agi.foundation.communications.signalprocessing

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

Class VariableGainAmplifier

java.lang.Object

agi.foundation.infrastructure.DefinitionalObject

agi.foundation.communications.signalprocessing.SignalProcessor

agi.foundation.communications.signalprocessing.Amplifier

agi.foundation.communications.signalprocessing.VariableGainAmplifier

All Implemented Interfaces:

ISignalSource, ISignalOutputService, ICloneWithContext, IEnumerateDependencies, IEquatableDefinition, IFreezable, IServiceProvider

public class VariableGainAmplifier
extends Amplifier

Model of a non-linear amplifier where the output power is determined by an input back-off/output back-off (IBO/OBO) curve and intermodulation noise temperature can be added to the carrier using an input back-off/carrier to intermodulation noise spectral density (IBO/(C/No)_Im) curve.

The VariableGainAmplifier class can be used to model non-linear amplifiers operating with a one or more signals (carriers) at the input. The output power and intermodulation noise for each carrier is determined by a set of input back-off curves, one for the amplifier transfer characteristic and one for the carrier to noise spectral density due to intermodulations ((C/No)_Im). The model contains a list of these back-off curve sets, where the index of the list represents the number of carriers present at the input of the amplifier. For example, if two carriers are present at the input of the amplifier, the set of curves at the second index of the list will be used to determine the output power and intermodulation noise for each carrier.

The above figure shows the variation of OBO as a function of IBO, for single carrier operation and multi-carrier operation. The model defines IBO as the carrier power at the input of the amplifier normalized by the saturation input power (Pi/Pi_sat). OBO is defined as carrier power at the output of the amplifier normalized by the saturation output power (Po/Po_sat). In determining the output power for each carrier, the model first selects the set of back-off curves to be used from the list, based on the number of carriers at the amplifier input. From the selected curves set, the IBO/OBO curve is evaluated at the computed IBO for each carrier to determine the OBO. From the carriers OBO, the output power is determined by multiplying by the saturation output power of the amplifier. If an OBO greater than 1.0 is computed for a carrier, the OBO is reset to 1.0 so that the output power will never exceed the saturation output power.

The above figure shows the variation of (C/No)_Im as a function of IBO and number of carriers. In determining the noise temperature due to intermodulation for each carrier, again the model first selects the set of back-off curves based on the number of carriers. If the IBO/(C/No)_Im curve of the set was set to null, intermodulation noise is not factored into the noise for each carrier. From the selected curves set, the IBO/(C/No)_Im curve is evaluated at the computed IBO for each carrier to determine the (C/No)_Im. The noise temperature due to intermodulation is then computed by dividing the carrier power by the (C/No)_Im times Boltzmann's constant. The new noise temperature of the carrier is then computed by adding the noise temperature due to intermodulation and the noise temperature of the amplifier and multiplying the result by the gain of the amplifier (Gain = Po/Pi).

Reference:

Maral, G. and M. Bousquet. Satellite Communications Systems: Systems,Techniques and Technology, 3rd Edition. Chichester, England, 1998.

Constructor Summary

Constructors

Modifier	Constructor and Description
	VariableGainAmplifier() Initializes a new instance.
	VariableGainAmplifier(SignalProcessor inputSignalProcessor) Initializes a new instance from the given signal input.
	VariableGainAmplifier(SignalProcessor inputSignalProcessor, double saturatedInputPower, double saturatedOutputPower, double noiseFactor, double referenceTemperature) Initializes a new instance from the given signal input, saturated input power, saturated output power, noise factor, and reference temperature.
	VariableGainAmplifier(SignalProcessor inputSignalProcessor, double saturatedInputPower, double saturatedOutputPower, double noiseFactor, double referenceTemperature, List<VariableGainAmplifierBackoffCurves> backoffCurvesList) Initializes a new instance from the given signal input, saturated input power, saturated output power, noise factor, reference temperature, and back-off curves list.
protected	VariableGainAmplifier(VariableGainAmplifier 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(Amplifier other) Checks to determine if another instance has the same definition as this instance and returns true if it does.
protected boolean	checkForSameDefinition(VariableGainAmplifier 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.
List<VariableGainAmplifierBackoffCurves>	getBackoffCurvesList() Gets the list of back-off curves.
SignalProcessor	getInputSignalProcessor() Gets the signal processor which produces the set of signals which this processor modifies.
double	getSaturatedInputPower() Gets the saturated input power.
double	getSaturatedOutputPower() Gets the saturated output power.
SignalEvaluator	getSignalEvaluator(EvaluatorGroup group, SignalPropagationGraph graph) Get an evaluator which modifies the InputSignalProcessor (get / set) by applying the computed amplifier gain.
void	setInputSignalProcessor(SignalProcessor value) Sets the signal processor which produces the set of signals which this processor modifies.
void	setSaturatedInputPower(double value) Sets the saturated input power.
void	setSaturatedOutputPower(double value) Sets the saturated output power.

Methods inherited from class agi.foundation.communications.signalprocessing.Amplifier

checkForSameDefinition, getNoiseFactor, getNoiseTemperature, getReferenceTemperature, setNoiseFactor, setReferenceTemperature

Methods inherited from class agi.foundation.communications.signalprocessing.SignalProcessor

checkForSameDefinition, getProcessingDelay, getService, getSignalEvaluator, getSignalOutput

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

VariableGainAmplifier

public VariableGainAmplifier()

Initializes a new instance.

VariableGainAmplifier

public VariableGainAmplifier(SignalProcessor inputSignalProcessor)

Initializes a new instance from the given signal input.

Parameters:

inputSignalProcessor - The signal processor producing the signal to be amplified.

VariableGainAmplifier

public VariableGainAmplifier(SignalProcessor inputSignalProcessor,
                             double saturatedInputPower,
                             double saturatedOutputPower,
                             double noiseFactor,
                             double referenceTemperature)

Initializes a new instance from the given signal input, saturated input power, saturated output power, noise factor, and reference temperature.

Parameters:

inputSignalProcessor - The signal processor producing the signal to be amplified.

saturatedInputPower - The saturated input power of the amplifier.

saturatedOutputPower - The saturated output power of the amplifier. The output power of the amplifier will never exceed this value.

noiseFactor - The noise factor of the amplifier.

referenceTemperature - The reference temperature of the amplifier.

VariableGainAmplifier

public VariableGainAmplifier(SignalProcessor inputSignalProcessor,
                             double saturatedInputPower,
                             double saturatedOutputPower,
                             double noiseFactor,
                             double referenceTemperature,
                             @Nonnull
                             List<VariableGainAmplifierBackoffCurves> backoffCurvesList)

Initializes a new instance from the given signal input, saturated input power, saturated output power, noise factor, reference temperature, and back-off curves list.

Parameters:

inputSignalProcessor - The signal processor producing the signal to be amplified.

saturatedInputPower - The saturated input power of the amplifier.

saturatedOutputPower - The saturated output power of the amplifier. The output power of the amplifier will never exceed this value.

noiseFactor - The noise factor of the amplifier.

referenceTemperature - The reference temperature of the amplifier.

backoffCurvesList - The list of back-off curves. The index of this list represents the number of carriers at the input of the amplifier. For example, if there are two carriers present at the input of the amplifier, the set of curves at the second index of the list will be used to compute the amplifier back-off and intermodulation noise. If the number of carriers present at the input of the amplifier is greater than the list length, the last set of back-off curves will be used to compute the amplifier back-off and intermodulation noise.

Throws:

ArgumentNullException - Thrown when backoffCurvesList is null

VariableGainAmplifier

protected VariableGainAmplifier(@Nonnull
                                VariableGainAmplifier 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(Amplifier 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 Amplifier

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(VariableGainAmplifier 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 VariableGainAmplifier.checkForSameDefinition(agi.foundation.communications.signalprocessing.Amplifier) method.

Overrides:

computeCurrentDefinitionHashCode in class Amplifier

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.

getSaturatedInputPower

public final double getSaturatedInputPower()

Gets the saturated input power.

setSaturatedInputPower

public final void setSaturatedInputPower(double value)

Sets the saturated input power.

getSaturatedOutputPower

public final double getSaturatedOutputPower()

Gets the saturated output power.

setSaturatedOutputPower

public final void setSaturatedOutputPower(double value)

Sets the saturated output power.

getInputSignalProcessor

public SignalProcessor getInputSignalProcessor()

Gets the signal processor which produces the set of signals which this processor modifies.

Specified by:

getInputSignalProcessor in class SignalProcessor

setInputSignalProcessor

public void setInputSignalProcessor(SignalProcessor value)

Sets the signal processor which produces the set of signals which this processor modifies.

Specified by:

setInputSignalProcessor in class SignalProcessor

getBackoffCurvesList

@Nonnull
public final List<VariableGainAmplifierBackoffCurves> getBackoffCurvesList()

Gets the list of back-off curves.

The index of this list represents the number of carriers at the input of the amplifier. For example, if there are two carriers present at the input of the amplifier, the set of curves at the second index of the list will be used to compute the amplifier back-off and intermodulation noise. If the number of carriers present at the input of the amplifier is greater than the list length, the last set of back-off curves will be used to compute the amplifier back-off and intermodulation noise. If the input back-off/carrier to noise spectral density (IBO/(C/(No)Im)) curve is null, intermodulation noise is not added to the carrier.

getSignalEvaluator

public SignalEvaluator getSignalEvaluator(EvaluatorGroup group,
                                          SignalPropagationGraph graph)

Get an evaluator which modifies the InputSignalProcessor (get / set) by applying the computed amplifier gain.

Specified by:

getSignalEvaluator in interface ISignalSource

Specified by:

getSignalEvaluator in class SignalProcessor

Parameters:

group - The evaluator group in which to create the evaluator.

graph - The graph of the communication links used in the analysis.

Returns:

An evaluator which modifies the InputSignalProcessor (get / set) by applying the computed amplifier gain.

Throws:

ArgumentNullException - Thrown when group or graph is null.

PropertyInvalidException - Thrown if the InputSignalProcessor (get / set) is null.

PropertyInvalidException - Thrown if NoiseTemperature (get) is less than zero.

PropertyInvalidException - Thrown if the BackoffCurvesList (get) count is zero.