TLESeries.java

  1. /* Copyright 2002-2013 CS Systèmes d'Information
  2.  * Licensed to CS Systèmes d'Information (CS) under one or more
  3.  * contributor license agreements.  See the NOTICE file distributed with
  4.  * this work for additional information regarding copyright ownership.
  5.  * CS licenses this file to You under the Apache License, Version 2.0
  6.  * (the "License"); you may not use this file except in compliance with
  7.  * the License.  You may obtain a copy of the License at
  8.  *
  9.  *   http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */
  17. package org.orekit.propagation.analytical.tle;

  19. import java.io.BufferedReader;
  20. import java.io.IOException;
  21. import java.io.InputStream;
  22. import java.io.InputStreamReader;
  23. import java.util.Set;
  24. import java.util.SortedSet;
  25. import java.util.TreeSet;

  27. import org.orekit.data.DataLoader;
  28. import org.orekit.data.DataProvidersManager;
  29. import org.orekit.errors.OrekitException;
  30. import org.orekit.errors.OrekitMessages;
  31. import org.orekit.time.AbsoluteDate;
  32. import org.orekit.time.ChronologicalComparator;
  33. import org.orekit.time.TimeStamped;
  34. import org.orekit.utils.PVCoordinates;

  36. /** This class reads and handles series of TLEs for one space object.
  37.  *  <p>
  38.  *  TLE data is read using the standard Orekit mechanism based on a configured
  39.  *  {@link DataProvidersManager DataProvidersManager}. This means TLE data may
  40.  *  be retrieved from many different storage media (local disk files, remote servers,
  41.  *  database ...).
  42.  *  </p>
  43.  *  <p>
  44.  *  This class provides bounded ephemerides by finding the best initial TLE to
  45.  *  propagate and then handling the propagation.
  46.  *  </p>
  47.  *
  48.  * @see TLE
  49.  * @see DataProvidersManager
  50.  * @author Fabien Maussion
  51.  * @author Luc Maisonobe
  52.  */
  53. public class TLESeries implements DataLoader {

  55.     /** Default supported files name pattern. */
  56.     private static final String DEFAULT_SUPPORTED_NAMES = ".*\\.tle$";

  58.     /** Regular expression for supported files names. */
  59.     private final String supportedNames;

  61.     /** Available satellite numbers. */
  62.     private final Set<Integer> availableSatNums;

  64.     /** Set containing all TLE entries. */
  65.     private final SortedSet<TimeStamped> tles;

  67.     /** Satellite number used for filtering. */
  68.     private int filterSatelliteNumber;

  70.     /** Launch year used for filtering (all digits). */
  71.     private int filterLaunchYear;

  73.     /** Launch number used for filtering. */
  74.     private int filterLaunchNumber;

  76.     /** Launch piece used for filtering. */
  77.     private String filterLaunchPiece;

  79.     /** Previous TLE in the cached selection. */
  80.     private TLE previous;

  82.     /** Next TLE in the cached selection. */
  83.     private TLE next;

  85.     /** Last used TLE. */
  86.     private TLE lastTLE;

  88.     /** Associated propagator. */
  89.     private TLEPropagator lastPropagator;

  91.     /** Date of the first TLE. */
  92.     private AbsoluteDate firstDate;

  94.     /** Date of the last TLE. */
  95.     private AbsoluteDate lastDate;

  97.     /** Indicator for non-TLE extra lines. */
  98.     private final boolean ignoreNonTLELines;

  100.     /** Simple constructor with a TLE file.
  101.      * <p>This constructor does not load any data by itself. Data must be
  102.      * loaded later on by calling one of the {@link #loadTLEData()
  103.      * loadTLEData()} method, the {@link #loadTLEData(int)
  104.      * loadTLEData(filterSatelliteNumber)} method or the {@link #loadTLEData(int,
  105.      * int, String) loadTLEData(filterLaunchYear, filterLaunchNumber, filterLaunchPiece)} method.<p>
  106.      * @param supportedNames regular expression for supported files names
  107.      * (if null, a default pattern matching files with a ".tle" extension will be used)
  108.      * @param ignoreNonTLELines if true, extra non-TLE lines are silently ignored,
  109.      * if false an exception will be generated when such lines are encountered
  110.      * @see #loadTLEData()
  111.      * @see #loadTLEData(int)
  112.      * @see #loadTLEData(int, int, String)
  113.      */
  114.     public TLESeries(final String supportedNames, final boolean ignoreNonTLELines) {

  116.         this.supportedNames    = (supportedNames == null) ? DEFAULT_SUPPORTED_NAMES : supportedNames;
  117.         availableSatNums       = new TreeSet<Integer>();
  118.         this.ignoreNonTLELines = ignoreNonTLELines;
  119.         filterSatelliteNumber  = -1;
  120.         filterLaunchYear       = -1;
  121.         filterLaunchNumber     = -1;
  122.         filterLaunchPiece      = null;

  124.         tles     = new TreeSet<TimeStamped>(new ChronologicalComparator());
  125.         previous = null;
  126.         next     = null;

  128.     }

  130.     /** Load TLE data for a specified object.
  131.      * <p>The TLE data already loaded in the instance will be discarded
  132.      * and replaced by the newly loaded data.</p>
  133.      * <p>The filtering values will be automatically set to the first loaded
  134.      * satellite. This feature is useful when the satellite selection is
  135.      * already set up by either the instance configuration (supported file
  136.      * names) or by the {@link DataProvidersManager data providers manager}
  137.      * configuration and the local filtering feature provided here can be ignored.</p>
  138.      * @exception OrekitException if some data can't be read, some
  139.      * file content is corrupted or no TLE data is available
  140.      * @see #loadTLEData(int)
  141.      * @see #loadTLEData(int, int, String)
  142.      */
  143.     public void loadTLEData() throws OrekitException {

  145.         availableSatNums.clear();

  147.         // set the filtering parameters
  148.         filterSatelliteNumber = -1;
  149.         filterLaunchYear      = -1;
  150.         filterLaunchNumber    = -1;
  151.         filterLaunchPiece     = null;

  153.         // load the data from the configured data providers
  154.         tles.clear();
  155.         DataProvidersManager.getInstance().feed(supportedNames, this);
  156.         if (tles.isEmpty()) {
  157.             throw new OrekitException(OrekitMessages.NO_TLE_DATA_AVAILABLE);
  158.         }

  160.     }

  162.     /** Get the available satellite numbers.
  163.      * @return available satellite numbers
  164.      * @throws OrekitException if some data can't be read, some
  165.      * file content is corrupted or no TLE data is available
  166.      */
  167.     public Set<Integer> getAvailableSatelliteNumbers() throws OrekitException {
  168.         if (availableSatNums.isEmpty()) {
  169.             loadTLEData();
  170.         }
  171.         return availableSatNums;
  172.     }

  174.     /** Load TLE data for a specified object.
  175.      * <p>The TLE data already loaded in the instance will be discarded
  176.      * and replaced by the newly loaded data.</p>
  177.      * <p>Calling this method with the satellite number set to a negative value,
  178.      * is equivalent to call {@link #loadTLEData()}.</p>
  179.      * @param satelliteNumber satellite number
  180.      * @exception OrekitException if some data can't be read, some
  181.      * file content is corrupted or no TLE data is available for the selected object
  182.      * @see #loadTLEData()
  183.      * @see #loadTLEData(int, int, String)
  184.      */
  185.     public void loadTLEData(final int satelliteNumber) throws OrekitException {

  187.         if (satelliteNumber < 0) {
  188.             // no filtering at all
  189.             loadTLEData();
  190.         } else {
  191.             // set the filtering parameters
  192.             filterSatelliteNumber = satelliteNumber;
  193.             filterLaunchYear      = -1;
  194.             filterLaunchNumber    = -1;
  195.             filterLaunchPiece     = null;

  197.             // load the data from the configured data providers
  198.             tles.clear();
  199.             DataProvidersManager.getInstance().feed(supportedNames, this);
  200.             if (tles.isEmpty()) {
  201.                 throw new OrekitException(OrekitMessages.NO_TLE_FOR_OBJECT, satelliteNumber);
  202.             }
  203.         }

  205.     }

  207.     /** Load TLE data for a specified object.
  208.      * <p>The TLE data already loaded in the instance will be discarded
  209.      * and replaced by the newly loaded data.</p>
  210.      * <p>Calling this method with either the launch year or the launch number
  211.      * set to a negative value, or the launch piece set to null or an empty
  212.      * string are all equivalent to call {@link #loadTLEData()}.</p>
  213.      * @param launchYear launch year (all digits)
  214.      * @param launchNumber launch number
  215.      * @param launchPiece launch piece
  216.      * @exception OrekitException if some data can't be read, some
  217.      * file content is corrupted or no TLE data is available for the selected object
  218.      * @see #loadTLEData()
  219.      * @see #loadTLEData(int)
  220.      */
  221.     public void loadTLEData(final int launchYear, final int launchNumber,
  222.                             final String launchPiece) throws OrekitException {

  224.         if ((launchYear < 0) || (launchNumber < 0) ||
  225.             (launchPiece == null) || (launchPiece.length() == 0)) {
  226.             // no filtering at all
  227.             loadTLEData();
  228.         } else {
  229.             // set the filtering parameters
  230.             filterSatelliteNumber = -1;
  231.             filterLaunchYear      = launchYear;
  232.             filterLaunchNumber    = launchNumber;
  233.             filterLaunchPiece     = launchPiece;

  235.             // load the data from the configured data providers
  236.             tles.clear();
  237.             DataProvidersManager.getInstance().feed(supportedNames, this);
  238.             if (tles.isEmpty()) {
  239.                 throw new OrekitException(OrekitMessages.NO_TLE_FOR_LAUNCH_YEAR_NUMBER_PIECE,
  240.                                           launchYear, launchNumber, launchPiece);
  241.             }
  242.         }

  244.     }

  246.     /** {@inheritDoc} */
  247.     public boolean stillAcceptsData() {
  248.         return tles.isEmpty();
  249.     }

  251.     /** {@inheritDoc} */
  252.     public void loadData(final InputStream input, final String name)
  253.         throws IOException, OrekitException {

  255.         final BufferedReader r = new BufferedReader(new InputStreamReader(input, "UTF-8"));
  256.         try {

  258.             int lineNumber     = 0;
  259.             String pendingLine = null;
  260.             for (String line = r.readLine(); line != null; line = r.readLine()) {

  262.                 ++lineNumber;

  264.                 if (pendingLine == null) {

  266.                     // we must wait for the second line
  267.                     pendingLine = line;

  269.                 } else {

  271.                     // safety checks
  272.                     if (!TLE.isFormatOK(pendingLine, line)) {
  273.                         if (ignoreNonTLELines) {
  274.                             // just shift one line
  275.                             pendingLine = line;
  276.                             continue;
  277.                         } else {
  278.                             throw new OrekitException(OrekitMessages.NOT_TLE_LINES,
  279.                                                       lineNumber - 1, lineNumber, pendingLine, line);
  280.                         }
  281.                     }

  283.                     final TLE tle = new TLE(pendingLine, line);

  285.                     if (filterSatelliteNumber < 0) {
  286.                         if ((filterLaunchYear < 0) ||
  287.                             ((tle.getLaunchYear()   == filterLaunchYear) &&
  288.                              (tle.getLaunchNumber() == filterLaunchNumber) &&
  289.                              tle.getLaunchPiece().equals(filterLaunchPiece))) {
  290.                             // we now know the number of the object to load
  291.                             filterSatelliteNumber = tle.getSatelliteNumber();
  292.                         }
  293.                     }

  295.                     availableSatNums.add(tle.getSatelliteNumber());

  297.                     if (tle.getSatelliteNumber() == filterSatelliteNumber) {
  298.                         // accept this TLE
  299.                         tles.add(tle);
  300.                     }

  302.                     // we need to wait for two new lines
  303.                     pendingLine = null;

  305.                 }

  307.             }

  309.             if ((pendingLine != null) && !ignoreNonTLELines) {
  310.                 // there is an unexpected last line
  311.                 throw new OrekitException(OrekitMessages.MISSING_SECOND_TLE_LINE,
  312.                                           lineNumber, pendingLine);
  313.             }

  315.         } finally {
  316.             r.close();
  317.         }

  319.     }

  321.     /** Get the extrapolated position and velocity from an initial date.
  322.      * For a good precision, this date should not be too far from the range :
  323.      * [{@link #getFirstDate() first date} ; {@link #getLastDate() last date}].
  324.      * @param date the final date
  325.      * @return the final PVCoordinates
  326.      * @exception OrekitException if the underlying propagator cannot be initialized
  327.      */
  328.     public PVCoordinates getPVCoordinates(final AbsoluteDate date)
  329.         throws OrekitException {
  330.         final TLE toExtrapolate = getClosestTLE(date);
  331.         if (toExtrapolate != lastTLE) {
  332.             lastTLE = toExtrapolate;
  333.             lastPropagator = TLEPropagator.selectExtrapolator(lastTLE);
  334.         }
  335.         return lastPropagator.getPVCoordinates(date);
  336.     }

  338.     /** Get the closest TLE to the selected date.
  339.      * @param date the date
  340.      * @return the TLE that will suit the most for propagation.
  341.      */
  342.     public TLE getClosestTLE(final AbsoluteDate date) {

  344.         //  don't search if the cached selection is fine
  345.         if ((previous != null) && (date.durationFrom(previous.getDate()) >= 0) &&
  346.             (next     != null) && (date.durationFrom(next.getDate())     <= 0)) {
  347.             // the current selection is already good
  348.             if (next.getDate().durationFrom(date) > date.durationFrom(previous.getDate())) {
  349.                 return previous;
  350.             } else {
  351.                 return next;
  352.             }
  353.         }
  354.         // reset the selection before the search phase
  355.         previous  = null;
  356.         next      = null;
  357.         final SortedSet<TimeStamped> headSet = tles.headSet(date);
  358.         final SortedSet<TimeStamped> tailSet = tles.tailSet(date);


  361.         if (headSet.isEmpty()) {
  362.             return (TLE) tailSet.first();
  363.         }
  364.         if (tailSet.isEmpty()) {
  365.             return (TLE) headSet.last();
  366.         }
  367.         previous = (TLE) headSet.last();
  368.         next = (TLE) tailSet.first();

  370.         if (next.getDate().durationFrom(date) > date.durationFrom(previous.getDate())) {
  371.             return previous;
  372.         } else {
  373.             return next;
  374.         }
  375.     }

  377.     /** Get the start date of the series.
  378.      * @return the first date
  379.      */
  380.     public AbsoluteDate getFirstDate() {
  381.         if (firstDate == null) {
  382.             firstDate = tles.first().getDate();
  383.         }
  384.         return firstDate;
  385.     }

  387.     /** Get the last date of the series.
  388.      * @return the end date
  389.      */
  390.     public AbsoluteDate getLastDate() {
  391.         if (lastDate == null) {
  392.             lastDate = tles.last().getDate();
  393.         }
  394.         return lastDate;
  395.     }

  397.     /** Get the first TLE.
  398.      * @return first TLE
  399.      */
  400.     public TLE getFirst() {
  401.         return (TLE) tles.first();
  402.     }

  404.     /** Get the last TLE.
  405.      * @return last TLE
  406.      */
  407.     public TLE getLast() {
  408.         return (TLE) tles.last();
  409.     }

  411. }
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