LoRa Line of Sight Calculator

A web-based tool for analyzing LoRa radio coverage between multiple points, accounting for terrain elevation and calculating link budgets with Fresnel zone clearance.

Features

• 🗺️ Interactive Map Interface - Click to add multiple waypoints
• 📡 LoRa Link Budget Calculator - Customizable radio parameters
• 🏔️ Terrain Analysis - Real elevation data with earth curvature compensation
• 📊 Fresnel Zone Calculation - RF propagation modeling
• 🎨 Modern Dark UI - Clean, professional interface
• ✅ Multi-Point Analysis - Test coverage between 2+ locations
• 🌈 Visual Feedback - Color-coded links (Green = Good, Orange = Marginal, Red = Blocked)

LoRa Parameters

Customize all key LoRa radio settings:

• Frequency: 433 MHz or 868 MHz
• Bandwidth: 125, 250, or 500 kHz
• Spreading Factor: SF7 to SF12
• Coding Rate: 4/5, 4/6, 4/7, 4/8
• TX Power: 2 to 27 dBm
• Antenna Gains: -2 to 15 dBi (TX and RX)

Calculated Results

• Link Budget (dB)
• Data Rate (bps/kbps)
• Receiver Sensitivity (dBm)
• Maximum Range (km)
• Received Power (dBm)
• Link Margin (dB)
• Fresnel Zone Clearance (%)

How to Use

1. Add Points: Click "Add Point" button, then click on the map
2. Configure Radio: Adjust LoRa parameters in the right panel
3. Analyze: Click "Analyze LoS" to calculate link quality
4. Review Results: Check elevation profile and link analysis

Color Coding

• 🟢 Green: Excellent/Good link quality with clear LoS
• 🟡 Orange: Marginal link quality or limited Fresnel clearance
• 🔴 Red: Poor link quality or blocked line of sight

Technical Details

Link Budget Calculation

Received Power = TX Power + TX Gain + RX Gain - Path Loss - Misc Losses
Link Margin = Received Power - Receiver Sensitivity
Link Budget = Link Margin - Fade Margin

Free Space Path Loss (FSPL)

FSPL (dB) = 20·log₁₀(d) + 20·log₁₀(f) + 32.45
where:
  d = distance (km)
  f = frequency (MHz)

Fresnel Zone

The tool calculates the first Fresnel zone and requires 60% clearance for reliable LoRa communication:

r = 17.3 × √(d₁ × d₂ / (f × D))
where:
  r = Fresnel radius (m)
  d₁, d₂ = distances from point (km)
  f = frequency (MHz)
  D = total distance (km)

Data Rate Calculation

DR = SF × (BW / 2^SF) × (4 / CR)
where:
  SF = Spreading Factor (7-12)
  BW = Bandwidth (Hz)
  CR = Coding Rate denominator (5-8)

Data Sources

• Elevation Data: Open-Elevation API (SRTM 30m resolution)
• Map Tiles: CARTO Dark Matter
• Mapping: Leaflet.js
• Charts: Chart.js

Installation

GitHub Pages Deployment

1. Fork or clone this repository
2. Enable GitHub Pages in repository settings
3. Set source to main branch
4. Access at https://yourusername.github.io/lora-los-tool/

Local Development

# Clone the repository
git clone https://github.com/yourusername/lora-los-tool.git
cd lora-los-tool

# Serve with any HTTP server
python -m http.server 8000
# or
npx http-server

# Open browser to http://localhost:8000

No build process required - pure HTML/CSS/JavaScript!

File Structure

lora-los-tool/
├── index.html              # Main HTML file
├── styles.css              # Dark theme styling
├── app.js                  # Main application logic
├── lora-calculator.js      # LoRa link budget calculations
├── elevation-service.js    # Terrain elevation API
└── README.md              # This file

Browser Compatibility

• ✅ Chrome/Edge (recommended)
• ✅ Firefox
• ✅ Safari
• ⚠️ Requires modern browser with ES6+ support

API Rate Limits

The Open-Elevation API is used for terrain data. For heavy usage, consider:

• Implementing caching (already included)
• Using alternative elevation APIs (Mapbox, Google Elevation)
• Self-hosting elevation data

Future Enhancements

• OSM Buildings integration for urban obstruction modeling
• Multiple receiver points with coverage heatmap
• Export results to PDF/image
• Save/load configurations
• Mobile antenna pattern support
• Weather/atmospheric loss modeling
• Real-time GPS integration

Contributing

Contributions welcome! Please feel free to submit a Pull Request.

License

MIT License - feel free to use this tool for any purpose.

Acknowledgments

• LoRa sensitivity values based on Semtech datasheets
• RF propagation models follow ITU-R recommendations
• Built for the mesh networking and LoRa community

Related Projects

• Reticulum Network Stack
• NomadNet
• RNode Firmware

Author

Created for the LoRa/Reticulum community

Support

If you find this tool useful, please give it a ⭐ on GitHub!

For issues or feature requests, please use the GitHub Issues page.