File talk:Vsa block.PNG

Spectrum after I/Q?

Vector signal analysers would typically display a spectrum by doing an FFT on the IF, not the IQ. After IQ, any spectrum would be after subtraction of the LO, so wouldn't necessarily show the mask of the signal.

And the IQ diagram is from before modulation. Indeed, if the constellation for QAM is poor, there would be limited scope for modulation at all. Chumpih ^t 21:51, 20 February 2024 (UTC)