GTimes - High-Precision GPS Time Processing Library

GTimes is a high-precision GPS time conversion and processing library designed for GNSS applications, geodetic research, and scientific computing. It provides microsecond-accurate conversions between GPS time and UTC, handles leap seconds correctly, and offers comprehensive tools for time-related calculations in GPS data processing workflows.

🚀 Key Features

• High-Precision GPS Time Conversions: Microsecond-accurate GPS ↔ UTC conversions
• Leap Second Management: Automatic handling of leap seconds with up-to-date leap second data
• RINEX Processing Support: Time formatting and file organization for RINEX workflows
• GAMIT/GLOBK Integration: Fractional year conversions for GAMIT time series analysis
• Command-Line Interface: Powerful timecalc tool for shell scripting and automation
• Scientific Validation: Comprehensive testing against known GPS time standards
• Cross-Platform: Works on Linux, Windows, and macOS with Python 3.8+

📦 Installation

From PyPI (Recommended)

pip install gtimes

Development Installation

git clone https://github.com/bennigo/gtimes.git
cd gtimes
pip install -e .[dev]

With Documentation

pip install gtimes[docs]
mkdocs serve  # View documentation locally

🏃 Quick Start

Basic GPS Time Conversions

from gtimes.gpstime import gpsFromUTC, UTCFromGps
import datetime

# Convert current time to GPS
now = datetime.datetime.utcnow()
gps_week, sow, gps_day, sod = gpsFromUTC(
    now.year, now.month, now.day,
    now.hour, now.minute, now.second
)

print(f"Current GPS time: Week {gps_week}, SOW {sow:.3f}")

# Convert GPS time back to UTC
utc_datetime = UTCFromGps(gps_week, sow, dtimeObj=True)
print(f"Back to UTC: {utc_datetime}")

GAMIT Fractional Year Processing

from gtimes.timefunc import TimefromYearf, dTimetoYearf
import datetime

# Convert GAMIT fractional year to datetime
gamit_time = 2024.0411  # ~Feb 15, 2024
dt = TimefromYearf(gamit_time)
print(f"GAMIT {gamit_time:.4f} = {dt.strftime('%Y-%m-%d %H:%M:%S')}")

# Convert datetime to fractional year
date = datetime.datetime(2024, 6, 15, 12, 0, 0)
yearf = dTimetoYearf(date)
print(f"{date} = {yearf:.6f}")

Command-Line Usage

# Get GPS week and day for today
timecalc -wd

# GPS time for specific date
timecalc -wd -d "2024-01-15"

# Generate RINEX filenames
timecalc -l "REYK%j0.%yO" "7D" -d "2024-01-15"

# Get fractional year for GAMIT
timecalc -yf -d "2024-06-15"

📊 Real-World Applications

GPS Network Processing

from gtimes.gpstime import gpsFromUTC
from gtimes.timefunc import datepathlist
import datetime

# Process GPS station data
stations = ['REYK', 'HOFN', 'AKUR', 'VMEY']
start_date = datetime.datetime(2024, 1, 15)

for station in stations:
    # Generate RINEX observation files
    obs_files = datepathlist(f"{station}%j0.%yO", "7D", start_date, 
                            start_date + datetime.timedelta(days=7))
    
    print(f"{station} files: {len(obs_files)} files")
    for obs_file in obs_files[:3]:  # Show first 3
        print(f"  {obs_file}")

RINEX File Organization

from gtimes.timefunc import datepathlist
import datetime

# Create processing directory structure
start = datetime.datetime(2024, 1, 1)
end = datetime.datetime(2024, 2, 1)

# Daily processing directories
daily_dirs = datepathlist("/gps_proc/%Y/%j/", "1D", start, end)
print("Daily processing directories:")
for directory in daily_dirs[:5]:
    print(f"  {directory}")

# Weekly GPS processing
weekly_dirs = datepathlist("/gps_proc/week_%U/", "7D", start, end)
print("Weekly processing directories:")
for directory in weekly_dirs:
    print(f"  {directory}")

🛠️ Advanced Usage

High-Precision Time Series

from gtimes.gpstime import gpsFromUTC, UTCFromGps
import datetime

# Process time series with microsecond precision
timestamps = [
    datetime.datetime(2024, 1, 15, 12, 30, 45, 123456),
    datetime.datetime(2024, 1, 15, 12, 30, 46, 234567),
    datetime.datetime(2024, 1, 15, 12, 30, 47, 345678),
]

gps_times = []
for ts in timestamps:
    # Convert with microsecond precision
    week, sow, day, sod = gpsFromUTC(
        ts.year, ts.month, ts.day, ts.hour, ts.minute,
        ts.second + ts.microsecond / 1e6
    )
    gps_times.append((week, sow))
    
    # Verify round-trip accuracy
    utc_back = UTCFromGps(week, sow, dtimeObj=True)
    diff = abs((utc_back - ts).total_seconds())
    print(f"GPS: Week {week}, SOW {sow:.6f}, Round-trip error: {diff:.6f}s")

Leap Second Analysis

from gtimes.gpstime import getleapSecs, leapSecDict
import datetime

# Analyze leap second history
leap_dict = leapSecDict()
print(f"Total leap seconds in database: {len(leap_dict)}")

# Check leap seconds for different epochs
important_dates = [
    ("GPS Epoch", datetime.datetime(1980, 1, 6)),
    ("Y2K", datetime.datetime(2000, 1, 1)),
    ("Recent", datetime.datetime(2024, 1, 1)),
]

for label, date in important_dates:
    gps_leap = getleapSecs(date, gpst=True)
    utc_leap = getleapSecs(date, gpst=False)
    print(f"{label}: GPS={gps_leap}, UTC={utc_leap} leap seconds")

🔧 Development

Setting Up Development Environment

# Clone repository
git clone https://github.com/bennigo/gtimes.git
cd gtimes

# Install development dependencies
pip install -e .[dev,test,docs,quality]

# Run tests
pytest tests/ -v

# Run quality checks
ruff check src/ tests/
mypy src/gtimes/

# Build documentation
mkdocs build
mkdocs serve

Running Benchmarks

# Performance benchmarks
pytest tests/benchmark/ --benchmark-only

# Scientific validation
python tests/validate_leap_seconds.py

# Documentation link checking
python tests/check_docs_links.py

📚 Documentation

• Full Documentation: Complete API reference and tutorials
• Installation Guide: Detailed installation instructions
• Quick Start Tutorial: Get started quickly
• API Reference: Complete function documentation
• Examples: Real-world usage examples
• Contributing Guide: How to contribute

🧪 Testing & Quality

GTimes maintains high standards for accuracy and reliability:

• ✅ Comprehensive Test Suite: 200+ tests covering all functionality
• ✅ Scientific Validation: GPS time accuracy verified against known standards
• ✅ Multi-Platform Testing: Linux, Windows, macOS compatibility
• ✅ Performance Benchmarks: >1000 GPS conversions/second
• ✅ Code Quality: 90%+ test coverage, strict linting, type checking
• ✅ Documentation: Complete API documentation with examples

Accuracy Guarantees

• Microsecond Precision: GPS ↔ UTC conversions accurate to microseconds
• Leap Second Handling: Up-to-date leap second data (18 leap seconds as of 2024)
• GPS Epoch Compliance: Correct handling of GPS epoch (January 6, 1980)
• Round-Trip Accuracy: UTC → GPS → UTC conversions within 1μs

🌍 Applications

GTimes is used in various scientific and engineering applications:

• GNSS Data Processing: RINEX file processing and GPS network analysis
• Geodetic Research: Coordinate time series and plate motion studies
• Seismology: GPS station monitoring and earthquake research
• Meteorology: GPS meteorology and atmospheric studies
• Surveying: High-precision positioning and coordinate systems
• Satellite Navigation: GPS receiver testing and algorithm development

🏢 Institutional Use

GTimes is developed and maintained by researchers at:

• Veðurstofan Íslands (Icelandic Met Office): Operational GPS network monitoring
• GPS Research Community: GAMIT/GLOBK processing workflows
• Scientific Institutions: Geodetic research and GNSS applications

🤝 Contributing

We welcome contributions! Please see our Contributing Guide for details.

Quick Contribution Steps

# Fork the repository on GitHub
git clone https://github.com/your-username/gtimes.git
cd gtimes

# Install development environment
pip install -e .[dev,test]

# Make changes and test
pytest tests/ -v
ruff check src/ tests/

# Submit pull request

📄 License

GTimes is released under the MIT License. See LICENSE file for details.

🙏 Acknowledgments

• IGS Community: For GPS time standards and RINEX specifications
• GAMIT/GLOBK Team: For fractional year time representations
• Scientific Python Community: For the excellent ecosystem
• Veðurstofan Íslands: For supporting open-source GPS research tools

📞 Support & Contact

• 📖 Documentation: https://bennigo.github.io/gtimes
• 🐛 Bug Reports: GitHub Issues
• 💬 Discussions: GitHub Discussions
• 📧 Email: bgo@vedur.is

GTimes - Precision GPS time processing for scientific applications 🛰️⏰🔬