what you don't seek. Please explain why this isn't what you need, and what you've read. $\endgroup$ – Marcus Müller Sep 10 at 20:15Xso that we can actually try to understand what you want? $\endgroup$ – Marcus Müller Sep 10 at 20:33