Butterworth filter shortcomings
Butterworth filter is a design classification of filters, similar to Chebyshev filter, it has high-pass, low-pass, band-pass, high-pass, band-stop and other filters. It has a stable amplitude-frequency characteristic inside and outside the passband, but has a long transition zone, which is easy to cause distortion in the transition zone. When calling the Butterworth filter in MATLAB, the signal will always be the first. The period is slightly distorted. But the amplitude-frequency characteristics in the future are very good.