M. Gieseking's dvisvgm
is the state-of-the-art utility for generating SVG from LaTeX input.
Unlike Inkscape it does not require intermediate PostScript. Moreover, it is part of TeXLive and MiKTeX.
SVG output:

Compile to SVG from LaTeX input with:
latex block-diagram
latex block-diagram
dvisvgm --exact --font-format=woff --zoom=-1 diagram
Embed (static) SVG into HTML using the <img>
tag:
<img src="https://url/of/block-diagram.svg">
File block-diagram.tex
, taken from the page linked in the question:
\documentclass{article}
\usepackage{pst-sigsys}
\pagestyle{empty}
\begin{document}
\begin{figure}[ht]
\centering %
\begin{pspicture}[showgrid=false](0.5,-1.2)(9,1.55)
%--- Define blocks ---
\rput(0.5,0){\rnode{s}{$s[n]$}}
\dotnode[dotstyle=square*,dotscale=0.001](1.7,0){dot}
\psblock(3,.75){H1}{$H_1(z)$}
\psblock(3,-.75){H2}{$H_2(z)$}
\psblock(5.8,.75){B2}{$\hat H_2(z)$}
\psblock(5.8,-.75){B1}{$\hat H_1(z)$}
\pscircleop(7.7,0){ominus}
\rput(9,0){\rnode{e}{$e[n]$}}
%--- Connect blocks ---
\psset{style=Arrow}
\ncline[nodesepA=.15]{-}{s}{dot}
\ncangle[angleA=90,angleB=180]{dot}{H1}
\ncangle[angleA=-90,angleB=180]{dot}{H2}
\ncline{H1}{B2} \naput[npos=.5]{$x_1[n]$}
\ncline{H2}{B1} \naput[npos=.5]{$x_2[n]$}
\ncangle[angleB=90]{B2}{ominus} \naput[npos=.5]{$z_1[n]$}
\ncangle[angleB=-90]{B1}{ominus} \naput[npos=.5]{$z_2[n]$}
\ncline[nodesepB=.15]{ominus}{e}
\end{pspicture}
\end{figure}
\end{document}