In the previous post, we discussed the impulse response. Impulse response h(n) is a digital system response in the time domain. But there is another characterization of the discrete system – frequency response H(ejω).
Frequency response can be calculated form impulse response by formula:
This means frequency response is the systems transfer coefficient to every frequency value. Frequency response is a complex function. So this can be evaluated as:
where |H(ejω)| – is amplitude frequency response
There are two simple ways to calculate the frequency response of a discrete system:
First mentioned above – from impulse response;
Second – from discrete system equation:
Lets say we have digital filter described as:
y(n)=-a1·y(n-1)+b0·x(n)
then frequency response of digital filter would be:
