ptolemy.domains.continuous.lib
Class BandlimitedNoise
java.lang.Object
ptolemy.kernel.util.NamedObj
ptolemy.kernel.InstantiableNamedObj
ptolemy.kernel.Entity
ptolemy.kernel.ComponentEntity
ptolemy.actor.AtomicActor
ptolemy.actor.TypedAtomicActor
ptolemy.actor.lib.Source
ptolemy.actor.lib.RandomSource
ptolemy.actor.lib.Gaussian
ptolemy.domains.continuous.lib.BandlimitedNoise
- All Implemented Interfaces:
- java.io.Serializable, java.lang.Cloneable, Actor, Executable, FiringsRecordable, Initializable, TypedActor, Changeable, Debuggable, DebugListener, Derivable, Instantiable, ModelErrorHandler, MoMLExportable, Moveable, Nameable
public class BandlimitedNoise
- extends Gaussian
This actor generates continuous-time noise with a Gaussian distribution
and controlled bandwidth. The power spectrum of the noise produced
is given by
S(f) = T s^2 sinc^4(pi f T)
where f is frequency, s is the standard deviation,
and the sinc function is given by
sinc(a) = sin(a)/a
Here, T = 1/b, where b is the value of the bandwidth parameter.
Notice that the power declines as the fourth power
of one over the frequency. The bandwidth parameter specifies
the frequency (in Hertz) at which the first zero occurs, or,
equivalently, roughly the width of the main lobe.
This actor may affect the step size taken by the solver. Specifically,
it ensures that the solver provides executions at least as frequently
as twice the specified bandwidth. This is nominally the Nyquist frequency
of an ideally bandlimited noise frequency, but since this noise process
is not ideally bandlimited, the solver samples will typically have
aliasing distortion. If you need to control that aliasing distortion,
then you can set the maxStepSize parameter to something smaller
than 1/2b, where c is the bandwidth.
For some uses, the effect that this actor has on the step size may
be undesirable because it increases the cost of simulation.
If a less rigorous form of noise is desired (for rough models or
simple demonstrations), you can use the Noise actor.
- Since:
- Ptolemy II 8.0
- Version:
- $Id: BandlimitedNoise.java 57046 2010-01-27 23:35:53Z cxh $
- Author:
- Edward A. Lee
- See Also:
- Serialized Form
- Accepted Rating:
- Proposed Rating:
|
Field Summary |
private Time |
_timeOfValueAtEnd
Time associated with the second random number of the current interval. |
private Time |
_timeOfValueAtStart
Time associated with the first random number of the current interval. |
private double |
_valueAtEnd
The random number at the end of the end of the current interval. |
private double |
_valueAtStart
The random number at the start of the current interval. |
Parameter |
bandwidth
The bandwidth of the noise random process in Hertz. |
| Fields inherited from class ptolemy.kernel.util.NamedObj |
_changeListeners, _changeLock, _changeRequests, _debugging, _debugListeners, _elementName, _isPersistent, _verbose, _workspace, ATTRIBUTES, CLASSNAME, COMPLETE, CONTENTS, DEEP, FULLNAME, LINKS |
|
Method Summary |
protected double |
_generateGaussian()
Generate a new random number. |
protected void |
_generateRandomNumber()
Generate a new random number. |
void |
fire()
Produce a number that is linearly interpolated within the
current integration step, if linearlyInterpolate is true, or
the random number for the beginning of the integration
step otherwise. |
void |
initialize()
Initialize the random number generator with the seed, if it
has been given. |
boolean |
postfire()
If we are at the end of the current interval, then generate
a new random number for the new interval, and request a
refiring at the end of that interval. |
| Methods inherited from class ptolemy.actor.AtomicActor |
_actorFiring, _actorFiring, addActorFiringListener, addInitializable, connectionsChanged, createReceivers, declareDelayDependency, getCausalityInterface, getDirector, getExecutiveDirector, getManager, inputPortList, isFireFunctional, isStrict, iterate, newReceiver, outputPortList, preinitialize, pruneDependencies, recordFiring, removeActorFiringListener, removeDependency, removeInitializable, setContainer, stop, stopFire, terminate, wrapup |
| Methods inherited from class ptolemy.kernel.ComponentEntity |
_adjustDeferrals, _checkContainer, _getContainedObject, _propagateExistence, getContainer, instantiate, isAtomic, isOpaque, moveDown, moveToFirst, moveToIndex, moveToLast, moveUp, propagateExistence, setName |
| Methods inherited from class ptolemy.kernel.Entity |
_description, _exportMoMLContents, _removePort, _validateSettables, connectedPortList, connectedPorts, containedObjectsIterator, getAttribute, getPort, getPorts, linkedRelationList, linkedRelations, portList, removeAllPorts, setClassDefinition, uniqueName |
| Methods inherited from class ptolemy.kernel.util.NamedObj |
_addAttribute, _adjustOverride, _attachText, _cloneFixAttributeFields, _debug, _debug, _debug, _debug, _debug, _getIndentPrefix, _isMoMLSuppressed, _markContentsDerived, _propagateValue, _recordDecoratedAttributes, _removeAttribute, _splitName, _stripNumericSuffix, addChangeListener, addDebugListener, attributeList, attributeList, 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, propagateValue, propagateValues, removeChangeListener, removeDebugListener, requestChange, setClassName, setDeferringChangeRequests, setDerivedLevel, setDisplayName, setModelErrorHandler, setPersistent, setSource, sortContainedObjects, toplevel, toString, validateSettables, workspace |
| Methods inherited from class java.lang.Object |
equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
bandwidth
public Parameter bandwidth
- The bandwidth of the noise random process in Hertz.
The bandwidth is the frequency where the power spectral
density first hits zero. This is a double that defaults to
10.0 Hertz.
_timeOfValueAtEnd
private Time _timeOfValueAtEnd
- Time associated with the second random number of the current interval.
_timeOfValueAtStart
private Time _timeOfValueAtStart
- Time associated with the first random number of the current interval.
_valueAtStart
private double _valueAtStart
- The random number at the start of the current interval.
_valueAtEnd
private double _valueAtEnd
- The random number at the end of the end of the current interval.
BandlimitedNoise
public BandlimitedNoise(CompositeEntity container,
java.lang.String name)
throws NameDuplicationException,
IllegalActionException
- Construct an actor with the given container and name.
- Parameters:
container - The container.name - The name of this actor.
- Throws:
IllegalActionException - If the actor cannot be contained
by the proposed container.
NameDuplicationException - If the container already has an
actor with this name.
fire
public void fire()
throws IllegalActionException
- Produce a number that is linearly interpolated within the
current integration step, if linearlyInterpolate is true, or
the random number for the beginning of the integration
step otherwise.
- Specified by:
fire in interface Executable- Overrides:
fire in class Gaussian
- Throws:
IllegalActionException - If the superclass throws it.
initialize
public void initialize()
throws IllegalActionException
- Initialize the random number generator with the seed, if it
has been given. A seed of zero is interpreted to mean that no
seed is specified. In such cases, a seed based on the current
time and this instance of a RandomSource is used to be fairly
sure that two identical sequences will not be returned.
- Specified by:
initialize in interface Initializable- Overrides:
initialize in class RandomSource
- Throws:
IllegalActionException - If the parent class throws it.
postfire
public boolean postfire()
throws IllegalActionException
- If we are at the end of the current interval, then generate
a new random number for the new interval, and request a
refiring at the end of that interval.
- Specified by:
postfire in interface Executable- Overrides:
postfire in class RandomSource
- Returns:
- True if it is OK to continue.
- Throws:
IllegalActionException - If the base class throws it.
_generateGaussian
protected double _generateGaussian()
throws IllegalActionException
- Generate a new random number.
- Returns:
- A random number.
- Throws:
IllegalActionException - If parameter values are incorrect.
_generateRandomNumber
protected void _generateRandomNumber()
throws IllegalActionException
- Generate a new random number. This gets called in initialize()
and in the first fire() method of an iteration. It produces a number
that is to be the random number at the end of the current
iteration.
- Overrides:
_generateRandomNumber in class Gaussian
- Throws:
IllegalActionException - If parameter values are incorrect.