def calculate(stage, dset):
# CALCULATE
# -----------
# Correction of station position in GCRS due to loading and tide effects
site.calculate_site("site", dset)
delta_pos = site.add("site", dset)
dset.site_pos[:] = (dset.site_pos.gcrs + delta_pos[0].gcrs).trs
# Initialize models given in configuration file by adding model fields to Dataset
delay.calculate_delay("delay", dset)
delta_delay = delay.add("delay", dset)
if "observed" in dset.fields:
dset.observed[:] = gnss.get_code_observation(dset)
else:
dset.add_float("observed",
val=gnss.get_code_observation(dset),
unit="meter")
# Get model corrections
if "calc" in dset.fields:
dset.calc[:] = delta_delay
else:
dset.add_float("calc",
val=delta_delay,
unit="meter",
write_level="operational")
if "residual" in dset.fields:
dset.residual[:] = dset.observed - dset.calc
else:
dset.add_float("residual", val=dset.observed - dset.calc, unit="meter")
# Store calculate results
log.info(
f"{dset.num_obs} observations, residual = {dset.rms('residual'):.4f}")
dset.write_as(stage="calculate", dataset_id=0)
def calculate(stage, dset):
"""Estimate model parameters
Args:
rundate (Datetime): The model run date.
session (String): Name of session.
prev_stage (String): Name of previous stage.
stage (String): Name of current stage.
"""
# Run models adjusting station positions
log.info(f"Calculating station displacements")
site.calculate_site("site", dset)
delta_pos = site.add("site", dset)
dset.site_pos_1[:] = (dset.site_pos_1.gcrs + delta_pos[0].gcrs).trs
dset.site_pos_2[:] = (dset.site_pos_2.gcrs + delta_pos[1].gcrs).trs
log.blank()
# Run models for each term of the observation equation
log.info(f"Calculating theoretical delays")
delay.calculate_delay("delay", dset)
delta_delay = delay.add("delay", dset)
dset.add_float("obs",
val=dset.observed_delay,
unit="meter",
write_level="operational")
dset.add_float("calc",
val=delta_delay,
unit="meter",
write_level="operational")
dset.add_float("residual",
val=dset.obs - dset.calc,
unit="meter",
write_level="operational")
log.blank()
# Estimate clock polynomial
log.info(f"Calculating clock polynomials")
max_iterations = config.tech.calculate_max_iterations.int
outlier_limit = config.tech.calculate_outlier_limit.float
store_outliers = config.tech.store_outliers.bool
for iter_num in itertools.count(start=1):
delay.calculate_delay("delay_corr", dset, dset)
delta_correction = delay.add("delay_corr", dset)
dset.calc[:] = dset.calc + delta_correction
dset.residual[:] = dset.obs - dset.calc
rms = dset.rms("residual")
log.info(f"{dset.num_obs} observations, residual = {rms:.4f}")
# Store results
dset.write_as(stage=stage, label=iter_num - 1)
# Detect and remove extreme outliers
idx = np.abs(dset.residual) < outlier_limit * rms
if iter_num > max_iterations or idx.all():
break
if store_outliers:
bad_idx = np.logical_not(idx)
log.info(
f"Adding {np.sum(bad_idx)} observations to ignore_observation")
bad_obs = np.char.add(np.char.add(dset.time.utc.iso[bad_idx], " "),
dset.baseline[bad_idx]).tolist()
with config.update_tech_config(
dset.analysis["rundate"],
pipeline,
session=dset.vars["session"]) as cfg:
current = cfg.ignore_observation.observations.as_list(", *")
updated = ", ".join(sorted(current + bad_obs))
cfg.update("ignore_observation",
"observations",
updated,
source=util.get_program_name())
dset.subset(idx)
log.info(
f"Removing {sum(~idx)} observations with residuals bigger than {outlier_limit * rms}"
)
log.blank()
# Try to detect clock breaks
if config.tech.detect_clockbreaks.bool:
writers.write_one("vlbi_detect_clockbreaks", dset=dset)
dset.write()
def calculate(stage, dset):
"""
Integrate differential equation of motion of the satellite
Args:
stage: Name of current stage
dset: Dataset containing the data
"""
iterations = config.tech.iterations.int
# Run models adjusting station positions
site.calculate_site("site", dset)
delta_pos = site.add("site", dset)
dset.site_pos[:] = (dset.site_pos.gcrs + delta_pos[0].gcrs).trs
dset.add_float("obs",
val=dset.time_of_flight * constant.c / 2,
unit="meter")
dset.add_float("calc", np.zeros(dset.num_obs), unit="meter")
dset.add_float("residual", np.zeros(dset.num_obs), unit="meter")
dset.add_float("up_leg", np.zeros(dset.num_obs), unit="second")
dset.add_posvel("sat_pos",
np.zeros((dset.num_obs, 6)),
system="gcrs",
time=dset.time)
arc_length = config.tech.arc_length.float
dset.site_pos.other = dset.sat_pos
# First guess for up_leg:
dset.up_leg[:] = dset.time_of_flight / 2
for iter_num in itertools.count(start=1):
log.blank()
log.info(f"Calculating model corrections for iteration {iter_num}")
sat_time_list = dset.obs_time + dset.time_bias + dset.up_leg
apriori_orbit_provider = config.tech.apriori_orbit.str
sat_name = dset.vars["sat_name"]
rundate = dset.analysis["rundate"]
if apriori_orbit_provider:
version = config.tech.apriori_orbit_version.str
log.info(
f"Using external orbits from {apriori_orbit_provider}, version {version}"
)
apriori_orbit = apriori.get(
"orbit",
rundate=rundate + timedelta(days=arc_length),
time=None,
day_offset=6,
satellite=sat_name,
apriori_orbit="slr",
file_key="slr_external_orbits",
)
dset_external = apriori_orbit._read(dset, apriori_orbit_provider,
version)
sat_pos = dset_external.sat_pos.gcrs_pos
t_sec = TimeDelta(
dset_external.time -
Time(datetime(rundate.year, rundate.month, rundate.day),
scale="utc",
fmt="datetime"),
fmt="seconds",
)
t_sec = t_sec.value
else:
sat_pos, sat_vel, t_sec = orbit.calculate_orbit(
datetime(rundate.year, rundate.month, rundate.day),
sat_name,
sat_time_list,
return_full_table=True)
sat_pos_ip, sat_vel_ip = interpolation.interpolate_with_derivative(
np.array(t_sec),
sat_pos,
sat_time_list,
kind="interpolated_univariate_spline")
dset.sat_pos.gcrs[:] = np.concatenate((sat_pos_ip, sat_vel_ip), axis=1)
delay.calculate_delay("kinematic_models", dset)
# We observe the time when an observation is done, and the time of flight of the laser pulse. We estimate
# the up-leg time with Newton's method applied to the equation (8.84) of :cite:'beutler2005' Gerhard Beutler:
# Methods of Celestial Mechanics, Vol I., 2005.
for j in range(0, 4):
reflect_time = dset.time + TimeDelta(
dset.time_bias + dset.up_leg, fmt="seconds", scale="utc")
site_pos_reflect_time = (rotation.trs2gcrs(reflect_time)
@ dset.site_pos.trs.val[:, :, None])[:, :,
0]
sta_sat_vector = dset.sat_pos.gcrs.pos.val - site_pos_reflect_time
unit_vector = sta_sat_vector / np.linalg.norm(sta_sat_vector,
axis=1)[:, None]
rho12 = (np.linalg.norm(sta_sat_vector, axis=1) +
delay.add("kinematic_models", dset)) / constant.c
correction = (-dset.up_leg + rho12) / (
np.ones(dset.num_obs) - np.sum(
unit_vector / constant.c * dset.sat_pos.vel.val, axis=1))
dset.up_leg[:] += correction
sat_time_list = dset.obs_time + dset.time_bias + dset.up_leg
sat_pos_ip, sat_vel_ip = interpolation.interpolate_with_derivative(
np.array(t_sec),
sat_pos,
sat_time_list,
kind="interpolated_univariate_spline")
dset.sat_pos.gcrs[:] = np.concatenate((sat_pos_ip, sat_vel_ip),
axis=1)
delay.calculate_delay("satellite_models", dset)
dset.calc[:] = delay.add("satellite_models", dset)
dset.residual[:] = dset.obs - dset.calc
log.info(
f"{dset.num_obs} observations, residual = {dset.rms('residual'):.4f}"
)
if not apriori_orbit_provider:
orbit.update_orbit(sat_name, dset.site_pos.gcrs, dset.sat_pos.pos,
dset.sat_pos.vel, dset.residual, dset.bin_rms)
dset.write_as(stage=stage, label=iter_num, sat_name=sat_name)
if iter_num >= iterations:
break