Re: Scaling cutoff freq of Butterworth filter


lemon wrote:
Dear group,

I am currently using a butterworth lowpass filter for filtering sets of
parameter files.
For this purpose, I found an "optimal" cutoff frequency to generate the
filter.
I have, however, the necessity of changing the "sampling rate" of the
parameter set, but at the same time get the "same" results in time.

Your use of terminology is a bit different from the standard one.
Usually, one applies the Butterworth filter to a data set, not
a parameter set.

So, is there any method of scaling the cutoff parameter of the filter
accordingly to the changes in the "sampling rate"?

Yes, there is. If you look up "IIR filter design" in most DSP
textbooks,
there is a section on frequency transforms. Among those transforms is
an LP -> LP transform that changes the cutoff frequency of an LP
filter.

Rune

.