skyplot: add reading of RINEX v2 navigation files

Recover Python 3.6 compatibility (use old-style type hints for improved compatibility)

utils/skyplot/skyplot.py

@@ -31,6 +31,7 @@ import sys
 from datetime import datetime, timedelta
 from math import atan2, cos, sin, sqrt
 from pathlib import Path
+from typing import Tuple, Optional
 
 try:
     import matplotlib.pyplot as plt
@@ -42,7 +43,7 @@ except ImportError:
 
 __version__ = "1.0.0"
 
-def read_obs_time_bounds(obs_path: str) -> tuple[datetime | None, datetime | None]:
+def read_obs_time_bounds(obs_path: str) -> Tuple[Optional[datetime], Optional[datetime]]:
     """
     Return (start_time, end_time) from a RINEX observation file (v2/3/4)
     by scanning epoch lines. If parsing fails or the file is not OBS, return (None, None).
@@ -106,7 +107,7 @@ def read_obs_time_bounds(obs_path: str) -> tuple[datetime | None, datetime | Non
         return (None, None)
 
 
-def find_obs_for_nav(nav_file: str) -> str | None:
+def find_obs_for_nav(nav_file: str) -> Optional[str]:
     """Find corresponding RINEX OBS file for a given NAV file (v2/v3/v4), covering all standard extensions."""
     nav_path = Path(nav_file)
     tried = []
@@ -114,7 +115,7 @@ def find_obs_for_nav(nav_file: str) -> str | None:
     stem = nav_path.stem
     suffix = nav_path.suffix
 
-    # --- RINEX v2: replace last letter of extension with 'O' or 'o'
+    # --- RINEX v2 names: replace last letter of extension with 'O' or 'o'
     if suffix and suffix[-1].isalpha():
         for o_type in ('O', 'o'):
             candidate = nav_path.with_suffix(suffix[:-1] + o_type)
@@ -122,7 +123,7 @@ def find_obs_for_nav(nav_file: str) -> str | None:
             if candidate.exists():
                 return str(candidate)
 
-    # --- RINEX v3/v4: handle standard extensions and common modifiers
+    # --- RINEX v3/v4 names: handle standard extensions and common modifiers
     gnss_patterns = [
         # Mixed constellations
         ("_MN", "_MO"), ("_mn", "_mo"),
@@ -213,52 +214,232 @@ def parse_rinex_float(s: str) -> float:
         return 0.0  # Default if parsing fails
 
 
+def read_rinex_header(filename: str) -> Tuple[str, str]:
+    """Return (version_str, file_type_char) from the 'RINEX VERSION / TYPE' header line."""
+    with open(filename, 'r', encoding='utf-8', errors='ignore') as f:
+        for line in f:
+            if "RINEX VERSION / TYPE" in line:
+                version = line[0:9].strip()  # F9.2 in v2/v3/v4
+                ftype = line[20:21].upper()  # 'N' (GPS nav v2), 'G' (GLO nav v2), 'H' (GEO/SBAS v2), 'N' in v3/4 too
+                return version, ftype
+            if "END OF HEADER" in line:
+                break
+    return "", ""
+
+
 def read_rinex_nav(filename):
-    """Read RINEX v3/4 navigation file into a dictionary of satellites."""
+    """
+    Read RINEX v2/v3/v4 navigation file into a dict { 'Gxx': [eph...], 'Rxx': [...], 'Sxxx': [...] }.
+    """
+    version_str, ftype = read_rinex_header(filename)
+    is_v2 = version_str.startswith('2')
+
     satellites = {}
     line_number = 0
-    with open(filename, 'r', encoding='utf-8') as f:
+    with open(filename, 'r', encoding='utf-8', errors='ignore') as f:
         # Skip header
         while True:
             line = f.readline()
             line_number += 1
             if not line:
-                return satellites  # Empty file
+                return satellites
             if "END OF HEADER" in line:
                 break
 
-        # Read ephemeris data
         current_line = f.readline()
         line_number += 1
+
+        # ----------------------------
+        # RINEX 2.10 / 2.11 parsing
+        # ----------------------------
+        if is_v2:
+            # File type: 'N' (GPS), 'G' (GLONASS), 'H' (GEO/SBAS)
+            v2_system = ftype  # keep original char
+            while current_line:
+                # Skip empties
+                if not current_line.strip():
+                    current_line = f.readline()
+                    line_number += 1
+                    continue
+
+                try:
+                    # --- First record line: PRN/EPOCH/CLOCK --------------------
+                    # Formats per RINEX 2.11 Table A4 (GPS) and Table A11 (GLONASS).
+                    # PRN I2 in cols 1-2. Then yy, mm, dd, hh, mi (I2 with 1X between), ss F5.1,
+                    # then 3D19.12 (clock bias, drift, drift rate).
+                    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) as e:
+                    # 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
 
-            prn = current_line[:3].strip()
+            # Parse the epoch line
-            if not prn:
+            parts = current_line.split()
+            if len(parts) < 8:
                 current_line = f.readline()
                 line_number += 1
                 continue
 
-            system = prn[0]  # G, R, E, etc.
+            prn = parts[0].strip()
+            system = prn[0]
 
             try:
-                # Parse epoch fields
+                year = int(parts[1])
-                year = int(current_line[4:8])
+                month = int(parts[2])
-                month = int(current_line[9:11])
+                day = int(parts[3])
-                day = int(current_line[12:14])
+                hour = int(parts[4])
-                hour = int(current_line[15:17])
+                minute = int(parts[5])
-                minute = int(current_line[18:20])
+                second = float(parts[6])
-                second = int(float(current_line[21:23]))
+                epoch = datetime(year, month, day, hour, minute, int(second), int((second % 1) * 1e6))
 
-                year += 2000 if year < 80 else 0
-                epoch = datetime(year, month, day, hour, minute, second)
-
-                # Read the next lines
                 lines = [current_line]
-                line_count = 4 if system == 'R' else 7
+                line_count = 4 if system == 'R' or system == 'S' else 7
                 for _ in range(line_count):
                     next_line = f.readline()
                     line_number += 1
@@ -271,36 +452,34 @@ def read_rinex_nav(filename):
                     line_number += 1
                     continue
 
-                # Build ephemeris dictionary
                 if system == 'R':  # GLONASS
                     ephemeris = {
                         'prn': prn,
                         'epoch': epoch,
-                        'sv_clock_bias': parse_rinex_float(lines[0][23:42]),
+                        '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]),  # Position (km)
+                        'x': parse_rinex_float(lines[1][4:23]),
-                        'x_vel': parse_rinex_float(lines[1][23:42]),  # Velocity (km/s)
+                        '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][23:42]),
+                        '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][23:42]),
+                        '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:]  # Keep any extra RINEX v4 lines
+                        'extra': lines[4:]
                     }
-                elif system == 'S':  # SBAS (RINEX v4)
+                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]),
-                        # SBAS messages are shorter: 4 lines instead of 8
                         '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,
@@ -311,9 +490,9 @@ def read_rinex_nav(filename):
                         '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:]  # capture anything beyond
+                        'extra': lines[4:]
                     }
-                else:  # GPS, Galileo, BeiDou, QZSS, IRNSS, etc.
+                else:
                     ephemeris = {
                         'prn': prn,
                         'epoch': epoch,
@@ -346,25 +525,14 @@ def read_rinex_nav(filename):
                         '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:]  # Keep any extra RINEX v4 lines
+                        'extra': lines[8:]
                     }
 
-                if prn not in satellites:
+                satellites.setdefault(prn, []).append(ephemeris)
-                    satellites[prn] = []
-                satellites[prn].append(ephemeris)
 
-            except (ValueError, IndexError) as e:
+            except (ValueError, IndexError):
-                print(f"\nError in file {filename} at line {line_number}:")
+                # Skip to next line
-                print(f"  PRN: {prn}")
+                pass
-                print(f"  Line content: {current_line.strip()}")
-                print(f"  Error type: {type(e).__name__}")
-                print(f"  Error details: {str(e)}")
-                print("Skipping to next satellite block ...\n")
-                # Skip to next block by reading until next PRN
-                while current_line and not current_line.startswith(prn[0]):
-                    current_line = f.readline()
-                    line_number += 1
-                continue
 
             current_line = f.readline()
             line_number += 1
@@ -758,7 +926,7 @@ def main():
         try:
             satellites = read_rinex_nav(filename)
         except FileNotFoundError:
-            print(f"Error: File '{filename}' not found.")
+            print(f"Error: File {filename} not found.")
             return 1
 
         if not satellites: