mirror of
https://github.com/gnss-sdr/gnss-sdr
synced 2025-11-26 03:54:55 +00:00
695 lines
25 KiB
Python
Executable File
695 lines
25 KiB
Python
Executable File
#!/usr/bin/env python
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"""
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skyplot.py
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Reads a RINEX navigation file and generates a skyplot. Optionally, a RINEX observation file can
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also be read to match the skyplot to the receiver processing time.
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Usage: python skyplot.py <RINEX_NAV_FILE> [observer_lat] [observer_lon] [observer_alt] [--use-obs]
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-----------------------------------------------------------------------------
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GNSS-SDR is a Global Navigation Satellite System software-defined receiver.
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This file is part of GNSS-SDR.
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SPDX-FileCopyrightText: 2025 Carles Fernandez-Prades cfernandez(at)cttc.es
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SPDX-License-Identifier: GPL-3.0-or-later
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-----------------------------------------------------------------------------
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"""
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import argparse
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import re
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import sys
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from datetime import datetime, timedelta
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from math import atan2, cos, sin, sqrt
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from pathlib import Path
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import matplotlib.pyplot as plt
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import numpy as np
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def _read_obs_time_bounds(obs_path):
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"""Return (start_time, end_time) from a RINEX 2/3 OBS file by scanning epoch lines.
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If parsing fails or the file is not OBS, return (None, None).
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"""
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try:
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with open(obs_path, 'r', encoding='utf-8', errors='ignore') as f:
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# Detect OBS in header and skip to END OF HEADER
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is_obs = False
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for line in f:
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if "RINEX VERSION / TYPE" in line:
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# Robust OBS detection:
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# In RINEX 2/3 the file-type letter at col 21 (0-based idx 20)
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tchar = line[20:21]
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if tchar == 'O' or 'OBSERVATION DATA' in line:
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is_obs = True
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if "END OF HEADER" in line:
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break
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if not is_obs:
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return (None, None)
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start_time = None
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end_time = None
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for line in f:
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if not line.strip():
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continue
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if line.startswith('>'): # RINEX 3 epoch line
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yyyy = int(line[2:6]); mm = int(line[7:9]); dd = int(line[10:12])
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hh = int(line[13:15]); mi = int(line[16:18]); ss = float(line[19:29])
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epoch = datetime(yyyy, mm, dd, hh, mi, int(ss), int((ss % 1)*1e6))
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else:
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# RINEX 2 epoch line
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try:
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yy = int(line[1:3]); mm = int(line[4:6]); dd = int(line[7:9])
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hh = int(line[10:12]); mi = int(line[13:15]); ss = float(line[15:26])
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yyyy = 1900 + yy if yy >= 80 else 2000 + yy
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epoch = datetime(yyyy, mm, dd, hh, mi, int(ss), int((ss % 1)*1e6))
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except Exception:
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continue
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if start_time is None or epoch < start_time:
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start_time = epoch
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if end_time is None or epoch > end_time:
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end_time = epoch
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return (start_time, end_time)
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except Exception:
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return (None, None)
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def parse_rinex_float(s):
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"""Parse RINEX formatted float string which may contain D or E exponent and compact spacing"""
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# Handle empty string
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if not s.strip():
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return 0.0
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# Replace D exponent with E (some RINEX files use D instead of E)
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s = s.replace('D', 'E').replace('d', 'e')
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# Handle cases where exponent lacks E (e.g., "12345-3")
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if re.match(r'[+-]?\d+[+-]\d+', s.strip()):
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s = s.replace('+', 'E+').replace('-', 'E-')
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try:
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return float(s)
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except ValueError:
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# Handle cases where the number runs into the next field
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# Try to split at the exponent if present
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if 'E' in s:
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base, exp = s.split('E')[:2]
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# Take first character of exponent if needed
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if exp and exp[0] in '+-' and len(exp) > 1:
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return float(base + 'E' + exp[0] + exp[1:].split()[0])
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return 0.0 # Default if parsing fails
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def read_rinex_nav(filename):
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"""Read RINEX v3.0 navigation file"""
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satellites = {}
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line_number = 0
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with open(filename, 'r', encoding='utf-8') as f:
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# Skip header
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while True:
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line = f.readline()
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line_number += 1
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if not line:
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return satellites # Empty file
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if "END OF HEADER" in line:
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break
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# Read ephemeris data
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current_line = f.readline()
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line_number += 1
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while current_line:
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if len(current_line) < 23:
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current_line = f.readline()
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line_number += 1
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continue
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prn = current_line[:3].strip()
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system = prn[0] # G, R, E, etc.
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try:
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# Parse epoch fields
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year = int(current_line[4:8])
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month = int(current_line[9:11])
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day = int(current_line[12:14])
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hour = int(current_line[15:17])
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minute = int(current_line[18:20])
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second = int(float(current_line[21:23]))
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year += 2000 if year < 80 else 0
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epoch = datetime(year, month, day, hour, minute, second)
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# Read the next lines
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lines = [current_line]
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line_count = 4 if system == 'R' else 7
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for _ in range(line_count):
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next_line = f.readline()
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line_number += 1
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if not next_line:
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break
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lines.append(next_line)
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if len(lines) < line_count + 1:
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current_line = f.readline()
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line_number += 1
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continue
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if system == 'R': # GLONASS specific parsing
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ephemeris = {
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'prn': prn,
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'epoch': epoch,
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'sv_clock_bias': parse_rinex_float(lines[0][23:42]),
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'sv_relative_freq_bias': parse_rinex_float(lines[0][42:61]),
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'message_frame_time': parse_rinex_float(lines[0][61:80]),
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'x': parse_rinex_float(lines[1][4:23]), # Position (km)
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'x_vel': parse_rinex_float(lines[1][23:42]), # Velocity (km/s)
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'x_acc': parse_rinex_float(lines[1][42:61]),
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'health': parse_rinex_float(lines[1][61:80]),
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'y': parse_rinex_float(lines[2][4:23]),
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'y_vel': parse_rinex_float(lines[2][23:42]),
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'y_acc': parse_rinex_float(lines[2][42:61]),
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'freq_num': parse_rinex_float(lines[2][61:80]),
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'z': parse_rinex_float(lines[3][4:23]),
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'z_vel': parse_rinex_float(lines[3][23:42]),
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'z_acc': parse_rinex_float(lines[3][42:61]),
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'age': parse_rinex_float(lines[3][61:80])
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}
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else:
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# Parse all ephemeris parameters
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ephemeris = {
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'prn': prn,
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'epoch': epoch,
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'sv_clock_bias': parse_rinex_float(lines[0][23:42]),
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'sv_clock_drift': parse_rinex_float(lines[0][42:61]),
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'sv_clock_drift_rate': parse_rinex_float(lines[0][61:80]),
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'iode': parse_rinex_float(lines[1][4:23]),
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'crs': parse_rinex_float(lines[1][23:42]),
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'delta_n': parse_rinex_float(lines[1][42:61]),
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'm0': parse_rinex_float(lines[1][61:80]),
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'cuc': parse_rinex_float(lines[2][4:23]),
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'ecc': parse_rinex_float(lines[2][23:42]),
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'cus': parse_rinex_float(lines[2][42:61]),
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'sqrt_a': parse_rinex_float(lines[2][61:80]),
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'toe': parse_rinex_float(lines[3][4:23]),
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'cic': parse_rinex_float(lines[3][23:42]),
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'omega0': parse_rinex_float(lines[3][42:61]),
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'cis': parse_rinex_float(lines[3][61:80]),
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'i0': parse_rinex_float(lines[4][4:23]),
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'crc': parse_rinex_float(lines[4][23:42]),
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'omega': parse_rinex_float(lines[4][42:61]),
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'omega_dot': parse_rinex_float(lines[4][61:80]),
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'idot': parse_rinex_float(lines[5][4:23]),
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'codes_l2': parse_rinex_float(lines[5][23:42]),
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'gps_week': parse_rinex_float(lines[5][42:61]),
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'l2p_flag': parse_rinex_float(lines[5][61:80]),
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'sv_accuracy': parse_rinex_float(lines[6][4:23]),
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'sv_health': parse_rinex_float(lines[6][23:42]),
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'tgd': parse_rinex_float(lines[6][42:61]),
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'iodc': parse_rinex_float(lines[6][61:80]),
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'transmission_time': parse_rinex_float(lines[7][4:23]),
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'fit_interval': (
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parse_rinex_float(lines[7][23:42])) if len(lines[7]) > 23 else 0.0
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}
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if prn not in satellites:
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satellites[prn] = []
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satellites[prn].append(ephemeris)
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except (ValueError, IndexError) as e:
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print(f"\nError in file {filename} at line {line_number}:")
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print(f" PRN: {prn}")
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print(f" Line content: {current_line.strip()}")
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print(f" Error type: {type(e).__name__}")
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print(f" Error details: {str(e)}")
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print("Skipping to next satellite block...\n")
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# Skip to next block by reading until next PRN
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while current_line and not current_line.startswith(prn[0]):
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current_line = f.readline()
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line_number += 1
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continue
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current_line = f.readline()
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line_number += 1
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return satellites
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def calculate_satellite_position(ephemeris, transmit_time):
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"""Calculate satellite position in ECEF coordinates at given transmission time"""
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system = ephemeris['prn'][0]
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if system == 'R': # GLONASS - use position + velocity * time
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dt = transmit_time
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# Convert km to meters
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xk = (ephemeris['x'] + ephemeris['x_vel'] * dt + 0.5 * ephemeris['x_acc'] * dt**2) * 1000
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yk = (ephemeris['y'] + ephemeris['y_vel'] * dt + 0.5 * ephemeris['y_acc'] * dt**2) * 1000
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zk = (ephemeris['z'] + ephemeris['z_vel'] * dt + 0.5 * ephemeris['z_acc'] * dt**2) * 1000
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else:
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# Constants
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mu = 3.986005e14 # Earth's gravitational constant (m^3/s^2)
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omega_e_dot = 7.2921151467e-5 # Earth rotation rate (rad/s)
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# Semi-major axis
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a = ephemeris['sqrt_a'] ** 2
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# Corrected mean motion
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n0 = sqrt(mu / (a ** 3))
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n = n0 + ephemeris['delta_n']
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# Mean anomaly
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mk = ephemeris['m0'] + n * transmit_time
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# Solve Kepler's equation for eccentric anomaly (Ek)
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ek = mk
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for _ in range(10):
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ek_old = ek
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ek = mk + ephemeris['ecc'] * sin(ek)
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if abs(ek - ek_old) < 1e-12:
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break
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# True anomaly
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nu_k = atan2(sqrt(1 - ephemeris['ecc']**2) * sin(ek), cos(ek) - ephemeris['ecc'])
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# Argument of latitude
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phi_k = nu_k + ephemeris['omega']
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# Second harmonic perturbations
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delta_uk = ephemeris['cus'] * sin(2 * phi_k) + ephemeris['cuc'] * cos(2 * phi_k)
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delta_rk = ephemeris['crs'] * sin(2 * phi_k) + ephemeris['crc'] * cos(2 * phi_k)
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delta_ik = ephemeris['cis'] * sin(2 * phi_k) + ephemeris['cic'] * cos(2 * phi_k)
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# Corrected argument of latitude, radius and inclination
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uk = phi_k + delta_uk
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rk = a * (1 - ephemeris['ecc'] * cos(ek)) + delta_rk
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ik = ephemeris['i0'] + delta_ik + ephemeris['idot'] * transmit_time
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# Positions in orbital plane
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xk_prime = rk * cos(uk)
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yk_prime = rk * sin(uk)
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# Corrected longitude of ascending node
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omega_k = (
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ephemeris['omega0']
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+ (ephemeris['omega_dot'] - omega_e_dot) * transmit_time
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- omega_e_dot * ephemeris['toe']
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)
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# Earth-fixed coordinates
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xk = xk_prime * cos(omega_k) - yk_prime * cos(ik) * sin(omega_k)
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yk = xk_prime * sin(omega_k) + yk_prime * cos(ik) * cos(omega_k)
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zk = yk_prime * sin(ik)
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return xk, yk, zk
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def calculate_satellite_positions(ephemeris, start_time, end_time, step_min=5):
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"""Generate multiple positions over time for a single satellite
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between start_time and end_time.
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"""
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positions = []
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current_time = start_time
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system = ephemeris['prn'][0]
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max_valid_time = 1800 if system == 'R' else 14400
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while current_time <= end_time:
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transmit_time = (current_time - ephemeris['epoch']).total_seconds()
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if abs(transmit_time) <= max_valid_time:
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x, y, z = calculate_satellite_position(ephemeris, transmit_time)
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positions.append((current_time, x, y, z))
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current_time += timedelta(minutes=step_min)
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return positions
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def ecef_to_az_el(x, y, z, obs_lat, obs_lon, obs_alt):
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"""Convert ECEF coordinates to azimuth and elevation"""
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# WGS-84 parameters
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a = 6378137.0 # semi-major axis
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e_sq = 6.69437999014e-3 # first eccentricity squared
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# Convert geodetic coordinates to ECEF
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n = a / sqrt(1 - e_sq * sin(obs_lat)**2)
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obs_x = (n + obs_alt) * cos(obs_lat) * cos(obs_lon)
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obs_y = (n + obs_alt) * cos(obs_lat) * sin(obs_lon)
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obs_z = (n * (1 - e_sq) + obs_alt) * sin(obs_lat)
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# Vector from observer to satellite
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dx = x - obs_x
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dy = y - obs_y
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dz = z - obs_z
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# Convert to local ENU (East, North, Up) coordinates
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enu_x = -sin(obs_lon) * dx + cos(obs_lon) * dy
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enu_y = -sin(obs_lat) * cos(obs_lon) * dx - sin(obs_lat) * sin(obs_lon) * dy + cos(obs_lat) * dz
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enu_z = cos(obs_lat) * cos(obs_lon) * dx + cos(obs_lat) * sin(obs_lon) * dy + sin(obs_lat) * dz
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# Calculate azimuth and elevation
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azimuth = atan2(enu_x, enu_y)
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elevation = atan2(enu_z, sqrt(enu_x**2 + enu_y**2))
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# Convert to degrees and adjust azimuth to 0-360
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azimuth = np.degrees(azimuth) % 360
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elevation = np.degrees(elevation)
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return azimuth, elevation
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def plot_satellite_tracks(satellites, obs_lat, obs_lon, obs_alt,
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footer_text=None, filename=None,
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show_plot=True, start_time=None,
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end_time=None, elev_mask=5.0):
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"""Plot trajectories for all visible satellites"""
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plt.rcParams["font.family"] = "Times New Roman"
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fig = plt.figure(figsize=(8, 8))
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ax = fig.add_subplot(111, projection='polar')
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ax.tick_params(labelsize=16, pad=7)
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# Polar plot setup
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ax.set_theta_zero_location('N')
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ax.set_theta_direction(-1)
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ax.set_ylim(0, 90)
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# Elevation ticks
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ax.set_yticks(range(0, 91, 15))
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ax.set_yticklabels(['90°', '', '60°', '', '30°', '', '0°'], fontsize=14)
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# Color scheme by constellation
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system_colors = {
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'G': 'blue', # GPS
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'E': 'green', # Galileo
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'R': 'red', # GLONASS
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'C': 'orange', # BeiDou
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'J': 'brown', # QZSS
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'I': 'pink', # IRNSS
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'S': 'gray' # SBAS
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}
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# System names mapping
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system_names = {
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'G': 'GPS',
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'E': 'Galileo',
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'R': 'GLONASS',
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'C': 'BeiDou',
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'J': 'QZSS',
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'I': 'IRNSS',
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'S': 'SBAS'
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}
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# Find which systems are actually present
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present_systems = {prn[0] for prn in satellites.keys() if prn[0] in system_colors}
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# Plot each satellite
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for prn, ephemeris_list in satellites.items():
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color = system_colors.get(prn[0], 'purple') # Default to purple for unknown systems
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if not ephemeris_list:
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continue
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mid_time = start_time + (end_time - start_time) / 2
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prev_eph = [e for e in ephemeris_list if e['epoch'] <= mid_time]
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if prev_eph:
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ephemeris = max(prev_eph, key=lambda e: e['epoch'])
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else:
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ephemeris = min(ephemeris_list, key=lambda e: abs((e['epoch'] - mid_time).total_seconds()))
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if start_time is None or end_time is None:
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all_epochs = sorted({e['epoch'] for prn_data in satellites.values() for e in prn_data})
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start_time = min(all_epochs)
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end_time = max(all_epochs)
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positions = calculate_satellite_positions(ephemeris, start_time, end_time)
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# Split into visible segments
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segments = []
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current_seg_az = []
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current_seg_el = []
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for _, x, y, z in positions:
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azimuth, elevation = ecef_to_az_el(x, y, z, obs_lat, obs_lon, obs_alt)
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if elevation > elev_mask:
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current_seg_az.append(azimuth)
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current_seg_el.append(elevation)
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else:
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if len(current_seg_az) > 1:
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segments.append((current_seg_az, current_seg_el))
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current_seg_az, current_seg_el = [], []
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if len(current_seg_az) > 1:
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segments.append((current_seg_az, current_seg_el))
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# Plot each segment separately
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for az_seg, el_seg in segments:
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theta = np.radians(az_seg)
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r = 90 - np.array(el_seg)
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|
ax.plot(theta, r, '-', color=color, alpha=0.7, linewidth=2.5)
|
|
|
|
# Arrow at end
|
|
if len(theta) >= 2:
|
|
dx = theta[-1] - theta[-2]
|
|
dy = r[-1] - r[-2]
|
|
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
|
|
})
|
|
|
|
# Label at midpoint of the segment
|
|
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})
|
|
|
|
# Legend 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)
|
|
for sys in present_systems
|
|
]
|
|
if legend_elements:
|
|
ax.legend(handles=legend_elements,
|
|
loc='upper right',
|
|
bbox_to_anchor=(1.3, 1.1),
|
|
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'
|
|
|
|
plt.title(
|
|
f"GNSS skyplot from {abs(lat_deg):.2f}° {lat_hemisphere}, "
|
|
f"{abs(lon_deg):.2f}° {lon_hemisphere}",
|
|
pad=25,
|
|
fontsize=20
|
|
)
|
|
|
|
if footer_text:
|
|
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('.', '_')
|
|
output_name = f"skyplot_{filename_no_dots}.pdf"
|
|
else:
|
|
output_name = "skyplot.pdf"
|
|
|
|
plt.savefig(output_name, format='pdf', bbox_inches='tight')
|
|
print(f"Image saved as {output_name}")
|
|
if show_plot:
|
|
plt.show()
|
|
else:
|
|
plt.close()
|
|
|
|
|
|
def main():
|
|
"""Generate the skyplot"""
|
|
# Set system names and codes
|
|
system_name_to_code = {
|
|
'GPS': 'G',
|
|
'GLONASS': 'R',
|
|
'GALILEO': 'E',
|
|
'BEIDOU': 'C',
|
|
'QZSS': 'J',
|
|
'IRNSS': 'I',
|
|
'SBAS': 'S'
|
|
}
|
|
|
|
# Set up argument parser
|
|
parser = argparse.ArgumentParser(
|
|
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'
|
|
)
|
|
# Add the use-obs flag
|
|
parser.add_argument(
|
|
'--use-obs',
|
|
action='store_true',
|
|
help='Use corresponding RINEX observation file to bound the skyplot to the receiver time window'
|
|
)
|
|
# Add the elev-mask flag.
|
|
parser.add_argument(
|
|
'--elev-mask', type=float, default=5.0,
|
|
help='Elevation mask in degrees for plotting satellite tracks (default: 5°)'
|
|
)
|
|
# Add the system flag.
|
|
parser.add_argument(
|
|
'--system',
|
|
nargs='+',
|
|
help='Only plot satellites from these systems (e.g., G R E or GPS Galileo GLONASS)'
|
|
)
|
|
# 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("""
|
|
Usage: python skyplot.py <RINEX_FILE> [LATITUDE] [LONGITUDE] [ALTITUDE] [--use-obs] [--elev-mask] [--system ...] [--no-show]
|
|
|
|
Example:
|
|
python skyplot.py brdc0010.22n 41.275 1.9876 80.0 --use-obs --no-show --elev-mask=10 --system GPS Galileo
|
|
""")
|
|
sys.exit(0)
|
|
|
|
if len(remaining_args) < 1:
|
|
print("Error: RINEX file required")
|
|
sys.exit(1)
|
|
|
|
filename = remaining_args[0]
|
|
|
|
# Default observer location (Castelldefels, Barcelona, Spain)
|
|
obs_lat = np.radians(41.2750)
|
|
obs_lon = np.radians(1.9876)
|
|
obs_alt = 80.0
|
|
|
|
# Override with command line arguments if provided
|
|
if len(remaining_args) >= 4:
|
|
try:
|
|
obs_lat = np.radians(float(remaining_args[1]))
|
|
obs_lon = np.radians(float(remaining_args[2]))
|
|
if len(remaining_args) >= 5:
|
|
obs_alt = float(remaining_args[3])
|
|
except ValueError:
|
|
print("Invalid observer coordinates. Using defaults.")
|
|
|
|
# Read RINEX file
|
|
print(f"Reading {filename}...")
|
|
try:
|
|
satellites = read_rinex_nav(filename)
|
|
except FileNotFoundError:
|
|
print(f"Error: File '{filename}' not found.")
|
|
return
|
|
|
|
if not satellites:
|
|
print("No satellite data found in the file.")
|
|
return
|
|
|
|
if args.system:
|
|
systems_upper = set()
|
|
for s in args.system:
|
|
s_upper = s.upper()
|
|
if s_upper in system_name_to_code:
|
|
systems_upper.add(system_name_to_code[s_upper])
|
|
else:
|
|
systems_upper.add(s_upper) # Assume user passed the code
|
|
|
|
satellites = {prn: eph_list for prn, eph_list in satellites.items() if prn[0].upper() in systems_upper}
|
|
|
|
if not satellites:
|
|
print(f"No satellites found for systems: {', '.join(sorted(systems_upper))}")
|
|
return
|
|
|
|
# Print summary information
|
|
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")
|
|
print(f"- From {all_epochs[0]} to {all_epochs[-1]}")
|
|
|
|
# Calculate and print satellite counts by system
|
|
system_counts = {}
|
|
for prn in satellites:
|
|
system = prn[0]
|
|
system_counts[system] = system_counts.get(system, 0) + 1
|
|
|
|
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')
|
|
print(f"- {system_name} ({system}): {count} satellites")
|
|
|
|
# Generate the combined skyplot
|
|
# Time window: OBS bounds if provided; else NAV span
|
|
use_start, use_end = all_epochs[0], all_epochs[-1]
|
|
if args.use_obs:
|
|
tried = []
|
|
obs_path = None
|
|
stem = filename[:-1]
|
|
|
|
for s in ('O', 'o'): # Try uppercase then lowercase
|
|
candidate = stem + s
|
|
tried.append(candidate)
|
|
if Path(candidate).exists():
|
|
obs_path = candidate
|
|
break
|
|
|
|
if obs_path:
|
|
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}")
|
|
else:
|
|
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.")
|
|
|
|
# Ensure at least two samples with the default 5-minute step
|
|
if (use_end - use_start) < timedelta(minutes=5):
|
|
use_end = use_start + timedelta(minutes=5)
|
|
|
|
# Generate the combined skyplot
|
|
print("\nGenerating skyplot...")
|
|
footer = f"From {use_start} to {use_end} UTC"
|
|
|
|
plot_satellite_tracks(
|
|
satellites,
|
|
obs_lat,
|
|
obs_lon,
|
|
obs_alt,
|
|
footer_text=footer,
|
|
filename=filename,
|
|
show_plot=not args.no_show,
|
|
start_time=use_start,
|
|
end_time=use_end,
|
|
elev_mask=args.elev_mask
|
|
)
|
|
|
|
|
|
if __name__ == "__main__":
|
|
main()
|