de.gsi.math.filter.iir

Class Butterworth

java.lang.Object

de.gsi.math.filter.iir.Cascade

de.gsi.math.filter.iir.Butterworth

public class Butterworth
extends Cascade

User facing class which contains all the methods the user uses to create Butterworth filters. This done in this way: Butterworth butterworth = new Butterworth(); Then call one of the methods below to create low-,high-,band-, or stopband filters. For example: butterworth.bandPass(2,250,50,5);

Constructor Summary

Constructors

Constructor and Description
Butterworth()

Method Summary

Modifier and Type	Method and Description
void	bandPass(int order, double sampleRate, double centerFrequency, double widthFrequency) Band-pass filter with default topology
void	bandPass(int order, double sampleRate, double centerFrequency, double widthFrequency, int directFormType) Band-pass filter with custom topology
void	bandStop(int order, double sampleRate, double centerFrequency, double widthFrequency) Band-stop filter with default topology
void	bandStop(int order, double sampleRate, double centerFrequency, double widthFrequency, int directFormType) Band-stop filter with custom topology
void	highPass(int order, double sampleRate, double cutoffFrequency) High-pass filter with default filter topology
void	highPass(int order, double sampleRate, double cutoffFrequency, int directFormType) High-pass filter with custom topology
void	lowPass(int order, double sampleRate, double cutoffFrequency) Butterworth Low-pass filter with default topology
void	lowPass(int order, double sampleRate, double cutoffFrequency, int directFormType) Butterworth Low-pass filter with custom topology

Methods inherited from class de.gsi.math.filter.iir.Cascade

applyScale, filter, getBiquad, getNumBiquads, reset, response, setLayout

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Butterworth

public Butterworth()

Method Detail

bandPass

public void bandPass(int order,
                     double sampleRate,
                     double centerFrequency,
                     double widthFrequency)

Band-pass filter with default topology

Parameters:

order - filter order (actual order is twice)

sampleRate - sampling rate of the system

centerFrequency - centre frequency

widthFrequency - width of the notch

bandPass

public void bandPass(int order,
                     double sampleRate,
                     double centerFrequency,
                     double widthFrequency,
                     int directFormType)

Band-pass filter with custom topology

Parameters:

order - filter order (actual order is twice)

sampleRate - sampling rate of the system

centerFrequency - centre frequency

widthFrequency - width of the notch

directFormType - filter topology

bandStop

public void bandStop(int order,
                     double sampleRate,
                     double centerFrequency,
                     double widthFrequency)

Band-stop filter with default topology

Parameters:

order - filter order (actual order is twice)

sampleRate - sampling rate of the system

centerFrequency - centre frequency

widthFrequency - width of the notch

bandStop

public void bandStop(int order,
                     double sampleRate,
                     double centerFrequency,
                     double widthFrequency,
                     int directFormType)

Band-stop filter with custom topology

Parameters:

order - filter order (actual order is twice)

sampleRate - sampling rate of the system

centerFrequency - centre frequency

widthFrequency - width of the notch

directFormType - filter topology

highPass

public void highPass(int order,
                     double sampleRate,
                     double cutoffFrequency)

High-pass filter with default filter topology

Parameters:

order - filter order (ideally only even orders)

sampleRate - sampling rate of the system

cutoffFrequency - cutoff of the system

highPass

public void highPass(int order,
                     double sampleRate,
                     double cutoffFrequency,
                     int directFormType)

High-pass filter with custom topology

Parameters:

order - filter order (ideally only even orders)

sampleRate - sSampling rate of the system

cutoffFrequency - cutoff of the system

directFormType - filter topology. See DirectFormAbstract.

lowPass

public void lowPass(int order,
                    double sampleRate,
                    double cutoffFrequency)

Butterworth Low-pass filter with default topology

Parameters:

order - the order of the filter

sampleRate - sampling rate of the system

cutoffFrequency - cutoff frequency

lowPass

public void lowPass(int order,
                    double sampleRate,
                    double cutoffFrequency,
                    int directFormType)

Butterworth Low-pass filter with custom topology

Parameters:

order - the order of the filter

sampleRate - sampling rate of the system

cutoffFrequency - cutoff frequency

directFormType - filter topology. This is either DirectFormAbstract.DIRECT_FORM_I or DIRECT_FORM_II