\begin{tikzpicture}
\onslide<1-|handout:1>{
\begin{axis}[
	name=plot1,
	axis lines*=middle,
	enlargelimits = true,
	clip=false,
	scale only axis,
	width=0.7\textwidth,
	height=0.1\textwidth,
	ymin=0,
	ymax=3,
	xmin=-10,
	xmax=10,
	axis line style={->,>=stealth},
	xlabel={\small $\Omega$},
	ylabel={\small $X_c(j\Omega)$},
	every axis x label/.style={
		at={(ticklabel* cs:1)},
		%xshift=0.2cm,
		anchor=north,
	},
	every axis y label/.style={
		at={(ticklabel* cs:0.8)},
		anchor=south,
		xshift=0.6cm,
	},
	ytick=2,
	xtick=\empty,
	yticklabel={\small 1},
	xtick={-2.5, 2.5},
	xticklabels={\small $-\Omega_N$, \small $\Omega_N$},
	every outer y axis line/.append style={white!15!black},
	every y tick label/.append style={font=\color{white!15!black}},
	legend style={draw=white!15!black,fill=white,legend cell align=left}]
	\addplot[solid, line width=1pt] coordinates {(0, 2) (2.5, 0) (0, 0)};
	\addplot[solid, line width=1pt, fill=blue!50] coordinates {(0, 2) (-2.5, 0) (0, 0)};
\end{axis}
}
\onslide<2-|handout:1>{
\begin{axis}[
	name=plot2,
	at=(plot1.below south east), anchor=above north east,
	axis lines*=middle,
	enlargelimits = true,
	clip=false,
	scale only axis,
	width=0.7\textwidth,
	height=0.1\textwidth,
	ymin=0,
	ymax=1.5,
	xmin=-10,
	xmax=10,
	axis line style={->,>=stealth},
	xlabel={\small $\Omega$},
	ylabel={\small $S(j\Omega)$},
	yticklabel style = {yshift=0.1cm},
	every axis x label/.style={
		at={(ticklabel* cs:1)},
		%xshift=0.2cm,
		anchor=north,
	},
	every axis y label/.style={
		at={(ticklabel* cs:0.8)},
		anchor=south,
		xshift=0.5cm,
	},
	ytick={1},
	yticklabels={\small $\frac{2\pi}{T}$},
	xtick={-6, 0, 6},
	xticklabels={\small $-\Omega_s$, \small 0, \small $\Omega_s$}, 
	every outer y axis line/.append style={white!15!black},
	every y tick label/.append style={font=\color{white!15!black}},
	legend style={draw=white!15!black,fill=white,legend cell align=left}]
	\addplot[dirac, mark=triangle*, fill=black, mark options={scale=0.75, fill=black}, line width=1pt, domain=-6:6, samples=3] {1};
\end{axis}
}
\onslide<3-|handout:1>{
\begin{axis}[
	name=plot3,
	at=(plot2.below south east), anchor=above north east,
	axis lines*=middle,
	enlargelimits = true,
	clip=false,
	scale only axis,
	width=0.7\textwidth,
	height=0.1\textwidth,
	ymin=0,
	ymax=3,
	xmin=-10,
	xmax=10,
	axis line style={->,>=stealth},
	xlabel={\small $\Omega$},
	ylabel={\small $X_s(j\Omega) = \frac{1}{2\pi}X_c(j\Omega)\ast S(j\Omega)$},
	every axis x label/.style={
		at={(ticklabel* cs:1)},
		%xshift=0.2cm,
		anchor=north,
	},
	every axis y label/.style={
		at={(ticklabel* cs:0.8)},
		anchor=south,
		xshift=2.2cm,
	},
	xtick=\empty,
	ytick=2,
	yticklabels={\small $1/T$},
	xtick={-6, -2.5, 0, 2.5, 6},
	xticklabels={\small $-\Omega_s$, \small $-\Omega_N$, \small 0, \small $\Omega_N$, \small $\Omega_s$}, 
	every outer y axis line/.append style={white!15!black},
	every y tick label/.append style={font=\color{white!15!black}},
	legend style={draw=white!15!black,fill=white,legend cell align=left}]
	\addplot[solid, line width=1pt] coordinates {(0, 2) (2.5, 0) (0, 0)};
	\addplot[solid, line width=1pt, fill=blue!50] coordinates {(0, 2) (-2.5, 0) (0, 0)};
	\addplot[solid, line width=1pt] coordinates {(6, 2) (8.5, 0) (6, 0)};
	\addplot[solid, line width=1pt, fill=blue!50] coordinates {(6, 2) (3.5, 0) (6, 0)};
	\addplot[solid, line width=1pt] coordinates {(-6, 2) (-3.5, 0) (-6, 0)};
	\addplot[solid, line width=1pt, fill=blue!50] coordinates {(-6, 2) (-8.5, 0) (-6, 0)};
	
\end{axis}
}

\onslide<4|handout:1>{
\begin{axis}[
name=plot4,
at=(plot3.below south east), anchor=above north east,
axis lines*=middle,
enlargelimits = true,
clip=false,
scale only axis,
width=0.7\textwidth,
height=0.1\textwidth,
ymin=0,
ymax=3,
xmin=-10,
xmax=10,
axis line style={->,>=stealth},
xlabel={\small $\omega=\Omega T$},
ylabel={\small $X(e^{j\omega}) = X(j\Omega)$},
every axis x label/.style={
	at={(ticklabel* cs:1)},
	%xshift=0.2cm,
	anchor=north,
},
every axis y label/.style={
	at={(ticklabel* cs:0.8)},
	anchor=south,
	xshift=1.2cm,
},
xtick=\empty,
ytick=2,
yticklabels={\small $1/T$},
xtick={-6, -2.5, 0, 2.5, 6},
xticklabels={\small $-2\pi$, \small $-\Omega_NT$, \small 0, \small $\Omega_NT$, \small $2\pi$}, 
every outer y axis line/.append style={white!15!black},
every y tick label/.append style={font=\color{white!15!black}},
legend style={draw=white!15!black,fill=white,legend cell align=left}]
\addplot[solid, line width=1pt] coordinates {(0, 2) (2.5, 0) (0, 0)};
\addplot[solid, line width=1pt, fill=blue!50] coordinates {(0, 2) (-2.5, 0) (0, 0)};
\addplot[solid, line width=1pt] coordinates {(6, 2) (8.5, 0) (6, 0)};
\addplot[solid, line width=1pt, fill=blue!50] coordinates {(6, 2) (3.5, 0) (6, 0)};
\addplot[solid, line width=1pt] coordinates {(-6, 2) (-3.5, 0) (-6, 0)};
\addplot[solid, line width=1pt, fill=blue!50] coordinates {(-6, 2) (-8.5, 0) (-6, 0)};

\end{axis}
}
\end{tikzpicture}
