KlobucharIonoCoefficientsLoader.java

  1. /* Copyright 2002-2025 CS GROUP
  2.  * Licensed to CS GROUP (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.  */

  18. package org.orekit.models.earth.ionosphere;

  20. import java.io.BufferedReader;
  21. import java.io.IOException;
  22. import java.io.InputStream;
  23. import java.io.InputStreamReader;
  24. import java.nio.charset.StandardCharsets;
  25. import java.text.ParseException;
  26. import java.util.Locale;
  27. import java.util.regex.Pattern;

  29. import org.orekit.annotation.DefaultDataContext;
  30. import org.orekit.data.AbstractSelfFeedingLoader;
  31. import org.orekit.data.DataContext;
  32. import org.orekit.data.DataLoader;
  33. import org.orekit.data.DataProvidersManager;
  34. import org.orekit.errors.OrekitException;
  35. import org.orekit.errors.OrekitMessages;
  36. import org.orekit.time.DateComponents;

  38. /** Loads Klobuchar-Style ionospheric coefficients a given input stream.
  39.  * A stream contains the alphas and betas coefficient for a given day.
  40.  * <p>
  41.  * They are obtained from <a href="ftp://ftp.aiub.unibe.ch/CODE/">University of Bern Astronomical Institute ftp</a>.
  42.  * Find more on the files at the <a href="http://www.aiub.unibe.ch/research/code___analysis_center/klobuchar_style_ionospheric_coefficients/index_eng.html">Astronomical Institute site</a>.
  43.  * <p>
  44.  * The files are UNIX-style compressed (.Z) files.
  45.  * They have to be extracted to UTF-8 text files before being read by this loader.
  46.  * <p>
  47.  * After extraction, it is assumed they are named CGIMDDD0.YYN where DDD and YY substitute day of year and 2-digits year.
  48.  * <p>
  49.  * The format is always the same, with and example shown below. Only the last 2 lines contains the Klobuchar coefficients.
  50.  * <p>
  51.  * Example:
  52.  * </p>
  53.  * <pre>
  54.  *      2              NAVIGATION DATA     GPS                 RINEX VERSION / TYPE
  55.  * INXFIT V5.3         AIUB                06-JAN-17 09:12     PGM / RUN BY / DATE
  56.  * CODE'S KLOBUCHAR-STYLE IONOSPHERE MODEL FOR DAY 001, 2017   COMMENT
  57.  * Contact address: code(at)aiub.unibe.ch                      COMMENT
  58.  * Data archive:    ftp.unibe.ch/aiub/CODE/                    COMMENT
  59.  *                  www.aiub.unibe.ch/download/CODE/           COMMENT
  60.  * WARNING: USE DATA AT SOUTHERN POLAR REGION WITH CARE        COMMENT
  61.  *     1.2821D-08 -9.6222D-09 -3.5982D-07 -6.0901D-07          ION ALPHA
  62.  *     1.0840D+05 -1.3197D+05 -2.6331D+05  4.0570D+05          ION BETA
  63.  *                                                             END OF HEADER
  64.  * </pre>
  65.  *
  66.  * <p>It is not safe for multiple threads to share a single instance of this class.
  67.  *
  68.  * @author Maxime Journot
  69.  */
  70. public class KlobucharIonoCoefficientsLoader extends AbstractSelfFeedingLoader
  71.         implements DataLoader {

  73.     /** Default supported files name pattern. */
  74.     public static final String DEFAULT_SUPPORTED_NAMES = "CGIM*0\\.*N$";

  76.     /** Pattern for delimiting regular expressions. */
  77.     private static final Pattern SEPARATOR = Pattern.compile("\\s+");

  79.     /** The alpha coefficients loaded. */
  80.     private double[] alpha;

  82.     /** The beta coefficients loaded. */
  83.     private double[] beta;

  85.     /**
  86.      * Constructor with supported names given by user. This constructor uses the {@link
  87.      * DataContext#getDefault() default data context}.
  88.      *
  89.      * @param supportedNames regular expression that matches the names of the RINEX files
  90.      *                       with Klobuchar coefficients.
  91.      * @see #KlobucharIonoCoefficientsLoader(String, DataProvidersManager)
  92.      */
  93.     @DefaultDataContext
  94.     public KlobucharIonoCoefficientsLoader(final String supportedNames) {
  95.         this(supportedNames, DataContext.getDefault().getDataProvidersManager());
  96.     }

  98.     /**
  99.      * Constructor that uses user defined supported names and data context.
  100.      *
  101.      * @param supportedNames       regular expression that matches the names of the RINEX
  102.      *                             files with Klobuchar coefficients.
  103.      * @param dataProvidersManager provides access to auxiliary data files.
  104.      */
  105.     public KlobucharIonoCoefficientsLoader(final String supportedNames,
  106.                                            final DataProvidersManager dataProvidersManager) {
  107.         super(supportedNames, dataProvidersManager);
  108.         this.alpha = null;
  109.         this.beta = null;
  110.     }

  112.     /**
  113.      * Constructor with default supported names. This constructor uses the {@link
  114.      * DataContext#getDefault() default data context}.
  115.      *
  116.      * @see #KlobucharIonoCoefficientsLoader(String, DataProvidersManager)
  117.      * @see #KlobucharIonoCoefficientsLoader(String)
  118.      */
  119.     @DefaultDataContext
  120.     public KlobucharIonoCoefficientsLoader() {
  121.         this(DEFAULT_SUPPORTED_NAMES);
  122.     }

  124.     /** Returns the alpha coefficients array.
  125.      * @return the alpha coefficients array
  126.      */
  127.     public double[] getAlpha() {
  128.         return alpha.clone();
  129.     }

  131.     /** Returns the beta coefficients array.
  132.      * @return the beta coefficients array
  133.      */
  134.     public double[] getBeta() {
  135.         return beta.clone();
  136.     }

  138.     @Override
  139.     public String getSupportedNames() {
  140.         return super.getSupportedNames();
  141.     }

  143.     /** Load the data using supported names .
  144.      */
  145.     public void loadKlobucharIonosphericCoefficients() {
  146.         feed(this);

  148.         // Throw an exception if alphas or betas were not loaded properly
  149.         if (alpha == null || beta == null) {
  150.             throw new OrekitException(OrekitMessages.KLOBUCHAR_ALPHA_BETA_NOT_LOADED,
  151.                     getSupportedNames());
  152.         }
  153.     }

  155.     /** Load the data for a given day.
  156.      * @param dateComponents day given but its DateComponents
  157.      */
  158.     public void loadKlobucharIonosphericCoefficients(final DateComponents dateComponents) {

  160.         // The files are named CGIMDDD0.YYN where DDD and YY substitute day of year and 2-digits year
  161.         final int    doy        = dateComponents.getDayOfYear();
  162.         final String yearString = String.valueOf(dateComponents.getYear());

  164.         this.setSupportedNames(String.format(Locale.US, "CGIM%03d0.%2sN",
  165.                                              doy, yearString.substring(yearString.length() - 2)));

  167.         try {
  168.             this.loadKlobucharIonosphericCoefficients();
  169.         } catch (OrekitException oe) {
  170.             throw new OrekitException(oe,
  171.                                       OrekitMessages.KLOBUCHAR_ALPHA_BETA_NOT_AVAILABLE_FOR_DATE,
  172.                                       dateComponents.toString());
  173.         }
  174.     }

  176.     /** {@inheritDoc} */
  177.     public boolean stillAcceptsData() {
  178.         return true;
  179.     }

  181.     /** Load Klobuchar-Style ionospheric coefficients read from some file.
  182.      * @param input data input stream
  183.      * @param name name of the file (or zip entry)
  184.      * @exception IOException if data can't be read
  185.      * @exception ParseException if data can't be parsed
  186.      */
  187.     public void loadData(final InputStream input, final String name)
  188.         throws IOException, ParseException {

  190.         int lineNumber = 0;
  191.         String line = null;
  192.         // Open stream and parse data
  193.         try (BufferedReader br = new BufferedReader(new InputStreamReader(input, StandardCharsets.UTF_8))) {

  195.             for (line = br.readLine(); line != null; line = br.readLine()) {
  196.                 ++lineNumber;
  197.                 line = line.trim();

  199.                 // Read alphas
  200.                 if (line.length() > 0 && line.endsWith("ALPHA")) {
  201.                     final String[] alpha_line = SEPARATOR.split(line);
  202.                     alpha = new double[4];
  203.                     for (int j = 0; j < 4; j++) {
  204.                         alpha[j] = Double.parseDouble(alpha_line[j].replace("D", "E"));
  205.                     }
  206.                 }

  208.                 // Read betas
  209.                 if (line.length() > 0 && line.endsWith("BETA")) {
  210.                     final String[] beta_line = SEPARATOR.split(line);
  211.                     beta = new double[4];
  212.                     for (int j = 0; j < 4; j++) {
  213.                         beta[j] = Double.parseDouble(beta_line[j].replace("D", "E"));
  214.                     }
  215.                 }
  216.             }

  218.         } catch (NumberFormatException nfe) {
  219.             throw new OrekitException(OrekitMessages.UNABLE_TO_PARSE_LINE_IN_FILE,
  220.                                       lineNumber, name, line);
  221.         }

  223.         // Check that alphas and betas were found
  224.         if (alpha == null || beta == null) {
  225.             throw new OrekitException(OrekitMessages.NO_KLOBUCHAR_ALPHA_BETA_IN_FILE, name);
  226.         }

  228.     }
  229. }
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