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