SoftRF, T-Beam and FLARM transmit

To transmit and receive FLARM-compatible signals in Europe, plug a T-Beam or T-Echo running Moshe Braner's SoftRF fork into Stratux over USB. Add one 1090 MHz SDR for ADS-B. Stratux detects the SoftRF device, takes GPS and traffic from it, and sets your aircraft type and address on it.

This guide builds on Stratux in Europe (FLARM and OGN).

What you need

  • A Stratux on the v2.0 image or later. Get it from the Download page.
  • One RTL-SDR for 1090 MHz.
  • A T-Echo, or a standard T-Beam, flashed with the Braner fork of SoftRF.
  • A USB cable from the device to the Pi.

With these, one 1090 SDR plus the SoftRF device covers FLARM and ADS-L in Europe.

Choosing the hardware

Item Guidance
T-Echo Has a good built-in GPS and needs no battery.
T-Beam Choose the u-blox GPS variant, not the L76K. Only the standard T-Beam is officially supported.
T-Beam Supreme (S3) Some people report it works, but support isn't guaranteed.
Band Buy the 868 MHz version for Europe. 915 MHz is for North America. A dual-band sticker on some boards isn't reliable.

How Stratux works with SoftRF

  1. Stratux detects SoftRF from its heartbeat on the USB serial connection.
  2. It reads GPS position and FLARM, OGN, FANET and ADS-L traffic from the device's NMEA output.
  3. It writes your aircraft type, address and address type to the device and saves them there.

When a SoftRF device is connected, a Tracker Configuration panel appears in Settings. Set the aircraft type and address there, then press Configure Tracker. If the device has only just powered up, give it a moment and refresh the page.

  • Set the primary protocol to Latest and the secondary to ADS-L.
  • Set the ICAO address of your aircraft. Without it, your aircraft can show up as two separate targets.
  • Stratux filters out primary/secondary combinations it doesn't support.

Limits

  • Stratux's Settings page doesn't expose every SoftRF option. Others, such as relay, have to be set on the SoftRF device itself.
  • Whether the Braner fork can receive FLARM and ADS-L at the same time is unsettled. If you need more than one protocol, an extra SDR can cover the rest.
  • Don't treat ADS-L transmit as a certified conspicuity solution. See Legal and limitations.
  • The OGN-Tracker firmware shipped with Stratux handles OGN, ADS-L and FANET, but not FLARM. For FLARM you need SoftRF.
  • An experimental build that drives an SX1262 radio module directly from the Pi exists, but it is not in the main release. Use a T-Beam or T-Echo.

Converting a US build for Europe

  1. The red UAT radio can't receive FLARM or OGN, so don't try to reuse it. 868 MHz needs an RTL-SDR.
  2. Add an RTL-SDR and an 868 MHz antenna. See Antennas.
  3. In v2.0 pre-releases, an SDR set up for 978 can be switched to 868 by disabling 978 and enabling OGN. The setup asks for your region.
  4. Add the SoftRF device for FLARM transmit.

OGN decoding needs a GPS fix. If OGN shows as disconnected, check GPS troubleshooting first.

Get help

Ask in the Discord.