From 225bb703318e62088c10967e6b2a2c31b3810d93 Mon Sep 17 00:00:00 2001
From: Luc Maisonobe <luc@orekit.org>
Date: Thu, 17 Jan 2019 17:19:55 +0100
Subject: [PATCH] Added a way to manage clock corrections from GPSPropagator.
---
src/main/java/org/orekit/gnss/GPSAlmanac.java | 12 +-
.../gnss/ClockCorrectionsProvider.java | 115 ++++++++++++++++++
.../analytical/gnss/GPSOrbitalElements.java | 82 +++++++++++++
src/site/xdoc/changes.xml | 15 ++-
.../gnss/GPSOrbitalElementsTest.java | 60 +++++++++
.../analytical/gnss/GPSPropagatorTest.java | 23 ++++
6 files changed, 296 insertions(+), 11 deletions(-)
create mode 100644 src/main/java/org/orekit/propagation/analytical/gnss/ClockCorrectionsProvider.java
create mode 100644 src/test/java/org/orekit/propagation/analytical/gnss/GPSOrbitalElementsTest.java
diff --git a/src/main/java/org/orekit/gnss/GPSAlmanac.java b/src/main/java/org/orekit/gnss/GPSAlmanac.java
index b9b17f799..601421121 100644
--- a/src/main/java/org/orekit/gnss/GPSAlmanac.java
+++ b/src/main/java/org/orekit/gnss/GPSAlmanac.java
@@ -232,20 +232,12 @@ public class GPSAlmanac implements GPSOrbitalElements {
return 0;
}
- /**
- * Gets the Zeroth Order Clock Correction.
- *
- * @return the Zeroth Order Clock Correction (s)
- */
+ @Override
public double getAf0() {
return af0;
}
- /**
- * Gets the First Order Clock Correction.
- *
- * @return the First Order Clock Correction (s/s)
- */
+ @Override
public double getAf1() {
return af1;
}
diff --git a/src/main/java/org/orekit/propagation/analytical/gnss/ClockCorrectionsProvider.java b/src/main/java/org/orekit/propagation/analytical/gnss/ClockCorrectionsProvider.java
new file mode 100644
index 000000000..f92325a3c
--- /dev/null
+++ b/src/main/java/org/orekit/propagation/analytical/gnss/ClockCorrectionsProvider.java
@@ -0,0 +1,115 @@
+/* Copyright 2002-2019 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.analytical.gnss;
+
+import org.hipparchus.geometry.euclidean.threed.Vector3D;
+import org.orekit.propagation.AdditionalStateProvider;
+import org.orekit.propagation.SpacecraftState;
+import org.orekit.time.AbsoluteDate;
+import org.orekit.time.GPSDate;
+import org.orekit.utils.Constants;
+import org.orekit.utils.PVCoordinates;
+
+/** Provider for clock corrections as additional states.
+ * <p>
+ * The value of this additional state is a three elements array containing
+ * </p>
+ * <ul>
+ * <li>at index 0, the polynomial satellite clock model
+ * Δtₛₐₜ = {@link GPSOrbitalElements#getAf0() a₀} +
+ * {@link GPSOrbitalElements#getAf1() a₁} (t - {@link GPSOrbitalElements#getToc() toc}) +
+ * {@link GPSOrbitalElements#getAf1() a₂} (t - {@link GPSOrbitalElements#getToc() toc})²
+ * </li>
+ * <li>at index 1 the relativistic clock correction due to eccentricity</li>
+ * <li>at index 2 the estimated group delay differential {@link GPSOrbitalElements#getTGD() TGD} for L1-L2 correction</li>
+ * </ul>
+ * @author Luc Maisonobe
+ * @since 9.3
+ */
+public class ClockCorrectionsProvider implements AdditionalStateProvider {
+
+ /** Name of the additional state for satellite clock corrections.
+ * @since 9.3
+ */
+ public static final String CLOCK_CORRECTIONS = "";
+
+ /** Duration of the GPS cycle in seconds. */
+ private static final double GPS_CYCLE_DURATION = GPSOrbitalElements.GPS_WEEK_IN_SECONDS *
+ GPSOrbitalElements.GPS_WEEK_NB;
+ /** The GPS orbital elements. */
+ private final GPSOrbitalElements gpsOrbit;
+
+ /** Clock reference epoch. */
+ private final AbsoluteDate clockRef;
+
+ /** Simple constructor.
+ * @param gpsOrbit GPS orbital elements
+ */
+ public ClockCorrectionsProvider(final GPSOrbitalElements gpsOrbit) {
+ this.gpsOrbit = gpsOrbit;
+ this.clockRef = new GPSDate(gpsOrbit.getWeek(), gpsOrbit.getToc() * 1000.0).getDate();
+ }
+
+ /** {@inheritDoc} */
+ @Override
+ public String getName() {
+ return CLOCK_CORRECTIONS;
+ }
+
+ /**
+ * Get the duration from clock Reference epoch.
+ * <p>This takes the GPS week roll-over into account.</p>
+ *
+ * @param date the considered date
+ * @return the duration from clock Reference epoch (s)
+ */
+ private double getDT(final AbsoluteDate date) {
+ // Time from ephemeris reference epoch
+ double dt = date.durationFrom(clockRef);
+ // Adjusts the time to take roll over week into account
+ while (dt > 0.5 * GPS_CYCLE_DURATION) {
+ dt -= GPS_CYCLE_DURATION;
+ }
+ while (dt < -0.5 * GPS_CYCLE_DURATION) {
+ dt += GPS_CYCLE_DURATION;
+ }
+ // Returns the time from ephemeris reference epoch
+ return dt;
+ }
+
+ /** {@inheritDoc} */
+ @Override
+ public double[] getAdditionalState(final SpacecraftState state) {
+
+ // polynomial clock model
+ final double dt = getDT(state.getDate());
+ final double dtSat = gpsOrbit.getAf0() + dt * (gpsOrbit.getAf1() + dt * gpsOrbit.getAf2());
+
+ // relativistic effect due to eccentricity
+ final PVCoordinates pv = state.getPVCoordinates();
+ final double dtRel = -2 * Vector3D.dotProduct(pv.getPosition(), pv.getVelocity()) /
+ (Constants.SPEED_OF_LIGHT * Constants.SPEED_OF_LIGHT);
+
+ // estimated group delay differential
+ final double tg = gpsOrbit.getTGD();
+
+ return new double[] {
+ dtSat, dtRel, tg
+ };
+ }
+
+}
diff --git a/src/main/java/org/orekit/propagation/analytical/gnss/GPSOrbitalElements.java b/src/main/java/org/orekit/propagation/analytical/gnss/GPSOrbitalElements.java
index 65c5484f7..ff6e1807f 100644
--- a/src/main/java/org/orekit/propagation/analytical/gnss/GPSOrbitalElements.java
+++ b/src/main/java/org/orekit/propagation/analytical/gnss/GPSOrbitalElements.java
@@ -167,4 +167,86 @@ public interface GPSOrbitalElements extends TimeStamped {
*/
double getCis();
+ /**
+ * Gets the Issue Of Data Clock (IODC).
+ *
+ * @return the Issue Of Data Clock (IODC)
+ * @since 9.3
+ */
+ default int getIODC() {
+ return 0;
+ }
+
+ /**
+ * Gets the Issue Of Data Ephemeris (IODE).
+ *
+ * @return the Issue Of Data Ephemeris (IODE)
+ * @since 9.3
+ */
+ default int getIODE() {
+ return 0;
+ }
+
+ /**
+ * Gets the Zeroth Order Clock Correction.
+ *
+ * @return the Zeroth Order Clock Correction (s)
+ * @see #getAf1()
+ * @see #getAf2()
+ * @see #getToc()
+ * @since 9.3
+ */
+ default double getAf0() {
+ return 0.0;
+ }
+
+ /**
+ * Gets the First Order Clock Correction.
+ *
+ * @return the First Order Clock Correction (s/s)
+ * @see #getAf0()
+ * @see #getAf2()
+ * @see #getToc()
+ * @since 9.3
+ */
+ default double getAf1() {
+ return 0.0;
+ }
+
+ /**
+ * Gets the Second Order Clock Correction.
+ *
+ * @return the Second Order Clock Correction (s/s²)
+ * @see #getAf0()
+ * @see #getAf1()
+ * @see #getToc()
+ * @since 9.3
+ */
+ default double getAf2() {
+ return 0.0;
+ }
+
+ /**
+ * Gets the clock correction reference time toc.
+ *
+ * @return the clock correction reference time (s)
+ * @see #getAf0()
+ * @see #getAf1()
+ * @see #getAf2()
+ * @since 9.3
+ */
+ default double getToc() {
+ return 0.0;
+ }
+
+ /**
+ * Gets the estimated group delay differential TGD for L1-L2 correction.
+ *
+ * @return the estimated group delay differential TGD for L1-L2 correction (s)
+ * @since 9.3
+ */
+ default double getTGD() {
+ return 0.0;
+ }
+
}
diff --git a/src/site/xdoc/changes.xml b/src/site/xdoc/changes.xml
index 7f6c5d4ef..bc40741a9 100644
--- a/src/site/xdoc/changes.xml
+++ b/src/site/xdoc/changes.xml
@@ -20,7 +20,20 @@
<title>Orekit Changes</title>
</properties>
<body>
- <release version="TBD" date="TBD" description="TBD">
+ <release version="9.3" date="2019-01-21" description="Version 9.3 is a minor version of Orekit.
+ It includes both new features and bug fixes. New features introduced in 9.3 are: a new GPSDate class,
+ changed OrekitException from checked to unchecked exceptions, parameter drivers scales and reference
+ value can be changed, access to Kalman filter internal matrices, position-only measurements in orbit determination,
+ support for unofficial versions 2.12 and 2.20 of Rinex files (mainly for spaceborne receivers),
+ direct building of appropriate attitude law with eclipses for all GNSS satellite types, nter-satellites
+ view detector, measurement generation feature, possibility fo use Marshall Solar Activity Future Estimation
+ to feed NRL MSISE 2000 atmosphere model, new tropospheric models: Mendes-Pavlis, Vienna 1, Vienna 3, estimated model,
+ new mapping functions for tropospheric effect: Global Mapping Function, Niell Mapping Function, Global
+ Pression Temperature Models GPT and GPT2, possibility to estimate tropospheric zenith delay,
+ clock offset that can be estimated (both for ground station and satellite clocks).">
+ <action dev="luc" type="add" issue="516">
+ Added a way to manage clock corrections from GPSPropagator.
+ </action>
<action dev="bryan" type="add" issue="498">
Added several tropospheric models: Mendes-Pavlis, Vienna 1, Vienna 3, estimated model
where the total zenith delay can be estimated during Orbit Determination.
diff --git a/src/test/java/org/orekit/propagation/analytical/gnss/GPSOrbitalElementsTest.java b/src/test/java/org/orekit/propagation/analytical/gnss/GPSOrbitalElementsTest.java
new file mode 100644
index 000000000..cd76abfaf
--- /dev/null
+++ b/src/test/java/org/orekit/propagation/analytical/gnss/GPSOrbitalElementsTest.java
@@ -0,0 +1,60 @@
+/* Copyright 2002-2019 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.analytical.gnss;
+
+
+import org.hipparchus.util.Precision;
+import org.junit.Assert;
+import org.junit.Test;
+import org.orekit.time.AbsoluteDate;
+
+public class GPSOrbitalElementsTest {
+
+ @Test
+ public void testDefaultMethods() {
+ GPSOrbitalElements goe = new GPSOrbitalElements() {
+ public AbsoluteDate getDate() { return null; }
+ public int getWeek() { return 0; }
+ public double getTime() { return 0; }
+ public double getSma() { return 0; }
+ public double getPa() { return 0; }
+ public int getPRN() { return 0; }
+ public double getOmegaDot() { return 0; }
+ public double getOmega0() { return 0; }
+ public double getMeanMotion() { return 0; }
+ public double getM0() { return 0; }
+ public double getIDot() { return 0; }
+ public double getI0() { return 0; }
+ public double getE() { return 0; }
+ public double getCus() { return 0; }
+ public double getCuc() { return 0; }
+ public double getCrs() { return 0; }
+ public double getCrc() { return 0; }
+ public double getCis() { return 0; }
+ public double getCic() { return 0; }
+ };
+ Assert.assertEquals(0, goe.getIODC());
+ Assert.assertEquals(0, goe.getIODE());
+ Assert.assertEquals(0.0, goe.getAf0(), Precision.SAFE_MIN);
+ Assert.assertEquals(0.0, goe.getAf1(), Precision.SAFE_MIN);
+ Assert.assertEquals(0.0, goe.getAf2(), Precision.SAFE_MIN);
+ Assert.assertEquals(0.0, goe.getToc(), Precision.SAFE_MIN);
+ Assert.assertEquals(0.0, goe.getTGD(), Precision.SAFE_MIN);
+
+ }
+
+}
diff --git a/src/test/java/org/orekit/propagation/analytical/gnss/GPSPropagatorTest.java b/src/test/java/org/orekit/propagation/analytical/gnss/GPSPropagatorTest.java
index 626fe9af1..bfdf3db6c 100644
--- a/src/test/java/org/orekit/propagation/analytical/gnss/GPSPropagatorTest.java
+++ b/src/test/java/org/orekit/propagation/analytical/gnss/GPSPropagatorTest.java
@@ -23,6 +23,7 @@ import java.util.Map;
import org.hipparchus.geometry.euclidean.threed.Vector3D;
import org.hipparchus.util.FastMath;
+import org.hipparchus.util.Precision;
import org.junit.Assert;
import org.junit.BeforeClass;
import org.junit.Test;
@@ -31,6 +32,7 @@ import org.orekit.frames.Frame;
import org.orekit.frames.FramesFactory;
import org.orekit.gnss.GPSAlmanac;
import org.orekit.gnss.SEMParser;
+import org.orekit.propagation.SpacecraftState;
import org.orekit.propagation.analytical.tle.TLE;
import org.orekit.propagation.analytical.tle.TLEPropagator;
import org.orekit.time.AbsoluteDate;
@@ -57,6 +59,27 @@ public class GPSPropagatorTest {
almanacs = reader.getAlmanacs();
}
+ @Test
+ public void testClockCorrections() {
+ final GPSPropagator propagator = new GPSPropagator.Builder(almanacs.get(0)).build();
+ propagator.addAdditionalStateProvider(new ClockCorrectionsProvider(almanacs.get(0)));
+ // Propagate at the GPS date and one GPS cycle later
+ final AbsoluteDate date0 = almanacs.get(0).getDate();
+ double dtRelMin = 0;
+ double dtRelMax = 0;
+ for (double dt = 0; dt < 0.5 * Constants.JULIAN_DAY; dt += 1.0) {
+ SpacecraftState state = propagator.propagate(date0.shiftedBy(dt));
+ double[] corrections = state.getAdditionalState(ClockCorrectionsProvider.CLOCK_CORRECTIONS);
+ Assert.assertEquals(3, corrections.length);
+ Assert.assertEquals(1.33514404296875E-05, corrections[0], 1.0e-19);
+ dtRelMin = FastMath.min(dtRelMin, corrections[1]);
+ dtRelMax = FastMath.max(dtRelMax, corrections[1]);
+ Assert.assertEquals(0.0, corrections[2], Precision.SAFE_MIN);
+ }
+ Assert.assertEquals(-1.1679e-8, dtRelMin, 1.0e-12);
+ Assert.assertEquals(+1.1679e-8, dtRelMax, 1.0e-12);
+ }
+
@Test
public void testGPSCycle() {
// Builds the GPSPropagator from the almanac
--
GitLab