def generate_sat_obj_list():
"""
Generates list of satellite objects based on orbital elements
:return: List of satellites
"""
global sat_objs
sat_objs = [None] * NUM_SHELLS
for shell_cntr in range(0, NUM_SHELLS):
sat_objs[shell_cntr] = [None] * (NUM_ORBS[shell_cntr] *
NUM_SATS_PER_ORB[shell_cntr])
counter = 0
for orb in range(0, NUM_ORBS[shell_cntr]):
raan = orb * 360 / NUM_ORBS[shell_cntr]
orbit_wise_shift = 0
if orb % 2 == 1:
if PHASE_DIFF == 'Y':
orbit_wise_shift = 360 / (NUM_SATS_PER_ORB[shell_cntr] * 2)
for n_sat in range(0, NUM_SATS_PER_ORB[shell_cntr]):
mean_anomaly = orbit_wise_shift + (
n_sat * 360 / NUM_SATS_PER_ORB[shell_cntr])
sat = ephem.EarthSatellite()
sat._epoch = EPOCH
sat._inc = ephem.degrees(INCLINATION_DEGREE[shell_cntr])
sat._e = ECCENTRICITY
sat._raan = ephem.degrees(raan)
sat._ap = ARG_OF_PERIGEE
sat._M = ephem.degrees(mean_anomaly)
sat._n = MEAN_MOTION_REV_PER_DAY[shell_cntr]
sat_objs[shell_cntr][counter] = sat
counter += 1
return sat_objs
def generate_sat_obj_list(num_orbit, num_sats_per_orbit, epoch, phase_diff,
inclination, eccentricity, arg_perigee, mean_motion,
altitude):
"""
Generates list of satellite objects based on orbital elements
:param num_orbit: Number of orbits
:param num_sats_per_orbit: Number of satellites per orbit
:param epoch: Epoch (start time)
:param phase_diff: Phase difference between adjacent orbits
:param inclination: Angle of inclination
:param eccentricity: Eccentricity of orbits
:param arg_perigee: Argument of perigee of orbits
:param mean_motion: Mean motion in revolutions per day
:param altitude: Altitude in metres
:return: List of satellite objects
"""
sat_objs = [None] * (num_orbit * num_sats_per_orbit)
counter = 0
for orb in range(0, num_orbit):
raan = orb * 360 / num_orbit
orbit_wise_shift = 0
if orb % 2 == 1:
if phase_diff:
orbit_wise_shift = 360 / (num_sats_per_orbit * 2)
for n_sat in range(0, num_sats_per_orbit):
mean_anomaly = orbit_wise_shift + (n_sat * 360 /
num_sats_per_orbit)
sat = ephem.EarthSatellite()
sat._epoch = epoch
sat._inc = ephem.degrees(inclination)
sat._e = eccentricity
sat._raan = ephem.degrees(raan)
sat._ap = arg_perigee
sat._M = ephem.degrees(mean_anomaly)
sat._n = mean_motion
sat_objs[counter] = {
"sat_obj": sat,
"alt_km": altitude / 1000,
"orb_id": orb,
"orb_sat_id": n_sat
}
counter += 1
return sat_objs
def constellationFromSaVi():
DELETE_FROM_BEGINING = 3
DELETE_FROM_END = 2
constellation = list()
with open(TCL_FILE_NAME, 'r') as tclfile:
#we read from the TCL file and obtain a list containing SATELLITES_PER_ORBIT*NUMBER_OF_ORBITS
#Attention : these elements are each one list(string) of size 1
spaceX_SaVi = list(csv.reader(tclfile, delimiter='\n'))
#we delete the lines that do not give any infomation for the satellites
for i in range(0, DELETE_FROM_BEGINING):
spaceX_SaVi.pop(0)
for i in range(0, DELETE_FROM_END):
spaceX_SaVi.pop(len(spaceX_SaVi) - 1)
if len(spaceX_SaVi) != SATELLITES_PER_ORBIT * NUMBER_OF_ORBITS:
raise Exception('The total number of satellites is not correct')
for i in range(0, NUMBER_OF_ORBITS):
orbit_i = list()
for j in range(0, SATELLITES_PER_ORBIT):
SaVi_line = spaceX_SaVi.pop(0)[0].split()
for i in range(0, 2):
SaVi_line.pop(0)
to_add_sat = ephem.EarthSatellite()
to_add_sat._epoch = EPOCH #ok
to_add_sat._n = geom.semi_major_to_mean_motion(
float(SaVi_line[0])) #ok
to_add_sat._e = float(SaVi_line[1]) + ECCENTRICITY_ADJUSTMENT #ok
to_add_sat._inc = float(SaVi_line[2]) #ok
to_add_sat._raan = float(SaVi_line[3]) #ok
to_add_sat._ap = float(SaVi_line[4]) #ok
to_add_sat._M = geom.time_to_periapsis_to_mean_anomaly(
float(SaVi_line[5]), to_add_sat._n) #ok
to_add_sat._drag = 0.0
orbit_i.append(to_add_sat)
constellation.append(orbit_i)
return constellation
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
import ephem
import math
import sys
# Generate a satellite from orbital elements
# Check parent script 02_get_sat_positions_at_time.sh for the arguments supplied
sat1 = ephem.EarthSatellite()
sat1._epoch = sys.argv[1] + ' ' + sys.argv[2]
sat1._inc = ephem.degrees(float(sys.argv[9]))
sat1._e = float(sys.argv[10])
sat1._raan = ephem.degrees(float(sys.argv[5]))
sat1._ap = float(sys.argv[11])
sat1._M = ephem.degrees(float(sys.argv[6]))
sat1._n = float(sys.argv[12])
sat1.compute(sys.argv[3] + ' ' + sys.argv[4])
counter = sys.argv[7]
num_orbit = sys.argv[8]
num_sat_in_orbit = sys.argv[13]
# Print the satellite position in terms of coordinates and elevation
print('%d %d %d %s %s %s' %
(int(counter), int(num_orbit), int(num_sat_in_orbit),
math.degrees(sat1.sublat), math.degrees(sat1.sublong), sat1.elevation))
def earthsat_builder(df, ob_lat, ob_lon, ob_alt, ddate, cn):
"""
:param df:
:param ob_lat:
:param ob_lon:
:param ob_alt:
:param ddate:
:param cn:
:return: DataFrame
Observer: Obs
- Computes the position of the Body.
- Uses the date of the observer.
- Uses the epoch of the observer.
lon,lat : Latitude and longitude (String)
elevation : (Int)
ddate : (String) (date format : '1984/5/30 16:22:56' )
earthSat : (ephem.Body)
"""
g = 6.67408e-11
m_earth = 5.97219e24
column_to_add = ["el", "az", "rx_lon", "rx_lat", "rx_alt", "cn0", "ddate"]
for col in range(len(column_to_add)):
df[column_to_add[col]] = np.nan
res=pd.DataFrame()
for rx_lat, rx_lon, rx_alt, rx_date, signal_cn in zip(ob_lat, ob_lon, ob_alt, ddate, cn):
act_df = df
ob_lon = np.deg2rad(rx_lon)
ob_lat = np.deg2rad(rx_lat)
obs = ephem.Observer()
obs.lat = np.deg2rad(ob_lat)
obs.long = np.deg2rad(ob_lon)
obs.elevation = rx_alt
for index, row in act_df.iterrows():
esat = ephem.EarthSatellite()
esat._e = act_df.at[index, 'Eccentricity']
esat._M = np.rad2deg(act_df.at[index, 'Mean Anom(rad)'])
esat._ap = np.rad2deg(act_df.at[index, 'Argument of Perigee(rad)'])
esat._raan = np.rad2deg(act_df.at[index, 'Right Ascen at Week(rad)'])
esat._n = np.sqrt(g * m_earth / (act_df.at[index, 'SQRT(A) (m 1/2)'] ** 2) ** 3) * (86400 / (2 * np.pi))
esat._epoch = ephem.Date(rx_date)
esat._inc = np.rad2deg(act_df.at[index, 'Orbital Inclination(rad)'])
obs.date = ephem.Date(rx_date.strftime('%Y/%-m/%-d %H:%M:%S'))
esat.compute(obs)
values = [np.rad2deg(esat.alt), np.rad2deg(esat.az), rx_lon,
rx_lat, rx_alt, signal_cn, rx_date]
for i in range(len(values)):
act_df.set_value(index, column_to_add[i], values[i])
res=pd.concat([res, act_df])
res=res.reset_index(drop=True)
return df_filter_info(res)