/* Copyright 2002-2017 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.
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package fr.cs.examples.frames;
import java.util.Locale;
import org.hipparchus.geometry.euclidean.threed.Vector3D;
import org.hipparchus.util.FastMath;
import org.orekit.bodies.BodyShape;
import org.orekit.bodies.GeodeticPoint;
import org.orekit.bodies.OneAxisEllipsoid;
import org.orekit.errors.OrekitException;
import org.orekit.frames.Frame;
import org.orekit.frames.FramesFactory;
import org.orekit.frames.TopocentricFrame;
import org.orekit.orbits.CartesianOrbit;
import org.orekit.orbits.Orbit;
import org.orekit.propagation.Propagator;
import org.orekit.propagation.analytical.KeplerianPropagator;
import org.orekit.time.AbsoluteDate;
import org.orekit.time.TimeScale;
import org.orekit.time.TimeScalesFactory;
import org.orekit.utils.Constants;
import org.orekit.utils.IERSConventions;
import org.orekit.utils.PVCoordinates;
import fr.cs.examples.Autoconfiguration;
/** Orekit tutorial for basic frames support.
* <p>This tutorial shows a simple usage of frames and transforms.</p>
* @author Pascal Parraud
*/
public class Frames1 {
public static void main(String[] args) {
try {
// configure Orekit
Autoconfiguration.configureOrekit();
// Initial state definition : date, orbit
TimeScale utc = TimeScalesFactory.getUTC();
AbsoluteDate initialDate = new AbsoluteDate(2008, 10, 01, 0, 0, 00.000, utc);
double mu = 3.986004415e+14; // gravitation coefficient
Frame inertialFrame = FramesFactory.getEME2000(); // inertial frame for orbit definition
Vector3D posisat = new Vector3D(-6142438.668, 3492467.560, -25767.25680);
Vector3D velosat = new Vector3D(505.8479685, 942.7809215, 7435.922231);
PVCoordinates pvsat = new PVCoordinates(posisat, velosat);
Orbit initialOrbit = new CartesianOrbit(pvsat, inertialFrame, initialDate, mu);
// Propagator : consider a simple keplerian motion
Propagator kepler = new KeplerianPropagator(initialOrbit);
// Earth and frame
Frame earthFrame = FramesFactory.getITRF(IERSConventions.IERS_2010, true);
BodyShape earth = new OneAxisEllipsoid(Constants.WGS84_EARTH_EQUATORIAL_RADIUS,
Constants.WGS84_EARTH_FLATTENING,
earthFrame);
// Station
final double longitude = FastMath.toRadians(45.);
final double latitude = FastMath.toRadians(25.);
final double altitude = 0.;
final GeodeticPoint station = new GeodeticPoint(latitude, longitude, altitude);
final TopocentricFrame staF = new TopocentricFrame(earth, station, "station");
System.out.println(" time doppler (m/s)");
// Stop date
final AbsoluteDate finalDate = new AbsoluteDate(initialDate, 6000, utc);
// Loop
AbsoluteDate extrapDate = initialDate;
while (extrapDate.compareTo(finalDate) <= 0) {
// We can simply get the position and velocity of spacecraft in station frame at any time
PVCoordinates pvInert = kepler.propagate(extrapDate).getPVCoordinates();
PVCoordinates pvStation = inertialFrame.getTransformTo(staF, extrapDate).transformPVCoordinates(pvInert);
// And then calculate the doppler signal
double doppler = Vector3D.dotProduct(pvStation.getPosition(), pvStation.getVelocity()) / pvStation.getPosition().getNorm();
System.out.format(Locale.US, "%s %9.3f%n", extrapDate, doppler);
extrapDate = extrapDate.shiftedBy(600);
}
} catch (OrekitException oe) {
System.err.println(oe.getMessage());
}
}
}