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predict4java provides real-time satellite tracking and orbital prediction information
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/**
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
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.me.g4dpz.satellite;
import java.text.NumberFormat;
import java.util.Date;
/**
*
* @author g4dpz
*
*/
public class SatPos {
private static final String NL = "\n";
private static final String DEG_CR = " deg.\n";
/* WGS 84 Earth radius km */
private static final double EARTH_RADIUS = 6.378137E3;
private static final double R0 = 6378.16;
// the internal representation will be in radians
private double azimuth;
private double elevation;
private double latitude;
private double longitude;
private Date time;
private double range;
private double rangeRate;
private double phase;
private double altitude;
private double theta;
private double eclipseDepth;
private boolean eclipsed;
private boolean aboveHorizon;
/**
* Default constructor.
*/
public SatPos() {
}
/**
* Constructs a Satellite Position.
*
* @param azimuth the Azimuth
* @param elevation the Elevation
* @param theTime the Time
*/
public SatPos(final double azimuth, final double elevation, final Date theTime) {
this.azimuth = azimuth;
this.elevation = elevation;
this.time = new Date();
this.time.setTime(theTime.getTime());
}
/**
* @return the azimuth
*/
public double getAzimuth() {
return azimuth;
}
/**
* @return the elevation
*/
public double getElevation() {
return elevation;
}
/**
* @return time for the SatPos
*/
public Date getTime() {
return new Date(time.getTime());
}
/**
* @return the range
*/
public final double getRange() {
return range;
}
/**
* @param range the range to set
*/
public final void setRange(final double range) {
this.range = range;
}
/**
* @return the rangeRate
*/
public final double getRangeRate() {
return rangeRate;
}
/**
* @param rangeRate the rangeRate to set
*/
public final void setRangeRate(final double rangeRate) {
this.rangeRate = rangeRate;
}
/**
* @return the phase
*/
public final double getPhase() {
return phase;
}
/**
* @param phase the phase to set
*/
public final void setPhase(final double phase) {
this.phase = phase;
}
/**
* @return the latitude
*/
public final double getLatitude() {
return latitude;
}
/**
* @param latitude the latitude to set
*/
public final void setLatitude(final double latitude) {
this.latitude = latitude;
}
/**
* @return the longitude
*/
public final double getLongitude() {
return longitude;
}
/**
* @param longitude the longitude to set
*/
public final void setLongitude(final double longitude) {
this.longitude = longitude;
}
/**
* @return the altitude
*/
public final double getAltitude() {
return altitude;
}
/**
* @param altitude the altitude to set
*/
public final void setAltitude(final double altitude) {
this.altitude = altitude;
}
/**
* @return the theta
*/
public final double getTheta() {
return theta;
}
/**
* @param theta the theta to set
*/
public final void setTheta(final double theta) {
this.theta = theta;
}
/**
* @param azimuth the azimuth to set
*/
public final void setAzimuth(final double azimuth) {
this.azimuth = azimuth;
}
/**
* @param elevation the elevation to set
*/
public final void setElevation(final double elevation) {
this.elevation = elevation;
}
/**
* @param time the time to set
*/
public final void setTime(final Date time) {
this.time = new Date(time.getTime());
}
/**
* @return the aboveHorizon
*/
public final boolean isAboveHorizon() {
return aboveHorizon;
}
/**
* @param aboveHorizon the aboveHorizon to set
*/
public final void setAboveHorizon(final boolean aboveHorizon) {
this.aboveHorizon = aboveHorizon;
}
/**
* @return the eclipseDepth
*/
protected final double getEclipseDepth() {
return eclipseDepth;
}
/**
* @param eclipseDepth the eclipseDepth to set
*/
protected final void setEclipseDepth(final double eclipseDepth) {
this.eclipseDepth = eclipseDepth;
}
/**
* @return the eclipsed
*/
protected final boolean isEclipsed() {
return eclipsed;
}
/**
* @param eclipsed the eclipsed to set
*/
protected final void setEclipsed(final boolean eclipsed) {
this.eclipsed = eclipsed;
}
/**
* @return a pretty printed version of the Satellite Position
*/
@Override
public String toString() {
return "Azimuth: " + azimuth / (Math.PI * 2.0) * 360 + DEG_CR
+ "Elevation: " + elevation / (Math.PI * 2.0) * 360 + DEG_CR
+ "Latitude: " + latitude / (Math.PI * 2.0) * 360 + DEG_CR
+ "Longitude: " + longitude / (Math.PI * 2.0) * 360 + DEG_CR
+ "Date: " + time + NL
+ "Range: " + range + " km.\n"
+ "Range rate: " + rangeRate + " m/S.\n"
+ "Phase: " + phase + " /(256)\n"
+ "Altitude: " + altitude + " km\n"
+ "Theta: " + theta + " rad/sec\n"
+ "Eclipsed: " + eclipsed + NL
+ "Eclipse depth:" + eclipseDepth + " radians\n";
}
public String toShortString() {
String returnString = "";
final NumberFormat numberFormat = NumberFormat.getNumberInstance();
numberFormat.setMaximumFractionDigits(0);
returnString = returnString
+ "Elevation: " + numberFormat.format(elevation / (Math.PI * 2.0) * 360) + DEG_CR
+ "Azimuth: " + numberFormat.format(azimuth / (Math.PI * 2.0) * 360) + DEG_CR;
numberFormat.setMaximumFractionDigits(2);
returnString = returnString
+ "Latitude: " + numberFormat.format(latitude / (Math.PI * 2.0) * 360) + DEG_CR
+ "Longitude: " + numberFormat.format(longitude / (Math.PI * 2.0) * 360) + DEG_CR;
numberFormat.setMaximumFractionDigits(0);
returnString = returnString
+ "Range: " + numberFormat.format(range) + " Km";
return returnString;
}
public void copy(final SatPos other) {
aboveHorizon = other.aboveHorizon;
altitude = other.altitude;
azimuth = other.azimuth;
elevation = other.elevation;
latitude = other.latitude;
longitude = other.longitude;
phase = other.phase;
range = other.range;
rangeRate = other.rangeRate;
theta = other.theta;
time = other.time;
eclipseDepth = other.eclipseDepth;
eclipsed = other.eclipsed;
}
/*
* Gets the range circle as an array of integers representing pairs of latitude and longitude.
*/
public final double[][] getRangeCircle() {
return calculateRangeCirclePoints(this);
}
/**
* Calculates the footprint range circle.
*
* @param pos
* @return double array of lat/long
*/
private static double[][] calculateRangeCirclePoints(final SatPos pos) {
final int dia = (int)(12756.33 * Math.acos(EARTH_RADIUS / (EARTH_RADIUS + pos.altitude)));
final double latitude = pos.latitude;
final double longitude = pos.longitude;
final double beta = (0.5 * dia) / R0;
final double[][] result = new double[360][2];
for (int azi = 0; azi < 360; azi++) {
final double azimuth = (double)(azi / 360.0) * 2.0 * Math.PI;
double rangelat = Math.asin(Math.sin(latitude) * Math.cos(beta) + Math.cos(azimuth) * Math.sin(beta)
* Math.cos(latitude));
final double num = Math.cos(beta) - (Math.sin(latitude) * Math.sin(rangelat));
final double den = Math.cos(latitude) * Math.cos(rangelat);
double rangelong;
if (azi == 0 && (beta > ((Math.PI / 2.0) - latitude))) {
rangelong = longitude + Math.PI;
}
else if (azi == 180 && (beta > ((Math.PI / 2.0) - latitude))) {
rangelong = longitude + Math.PI;
}
else if (Math.abs(num / den) > 1.0) {
rangelong = longitude;
}
else {
if ((180 - azi) >= 0) {
rangelong = longitude - Math.acos(num / den);
}
else {
rangelong = longitude + Math.acos(num / den);
}
}
while (rangelong < 0.0) {
rangelong += Math.PI * 2.0;
}
while (rangelong > Math.PI * 2.0) {
rangelong -= Math.PI * 2.0;
}
rangelat = (rangelat / (2.0 * Math.PI)) * 360.0;
rangelong = (rangelong / (2.0 * Math.PI)) * 360.0;
// if (rangelong < 180.0) {
// rangelong = -rangelong;
// }
// else if (rangelong > 180.0) {
// rangelong = 360.0 - rangelong;
// }
//
// if (rangelat < 90.0) {
// rangelat = -rangelat;
// }
// else if (rangelat > 90.0) {
// rangelat = 180.0 - rangelat;
// }
result[azi][0] = rangelat;
result[azi][1] = rangelong;
}
return result;
}
}
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