LIB > signals > filters > iir-1 > butterworthIIRFilter

butterworthIIRFilter(order, type, freq, sampfreq)

import signals.filters.iir-1

Design Butterworth digital IIR filter.

orderthe order of the filter
typethe type of the filter ("lowpass", "highpass", "badpass", "bandstop"). See description.
freqcorner frequency/frequencies. See description.
sampfreqif given, the sample frequency of the signal. If not, analog filter will be designed.
return valueTransfer function object.

Parameter type is a string value describing the filter type:

The meaning of parameter freq depends on the type of the filter. If it is a bandpass or bandstop filter, then it is an array of frequencies, otherwise it is a single frequnecy.

For more information, see http://en.wikipedia.org/wiki/Butterworth_filter.

import signals.filters.iir-1;
Design digital Butterworth filter
filt=butterworthIIRFilter(4, "", 100Hz[100Hz,200Hz], 600Hz)
import signals.filters.iir-1;
Design analog Butterworth filter
filt=butterworthIIRFilter(4, "", 100Hz[100Hz,200Hz])
import signals.filters.iir-1;
Plot filter characteristics
filt.plot()