/** SGP4SDP4 driver for doing AOS/LOS calculations.
* @param Predict_Sat $sat The satellite data.
* @param Predict_QTH $qth The QTH observer location data.
* @param float $t The time for calculation (Julian Date)
*
*/
public function predict_calc(Predict_Sat $sat, Predict_QTH $qth, $t)
{
$obs_set = new Predict_ObsSet();
$sat_geodetic = new Predict_Geodetic();
$obs_geodetic = new Predict_Geodetic();
$obs_geodetic->lon = $qth->lon * self::de2ra;
$obs_geodetic->lat = $qth->lat * self::de2ra;
$obs_geodetic->alt = $qth->alt / 1000.0;
$obs_geodetic->theta = 0;
$sat->jul_utc = $t;
$sat->tsince = ($sat->jul_utc - $sat->jul_epoch) * self::xmnpda;
/* call the norad routines according to the deep-space flag */
$sgpsdp = Predict_SGPSDP::getInstance($sat);
if ($sat->flags & Predict_SGPSDP::DEEP_SPACE_EPHEM_FLAG) {
$sgpsdp->SDP4($sat, $sat->tsince);
} else {
$sgpsdp->SGP4($sat, $sat->tsince);
}
Predict_Math::Convert_Sat_State($sat->pos, $sat->vel);
/* get the velocity of the satellite */
$sat->vel->w = sqrt($sat->vel->x * $sat->vel->x + $sat->vel->y * $sat->vel->y + $sat->vel->z * $sat->vel->z);
$sat->velo = $sat->vel->w;
Predict_SGPObs::Calculate_Obs($sat->jul_utc, $sat->pos, $sat->vel, $obs_geodetic, $obs_set);
Predict_SGPObs::Calculate_LatLonAlt($sat->jul_utc, $sat->pos, $sat_geodetic);
while ($sat_geodetic->lon < -self::pi) {
$sat_geodetic->lon += self::twopi;
}
while ($sat_geodetic->lon > self::pi) {
$sat_geodetic->lon -= self::twopi;
}
$sat->az = Predict_Math::Degrees($obs_set->az);
$sat->el = Predict_Math::Degrees($obs_set->el);
$sat->range = $obs_set->range;
$sat->range_rate = $obs_set->range_rate;
$sat->ssplat = Predict_Math::Degrees($sat_geodetic->lat);
$sat->ssplon = Predict_Math::Degrees($sat_geodetic->lon);
$sat->alt = $sat_geodetic->alt;
$sat->ma = Predict_Math::Degrees($sat->phase);
$sat->ma *= 256.0 / 360.0;
$sat->phase = Predict_Math::Degrees($sat->phase);
/* same formulas, but the one from predict is nicer */
//sat->footprint = 2.0 * xkmper * acos (xkmper/sat->pos.w);
$sat->footprint = 12756.33 * acos(self::xkmper / (self::xkmper + $sat->alt));
$age = $sat->jul_utc - $sat->jul_epoch;
$sat->orbit = floor(($sat->tle->xno * self::xmnpda / self::twopi + $age * $sat->tle->bstar * self::ae) * $age + $sat->tle->xmo / self::twopi) + $sat->tle->revnum - 1;
}
/** Initialise satellite data.
* @param sat The satellite to initialise.
* @param qth Optional QTH info, use (0,0) if NULL.
*
* This function calculates the satellite data at t = 0, ie. epoch time
* The function is called automatically by gtk_sat_data_read_sat.
*/
public function sat_data_init_sat(Predict_Sat $sat, Predict_QTH $qth = null)
{
$obs_geodetic = new Predict_Geodetic();
$obs_set = new Predict_ObsSet();
$sat_geodetic = new Predict_Geodetic();
/* double jul_utc, age; */
$jul_utc = Predict_Time::Julian_Date_of_Epoch($sat->tle->epoch);
// => tsince = 0.0
$sat->jul_epoch = $jul_utc;
/* initialise observer location */
if ($qth != null) {
$obs_geodetic->lon = $qth->lon * Predict::de2ra;
$obs_geodetic->lat = $qth->lat * Predict::de2ra;
$obs_geodetic->alt = $qth->alt / 1000.0;
$obs_geodetic->theta = 0;
} else {
$obs_geodetic->lon = 0.0;
$obs_geodetic->lat = 0.0;
$obs_geodetic->alt = 0.0;
$obs_geodetic->theta = 0;
}
/* execute computations */
$sdpsgp = Predict_SGPSDP::getInstance($sat);
if ($sat->flags & Predict_SGPSDP::DEEP_SPACE_EPHEM_FLAG) {
$sdpsgp->SDP4($sat, 0.0);
} else {
$sdpsgp->SGP4($sat, 0.0);
}
/* scale position and velocity to km and km/sec */
Predict_Math::Convert_Sat_State($sat->pos, $sat->vel);
/* get the velocity of the satellite */
$sat->vel->w = sqrt($sat->vel->x * $sat->vel->x + $sat->vel->y * $sat->vel->y + $sat->vel->z * $sat->vel->z);
$sat->velo = $sat->vel->w;
Predict_SGPObs::Calculate_Obs($jul_utc, $sat->pos, $sat->vel, $obs_geodetic, $obs_set);
Predict_SGPObs::Calculate_LatLonAlt($jul_utc, $sat->pos, $sat_geodetic);
while ($sat_geodetic->lon < -Predict::pi) {
$sat_geodetic->lon += Predict::twopi;
}
while ($sat_geodetic->lon > Predict::pi) {
$sat_geodetic->lon -= Predict::twopi;
}
$sat->az = Predict_Math::Degrees($obs_set->az);
$sat->el = Predict_Math::Degrees($obs_set->el);
$sat->range = $obs_set->range;
$sat->range_rate = $obs_set->range_rate;
$sat->ssplat = Predict_Math::Degrees($sat_geodetic->lat);
$sat->ssplon = Predict_Math::Degrees($sat_geodetic->lon);
$sat->alt = $sat_geodetic->alt;
$sat->ma = Predict_Math::Degrees($sat->phase);
$sat->ma *= 256.0 / 360.0;
$sat->footprint = 2.0 * Predict::xkmper * acos(Predict::xkmper / $sat->pos->w);
$age = 0.0;
$sat->orbit = floor(($sat->tle->xno * Predict::xmnpda / Predict::twopi + $age * $sat->tle->bstar * Predict::ae) * $age + $sat->tle->xmo / Predict::twopi) + $sat->tle->revnum - 1;
/* orbit type */
$sat->otype = $sat->get_orbit_type($sat);
}
