Frequently Asked Questions

General

What is Aegis-Beacon?

Aegis-Beacon is an open-source, ultra-low-cost emergency rescue beacon designed for avalanche survival, backcountry emergencies, and SAR operations. It transmits Morse code with GPS coordinates on 433 MHz.

How much does it cost?

Total BOM cost is ~$23-28 USD using AliExpress/LCSC components. See Hardware Components for complete parts list.

How long does the battery last?

In BEACON mode with 10-second sleep interval: ~65 hours on a single 18650 cell. See Power Management for detailed runtime estimates.

Is it legal to use?

Check local regulations. In the EU, PMR446 allows 500mW without license. In the US, FRS allows 2W without license. See Frequency Compatibility for regional details.

Hardware

What receiver do I need?

Any AM-mode receiver on 433 MHz:

• Baofeng with AM mode
• Handheld scanner
• Ham radio transceiver
• RTL-SDR + SDR# software

The SX1262 CW carrier is detected identically to OOK.

Can I run this without GPS?

Yes. Set gpsEnabled = false in the CONFIG portal. The beacon works without GPS — it just transmits SOS or SOS DE [NAME] as configured.

Does it work through snow?

433 MHz penetrates wet snow at ~3 dB/m attenuation. The E22-400M30S at +30 dBm PA compensates significantly. At 1m burial depth expect ~3-9 dB signal loss — well within the link budget.

What battery should I use?

Any 18650 Li-ion cell works. For alpine deployments, use LiFePO4 (rated to -30C) for better cold weather performance.

Firmware

How do I update firmware?

1. Connect ESP32 via USB
2. Open Arduino IDE or PlatformIO
3. Upload new firmware
4. Settings are preserved in NVS

Can I change settings without reflashing?

Yes. Use the CONFIG portal (WiFi AP) to change all settings at runtime. Hold SEL for 3 seconds to start WiFi AP.

What is the maximum range?

Line of sight: 15+ km. Mountain terrain: 5-10 km. Urban: 1-3 km. See RF Design for link budget analysis.

How accurate are GPS coordinates?

The transmitted DDM format encodes ~0.1 minute precision (~185m). Full decimal coordinates are logged to Serial at much higher precision. For search purposes, ~200m accuracy is sufficient.

Assembly

Do I need SMD soldering skills?

Yes. The project uses 0805 SMD components. If you’re new to soldering, practice on scrap boards first.

How long does assembly take?

Approximately 3-4 hours for experienced builders. First-time builders may need 5-6 hours.

Can I 3D print the enclosure?

Yes. STL files are available in the repository. Use PLA or PETG for durability.

What tools do I need?

• Soldering iron (25-40W, fine tip)
• Solder (60/40 or lead-free)
• Flux
• Multimeter
• Wire strippers

Operation

How do I switch modes?

Press MODE button to toggle between BEACON and SEARCH. Hold for 2 seconds to activate EMERGENCY mode.

How do I adjust volume/WPM?

1. Press SEL to toggle VOL/WPM target
2. Use UP/DN to adjust value
3. Hold SEL for 1 second to save

How do I access the config portal?

1. Hold SEL for 3 seconds
2. Connect to AegisBeacon WiFi
3. Open http://192.168.4.1

How do I factory reset?

Hold both MODE and SEL buttons at boot for 5 seconds. Device reboots with default settings.

Troubleshooting

Device won’t boot

1. Check USB connection
2. Verify power supply
3. Try different USB cable
4. Press BOOT button during upload

Radio not transmitting

1. Verify BUSY pin (GPIO 21) connected
2. Check SPI connections
3. Test with SDR
4. Increase TX power

OLED not displaying

1. Check SPI connections
2. Verify 3.3V power
3. Test with simple sketch
4. Check reset pin (GPIO 4)

GPS not fixing

1. Move outdoors
2. Wait 5-15 minutes
3. Check UART2 connections
4. Verify GPS power

Community

How can I contribute?

1. Fork the repository
2. Create a feature branch
3. Submit a pull request

See Contributing to Aegis-Beacon for contribution guidelines.

Where can I get help?

• GitHub Issues: Report bugs or request features
• GitHub Discussions: Ask questions
• Wiki: Technical documentation

Can I use this commercially?

Yes, under the MIT license. See Contributing to Aegis-Beacon for licensing details.