agi.foundation.communications.antennas

(agi.foundation.communications-2024r3.jar)

Class MinimumVarianceDistortionlessResponseBeamformer

java.lang.Object

agi.foundation.infrastructure.DefinitionalObject

agi.foundation.communications.antennas.PhasedArrayBeamformer

agi.foundation.communications.antennas.MinimumVarianceDistortionlessResponseBeamformer

All Implemented Interfaces:

ICloneWithContext, IEnumerateDependencies, IEquatableDefinition, IFreezable

public class MinimumVarianceDistortionlessResponseBeamformer
extends PhasedArrayBeamformer

A Minimum Variance Distortionless Response (MVDR) beamformer, also referred to as a Capon beam former. This performs adaptive beam forming in order to maximize gain in a desired direction while minimizing the gain in other directions.

For additional information see reference "Optimum Array Processing Part IV of Detection, Estimation, and Modulation Theory" Harry L. Van Trees, Pg. 439

Constructor Summary

Constructors

Modifier	Constructor and Description
	MinimumVarianceDistortionlessResponseBeamformer() Initializes a new instance.
	MinimumVarianceDistortionlessResponseBeamformer(double beamVariance) Initializes a new instance.
	MinimumVarianceDistortionlessResponseBeamformer(double beamVariance, DirectionsProvider beamDirectionsProvider) Initializes a new instance.
	MinimumVarianceDistortionlessResponseBeamformer(double beamVariance, DirectionsProvider beamDirectionsProvider, DirectionsProvider nullDirectionsProvider) Initializes a new instance.
protected	MinimumVarianceDistortionlessResponseBeamformer(MinimumVarianceDistortionlessResponseBeamformer existingInstance, CopyContext context) Initializes a new instance as a copy of an existing instance.

Method Summary

Modifier and Type	Method and Description
protected boolean	checkForSameDefinition(MinimumVarianceDistortionlessResponseBeamformer other) Checks to determine if another instance has the same definition as this instance and returns true if it does.
protected boolean	checkForSameDefinition(PhasedArrayBeamformer other) Checks to determine if another instance has the same definition as this instance and returns true if it does.
Object	clone(CopyContext context) Clones this object using the specified context.
protected int	computeCurrentDefinitionHashCode() Computes a hash code based on the current properties of this object.
void	enumerateDependencies(DependencyEnumerator enumerator) Enumerates the dependencies of this object by calling DependencyEnumerator#enumerate(T) for each object that this object directly depends upon.
DirectionsProvider	getBeamDirectionsProvider() Gets the DirectionsProvider for providing the beam directions.
double	getBeamVariance() Gets the beam variance.
BeamformerWeightsEvaluator	getBeamWeightsEvaluator(EvaluatorGroup group, ISignalSource inputSignal, Vector linkDirection, Axes antennaAxes, List<PhasedArrayElement> elementPattern) Gets a BeamformerWeightsEvaluator which when evaluated produces a ComplexMatrix of element weights.
DirectionsProvider	getNullDirectionsProvider() Gets the DirectionsProvider for providing the null directions.
void	setBeamDirectionsProvider(DirectionsProvider value) Sets the DirectionsProvider for providing the beam directions.
void	setBeamVariance(double value) Sets the beam variance.
void	setNullDirectionsProvider(DirectionsProvider value) Sets the DirectionsProvider for providing the null directions.

Methods inherited from class agi.foundation.communications.antennas.PhasedArrayBeamformer

checkForSameDefinition

Methods inherited from class agi.foundation.infrastructure.DefinitionalObject

areSameDefinition, areSameDefinition, areSameDefinition, areSameDefinition, areSameDefinition, collectionItemsAreSameDefinition, collectionItemsAreSameDefinition, collectionItemsAreSameDefinition, dictionaryItemsAreSameDefinition, freeze, freezeAggregatedObjects, getCollectionHashCode, getCollectionHashCode, getCollectionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDictionaryHashCode, getIsFrozen, isSameDefinition, throwIfFrozen

Methods inherited from class java.lang.Object

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

Constructor Detail

MinimumVarianceDistortionlessResponseBeamformer

public MinimumVarianceDistortionlessResponseBeamformer()

Initializes a new instance.

The BeamDirectionsProvider (get / set) defaults to a default instance of StaticDirectionsProvider with a single default instance of StaticDirection in the StaticDirectionList (get). The beam variance defaults to 3 dB, converted to linear scale.

MinimumVarianceDistortionlessResponseBeamformer

public MinimumVarianceDistortionlessResponseBeamformer(double beamVariance)

Initializes a new instance.

The BeamDirectionsProvider (get / set) defaults to a default instance of StaticDirectionsProvider with a single default instance of StaticDirection in the StaticDirectionList (get).

Parameters:

beamVariance - The beam variance used to constrain the amount of main gain reduction, which can take place in order to null interference.

MinimumVarianceDistortionlessResponseBeamformer

public MinimumVarianceDistortionlessResponseBeamformer(double beamVariance,
                                                       @Nonnull
                                                       DirectionsProvider beamDirectionsProvider)

Initializes a new instance.

Parameters:

beamVariance - The beam variance used to constrain the amount of main gain reduction, which can take place in order to null interference.

beamDirectionsProvider - The directions provider used to determine the directions used to form beams.

Throws:

ArgumentNullException - Thrown when beamDirectionsProvider is null.

MinimumVarianceDistortionlessResponseBeamformer

public MinimumVarianceDistortionlessResponseBeamformer(double beamVariance,
                                                       @Nonnull
                                                       DirectionsProvider beamDirectionsProvider,
                                                       @Nullable
                                                       DirectionsProvider nullDirectionsProvider)

Initializes a new instance.

Parameters:

beamVariance - The beam variance used to constrain the amount of main gain reduction, which can take place in order to null interference.

beamDirectionsProvider - The directions provider used to determine the directions used to form beams.

nullDirectionsProvider - The directions provider used to determine the directions used to form nulls. Allowed to be null.

Throws:

ArgumentNullException - Thrown when beamDirectionsProvider is null.

MinimumVarianceDistortionlessResponseBeamformer

protected MinimumVarianceDistortionlessResponseBeamformer(@Nonnull
                                                          MinimumVarianceDistortionlessResponseBeamformer existingInstance,
                                                          @Nonnull
                                                          CopyContext context)

Initializes a new instance as a copy of an existing instance.

See ICloneWithContext.clone(CopyContext) for more information about how to implement this constructor in a derived class.

Parameters:

existingInstance - The existing instance to copy.

context - A CopyContext that controls the depth of the copy.

Throws:

ArgumentNullException - Thrown when existingInstance or context is null.

Method Detail

clone

public Object clone(CopyContext context)

Clones this object using the specified context.

This method should be implemented to call a copy constructor on the class of the object being cloned. The copy constructor should take the CopyContext as a parameter in addition to the existing instance to copy. The copy constructor should first call CopyContext.addObjectMapping(T, T) to identify the newly constructed instance as a copy of the existing instance. It should then copy all fields, using CopyContext.updateReference(T) to copy any reference fields.

A typical implementation of ICloneWithContext:

public static class MyClass implements ICloneWithContext {
    public MyClass(MyClass existingInstance, CopyContext context) {
        context.addObjectMapping(existingInstance, this);
        someReference = context.updateReference(existingInstance.someReference);
    }

    @Override
    public final Object clone(CopyContext context) {
        return new MyClass(this, context);
    }

    private Object someReference;
}

In general, all fields that are reference types should be copied with a call to CopyContext.updateReference(T). There are a couple of exceptions:

1. Fields that are aggregate parts of the object should always be copied. A referenced object is an aggregate if properties or methods on the object being copied can modify the externally-visible value of the referenced object.
2. If the semantics of the referenced object require that it have a single parent, owner, context, etc., and the object being copied is that parent, owner, or context, then the referenced object should always be copied.

If one of these exceptions applies, the CopyContext should be given an opportunity to update the reference before the reference is copied explicitly. Use CopyContext.updateReference(T) to update the reference. If CopyContext.updateReference(T) returns the original object, indicating that the context does not have a replacement registered, then copy the object manually by invoking a Clone method, a copy constructor, or by manually constructing a new instance and copying the values.

alwaysCopy = context.updateReference(existingInstance.alwaysCopy);
if (existingInstance.alwaysCopy != null && alwaysCopy == existingInstance.alwaysCopy) {
    alwaysCopy = (AlwaysCopy) existingInstance.alwaysCopy.clone(context);
}

If you are implementing an evaluator (a class that implements IEvaluator), the IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) method shares some responsibilities with the copy context constructor. Code duplication can be avoided by doing the following:

1. For references to other evaluators ONLY, simply assign the reference in the constructor instead of calling CopyContext.updateReference(T). You should still call CopyContext.updateReference(T) on any references to non-evaluators.
2. Call IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) as the last line in the constructor and pass it the same CopyContext passed to the constructor.
3. Implement IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) as normal. See the reference documentation for IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) for more information on implementing that method.

public MyClass(MyClass existingInstance, CopyContext context) {
    super(existingInstance, context);
    someReference = context.updateReference(existingInstance.someReference);
    evaluatorReference = existingInstance.evaluatorReference;
    updateEvaluatorReferences(context);
}

@Override
public void updateEvaluatorReferences(CopyContext context) {
    evaluatorReference = context.updateReference(evaluatorReference);
}

@Override
public Object clone(CopyContext context) {
    return new MyClass(this, context);
}

private Object someReference;
private IEvaluator evaluatorReference;

Specified by:

clone in interface ICloneWithContext

Specified by:

clone in class DefinitionalObject

Parameters:

context - The context to use to perform the copy.

Returns:

A new instance which is a copy of this object.

checkForSameDefinition

protected final boolean checkForSameDefinition(PhasedArrayBeamformer other)

Checks to determine if another instance has the same definition as this instance and returns true if it does. Derived classes MUST override this method and check all new fields introduced by the derived class for definitional equivalence. It is NOT necessary to check base class fields because the base class will already have done that. When overriding this method, you should NOT call the base implementation because it will return false for all derived-class instances. Derived classes should check the type of other to preserve the symmetric nature of IEquatableDefinition.isSameDefinition(java.lang.Object).

Specified by:

checkForSameDefinition in class PhasedArrayBeamformer

Parameters:

other - The other instance to compare to this one.

Returns:

true if the two objects are defined equivalently; otherwise false.

checkForSameDefinition

protected boolean checkForSameDefinition(MinimumVarianceDistortionlessResponseBeamformer other)

Checks to determine if another instance has the same definition as this instance and returns true if it does. Derived classes MUST override this method and check all new fields introduced by the derived class for definitional equivalence. It is NOT necessary to check base class fields because the base class will already have done that. When overriding this method, you should NOT call the base implementation because it will return false for all derived-class instances. Derived classes should check the type of other to preserve the symmetric nature of IEquatableDefinition.isSameDefinition(java.lang.Object).

Parameters:

other - The other instance to compare to this one.

Returns:

true if the two objects are defined equivalently; otherwise false.

computeCurrentDefinitionHashCode

protected int computeCurrentDefinitionHashCode()

Computes a hash code based on the current properties of this object. Derived classes MUST override this method and compute a hash code that combines: a unique hash code seed, the base implementation result, and the hash codes of all new fields introduced by the derived class which are used in the MinimumVarianceDistortionlessResponseBeamformer.checkForSameDefinition(agi.foundation.communications.antennas.PhasedArrayBeamformer) method.

Overrides:

computeCurrentDefinitionHashCode in class PhasedArrayBeamformer

Returns:

The computed hash code.

enumerateDependencies

public void enumerateDependencies(DependencyEnumerator enumerator)

Enumerates the dependencies of this object by calling DependencyEnumerator#enumerate(T) for each object that this object directly depends upon. Derived classes which contain additional dependencies MUST override this method, call the base implementation, and enumerate dependencies introduced by the derived class.

Specified by:

enumerateDependencies in interface IEnumerateDependencies

Overrides:

enumerateDependencies in class DefinitionalObject

Parameters:

enumerator - The enumerator that is informed of the dependencies of this object.

getBeamDirectionsProvider

public final DirectionsProvider getBeamDirectionsProvider()

Gets the DirectionsProvider for providing the beam directions.

setBeamDirectionsProvider

public final void setBeamDirectionsProvider(DirectionsProvider value)

Sets the DirectionsProvider for providing the beam directions.

getNullDirectionsProvider

@Nullable
public final DirectionsProvider getNullDirectionsProvider()

Gets the DirectionsProvider for providing the null directions.

This property defaults to null. If not set, the weights produced will not account for null steering.

setNullDirectionsProvider

public final void setNullDirectionsProvider(@Nullable
                                            DirectionsProvider value)

Sets the DirectionsProvider for providing the null directions.

This property defaults to null. If not set, the weights produced will not account for null steering.

getBeamVariance

public final double getBeamVariance()

Gets the beam variance. Value to constrain the amount of main gain reduction, which can take place in order to null interference.

setBeamVariance

public final void setBeamVariance(double value)

Sets the beam variance. Value to constrain the amount of main gain reduction, which can take place in order to null interference.

getBeamWeightsEvaluator

public BeamformerWeightsEvaluator getBeamWeightsEvaluator(EvaluatorGroup group,
                                                          ISignalSource inputSignal,
                                                          Vector linkDirection,
                                                          Axes antennaAxes,
                                                          List<PhasedArrayElement> elementPattern)

Gets a BeamformerWeightsEvaluator which when evaluated produces a ComplexMatrix of element weights.

Specified by:

getBeamWeightsEvaluator in class PhasedArrayBeamformer

Parameters:

group - The group with which to associate the new evaluator. By grouping evaluators that are often evaluated at the same Julian dates, common computations can be performed only once for the entire group instead of multiple times for each evaluator.

inputSignal - The input signal source.

linkDirection - The link direction vector.

antennaAxes - The antenna axes.

elementPattern - The phased array element pattern.

Returns:

An BeamformerWeightsEvaluator instance for evaluating element weights.

Throws:

ArgumentNullException - Thrown if any of the arguments are null.

ArgumentException - Thrown if the elementPattern has a count less than 2.

PropertyInvalidException - Thrown when BeamDirectionsProvider (get / set) is null.