Merge branch 'issue-534' into release-9.3

pom.xml

@@ -5,7 +5,7 @@
   <groupId>org.orekit</groupId>
   <artifactId>orekit</artifactId>
   <packaging>jar</packaging>
-  <version>9.3</version>
+  <version>9.3.1</version>
   <name>ORbit Extrapolation KIT</name>
   <url>http://www.orekit.org/</url>
 

src/main/java/org/orekit/frames/EOPHistory.java

@@ -590,7 +590,7 @@ public class EOPHistory implements Serializable {
     /** Get a non-modifiable view of the EOP entries.
      * @return non-modifiable view of the EOP entries
      */
-    List<EOPEntry> getEntries() {
+    public List<EOPEntry> getEntries() {
         return cache.getAll();
     }
 

src/main/java/org/orekit/time/GPSDate.java

@@ -17,9 +17,13 @@
 package org.orekit.time;
 
 import java.io.Serializable;
+import java.util.List;
+import java.util.concurrent.atomic.AtomicReference;
 
 import org.hipparchus.util.FastMath;
+import org.orekit.frames.EOPEntry;
 import org.orekit.utils.Constants;
+import org.orekit.utils.IERSConventions;
 
 /** Container for date in GPS form.
  * @author Luc Maisonobe
@@ -31,12 +35,26 @@ public class GPSDate implements Serializable, TimeStamped {
     /** Serializable UID. */
     private static final long serialVersionUID = 20180633L;
 
+    /** Duration of a week in days. */
+    private static final int WEEK_D = 7;
+
     /** Duration of a week in seconds. */
-    private static final double WEEK = 7 * Constants.JULIAN_DAY;
+    private static final double WEEK_S = WEEK_D * Constants.JULIAN_DAY;
+
+    /** Number of weeks in one rollover cycle. */
+    private static final int CYCLE_W = 1024;
+
+    /** Number of days in one rollover cycle. */
+    private static final int CYCLE_D = WEEK_D * CYCLE_W;
 
-    /** conversion factor from seconds to milliseconds. */
+    /** Conversion factor from seconds to milliseconds. */
     private static final double S_TO_MS = 1000.0;
 
+    /** Reference date for ensuring continuity across GPS week rollover.
+     * @since 9.3.1
+     */
+    private static AtomicReference<DateComponents> rolloverReference = new AtomicReference<DateComponents>(null);
+
     /** Week number since {@link AbsoluteDate#GPS_EPOCH GPS epoch}. */
     private final int weekNumber;
 
@@ -47,22 +65,52 @@ public class GPSDate implements Serializable, TimeStamped {
     private final transient AbsoluteDate date;
 
     /** Build an instance corresponding to a GPS date.
-     * <p>GPS dates are provided as a week number starting at
-     * {@link AbsoluteDate#GPS_EPOCH GPS epoch} and as a number of milliseconds
-     * since week start.</p>
-     * @param weekNumber week number since {@link AbsoluteDate#GPS_EPOCH GPS epoch}
+     * <p>
+     * GPS dates are provided as a week number starting at {@link AbsoluteDate#GPS_EPOCH GPS epoch}
+     * and as a number of milliseconds since week start.
+     * </p>
+     * <p>
+     * Many interfaces provide only the 10 lower bits of the GPS week number, just as it comes from
+     * the GPS signal. In other words they use a week number modulo 1024. In order to cope with
+     * this, when the week number is smaller than 1024, this constructor assumes a modulo operation
+     * has been performed and it will fix the week number according to the reference date set up for
+     * handling rollover (see {@link #setRolloverReference(DateComponents) setRolloverReference(reference)}).
+     * If the week number is 1024 or larger, it will be used without any correction.
+     * </p>
+     * @param weekNumber week number, either absolute or modulo 1024
      * @param milliInWeek number of milliseconds since week start
      */
     public GPSDate(final int weekNumber, final double milliInWeek) {
 
-        this.weekNumber  = weekNumber;
-        this.milliInWeek = milliInWeek;
-
         final int day = (int) FastMath.floor(milliInWeek / (Constants.JULIAN_DAY * S_TO_MS));
         final double secondsInDay = milliInWeek / S_TO_MS - day * Constants.JULIAN_DAY;
-        date = new AbsoluteDate(new DateComponents(DateComponents.GPS_EPOCH, weekNumber * 7 + day),
-                                new TimeComponents(secondsInDay),
-                                TimeScalesFactory.getGPS());
+
+        int w = weekNumber;
+        DateComponents dc = new DateComponents(DateComponents.GPS_EPOCH, weekNumber * 7 + day);
+        if (weekNumber < 1024) {
+
+            DateComponents reference = rolloverReference.get();
+            if (reference == null) {
+                // lazy setting of a default reference, using end of EOP entries
+                final UT1Scale       ut1       = TimeScalesFactory.getUT1(IERSConventions.IERS_2010, true);
+                final List<EOPEntry> eop       = ut1.getEOPHistory().getEntries();
+                final int            lastMJD   = eop.get(eop.size() - 1).getMjd();
+                reference = new DateComponents(DateComponents.MODIFIED_JULIAN_EPOCH, lastMJD);
+                rolloverReference.compareAndSet(null, reference);
+            }
+
+            // fix GPS week rollover
+            while (dc.getJ2000Day() < reference.getJ2000Day() - CYCLE_D / 2) {
+                dc = new DateComponents(dc, CYCLE_D);
+                w += CYCLE_W;
+            }
+
+        }
+
+        this.weekNumber  = w;
+        this.milliInWeek = milliInWeek;
+
+        date = new AbsoluteDate(dc, new TimeComponents(secondsInDay), TimeScalesFactory.getGPS());
 
     }
 
@@ -71,14 +119,49 @@ public class GPSDate implements Serializable, TimeStamped {
      */
     public GPSDate(final AbsoluteDate date) {
 
-        this.weekNumber  = (int) FastMath.floor(date.durationFrom(AbsoluteDate.GPS_EPOCH) / WEEK);
-        final AbsoluteDate weekStart = new AbsoluteDate(AbsoluteDate.GPS_EPOCH, WEEK * weekNumber);
+        this.weekNumber  = (int) FastMath.floor(date.durationFrom(AbsoluteDate.GPS_EPOCH) / WEEK_S);
+        final AbsoluteDate weekStart = new AbsoluteDate(AbsoluteDate.GPS_EPOCH, WEEK_S * weekNumber);
         this.milliInWeek = date.durationFrom(weekStart) * S_TO_MS;
         this.date        = date;
 
     }
 
+    /** Set a reference date for ensuring continuity across GPS week rollover.
+     * <p>
+     * Instance created using the {@link #GPSDate(int, double) GPSDate(weekNumber, milliInWeek)}
+     * constructor and with a week number between 0 and 1024 after this method has been called will
+     * fix the week number to ensure they correspond to dates between {@code reference - 512 weeks}
+     * and {@code reference + 512 weeks}.
+     * </p>
+     * <p>
+     * If this method is never called, a default reference date for rollover will be set using
+     * the date of the last known EOP entry retrieved from {@link UT1Scale#getEOPHistory() UT1}
+     * time scale.
+     * </p>
+     * @param reference reference date for GPS week rollover
+     * @see #getRolloverReference()
+     * @see #GPSDate(int, double)
+     * @since 9.3.1
+     */
+    public static void setRolloverReference(final DateComponents reference) {
+        rolloverReference.set(reference);
+    }
+
+    /** Get the reference date ensuring continuity across GPS week rollover.
+     * @return reference reference date for GPS week rollover
+     * @see #setRolloverReference(AbsoluteDate)
+     * @see #GPSDate(int, double)
+     * @since 9.3.1
+     */
+    public static DateComponents getRolloverReference() {
+        return rolloverReference.get();
+    }
+
     /** Get the week number since {@link AbsoluteDate#GPS_EPOCH GPS epoch}.
+     * <p>
+     * The week number returned here has been fixed for GPS week rollover, i.e.
+     * it may be larger than 1024.
+     * </p>
      * @return week number since {@link AbsoluteDate#GPS_EPOCH GPS epoch}
      */
     public int getWeekNumber() {

src/site/markdown/downloads.md

@@ -43,9 +43,14 @@ as required.
 
 |  package |                                              link                                                                                     |
 |----------|---------------------------------------------------------------------------------------------------------------------------------------|
-|  source  | orekit-9.3-sources.zip (URL to be defined after official release)                                                                     |
-|  binary  | orekit-9.3.jar (URL to be defined after official release)                                                                             |
-|  javadoc | orekit-9.3-javadoc.jar (URL to be defined after official release)                                                                     |
+|  source  | orekit-9.3.1-sources.zip (URL to be defined after official release)                                                                   |
+|  binary  | orekit-9.3.1.jar (URL to be defined after official release)                                                                           |
+version 9.3.1 downloads (release date: 2019-03-16)
+
+|  package |                                              link                                                                                     |
+|----------|---------------------------------------------------------------------------------------------------------------------------------------|
+|  source  | [orekit-9.3-sources.zip](https://gitlab.orekit.org/orekit/orekit/uploads/e313519415d0313043587739d417abcb/orekit-9.3-sources.zip)      |
+|  binary  | [orekit-9.3.jar](https://gitlab.orekit.org/orekit/orekit/uploads/32bc68ad2f4e58d1e8de71dbc4ff3494/orekit-9.3.jar)                      |
 version 9.3 downloads (release date: 2019-01-25)
 
 |  package |                                              link                                                                                     |

src/site/xdoc/changes.xml

@@ -20,6 +20,12 @@
     <title>Orekit Changes</title>
   </properties>
   <body>
+    <release version="9.3.1" date="2019-03-16" description="Version 9.3.1 is a minor version of Orekit.
+    It fixes an issue with GPS week rollover.">
+      <action dev="luc" type="add" issue="534">
+        Handle GPS week rollover in GPSDate.
+      </action>
+    </release>
     <release version="9.3" date="2019-01-25" 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

src/test/java/org/orekit/Utils.java

@@ -42,6 +42,7 @@ import org.orekit.propagation.semianalytical.dsst.utilities.JacobiPolynomials;
 import org.orekit.propagation.semianalytical.dsst.utilities.NewcombOperators;
 import org.orekit.time.AbsoluteDate;
 import org.orekit.time.DateComponents;
+import org.orekit.time.GPSDate;
 import org.orekit.time.TimeScale;
 import org.orekit.time.TimeScalesFactory;
 import org.orekit.utils.Constants;
@@ -85,6 +86,7 @@ public class Utils {
         FramesFactory.clearEOPHistoryLoaders();
         FramesFactory.setEOPContinuityThreshold(5 * Constants.JULIAN_DAY);
         TimeScalesFactory.clearUTCTAIOffsetsLoaders();
+        GPSDate.setRolloverReference(null);
         GravityFieldFactory.clearPotentialCoefficientsReaders();
         GravityFieldFactory.clearOceanTidesReaders();
         DataProvidersManager.getInstance().clearProviders();

src/test/java/org/orekit/propagation/analytical/gnss/GPSPropagatorTest.java

@@ -36,6 +36,7 @@ import org.orekit.propagation.SpacecraftState;
 import org.orekit.propagation.analytical.tle.TLE;
 import org.orekit.propagation.analytical.tle.TLEPropagator;
 import org.orekit.time.AbsoluteDate;
+import org.orekit.time.DateComponents;
 import org.orekit.time.GPSDate;
 import org.orekit.time.TimeScalesFactory;
 import org.orekit.utils.CartesianDerivativesFilter;
@@ -51,6 +52,7 @@ public class GPSPropagatorTest {
     @BeforeClass
     public static void setUpBeforeClass() {
         Utils.setDataRoot("gnss");
+        GPSDate.setRolloverReference(new DateComponents(DateComponents.GPS_EPOCH, 7 * 512));
         // Get the parser to read a SEM file
         SEMParser reader = new SEMParser(null);
         // Reads the SEM file

src/test/java/org/orekit/time/GPSDateTest.java

@@ -38,6 +38,7 @@ public class GPSDateTest {
         Assert.assertEquals(1387, date.getWeekNumber());
         Assert.assertEquals(318677000.0, date.getMilliInWeek(), 1.0e-15);
         Assert.assertEquals(0, date.getDate().durationFrom(ref), 1.0e-15);
+        Assert.assertNull(GPSDate.getRolloverReference());
     }
 
     @Test
@@ -56,6 +57,34 @@ public class GPSDateTest {
         Assert.assertEquals(0.0, date.getMilliInWeek(), 1.0e-15);
     }
 
+    @Test
+    public void testZeroZero() {
+        GPSDate.setRolloverReference(new DateComponents(DateComponents.GPS_EPOCH, 7 * 512));
+        GPSDate date1 = new GPSDate(0, 0.0);
+        Assert.assertEquals(0.0, date1.getDate().durationFrom(AbsoluteDate.GPS_EPOCH), 1.0e-15);
+        GPSDate.setRolloverReference(new DateComponents(GPSDate.getRolloverReference(), 1));
+        GPSDate date2 = new GPSDate(0, 0.0);
+        Assert.assertEquals(1024, date2.getWeekNumber());
+    }
+
+    @Test
+    public void testDefaultRolloverReference() {
+        Assert.assertNull(GPSDate.getRolloverReference());
+        GPSDate date = new GPSDate(305, 1.5);
+        // the default reference is extracted from last EOP entry
+        // which in this test comes from bulletin B 218, in the final values section
+        Assert.assertEquals("2006-03-05", GPSDate.getRolloverReference().toString());
+        Assert.assertEquals(305 + 1024, date.getWeekNumber());
+    }
+
+    @Test
+    public void testUserRolloverReference() {
+        GPSDate.setRolloverReference(new DateComponents(DateComponents.GPS_EPOCH, 7 * (3 * 1024 + 512)));
+        GPSDate date = new GPSDate(305, 1.5);
+        Assert.assertEquals("2048-09-13", GPSDate.getRolloverReference().toString());
+        Assert.assertEquals(305 + 3 * 1024, date.getWeekNumber());
+    }
+
     @Test
     public void testSerialization() throws IOException, ClassNotFoundException {
         GPSDate date = new GPSDate(1387, 318677000.0);