xal.tools.dsp

Class ExpFilter

java.lang.Object

xal.tools.dsp.ExpFilter

public class ExpFilter
extends java.lang.Object

Discrete filter based upon the FourierExpTransform class.

When the filters are described as "perfect", we are implying that they do not roll off with frequency (thus, they are of infinite order). The transfer function of the filter has values of either unity or zero. This may or may not correspond to a linear phase filter.

See Also:

gov.sns.tools.dsp.FourierExpTransform

Constructor Summary

Constructors

Constructor and Description
ExpFilter(int szData) Create a new filter object for processing discrete functions (i.e., objects of type double[]) with the given size.

Method Summary

Modifier and Type	Method and Description
int	getDataSize() Return the expected size of the discrete function to be processed.
int	getMaximumFrequency() Return the maximum discrete frequency processed by this filter.
double[]	parabolicLowPass(int intFreq, double[] arrFunc) Parabolic low-pass filter.
double[]	perfectBandPass(int intFreqLow, int intFreqHigh, double[] arrFunc) Perfect band-pass filter.
double[]	perfectHighPass(int intFreq, double[] arrFunc) Perfect high-pass filter.
double[]	perfectLowPass(int intFreq, double[] arrFunc) Perfect low-pass filter.
double[]	perfectNotch(int intFreq, double[] arrFunc) Perfect notch filter.
double[]	perfectNotch(int intFreqLow, int intFreqHigh, double[] arrFunc) Perfect notch filter.

Methods inherited from class java.lang.Object

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

Constructor Detail

ExpFilter

public ExpFilter(int szData)

Create a new filter object for processing discrete functions (i.e., objects of type double[]) with the given size.

Parameters:

szData - size of the functions this filter can process

Method Detail

getDataSize

public int getDataSize()

Return the expected size of the discrete function to be processed.

Returns:

array size for functions this filter object can process

getMaximumFrequency

public int getMaximumFrequency()

Return the maximum discrete frequency processed by this filter.

Returns:

maximum (positive) filter frequency

perfectLowPass

public double[] perfectLowPass(int intFreq,
                               double[] arrFunc)
                        throws java.lang.IndexOutOfBoundsException,
                               java.lang.IllegalArgumentException

Perfect low-pass filter. Any frequency components greater than the given (discrete) cut off frequency are complete removed. The filtered function is returned.

Parameters:

intFreq - discrete cut off frequency

arrFunc - discrete function to be filtered

Returns:

filtered discrete function

Throws:

java.lang.IndexOutOfBoundsException - cut off frequency either negative or greater than max frequency

java.lang.IllegalArgumentException - discrete function size is not equal to filter dimensions

perfectHighPass

public double[] perfectHighPass(int intFreq,
                                double[] arrFunc)
                         throws java.lang.IndexOutOfBoundsException,
                                java.lang.IllegalArgumentException

Perfect high-pass filter. Any frequency components less than the given (discrete) cut off frequency are complete removed. The filtered function is returned.

Parameters:

intFreq - discrete cut off frequency

arrFunc - discrete function to be filtered

Returns:

filtered discrete function

Throws:

java.lang.IndexOutOfBoundsException - cut off frequency either negative or greater than max frequency

java.lang.IllegalArgumentException - discrete function size is not equal to filter dimensions

perfectBandPass

public double[] perfectBandPass(int intFreqLow,
                                int intFreqHigh,
                                double[] arrFunc)
                         throws java.lang.IndexOutOfBoundsException,
                                java.lang.IllegalArgumentException

Perfect band-pass filter. Any frequency components outside the the given (discrete) cut off frequencies (exclusive) are complete removed. That is, only discrete frequency components inside the interval [intFreqLow,intFreqHigh] are contained in the returned function.

Parameters:

intFreqLow - discrete low-band cut off frequency

intFreqHigh - discrete high-band cut off frequency

arrFunc - discrete function to be filtered

Returns:

filtered discrete function

Throws:

java.lang.IndexOutOfBoundsException - cut off frequency either negative or greater than data size

java.lang.IllegalArgumentException - discrete function size is not equal to filter dimensions

perfectNotch

public double[] perfectNotch(int intFreqLow,
                             int intFreqHigh,
                             double[] arrFunc)
                      throws java.lang.IndexOutOfBoundsException,
                             java.lang.IllegalArgumentException

Perfect notch filter. Any frequency components inside the the given (discrete) cut off frequencies (inclusive) are complete removed. That is, only discrete frequency components outside the interval [intFreqLow,intFreqHigh] are contained in the returned function.

Parameters:

intFreqLow - discrete low-band cut off frequency

intFreqHigh - discrete high-band cut off frequency

arrFunc - discrete function to be filtered

Returns:

filtered discrete function

Throws:

java.lang.IndexOutOfBoundsException - cut off frequency either negative or greater than data size

java.lang.IllegalArgumentException - discrete function size is not equal to filter dimensions

perfectNotch

public double[] perfectNotch(int intFreq,
                             double[] arrFunc)
                      throws java.lang.IndexOutOfBoundsException,
                             java.lang.IllegalArgumentException

Perfect notch filter. Removes a single (discrete) frequency component from the given function.

Parameters:

intFreq - discrete frequency to be removed

arrFunc - discrete function to be filtered

Returns:

filtered discrete function

Throws:

java.lang.IndexOutOfBoundsException - cut off frequency either negative or greater than data size

java.lang.IllegalArgumentException - discrete function size is not equal to filter dimensions

parabolicLowPass

public double[] parabolicLowPass(int intFreq,
                                 double[] arrFunc)
                          throws java.lang.IndexOutOfBoundsException,
                                 java.lang.IllegalArgumentException

Parabolic low-pass filter. Any frequency components greater than the given (discrete) cut off frequency are complete removed. Frequencies in the pass-band are attenuated by a transfer function with unit high and parabolic shape with value zero at the cut off frequency.

Parameters:

intFreq - discrete cut off frequency

arrFunc - discrete function to be filtered

Returns:

filtered discrete function

Throws:

java.lang.IndexOutOfBoundsException - cut off frequency either negative or greater than max frequency

java.lang.IllegalArgumentException - discrete function size is not equal to filter dimensions