Công thức tính tích chập:

$y(n)={\displaystyle \sum _{k=-\infty }^{\infty }x(k).h(k)}$

$y(n)={\displaystyle \sum _{k=-\infty }^{\infty }x(k).h(n-k)}$

$y(n)={\displaystyle \sum _{k=-\infty }^{\infty }x(k).h(n-k)}$

$y(n)={\displaystyle \sum _{k=-\infty }^{\infty }x(n-k).h(n-k)}$