4. Two real-valued baseband message signals, mi(t) and m(t), are transmitted simultaneously using the modulating system shown below. The spectra of m(t) and m(t) are also given. MO -5000 10 5000 - M malo -5000 10 50001 - 2 cos 40.000 2 cos 20,000 (a) Sketch the spectra of the signals at points a, b, and e in the block diagram. (b) What is the bandwidth of the signal at point c? (c) Design a receiver that will recover signals m. () and ma(e) from the signal at point c. Give your answer as a block diagram, and show that the receiver properly recovers the messages. SELECTED ANSWERS: In part (b), BW at point is 30kHz