For example, I want to feed a DC into a low pass filter. The the filter's first several output will not have the same DC value I want.
Does it mean that I need to dispose first several results?
How many shall I dispose?
What is the technical term describing this phenomenon, step response?
Does it only happen to DC or to other frequency signals as well?
Here comes sample code and diagram:
Fs = 64e3; f = 8e3; T = 1/Fs; t = 0:T:0.002; input = 0.002*cos(2*pi*f*t); input_with_DC = input+0.5; [b,a]=cheby1(1,2,0.4); output = filter(b,a,input_with_DC); plot(input_with_DC) hold plot(output,'r')
It can be seen from above diagram that the DC rises at first and then approach to the actual DC value.