signalproc.algorithms

Class FFT

java.lang.Object

org.trianacode.taskgraph.Unit

signalproc.algorithms.FFT

public class FFT
extends Unit

A FFT unit to perform a Fast Fourier Transform on the input data.

If the input implements the Signal Interface, then signal parameters (sampling rate, etc) are used to produce a correctly normalized spectrum, ie an approximation to the continuous FT. If the input data are real, then the output are one-sided. The output is a ComplexSpectrum data type.

If the input data implements Spectral, then an inverse FFT is performed. If the data are one-sided, the the output is a SampleSet. If the data are two-sided, then the output is a ComplexSampleSet. If the data are narrow-band, they are converted to full bandwidth (padding with zeroes) before the inverse transform is applied. In each case, the normalization is based on the data in the Spectral data set.

If the input data does not implement the Spectral or Signal Interfaces, then it is assumed to require a direct (forward) FFT, and the output is a ComplexSpectrum data set with no normalization applied. This is the same as for an input SampleSet with sampling frequency = 1.

If this automatic behavior is not desired, then use the Units DirectFFT and InverseFFT instead. These Units always perform the FFT in the indicated direction and apply no normalization, not even the 1/N. Their output is always a VectorType (real or complex as appropriate) and the data are always two-sided.

If the input data are not uniformly sampled, then an error is generated and no output takes place.

The FFT is performed using the FFTC algorithm.

See Also:

FFTC, Spectral, Signal, ComplexSpectrum, Spectrum, SampleSet, ComplexSampleSet

Field Summary

Fields inherited from class org.trianacode.taskgraph.Unit

CLONE_ALL_OUTPUT, CLONE_MULTIPLE_OUTPUT, COPY_OUTPUT, ESSENTIAL, ESSENTIAL_IF_CONNECTED, IMMEDIATE_UPDATE, INTERNAL, LATE_INITIALIZE, NO_UPDATE, ON_TASK_INSTANTATION, ON_USER_ACCESS, OPTIONAL, PROCESS_UPDATE, TRANSIENT, TRANSIENT_ACCESSIBLE, USER_ACCESSIBLE

Constructor Summary

Constructors

Constructor and Description
FFT()

Method Summary

Methods

Modifier and Type	Method and Description
java.lang.String	getHelpFile()
java.lang.String[]	getInputTypes() This method should return an array of the data types accepted by nodes not specified in getNodeInputTypes (e.g.
java.lang.String[]	getOutputTypes() This method should return an array of the data types output by nodes not specified in getNodeOutputTypes() (e.g.
java.lang.String	getPopUpDescription() This returns a brief! description of what the unit does.
void	init() Initialses information specific to FFT.
void	parameterUpdate(java.lang.String name, java.lang.Object value) Used to set each of FFT's parameters.
void	process() ********************************************* ** A Java FFT algorithm *** *********************************************
void	reset() Called when the reset button is pressed within the MainTriana Window
void	stopping() Called when the stop button is pressed within the MainTriana Window

Methods inherited from class org.trianacode.taskgraph.Unit

debug, debug, defineParameter, dispose, extractClipInState, getClipIn, getClipIn, getControlInterface, getDefaultInputNodes, getDefaultNodeRequirement, getDefaultOutputNodes, getDisplayName, getDisplayPackage, getGUIBuilderV2Info, getHelpFileLocation, getInputAtNode, getInputNodeCount, getMaximumInputNodes, getMaximumOutputNodes, getMinimumInputNodes, getMinimumOutputNodes, getNodeInputTypes, getNodeOutputTypes, getOutputNodeCount, getOutputPolicy, getPackageName, getParameter, getParameterPanelClass, getParameterPanelInstantiate, getParameterType, getParameterUpdatePolicy, getRunnableInterface, getTask, getTaskGraphContext, getToolName, getToolPackage, getToolTable, getVersion, hideParameterPanel, isClipInName, isInputAtNode, isOutputSent, isParameter, log, log, notifyError, notifyError, output, outputAtNode, outputAtNode, parameterUpdated, putClipIn, removeClipIn, removeParameter, restoreClipInState, setDefaultInputNodes, setDefaultNodeRequirement, setDefaultOutputNodes, setDisplayName, setDisplayPackage, setGUIBuilderV2Info, setHelpFileLocation, setMaximumInputNodes, setMaximumOutputNodes, setMinimumInputNodes, setMinimumOutputNodes, setOutputPolicy, setParameter, setParameterPanelClass, setParameterPanelInstantiate, setParameterUpdatePolicy, setPopUpDescription, setRunnableInterface, setToolName, setToolPackage, setVersion, showParameterPanel

Methods inherited from class java.lang.Object

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

Constructor Detail

FFT

public FFT()

Method Detail

process

public void process()
             throws java.lang.Exception

********************************************* ** A Java FFT algorithm *** *********************************************

Specified by:

process in class Unit

Throws:

java.lang.Exception

init

public void init()

Initialses information specific to FFT.

Overrides:

init in class Unit

reset

public void reset()

Called when the reset button is pressed within the MainTriana Window

Overrides:

reset in class Unit

stopping

public void stopping()

Called when the stop button is pressed within the MainTriana Window

Overrides:

stopping in class Unit

parameterUpdate

public void parameterUpdate(java.lang.String name,
                   java.lang.Object value)

Used to set each of FFT's parameters.

Overrides:

parameterUpdate in class Unit

getInputTypes

public java.lang.String[] getInputTypes()

Description copied from class: Unit

This method should return an array of the data types accepted by nodes not specified in getNodeInputTypes (e.g. triana.types.VectorType). If no package is specified then triana.types is assumed.

Specified by:

getInputTypes in class Unit

Returns:

a string containing the names of the types allowed to be input to FFT, each separated by a white space.

getOutputTypes

public java.lang.String[] getOutputTypes()

Description copied from class: Unit

This method should return an array of the data types output by nodes not specified in getNodeOutputTypes() (e.g. triana.types.VectorType). If no package is specified then triana.types is assumed.

Specified by:

getOutputTypes in class Unit

Returns:

an array of the output types for this unit

getPopUpDescription

public java.lang.String getPopUpDescription()

This returns a brief! description of what the unit does. The text here is shown in a pop up window when the user puts the mouse over the unit icon for more than a second.

Overrides:

getPopUpDescription in class Unit

getHelpFile

public java.lang.String getHelpFile()