Newbie level 5
I want to build a low-pass filter that has no or very minimal lag in time domain (in other words, I want to use it for data smoothing, responsive to big changes in the data, but still good at filtering out noise). In order to do this, I think it's a requirement that the filter has 0 phase. I have heard that a causal filter for doing this is not possible. Can anyone point me to the closest known approximations for this filter?