MeasurementObject.java

/* Copyright 2002-2025 Brianna Aubin
 * Licensed to Hawkeye 360 (HE360) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * CS licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.orekit.estimation.measurements;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
//import java.util.Map;

//import org.hipparchus.analysis.differentiation.Gradient;
import org.hipparchus.util.FastMath;
//import org.orekit.time.AbsoluteDate;
import org.orekit.time.clocks.QuadraticClockModel;
//import org.orekit.time.clocks.QuadraticFieldClockModel;
import org.orekit.utils.ParameterDriver;

/** Abstract class underlying both observed and observing measurement
 * objects.  Contains the QuadraticClockModel and the ability to store a
 * master list of all parameter drivers associated with the object.
 *
 * @author Brianna Aubin
 * @since 14.0
 */

abstract class MeasurementObject {

    /** Suffix for ground station position and clock offset parameters names. */
    public static final String OFFSET_SUFFIX = "-offset";

    /** Suffix for ground clock drift parameters name. */
    public static final String DRIFT_SUFFIX = "-drift";

    /** Suffix for ground clock drift parameters name.
     * @since 12.1
     */
    public static final String ACCELERATION_SUFFIX = "-acceleration";

    /** Checkstyle is annoying sometimes. */
    private static final String CLOCK_STRING = "-clock";

    /** Clock offset scaling factor.
     * <p>
     * We use a power of 2 to avoid numeric noise introduction
     * in the multiplications/divisions sequences.
     * </p>
     */
    private static final double CLOCK_OFFSET_SCALE = FastMath.scalb(1.0, -10);

    /** Stores quadratic clock model. */
    private final QuadraticClockModel quadraticClockModel;

    /** Stores list of all ParameterDriver values. */
    private final List<ParameterDriver> parameterDrivers = new ArrayList<>();

    /** Name of the satellite. */
    private final String name;

    /** Simple constructor.
     * @param name name of MeasurementObject
     */
    protected MeasurementObject(final String name) {
        this(name, createEmptyQuadraticClock(name));
    }

    /** Simple constructor.
     * @param name name of MeasurementObject
     * @param quadraticClock clock belonging to MeasurementObject
     */
    protected MeasurementObject(final String name, final QuadraticClockModel quadraticClock) {

        // Initialize member variables
        this.name = name;
        this.quadraticClockModel = quadraticClock;

        // Add clock parameters
        parameterDrivers.add(quadraticClockModel.getClockOffsetDriver());
        parameterDrivers.add(quadraticClockModel.getClockDriftDriver());
        parameterDrivers.add(quadraticClockModel.getClockAccelerationDriver());
    }

    /** Get the MeasurementObject name.
     * @return name for the object
     * @since 12.1
     */
    public final String getName() {
        return name;
    }

    /** Get the clock offset driver.
     * @return clock offset driver
     */
    public final ParameterDriver getClockOffsetDriver() {
        return quadraticClockModel.getClockOffsetDriver();
    }

    /** Get the clock drift driver.
     * @return clock drift driver
     */
    public final ParameterDriver getClockDriftDriver() {
        return quadraticClockModel.getClockDriftDriver();
    }

    /** Get the clock acceleration driver.
     * @return clock acceleration driver
     */
    public final ParameterDriver getClockAccelerationDriver() {
        return quadraticClockModel.getClockAccelerationDriver();
    }

    /** Creates an quadratic clock with zero displacement.
     * @param name name of object that is holding the clock
     * @return new quadratic clock model
     */
    protected static QuadraticClockModel createEmptyQuadraticClock(final String name) {
        return new QuadraticClockModel(new ParameterDriver(name + CLOCK_STRING + OFFSET_SUFFIX,
                                                    0.0, CLOCK_OFFSET_SCALE,
                                                    Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY),
                                           new ParameterDriver(name + CLOCK_STRING + DRIFT_SUFFIX,
                                                    0.0, CLOCK_OFFSET_SCALE,
                                                    Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY),
                                           new ParameterDriver(name + CLOCK_STRING + ACCELERATION_SUFFIX,
                                                    0.0, CLOCK_OFFSET_SCALE,
                                                    Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY));
    }

    /** Get a quadratic clock model valid at some date.
     * @return quadratic clock model
     * @since 12.1
     */
    public final QuadraticClockModel getQuadraticClockModel() {
        return quadraticClockModel;
    }

    /** Get emitting satellite clock provider.
     * @param freeParameters total number of free parameters in the gradient
     * @param date time of computations
     * @param indices indices of the differentiation parameters in derivatives computations,
     * must be span name and not driver name
     * @return emitting satellite clock provider
     */
    /*
    protected QuadraticFieldClockModel<Gradient> getQuadraticFieldClock(final int freeParameters,
                                                                        final AbsoluteDate date,
                                                                        final Map<String, Integer> indices) {
        return getQuadraticClockModel().toGradientModel(freeParameters, indices, date);
    }
    */

    /** Return all parameter drivers associated with the MeasurementObject.
     * @return list of parameter drivers
     */
    public List<ParameterDriver> getParametersDrivers() {
        return Collections.unmodifiableList(parameterDrivers);
    }

    /**
     * Add a single parameter.
     * @param parameterDriver parameter being added to the MeasurementObject
     */
    protected final void addParameterDriver(final ParameterDriver parameterDriver) {
        parameterDrivers.add(parameterDriver);
    }
}