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pedromiguelcp
2025-08-13 15:01:13 +01:00
parent 0cf75d15aa
commit dad143ace0
1 changed files with 186 additions and 253 deletions
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utils/skyplot/skyplot.py
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@@ -1,21 +1,21 @@
#!/usr/bin/env python
"""
skyplot.py
skyplot.py
Reads a RINEX navigation file and generates a skyplot. Optionally, a RINEX observation file can
also be read to match the skyplot to the receiver processing time.
Reads a RINEX navigation file and generates a skyplot. Optionally, a RINEX observation file can
also be read to match the skyplot to the receiver processing time.
Usage: python skyplot.py <RINEX_NAV_FILE> [observer_lat] [observer_lon] [observer_alt] [--use-obs]
Usage: python skyplot.py <RINEX_NAV_FILE> [observer_lat] [observer_lon] [observer_alt] [--use-obs]
-----------------------------------------------------------------------------
-----------------------------------------------------------------------------
GNSS-SDR is a Global Navigation Satellite System software-defined receiver.
This file is part of GNSS-SDR.
GNSS-SDR is a Global Navigation Satellite System software-defined receiver.
This file is part of GNSS-SDR.
SPDX-FileCopyrightText: 2025 Carles Fernandez-Prades cfernandez(at)cttc.es
SPDX-License-Identifier: GPL-3.0-or-later
SPDX-FileCopyrightText: 2025 Carles Fernandez-Prades cfernandez(at)cttc.es
SPDX-License-Identifier: GPL-3.0-or-later
-----------------------------------------------------------------------------
-----------------------------------------------------------------------------
"""
import argparse
@@ -30,20 +30,19 @@ import numpy as np
def _read_obs_time_bounds(obs_path):
"""
Return (start_time, end_time) from a RINEX 2/3 OBS file by scanning epoch lines.
"""Return (start_time, end_time) from a RINEX 2/3 OBS file by scanning epoch lines.
If parsing fails or the file is not OBS, return (None, None).
"""
try:
with open(obs_path, "r", encoding="utf-8", errors="ignore") as f:
with open(obs_path, 'r', encoding='utf-8', errors='ignore') as f:
# Detect OBS in header and skip to END OF HEADER
is_obs = False
for line in f:
if "RINEX VERSION / TYPE" in line:
# Robust OBS detection:
# - In RINEX 2/3 the file-type letter at col 21 (0-based idx 20)
# In RINEX 2/3 the file-type letter at col 21 (0-based idx 20)
tchar = line[20:21]
if tchar == "O" or "OBSERVATION DATA" in line:
if tchar == 'O' or 'OBSERVATION DATA' in line:
is_obs = True
if "END OF HEADER" in line:
break
@@ -56,27 +55,17 @@ def _read_obs_time_bounds(obs_path):
for line in f:
if not line.strip():
continue
if line.startswith(">"): # RINEX 3 epoch line
yyyy = int(line[2:6])
mm = int(line[7:9])
dd = int(line[10:12])
hh = int(line[13:15])
mi = int(line[16:18])
ss = float(line[19:29])
epoch = datetime(yyyy, mm, dd, hh, mi, int(ss), int((ss % 1) * 1e6))
if line.startswith('>'): # RINEX 3 epoch line
yyyy = int(line[2:6]); mm = int(line[7:9]); dd = int(line[10:12])
hh = int(line[13:15]); mi = int(line[16:18]); ss = float(line[19:29])
epoch = datetime(yyyy, mm, dd, hh, mi, int(ss), int((ss % 1)*1e6))
else:
# RINEX 2 epoch line
try:
yy = int(line[1:3])
mm = int(line[4:6])
dd = int(line[7:9])
hh = int(line[10:12])
mi = int(line[13:15])
ss = float(line[15:26])
yy = int(line[1:3]); mm = int(line[4:6]); dd = int(line[7:9])
hh = int(line[10:12]); mi = int(line[13:15]); ss = float(line[15:26])
yyyy = 1900 + yy if yy >= 80 else 2000 + yy
epoch = datetime(
yyyy, mm, dd, hh, mi, int(ss), int((ss % 1) * 1e6)
)
epoch = datetime(yyyy, mm, dd, hh, mi, int(ss), int((ss % 1)*1e6))
except Exception:
continue
if start_time is None or epoch < start_time:
@@ -95,22 +84,22 @@ def parse_rinex_float(s):
return 0.0
# Replace D exponent with E (some RINEX files use D instead of E)
s = s.replace("D", "E").replace("d", "e")
s = s.replace('D', 'E').replace('d', 'e')
# Handle cases where exponent lacks E (e.g., "12345-3")
if re.match(r"[+-]?\d+[+-]\d+", s.strip()):
s = s.replace("+", "E+").replace("-", "E-")
if re.match(r'[+-]?\d+[+-]\d+', s.strip()):
s = s.replace('+', 'E+').replace('-', 'E-')
try:
return float(s)
except ValueError:
# Handle cases where the number runs into the next field
# Try to split at the exponent if present
if "E" in s:
base, exp = s.split("E")[:2]
if 'E' in s:
base, exp = s.split('E')[:2]
# Take first character of exponent if needed
if exp and exp[0] in "+-" and len(exp) > 1:
return float(base + "E" + exp[0] + exp[1:].split()[0])
if exp and exp[0] in '+-' and len(exp) > 1:
return float(base + 'E' + exp[0] + exp[1:].split()[0])
return 0.0 # Default if parsing fails
@@ -118,7 +107,7 @@ def read_rinex_nav(filename):
"""Read RINEX v3.0 navigation file"""
satellites = {}
line_number = 0
with open(filename, "r", encoding="utf-8") as f:
with open(filename, 'r', encoding='utf-8') as f:
# Skip header
while True:
line = f.readline()
@@ -154,7 +143,7 @@ def read_rinex_nav(filename):
# Read the next lines
lines = [current_line]
line_count = 4 if system == "R" else 7
line_count = 4 if system == 'R' else 7
for _ in range(line_count):
next_line = f.readline()
line_number += 1
@@ -167,64 +156,61 @@ def read_rinex_nav(filename):
line_number += 1
continue
if system == "R": # GLONASS specific parsing
if system == 'R': # GLONASS specific parsing
ephemeris = {
"prn": prn,
"epoch": epoch,
"sv_clock_bias": parse_rinex_float(lines[0][23:42]),
"sv_relative_freq_bias": parse_rinex_float(lines[0][42:61]),
"message_frame_time": parse_rinex_float(lines[0][61:80]),
"x": parse_rinex_float(lines[1][4:23]), # Position (km)
"x_vel": parse_rinex_float(lines[1][23:42]), # Velocity (km/s)
"x_acc": parse_rinex_float(lines[1][42:61]),
"health": parse_rinex_float(lines[1][61:80]),
"y": parse_rinex_float(lines[2][4:23]),
"y_vel": parse_rinex_float(lines[2][23:42]),
"y_acc": parse_rinex_float(lines[2][42:61]),
"freq_num": parse_rinex_float(lines[2][61:80]),
"z": parse_rinex_float(lines[3][4:23]),
"z_vel": parse_rinex_float(lines[3][23:42]),
"z_acc": parse_rinex_float(lines[3][42:61]),
"age": parse_rinex_float(lines[3][61:80]),
'prn': prn,
'epoch': epoch,
'sv_clock_bias': parse_rinex_float(lines[0][23:42]),
'sv_relative_freq_bias': parse_rinex_float(lines[0][42:61]),
'message_frame_time': parse_rinex_float(lines[0][61:80]),
'x': parse_rinex_float(lines[1][4:23]), # Position (km)
'x_vel': parse_rinex_float(lines[1][23:42]), # Velocity (km/s)
'x_acc': parse_rinex_float(lines[1][42:61]),
'health': parse_rinex_float(lines[1][61:80]),
'y': parse_rinex_float(lines[2][4:23]),
'y_vel': parse_rinex_float(lines[2][23:42]),
'y_acc': parse_rinex_float(lines[2][42:61]),
'freq_num': parse_rinex_float(lines[2][61:80]),
'z': parse_rinex_float(lines[3][4:23]),
'z_vel': parse_rinex_float(lines[3][23:42]),
'z_acc': parse_rinex_float(lines[3][42:61]),
'age': parse_rinex_float(lines[3][61:80])
}
else:
# Parse all ephemeris parameters
ephemeris = {
"prn": prn,
"epoch": epoch,
"sv_clock_bias": parse_rinex_float(lines[0][23:42]),
"sv_clock_drift": parse_rinex_float(lines[0][42:61]),
"sv_clock_drift_rate": parse_rinex_float(lines[0][61:80]),
"iode": parse_rinex_float(lines[1][4:23]),
"crs": parse_rinex_float(lines[1][23:42]),
"delta_n": parse_rinex_float(lines[1][42:61]),
"m0": parse_rinex_float(lines[1][61:80]),
"cuc": parse_rinex_float(lines[2][4:23]),
"ecc": parse_rinex_float(lines[2][23:42]),
"cus": parse_rinex_float(lines[2][42:61]),
"sqrt_a": parse_rinex_float(lines[2][61:80]),
"toe": parse_rinex_float(lines[3][4:23]),
"cic": parse_rinex_float(lines[3][23:42]),
"omega0": parse_rinex_float(lines[3][42:61]),
"cis": parse_rinex_float(lines[3][61:80]),
"i0": parse_rinex_float(lines[4][4:23]),
"crc": parse_rinex_float(lines[4][23:42]),
"omega": parse_rinex_float(lines[4][42:61]),
"omega_dot": parse_rinex_float(lines[4][61:80]),
"idot": parse_rinex_float(lines[5][4:23]),
"codes_l2": parse_rinex_float(lines[5][23:42]),
"gps_week": parse_rinex_float(lines[5][42:61]),
"l2p_flag": parse_rinex_float(lines[5][61:80]),
"sv_accuracy": parse_rinex_float(lines[6][4:23]),
"sv_health": parse_rinex_float(lines[6][23:42]),
"tgd": parse_rinex_float(lines[6][42:61]),
"iodc": parse_rinex_float(lines[6][61:80]),
"transmission_time": parse_rinex_float(lines[7][4:23]),
"fit_interval": (
(parse_rinex_float(lines[7][23:42]))
if len(lines[7]) > 23
else 0.0
),
'prn': prn,
'epoch': epoch,
'sv_clock_bias': parse_rinex_float(lines[0][23:42]),
'sv_clock_drift': parse_rinex_float(lines[0][42:61]),
'sv_clock_drift_rate': parse_rinex_float(lines[0][61:80]),
'iode': parse_rinex_float(lines[1][4:23]),
'crs': parse_rinex_float(lines[1][23:42]),
'delta_n': parse_rinex_float(lines[1][42:61]),
'm0': parse_rinex_float(lines[1][61:80]),
'cuc': parse_rinex_float(lines[2][4:23]),
'ecc': parse_rinex_float(lines[2][23:42]),
'cus': parse_rinex_float(lines[2][42:61]),
'sqrt_a': parse_rinex_float(lines[2][61:80]),
'toe': parse_rinex_float(lines[3][4:23]),
'cic': parse_rinex_float(lines[3][23:42]),
'omega0': parse_rinex_float(lines[3][42:61]),
'cis': parse_rinex_float(lines[3][61:80]),
'i0': parse_rinex_float(lines[4][4:23]),
'crc': parse_rinex_float(lines[4][23:42]),
'omega': parse_rinex_float(lines[4][42:61]),
'omega_dot': parse_rinex_float(lines[4][61:80]),
'idot': parse_rinex_float(lines[5][4:23]),
'codes_l2': parse_rinex_float(lines[5][23:42]),
'gps_week': parse_rinex_float(lines[5][42:61]),
'l2p_flag': parse_rinex_float(lines[5][61:80]),
'sv_accuracy': parse_rinex_float(lines[6][4:23]),
'sv_health': parse_rinex_float(lines[6][23:42]),
'tgd': parse_rinex_float(lines[6][42:61]),
'iodc': parse_rinex_float(lines[6][61:80]),
'transmission_time': parse_rinex_float(lines[7][4:23]),
'fit_interval': (
parse_rinex_float(lines[7][23:42])) if len(lines[7]) > 23 else 0.0
}
if prn not in satellites:
@@ -252,60 +238,52 @@ def read_rinex_nav(filename):
def calculate_satellite_position(ephemeris, transmit_time):
"""Calculate satellite position in ECEF coordinates at given transmission time"""
system = ephemeris["prn"][0]
system = ephemeris['prn'][0]
if system == "R": # GLONASS - use position + velocity * time
if system == 'R': # GLONASS - use position + velocity * time
dt = transmit_time
# Convert km to meters
xk = (
ephemeris["x"] + ephemeris["x_vel"] * dt + 0.5 * ephemeris["x_acc"] * dt**2
) * 1000
yk = (
ephemeris["y"] + ephemeris["y_vel"] * dt + 0.5 * ephemeris["y_acc"] * dt**2
) * 1000
zk = (
ephemeris["z"] + ephemeris["z_vel"] * dt + 0.5 * ephemeris["z_acc"] * dt**2
) * 1000
xk = (ephemeris['x'] + ephemeris['x_vel'] * dt + 0.5 * ephemeris['x_acc'] * dt**2) * 1000
yk = (ephemeris['y'] + ephemeris['y_vel'] * dt + 0.5 * ephemeris['y_acc'] * dt**2) * 1000
zk = (ephemeris['z'] + ephemeris['z_vel'] * dt + 0.5 * ephemeris['z_acc'] * dt**2) * 1000
else:
# Constants
mu = 3.986005e14 # Earth's gravitational constant (m^3/s^2)
omega_e_dot = 7.2921151467e-5 # Earth rotation rate (rad/s)
# Semi-major axis
a = ephemeris["sqrt_a"] ** 2
a = ephemeris['sqrt_a'] ** 2
# Corrected mean motion
n0 = sqrt(mu / (a**3))
n = n0 + ephemeris["delta_n"]
n0 = sqrt(mu / (a ** 3))
n = n0 + ephemeris['delta_n']
# Mean anomaly
mk = ephemeris["m0"] + n * transmit_time
mk = ephemeris['m0'] + n * transmit_time
# Solve Kepler's equation for eccentric anomaly (Ek)
ek = mk
for _ in range(10):
ek_old = ek
ek = mk + ephemeris["ecc"] * sin(ek)
ek = mk + ephemeris['ecc'] * sin(ek)
if abs(ek - ek_old) < 1e-12:
break
# True anomaly
nu_k = atan2(
sqrt(1 - ephemeris["ecc"] ** 2) * sin(ek), cos(ek) - ephemeris["ecc"]
)
nu_k = atan2(sqrt(1 - ephemeris['ecc']**2) * sin(ek), cos(ek) - ephemeris['ecc'])
# Argument of latitude
phi_k = nu_k + ephemeris["omega"]
phi_k = nu_k + ephemeris['omega']
# Second harmonic perturbations
delta_uk = ephemeris["cus"] * sin(2 * phi_k) + ephemeris["cuc"] * cos(2 * phi_k)
delta_rk = ephemeris["crs"] * sin(2 * phi_k) + ephemeris["crc"] * cos(2 * phi_k)
delta_ik = ephemeris["cis"] * sin(2 * phi_k) + ephemeris["cic"] * cos(2 * phi_k)
delta_uk = ephemeris['cus'] * sin(2 * phi_k) + ephemeris['cuc'] * cos(2 * phi_k)
delta_rk = ephemeris['crs'] * sin(2 * phi_k) + ephemeris['crc'] * cos(2 * phi_k)
delta_ik = ephemeris['cis'] * sin(2 * phi_k) + ephemeris['cic'] * cos(2 * phi_k)
# Corrected argument of latitude, radius and inclination
uk = phi_k + delta_uk
rk = a * (1 - ephemeris["ecc"] * cos(ek)) + delta_rk
ik = ephemeris["i0"] + delta_ik + ephemeris["idot"] * transmit_time
rk = a * (1 - ephemeris['ecc'] * cos(ek)) + delta_rk
ik = ephemeris['i0'] + delta_ik + ephemeris['idot'] * transmit_time
# Positions in orbital plane
xk_prime = rk * cos(uk)
@@ -313,9 +291,9 @@ def calculate_satellite_position(ephemeris, transmit_time):
# Corrected longitude of ascending node
omega_k = (
ephemeris["omega0"]
+ (ephemeris["omega_dot"] - omega_e_dot) * transmit_time
- omega_e_dot * ephemeris["toe"]
ephemeris['omega0']
+ (ephemeris['omega_dot'] - omega_e_dot) * transmit_time
- omega_e_dot * ephemeris['toe']
)
# Earth-fixed coordinates
@@ -332,10 +310,10 @@ def calculate_satellite_positions(ephemeris, start_time, end_time, step_min=5):
"""
positions = []
current_time = start_time
system = ephemeris["prn"][0]
max_valid_time = 1800 if system == "R" else 14400
system = ephemeris['prn'][0]
max_valid_time = 1800 if system == 'R' else 14400
while current_time <= end_time:
transmit_time = (current_time - ephemeris["epoch"]).total_seconds()
transmit_time = (current_time - ephemeris['epoch']).total_seconds()
if abs(transmit_time) <= max_valid_time:
x, y, z = calculate_satellite_position(ephemeris, transmit_time)
@@ -353,7 +331,7 @@ def ecef_to_az_el(x, y, z, obs_lat, obs_lon, obs_alt):
e_sq = 6.69437999014e-3 # first eccentricity squared
# Convert geodetic coordinates to ECEF
n = a / sqrt(1 - e_sq * sin(obs_lat) ** 2)
n = a / sqrt(1 - e_sq * sin(obs_lat)**2)
obs_x = (n + obs_alt) * cos(obs_lat) * cos(obs_lon)
obs_y = (n + obs_alt) * cos(obs_lat) * sin(obs_lon)
obs_z = (n * (1 - e_sq) + obs_alt) * sin(obs_lat)
@@ -365,16 +343,8 @@ def ecef_to_az_el(x, y, z, obs_lat, obs_lon, obs_alt):
# Convert to local ENU (East, North, Up) coordinates
enu_x = -sin(obs_lon) * dx + cos(obs_lon) * dy
enu_y = (
-sin(obs_lat) * cos(obs_lon) * dx
- sin(obs_lat) * sin(obs_lon) * dy
+ cos(obs_lat) * dz
)
enu_z = (
cos(obs_lat) * cos(obs_lon) * dx
+ cos(obs_lat) * sin(obs_lon) * dy
+ sin(obs_lat) * dz
)
enu_y = -sin(obs_lat) * cos(obs_lon) * dx - sin(obs_lat) * sin(obs_lon) * dy + cos(obs_lat) * dz
enu_z = cos(obs_lat) * cos(obs_lon) * dx + cos(obs_lat) * sin(obs_lon) * dy + sin(obs_lat) * dz
# Calculate azimuth and elevation
azimuth = atan2(enu_x, enu_y)
@@ -387,52 +357,45 @@ def ecef_to_az_el(x, y, z, obs_lat, obs_lon, obs_alt):
return azimuth, elevation
def plot_satellite_tracks(
satellites,
obs_lat,
obs_lon,
obs_alt,
footer_text=None,
filename=None,
show_plot=True,
start_time=None,
end_time=None,
):
def plot_satellite_tracks(satellites, obs_lat, obs_lon, obs_alt,
footer_text=None, filename=None,
show_plot=True, start_time=None,
end_time=None):
"""Plot trajectories for all visible satellites"""
plt.rcParams["font.family"] = "Times New Roman"
fig = plt.figure(figsize=(8, 8))
ax = fig.add_subplot(111, projection="polar")
ax = fig.add_subplot(111, projection='polar')
ax.tick_params(labelsize=16, pad=7)
# Polar plot setup
ax.set_theta_zero_location("N")
ax.set_theta_zero_location('N')
ax.set_theta_direction(-1)
ax.set_ylim(0, 90)
# Elevation ticks
ax.set_yticks(range(0, 91, 15))
ax.set_yticklabels(["90°", "", "60°", "", "30°", "", "0°"], fontsize=14)
ax.set_yticklabels(['90°', '', '60°', '', '30°', '', '0°'], fontsize=14)
# Color scheme by constellation
system_colors = {
"G": "blue", # GPS
"E": "green", # Galileo
"R": "red", # GLONASS
"C": "orange", # BeiDou
"J": "brown", # QZSS
"I": "pink", # IRNSS
"S": "gray", # SBAS
'G': 'blue', # GPS
'E': 'green', # Galileo
'R': 'red', # GLONASS
'C': 'orange', # BeiDou
'J': 'brown', # QZSS
'I': 'pink', # IRNSS
'S': 'gray' # SBAS
}
# System names mapping
system_names = {
"G": "GPS",
"E": "Galileo",
"R": "GLONASS",
"C": "BeiDou",
"J": "QZSS",
"I": "IRNSS",
"S": "SBAS",
'G': 'GPS',
'E': 'Galileo',
'R': 'GLONASS',
'C': 'BeiDou',
'J': 'QZSS',
'I': 'IRNSS',
'S': 'SBAS'
}
# Find which systems are actually present
@@ -440,32 +403,23 @@ def plot_satellite_tracks(
# Plot each satellite
for prn, ephemeris_list in satellites.items():
color = system_colors.get(
prn[0], "purple"
) # Default to purple for unknown systems
color = system_colors.get(prn[0], 'purple') # Default to purple for unknown systems
# Get the most recent ephemeris
if not ephemeris_list:
continue
mid_time = start_time + (end_time - start_time) / 2
prev_eph = [
e for e in ephemeris_list if e["epoch"] <= mid_time
] # Previous ephemeris
prev_eph = [e for e in ephemeris_list if e['epoch'] <= mid_time] # Previous ephemeris
if prev_eph: # Pick the most recent ephemeris before or at the midpoint
ephemeris = max(prev_eph, key=lambda e: e["epoch"])
else: # pick the ephemeris whose epoch is closest in time to the midpoint
ephemeris = min(
ephemeris_list,
key=lambda e: abs((e["epoch"] - mid_time).total_seconds()),
)
ephemeris = max(prev_eph, key=lambda e: e['epoch'])
else: # Pick the ephemeris whose epoch is closest in time to the midpoint
ephemeris = min(ephemeris_list, key=lambda e: abs((e['epoch'] - mid_time).total_seconds()))
# Calculate trajectory
if start_time is None or end_time is None:
all_epochs = sorted(
{e["epoch"] for prn_data in satellites.values() for e in prn_data}
)
all_epochs = sorted({e['epoch'] for prn_data in satellites.values() for e in prn_data})
start_time = min(all_epochs)
end_time = max(all_epochs)
@@ -485,7 +439,7 @@ def plot_satellite_tracks(
r = 90 - np.array(el)
# Plot trajectory
ax.plot(theta, r, "-", color=color, alpha=0.7, linewidth=2.5)
ax.plot(theta, r, '-', color=color, alpha=0.7, linewidth=2.5)
# Add arrow at last point
if len(theta) >= 2: # Need at least 2 points for direction
@@ -496,43 +450,30 @@ def plot_satellite_tracks(
arrow_length_factor = 1.3
extended_theta = theta[-2] + dx * arrow_length_factor
extended_r = r[-2] + dy * arrow_length_factor
ax.annotate(
"",
xytext=(theta[-1], r[-1]),
xy=(extended_theta, extended_r),
arrowprops={
"arrowstyle": "->",
"color": color,
"alpha": 0.9,
"linewidth": 1.5,
"shrinkA": 0,
"shrinkB": 0,
},
)
ax.annotate('',
xytext=(theta[-1], r[-1]),
xy=(extended_theta, extended_r),
arrowprops={
'arrowstyle': '->',
'color': color,
'alpha': 0.9,
'linewidth': 1.5,
'shrinkA': 0,
'shrinkB': 0
})
# Label at midpoint
mid_idx = len(theta) // 2
ax.text(
theta[mid_idx],
r[mid_idx],
prn,
fontsize=12,
ha="center",
va="center",
bbox={"facecolor": "white", "alpha": 0.8, "pad": 2},
)
mid_idx = len(theta)//2
ax.text(theta[mid_idx], r[mid_idx], prn,
fontsize=12, ha='center', va='center',
bbox={"facecolor": "white", "alpha": 0.8, "pad": 2})
# Create legend elements only for present systems
legend_elements = [
plt.Line2D(
[0],
[0],
marker="o",
color="w",
label=f"{system_names[sys]} ({sys})",
markerfacecolor=system_colors[sys],
markersize=10,
)
plt.Line2D([0], [0], marker='o', color='w',
label=f'{system_names[sys]} ({sys})',
markerfacecolor=system_colors[sys],
markersize=10)
for sys in present_systems
]
@@ -540,36 +481,36 @@ def plot_satellite_tracks(
if legend_elements:
ax.legend(
handles=legend_elements,
loc="upper right",
loc='upper right',
bbox_to_anchor=(1.3, 1.1),
fontsize=14,
fontsize=14
)
lat_deg = np.degrees(obs_lat)
lon_deg = np.degrees(obs_lon)
lat_hemisphere = "N" if lat_deg >= 0 else "S"
lon_hemisphere = "E" if lon_deg >= 0 else "W"
lat_hemisphere = 'N' if lat_deg >= 0 else 'S'
lon_hemisphere = 'E' if lon_deg >= 0 else 'W'
plt.title(
f"GNSS skyplot from {abs(lat_deg):.2f}° {lat_hemisphere}, "
f"{abs(lon_deg):.2f}° {lon_hemisphere}",
pad=25,
fontsize=20,
fontsize=20
)
if footer_text:
fig.text(0.42, 0.05, footer_text, ha="center", va="center", fontsize=16)
fig.text(0.42, 0.05, footer_text, ha='center', va='center', fontsize=16)
plt.tight_layout()
if filename:
filename_no_path = Path(filename).name
filename_no_dots = filename_no_path.replace(".", "_")
filename_no_dots = filename_no_path.replace('.', '_')
output_name = f"skyplot_{filename_no_dots}.pdf"
else:
output_name = "skyplot.pdf"
plt.savefig(output_name, format="pdf", bbox_inches="tight")
plt.savefig(output_name, format='pdf', bbox_inches='tight')
print(f"Image saved as {output_name}")
if show_plot:
plt.show()
@@ -581,33 +522,34 @@ def main():
"""Generate the skyplot"""
# Set up argument parser
parser = argparse.ArgumentParser(
description="Generate GNSS skyplot from RINEX navigation file", add_help=False
description='Generate GNSS skyplot from RINEX navigation file',
add_help=False
)
# Add the no-show flag
parser.add_argument(
"--no-show", action="store_true", help="Run without displaying plot window"
'--no-show',
action='store_true',
help='Run without displaying plot window'
)
# Add the observation filename
parser.add_argument(
"--use-obs",
action="store_true",
help="Use corresponding RINEX observation file to bound the skyplot to the receiver time window",
'--use-obs',
action='store_true',
help='Use corresponding RINEX observation file to bound the skyplot to the receiver time window'
)
# Parse known args (this ignores other positional args)
args, remaining_args = parser.parse_known_args()
# Handle help manually
if "-h" in remaining_args or "--help" in remaining_args:
print(
"""
if '-h' in remaining_args or '--help' in remaining_args:
print("""
Usage: python skyplot.py <RINEX_FILE> [LATITUDE] [LONGITUDE] [ALTITUDE] [--use-obs] [--no-show]
Example:
python skyplot.py brdc0010.22n 41.275 1.9876 80.0 --use-obs --no-show
"""
)
""")
sys.exit(0)
if len(remaining_args) < 1:
@@ -644,15 +586,9 @@ Example:
return
# Print summary information
all_epochs = sorted(
list(
set(
e["epoch"]
for prn, ephemerides in satellites.items()
for e in ephemerides
)
)
)
all_epochs = sorted(list(set(
e['epoch'] for prn, ephemerides in satellites.items() for e in ephemerides
)))
print("\nFile contains:")
print(f"- {len(satellites)} unique satellites")
print(f"- {len(all_epochs)} unique epochs")
@@ -666,9 +602,12 @@ Example:
print("\nSatellite systems found:")
for system, count in sorted(system_counts.items()):
system_name = {"G": "GPS", "R": "GLONASS", "E": "Galileo", "C": "BeiDou"}.get(
system, "Unknown"
)
system_name = {
'G': 'GPS',
'R': 'GLONASS',
'E': 'Galileo',
'C': 'BeiDou'
}.get(system, 'Unknown')
print(f"- {system_name} ({system}): {count} satellites")
# Generate the combined skyplot
@@ -679,7 +618,7 @@ Example:
obs_path = None
stem = filename[:-1]
for s in ("O", "o"): # try uppercase then lowercase
for s in ('O', 'o'): # Try uppercase then lowercase
candidate = stem + s
tried.append(candidate)
if Path(candidate).exists():
@@ -690,17 +629,11 @@ Example:
obs_start, obs_end = _read_obs_time_bounds(obs_path)
if obs_start and obs_end:
use_start, use_end = obs_start, obs_end
print(
f"\nObservation window detected from {obs_path}: {use_start} → {use_end}"
)
print(f"\nObservation window detected from {obs_path}: {use_start} → {use_end}")
else:
print(
f"\nWarning: Could not read valid times from {obs_path}. Using NAV span instead."
)
print(f"\nWarning: Could not read valid times from {obs_path}. Using NAV span instead.")
else:
print(
f"\nOBS file not found. Tried: {', '.join(tried)}. Using NAV span instead."
)
print(f"\nOBS file not found. Tried: {', '.join(tried)}. Using NAV span instead.")
# Ensure at least two samples with the default 5-minute step
if (use_end - use_start) < timedelta(minutes=5):
@@ -719,7 +652,7 @@ Example:
filename=filename,
show_plot=not args.no_show,
start_time=use_start,
end_time=use_end,
end_time=use_end
)