I am trying to transmit a DQPSK Modulated Sequence into sky through
USRP, but after the symbols whose types are complex go through the pulse
shaping filter, how can we put them onto a carrier, say cos(2pifct).
Should we multiply the complex symbols with cos(2pifct) or with
exp(2pifc*t)? Should we sample the symbols after multiplying carrier
or before multiplying carrier? thank you!!!