Question

2. (14 points) This problem shows an example of using the Fourier transform to analyze communication systems. The system in Figure 4, where (t)-f(t)+sin(wt) and has been proposed for amplitude modulation. f(t) + sin(o) Figure 4: System proposed for amplitude modulation. (a) (7 points) The spectrum of the input f(t) is shown in Figure 1, where 2mB o/100. Sketch and label the spectrum Y(w) of the signal y(t). Hint: You will need to use the frequency convolution property of the Fourier Transform to compute one of the terms of the spectrum you are to sketch (b) (7 points) It is desired to transmit the input signal (t) using double-sideband, suppressed carrier ampli- tude modulation (DSB/SC-AM). The system represented by the frequency response H(w) is a band-pass filter with the spectrum shown in Figure 5 Determine the range of wi and the range of w2 such that :(t) is the desired DSB/SC-AM transmission signal. H(o) 0 , Figure 5: Ideal bandpass filter, H(w).

Answer 1

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