mirror of
https://github.com/gnss-sdr/gnss-sdr
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1451 lines
51 KiB
Python
Executable File
1451 lines
51 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
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observation file can also be read to match the skyplot to the receiver
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processing time.
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Usage:
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skyplot.py <RINEX_NAV_FILE> [observer_lat] [observer_lon] [observer_alt]
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[--elev-mask ELEV_MASK]
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[--format {pdf,eps,jpg,png,svg}]
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[--no-show]
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[--system SYSTEM [SYSTEM ...]]
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[--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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from typing import Any, Dict, List, Tuple, Optional
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try:
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import matplotlib.pyplot as plt
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import numpy as np
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except ImportError:
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print("Error: This script requires matplotlib and numpy.")
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print("Install them with: pip install matplotlib numpy")
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sys.exit(1)
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__version__ = "1.0.0"
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# Default position: Castelldefels, Barcelona
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DEFAULT_LAT = 41.275
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DEFAULT_LON = 1.9876
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DEFAULT_ALT = 80.0
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def read_obs_time_bounds(
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obs_path: str,
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) -> Tuple[Optional[datetime], Optional[datetime]]:
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"""
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Return (start_time, end_time) from a RINEX observation file (v2/3/4)
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by scanning epoch lines. If parsing fails or the file is not OBS, return (None, None).
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"""
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start_time = None
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end_time = None
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try:
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obs_file = Path(obs_path)
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if not obs_file.exists():
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return (None, None)
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with obs_file.open("r", encoding="utf-8", errors="ignore") as f:
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# --- Detect OBS file in 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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file_type = line[20:21].upper()
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if file_type == "O" or "OBSERVATION DATA" in line.upper():
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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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# --- Scan for epoch lines ---
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for line in f:
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line = line.rstrip()
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if not line:
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continue
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try:
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if line.startswith(">"): # RINEX 3/4 epoch line
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yyyy = int(line[2:6])
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mm = int(line[7:9])
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dd = int(line[10:12])
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hh = int(line[13:15])
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mi = int(line[16:18])
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ss = float(line[19:29])
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else: # RINEX 2 epoch line
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yy = int(line[1:3])
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mm = int(line[4:6])
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dd = int(line[7:9])
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hh = int(line[10:12])
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mi = int(line[13:15])
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ss = float(line[15:26])
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yyyy = 1900 + yy if yy >= 80 else 2000 + yy
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epoch = datetime(
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yyyy, mm, dd, hh, mi, int(ss), int((ss % 1) * 1e6)
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)
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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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except Exception:
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# Skip malformed lines
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continue
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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 find_obs_for_nav(nav_file: str) -> Optional[str]:
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"""
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Find the corresponding RINEX observation file for a given navigation file.
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This function attempts to locate the appropriate observation (OBS) file that
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corresponds to a given navigation (NAV) file by applying standard RINEX naming
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conventions across versions 2, 3, and 4.
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Parameters
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----------
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nav_file : str
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Path to the RINEX navigation file. The function will search for a
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corresponding observation file using various naming patterns.
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Returns
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-------
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Optional[str]
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Path to the found observation file if successful, None otherwise.
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Also prints the list of attempted file paths if no match is found.
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"""
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nav_path = Path(nav_file)
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tried = []
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stem = nav_path.stem
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suffix = nav_path.suffix
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# --- RINEX v2 names: replace last letter of extension with 'O' or 'o'
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if suffix and suffix[-1].isalpha():
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for o_type in ("O", "o"):
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candidate = nav_path.with_suffix(suffix[:-1] + o_type)
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tried.append(str(candidate))
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if candidate.exists():
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return str(candidate)
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# --- RINEX v3/v4 names: handle standard extensions and common modifiers
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gnss_patterns = [
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# Mixed constellations
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("_MN", "_MO"),
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("_mn", "_mo"),
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("_MM", "_MO"),
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("_mm", "_mo"),
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("_MR", "_MO"),
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("_mr", "_mo"),
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# Individual constellations
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("_GN", "_GO"), # GPS
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("_gn", "_go"),
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("_RN", "_RO"), # GLONASS
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("_rn", "_ro"),
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("_EN", "_EO"), # Galileo
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("_en", "_eo"),
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("_CN", "_CO"), # BeiDou
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("_cn", "_co"),
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("_JN", "_JO"), # QZSS
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("_jn", "_jo"),
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("_IN", "_IO"), # IRNSS
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("_in", "_io"),
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("_SN", "_SO"), # SBAS
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("_sn", "_so"),
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]
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for nav_pattern, obs_pattern in gnss_patterns:
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if nav_pattern in stem:
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# Direct replacement (e.g., _MN -> _MO)
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candidate = nav_path.with_name(
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stem.replace(nav_pattern, obs_pattern) + suffix
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)
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tried.append(str(candidate))
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if candidate.exists():
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return str(candidate)
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# Handle sampling rate patterns (e.g., _MN -> _30S_MO)
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sampling_rates = [
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"_30S",
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"_15S",
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"_01S",
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"_05S",
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"_30s",
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"_15s",
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"_01s",
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"_05s",
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]
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for rate in sampling_rates:
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candidate = nav_path.with_name(
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stem.replace(nav_pattern, rate + obs_pattern) + suffix
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)
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tried.append(str(candidate))
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if candidate.exists():
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return str(candidate)
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# Also try with common observation extensions
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for obs_ext in [
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".rnx",
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".obs",
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".OBS",
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".22O",
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".23O",
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".24O",
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".25O",
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]:
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if suffix != obs_ext:
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candidate = nav_path.with_name(
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stem.replace(nav_pattern, obs_pattern) + obs_ext
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)
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tried.append(str(candidate))
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if candidate.exists():
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return str(candidate)
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# --- Additional patterns for files with sampling rate modifiers before constellation code
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sampling_rates = [
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"_30S",
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"_15S",
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"_01S",
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"_05S",
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"_30s",
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"_15s",
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"_01s",
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"_05s",
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"_01H",
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"_1H",
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"_01h",
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"_1h",
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]
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for rate in sampling_rates:
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if rate in stem:
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# Check if this is a navigation file with sampling rate + _MN/_GN/etc.
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for nav_suffix in [
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"_MN",
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"_GN",
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"_RN",
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"_EN",
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"_CN",
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"_JN",
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"_IN",
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"_SN",
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"_mn",
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"_gn",
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"_rn",
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"_en",
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"_cn",
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"_jn",
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"_in",
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"_sn",
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]:
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if rate + nav_suffix in stem:
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# Replace navigation with observation (e.g., _30S_MN -> _30S_MO)
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candidate = nav_path.with_name(
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stem.replace(
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rate + nav_suffix,
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rate
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+ nav_suffix.replace("N", "O").replace("n", "o"),
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)
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+ suffix
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)
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tried.append(str(candidate))
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if candidate.exists():
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return str(candidate)
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# Also try without sampling rate (e.g., _30S_MN -> _MO)
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candidate = nav_path.with_name(
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stem.replace(
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rate + nav_suffix,
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nav_suffix.replace("N", "O").replace("n", "o"),
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)
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+ suffix
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)
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tried.append(str(candidate))
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if candidate.exists():
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return str(candidate)
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print(f"OBS file not found. Tried: {', '.join(tried)}.")
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return None
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def ecef_to_geodetic(
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x: float, y: float, z: float
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) -> Tuple[float, float, float]:
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"""Convert ECEF (X, Y, Z) [m] to (lat [°], lon [°], h [m])."""
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# WGS84 constants
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a = 6378137.0 # semi-major axis
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f = 1 / 298.257223563
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e2 = f * (2 - f)
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lon = atan2(y, x)
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r = sqrt(x * x + y * y)
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lat = atan2(z, r * (1 - e2)) # initial guess
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# Iterative improvement
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for _ in range(5):
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N = a / sqrt(1 - e2 * sin(lat) ** 2)
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h = r / cos(lat) - N
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lat = atan2(z, r * (1 - e2 * (N / (N + h))))
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N = a / sqrt(1 - e2 * sin(lat) ** 2)
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h = r / cos(lat) - N
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return np.degrees(lat), np.degrees(lon), h
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def get_approx_position_from_obs(
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obs_file: str,
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) -> Optional[Tuple[float, float, float]]:
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"""Read APPROX POSITION XYZ from an OBS RINEX file header.
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Returns (lat, lon, h) in degrees/meters or None if not valid."""
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try:
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with open(obs_file, "r") as f:
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for line in f:
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if "APPROX POSITION XYZ" in line:
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parts = line.split()
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if len(parts) >= 3:
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try:
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x, y, z = map(float, parts[0:3])
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except ValueError:
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return None
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# Check if position is valid (not all zeros)
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if abs(x) < 1e-6 and abs(y) < 1e-6 and abs(z) < 1e-6:
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return None
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# Convert ECEF → geodetic
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return ecef_to_geodetic(x, y, z)
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return None
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except OSError:
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return None
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def parse_rinex_float(s: str) -> float:
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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_header(filename: str) -> Tuple[str, str]:
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"""Return (version_str, file_type_char) from the 'RINEX VERSION / TYPE' header line."""
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with open(filename, "r", encoding="utf-8", errors="ignore") as f:
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for line in f:
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if "RINEX VERSION / TYPE" in line:
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version = line[0:9].strip() # F9.2 in v2/v3/v4
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# 'N' (GPS nav v2), 'G' (GLO nav v2), 'H' (GEO/SBAS v2), 'N' in v3/4 too
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ftype = line[20:21].upper()
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return version, ftype
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if "END OF HEADER" in line:
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break
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return "", ""
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def read_rinex_nav(filename: str) -> Dict[str, List[Dict[str, Any]]]:
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"""
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Read RINEX v2/v3/v4 navigation file into a dict { 'Gxx': [eph...], 'Rxx': [...], 'Sxxx': [...] }.
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"""
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version_str, ftype = read_rinex_header(filename)
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is_v2 = version_str.startswith("2")
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satellites = {}
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line_number = 0
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with open(filename, "r", encoding="utf-8", errors="ignore") 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
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if "END OF HEADER" in line:
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break
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current_line = f.readline()
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||
line_number += 1
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||
# ----------------------------
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||
# RINEX 2.10 / 2.11 parsing
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||
# ----------------------------
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if is_v2:
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# File type: 'N' (GPS), 'G' (GLONASS), 'H' (GEO/SBAS)
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v2_system = ftype # keep original char
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||
while current_line:
|
||
# Skip empties
|
||
if not current_line.strip():
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current_line = f.readline()
|
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line_number += 1
|
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continue
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||
|
||
try:
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||
# --- First record line: PRN/EPOCH/CLOCK --------------------
|
||
# Formats per RINEX 2.11 Table A4 (GPS) and Table A11 (GLONASS)
|
||
prn_num = int(current_line[0:2])
|
||
yy = int(current_line[3:5])
|
||
mm = int(current_line[6:8])
|
||
dd = int(current_line[9:11])
|
||
hh = int(current_line[12:14])
|
||
mi = int(current_line[15:17])
|
||
ss = float(current_line[18:23])
|
||
|
||
# Year mapping: 80–99 => 1980–1999, 00–79 => 2000–2079
|
||
yyyy = 1900 + yy if yy >= 80 else 2000 + yy
|
||
epoch = datetime(
|
||
yyyy, mm, dd, hh, mi, int(ss), int((ss % 1) * 1e6)
|
||
)
|
||
|
||
# Map PRN to 'Gxx' / 'Rxx' / 'Sxxx'
|
||
if v2_system == "N": # GPS nav
|
||
prn = f"G{prn_num:02d}"
|
||
elif v2_system == "G": # GLONASS nav
|
||
prn = f"R{prn_num:02d}"
|
||
elif v2_system == "H": # GEO/SBAS nav (PRN-100 in file)
|
||
prn = f"S{prn_num + 100:03d}"
|
||
else:
|
||
# Unknown v2 type; skip
|
||
current_line = f.readline()
|
||
line_number += 1
|
||
continue
|
||
|
||
# Collect the lines of this ephemeris block:
|
||
lines = [current_line]
|
||
|
||
if v2_system == "G" or v2_system == "H":
|
||
# GLONASS & GEO blocks: 3 more lines (Tables A11/A16) -> total 4 records
|
||
needed = 3
|
||
else:
|
||
# GPS v2 block: 7 more lines (Table A4) -> total 8 records
|
||
needed = 7
|
||
|
||
for _ in range(needed):
|
||
next_line = f.readline()
|
||
line_number += 1
|
||
if not next_line:
|
||
break
|
||
lines.append(next_line)
|
||
|
||
if len(lines) < needed + 1:
|
||
current_line = f.readline()
|
||
line_number += 1
|
||
continue
|
||
|
||
if v2_system == "N":
|
||
# GPS
|
||
ephemeris = {
|
||
"prn": prn,
|
||
"epoch": epoch,
|
||
"sv_clock_bias": parse_rinex_float(
|
||
lines[0][23:41]
|
||
),
|
||
"sv_clock_drift": parse_rinex_float(
|
||
lines[0][41:61]
|
||
),
|
||
"sv_clock_drift_rate": parse_rinex_float(
|
||
lines[0][61:80]
|
||
),
|
||
"iode": parse_rinex_float(lines[1][4:22]),
|
||
"crs": parse_rinex_float(lines[1][22:41]),
|
||
"delta_n": parse_rinex_float(lines[1][41:60]),
|
||
"m0": parse_rinex_float(lines[1][61:80]),
|
||
"cuc": parse_rinex_float(lines[2][4:22]),
|
||
"ecc": parse_rinex_float(lines[2][22:41]),
|
||
"cus": parse_rinex_float(lines[2][41:60]),
|
||
"sqrt_a": parse_rinex_float(lines[2][60:80]),
|
||
"toe": parse_rinex_float(lines[3][4:22]),
|
||
"cic": parse_rinex_float(lines[3][22:41]),
|
||
"omega0": parse_rinex_float(lines[3][41:60]),
|
||
"cis": parse_rinex_float(lines[3][60:80]),
|
||
"i0": parse_rinex_float(lines[4][4:22]),
|
||
"crc": parse_rinex_float(lines[4][22:41]),
|
||
"omega": parse_rinex_float(lines[4][41:60]),
|
||
"omega_dot": parse_rinex_float(lines[4][60:80]),
|
||
"idot": parse_rinex_float(lines[5][4:22]),
|
||
"codes_l2": parse_rinex_float(lines[5][22:41]),
|
||
"gps_week": parse_rinex_float(lines[5][41:61]),
|
||
"l2p_flag": parse_rinex_float(lines[5][61:80]),
|
||
"sv_accuracy": parse_rinex_float(lines[6][4:22]),
|
||
"sv_health": parse_rinex_float(lines[6][22:41]),
|
||
"tgd": parse_rinex_float(lines[6][41:61]),
|
||
"iodc": parse_rinex_float(lines[6][61:80]),
|
||
"transmission_time": parse_rinex_float(
|
||
lines[7][4:22]
|
||
)
|
||
if len(lines) > 7
|
||
else None,
|
||
"fit_interval": parse_rinex_float(lines[7][22:41])
|
||
if len(lines) > 7
|
||
else None,
|
||
"extra": lines[8:],
|
||
}
|
||
elif v2_system == "H":
|
||
# GEO/SBAS (Table A16)
|
||
ephemeris = {
|
||
"prn": prn,
|
||
"epoch": epoch,
|
||
"sv_clock_bias": parse_rinex_float(
|
||
lines[0][23:41]
|
||
),
|
||
"sv_clock_drift": parse_rinex_float(
|
||
lines[0][41:61]
|
||
),
|
||
"sv_clock_drift_rate": parse_rinex_float(
|
||
lines[0][61:80]
|
||
),
|
||
"x": parse_rinex_float(lines[1][4:22]),
|
||
"x_vel": parse_rinex_float(lines[1][22:41]),
|
||
"x_acc": parse_rinex_float(lines[1][41:60]),
|
||
"health": parse_rinex_float(lines[1][60:80]),
|
||
"y": parse_rinex_float(lines[2][4:22]),
|
||
"y_vel": parse_rinex_float(lines[2][22:41]),
|
||
"y_acc": parse_rinex_float(lines[2][41:61]),
|
||
"z": parse_rinex_float(lines[3][4:22]),
|
||
"z_vel": parse_rinex_float(lines[3][21:41]),
|
||
"z_acc": parse_rinex_float(lines[3][41:61]),
|
||
"extra": lines[4:],
|
||
}
|
||
elif v2_system == "G":
|
||
# GLONASS
|
||
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][4:22]),
|
||
"x_vel": parse_rinex_float(lines[1][22:41]),
|
||
"x_acc": parse_rinex_float(lines[1][41:60]),
|
||
"health": parse_rinex_float(lines[1][60:80]),
|
||
"y": parse_rinex_float(lines[2][4:22]),
|
||
"y_vel": parse_rinex_float(lines[2][22:41]),
|
||
"y_acc": parse_rinex_float(lines[2][41:60]),
|
||
"freq_num": parse_rinex_float(lines[2][60:80]),
|
||
"z": parse_rinex_float(lines[3][4:22]),
|
||
"z_vel": parse_rinex_float(lines[3][22:41]),
|
||
"z_acc": parse_rinex_float(lines[3][41:60]),
|
||
"age": parse_rinex_float(lines[3][60:80]),
|
||
"extra": lines[4:],
|
||
}
|
||
else:
|
||
ephemeris = None
|
||
|
||
if ephemeris:
|
||
satellites.setdefault(prn, []).append(ephemeris)
|
||
|
||
except (ValueError, IndexError):
|
||
# Skip malformed block; advance
|
||
current_line = f.readline()
|
||
line_number += 1
|
||
continue
|
||
|
||
current_line = f.readline()
|
||
line_number += 1
|
||
|
||
return satellites # done with v2
|
||
|
||
# ----------------------------
|
||
# RINEX 3 / 4 parsing
|
||
# ----------------------------
|
||
while current_line:
|
||
# Skip short/noise lines
|
||
if len(current_line) < 23:
|
||
current_line = f.readline()
|
||
line_number += 1
|
||
continue
|
||
|
||
# Parse the epoch line
|
||
parts = current_line.split()
|
||
if len(parts) < 8:
|
||
current_line = f.readline()
|
||
line_number += 1
|
||
continue
|
||
|
||
prn = parts[0].strip()
|
||
system = prn[0]
|
||
|
||
try:
|
||
year = int(parts[1])
|
||
month = int(parts[2])
|
||
day = int(parts[3])
|
||
hour = int(parts[4])
|
||
minute = int(parts[5])
|
||
second = float(parts[6][:2])
|
||
epoch = datetime(
|
||
year,
|
||
month,
|
||
day,
|
||
hour,
|
||
minute,
|
||
int(second),
|
||
int((second % 1) * 1e6),
|
||
)
|
||
lines = [current_line]
|
||
line_count = 4 if system == "R" or system == "S" else 7
|
||
for _ in range(line_count):
|
||
next_line = f.readline()
|
||
line_number += 1
|
||
if not next_line:
|
||
break
|
||
lines.append(next_line)
|
||
|
||
if len(lines) < line_count + 1:
|
||
current_line = f.readline()
|
||
line_number += 1
|
||
continue
|
||
|
||
if system == "R": # GLONASS
|
||
ephemeris = {
|
||
"prn": prn,
|
||
"epoch": epoch,
|
||
"sv_clock_bias": parse_rinex_float(lines[0][23:41]),
|
||
"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]),
|
||
"x_vel": parse_rinex_float(lines[1][23:41]),
|
||
"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][23:41]),
|
||
"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][23:41]),
|
||
"z_acc": parse_rinex_float(lines[3][42:61]),
|
||
"age": parse_rinex_float(lines[3][61:80]),
|
||
"extra": lines[4:],
|
||
}
|
||
elif system == "S": # SBAS (RINEX v4 short form)
|
||
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]
|
||
),
|
||
"x": parse_rinex_float(lines[1][4:23])
|
||
if len(lines) > 1
|
||
else None,
|
||
"x_vel": parse_rinex_float(lines[1][23:42])
|
||
if len(lines) > 1
|
||
else None,
|
||
"x_acc": parse_rinex_float(lines[1][42:61])
|
||
if len(lines) > 1
|
||
else None,
|
||
"health": parse_rinex_float(lines[1][61:80])
|
||
if len(lines) > 1
|
||
else None,
|
||
"y": parse_rinex_float(lines[2][4:23])
|
||
if len(lines) > 2
|
||
else None,
|
||
"y_vel": parse_rinex_float(lines[2][23:42])
|
||
if len(lines) > 2
|
||
else None,
|
||
"y_acc": parse_rinex_float(lines[2][42:61])
|
||
if len(lines) > 2
|
||
else None,
|
||
"z": parse_rinex_float(lines[3][4:23])
|
||
if len(lines) > 3
|
||
else None,
|
||
"z_vel": parse_rinex_float(lines[3][23:42])
|
||
if len(lines) > 3
|
||
else None,
|
||
"z_acc": parse_rinex_float(lines[3][42:61])
|
||
if len(lines) > 3
|
||
else None,
|
||
"extra": lines[4:],
|
||
}
|
||
elif system in ("G", "E", "C", "I", "J"):
|
||
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])
|
||
if len(lines) > 7
|
||
else None,
|
||
"fit_interval": parse_rinex_float(lines[7][23:42])
|
||
if len(lines) > 7
|
||
else None,
|
||
"extra": lines[8:],
|
||
}
|
||
else:
|
||
ephemeris = []
|
||
|
||
if ephemeris:
|
||
satellites.setdefault(prn, []).append(ephemeris)
|
||
|
||
except (ValueError, IndexError):
|
||
# Skip to next line
|
||
pass
|
||
|
||
current_line = f.readline()
|
||
line_number += 1
|
||
|
||
return satellites
|
||
|
||
|
||
def calculate_satellite_position(
|
||
ephemeris: Dict[str, Any], transmit_time: float
|
||
) -> Tuple[float, float, float]:
|
||
"""Calculate satellite position in ECEF coordinates [m], at a given transmission time"""
|
||
system = ephemeris["prn"][0]
|
||
|
||
if system in ("R", "S"): # GLONASS/SBAS
|
||
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
|
||
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
|
||
|
||
# Corrected mean motion
|
||
n0 = sqrt(mu / (a**3))
|
||
n = n0 + ephemeris["delta_n"]
|
||
|
||
# Mean anomaly
|
||
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)
|
||
if abs(ek - ek_old) < 1e-12:
|
||
break
|
||
|
||
# True anomaly
|
||
nu_k = atan2(
|
||
sqrt(1 - ephemeris["ecc"] ** 2) * sin(ek),
|
||
cos(ek) - ephemeris["ecc"],
|
||
)
|
||
|
||
# Argument of latitude
|
||
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
|
||
)
|
||
|
||
# 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
|
||
|
||
# Positions in orbital plane
|
||
xk_prime = rk * cos(uk)
|
||
yk_prime = rk * sin(uk)
|
||
|
||
# Corrected longitude of ascending node
|
||
omega_k = (
|
||
ephemeris["omega0"]
|
||
+ (ephemeris["omega_dot"] - omega_e_dot) * transmit_time
|
||
- omega_e_dot * ephemeris["toe"]
|
||
)
|
||
|
||
# Earth-fixed coordinates
|
||
xk = xk_prime * cos(omega_k) - yk_prime * cos(ik) * sin(omega_k)
|
||
yk = xk_prime * sin(omega_k) + yk_prime * cos(ik) * cos(omega_k)
|
||
zk = yk_prime * sin(ik)
|
||
|
||
return xk, yk, zk
|
||
|
||
|
||
def calculate_satellite_positions(
|
||
ephemeris: Dict[str, Any],
|
||
start_time: datetime,
|
||
end_time: datetime,
|
||
step_min: int = 5,
|
||
) -> List[Tuple[datetime, float, float, float]]:
|
||
"""
|
||
Compute multiple positions over time for a single satellite
|
||
between start_time and end_time.
|
||
|
||
Parameters
|
||
----------
|
||
ephemeris : Dict[str, Any]
|
||
Satellite ephemeris data containing orbital parameters
|
||
start_time : datetime
|
||
Start time for position calculations
|
||
end_time : datetime
|
||
End time for position calculations
|
||
step_min : int, optional
|
||
Time step in minutes between calculations, by default 5
|
||
|
||
Returns
|
||
-------
|
||
List[Tuple[datetime, float, float, float]]
|
||
List of tuples containing (timestamp, x, y, z) coordinates
|
||
in ECEF frame for each time step
|
||
"""
|
||
positions = []
|
||
current_time = start_time
|
||
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()
|
||
|
||
if abs(transmit_time) <= max_valid_time:
|
||
x, y, z = calculate_satellite_position(ephemeris, transmit_time)
|
||
positions.append((current_time, x, y, z))
|
||
|
||
current_time += timedelta(minutes=step_min)
|
||
|
||
return positions
|
||
|
||
|
||
def ecef_to_az_el(
|
||
x: float,
|
||
y: float,
|
||
z: float,
|
||
obs_lat: float,
|
||
obs_lon: float,
|
||
obs_alt: float,
|
||
) -> Tuple[float, float]:
|
||
"""
|
||
Convert ECEF coordinates to azimuth and elevation angles.
|
||
|
||
Parameters
|
||
----------
|
||
x : float
|
||
Satellite X coordinate in ECEF frame (meters)
|
||
y : float
|
||
Satellite Y coordinate in ECEF frame (meters)
|
||
z : float
|
||
Satellite Z coordinate in ECEF frame (meters)
|
||
obs_lat : float
|
||
Observer latitude in radians
|
||
obs_lon : float
|
||
Observer longitude in radians
|
||
obs_alt : float
|
||
Observer altitude in meters above WGS-84 ellipsoid
|
||
|
||
Returns
|
||
-------
|
||
Tuple[float, float]
|
||
Azimuth and elevation angles in degrees.
|
||
Azimuth: 0° to 360° (0° = North, 90° = East)
|
||
Elevation: 0° to 90° (0° = horizon, 90° = zenith)
|
||
"""
|
||
# WGS-84 parameters
|
||
a = 6378137.0 # semi-major axis
|
||
e_sq = 6.69437999014e-3 # first eccentricity squared
|
||
|
||
# Convert geodetic coordinates to ECEF
|
||
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)
|
||
|
||
# Vector from observer to satellite
|
||
dx = x - obs_x
|
||
dy = y - obs_y
|
||
dz = z - obs_z
|
||
|
||
# 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
|
||
)
|
||
|
||
# Calculate azimuth and elevation
|
||
azimuth = atan2(enu_x, enu_y)
|
||
elevation = atan2(enu_z, sqrt(enu_x**2 + enu_y**2))
|
||
|
||
# Convert to degrees and adjust azimuth to 0-360
|
||
azimuth = np.degrees(azimuth) % 360
|
||
elevation = np.degrees(elevation)
|
||
|
||
return azimuth, elevation
|
||
|
||
|
||
def plot_satellite_tracks(
|
||
satellites: Dict[str, List[Dict[str, Any]]],
|
||
obs_lat: float,
|
||
obs_lon: float,
|
||
obs_alt: float,
|
||
footer_text: Optional[str] = None,
|
||
filename: Optional[str] = None,
|
||
show_plot: bool = True,
|
||
start_time: Optional[datetime] = None,
|
||
end_time: Optional[datetime] = None,
|
||
elev_mask: float = 5.0,
|
||
output_format: str = "pdf",
|
||
) -> None:
|
||
"""
|
||
Plot trajectories for all visible satellites in a polar skyplot.
|
||
|
||
Parameters
|
||
----------
|
||
satellites : Dict[str, List[Dict[str, Any]]]
|
||
Dictionary mapping satellite PRN strings to lists of ephemeris data
|
||
obs_lat : float
|
||
Observer latitude in radians
|
||
obs_lon : float
|
||
Observer longitude in radians
|
||
obs_alt : float
|
||
Observer altitude in meters
|
||
footer_text : Optional[str], optional
|
||
Text to display at bottom of plot, by default None
|
||
filename : Optional[str], optional
|
||
Input filename for naming output, by default None
|
||
show_plot : bool, optional
|
||
Whether to display the plot interactively, by default True
|
||
start_time : Optional[datetime], optional
|
||
Start time for position calculations, by default None (auto-detect)
|
||
end_time : Optional[datetime], optional
|
||
End time for position calculations, by default None (auto-detect)
|
||
elev_mask : float, optional
|
||
Minimum elevation angle in degrees to plot, by default 5.0
|
||
output_format : str, optional
|
||
Output file format, by default "pdf"
|
||
|
||
Returns
|
||
-------
|
||
None
|
||
Saves plot to file and optionally displays it
|
||
"""
|
||
plt.rcParams["pdf.fonttype"] = 42 # TrueType fonts
|
||
plt.rcParams["ps.fonttype"] = 42 # TrueType fonts
|
||
plt.rcParams["font.family"] = "serif"
|
||
plt.rcParams["font.serif"] = ["Times New Roman", "Times", "DejaVu Serif"]
|
||
plt.rcParams["mathtext.fontset"] = "dejavuserif" # For math text
|
||
plt.rcParams["savefig.dpi"] = 300 # for jpg and png
|
||
plt.rcParams["savefig.bbox"] = "tight" # Always use bbox_inches='tight'
|
||
plt.rcParams["svg.fonttype"] = "none" # Make SVG text editable
|
||
fig = plt.figure(figsize=(8, 8))
|
||
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_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)
|
||
|
||
# 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": "lightgray", # SBAS
|
||
"L": "cyan", # LEO (new in RINEX v4)
|
||
}
|
||
|
||
# System names mapping
|
||
system_names = {
|
||
"G": "GPS",
|
||
"E": "Galileo",
|
||
"R": "GLONASS",
|
||
"C": "BeiDou",
|
||
"J": "QZSS",
|
||
"I": "IRNSS",
|
||
"S": "SBAS",
|
||
"L": "LEO",
|
||
}
|
||
|
||
# Find which systems are actually present
|
||
present_systems = {
|
||
prn[0] for prn in satellites.keys() if prn[0] in system_colors
|
||
}
|
||
|
||
# Plot each satellite
|
||
for prn, ephemeris_list in satellites.items():
|
||
# Default to purple for unknown systems
|
||
color = system_colors.get(prn[0], "purple")
|
||
|
||
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]
|
||
if prev_eph:
|
||
ephemeris = max(prev_eph, key=lambda e: e["epoch"])
|
||
else:
|
||
ephemeris = min(
|
||
ephemeris_list,
|
||
key=lambda e: abs((e["epoch"] - mid_time).total_seconds()),
|
||
)
|
||
|
||
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
|
||
}
|
||
)
|
||
start_time = min(all_epochs)
|
||
end_time = max(all_epochs)
|
||
|
||
positions = calculate_satellite_positions(
|
||
ephemeris, start_time, end_time
|
||
)
|
||
|
||
# Split into visible segments
|
||
segments = []
|
||
current_seg_az = []
|
||
current_seg_el = []
|
||
for _, x, y, z in positions:
|
||
azimuth, elevation = ecef_to_az_el(
|
||
x, y, z, obs_lat, obs_lon, obs_alt
|
||
)
|
||
if elevation > elev_mask:
|
||
current_seg_az.append(azimuth)
|
||
current_seg_el.append(elevation)
|
||
else:
|
||
if len(current_seg_az) > 1:
|
||
segments.append((current_seg_az, current_seg_el))
|
||
current_seg_az, current_seg_el = [], []
|
||
if len(current_seg_az) > 1:
|
||
segments.append((current_seg_az, current_seg_el))
|
||
|
||
# Plot each segment separately
|
||
for az_seg, el_seg in segments:
|
||
theta = np.radians(az_seg)
|
||
r = 90 - np.array(el_seg)
|
||
ax.plot(
|
||
theta, r, "-", color=color, alpha=0.7, linewidth=2.5, zorder=1
|
||
)
|
||
|
||
# Arrow at end
|
||
if len(theta) >= 2:
|
||
dx = theta[-1] - theta[-2]
|
||
dy = r[-1] - r[-2]
|
||
arrow_length_factor = 1.8
|
||
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,
|
||
},
|
||
zorder=2,
|
||
)
|
||
|
||
# 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": system_colors.get(prn[0], "white"),
|
||
"alpha": 0.2,
|
||
"pad": 2,
|
||
},
|
||
zorder=3,
|
||
)
|
||
|
||
# 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}.{output_format}"
|
||
else:
|
||
output_name = f"skyplot.{output_format}"
|
||
|
||
plt.savefig(output_name, format=output_format)
|
||
print(f"Image saved as {output_name}")
|
||
if show_plot:
|
||
try:
|
||
plt.show()
|
||
except KeyboardInterrupt:
|
||
print("\nExecution interrupted by the user. Exiting.")
|
||
plt.close()
|
||
else:
|
||
plt.close()
|
||
|
||
|
||
def main():
|
||
"""Generate the skyplot"""
|
||
try:
|
||
# Set system names and codes
|
||
system_name_to_code = {
|
||
"GPS": "G",
|
||
"GLONASS": "R",
|
||
"GALILEO": "E",
|
||
"BEIDOU": "C",
|
||
"QZSS": "J",
|
||
"IRNSS": "I",
|
||
"SBAS": "S",
|
||
"LEO": "L",
|
||
}
|
||
|
||
# Set up argument parser
|
||
parser = argparse.ArgumentParser(
|
||
description="Generate a GNSS skyplot from a RINEX navigation file",
|
||
epilog="Example: skyplot.py brdc0010.22n -33.4592 -70.6453 520.0 --format png --system G E --elev-mask 10 --no-show",
|
||
)
|
||
|
||
# Positional arguments
|
||
parser.add_argument("filename", help="RINEX navigation file path")
|
||
|
||
parser.add_argument(
|
||
"lat",
|
||
nargs="?",
|
||
type=float,
|
||
default=DEFAULT_LAT,
|
||
help=f"Observer latitude in degrees (default: {DEFAULT_LAT}° N)",
|
||
)
|
||
|
||
parser.add_argument(
|
||
"lon",
|
||
nargs="?",
|
||
type=float,
|
||
default=DEFAULT_LON,
|
||
help=f"Observer longitude in degrees (default: {DEFAULT_LON}° E)",
|
||
)
|
||
|
||
parser.add_argument(
|
||
"alt",
|
||
nargs="?",
|
||
type=float,
|
||
default=DEFAULT_ALT,
|
||
help=f"Observer altitude in meters (default: {DEFAULT_ALT} m)",
|
||
)
|
||
|
||
# Optional arguments
|
||
parser.add_argument(
|
||
"--elev-mask",
|
||
type=float,
|
||
default=5.0,
|
||
help="Elevation mask in degrees for plotting satellite tracks (default: 5°)",
|
||
)
|
||
|
||
parser.add_argument(
|
||
"--format",
|
||
type=str,
|
||
default="pdf",
|
||
choices=["pdf", "eps", "jpg", "png", "svg"],
|
||
help="Output file format for plot (default: pdf)",
|
||
)
|
||
|
||
parser.add_argument(
|
||
"--no-show",
|
||
action="store_true",
|
||
help="Run without displaying plot window",
|
||
)
|
||
|
||
parser.add_argument(
|
||
"--system",
|
||
nargs="+",
|
||
help="Only plot satellites from these systems (e.g., G R E or GPS GLONASS Galileo)",
|
||
)
|
||
|
||
parser.add_argument(
|
||
"--use-obs",
|
||
action="store_true",
|
||
help="Use corresponding RINEX observation file to bound the skyplot to the receiver time window",
|
||
)
|
||
|
||
parser.add_argument(
|
||
"-v",
|
||
"--version",
|
||
action="version",
|
||
version=f"%(prog)s {__version__}",
|
||
help="Show program version and exit",
|
||
)
|
||
|
||
# Parse all arguments with full validation
|
||
args = parser.parse_args()
|
||
|
||
filename = args.filename
|
||
user_provided_position = (
|
||
(args.lat != DEFAULT_LAT)
|
||
or (args.lon != DEFAULT_LON)
|
||
or (args.alt != DEFAULT_ALT)
|
||
)
|
||
|
||
# Convert coordinates to radians
|
||
obs_lat = np.radians(args.lat)
|
||
obs_lon = np.radians(args.lon)
|
||
obs_alt = args.alt
|
||
|
||
# Read RINEX file
|
||
print(f"Reading {filename} ...")
|
||
try:
|
||
satellites = read_rinex_nav(filename)
|
||
except FileNotFoundError:
|
||
print(f"Error: File {filename} not found.")
|
||
return 1
|
||
|
||
if not satellites:
|
||
print("No satellite data found in the file.")
|
||
return 1
|
||
|
||
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 1
|
||
|
||
# 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",
|
||
"J": "QZSS",
|
||
"I": "IRNSS",
|
||
"S": "SBAS",
|
||
"L": "LEO",
|
||
}.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:
|
||
obs_path = find_obs_for_nav(filename)
|
||
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 in {obs_path}: from {use_start} to {use_end}"
|
||
)
|
||
else:
|
||
print(
|
||
f"\nWarning: Could not read valid times from {obs_path}. Using NAV span instead."
|
||
)
|
||
if not user_provided_position:
|
||
approx_pos = get_approx_position_from_obs(obs_path)
|
||
if approx_pos is not None:
|
||
lat, lon, h = approx_pos
|
||
obs_lat = np.radians(lat)
|
||
obs_lon = np.radians(lon)
|
||
obs_alt = h
|
||
print(
|
||
f"\nObserver position found in {obs_path}: lat {lat:.2f}°, lon {lon:.2f}°, height {h:.2f} m."
|
||
)
|
||
|
||
# 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,
|
||
output_format=args.format,
|
||
)
|
||
except Exception as e:
|
||
print(f"Error: {str(e)}")
|
||
return 1
|
||
|
||
return 0
|
||
|
||
|
||
if __name__ == "__main__":
|
||
main()
|