4 Design an 8-level PAM for binary data transmission. We can use the following pulses in the zero ISI pulse generator: (i) raised cosine pulse with roll-off factor of 0.6; (ii) full-width rectangular NRZ pulse. (a) Generate and compare the two baseband signal waveforms (for 40 random PAM symbols). (b) Generate the eye diagrams of the two signals. (c) Numerically compute estimates of the autocorrelation functions for the two PAM signals. Plot the results to compare against the analytical results given in Sec. 6.7. (d) Estimate the power spectral densities of the two signals by applying both the autocorrelation method and the Welch method