We studied in the past few weeks some of the binary digital baseband modulation (OOK, 2PAM, and 4PAM). Today we have 8-Pulse Amplitude Modulation (8-PAM), which is another type of the binary digital baseband modulation. In 8PAM, we can transmit 3 bits using 8 different amplitudes. This is the 8PAM:
+7pt, +5pt, +3pt, +1pt, yt= -1pt, -3pt, -5pt, -7pt,
if [bo, b1, b2] = [000]
if [bo, b1, b2] = [001]
if [bo, b1, b] = [010]
if [bo, b1, b2] = [011]
if [bo, b1, b2] = [100]
if [bo, b1, b] = [101]
if [bo, b1, b] = [110]
if [bo, b1, b2] = [111]
Please write a complete MATLAB code to fulfill the following requirements:
(1) Assume we need to transmit a text string "Hello world" through a baseband communication system. Using 8-bit ASCII code, convert the string into digital data. Employing 8-PAM, convert the data bits into symbols. Assuming rectangular pulse shape, please plot the signal in the time domain with correct index.
(2) Develop an ideal baseband receiver to decode the data generated in the previous step (1).