4
* A skeleton main() function to demonstrate the use of
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* the SGP4() and SDP4() in the sgp4sdp4.c file.
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* The TLE set to be used is read from the file amateur.txt
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* downloaded from Dr Kelso's website at www.celestrak.com.
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* Please note that this is a simple application and can only
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* read the first TLE kep set, including line 0 with the Name.
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char tle_file[] = "./amateur.txt";
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/* Observer's geodetic co-ordinates. */
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/* Lat North, Lon East in rads, Alt in km */
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geodetic_t obs_geodetic = {0.6056, 0.5761, 0.15, 0.0};
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/* Two-line Orbital Elements for the satellite */
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/* Zero vector for initializations */
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vector_t zero_vector = {0,0,0,0};
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/* Satellite position and velocity vectors */
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vector_t vel = zero_vector;
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vector_t pos = zero_vector;
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/* Satellite Az, El, Range, Range rate */
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/* Solar ECI position vector */
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vector_t solar_vector = zero_vector;
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/* Solar observed azi and ele vector */
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/* Calendar date and time (UTC) */
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/* Satellite's predicted geodetic position */
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geodetic_t sat_geodetic;
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tsince, /* Time since epoch (in minutes) */
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jul_epoch, /* Julian date of epoch */
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jul_utc, /* Julian UTC date */
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eclipse_depth = 0, /* Depth of satellite eclipse */
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/* Satellite's observed position, range, range rate */
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sat_azi, sat_ele, sat_range, sat_range_rate,
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/* Satellites geodetic position and velocity */
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sat_lat, sat_lon, sat_alt, sat_vel,
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/* Solar azimuth and elevation */
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/* Used for storing function return codes */
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ephem[5], /* Ephemeris in use string */
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sat_status[12], /* Satellite eclipse status */
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tle_lines[3][80]; /* Satellite name + two line element */
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/* File pointer for opening TLE source file */
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/* Open TLE file, abort on failure */
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if( (fp = fopen( tle_file, "r")) == NULL )
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printf(" File open failed - Exiting!\n");
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/* Get the first three lines */
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fgets(tle_lines[0], 80, fp);
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fgets(tle_lines[1], 80, fp);
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fgets(tle_lines[2], 80, fp);
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flg = Get_Next_Tle_Set(tle_lines, &tle);
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/* Print satellite name and TLE read status */
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printf(" %s: ", tle.sat_name);
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printf("TLE set bad - Exiting!\n");
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printf("TLE set good - Happy Tracking!\n");
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/* Printout of tle set data for tests if needed */
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/* printf("\n %s %s %i %i %i\n"
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" %14f %10f %8f %8f\n"
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" %8f %8f %9f %8f %8f %12f\n",
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tle.sat_name, tle.idesg, tle.catnr, tle.elset, tle.revnum,
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tle.epoch, tle.xndt2o, tle.xndd6o, tle.bstar,
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tle.xincl, tle.xnodeo, tle.eo, tle.omegao, tle.xmo, tle.xno);
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/** !Clear all flags! **/
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/* Before calling a different ephemeris */
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/* or changing the TLE set, flow control */
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/* flags must be cleared in main(). */
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ClearFlag(ALL_FLAGS);
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/** Select ephemeris type **/
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/* Will set or clear the DEEP_SPACE_EPHEM_FLAG */
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/* depending on the TLE parameters of the satellite. */
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/* It will also pre-process tle members for the */
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/* ephemeris functions SGP4 or SDP4 so this function */
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/* must be called each time a new tle set is used */
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select_ephemeris(&tle);
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/* Get UTC calendar and convert to Julian */
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UTC_Calendar_Now(&utc);
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jul_utc = Julian_Date(&utc);
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/* Convert satellite's epoch time to Julian */
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/* and calculate time since epoch in minutes */
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jul_epoch = Julian_Date_of_Epoch(tle.epoch);
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tsince = (jul_utc - jul_epoch) * xmnpda;
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/* Copy the ephemeris type in use to ephem string */
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if( isFlagSet(DEEP_SPACE_EPHEM_FLAG) )
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strcpy(ephem,"SDP4");
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strcpy(ephem,"SGP4");
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/* Call NORAD routines according to deep-space flag */
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if( isFlagSet(DEEP_SPACE_EPHEM_FLAG) )
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SDP4(tsince, &tle, &pos, &vel);
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SGP4(tsince, &tle, &pos, &vel);
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/* Scale position and velocity vectors to km and km/sec */
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Convert_Sat_State( &pos, &vel );
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/* Calculate velocity of satellite */
150
/** All angles in rads. Distance in km. Velocity in km/s **/
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/* Calculate satellite Azi, Ele, Range and Range-rate */
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Calculate_Obs(jul_utc, &pos, &vel, &obs_geodetic, &obs_set);
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/* Calculate satellite Lat North, Lon East and Alt. */
155
Calculate_LatLonAlt(jul_utc, &pos, &sat_geodetic);
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/* Calculate solar position and satellite eclipse depth */
158
/* Also set or clear the satellite eclipsed flag accordingly */
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Calculate_Solar_Position(jul_utc, &solar_vector);
160
Calculate_Obs(jul_utc,&solar_vector,&zero_vector,&obs_geodetic,&solar_set);
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if( Sat_Eclipsed(&pos, &solar_vector, &eclipse_depth) )
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SetFlag( SAT_ECLIPSED_FLAG );
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ClearFlag( SAT_ECLIPSED_FLAG );
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/* Copy a satellite eclipse status string in sat_status */
168
if( isFlagSet( SAT_ECLIPSED_FLAG ) )
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strcpy( sat_status, "Eclipsed" );
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strcpy( sat_status, "In Sunlight" );
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/* Convert and print satellite and solar data */
174
sat_azi = Degrees(obs_set.x);
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sat_ele = Degrees(obs_set.y);
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sat_range = obs_set.z;
177
sat_range_rate = obs_set.w;
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sat_lat = Degrees(sat_geodetic.lat);
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sat_lon = Degrees(sat_geodetic.lon);
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sat_alt = sat_geodetic.alt;
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sun_azi = Degrees(solar_set.x);
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sun_ele = Degrees(solar_set.y);
185
printf("\n Date: %02d/%02d/%04d UTC: %02d:%02d:%02d Ephemeris: %s"
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"\n Azi=%6.1f Ele=%6.1f Range=%8.1f Range Rate=%6.2f"
187
"\n Lat=%6.1f Lon=%6.1f Alt=%8.1f Vel=%8.3f"
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"\n Stellite Status: %s - Depth: %2.3f"
189
"\n Sun Azi=%6.1f Sun Ele=%6.1f\n",
190
utc.tm_mday, utc.tm_mon, utc.tm_year,
191
utc.tm_hour, utc.tm_min, utc.tm_sec, ephem,
192
sat_azi, sat_ele, sat_range, sat_range_rate,
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sat_lat, sat_lon, sat_alt, sat_vel,
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sat_status, eclipse_depth,
199
while( flg == flg ); /* This stops Compaq ccc 'unreachcode' warning! */
202
} /* End of main() */
204
/*------------------------------------------------------------------*/
added
removed
src/libsgp4sdp4/main.c
