I have a 16-QAM constellation, then I divide it into imaginary part and real part. I convolve both by Srrc pulse and multiply by cos(2*pifct) and -sen(2*pifct). Let's say fc equal to 40 MHz Now, we have my signal in +-40 MHZ. If I want displace to 3 MHz, Can I multiply simply by cosine? And, if then I wish to move to baseband, I must multiply by cosine and sine? Sorry for the long question.