SoftRF Firmware Guide
What is SoftRF?
SoftRF is an open-source firmware project that enables DIY aviation tracking devices using affordable off-the-shelf hardware. The most popular implementation uses the TTGO T-Beam, an ESP32-based board with integrated LoRa radio, GPS, and battery management.
When loaded with SoftRF or OGN Tracker firmware, a T-Beam can transmit FLARM-compatible signals on 868 MHz (Europe) or 915 MHz (US/Australia), making your aircraft visible to other FLARM receivers and on the Open Glider Network (OGN).
TTGO T-Beam Hardware
T-Motion: Compact Alternative
The TTGO T-Motion (SoftRF Dongle Edition) is an ultra-compact USB-stick form factor alternative to the T-Beam. Ideal for space-constrained installations or as a dedicated low-power transmitter.
T-Motion Specifications
T-Beam vs T-Motion
| Aspect | T-Beam | T-Motion |
|---|---|---|
| Form Factor | Development board | USB stick (3-4× smaller) |
| GPS Receiver | u-blox NEO-M8N (high precision) | Sony CXD5603GF |
| Power | ~160-280 mA | ~18 mA (10× less) |
| Battery | 18650 holder built-in | None (USB powered) |
| WiFi/Bluetooth | Yes (ESP32) | No |
| Barometer | Optional (add BMP280) | None (external BMP280 recommended) |
| Stratux Connection | USB or UART wiring | Direct USB plug-in |
| Best For | Full-featured DIY builds | Simple plug & play TX |
Wiring & Integration
USB Direct (Recommended)Recommended
Plug T-Motion directly into Raspberry Pi USB port. Stratux auto-detects the device. No wiring required.
Pi USB ← T-Motion USB-A
UART Serial (Advanced)
For custom integrations, T-Motion exposes 3.3V UART pins (38400 baud, 8N1). Connect TX→RX, RX→TX, GND→GND.
T-Motion TX → Pi RX (GPIO 15) T-Motion RX → Pi TX (GPIO 14) T-Motion GND → Pi GND
💡 For pressure altitude reporting, add an external BMP280 sensor via I²C. See guides: T-Motion altitude sensor or T-Beam pressure sensor.
SX1276 vs SX1262: LoRa Chip Comparison
T-Beam modules come with different LoRa radio chips. The SX1262 is the newer generation with better efficiency, though both work well for aviation use.
| Aspect | SX1276 | SX1262 |
|---|---|---|
| Generation | Gen 1 (2013) | Gen 2 (2018) |
| TX Power | Up to +20 dBm | Up to +22 dBm (better PA) |
| RX Sensitivity | -137 to -142 dBm | Up to -148 dBm |
| Power Draw (RX) | ~10-11 mA | ~4.6 mA (50% less) |
| Firmware Support | Fully supported (most common) | Supported (verify version) |
| Availability | T-Beam v1.0, v1.1 | T-Beam Supreme, newer |
| Best For | Maximum compatibility | Battery-powered setups |
Firmware Options
SoftRF
The original open-source firmware supporting multiple protocols (FLARM, OGN, FANET, ADS-L). Highly configurable with web interface.
GitHubOGN Tracker
Dedicated OGN firmware optimized for glider tracking. Simpler configuration, focused on OGN network participation.
GitHubNative OGN (Stratux Direct)Recommended
Flash OGN firmware directly from Stratux. Enables parallel TX of ADS-L, OGNTP, FANET, and PilotAware protocols-the most versatile multi-protocol option.
GitHubGXAirComRecommended
Alternative firmware focused on FLARM and FANET protocols. Provides native FLARM TX/RX compatibility with additional FANET messaging support.
GitHubStratux EU (T-Beam Mode)
Stratux firmware can directly interface with T-Beam modules connected via serial, using them as OGN transmitters while Stratux handles reception.
GitHubProtocol Support Matrix
When using T-Beam with Stratux, only TX (transmit) capabilities matter-Stratux receives all protocols via its dual SDR receivers. The RX column is only relevant for standalone T-Beam use.
| Firmware | FLARM | OGNTP | FANET | ADS-L | PilotAware | GPS | Notes |
|---|---|---|---|---|---|---|---|
| SoftRF | RX: 1TX: 1 | RX: 1TX: 1 | RX: 1TX: 1 | RX: 1TX: 1 | 1 Hz | Single protocol only-choose one for RX and TX | |
| OGN-Tracker | RX: ✓TX: ✓ | RX: -TX: ✓ | RX: -TX: ✓ | RX: -TX: ✓ | 5 Hz | TX: All 4 protocols in parallel (simultaneously) | |
| GXAirCom | RX: ✓TX: ✓ | RX: ✓TX: ✓ | 5 Hz | TX: FLARM & FANET in parallel (simultaneously) |
Stratux Dongle Protocol Switching
The Stratux Dongle (T-Motion based) can only transmit ONE protocol at a time. Unlike the Stratux Pro which transmits all protocols simultaneously, you must manually select which protocol to activate via the web interface.
Available TX Protocols
Open Glider Network protocol. Best for visibility on OGN live tracking and ground stations.
Flying Ad-hoc Network. Popular in paragliding/hang gliding communities. Includes messaging capabilities.
UK-focused protocol with strong general aviation adoption. Good for UK/Ireland operations.
FLARM-compatible legacy protocol for visibility to certified FLARM devices.
Note: ADS-L is NOT available on the Dongle. For ADS-L transmission, upgrade to Stratux Pro or Stratux Dual Pro.
How to Switch Protocols
- Connect to your Stratux WiFi network
- Open the web interface at 192.168.10.1
- Navigate to Settings → Transmitter
- Select your desired protocol from the dropdown
- Click Save and wait for the device to restart
💡 For most European pilots, we recommend OGN (OGNTP) as the default protocol. It provides the widest ground station coverage and integrates with popular tracking platforms like glidertracker.org and live.glidernet.org.
Need simultaneous multi-protocol TX? The Stratux Pro and Dual Pro transmit all 5 protocols in parallel-no switching required.
GPS Update Rate & AHRS Performance
The T-Beam's GPS update rate significantly impacts AHRS (Attitude and Heading Reference System) performance when connected to Stratux. This is especially critical during flight-ground testing won't reveal the difference.
1 HzPoor
SoftRF
Updates position once per second. Static GPS configuration. Insufficient for smooth AHRS-causes jerky attitude display and lag during maneuvers.
5 HzGood
OGN-Tracker / GXAirCom
Updates position 5 times per second. Configurable to use GPS+GLONASS+Galileo+SBAS. Provides smooth, responsive synthetic vision with minimal lag.
Important: You cannot verify GPS/AHRS performance on the ground. On the ground, all firmware looks fine. The difference only becomes apparent in flight during dynamic maneuvers where 1Hz GPS causes noticeable AHRS lag.
💡 For Stratux integration, we strongly recommend OGN-Tracker or GXAirCom firmware for proper AHRS functionality.
T-Beam Integration with Stratux
T-Beam runs independently with SoftRF or GXAirCom firmware, transmitting position and receiving nearby traffic. Can output to EFB via WiFi/Bluetooth.
T-Beam connected to Stratux via serial (UART). Stratux provides position data, T-Beam handles transmission. Best of both worlds: SDR reception + T-Beam OGN TX.
Our Stratux Pro and Dual Pro models include pre-integrated T-Beam module(s) for plug-and-play OGN transmission. No configuration needed.
SoftRF vs Native FLARM
| Aspect | SoftRF/T-Beam | Native FLARM |
|---|---|---|
| Protocol | Compatible with FLARM/OGN (decodes legacy FLARM) | Proprietary encrypted protocol |
| Certification | Not certified - experimental/recreational use | Certified for all operations |
| Cost | ~€30-50 for T-Beam hardware | €500-2000+ for certified devices |
| Range | Typically 5-15 km (antenna dependent) | Similar range with optimized antennas |
| OGN Visibility | Yes - native OGN protocol support | Yes - via ground stations |
Legal Considerations
SoftRF and T-Beam devices transmit on ISM bands (868/915 MHz) which are license-free in most countries. However, note that: (1) These are NOT certified collision avoidance devices and should not be relied upon as primary safety equipment. (2) FLARM protocol transmission may have licensing implications in some jurisdictions-check local regulations. (3) For soaring competitions, official FLARM devices may be required. (4) Always register your device with OGN to avoid being flagged as an unidentified target.
Frequently Asked Questions
Related Technology Guides
Get Stratux with T-Beam Integration
Our Stratux Pro and Dual Pro include pre-configured T-Beam modules for OGN transmission. No soldering or firmware flashing required.
Disclaimer
Stratux is not certified aviation equipment. It does not replace a transponder or relieve the pilot of traffic awareness responsibilities. Use as supplementary situational awareness only. Dross:Aviation assumes no responsibility or liability for the use of Stratux devices, firmware flashing, or hardware modifications. All DIY guides are provided without warranty-use at your own risk.