def _calculate_pos_itrs(self, site):
"""Calculate positions for the given time epochs
The positions are calculated as simple linear offsets based on the reference epoch. If there is a post-seismic
deformations model for a station the motion due to that model is added to the linear velocity model. Makes sure
to pick out the correct time interval to use.
Args:
site (String): Key saying which site to calculate position for.
Returns:
Array: Positions, one 3-vector for each time epoch.
"""
station_info = self.data[site]
ref_epoch = Time(station_info["ref_epoch"], scale="utc")
pos = np.zeros((self.time.size, 3))
for pv in station_info["pos_vel"].values():
idx = np.logical_and(self.time.utc.datetime >= pv["start"],
self.time.utc.datetime < pv["end"])
if self.time.size == 1:
idx = np.array([idx])
if not any(idx):
continue
ref_pos = np.array([pv["STAX"], pv["STAY"], pv["STAZ"]])
ref_vel = np.array([pv["VELX"], pv["VELY"], pv["VELZ"]])
interval_years = (self.time - ref_epoch).jd * Unit.day2julian_years
if isinstance(interval_years, float):
interval_years = np.array([interval_years])
pos[idx, :] = ref_pos + interval_years[idx,
None] * ref_vel[None, :]
# Post-seismic deformations, see Appendix C in :cite:'itrf2014'
if "psd" in station_info:
llh = sofa.vectorized_llh(pos)
psd = station_info["psd"]
denu = dict(H=np.zeros(self.time.size),
E=np.zeros(self.time.size),
N=np.zeros(self.time.size))
for param in psd.values():
t_0 = Time(param["epoch"], format="datetime", scale="utc")
delta_t = (self.time - t_0).jd * Unit.day2julian_years
if isinstance(delta_t, float):
delta_t = np.array([delta_t])
idx = delta_t > 0
for L in "ENH":
aexp = np.array(param.get("AEXP_" + L, list()))
texp = np.array(param.get("TEXP_" + L, list()))
for a, t in zip(aexp, texp):
denu[L][idx] += a * (1 - np.exp(-delta_t[idx] / t))
alog = np.array(param.get("ALOG_" + L, list()))
tlog = np.array(param.get("TLOG_" + L, list()))
for a, t in zip(alog, tlog):
denu[L][idx] += a * np.log(1 + delta_t[idx] / t)
rot = rotation.enu2trs(llh[:, 0], llh[:, 1])
denu = np.vstack((denu["E"], denu["N"], denu["H"])).T
dxyz = (rot @ denu[:, :, None])[:, :, 0]
pos += dxyz
if self.time.size == 1:
pos = pos[0, :]
return pos
def setUp(self):
# TODO: Configuration has to be defined? How? where.set_config(2016, 3, 1, 'gps')?
time = Time(2457448.5, format="jd", scale="tdb") # Julian Day in TDB time scale
self.eph = apriori.get("ephemerides", time=time, ephemerides="de430")