3.8 Consider a message signal m(t) with the spectrum shown in Figure P3.8. The message bandwidth W = 1 kHz. This signal is applied to a product modulator, together with a carrier wave A cos(2nfet), producing the DSB-SC modulated signal s(t). The modulated signal is next applied to a coherent detector. Assuming perfect synchronism between the carrier waves in the modulator and detector, determine the spectrum of the detector output when: (a) the carrier frequency f = 1.25 kHz and (b) the carrier fre- quency f = 0.75 kHz. What is the lowest carrier frequency for which each component of the modulated signal s(t) is uniquely de- termined by m(t)? M() -WOW 0 Figure P3.8