fsfw/coordinates/Sgp4Propagator.cpp

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2020-08-13 20:53:35 +02:00
#include "CoordinateTransformations.h"
#include "Sgp4Propagator.h"
#include "../globalfunctions/constants.h"
#include "../globalfunctions/math/MatrixOperations.h"
#include "../globalfunctions/math/VectorOperations.h"
#include "../globalfunctions/timevalOperations.h"
#include <cstring>
Sgp4Propagator::Sgp4Propagator() :
initialized(false), epoch({0, 0}), whichconst(wgs84) {
}
Sgp4Propagator::~Sgp4Propagator() {
}
void jday(int year, int mon, int day, int hr, int minute, double sec,
double& jd) {
jd = 367.0 * year - floor((7 * (year + floor((mon + 9) / 12.0))) * 0.25)
+ floor(275 * mon / 9.0) + day + 1721013.5
+ ((sec / 60.0 + minute) / 60.0 + hr) / 24.0; // ut in days
// - 0.5*sgn(100.0*year + mon - 190002.5) + 0.5;
}
void days2mdhms(int year, double days, int& mon, int& day, int& hr, int& minute,
double& sec) {
int i, inttemp, dayofyr;
double temp;
int lmonth[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
dayofyr = (int) floor(days);
/* ----------------- find month and day of month ---------------- */
if ((year % 4) == 0)
lmonth[1] = 29;
i = 1;
inttemp = 0;
while ((dayofyr > inttemp + lmonth[i - 1]) && (i < 12)) {
inttemp = inttemp + lmonth[i - 1];
i++;
}
mon = i;
day = dayofyr - inttemp;
/* ----------------- find hours minutes and seconds ------------- */
temp = (days - dayofyr) * 24.0;
hr = (int) floor(temp);
temp = (temp - hr) * 60.0;
minute = (int) floor(temp);
sec = (temp - minute) * 60.0;
}
ReturnValue_t Sgp4Propagator::initialize(const uint8_t* line1,
const uint8_t* line2) {
char longstr1[130];
char longstr2[130];
//need some space for decimal points
memcpy(longstr1, line1, 69);
memcpy(longstr2, line2, 69);
const double deg2rad = Math::PI / 180.0; // 0.0174532925199433
const double xpdotp = 1440.0 / (2.0 * Math::PI); // 229.1831180523293
double sec, mu, radiusearthkm, tumin, xke, j2, j3, j4, j3oj2;
int cardnumb, numb, j;
long revnum = 0, elnum = 0;
char classification, intldesg[11];
int year = 0;
int mon, day, hr, minute, nexp, ibexp;
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 (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);
double unixSeconds = (satrec.jdsatepoch - 2451544.5) * 24 * 3600
+ 946684800;
epoch.tv_sec = unixSeconds;
double subseconds = unixSeconds - epoch.tv_sec;
epoch.tv_usec = subseconds * 1000000;
// ---------------- initialize the orbit at sgp4epoch -------------------
uint8_t result = sgp4init(whichconst, satrec.satnum,
satrec.jdsatepoch - 2433281.5, satrec.bstar, satrec.ecco,
satrec.argpo, satrec.inclo, satrec.mo, satrec.no, satrec.nodeo,
satrec);
if (result != 00) {
return MAKE_RETURN_CODE(result);
} else {
initialized = true;
return HasReturnvaluesIF::RETURN_OK;
}
}
ReturnValue_t Sgp4Propagator::propagate(double* position, double* velocity,
timeval time, uint8_t gpsUtcOffset) {
if (!initialized) {
return TLE_NOT_INITIALIZED;
}
//Time since epoch in minutes
timeval timeSinceEpoch = time - epoch;
double minutesSinceEpoch = timeSinceEpoch.tv_sec / 60.
+ timeSinceEpoch.tv_usec / 60000000.;
double yearsSinceEpoch = minutesSinceEpoch / 60 / 24 / 365;
if ((yearsSinceEpoch > 1) || (yearsSinceEpoch < -1)) {
return TLE_TOO_OLD;
}
double positionTEME[3];
double velocityTEME[3];
uint8_t result = sgp4(whichconst, satrec, minutesSinceEpoch, positionTEME,
velocityTEME);
VectorOperations<double>::mulScalar(positionTEME, 1000, positionTEME, 3);
VectorOperations<double>::mulScalar(velocityTEME, 1000, velocityTEME, 3);
//Transform to ECF
double earthRotationMatrix[3][3];
CoordinateTransformations::getEarthRotationMatrix(time,
earthRotationMatrix);
MatrixOperations<double>::multiply(earthRotationMatrix[0], positionTEME,
position, 3, 3, 1);
MatrixOperations<double>::multiply(earthRotationMatrix[0], velocityTEME,
velocity, 3, 3, 1);
double omegaEarth[3] = { 0, 0, Earth::OMEGA };
double velocityCorrection[3];
VectorOperations<double>::cross(omegaEarth, position, velocityCorrection);
VectorOperations<double>::subtract(velocity, velocityCorrection, velocity);
if (result != 0) {
return MAKE_RETURN_CODE(result || 0xB0);
} else {
return HasReturnvaluesIF::RETURN_OK;
}
}