ContentsIndexReferenceHome
PreviousUpNext
Functions for Satellite Propagation
EngagementTools Functions

The functions in this section are for satellite propagation, including the Sun and moon. Some of these functions were designed specifically for use with the space-track.org satellite catalog. There is an example script using some of these functions that is installed with this toolbox in EngagementTools/Examples.

Functions
Name 
Description 
Converts the date from one time zone (TZin) to another (TZout). If TZout is empty, Universal Time is returned. Daylight saving time is handled automatically in the code - although care should be taken here as the start and end dates vary with location and date. 
Converts a epoch Gregorian date into the Julian date. The code handles date vectors and date strings supported by Matlab. 
Converts a Julian date into the epoch Gregorian date. The code handles date vectors and date strings supported by matlab. 
LOS 
Determines if there is line of site between two satellites assuming a circular earth. This algorithm should only be used for altitudes above 100 km, For altitudes below 100km, use GeomStruct or SunRiseSet. Satellite positions should be in the ECF coordinate frame. LOS can determine if an asset is sunlit by passing in the satellite ECF position vector in as r1 and the Julian date as r2. In that case r2 must have the same dimensions as r1, except for the last dimension that contain the position vector. 
Determines the lunar phase for the specified date. 
Determines the moon position, right ascension and declination, and ECF position 
Returns a geometry structure of ECF positions and velocities by propagating the input TLE set using the NORAD SGP4/SDP4 propagator. This code runs much faster when using the calling sequence with three outputs: matrices for position and velocity in ECI coordinates and time. 
SDP4 
The NORAD deep space satellite position and velocity propagator. Time samples are vectorized for quick generation, but the satellite ephemeris data is not. 
SGP4 
Implementation of the NORAD low orbit satellite position and velocity propagator. Time samples are vectorized for quick generation, but the satellite ephemeris data is not. 
Prepares extracted TLE data, such as output by TLEExtract, for use by the NORAD SGP propagators (old FORTRAN convention). It also determines which SGP model to use based on the period. In general SGP requires these units: time in minutes, distance in units of earth radii, angular quantities in radians. 
Converts the Julian date into Greenwich Mean & Local Mean Sidereal Time. Uses julian date format given in Seidelmann. Valid 1901-2199 AD. 
Uses the low precision formulas for the sun presented in section C of The Astronomical Almanac for determining the sun position, right ascension and declination. The precision is given as one minute of arc, but the solar mean anomaly, longitude, etc. use the IAU 2000 methods, increasing the precision. Valid for years 1950-2050 AD. 
Determines the sun position, right ascension and declination, equation of time, rise and set times, etc. for an given date 
Extracts the Two Line Element (TLE) data from a TLE (two or three line) data array. Since the input is a data array, the input should be a 2x69 or 3X69 string array. If the check sum error flag is triggered, a note will be made in tleMessage 
Loads TLEs from the given catalog file or the most recent data if a catalog directory is specified. Parses a TLE string array or file location into a structure of strings. It also pads any lines that fall short of the needed 69 characters and handles two and three line element sets. If no file is passed in with the location string, the code will grab the latest file that has the word "catalog" in it (after the space-track.org convention) and you may pass in a gzip file directly. SearchParam is set for either "Name" or "SatNum" and the SearchList... more 
Module
Made with Doc-O-Matic.
Copyright (c) 2009. All rights reserved.
What do you think about this topic? Send feedback!