I just looked at my post again, maybe I should have inserted to the first "If you downconvert to zero Hertz".. without using I Q donconversion ... Frank
> A purely real signal has a frequency spectrum that is symmetric. (If > you do a Fourier transform, the left half plane is a mirror copy of > the right half plane). If you downconvert to zero Hertz a RF signal at > the carrier frequency where the right and left of the carrier > frequency are asymetric, you get corruption. > > For a IQ downconversion sampling, the signal's frequency spectrum is > not constrained to be symmetric. The frequency spectrum at the carrier > frequency is simply shifted down to 0 Hz. > Frank >
