BistaticModifierUtil.java
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package org.orekit.estimation.measurements.modifiers;
import java.util.Arrays;
import org.hipparchus.analysis.differentiation.Gradient;
import org.orekit.estimation.measurements.EstimatedMeasurement;
import org.orekit.estimation.measurements.EstimatedMeasurementBase;
import org.orekit.estimation.measurements.GroundStation;
import org.orekit.estimation.measurements.ObservedMeasurement;
import org.orekit.propagation.FieldSpacecraftState;
import org.orekit.propagation.SpacecraftState;
import org.orekit.propagation.integration.AbstractGradientConverter;
import org.orekit.utils.Differentiation;
import org.orekit.utils.ParameterDriver;
import org.orekit.utils.ParameterDriversProvider;
import org.orekit.utils.TimeSpanMap.Span;
/** Utility class for bistatic measurements.
* @author Pascal Parraud
* @since 11.2
*/
class BistaticModifierUtil {
/** Private constructor for utility class.*/
private BistaticModifierUtil() {
// not used
}
/** Apply a modifier to an estimated measurement.
* @param <T> type of the measurement
* @param estimated estimated measurement to modify
* @param emitter emitter station
* @param receiver receiver station
* @param modelEffect model effect
*/
public static <T extends ObservedMeasurement<T>> void modify(final EstimatedMeasurementBase<T> estimated,
final GroundStation emitter, final GroundStation receiver,
final ParametricModelEffect modelEffect) {
// update estimated value taking into account the model effect.
// The model effect delay is directly added to the measurement.
final SpacecraftState state = estimated.getStates()[0];
final double[] newValue = estimated.getEstimatedValue().clone();
newValue[0] += modelEffect.evaluate(emitter, state);
newValue[0] += modelEffect.evaluate(receiver, state);
estimated.setEstimatedValue(newValue);
}
/** Apply a modifier to an estimated measurement.
* @param <T> type of the measurement
* @param estimated estimated measurement to modify
* @param emitter emitter station
* @param receiver receiver station
* @param converter gradient converter
* @param parametricModel parametric modifier model
* @param modelEffect model effect
* @param modelEffectGradient model effect gradient
*/
public static <T extends ObservedMeasurement<T>> void modify(final EstimatedMeasurement<T> estimated,
final ParameterDriversProvider parametricModel,
final AbstractGradientConverter converter,
final GroundStation emitter, final GroundStation receiver,
final ParametricModelEffect modelEffect,
final ParametricModelEffectGradient modelEffectGradient) {
final SpacecraftState state = estimated.getStates()[0];
// update estimated derivatives with Jacobian of the measure wrt state
final FieldSpacecraftState<Gradient> gState = converter.getState(parametricModel);
final Gradient[] gParameters = converter.getParameters(gState, parametricModel);
final Gradient delayUp = modelEffectGradient.evaluate(emitter, gState, gParameters);
final double[] derivativesUp = delayUp.getGradient();
final Gradient delayDown = modelEffectGradient.evaluate(receiver, gState, gParameters);
final double[] derivativesDown = delayDown.getGradient();
// update estimated derivatives with Jacobian of the measure wrt state
final double[][] stateDerivatives = estimated.getStateDerivatives(0);
for (int jcol = 0; jcol < stateDerivatives[0].length; ++jcol) {
stateDerivatives[0][jcol] += derivativesUp[jcol];
stateDerivatives[0][jcol] += derivativesDown[jcol];
}
estimated.setStateDerivatives(0, stateDerivatives);
int index = 0;
for (final ParameterDriver driver : parametricModel.getParametersDrivers()) {
if (driver.isSelected()) {
for (Span<String> span = driver.getNamesSpanMap().getFirstSpan(); span != null; span = span.next()) {
// update estimated derivatives with derivative of the modification wrt model parameters
double parameterDerivative = estimated.getParameterDerivatives(driver, span.getStart())[0];
parameterDerivative += derivativesUp[index + converter.getFreeStateParameters()];
parameterDerivative += derivativesDown[index + converter.getFreeStateParameters()];
estimated.setParameterDerivatives(driver, span.getStart(), parameterDerivative);
index++;
}
}
}
for (final ParameterDriver driver : Arrays.asList(emitter.getEastOffsetDriver(),
emitter.getNorthOffsetDriver(),
emitter.getZenithOffsetDriver())) {
if (driver.isSelected()) {
for (Span<String> span = driver.getNamesSpanMap().getFirstSpan(); span != null; span = span.next()) {
// update estimated derivatives with derivative of the modification wrt station parameters
double parameterDerivative = estimated.getParameterDerivatives(driver, span.getStart())[0];
parameterDerivative += Differentiation.differentiate((d, t) -> modelEffect.evaluate(emitter, state),
3, 10.0 * driver.getScale()).value(driver, state.getDate());
estimated.setParameterDerivatives(driver, span.getStart(), parameterDerivative);
}
}
}
for (final ParameterDriver driver : Arrays.asList(receiver.getClockOffsetDriver(),
receiver.getEastOffsetDriver(),
receiver.getNorthOffsetDriver(),
receiver.getZenithOffsetDriver())) {
if (driver.isSelected()) {
for (Span<String> span = driver.getNamesSpanMap().getFirstSpan(); span != null; span = span.next()) {
// update estimated derivatives with derivative of the modification wrt station parameters
double parameterDerivative = estimated.getParameterDerivatives(driver, span.getStart())[0];
parameterDerivative += Differentiation.differentiate((d, t) -> modelEffect.evaluate(receiver, state),
3, 10.0 * driver.getScale()).value(driver, state.getDate());
estimated.setParameterDerivatives(driver, span.getStart(), parameterDerivative);
}
}
}
// modify the value
modify(estimated, emitter, receiver, modelEffect);
}
}