a. Sketch |X (ω)|, the amplitude spectrum of a signal x (t) = 3 cos 6πt + sin 18πt + 2 cos(28 - ∉)πt, where ∉ is a very small number → 0. Determine the minimum sampling rate required to be able to reconstruct x (t) from these samples.
b. Sketch the amplitude spectrum of the sampled signal when the sampling rate is 25% above the Nyquist rate (show the spectrum over the frequency range ±50 Hz only). How would you reconstruct x (t) from these samples?