Does baseband signal has negative frequency? In wiki baseband signal means that can include frequencies that are very near zero. I wonder whether baseband signal has negative frequency.
Thank your answers..
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If a signal is real valued, then it will have negative frequencies when represented by complex-exponential Fourier transforms.
But if you use the trigonometric Fourier series representation you do not need a negative frequency concept.
If the signal is complex valued, such as an analytic signal, it may or may not have negative frequencies when represented by complex-exponential Fourier transforms.
It might help to watch my YouTube video explaining negative frequency: https://youtu.be/gz6AKW-R69s
I'm a professor and I've been building what I think of as an on-line video textbook for Signals, Systems, and Digital Communications.