Java tutorial
/** predict4java: An SDP4 / SGP4 library for satellite orbit predictions Copyright (C) 2004-2010 David A. B. Johnson, G4DPZ. This class is a Java port of one of the core elements of the Predict program, Copyright John A. Magliacane, KD2BD 1991-2003: http://www.qsl.net/kd2bd/predict.html Dr. T.S. Kelso is the author of the SGP4/SDP4 orbital models, originally written in Fortran and Pascal, and released into the public domain through his website (http://www.celestrak.com/). Neoklis Kyriazis, 5B4AZ, later re-wrote Dr. Kelso's code in C, and released it under the GNU GPL in 2002. PREDICT's core is based on 5B4AZ's code translation efforts. Author: David A. B. Johnson, G4DPZ <dave@g4dpz.me.uk> Comments, questions and bugreports should be submitted via http://sourceforge.net/projects/websat/ More details can be found at the project home page: http://websat.sourceforge.net This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, visit http://www.fsf.org/ */ package uk.org.funcube.fcdw.satellite; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.Serializable; import java.util.ArrayList; import java.util.Date; import java.util.List; import org.apache.commons.lang3.StringUtils; /** * TLE representation to aid SGP4 calculations. */ public class TLE implements Serializable { private static final long serialVersionUID = 716922882884628016L; private static final int THREELINES = 3; private static final double DEG2RAD = 1.745329251994330E-2; private static final double TWO_PI = Math.PI * 2.0; private static final double MINS_PERDAY = 1.44E3; private static final double XKE = 7.43669161E-2; private static final double TWO_THIRDS = 2.0 / 3.0; private static final double CK2 = 5.413079E-4; private long catnum; private String name; private int setnum; private int year; private double refepoch; private double incl; private double raan; private double eccn; private double argper; private double meanan; private double meanmo; private double drag; private double nddot6; private double bstar; private long orbitnum; private double epoch; private double xndt2o; private double xincl; private double xnodeo; private double eo; private double omegao; private double xmo; private double xno; private boolean deepspace; private java.util.Date createddate; // Constructors /** * Copy constructor. * * @param tle */ public TLE(final TLE tle) { this.catnum = tle.catnum; this.name = tle.name; this.setnum = tle.setnum; this.year = tle.year; this.refepoch = tle.refepoch; this.incl = tle.incl; this.raan = tle.raan; this.eccn = tle.eccn; this.argper = tle.argper; this.meanan = tle.meanan; this.meanmo = tle.meanmo; this.drag = tle.drag; this.nddot6 = tle.nddot6; this.bstar = tle.bstar; this.orbitnum = tle.orbitnum; this.epoch = tle.epoch; this.xndt2o = tle.xndt2o; this.xincl = tle.xincl; this.xnodeo = tle.xnodeo; this.eo = tle.eo; this.omegao = tle.omegao; this.xmo = tle.xmo; this.xno = tle.xno; this.deepspace = tle.deepspace; this.createddate = tle.createddate; } /** * @param catnum * @param name * @param setnum * @param year * @param refepoch * @param incl * @param raan * @param eccn * @param argper * @param meanan * @param meanmo * @param drag * @param nddot6 * @param bstar * @param orbitnum * @param epoch * @param xndt2o * @param xincl * @param xnodeo * @param eo * @param omegao * @param xmo * @param xno * @param deepspace * @param createddate */ public TLE(long catnum, String name, int setnum, int year, double refepoch, double incl, double raan, double eccn, double argper, double meanan, double meanmo, double drag, double nddot6, double bstar, long orbitnum, double epoch, double xndt2o, double xincl, double xnodeo, double eo, double omegao, double xmo, double xno, boolean deepspace, Date createddate) { super(); this.catnum = catnum; this.name = name; this.setnum = setnum; this.year = year; this.refepoch = refepoch; this.incl = incl; this.raan = raan; this.eccn = eccn; this.argper = argper; this.meanan = meanan; this.meanmo = meanmo; this.drag = drag; this.nddot6 = nddot6; this.bstar = bstar; this.orbitnum = orbitnum; this.epoch = epoch; this.xndt2o = xndt2o; this.xincl = xincl; this.xnodeo = xnodeo; this.eo = eo; this.omegao = omegao; this.xmo = xmo; this.xno = xno; this.deepspace = deepspace; this.createddate = createddate; } /** * Constructor. * * @param tle the three line elements * @throws IllegalArgumentException here was something wrong with the TLE */ public TLE(final String[] tle) throws IllegalArgumentException { if (null == tle) { throw new IllegalArgumentException("TLE was null"); } if (tle.length != THREELINES) { throw new IllegalArgumentException("TLE had " + tle.length + " elements"); } int lineCount = 0; for (final String line : tle) { testArguments(lineCount, line); lineCount++; } catnum = Integer.parseInt(StringUtils.strip(tle[1].substring(2, 7))); name = tle[0].trim(); setnum = Integer.parseInt(StringUtils.strip(tle[1].substring(64, 68))); year = Integer.parseInt(StringUtils.strip(tle[1].substring(18, 20))); refepoch = Double.parseDouble(tle[1].substring(20, 32)); incl = Double.parseDouble(tle[2].substring(8, 16)); raan = Double.parseDouble(tle[2].substring(17, 25)); eccn = 1.0e-07 * Double.parseDouble(tle[2].substring(26, 33)); argper = Double.parseDouble(tle[2].substring(34, 42)); meanan = Double.parseDouble(tle[2].substring(43, 51)); meanmo = Double.parseDouble(tle[2].substring(52, 63)); drag = Double.parseDouble(tle[1].substring(33, 43)); double tempnum = 1.0e-5 * Double.parseDouble(tle[1].substring(44, 50)); nddot6 = tempnum / Math.pow(10.0, Double.parseDouble(tle[1].substring(51, 52))); tempnum = 1.0e-5 * Double.parseDouble(tle[1].substring(53, 59)); bstar = tempnum / Math.pow(10.0, Double.parseDouble(tle[1].substring(60, 61))); orbitnum = Integer.parseInt(StringUtils.strip(tle[2].substring(63, 68))); /* reassign the values to thse which get used in calculations */ epoch = (1000.0 * getYear()) + getRefepoch(); xndt2o = drag; double temp = incl; temp *= DEG2RAD; xincl = temp; temp = raan; temp *= DEG2RAD; xnodeo = temp; eo = eccn; temp = argper; temp *= DEG2RAD; omegao = temp; temp = meanan; temp *= DEG2RAD; xmo = temp; xno = meanmo; /* Preprocess tle set */ preProcessTLESet(); } /** * */ private synchronized void preProcessTLESet() { double temp; temp = TWO_PI / MINS_PERDAY / MINS_PERDAY; xno = xno * temp * MINS_PERDAY; xndt2o *= temp; double dd1 = XKE / xno; final double a1 = Math.pow(dd1, TWO_THIRDS); final double r1 = Math.cos(xincl); dd1 = 1.0 - eo * eo; temp = CK2 * 1.5f * (r1 * r1 * 3.0 - 1.0) / Math.pow(dd1, 1.5); final double del1 = temp / (a1 * a1); final double ao = a1 * (1.0 - del1 * (TWO_THIRDS * .5 + del1 * (del1 * 1.654320987654321 + 1.0))); final double delo = temp / (ao * ao); final double xnodp = xno / (delo + 1.0); /* Select a deep-space/near-earth ephemeris */ deepspace = TWO_PI / xnodp / MINS_PERDAY >= 0.15625; } /** * @param lineCount the current line * @param line the line under test * @throws IllegalArgumentException there was a problem with the data */ private void testArguments(final int lineCount, final String line) throws IllegalArgumentException { if (null == line) { throw new IllegalArgumentException(createIllegalArgumentMessage(lineCount, "was null")); } if (0 == line.length()) { throw new IllegalArgumentException(createIllegalArgumentMessage(lineCount, "was zero length")); } } /** * Default constructor cannot be invoked. */ @SuppressWarnings("unused") private TLE() { } /** * @return the catalog number */ public long getCatnum() { return this.catnum; } /** * @return the name */ public String getName() { return this.name; } /** * @return the element set number */ public int getSetnum() { return this.setnum; } /** * @return the year part of the date of the elements */ public int getYear() { return this.year; } /** * @return the reference epoch of the elements */ public double getRefepoch() { return this.refepoch; } /** * @return the inclination of the satellite orbit */ public double getIncl() { return this.incl; } /** * @return the Right Ascention of the Acending Node of the orbit */ public double getRaan() { return this.raan; } /** * @return the Eccentricity of the orbit */ public double getEccn() { return this.eccn; } /** * @return the Argument of Perigee of the orbit */ public double getArgper() { return this.argper; } /** * @return the Mean Anomoly of the orbit */ public double getMeanan() { return this.meanan; } /** * @return the Mean Motion of the satellite */ public double getMeanmo() { return this.meanmo; } /** * @return the Drag factor */ public double getDrag() { return this.drag; } /** * @return Nddot6 */ public double getNddot6() { return this.nddot6; } /** * @return Bstar */ public double getBstar() { return this.bstar; } /** * @return Orbitnum */ public long getOrbitnum() { return this.orbitnum; } /** * @return Deepspace */ public boolean isDeepspace() { return deepspace; } /** * @return Eo */ public double getEo() { return eo; } /** * @return Epoch */ public double getEpoch() { return epoch; } /** * @return Omegao */ public double getOmegao() { return omegao; } /** * @return Xincl */ public double getXincl() { return xincl; } /** * @return Xmo */ public double getXmo() { return xmo; } /** * @return Xndt2o */ public synchronized double getXndt2o() { return xndt2o; } /** * @return Xno */ public synchronized double getXno() { return xno; } /** * @return Xnodeo */ public double getXnodeo() { return xnodeo; } /** * @return the createddate */ public Date getCreateddate() { return new Date(createddate.getTime()); } /** * @param createddate the createddate to set */ public void setCreateddate(final Date createddate) { this.createddate = new Date(createddate.getTime()); } /** * @param lineCount the line count * @param problem the problem * @return the description */ private String createIllegalArgumentMessage(final int lineCount, final String problem) { return "TLE line[" + lineCount + "] " + problem; } public static List<TLE> importSat(final InputStream fileIS) throws IOException { final List<TLE> importedSats = new ArrayList<TLE>(); final BufferedReader buf = new BufferedReader(new InputStreamReader(fileIS)); String readString; int j = 0; final String[] lines = new String[3]; while ((readString = buf.readLine()) != null) { switch (j) { case 0: case 1: lines[j] = readString; j++; break; case 2: lines[j] = readString; j = 0; importedSats.add(new TLE(lines)); break; default: break; } } return importedSats; } @Override public String toString() { return name; } }