Our course has been using the book Introduction to Communication Systems by Upamanyu Madhow for our communications course. There is a question in the book on page 87 Software lab 2.1 which is

Consider a pair of independently modulated signals, $u_c(t) = \sum_{n=1}^{n=N} b_c[n]p(t − n)$ and $u_s(t) = \sum_{n=1}^{n=N} b_s[n]p(t−n)$, where the symbols $b_c[n], b_s[n]$ are chosen with equal probability to be $+1$ and $-1$, and $p(t) = I_{[0,1]}(t)$ is a rectangular pulse. Let N = 100.

Use Matlab to plot a typical realization of $u_c(t)$ and $u_s(t)$ over 10 symbols. Make sure you sample fast enough for the plot to look reasonably “nice.”

I want to ask what is the meaning of plotting $u_c(t)$ and $u_s(t)$ over 10 symbols.

Link for the book - https://www.ece.ucsb.edu/wcsl/Publications/intro_comm_systems_madhow_jan2014b.pdf


$10$ symbols means that you choose $N=10$, i.e., you plot realizations of




in the range $t\in[0,10]$.

  • $\begingroup$ I wonder why they say "Let N = 100" yet ask to realize the signal over 10 symbols in the following sub-part of the problem. Seems like a good way to confuse the reader. $\endgroup$ – Envidia Jan 27 '20 at 17:02
  • $\begingroup$ @Envidia: This might only be the first part of a longer exercise, who knows. Anyway, they ask for a plot of 10 symbols, so that's what has to be done. $\endgroup$ – Matt L. Jan 27 '20 at 17:06

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