Translations:Frequency response of a digital system/11/en

of a stable digital system exists in a region that includes the unit circle. If we substitute $Z=e^{-i\omega \Delta t}$ into the transfer function $H\left(Z\right)$, we obtain the frequency response $H\left(e^{-i\omega \Delta t}\right)$. That is, the values of H(Z) on the unit circle make up the frequency response of the system. Instead of the cumbersome notation $H\left(e^{-i\omega \Delta t}\right)$, the frequency response is written more conveniently as $H\left(\omega \right)$. Thus, we have