public void PassPrediction() { List <PassDetails> knownPasses = SetupKnownPasses(); CoordGeodetic geo = new CoordGeodetic(41.760612, -111.819384, 1.394); Tle tle = new Tle("ISS (ZARYA)", "1 25544U 98067A 15090.55997958 .00016867 00000-0 24909-3 0 9997", "2 25544 51.6467 111.8303 0006284 156.4629 341.9393 15.55450652935952"); SGP4 sgp4 = new SGP4(tle); /* * generate 7 day schedule */ DateTime start_date = new DateTime(2015, 4, 13, 0, 0, 0); //DateTime.Now (true); DateTime end_date = start_date.AddDays(7); //new DateTime (System.DateTime.Now.AddDays (7)); List <PassDetails> pass_list = new List <PassDetails>(); ; //Console.WriteLine("Start time: " + start_date.ToString()); //Console.WriteLine("End time : " + end_date.ToString()); /* * generate passes */ pass_list = GeneratePassList(geo, sgp4, start_date, end_date, 180); Assert.AreEqual(knownPasses.Count, pass_list.Count); for (int i = 0; i < pass_list.Count; ++i) { Assert.AreEqual(knownPasses[i].ToString(), pass_list[i].ToString()); } }
private bool IsEqual(CoordGeodetic geo) { bool equal = false; if (latitude == geo.latitude && longitude == geo.longitude && altitude == geo.altitude) { equal = false; } return(equal); }
private void ToEci(DateTime dt, CoordGeodetic geo) { /* * set date */ m_dt = dt; const double mfactor = Global.kTWOPI * (Global.kOMEGA_E / Global.kSECONDS_PER_DAY); /* * Calculate Local Mean Sidereal Time for observers longitude */ double theta = m_dt.ToLocalMeanSiderealTime(geo.longitude); /* * take into account earth flattening */ double c = 1.0 / Math.Sqrt(1.0 + Global.kF * (Global.kF - 2.0) * Math.Pow(Math.Sin(geo.latitude), 2.0)); double s = Math.Pow(1.0 - Global.kF, 2.0) * c; double achcp = (Global.kXKMPER * c + geo.altitude) * Math.Cos(geo.latitude); /* * X position in km * Y position in km * Z position in km * W magnitude in km */ m_position.x = achcp * Math.Cos(theta); m_position.y = achcp * Math.Sin(theta); m_position.z = (Global.kXKMPER * s + geo.altitude) * Math.Sin(geo.latitude); m_position.w = m_position.Magnitude(); /* * X velocity in km/s * Y velocity in km/s * Z velocity in km/s * W magnitude in km/s */ m_velocity.x = -mfactor * m_position.y; m_velocity.y = mfactor * m_position.x; m_velocity.z = 0.0; m_velocity.w = m_velocity.Magnitude(); }
/** * Update this object with a new date and geodetic position * @param dt new date * @param geo new geodetic position */ public void Update(DateTime dt, CoordGeodetic geo) { ToEci(dt, geo); }
/** * @param[in] dt the date to be used for this position * @param[in] geo the position */ public Eci(DateTime dt, CoordGeodetic geo) { ToEci(dt, geo); }
/** * Set the observers location * @param[in] geo the observers position */ public void SetLocation(CoordGeodetic geo) { m_geo = geo; m_eci.Update(m_eci.GetDateTime(), m_geo); }
/** * Constructor * @param[in] geo the observers position */ public Observer(CoordGeodetic geo) { m_geo = new CoordGeodetic(geo); m_eci = new Eci(new DateTime(), geo); }
/** * ructor * @param[in] latitude observers latitude in degrees * @param[in] longitude observers longitude in degrees * @param[in] altitude observers altitude in kilometers */ public Observer(double latitude, double longitude, double altitude) { m_geo = new CoordGeodetic(latitude, longitude, altitude); m_eci = new Eci(new DateTime(), m_geo); }
public static DateTime FindCrossingPoint(CoordGeodetic user_geo, SGP4 sgp4, DateTime initial_time1, DateTime initial_time2, bool finding_aos) { Observer obs = new Observer(user_geo); bool running; int cnt; DateTime time1 = new DateTime(initial_time1.Ticks()); DateTime time2 = new DateTime(initial_time2.Ticks()); DateTime middle_time = null; running = true; cnt = 0; while (running && cnt++ < 16) { middle_time = time1.AddSeconds((time2 - time1).TotalSeconds() / 2.0); /* * calculate satellite position */ Eci eci = sgp4.FindPosition(middle_time); CoordTopocentric topo = obs.GetLookAngle(eci); if (topo.elevation > 0.0) { /* * satellite above horizon */ if (finding_aos) { time2 = middle_time; } else { time1 = middle_time; } } else { if (finding_aos) { time1 = middle_time; } else { time2 = middle_time; } } if ((time2 - time1).TotalSeconds() < 1.0) { /* * two times are within a second, stop */ running = false; /* * remove microseconds */ int us = middle_time.Microsecond(); middle_time = middle_time.AddMicroseconds(-us); /* * step back into the pass by 1 second */ middle_time = middle_time.AddSeconds(finding_aos ? 1 : -1); } } /* * go back/forward 1second until below the horizon */ running = true; cnt = 0; while (running && cnt++ < 6) { Eci eci = sgp4.FindPosition(middle_time); CoordTopocentric topo = obs.GetLookAngle(eci); if (topo.elevation > 0) { middle_time = middle_time.AddSeconds(finding_aos ? -1 : 1); } else { running = false; } } return(middle_time); }
public static double FindMaxElevation(CoordGeodetic user_geo, SGP4 sgp4, DateTime aos, DateTime los) { Observer obs = new Observer(user_geo); bool running; double time_step = (los - aos).TotalSeconds() / 9.0; DateTime current_time = aos; //! current time DateTime time1 = aos; //! start time of search period DateTime time2 = los; //! end time of search period double max_elevation; //! max elevation running = true; do { running = true; max_elevation = -99999999999999.0; while (running && current_time < time2) { /* * find position */ Eci eci = sgp4.FindPosition(current_time); CoordTopocentric topo = obs.GetLookAngle(eci); if (topo.elevation > max_elevation) { /* * still going up */ max_elevation = topo.elevation; /* * move time along */ current_time = current_time.AddSeconds(time_step); if (current_time > time2) { /* * dont go past end time */ current_time = time2; } } else { /* * stop */ running = false; } } /* * make start time to 2 time steps back */ time1 = current_time.AddSeconds(-2.0 * time_step); /* * make end time to current time */ time2 = current_time; /* * current time to start time */ current_time = time1; /* * recalculate time step */ time_step = (time2 - time1).TotalSeconds() / 9.0; } while (time_step > 1.0); return(max_elevation); }
public static List <PassDetails> GeneratePassList(CoordGeodetic user_geo, SGP4 sgp4, DateTime start_time, DateTime end_time, int time_step) { List <PassDetails> pass_list = new List <PassDetails>(); Observer obs = new Observer(user_geo); DateTime aos_time = null; DateTime los_time = null; bool found_aos = false; DateTime previous_time = new DateTime(start_time.Ticks()); DateTime current_time = new DateTime(start_time.Ticks()); while (current_time < end_time) { bool end_of_pass = false; /* * calculate satellite position */ Eci eci = sgp4.FindPosition(current_time); CoordTopocentric topo = obs.GetLookAngle(eci); if (!found_aos && topo.elevation > 0.0) { /* * aos hasnt occured yet, but the satellite is now above horizon * this must have occured within the last time_step */ if (start_time == current_time) { /* * satellite was already above the horizon at the start, * so use the start time */ aos_time = start_time; } else { /* * find the point at which the satellite crossed the horizon */ aos_time = FindCrossingPoint( user_geo, sgp4, previous_time, current_time, true); } found_aos = true; } else if (found_aos && topo.elevation < 0.0) { found_aos = false; /* * end of pass, so move along more than time_step */ end_of_pass = true; /* * already have the aos, but now the satellite is below the horizon, * so find the los */ los_time = FindCrossingPoint(user_geo, sgp4, previous_time, current_time, false); PassDetails pd = new PassDetails(); pd.aos = aos_time; pd.los = los_time; pd.max_elevation = FindMaxElevation(user_geo, sgp4, aos_time, los_time); pass_list.Add(pd); } /* * save current time */ previous_time = current_time; if (end_of_pass) { /* * at the end of the pass move the time along by 30mins */ current_time = current_time.AddMinutes(30); } else { /* * move the time along by the time step value */ current_time = current_time.AddSeconds(180); } if (current_time > end_time) { /* * dont go past end time */ current_time = end_time; } } ; if (found_aos) { /* * satellite still above horizon at end of search period, so use end * time as los */ PassDetails pd = new PassDetails(); pd.aos = aos_time; pd.los = end_time; pd.max_elevation = FindMaxElevation(user_geo, sgp4, aos_time, end_time); pass_list.Add(pd); } return(pass_list); }
/** * Copy constructor * @param[in] geo object to copy from */ public CoordGeodetic(CoordGeodetic geo) { latitude = geo.latitude; longitude = geo.longitude; altitude = geo.altitude; }