ACARS decoder for rtl-sdr

friedtj friedtj at
Wed Aug 22 06:37:42 UTC 2012

I have just uploaded to

the first version of the ACARS message decoder I have written for gnuradio operating with
RTL-compatible dongles. I have included an example directory with a WAV file for testing the
decoder, and the log of last night's reception.
The decoder is far from perfect, but I think it behaves no worse than the sound-card based 
decoder I have used (e.g kracars and wacars). It is also, to the best of my knowledge, the
only opensource ACARS decoder since acarsdec does not seem functional (at least not with the
provided example file), so someone might find it useful, and maybe even inspiring for

I hope to learn by next week to add parameter passing from grc to the C++ program so that
two parameters -- the log file which is currently hardcoded to be located in /tmp/log_file.txt,
and a threshold value which is currently hardcoded but should be user-tunable (or ideally
automagically adapted to received power levels, but so far such attempts have failed) -- can be
provided through the gnuradio-companion interface. This will provide a minor update of the archive.

This is my very first attempt at grc block programming, so any feedback is welcome. I have
updated the manuscript describing the development method -- still in French unfortunately,
hoping to translate to English sometimes in the coming month -- and uploaded the PDF
document at for any French speaking audience to comment on.


JM Friedt, FEMTO-ST Time & Frequency/SENSeOR, 32 av. observatoire, 25044 Besancon, France

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