Package xal.tools.dsp

Class ExpFilter

java.lang.Object
xal.tools.dsp.ExpFilter
public class ExpFilter extends 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.

Author:
Christopher K. Allen
See Also:

  • Constructor Summary

    Constructors
    Constructor
    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
    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 Details

    • 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 Details

    • 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 IndexOutOfBoundsException, 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:
      IndexOutOfBoundsException - cut off frequency either negative or greater than max frequency
      IllegalArgumentException - discrete function size is not equal to filter dimensions

    • perfectHighPass

      public double[] perfectHighPass(int intFreq, double[] arrFunc) throws IndexOutOfBoundsException, 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:
      IndexOutOfBoundsException - cut off frequency either negative or greater than max frequency
      IllegalArgumentException - discrete function size is not equal to filter dimensions

    • perfectBandPass

      public double[] perfectBandPass(int intFreqLow, int intFreqHigh, double[] arrFunc) throws IndexOutOfBoundsException, 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:
      IndexOutOfBoundsException - cut off frequency either negative or greater than data size
      IllegalArgumentException - discrete function size is not equal to filter dimensions

    • perfectNotch

      public double[] perfectNotch(int intFreqLow, int intFreqHigh, double[] arrFunc) throws IndexOutOfBoundsException, 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:
      IndexOutOfBoundsException - cut off frequency either negative or greater than data size
      IllegalArgumentException - discrete function size is not equal to filter dimensions

    • perfectNotch

      public double[] perfectNotch(int intFreq, double[] arrFunc) throws IndexOutOfBoundsException, 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:
      IndexOutOfBoundsException - cut off frequency either negative or greater than data size
      IllegalArgumentException - discrete function size is not equal to filter dimensions

    • parabolicLowPass

      public double[] parabolicLowPass(int intFreq, double[] arrFunc) throws IndexOutOfBoundsException, 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:
      IndexOutOfBoundsException - cut off frequency either negative or greater than max frequency
      IllegalArgumentException - discrete function size is not equal to filter dimensions