Need help decoding of FLARM (868.2/868.4MHz)

Nick Foster bistromath at
Fri Dec 6 16:14:14 UTC 2013

This is a new one! Thanks for bringing it to my attention. Looks like a
voluntary, GPS-based (i.e., not secondary surveillance) system. While the
serial protocol appears to be NMEA-like, the protocol "under the hood" at
the PHY layer could be basically anything, and the FLARM consortium appears
to have elected to keep specs hidden. Reading the dataport specification
gives few insights as to the PHY layer, but at least it's good to know the
protocol has "future-proof" support for all aircraft types.

[image: Inline image 1]

If you record good FLARM transmissions I am happy to assist in decoding
what I can, not least because proprietary protocols were meant to be open.


On Fri, Dec 6, 2013 at 7:58 AM, Fritz Meier <fritz.meier at> wrote:

> Hi, to all
> after I've seen with RTL ADSB and DUMP1090 how ADS-B transponder data
> 1090MHz (pulse modulation) is decoded I would like to start with FLARM
> (Europe 868.2 and 868.4MHz frequency modulated). The position data of
> gliders
> (ID, latitude, longitude and altitude) are sent 1xsec in the form of
> NMEA-like records.
> I work with the BeagleBone black and have a FLARM transmitter installed
> near
> the RTL-Dongle/Antenne and may at any time start recording I/Qsamples with
> Thanks
> Fritz
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