A DSB modulated signal u(t) = m(t) cos4
fct is mixed (multplied) with a local carrier xL(t) = cos(4
fct +
) and the output is passed through a lowpass filter with a bandwidth equal to the bandwidth of the message m(t). The signal power at the output of the lowpass filter is denoted by Pout. The modulator signal power is denoted by Pu. Plot
as a function of
for