Causal bandstop filter

1. What is a band stop filter used for?
2. What is the difference between Bandstop and Bandpass filter?
3. What makes a filter causal?
4. Is the ideal band-pass filter causal?

What is a band stop filter used for?

A Band Stop Filter, also sometimes called a notch or band reject filter allows a specific range of frequencies to not pass to the output, while allowing lower and higher frequencies to pass with little attenuation.

What is the difference between Bandstop and Bandpass filter?

A band-pass filter admits frequencies within a given band, rejecting frequencies below it and above it. Figure 8.3 shows the frequency response of a band-pass filter, with the key parameters labelled. A stop-band filter does the reverse, rejecting frequencies within the band and letting through frequencies outside it.

What makes a filter causal?

A filter is said to be causal if its output depends only on present and past inputs. Conversely, non-causal filters depend also on future inputs.

Is the ideal band-pass filter causal?

the filter is not causal, i.e. the impulse response h(n) is non zero for n<0; the impulse response has infinite duration.