\begin{tikzpicture}
\begin{axis}[
	name=plot1,
	axis lines*=middle,
	enlargelimits = true,
	clip=false,
	scale only axis,
	width=0.8\textwidth,
	height=0.2\textwidth,
	ymin=0,
	ymax=1,
	xmin=-3.2,
	xmax=3.2,
	axis line style={->,>=stealth},
	xlabel={\small $\Omega$},
	ylabel={\small $X(j\omega)$},
	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=0.6cm,
	},
	ytick=\empty,
	xtick={-1.5, 1.5},
	xticklabels={\small $-1.5\pi$, \small $1.5\pi$},
	every outer y axis line/.append style={white!15!black},
	every x 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] coordinates {(-1.5, 0.5) (1.5, 0.5)};
\end{axis}

\begin{axis}[
	name=plot2,
	at=(plot1.below south east), anchor=above north east,
	axis lines*=middle,
	enlargelimits = true,
	axis on top=true,
	clip=true,
	scale only axis,
	width=0.8\textwidth,
	height=0.2\textwidth,
	ymin=0,
	ymax=1,
	xmin=-3.2,
	xmax=3.2,
	axis line style={->,>=stealth},
	xlabel={\small $\omega=\Omega T$},
	ylabel={\small $X(e^{j\omega})$},
	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,
	},
	xtick={-2, -1, 0.5, 1, 1.5, 2},
	xticklabels={\scriptsize $-2\pi$, \scriptsize $-\pi$, \scriptsize $0.5\pi$, \scriptsize $\pi$, \scriptsize $1.5\pi$, \scriptsize $2\pi$},
	ytick=\empty,
	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[ycomb, mark=*, fill=black, mark options={scale=0.75, fill=white}, line width=1pt] coordinates {(-1.5, 0.5) (1.5, 0.5)};
	\only<2-|handout:1>{
	\addplot[ycomb, blue2, mark=*, fill=black, mark options={scale=0.75, fill=white}, line width=1pt] coordinates {(0.5, 0.5) (3.5, 0.5)};}
	\only<3-|handout:1>{
	\addplot[ycomb, red2, mark=*, fill=black, mark options={scale=0.75, fill=white}, line width=1pt] coordinates {(-0.5, 0.5) (-3.5, 0.5)};}
	
\end{axis}
\end{tikzpicture}
