public class FIR extends SDFTransformer
Note that the current implementation of this actor only reads its parameters during initialization, so the filter cannot be changed during execution.
When the decimation (interpolation) parameters are different from unity, the filter behaves exactly as it were followed (preceded) by a DownSample (UpSample) actor. However, the implementation is much more efficient than it would be using UpSample or DownSample actors; a polyphase structure is used internally, avoiding unnecessary use of memory and unnecessary multiplication by zero. Arbitrary sample-rate conversions by rational factors can be accomplished this way.
To design a filter for a multirate system, simply assume the sample rate is the product of the interpolation parameter and the input sample rate, or equivalently, the product of the decimation parameter and the output sample rate. In particular, considerable care must be taken to avoid aliasing. Specifically, if the input sample rate is f, then the filter stopband should begin before f/2. If the interpolation ratio is i, then f/2 is a fraction 1/2i of the sample rate at which you must design your filter.
The decimationPhase parameter is somewhat subtle. It is exactly equivalent the phase parameter of the DownSample actor. Its interpretation is as follows; when decimating, samples are conceptually discarded (although a polyphase structure does not actually compute the discarded samples). If you are decimating by a factor of three, then you will select one of every three outputs, with three possible phases. When decimationPhase is zero (the default), the latest (most recent) samples are the ones selected. The decimationPhase must be strictly less than the decimation ratio.
Note: in this description "sample rate" refers to the physical sampling rate of an A/D converter in the system. In other words, the number of data samples per second. This is not usually specified anywhere in an SDF system, and most definitely does NOT correspond to the SDF rate parameters of this actor. This actor automatically sets the rates of the input and output ports to the decimation and interpolation ratios, respectively.
For more information about polyphase filters, see F. J. Harris, "Multirate FIR Filters for Interpolating and Desampling", in Handbook of Digital Signal Processing, Academic Press, 1987.
TokenEntity.ContainedObjectsIterator| Modifier and Type | Field and Description |
|---|---|
protected Token[] |
_data
The delay line.
|
protected int |
_decimationPhaseValue
DecimationPhase value.
|
protected int |
_decimationValue
Decimation value.
|
protected int |
_interpolationValue
Interpolation value.
|
protected int |
_mostRecent
The index into the delay line of the most recent input.
|
protected int |
_phaseLength
The phaseLength is ceiling(length/interpolation), where
length is the number of taps.
|
protected boolean |
_reinitializeNeeded
Indicator that at least one attribute has been changed
since the last initialization.
|
protected Token[] |
_taps
Local cache of the tap values.
|
protected Token |
_zero
Local cache of the zero token.
|
Parameter |
decimation
The decimation ratio of the filter.
|
Parameter |
decimationPhase
The decimation phase of the filter.
|
Parameter |
interpolation
The interpolation ratio of the filter.
|
Parameter |
taps
The taps of the filter.
|
input, input_tokenConsumptionRate, output, output_tokenInitProduction, output_tokenProductionRate_typesValid_actorFiringListeners, _initializables, _notifyingActorFiring, _stopRequested_changeListeners, _changeLock, _changeRequests, _debugging, _debugListeners, _deferChangeRequests, _elementName, _isPersistent, _verbose, _workspace, ATTRIBUTES, CLASSNAME, COMPLETE, CONTENTS, DEEP, FULLNAME, LINKSCOMPLETED, NOT_READY, STOP_ITERATING| Constructor and Description |
|---|
FIR(CompositeEntity container,
java.lang.String name)
Construct an actor with the given container and name.
|
| Modifier and Type | Method and Description |
|---|---|
protected java.util.Set<Inequality> |
_customTypeConstraints()
Set the output to be ≥ the monotonic function of the input port type.
|
protected void |
_initializeTaps()
Initialize the taps.
|
protected void |
_reinitialize()
Reinitialize local variables in response to changes in attributes.
|
void |
attributeChanged(Attribute attribute)
Set a flag that causes recalculation of various local variables
that are used in execution on the next invocation of fire().
|
java.lang.Object |
clone(Workspace workspace)
Clone the actor into the specified workspace.
|
void |
fire()
Consume the inputs and produce the outputs of the FIR filter.
|
void |
initialize()
Perform domain-specific initialization by calling the
initialize(Actor) method of the director.
|
boolean |
prefire()
Return false if the input does not have enough tokens to fire.
|
_containedTypeConstraints, _defaultTypeConstraints, _fireAt, _fireAt, attributeTypeChanged, clone, isBackwardTypeInferenceEnabled, newPort, typeConstraintList, typeConstraints_actorFiring, _actorFiring, _declareDelayDependency, addActorFiringListener, addInitializable, connectionsChanged, createReceivers, declareDelayDependency, getCausalityInterface, getDirector, getExecutiveDirector, getManager, inputPortList, isFireFunctional, isStrict, iterate, newReceiver, outputPortList, postfire, preinitialize, pruneDependencies, recordFiring, removeActorFiringListener, removeDependency, removeInitializable, setContainer, stop, stopFire, terminate, wrapup_adjustDeferrals, _checkContainer, _getContainedObject, _propagateExistence, getContainer, instantiate, isAtomic, isOpaque, moveDown, moveToFirst, moveToIndex, moveToLast, moveUp, propagateExistence, setName_addPort, _description, _exportMoMLContents, _removePort, _validateSettables, connectedPortList, connectedPorts, containedObjectsIterator, getAttribute, getPort, getPorts, linkedRelationList, linkedRelations, portList, removeAllPorts, setClassDefinition, uniqueName_setParent, exportMoML, getChildren, getElementName, getParent, getPrototypeList, isClassDefinition, isWithinClassDefinition_addAttribute, _adjustOverride, _attachText, _cloneFixAttributeFields, _containedDecorators, _copyChangeRequestList, _debug, _debug, _debug, _debug, _debug, _executeChangeRequests, _getIndentPrefix, _isMoMLSuppressed, _markContentsDerived, _notifyHierarchyListenersAfterChange, _notifyHierarchyListenersBeforeChange, _propagateValue, _removeAttribute, _splitName, _stripNumericSuffix, addChangeListener, addDebugListener, addHierarchyListener, attributeDeleted, attributeList, attributeList, decorators, deepContains, depthInHierarchy, description, description, event, executeChangeRequests, exportMoML, exportMoML, exportMoML, exportMoML, exportMoMLPlain, getAttribute, getAttributes, getChangeListeners, getClassName, getDecoratorAttribute, getDecoratorAttributes, getDerivedLevel, getDerivedList, getDisplayName, getFullName, getModelErrorHandler, getName, getName, getSource, handleModelError, isDeferringChangeRequests, isOverridden, isPersistent, lazyContainedObjectsIterator, message, notifyOfNameChange, propagateValue, propagateValues, removeAttribute, removeChangeListener, removeDebugListener, removeHierarchyListener, requestChange, setClassName, setDeferringChangeRequests, setDerivedLevel, setDisplayName, setModelErrorHandler, setPersistent, setSource, sortContainedObjects, toplevel, toString, validateSettables, workspaceequals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, waitcreateReceivers, getCausalityInterface, getDirector, getExecutiveDirector, getManager, inputPortList, newReceiver, outputPortListisFireFunctional, isStrict, iterate, postfire, stop, stopFire, terminateaddInitializable, preinitialize, removeInitializable, wrapupdescription, getContainer, getDisplayName, getFullName, getName, getName, setNamegetDerivedLevel, getDerivedList, propagateValuepublic Parameter decimation
public Parameter decimationPhase
public Parameter interpolation
public Parameter taps
protected Token[] _data
protected int _mostRecent
protected int _phaseLength
protected int _decimationValue
protected int _interpolationValue
protected int _decimationPhaseValue
protected boolean _reinitializeNeeded
protected Token[] _taps
protected Token _zero
public FIR(CompositeEntity container, java.lang.String name) throws NameDuplicationException, IllegalActionException
container - The container.name - The name of this actor.IllegalActionException - If the actor cannot be contained
by the proposed container.NameDuplicationException - If the container already has an
actor with this name.public void attributeChanged(Attribute attribute) throws IllegalActionException
attributeChanged in class NamedObjattribute - The attribute that changed.IllegalActionException - If the attribute contains
an invalid value or if the super method throws it.public java.lang.Object clone(Workspace workspace) throws java.lang.CloneNotSupportedException
clone in class TypedAtomicActorworkspace - The workspace for the new object.java.lang.CloneNotSupportedException - If a derived class contains
an attribute that cannot be cloned.NamedObj.exportMoML(Writer, int, String),
NamedObj.setDeferringChangeRequests(boolean)public void fire()
throws IllegalActionException
fire in interface Executablefire in class AtomicActor<TypedIOPort>IllegalActionException - If parameter values are invalid,
or if there is no director, or if runtime type conflicts occur.public void initialize()
throws IllegalActionException
initialize in interface Initializableinitialize in class AtomicActor<TypedIOPort>IllegalActionException - If the superclass throws it.public boolean prefire()
throws IllegalActionException
prefire in interface Executableprefire in class SDFTransformerIllegalActionException - If the superclass throws it.protected java.util.Set<Inequality> _customTypeConstraints()
_customTypeConstraints in class TypedAtomicActorprotected void _initializeTaps()
throws IllegalActionException
IllegalActionException - If we can't get the token from
the parameter taps.protected void _reinitialize()
throws IllegalActionException
IllegalActionException - If there is a problem reinitializing.