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path: root/doc/thesis/figures/tikz/qam-example.tex
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% vim: set ts=2 sw=2 noet:

%% TODO: finish this figure

\begin{tikzpicture}
	% Draw digital signals
	\begin{scope}[font = \ttfamily\footnotesize, text = blue!70!white]
		\node[above = 1mm of M, xshift = 2mm] {\(\ldots 1100101\)};
		\node[above = 7mm of vmi, xshift = 3mm]
			{\(\overbracket[.8pt]{\,11\ldots 00\,}^{\sqrt{M} \text{ bits}}\)};
	\end{scope}

	% Draw analog waveform
	\begin{scope}[font = \ttfamily\tiny]
		\coordinate (O) at ($(mi)+(-2mm,10.5mm)$);

		\node[left, red!70!white, anchor = east, text width = 8mm, align = right]
			at ($(O) + (-2mm,0)$) {\(2^{\sqrt{M}}\) levels};

		\foreach \y in {-3mm,0,3mm} {
			\draw[gray, densely dotted] (O) ++(-2mm,\y) -- ++(22mm,0);
		}

		\draw[thick, draw = red!70!white] (O)
			-- ++(3mm,0) -- ++(0,-3mm) -- ++(3mm,0) -- ++(0,6mm)
			-- ++(3mm,0) -- ++(0,-3mm) -- ++(3mm,0) -- ++(0,-3mm)
			-- ++(3mm,0) -- ++(0,3mm)  -- ++(3mm,0);
	\end{scope}

	% Draw constellation diagram
	\begin{scope}
		\coordinate (O) at ($(S)+(-7mm,8mm)$);
		\draw[gray, -latex] (O) ++(-2mm,0) -- ++(12mm,0) node[right] {\tiny \(\phi_i\)};
		\draw[gray, -latex] (O) ++(0,-2mm) -- ++(0,12mm) node[above] {\tiny \(\phi_q\)};

		\node[
			circle, thick,
			minimum size = 3pt,
			inner sep = 0, outer sep = .8pt,
			draw = gray, fill = red!50!white
		] (P) at ($(O)+(5mm, 4mm)$) {};

		\node[gray, above right] at (P) {\tiny \(s\)};

		\draw[gray, densely dotted]
			(P) -- (P |- O)
			(P) -- (P -| O);
	\end{scope}
\end{tikzpicture}