\documentclass{standalone}
%
\usepackage{tikz}
\usepackage{pgfplots}
\usepackage{xcolor}
\usepackage{fontspec}
\setmainfont{Montserrat}
%
\title{Effetto Doppler}
\begin{document}
	\tikzset{
		partial ellipse/.style args = {#1:#2:#3}{insert path={+ (#1:#3) arc (#1:#2:#3)}},
		human/.pic = {
			\draw [fill] (0,0) circle (0.3cm);
			\draw [thick] (0,0) circle -- (0,-1.5);
			\draw [thick] (-0.5,-1) -- (0,-0.5) -- (0.5,-1);
			\draw [thick] (-0.5,-2) -- (0,-1.5) -- (0.5,-2);
		},
		ambulance/.pic = {
			\draw [fill=red, thick] (4,0) -- (4.1,0.6) -- (4.5,0.6) -- (4.6,0) -- (4,0);
			\draw [fill=white, thick] (0,0) -- (5,0) -- (6,-3) -- (6.5,-3.2) -- (6.5,-4) -- (-1,-4) -- (0,0);
			\draw [fill=red, thick] (6.5,-3.7) -- (-0.92,-3.7) -- (-0.87,-3.5) -- (6.5,-3.5) -- (6.5,-3.7);
			\draw [thick] (-0.12,-0.5) -- (5.17,-0.5);
			\draw [fill=red, thick] (4,0) -- (4.1,0.6) -- (4.5,0.6) -- (4.6,0) -- (4,0);
			\draw [fill=blue!50!white] (4,-1) -- (5.1,-1) -- (5.6,-2.5) -- (4,-2.5) -- (4,-1);
			\draw [fill, thick] (5,-4) circle (0.6cm);
			\draw [fill=blue!70!white, thick] (5,-4) circle (0.3cm);
			\draw [fill, thick] (0,-4) circle (0.6cm);
			\draw [fill=blue!70!white, thick] (0,-4) circle (0.3cm);
		},
	}
	\begin{tikzpicture}
		\node at (3.5,9.5) {\textcolor{black}{\fontsize{23}{24}\selectfont Sorgente e ricevitore}};
		\node at (3.5,8.5) {\textcolor{black}{\fontsize{23}{24}\selectfont fermi}};
		\draw [color=blue!50!white, ultra thick] (4.2,0.6) circle (4cm);
		\draw [color=blue!50!white, ultra thick, dashed] (4.2,0.6) circle (5cm);
		\draw [color=blue!50!white, ultra thick] (4.2,0.6) circle (6cm);
		\draw [color=blue!50!white, ultra thick, dashed] (4.2,0.6) circle (7cm);
		\pic at (0,0) {ambulance};
		\begin{axis}[axis line style={draw=none}, tick style={draw=none}, yticklabels=\empty, xticklabels=\empty, xshift=6.65cm, yshift=-4cm, scale=0.8]%
			\addplot[domain=-1:3,samples=50,smooth,ultra thick,gray] {cos(deg((pi+0.3)*x))};
		\end{axis}
		\pic at (13,-2.5) {human};
		%
		\begin{scope}[shift={(20,0)}]
			\node at (3.5,9.5) {\textcolor{black}{\fontsize{23}{24}\selectfont Sorgente in movimento}};
			\node at (3.5,8.5) {\textcolor{black}{\fontsize{23}{24}\selectfont ricevitore fermo}};
			\draw [color=blue!50!white, ultra thick] (4.2,0.6) circle (4cm);
			\draw [color=blue!50!white, ultra thick, dashed] (3.7,0.6) circle (5cm);
			\draw [color=blue!50!white, ultra thick] (3.2,0.6) circle (6cm);
			\draw [color=blue!50!white, ultra thick, dashed] (2.7,0.6) circle (7cm);
			\pic at (0,0) {ambulance};
			\begin{axis}[axis line style={draw=none}, tick style={draw=none}, yticklabels=\empty, xticklabels=\empty, xshift=6.65cm, yshift=-4cm, scale=0.8]%
			\addplot[domain=0:2,samples=50,smooth,ultra thick,blue] {cos(deg((2*pi)*x))};
			\end{axis}
			\begin{axis}[axis line style={draw=none}, tick style={draw=none}, yticklabels=\empty, xticklabels=\empty, xshift=-6cm, yshift=-4cm, scale=0.8]%
			\addplot[domain=0:2,samples=50,smooth,ultra thick,red] {cos(deg((3/2 * pi)*x))};
			\end{axis}
			\pic at (13,-2.5) {human};
		\end{scope}
		%
	\end{tikzpicture}
\end{document}