triana.types.util

Class SigAnalWindows

java.lang.Object

triana.types.util.SigAnalWindows

public class SigAnalWindows
extends java.lang.Object

Class to provide utility methods for applying windowing functions in the context of signal analysis. Used by units in more than one toolbox. Static methods allow these functions to be applied to time-domain or frequency-domain data. The frequency-domain methods allow one to apply only the right-half or left-half window so that windowing can be correctly applied to spectra stored according to the Triana storage model. If rounding of narrow bandwidths is desired this will be done automatically if the input spectrum is narrow-band, but not if it is padded with zeros. There are methods also for providing a list of available window functions to units to use in drop-downs in parameter windows. <\p>

So far there are 6 defined window functions: Bartlett, Blackman, Gaussian, Hamming, Hanning, Welch. Further functions can be added by writing three methods for each window.

Constructor Summary

Constructors

Constructor and Description
SigAnalWindows()

Method Summary

Methods

Modifier and Type	Method and Description
static GraphType	applyWindowFunction(GraphType input, java.lang.String function, boolean allocMem) Method to apply a window function to an input data set on the assumption that the data are stored as a simple sequential set.
static void	applyWindowToSpectral(double[] input, java.lang.String function, double low, boolean twoSided, boolean narrow) Method to apply a window function to an input double[] array that is stored using the Triana model for Spectral data sets.
static double[]	Bartlett(int points) Create a Bartlett window spanning the given number of points.
static double	Bessel0(double x)
static double[]	Blackman(int points) Create a Blackman window spanning the given number of points.
static double[]	BlackmanHarris92(int points) Create a Blackman-Harris 92dB window spanning the given number of points.
static void	doFullWindow(java.lang.String function, double[] input, int from, int to) Selects the correct window and applies its full width to the input array between the two given indices.
static void	doHalfWindow(java.lang.String function, double[] input, int from, int to, boolean right) Selects the given window and applies half of its width to the input array between the two given indices.
static double[]	FTHP(int points) Create a FTHP window spanning the given number of points.
static double[]	FTNI(int points) Create a FTNI window spanning the given number of points.
static double[]	FTSRS(int points) Create a FTSRS window spanning the given number of points.
static double[]	Gaussian(int points) Create a Gaussian window spanning the given number of points.
static double[]	Hamming(int points) Create a Hamming window spanning the given number of points.
static double[]	Hann(int points) Create a Hann window spanning the given number of points.
static double[]	HFT70(int points) Create a HFT70 window spanning the given number of points.
static double[]	HFT95(int points) Create a HFT95 window spanning the given number of points.
static double[]	Kaiser(int points, double alpha) Create a Kaiser window spanning the given number of points and depending on the given parameter alpha.
static double[]	Kaiser3(int points) Create a Kaiser3 window spanning the given number of points (with parameter alpha = 3).
static double[]	Kaiser4(int points) Create a Kaiser4 window spanning the given number of points (with parameter alpha = 4).
static double[]	Kaiser5(int points) Create a Kaiser5 window spanning the given number of points (with parameter alpha = 5).
static double[]	Kaiser6(int points) Create a Kaiser6 window spanning the given number of points (with parameter alpha = 6).
static double[]	Kaiser7(int points) Create a Kaiser7 window spanning the given number of points (with parameter alpha = 7).
static java.lang.String	listOfWindows() Returns the list of windows available.
static java.lang.String[]	listOfWindowsAsArray()
static double[]	Nuttall3(int points) Create a Nuttall3 window spanning the given number of points.
static double[]	Nuttall3a(int points) Create a Nuttall3a window spanning the given number of points.
static double[]	Nuttall3b(int points) Create a Nuttall3b window spanning the given number of points.
static double[]	Nuttall4(int points) Create a Nuttall4 window spanning the given number of points.
static double[]	Rectangle(int points) Create a Rectangle window spanning the given number of points.
static double[]	SFT3F(int points) Create a SFT3F window spanning the given number of points.
static double[]	SFT3M(int points) Create a SFT3M window spanning the given number of points.
static double[]	SFT4F(int points) Create a SFT4F window spanning the given number of points.
static double[]	SFT4M(int points) Create a SFT4M window spanning the given number of points.
static double[]	SFT5F(int points) Create a SFT5F window spanning the given number of points.
static double[]	SFT5M(int points) Create a SFT5M window spanning the given number of points.
static double[]	Welch(int points) Create a Welch window spanning the given number of points.

Methods inherited from class java.lang.Object

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

Constructor Detail

SigAnalWindows

public SigAnalWindows()

Method Detail

applyWindowFunction

public static GraphType applyWindowFunction(GraphType input,
                            java.lang.String function,
                            boolean allocMem)

Method to apply a window function to an input data set on the assumption that the data are stored as a simple sequential set. This is true for time-domain data but not for spectral data, whose storage model is more complicated. For spectral data use the method applyWindowToSpectral<\i>. Input data must be VectorType or TimeFrequency. If another GraphType is input, then it will be output unchanged. (Note: no error flag is returned.)

Parameters:

input - Must be either of type VectorType or TimeFrequency

function - The keyword naming the window function to be applied

allocMem - True<\i> if output is to be a copy of input, false if input is overwritten

Returns:

The windowed data, of the same type as the input

applyWindowToSpectral

public static void applyWindowToSpectral(double[] input,
                         java.lang.String function,
                         double low,
                         boolean twoSided,
                         boolean narrow)

Method to apply a window function to an input double[] array that is stored using the Triana model for Spectral data sets. For non-spectral data use the method applyWindowFunction<\i>. The method does not return any values; it simply modifies the input data.

Parameters:

input - Should be stored in the way that Spectra are stored in Triana

function - The keyword naming the window function to be applied

low - The lower frequency bound (only tested to see if it is non-zero if narrow band)

twoSided - True<\i> if the data are stored in a two-sided way

narrow - True<\i> if the data are narrow-band

listOfWindows

public static java.lang.String listOfWindows()

Returns the list of windows available. Update this if you change the window functions. The output of this is used by setGUIInformation() below and can be called by other units that use the static methods of this unit and want to offer the up-to-date list of windows in their own parameter window.

Returns:

String list of available windows

listOfWindowsAsArray

public static java.lang.String[] listOfWindowsAsArray()

Returns:

a copy of the string array of all possible window function names.

doFullWindow

public static void doFullWindow(java.lang.String function,
                double[] input,
                int from,
                int to)

Selects the correct window and applies its full width to the input array between the two given indices. Data inside the range of the window (between the given indices) are multiplied by the appropriate window function. Data outside the window are not affected.

The method can be extended to any window function by providing a method with the name of the window and one int argument, which returns the window values in a double[] array of length equal to the argument.

Parameters:

function - The name of the window to be applied

input - The data set to be multiplied by the window

from - The index in the input data set where the window starts

to - The index in the input data set where the window terminates

doHalfWindow

public static void doHalfWindow(java.lang.String function,
                double[] input,
                int from,
                int to,
                boolean right)

Selects the given window and applies half of its width to the input array between the two given indices. The value of the boolean argument determines which half: if true it is the right half of the window and if false the left half. Data inside the range of the window (between the given indices) are multiplied by the appropriate window function. Data outside the window are not affected.

This method allows correct treatment of spectra, where the negative and positive frequencies are not stored in a way that is continuous across zero frequency, so the window needs to be split and applied to different regions of the stored spectrum.

The method can be extended to any window function by providing a method with the name of the window and one int argument, which returns the window values in a double[] array of length equal to the argument.

Parameters:

function - The name of the window to be applied

input - The data set to be multiplied by the window

from - The index in the input data set where the window starts

to - The index in the input data set where the window terminates

Hann

public static double[] Hann(int points)

Create a Hann window spanning the given number of points. This window is also known as a Hanning window.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

Bartlett

public static double[] Bartlett(int points)

Create a Bartlett window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

Welch

public static double[] Welch(int points)

Create a Welch window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

Hamming

public static double[] Hamming(int points)

Create a Hamming window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

Gaussian

public static double[] Gaussian(int points)

Create a Gaussian window spanning the given number of points. Its domain is fixed by the place where it falls to exp(-4.5) = 0.0111.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

Blackman

public static double[] Blackman(int points)

Create a Blackman window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

Rectangle

public static double[] Rectangle(int points)

Create a Rectangle window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

BlackmanHarris92

public static double[] BlackmanHarris92(int points)

Create a Blackman-Harris 92dB window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

Nuttall3

public static double[] Nuttall3(int points)

Create a Nuttall3 window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

Nuttall3a

public static double[] Nuttall3a(int points)

Create a Nuttall3a window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

Nuttall3b

public static double[] Nuttall3b(int points)

Create a Nuttall3b window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

Nuttall4

public static double[] Nuttall4(int points)

Create a Nuttall4 window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

Kaiser

public static double[] Kaiser(int points,
              double alpha)

Create a Kaiser window spanning the given number of points and depending on the given parameter alpha.

Parameters:

points - The number of points that span the full size of the window

alpha - The standard parameter of the Kaiser family

Returns:

The window values

Bessel0

public static double Bessel0(double x)

Kaiser3

public static double[] Kaiser3(int points)

Create a Kaiser3 window spanning the given number of points (with parameter alpha = 3).

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

Kaiser4

public static double[] Kaiser4(int points)

Create a Kaiser4 window spanning the given number of points (with parameter alpha = 4).

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

Kaiser5

public static double[] Kaiser5(int points)

Create a Kaiser5 window spanning the given number of points (with parameter alpha = 5).

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

Kaiser6

public static double[] Kaiser6(int points)

Create a Kaiser6 window spanning the given number of points (with parameter alpha = 6).

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

Kaiser7

public static double[] Kaiser7(int points)

Create a Kaiser7 window spanning the given number of points (with parameter alpha = 7).

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

SFT3F

public static double[] SFT3F(int points)

Create a SFT3F window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

SFT4F

public static double[] SFT4F(int points)

Create a SFT4F window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

SFT5F

public static double[] SFT5F(int points)

Create a SFT5F window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

SFT3M

public static double[] SFT3M(int points)

Create a SFT3M window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

SFT4M

public static double[] SFT4M(int points)

Create a SFT4M window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

SFT5M

public static double[] SFT5M(int points)

Create a SFT5M window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

FTNI

public static double[] FTNI(int points)

Create a FTNI window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

FTHP

public static double[] FTHP(int points)

Create a FTHP window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

FTSRS

public static double[] FTSRS(int points)

Create a FTSRS window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

HFT70

public static double[] HFT70(int points)

Create a HFT70 window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values

HFT95

public static double[] HFT95(int points)

Create a HFT95 window spanning the given number of points.

Parameters:

points - The number of points that span the full size of the window

Returns:

The window values