minimizing "chirp effect" w/ digital filters

[Garvacious]

Sorry if this question exposes my ignorance re: digital filtering, but I'm trying to get around the "chrip effect" I see with the LabVIEW Butterworth Filter vi in highpass mode (I am working w/ the Butterworth but I suspect this happens with all the filter types.)  What I am referring to is a large impulse signal that appears at the beginning of the filtered array-  how quickly it dampens off is related to the cutoff frequency chosen.  I have an array where I would like to see the filtered results of my signal without this low-frequency wave imposed upon it.  Is there any way around this or is this just a mathematical effect of digital highpass filtering?

[rpursley8]

The "ringing" you are seeing is due to your first point being non-zero.  The filter is responding to the first point going from zero to a non-zero value in one step.  If you want to eliminate this you can either:

1.  Be sure your waveform starts with a zero value, either by synching up the acquisition somehow or subtracting out the value of the first point from the waveform and then adding it back in after the filter.

or

2.  Use a window function to assure the first point is always zero.