I am a bit confused if the following signal is baseband or passband:
$f(t) = x(t) \cos(2 \pi f_c t) - j \: y(t) \sin(2 \pi f_c t),$ where $j = \sqrt{-1}$.
Since it is clearly not real, I cannot say it is passband. On the other hand, since it contains the frequency $f_c$, it should not be a baseband. Am I missing something?
Thanks,