TLEPropagatorBuilder.java

/* Copyright 2002-2016 CS Systèmes d'Information
 * Licensed to CS Systèmes d'Information (CS) 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.propagation.conversion;

import java.util.Iterator;

import org.apache.commons.math3.util.FastMath;
import org.apache.commons.math3.util.MathUtils;
import org.orekit.errors.OrekitException;
import org.orekit.errors.OrekitIllegalArgumentException;
import org.orekit.frames.FramesFactory;
import org.orekit.orbits.KeplerianOrbit;
import org.orekit.orbits.Orbit;
import org.orekit.orbits.OrbitType;
import org.orekit.orbits.PositionAngle;
import org.orekit.propagation.Propagator;
import org.orekit.propagation.analytical.tle.TLE;
import org.orekit.propagation.analytical.tle.TLEPropagator;
import org.orekit.time.AbsoluteDate;

/** Builder for TLEPropagator.
 * @author Pascal Parraud
 * @since 6.0
 */
public class TLEPropagatorBuilder extends AbstractPropagatorBuilder {

    /** Parameter name for B* coefficient. */
    public static final String B_STAR = "BSTAR";

    /** Satellite number. */
    private final int satelliteNumber;

    /** Classification (U for unclassified). */
    private final char classification;

    /** Launch year (all digits). */
    private final int launchYear;

    /** Launch number. */
    private final int launchNumber;

    /** Launch piece. */
    private final String launchPiece;

    /** Element number. */
    private final int elementNumber;

    /** Revolution number at epoch. */
    private final int revolutionNumberAtEpoch;

    /** Ballistic coefficient. */
    private double bStar;

    /** Build a new instance.
     * @param satelliteNumber satellite number
     * @param classification classification (U for unclassified)
     * @param launchYear launch year (all digits)
     * @param launchNumber launch number
     * @param launchPiece launch piece
     * @param elementNumber element number
     * @param revolutionNumberAtEpoch revolution number at epoch
     * @throws OrekitException if the TEME frame cannot be set
     * @deprecated as of 7.1, replaced with {@link #TLEPropagatorBuilder(int,
     * char, int, int, String, int, int, OrbitType, PositionAngle)}
     */
    @Deprecated
    public TLEPropagatorBuilder(final int satelliteNumber,
                                final char classification,
                                final int launchYear,
                                final int launchNumber,
                                final String launchPiece,
                                final int elementNumber,
                                final int revolutionNumberAtEpoch)
        throws OrekitException {
        this(satelliteNumber, classification, launchYear, launchNumber, launchPiece,
             elementNumber, revolutionNumberAtEpoch, OrbitType.CARTESIAN, PositionAngle.TRUE);
    }

    /** Build a new instance.
     * @param satelliteNumber satellite number
     * @param classification classification (U for unclassified)
     * @param launchYear launch year (all digits)
     * @param launchNumber launch number
     * @param launchPiece launch piece
     * @param elementNumber element number
     * @param revolutionNumberAtEpoch revolution number at epoch
     * @param orbitType orbit type to use
     * @param positionAngle position angle type to use
     * @throws OrekitException if the TEME frame cannot be set
     * @since 7.1
     */
    public TLEPropagatorBuilder(final int satelliteNumber,
                                final char classification,
                                final int launchYear,
                                final int launchNumber,
                                final String launchPiece,
                                final int elementNumber,
                                final int revolutionNumberAtEpoch,
                                final OrbitType orbitType, final PositionAngle positionAngle)
        throws OrekitException {
        super(FramesFactory.getTEME(), TLEPropagator.getMU(), orbitType, positionAngle);
        addSupportedParameter(B_STAR);
        this.satelliteNumber         = satelliteNumber;
        this.classification          = classification;
        this.launchYear              = launchYear;
        this.launchNumber            = launchNumber;
        this.launchPiece             = launchPiece;
        this.elementNumber           = elementNumber;
        this.revolutionNumberAtEpoch = revolutionNumberAtEpoch;
        this.bStar                   = 0.0;
    }

    /** {@inheritDoc} */
    public Propagator buildPropagator(final AbsoluteDate date, final double[] parameters)
        throws OrekitException {

        // create the orbit
        checkParameters(parameters);
        final Orbit orb = createInitialOrbit(date, parameters);

        // we really need a Keplerian orbit type
        final KeplerianOrbit kep = (KeplerianOrbit) OrbitType.KEPLERIAN.convertType(orb);

        final Iterator<String> freeItr = getFreeParameters().iterator();
        for (int i = 6; i < parameters.length; i++) {
            final String free = freeItr.next();
            for (String available : getSupportedParameters()) {
                if (free.equals(available)) {
                    setParameter(free, parameters[i]);
                }
            }
        }

        final TLE tle = new TLE(satelliteNumber, classification, launchYear, launchNumber, launchPiece,
                                TLE.DEFAULT, elementNumber, date,
                                kep.getKeplerianMeanMotion(), 0.0, 0.0,
                                kep.getE(), MathUtils.normalizeAngle(orb.getI(), FastMath.PI),
                                MathUtils.normalizeAngle(kep.getPerigeeArgument(), FastMath.PI),
                                MathUtils.normalizeAngle(kep.getRightAscensionOfAscendingNode(), FastMath.PI),
                                MathUtils.normalizeAngle(kep.getMeanAnomaly(), FastMath.PI),
                                revolutionNumberAtEpoch, bStar);

        return TLEPropagator.selectExtrapolator(tle);
    }

    /** {@inheritDoc} */
    @Override
    public double getParameter(final String name)
        throws OrekitIllegalArgumentException {
        if (B_STAR.equals(name)) {
            return bStar;
        } else {
            return super.getParameter(name);
        }
    }

    /** {@inheritDoc} */
    @Override
    public void setParameter(final String name, final double value)
        throws OrekitIllegalArgumentException {
        if (B_STAR.equals(name)) {
            bStar = value;
        } else {
            super.setParameter(name, value);
        }
    }

}