In previous post we discussed about impulse response. Impulse response h(n) is digital system response in time domain. But there is another characterization of discrete system – frequency response H(ejω).
Frequency response can be calculated form impulse response by formula:
This means frequency response is 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
– phase frequency response.
There are two simple ways to calculate frequency response of 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:
