satellite-sgp4io.cc

Go to the documentation of this file.

/*  ----------------------------------------------------------------
 *
 *                                 sgp4io.h;
 *
 *    this file contains a function to read two line element sets. while
 *    not formerly part of the sgp4 mathematical theory, it is
 *    required for practical implemenation.
 *
 *                            companion code for
 *               fundamentals of astrodynamics and applications
 *                                    2007
 *                              by david vallado
 *
 *       (w) 719-573-2600, email dvallado@agi.com
 *
 *    current :
 *               3 sep 07  david vallado
 *                           add operationmode for afspc (a) or improved (i)
 *    changes :
 *              20 apr 07  david vallado
 *                           misc updates for manual operation
 *              14 aug 06  david vallado
 *                           original baseline
 *
 *    code from https://gitlab.inesctec.pt/pmms/ns3-satellite
 * ---------------------------------------------------------------- */
 
#include "satellite-sgp4io.h"
 
#include <stdint.h>
 
/* -----------------------------------------------------------------------------
 *
 *                           function twoline2rv
 *
 *  this function converts the two line element set character string data to
 *    variables and initializes the sgp4 variables. several intermediate varaibles
 *    and quantities are determined. note that the result is a structure so multiple
 *    satellites can be processed simultaneously without having to reinitialize. the
 *    verification mode is an important option that permits quick checks of any
 *    changes to the underlying technical theory. this option works using a
 *    modified tle file in which the start, stop, and delta time values are
 *    included at the end of the second line of data. this only works with the
 *    verification mode. the catalog mode simply propagates from -1440 to 1440 min
 *    from epoch and is useful when performing entire catalog runs.
 *
 *  author        : david vallado                  719-573-2600    1 mar 2001
 *
 *  inputs        :
 *    longstr1    - first line of the tle
 *    longstr2    - second line of the tle
 *    typerun     - type of run                    verification 'v', catalog 'c',
 *                                                 manual 'm'
 *    typeinput   - type of manual input           mfe 'm', epoch 'e', dayofyr 'd'
 *    opsmode     - mode of operation afspc or improved 'a', 'i'
 *    whichconst  - which set of constants to use  72, 84
 *
 *  outputs       :
 *    satrec      - structure containing all the sgp4 satellite information
 *
 *  coupling      :
 *    getgravconst-
 *    days2mdhms  - conversion of days to month, day, hour, minute, second
 *    jday        - convert day month year hour minute second into julian date
 *    sgp4init    - initialize the sgp4 variables
 *
 *  references    :
 *    norad spacetrack report #3
 *    vallado, crawford, hujsak, kelso  2006
 * --------------------------------------------------------------------------- */
 
void
twoline2rv(char longstr1[130],
           char longstr2[130],
           char typerun,
           char typeinput,
           char opsmode,
           gravconsttype whichconst,
           double& startmfe,
           double& stopmfe,
           double& deltamin,
           elsetrec& satrec)
{
    const double deg2rad = pi / 180.0;         //   0.0174532925199433
    const double xpdotp = 1440.0 / (2.0 * pi); // 229.1831180523293
 
    double sec, mu, radiusearthkm, tumin, xke, j2, j3, j4, j3oj2;
    double startsec, stopsec, startdayofyr, stopdayofyr, jdstart, jdstop;
    int startyear, stopyear, startmon, stopmon, startday, stopday, starthr, stophr, startmin,
        stopmin;
    int cardnumb, numb, j;
    long revnum = 0, elnum = 0;
    char classification, intldesg[11];
    int year = 0;
    int mon, day, hr, minute, nexp, ibexp;
    int silence;
 
    getgravconst(whichconst, tumin, mu, radiusearthkm, xke, j2, j3, j4, j3oj2);
 
    satrec.error = 0;
 
    // set the implied decimal points since doing a formated read
    // fixes for bad input data values (missing, ...)
    for (j = 10; j <= 15; j++)
        if (longstr1[j] == ' ')
            longstr1[j] = '_';
 
    if (longstr1[44] != ' ')
        longstr1[43] = longstr1[44];
    longstr1[44] = '.';
    if (longstr1[7] == ' ')
        longstr1[7] = 'U';
    if (longstr1[9] == ' ')
        longstr1[9] = '.';
    for (j = 45; j <= 49; j++)
        if (longstr1[j] == ' ')
            longstr1[j] = '0';
    if (longstr1[51] == ' ')
        longstr1[51] = '0';
    if (longstr1[53] != ' ')
        longstr1[52] = longstr1[53];
    longstr1[53] = '.';
    longstr2[25] = '.';
    for (j = 26; j <= 32; j++)
        if (longstr2[j] == ' ')
            longstr2[j] = '0';
    if (longstr1[62] == ' ')
        longstr1[62] = '0';
    if (longstr1[68] == ' ')
        longstr1[68] = '0';
 
    sscanf(longstr1,
           "%2d %5ld %1c %10s %2d %12lf %11lf %7lf %2d %7lf %2d %2d %6ld ",
           &cardnumb,
           &satrec.satnum,
           &classification,
           intldesg,
           &satrec.epochyr,
           &satrec.epochdays,
           &satrec.ndot,
           &satrec.nddot,
           &nexp,
           &satrec.bstar,
           &ibexp,
           &numb,
           &elnum);
 
    if (typerun == 'v') // run for specified times from the file
    {
        if (longstr2[52] == ' ')
            sscanf(longstr2,
                   "%2d %5ld %9lf %9lf %8lf %9lf %9lf %10lf %6ld %lf %lf %lf \n",
                   &cardnumb,
                   &satrec.satnum,
                   &satrec.inclo,
                   &satrec.nodeo,
                   &satrec.ecco,
                   &satrec.argpo,
                   &satrec.mo,
                   &satrec.no,
                   &revnum,
                   &startmfe,
                   &stopmfe,
                   &deltamin);
        else
            sscanf(longstr2,
                   "%2d %5ld %9lf %9lf %8lf %9lf %9lf %11lf %6ld %lf %lf %lf \n",
                   &cardnumb,
                   &satrec.satnum,
                   &satrec.inclo,
                   &satrec.nodeo,
                   &satrec.ecco,
                   &satrec.argpo,
                   &satrec.mo,
                   &satrec.no,
                   &revnum,
                   &startmfe,
                   &stopmfe,
                   &deltamin);
    }
    else // simply run -1 day to +1 day or user input times
    {
        if (longstr2[52] == ' ')
            sscanf(longstr2,
                   "%2d %5ld %9lf %9lf %8lf %9lf %9lf %10lf %6ld \n",
                   &cardnumb,
                   &satrec.satnum,
                   &satrec.inclo,
                   &satrec.nodeo,
                   &satrec.ecco,
                   &satrec.argpo,
                   &satrec.mo,
                   &satrec.no,
                   &revnum);
        else
            sscanf(longstr2,
                   "%2d %5ld %9lf %9lf %8lf %9lf %9lf %11lf %6ld \n",
                   &cardnumb,
                   &satrec.satnum,
                   &satrec.inclo,
                   &satrec.nodeo,
                   &satrec.ecco,
                   &satrec.argpo,
                   &satrec.mo,
                   &satrec.no,
                   &revnum);
    }
 
    // ---- find no, ndot, nddot ----
    satrec.no = satrec.no / xpdotp; //* rad/min
    satrec.nddot = satrec.nddot * pow(10.0, nexp);
    satrec.bstar = satrec.bstar * pow(10.0, ibexp);
 
    // ---- convert to sgp4 units ----
    satrec.a = pow(satrec.no * tumin, (-2.0 / 3.0));
    satrec.ndot = satrec.ndot / (xpdotp * 1440.0); //* ? * minperday
    satrec.nddot = satrec.nddot / (xpdotp * 1440.0 * 1440);
 
    // ---- find standard orbital elements ----
    satrec.inclo = satrec.inclo * deg2rad;
    satrec.nodeo = satrec.nodeo * deg2rad;
    satrec.argpo = satrec.argpo * deg2rad;
    satrec.mo = satrec.mo * deg2rad;
 
    satrec.alta = satrec.a * (1.0 + satrec.ecco) - 1.0;
    satrec.altp = satrec.a * (1.0 - satrec.ecco) - 1.0;
 
    // ----------------------------------------------------------------
    // find sgp4epoch time of element set
    // remember that sgp4 uses units of days from 0 jan 1950 (sgp4epoch)
    // and minutes from the epoch (time)
    // ----------------------------------------------------------------
 
    // ---------------- temp fix for years from 1957-2056 -------------------
    // --------- correct fix will occur when year is 4-digit in tle ---------
    if (satrec.epochyr < 57)
        year = satrec.epochyr + 2000;
    else
        year = satrec.epochyr + 1900;
 
    days2mdhms(year, satrec.epochdays, mon, day, hr, minute, sec);
    jday(year, mon, day, hr, minute, sec, satrec.jdsatepoch);
 
    // ---- input start stop times manually
    if ((typerun != 'v') && (typerun != 'c'))
    {
        // ------------- enter start/stop ymd hms values --------------------
        if (typeinput == 'e')
        {
            printf("input start prop year mon day hr min sec \n");
            // make sure there is no space at the end of the format specifiers in silence = scanf!
            silence = scanf("%i %i %i %i %i %lf",
                            &startyear,
                            &startmon,
                            &startday,
                            &starthr,
                            &startmin,
                            &startsec);
            fflush(stdin);
            jday(startyear, startmon, startday, starthr, startmin, startsec, jdstart);
 
            printf("input stop prop year mon day hr min sec \n");
            silence = scanf("%i %i %i %i %i %lf",
                            &stopyear,
                            &stopmon,
                            &stopday,
                            &stophr,
                            &stopmin,
                            &stopsec);
            fflush(stdin);
            jday(stopyear, stopmon, stopday, stophr, stopmin, stopsec, jdstop);
 
            startmfe = (jdstart - satrec.jdsatepoch) * 1440.0;
            stopmfe = (jdstop - satrec.jdsatepoch) * 1440.0;
 
            printf("input time step in minutes \n");
            silence = scanf("%lf", &deltamin);
        }
        // -------- enter start/stop year and days of year values -----------
        if (typeinput == 'd')
        {
            printf("input start year dayofyr \n");
            silence = scanf("%i %lf", &startyear, &startdayofyr);
            printf("input stop year dayofyr \n");
            silence = scanf("%i %lf", &stopyear, &stopdayofyr);
 
            days2mdhms(startyear, startdayofyr, mon, day, hr, minute, sec);
            jday(startyear, mon, day, hr, minute, sec, jdstart);
            days2mdhms(stopyear, stopdayofyr, mon, day, hr, minute, sec);
            jday(stopyear, mon, day, hr, minute, sec, jdstop);
 
            startmfe = (jdstart - satrec.jdsatepoch) * 1440.0;
            stopmfe = (jdstop - satrec.jdsatepoch) * 1440.0;
 
            printf("input time step in minutes \n");
            silence = scanf("%lf", &deltamin);
        }
        // ------------------ enter start/stop mfe values -------------------
        if (typeinput == 'm')
        {
            printf("input start min from epoch \n");
            silence = scanf("%lf", &startmfe);
            printf("input stop min from epoch \n");
            silence = scanf("%lf", &stopmfe);
            printf("input time step in minutes \n");
            silence = scanf("%lf", &deltamin);
        }
    }
 
    // ------------ perform complete catalog evaluation, -+ 1 day -----------
    if (typerun == 'c')
    {
        startmfe = -1440.0;
        stopmfe = 1440.0;
        deltamin = 10.0;
    }
 
    // the compiler will only stop complaining if the variable is used
    silence += 1;
 
    // ---------------- initialize the orbit at sgp4epoch -------------------
    sgp4init(whichconst,
             opsmode,
             satrec.satnum,
             satrec.jdsatepoch - 2433281.5,
             satrec.bstar,
             satrec.ecco,
             satrec.argpo,
             satrec.inclo,
             satrec.mo,
             satrec.no,
             satrec.nodeo,
             satrec);
} // end twoline2rv