When we multiply two complex signals in GNU Radio companion and see the result using WX FFT block then there is no frequency difference component(f1-f2) but only the addition component(f1+f2)...why is that??

on 2014-05-08 09:00

on 2014-05-08 10:20

On 08.05.2014 08:59, ali hanif wrote: > When we multiply two complex signals in GNU Radio companion and see the > result using WX FFT block then there is no frequency difference > component(f1-f2) but only the addition component(f1+f2)...why is that?? That is actually the mathematically correct thing. M

on 2014-05-08 10:42

Can you plz explain Martin or give me a link atleast...thnx in advance

on 2014-05-08 10:54

I think you are confused because you're doing the math on paper with real sin/cos functions. The complex signal sources produce complex oscillations ($s_f(t)=e^{j2\pi f t}$), which do not have symmetrical spectrum. Do the math with the exponential function; it get's easier than what you have to do to prove the real intermodulation signals, and you clearly see that $s_a s_b = s_{a+b}$. Greetings, Marcus