An AM (DSB) signal is given by xe(t) = 20(1 + 0.5 cos(4000nt) + 0.5 cos(6000nt)) cos(20000nt). a) Sketch the frequency spectrum of x.(t). b) Find the average power content of each spectral component. c) Calculate the modulation index. d) Design a demodulator using block diagram and indicate the outputs of each block. e) Propose a method to reduce transmission bandwidth of the system.