Question

Sketch both, the time domain AM signal and its frequency spectrum and explain what you see in terms of themodulation property of the Fourier transform.(Hint: How is the frequency spectrum of the message signal(co-sinusoid of 880 Hz) plus a DC component in base band, i.e. before modulation?)

Answer 1

Answer:

see the attachment

Explanation:

In frequency spectrum there is no change in value of frequency of signal. However, The amplitude of signal after modulation increases. The fourier transform of sinwct is

1/2(F(w+wc) - F(w-wc))

For 2sinwct, the fourier transform is,

(F(w+wc) - F(w-wc))

In frequency domain, in AM only amplitude changes. Frequency remains same