ACARS decoder / News: Recent posts

Acarsdec 3.3

Acarsdec 3.3 is now available on github :

  • simplify and improve internal PLL
  • add a "monitoring mode" which shows only the last aircrafts received

It will be probably the last version of acarsdec. (at least if there is no big bugs )

Posted by Thierry Leconte 2016-12-26

Acarsdec developpement now on github

acarsdec sources will now be on github :

Posted by Thierry Leconte 2016-10-23

2Ms/s vs 2.5Ms/s samping frequency

Note :
3.2 version of acarsdec use 2.5Ms/s sampling frequencies for rtl dongle and airspy sdr.

  1. It seems that some rtl dongle have problems with such a sampling rate. If you want to go back to 2Ms/s just change in rtl.c the #define RTLMULT : set it to 160 insteed of 200 and recompile
  2. If you want to experiment with 10Ms/s sampling with airspy, change in air.c the #define AIRMULT ; set it to 1600 insteed of 400. You muste have a porwerfull CPU and good USB to try that.
Posted by Thierry Leconte 2015-11-01

Acarsdec/acarsserv 3.2 released

Change log :
- refactor code to be more vector coprocessor (ss2 vpf4 ,..) friendly and fix internal sample frequency
- increase sample frequency to 2.5Mhz
- add support to airspy SDR ( frontend
- remove .wav input

No change to acarsserv

Posted by Thierry Leconte 2015-10-10

Acarsdec/acarserv 3.1 released

Fix release

Fix 2 annoying bugs :
- wrong variable type in acarsserv
- add station id name length check

  • change internal resampling frequency.
Posted by Thierry Leconte 2015-07-07

Acarsdec/acarserv 3.0 released

In this new major release, acarsdec comes with a database back-end program : acarsserv
acarsserv listens to acars messages on UDP coming from one or more acarsdec processes and store them in a sqlite3 database for latter analysis.

Change in acarsdec are minors :
- fix uplink/downlink message filter
- fix IPV6 addresses in -N -n options
- add the possibility to name rtl dongle by their S/N in -r option
- indent code
- small change in rtl code... read more

Posted by Thierry Leconte 2014-07-19

acarsdec 2.4 released

This his a minor fix release

Add :
A new option (-N) to send messages via UDP in its own acarsdec format

Fix :
- No CRLF in message text part in UDP packets sent in PP format
- -a option parsing (thanks to sv1ljj for the fix)
- remove scheduling setting code that lead to strange behaviours on some arm boards

Posted by Thierry Leconte 2014-05-29

acarsdec 2.3 released

I finally found what goes wrong with 2.2
In fact the problem was only with too slow CPU.
I removed most of the multithreading that hurts more than it helps on slow mono processor and switch to asynchronous IO.

Hope that this version will be the good one.
No features added since 2.2

Posted by Thierry Leconte 2014-04-07

acarsdec 2.2 removed

Seems that there is some big problem with the new 2.2 rtl front end : works with some frequencies configuration and not with others ..
2.1 must be fine but without the promised 2.2 added features and improvements ...

Sorry for that.

Posted by Thierry Leconte 2014-03-26

acarsdec 2.2 released

Yet another release, but this one must be the good one(TM)

Added Features:
- Could send ACARS messages over internet via UDP in planeplotter format

Improvements :
- Better and less CPU hungry rtl AM demod. Could now demod four frequencies on RaspberryPI with less than 30% CPU.
- Improved error correction

Fixes :
- lots of stupid bugs fixes...

Posted by Thierry Leconte 2014-03-23

acarsdec and raspberry PI

David Taylor (GM8ARV) have an interesting page about compiling acarsdec for raspberryPI :

acarsdec 2.1 is able to receive two acars frequencies simultaneously on raspberry PI.

I work on optimizations to be able to do better

Posted by Thierry Leconte 2014-03-09

acarsdec 2.1 released

This is a fix and small improvements release

  • Fix display of uplink messages

  • add -A option to display only downlink messages

  • add -g gain option to set rtl dongle preamp gain
  • add -p ppm to set ppm frequency correction for rtl dongle

  • improve -o 0 output (now print the beginning of message )

  • use sse2 optimized vector math lib for AM demod (more than 40% CPU load improvement)
  • other small performance optimizations
Posted by Thierry Leconte 2014-03-01

acarsdec 2.0 released

Acarsdec is a multi-channels acars decoder with built-in rtl_sdr front end.

The 2.0 version is a complete rewrite, very few code line remains from 1.x

Features :

  • new and improved msk demodulator
  • up to four channels decoded simultaneously
  • multi-threaded
  • error detection AND correction (correct all one error and some two errors)
  • input from sound file (.wav) , alsa sound card or software defined radio (SRD) via a rtl dongle (http://sdr.osmocom
    .org) ... read more
Posted by Thierry Leconte 2014-02-23

acarsdec 1.0 released

Acarsdec is an open source, realtime ACARS demodulator and position decoder for Linux.

Aircraft Communication Addressing and Reporting System (or ACARS) is a digital datalink system for transmission of small messages between aircraft and ground stations via VHF radio.

Audio output from air band VHF receiver is send to the soundcard input of your PC under Linux.
Then, acarsdec will demodulate the signals sent by aircrafts and print the received messages on its standart output or acts as a basic APRS server to feed xastir map plotting programm... read more

Posted by Thierry Leconte 2007-04-15

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