package org.orekit.models.earth;
import org.hipparchus.util.FastMath;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import org.orekit.Utils;
import org.orekit.bodies.GeodeticPoint;
import org.orekit.bodies.OneAxisEllipsoid;
import org.orekit.errors.OrekitException;
import org.orekit.frames.FramesFactory;
import org.orekit.frames.TopocentricFrame;
import org.orekit.utils.Constants;
import org.orekit.utils.IERSConventions;
public class EarthITU453AtmosphereRefractionTest {
private final double onehundredth = 1e-2;
private final double twohundredth = 2e-2;
private final double onethousandth = 1e-3;
private final double epsilon = 1e-15;
// Table (ref. Astronomical Refraction, Michael E. Thomas and Richard I. Joseph)
// (JOHNS HOPKINS APL TECHNICAL DIGEST, VOLUME 17, NUMBER 3 (1996))
// elevation (deg)
private final double[] ref_elevation = new double[] {0.00, 0.25, 0.50, 0.75, 1.00, 1.25, 1.50, 1.75, 2.00, 2.25, 2.50, 2.75, 3.00, 4.50, 5.00,
6.00, 7.00, 8.00, 9.00, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0, 17.0, 18.0, 19.0, 20.0,
25.0, 30.0, 35.0, 50.0, 55.0, 60.0, 65.0, 70.0, 80.0, 90.0};
// refraction correction angle (in arcminutes)
private final double[] ref_refraction = new double[] {34.5, 31.4, 28.7, 26.4, 24.3, 22.5, 20.9, 19.5, 18.3, 17.2, 16.1, 15.2, 14.4, 10.7, 9.90,
8.50, 7.40, 6.60, 5.90, 5.30, 4.90, 4.50, 4.10, 3.80, 3.60, 3.30, 3.10, 2.90, 2.80, 2.60,
2.10, 1.70, 1.40, 0.80, 0.70, 0.60, 0.50, 0.40, 0.20, 0.00};
// Kiruna-2 ESTRACK Station (Sweden)
private TopocentricFrame stationk;
private String namek = "Kiruna-2";
// Hartebeesthoek IGS Station (South Africa)
// lowest elevation angle that verify inequality number 11 : theta0 = -1.039 degree;
private TopocentricFrame stationh;
private String nameh = "Hartebeesthoek";
// Everest Fake Station (China/Nepal)
private TopocentricFrame statione;
private String namee = "Everest";
// Dead Sea Fake Station (Israel)
private TopocentricFrame stationd;
private String named = "Dead Sea";
// Altitude0 Fake Station ()
private TopocentricFrame stationa;
private String namea = "Alt0";
@Before
public void setUp() throws Exception {
Utils.setDataRoot("regular-data:potential:tides");
IERSConventions conventions = IERSConventions.IERS_2010;
OneAxisEllipsoid earth = new OneAxisEllipsoid(Constants.WGS84_EARTH_EQUATORIAL_RADIUS,
Constants.WGS84_EARTH_FLATTENING,
FramesFactory.getITRF(conventions, true));
// Kiruna-2 (Sweden)
final GeodeticPoint kir = new GeodeticPoint(FastMath.toRadians(67.858428),
FastMath.toRadians(20.966880),
385.8);
// Hartebeesthoek (South Africa)
final GeodeticPoint har = new GeodeticPoint(FastMath.toRadians(-24.110243),
FastMath.toRadians(27.685308),
1415.821);
// Everest (fake station)
final GeodeticPoint eve = new GeodeticPoint(FastMath.toRadians(27.988333),
FastMath.toRadians(86.991944),
8848.0);
// Dead Sea (fake station)
final GeodeticPoint des = new GeodeticPoint(FastMath.toRadians(31.500000),
FastMath.toRadians(35.500000),
-422.0);
// Alt0 (fake station)
final GeodeticPoint alt = new GeodeticPoint(FastMath.toRadians(31.500000),
FastMath.toRadians(35.500000),
0.0);
stationk = new TopocentricFrame(earth, kir, namek);
stationh = new TopocentricFrame(earth, har, nameh);
statione = new TopocentricFrame(earth, eve, namee);
stationd = new TopocentricFrame(earth, des, named);
stationa = new TopocentricFrame(earth, alt, namea);
}
@Test
public void testEarthITU453AtmosphereRefractionHighest() throws OrekitException {
// elevation angle of the space station under free-space propagation conditions
final double elevation = FastMath.toRadians(2.0);
// Station altitude
final double altitude = statione.getPoint().getAltitude();
EarthITU453AtmosphereRefraction modelTropo = new EarthITU453AtmosphereRefraction(altitude);
// refraction correction in degrees
double refraction = FastMath.toDegrees(modelTropo.getRefraction(elevation));
Assert.assertEquals(0.11458177523385392, refraction, epsilon);
}
@Test
public void testEarthITU453AtmosphereRefractionLowest() throws OrekitException {
// elevation angle of the space station under free-space propagation conditions
final double elevation = FastMath.toRadians(2.0);
// Station altitude
final double altitude = stationd.getPoint().getAltitude();
EarthITU453AtmosphereRefraction modelTropo = new EarthITU453AtmosphereRefraction(altitude);
// refraction correction in degrees
double refraction = FastMath.toDegrees(modelTropo.getRefraction(elevation));
Assert.assertEquals(0.3550620274090111, refraction, epsilon);
}
@Test
public void testEarthITU453AtmosphereRefraction2degree() throws OrekitException {
// elevation angle of the space station under free-space propagation conditions
final double elevation = FastMath.toRadians(2.0);
// Station altitude
final double altitude = stationk.getPoint().getAltitude();
EarthITU453AtmosphereRefraction modelTropo = new EarthITU453AtmosphereRefraction(altitude);
// refraction correction in degrees
final double refraction = FastMath.toDegrees(modelTropo.getRefraction(elevation));
Assert.assertEquals(refraction, 0.32, onehundredth);
final double thetamin = FastMath.toDegrees(modelTropo.getThetaMin());
Assert.assertEquals(-0.5402509318003884, thetamin, epsilon);
final double theta0 = FastMath.toDegrees(modelTropo.getTheta0());
Assert.assertEquals(-1.4959064751203384, theta0, epsilon);
}
@Test
public void testEarthITU453AtmosphereRefraction4degree() throws OrekitException {
// elevation angle of the space station under free-space propagation conditions
final double elevation = FastMath.toRadians(4.0);
// Station altitude
final double altitude = stationk.getPoint().getAltitude();
EarthITU453AtmosphereRefraction modelTropo = new EarthITU453AtmosphereRefraction(altitude);
// refraction correction in degrees
double refraction = FastMath.toDegrees(modelTropo.getRefraction(elevation));
Assert.assertEquals(0.21, refraction, onehundredth);
}
@Test
public void testEarthITU453AtmosphereRefraction10degree() throws OrekitException {
// elevation angle of the space station under free-space propagation conditions
final double elevation = FastMath.toRadians(10.0);
// Station altitude
final double altitude = stationk.getPoint().getAltitude();
EarthITU453AtmosphereRefraction modelTropo = new EarthITU453AtmosphereRefraction(altitude);
// refraction correction in degrees
double refraction = FastMath.toDegrees(modelTropo.getRefraction(elevation));
Assert.assertEquals(0.10, refraction, twohundredth);
}
@Test
public void testEarthITU453AtmosphereRefraction30degree() throws OrekitException {
// elevation angle of the space station under free-space propagation conditions
final double elevation = FastMath.toRadians(30.0);
// Station altitude
final double altitude = stationk.getPoint().getAltitude();
EarthITU453AtmosphereRefraction modelTropo = new EarthITU453AtmosphereRefraction(altitude);
// refraction correction in degrees
double refraction = FastMath.toDegrees(modelTropo.getRefraction(elevation));
Assert.assertEquals(0.02, refraction, onehundredth);
}
@Test
public void testEarthITU453AtmosphereRefraction90degree() throws OrekitException {
// elevation angle of the space station under free-space propagation conditions
final double elevation = FastMath.toRadians(90.0);
// Station altitude
final double altitude = stationk.getPoint().getAltitude();
EarthITU453AtmosphereRefraction modelTropo = new EarthITU453AtmosphereRefraction(altitude);
// refraction correction in degrees
double refraction = FastMath.toDegrees(modelTropo.getRefraction(elevation));
Assert.assertEquals(0.002, refraction, onethousandth);
}
@Test
public void testEarthITU453AtmosphereRefractionminusdegree() throws OrekitException {
// elevation angle of the space station under free-space propagation conditions
final double elevation = FastMath.toRadians(-10.);
// Station altitude
final double altitude = stationh.getPoint().getAltitude();
EarthITU453AtmosphereRefraction modelTropo = new EarthITU453AtmosphereRefraction(altitude);
// refraction correction in degrees
double refraction = FastMath.toDegrees(modelTropo.getRefraction(elevation));
Assert.assertEquals(1.7367073234643113, refraction, onethousandth);
}
@Test
public void testEarthITU453AtmosphereRefractiontable() throws OrekitException {
// Station altitude
final double altitude = stationa.getPoint().getAltitude();
EarthITU453AtmosphereRefraction modelTropo = new EarthITU453AtmosphereRefraction(altitude);
for (int itab=0; itab<40; itab++) {
// elevation angle of the space station under free-space propagation conditions
final double elevation = FastMath.toRadians(ref_elevation[itab]);
// refraction correction in arcminutes
final double refraction = 60.0 * FastMath.toDegrees(modelTropo.getRefraction(elevation));
Assert.assertEquals(ref_refraction[itab], refraction, 2.1);
}
}
}