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YOU CAN BUILD THE BEACON THAT TELLS OTHER AIRCRAFT WHERE YOU ARE

A credit-card-sized radio that tells nearby aircraft where you are, built from GNSS, a sub-1 GHz transceiver and a barometer.

by Linar Yusupov

FULL CAD BOM FIRMWARE DOCS

Open-hardwareElectronics

Built withESP323D printing

difficulty
●●●●○
time
a weekend-plus
license
GPL-3.0
repo
repo ACTIVE1,025 stars

WHAT YOU’LL NEED

1
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COMPAREE VERDICT

Most current editions are ready-made LoRa boards you buy and flash: the Badge is a LilyGO T-Echo with an e-paper screen, the Card a Seeed SenseCAP tracker, the Pocket an Elecrow ThinkNode M3 and the Prime a LilyGO T-Beam — nRF52840 or ESP32 with SX1262/LR2021 radios and GNSS on board. The firmware is actively maintained, with frequent releases.

GOOD TO KNOW

  • —GPL-3.0 licence, permits commercial use.
  • —Not one board but a family: Card, Badge, Pocket, Prime and several more — current editions run on ready-made boards (LilyGO T-Echo, LilyGO T-Beam, Seeed SenseCAP tracker, Elecrow ThinkNode M3) that you buy and flash; each edition has its own wiki page.
  • —Prebuilt firmware binaries are provided; building from source uses the Arduino IDE, with targets including ESP32, nRF52840, RP2040, STM32 and more depending on edition.
  • —The wiki is comprehensive but assumes you know what FLARM and OGNTP are — there is no beginner guide to the aviation protocols themselves.
  • —Not certified avionics: it is an awareness aid, not a certified anti-collision system. Several editions' hardware does carry CE/FCC radio certification.
  • —Radio transmission on sub-1 GHz ISM bands is regulated — what is legal in Europe may not be in the US or elsewhere.

Parts to buy

3 items

From our check of the build. Exact quantities and part numbers are in the creator’s BOM.

  • Commercial board for your chosen editionFind
  • Battery if not includedFind
  • Optional printed caseFind

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Can I build this?

Printenclosures available for some editions, not required
BuyThe commercial board for your chosen edition, a battery if not included, optional printed case
ToolsA computer to flash the firmware, GNSS-capable test location for initial setup, aviation navigation app (XCsoar, OGN Tracker, etc.)
SkillsFirmware flashing (often drag-and-drop UF2), configuration, and reading the aviation protocol and regulatory docs
TimeAn evening to flash and configure the board, another half-day minimum for protocol research and regulatory checks before first flight
Cost$$ — mostly the ready-made board for your edition; the wiki puts the Card Mark III board (Seeed SenseCAP MeshTracker X1) at 40-plus dollars.
SafetyLithium battery — standard precautions. The bigger risk is regulatory: radio transmission rules differ by country, so verify that the band and power you use are legal where you fly before powering on.

Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.

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Gallery

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Start here

Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.

  1. 1.Read the main wiki page to understand the editions and pick one (The Badge has its own e-paper screen, Card and Pocket are the smallest units, the Prime has higher transmit power — each runs on a different ready-made board.)
  2. 2.Check the legal status of sub-1 GHz ISM transmission where you fly(Europe, US, Australia and other jurisdictions have different rules — this step comes before ordering parts.)
  3. 3.Open your chosen edition's wiki page (It names the ready-made board the edition runs on and how to flash it.)
  4. 4.Buy the board for your edition from the manufacturer(Manufacturers change components between batches — check the edition page before ordering.)
  5. 5.Flash the SoftRF firmware (UF2/esptool per the wiki) and test the GNSS fix outdoors(Initial setup needs a working GNSS fix — an outdoor test location is faster.)

KNOWN ISSUES

  • Buying the wrong board revision — manufacturers change components between batches; check the edition page before ordering.
  • Assuming sub-1 GHz ISM transmission is universally legal — it is not. What is permitted in Europe may be restricted or illegal in the US, Australia or elsewhere. Check your local regulations before the first power-on.
  • Skipping the protocol research — the wiki assumes you know what FLARM, OGNTP and the traffic protocols are. If you do not, budget half a day reading the specs or you will not understand what the unit is actually transmitting.
  • Expecting certified anti-collision performance — this is an awareness aid, not certified avionics (CE/FCC radio approval of some editions is not the same thing). It is not a substitute for see-and-avoid, and the author warns that 'compatible' is not 'fully compatible' with commercial systems.
  • Mounting a lithium battery in a hot cockpit without ventilation — summer cockpit temperatures can exceed safe lithium charging and storage limits. Use a vented enclosure or remove the battery when parked in sun.
  • Not testing the traffic display integration before the first flight — pairing with XCsoar, OGN Tracker or similar apps can be finicky. Verify the connection on the ground, not at altitude.

Which edition should I build?

Badge (LilyGO T-Echo, with e-paper screen) if you want a standalone wearable with its own display; Card (Seeed tracker) or Pocket (ThinkNode M3) for the smallest units that stream traffic to a tablet; Prime (LilyGO T-Beam) for higher transmit power. Compare the edition wiki pages.

Will this work with the FLARM box already in my club glider?

SoftRF lists the FLARM AIR V7 radio protocol as compatible, along with OGN, PilotAware (P3I) and FANET+. The author stresses that 'compatible' is not 'fully compatible' — only a reasonable minimum of each protocol is implemented — so test with your club's units on the ground before relying on it.

Do I need a pilot licence to build or use this?

No licence is required to build it. Operating a radio transmitter in flight is subject to aviation and radio regulations that vary by country — you are responsible for checking what is legal where you fly.

Can I use this for FPV drones or RC aircraft?

Yes, there are editions for that: the UAV Edition (first introduced in 2017) links to the autopilot over MAVLink and passes received traffic to ADS-B-capable autopilots such as Pixhawk, and the wiki points to the newer Nano Edition as the more advanced design. Check your local drone and radio rules first.

What is the transmit range?

It depends on the edition, its transmit power, the antenna and terrain. Check your edition's wiki page (for example the Antennas section of Prime Mark IV) and test range on the ground with another unit.

Community builds

No community builds yet — be the first, we feature the best ones.

Discussion1

FROM THE COMPAREE TEAM

The project wiki lists Card, Badge, Pocket and Prime editions, plus several more experimental variants — each with different size, power and display trade-offs. Which would you build for your aircraft, and what decided it?

CompareeTEAM1mo agoedited

Practical notes from our verification: the repository is actively maintained (last push October 2026) and licensed GPL-3.0. Most current editions are built on ready-made partner hardware rather than a board you assemble yourself: the Badge Edition runs on a LilyGO T-Echo, Prime Edition Mark IV on a LilyGO T-Beam 1W LR2021, Card Mark III on a Seeed SenseCAP MeshTracker X1, and the Pocket Edition on an Elecrow ThinkNode M3. Each edition has its own wiki page, so pick the edition first and follow that page. The biggest non-technical hurdle is regulatory: sub-1 GHz ISM transmission rules differ between Europe, the US and other regions, so check what applies where you fly. Correction (4 October 2026): we re-checked this page line by line against the project's own repository, documentation and videos, and fixed errors in earlier versions.

Linar Yusupov

Linar Yusupov started SoftRF in 2015 as a DIY, open-source proximity awareness system for general aviation, and has since ported it to a long list of editions built on boards from LilyGO, Seeed, Elecrow, Heltec and other makers.

GitHub

Star the project on GitHub

DISCLAIMER

  • Comparee is not the author of the projects featured here. All rights to each project belong to its creator — every page links to the original source, and we never host creators’ files.
  • Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
  • Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
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