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java.lang.Object keps.Transforms
public class Transforms
The Transforms class contains methods that involve transforming vectors in the Earth Centered Inertial (ECI) coordinate frame in various ways. This encompasses a rather large range of functionality. Typically, ECI vectors serve as input while a derived set of information is returned.
Much of this code was adapted from Predict ( http://www.qsl.net/kd2bd/predict.html) written by John A. Magliacane KD2BD. Assistance was also provided by Dr. TS Kelso ( http://www.celestrak.com/) and Ciprian Sufitchi N2YO ( http://www.n2yo.com/)
Constructor Summary  

Transforms()
This constructor is merely for appearances 
Method Summary  

void 
Calculate_LatLonAlt(double time,
Vector3 pos,
Geodetic coords)
This method provides geodetic (lat, lon, alt) coordinates of an object provided its ECI position and time. 
void 
Calculate_Obs(double time,
Vector3 pos,
Vector3 vel,
Geodetic coords,
ObservationSet obs_set)
This method generates topocentric coordinates (az, el, range, range rate) when provided the ECI position, velocity of the object along with the Geodetic coordinates of the observation location at a particular time. 
void 
Calculate_Solar_Position(double time,
Vector3 solar_vector)
This method generates a solar position vector in ECI coordinates based only on time 
void 
Calculate_SolarObs(double time,
Geodetic obs_coords,
Vector3 solar_pos,
ObservationSet solar_set,
Geodetic solar_latlonalt)
This method finds the position of the sun in Geodetic coordinates and as an observation set (az, el, range). 
void 
Calculate_User_PosVel(double time,
Geodetic coords,
Vector3 obs_pos,
Vector3 obs_vel)
This method uses the geodetic position and time of interest and returns the ECI position and velocity of the observer. 
double 
Sat_Eclipsed(Vector3 pos,
Vector3 sol)
This method returns the illumination level of an object based on the current position of the sun and earth. 
Methods inherited from class java.lang.Object 

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait 
Constructor Detail 

public Transforms()
Method Detail 

public void Calculate_LatLonAlt(double time, Vector3 pos, Geodetic coords)
This method was derived from Predict
Reference: The 1992 Astronomical Almanac, page K12.
time
 double The time at which the following ECI pos Vector is relevantpos
 Vector3 ECI position vector describing the current position of
object being tracked.coords
 Geodetic This is populated with the Latitude, Longitude, and Altitude
of the object being tracked. This is the output of this method.public void Calculate_User_PosVel(double time, Geodetic coords, Vector3 obs_pos, Vector3 obs_vel)
Using this to translate GPS coordinates from an orbiting satellite or airplane would likely be a bad choice.
This method was derived from Predict
Reference: The 1992 Astronomical Almanac, page K11.
time
 double The time at which the following locations are validcoords
 Geodetic The geodetic position to be translatedobs_pos
 Vector3 The ECI position vector of the object populated by this method.obs_vel
 Vector3 The ECI velocity vector of the object populated by this method.public void Calculate_Obs(double time, Vector3 pos, Vector3 vel, Geodetic coords, ObservationSet obs_set)
Azimuth  radians
Elevation  radians
Range  kilometers
Range Rate  kilometers / second
Calculations are based on topocentric position using the WGS '72 geoid
This method was derived from Predict
time
 double The time at which the following locations are validpos
 Vector3 The ECI position vector of the object.vel
 Vector3 The ECI velocity vector of the object.coords
 Geodetic The Geodetic coordinates of the observer.obs_set
 ObservationSet This is populated with the az, el, range, and range rate
of the object from the observation location.public void Calculate_Solar_Position(double time, Vector3 solar_vector)
This method was derived from Predict
time
 double The time at which the solar position vector is validpublic void Calculate_SolarObs(double time, Geodetic obs_coords, Vector3 solar_pos, ObservationSet solar_set, Geodetic solar_latlonalt)
This method was derived from Predict
time
 double The time at which the following locations are validobs_coords
 Geodetic This is the Latitude, Longitude, and Altitude of the observer.solar_pos
 Vector3 Solar ECI position vector.solar_set
 ObservationSet This is populated with the az, el, range, and range rate
of the sun from the observation location.solar_latlonalt
 Geodetic This is populated with the Geodetic coordinates corresponding to the sun.public double Sat_Eclipsed(Vector3 pos, Vector3 sol)
Reference: http://celestrak.com/columns/v03n01/
pos
 Vector3 The current position of the object in the ECI reference frame.sol
 Vector3 The current position of the sun in the ECI reference frame.


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