Herelink and new french law about UAV digital signalisation


Now french operators of more than 800g weighted uavs need to have on board a signalisation device emitting some required data for law enforcement units.

It only consist of a classic wifi 802.11n frame broadcasted from air device on the 2400 – 2483.5Mhz band ( mostly channel 6 ) containing those data:

  • Frame Control fields:
  • Frame type : 0
  • Frame Subtype : 6
  • More Fragment : 0
  • Retry : 0

*Fields of frames after frame Control one needs:

  • Adress 1 : FF.FF.FF.FF (broadcast),
  • Adress 2 : mac Adress of the emitting device
  • Payload header is 15 bytes total containing:
  • protocol number, 2 bytes, value: 1.

  • protocol version, 1 byte, value: 1.

  • timestamp, 6 bytes YYYYMMDDHHMMSS

  • frame number, 2 bytes, Zeroed at uav power up.

  • mandatory data size , 2 bytes

  • optional data size: 2 bytes

Then the payload:

  • drone ID, 30 bytes containing those 3 fields:
    . Constructor trigram, 3 bytes
    . Uav model id or signalement device id: 3 bytes
    . Uav or signalement device serial number, 24 bytes
    ( in case of less than 24 characters zero ore placed at the front. )

  • UAV position when message is sent, 10 bytes containing:
    . Latitude, 4 bytes, first part sign bit (MSB) and it’s decimal, then exposant is index to 5.
    Then all data have 5 decimals: XXX.XXXXX
    . Longitude, 4 bytes, …
    . Altitude, 2 bytes, in meters, absolute from zero sea level.

  • takeoff position
    . Latitude
    . Longitude
    . Alt

  • Ground speed, 1 byte, m/s

  • Route, 2 bytes, 0° to 359°

Frame needs to be broadcasted every 3sec max and each 30 meters max.

Would it be possible to integrate this feature to Herelink natively?
For now we have to use some external signalisation device but it add some weight on board but would be legitimate to handle this from HL air unit directly if capable.



I guess you need the remote id?

I guess not :slight_smile:
I’ve made an esp8266 based one for now but would like to handle this from Herelink Air unit directly. It works on the same bands and seems to have the capability to forge 802.11 frames

I think you can’t let the Herelink do this. Air unit is not designed to broadcast messages.
Also, you can’t modify the protocol within Herelink system. It is possible to add more mavlink messages though.

Thanks for your answer.

On what I see inside he air unit, seem we have everything needed on board to do it, even the wireless chipset can forge and send 802.11 frame.
The question is more how sending this frame each 3 sec on channel 6 would interfere with normal HL transmissons.

However, that’s not something we can code on our side, it’s part of HL closed source so I’d like to have developpers pov on this.


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Not solve the problem with the transponder in the Orange Cube?

That is an ADS-B receiver I think, not an transponder.

You are true. Sorry.
ADS-B Carrier Board

The new ADS-B carrier boards overall footprint is identical to the standard versions and the main changes compared to the original carrier are as follows:

Integration of uAvonix ADS-B IN **Receiver** on Serial 5
Built-In ADS-B Antenna