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\textref h:C v:C
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\textref h:C v:C
\htext (3.34 -0.79){$x(t)$}
%end textellipse
%begin textellipse

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\textref h:C v:C
\htext (2.31 -0.26){$w(t)$}
%end textellipse
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\textref h:C v:C
\htext (5.38 -0.28){$v(t_i)$}
%end textellipse
%begin textellipse

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\textref h:C v:C
\htext (6.13 -0.78){$z(t_i)$}
%end textellipse
%begin textellipse

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\textref h:C v:C
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\textref h:C v:C
\htext (3.34 -3.34){$\hat x(t_i|t_{i-1})$}
%end textellipse
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\textref h:C v:C
\htext (0.53 -2.81){$u(t{i-1})$}
%end textellipse
\end{texdraw}
\end{center}