Receiving ACARS messages with a software-defined radio on a Mac

From the archive: how I compiled rtl_acars on OS X 10.9 Mavericks and received my first aircraft messages with an RTL-SDR dongle.

NoteFrom the archive

First published on my old blog in September 2014 as Compiling and installing rtl_acars on OS X 10.9 Mavericks. These steps are for a 2014 system and are very likely out of date: the software, the build tools and macOS itself have all changed since. I keep the post for the fun of it.

I struggled for a while, but in the end I managed to install rtl_acars on my Mac, and after some hours of waiting I received my first ACARS messages. ACARS is the short-message system that aircraft use to talk to ground stations. Now it is only a matter of building a better antenna. Here is my path to success.

# Clone 9nut's version of rtl-sdr from GitHub
git clone https://github.com/9nut/rtl-sdr

# Add missing lines in Makefile.am
rtl_acars_SOURCES = rtl_acars.c
rtl_acars_LDADD = librtlsdr.la $(LIBM)

# I had previously installed Homebrew to get the necessary libraries
brew install libtool
aclocal
glibtoolize
autoconf
automake --add-missing

# Choose your own destination
./configure --prefix=/Users/user/rtl/
make
make install

And my first received ACARS message came from a United Airlines plane:

RX_IDX: 0
ACARS mode: V, message label: H1
Aircraft reg: .N14121, flight id: UA0069
Block id: 55, msg. no: D02A
Message content:-
#DFBCL2N14121ESSAKEWR3008072336 222 -075-215 20028064524168000691CLMBB
349 031887031259 961 963 899 904 906 903708702 8480 8512168616890310
85065008080040