can someone explain me these doubts?
it is a baseband signal representation. A- complex signal, R- real.
If I multiply baseband signal with FT( cos) then the signal will look like this ( on the plot the first on the left /For this case, convolution changes nothing). [![enter image description here]]
I shift the signal in frequency but my passband signal is still complex-valued, so it cannot be transmitted over a single channel ( Is it a reason why I can.t use multiplication with cos to modulate complex baseband signal?). otherwise, I will need two channels, one for the real part and one for the imaginary part.
if I multiply baseband only with FT(cos), why I get the same copy A-R in negative part and A-R in positive? In IQ modulation it is R-A in negative part and A-R in positive