对于制作此框图有什么想法吗？

Question

绘制此框图的一些想法：

我只有这个：

    \documentclass[tikz,border=2mm]{standalone}
\usetikzlibrary{positioning,arrows.meta}

\begin{document}
    \begin{tikzpicture}[block1/.style={draw, minimum width=3cm, minimum height=1.8cm},
    block2/.style={draw, minimum width=1cm, minimum height=.8cm},
    >=Stealth]
    \node[block1] (b1) {1};
    \node[block1, right=5cm of b1] (b2) {2};
    \draw[->] (b1.east)--node[above] {c} (b2.west);
    \draw[->] (b2.east)--++(0:1cm) node[right] {exit};
    \end{tikzpicture}
\end{document}

谢谢！！！

Answer 1

尝试

    \documentclass[tikz,border=2mm]{standalone}
\usetikzlibrary{arrows.meta,calc,positioning}

\begin{document}
    \begin{tikzpicture}[
    block/.style={draw, minimum width=22mm, minimum height=8mm},
   sum/.style={circle, draw, minimum size=6mm, inner sep=0pt,
               node contents={\huge$+$}},
  mult/.style={circle, draw, minimum size=6mm, inner sep=0pt,
               node contents={\huge$\times$}},
            >=Stealth,
node distance=12mm and 6mm]
\node (b1) [block]              {$h_1[n]$};
\node (b2) [block,below=of b1]  {$h_2[n]$};
    \coordinate[left=of $(b1.west)!0.5!(b2.west)$] (in);
    \coordinate[left=of $(b1.east)!0.5!(b2.east)$] (out);
\node (m)  [mult, right=of b2];
\node (s)  [sum,right=of out -| m.west];
\node (b3) [block,right=of s]   {$h_3[n]$};
%
\draw[<- ] (in) -- node[above] {$x[n]$} + (-12mm,0);
\draw[<->] (b2.west) -| (in) |- (b1.west);
\draw[->]   (b1) -| (s);
\draw[->]   (b2) -- (m);
\draw[->]   (m)  -| (s);
\draw[->]   (s)  -- (b3);
\draw[->]   (b3.east)  -- node[above] {$y[n]$} + (12mm,0);
    \end{tikzpicture}
\end{document}