VDLM2DEC

vdlm2dec is a vdl mode 2 decoder with built-in rtl_sdr or airspy front end.

It could decode up to 8 frequencies simultaneously ( but in the same 2Mhz range )

Usage

vdlm2dec [-l logfile] [-g gain] [-r rtldevicenumber] Frequencies(Mhz)

-r rtldevicenumber : decode from rtl dongle number rtldevicenumber (don't set it for airspy)

-g gain : set preamp gain in tenth of db (ie -g 90 for +9db)

-p ppm : set rtl sdr ppm frequency (rtl_sdr only)

-q : quiet

-l logfile : output log (stderr by default)

-J : json output

-j addr:port send to addr:port UDP packets in json that could be read by acarsserv

Examples

./vdlm2dec -r 0 136.725 136.775 136.975

[#3 (F:136.975 P:-4.9) 26/01/2018 21:37:08.327 --------------------------------
Response from Aircraft: 440030 to 1098CA 
Frame-S: Nr:5 SREJ

[#3 (F:136.975 P:-4.0) 26/01/2018 21:37:08.575 --------------------------------
Command from Aircraft: 400D8D to 1098AA 
Frame-U: XID
Connection management: HO|VDA|ESN
XID sequencing 0:0
Specific options: GDA:ESN:IHS:BHN:BCN
Destination airport EGMC
Aircraft Position 45.8  -0.3 alt: 38000

[#3 (F:136.975 P:-7.2) 26/01/2018 21:39:31.155 --------------------------------
Command from Aircraft: 440575 to 213C97 
Frame-I: Ns:3 Nr:7
ACARS
Aircraft reg: OE-IAP Flight id: 3V0015
Mode: 2 Msg. label: 85
Block id: 1 Ack: !
Msg. no: M29A
Message :
3C01 POSWX0015/180126/LEZL/EBLG/OE-IAP
/POS46.36917/0.1911/OVR2139
/ALT33592/FOB0019/MCH770.000000/SAT

Compilation

vdlm2dec must compile directly on any modern Linux distrib. It has been tested on x86_64 with fedora 27, on tegra with Ubuntu 14.04.5

It depends on some external libraries :

librtlsdr for software radio rtl dongle input (http://sdr.osmocom.org/trac/wiki/rtl-sdr)
libusb

make -f Makefile.rtl for rtl-sdr

make -f Makefile.air for airspy

Frequency correction for rtl-sdr

when receiving a message ex : [#1 (F:136.725 P:-3.7) 26/01/2018 21:34:57.633 -------------------------------- read the ppm displayed in P: field.
Guess an average, round to near integer
set the -p option as the opposite of this number (ex : -p 4 )

Acarsserv

acarsserv is a companion program for vdlm2dec. It listens to acars messages on UDP coming from one or more acarsdec processes and stores them in a sqlite database.

See : acarsserv

Note : vdlm2dec could only send packet over the network on json format. It does not support the acarsdec old binary format.

Copyrights

These code are free software; you can redistribute it and/or modify it under the terms of the GNU Library General Public License version 2 published by the Free Software Foundation.

dev-zzo / vdlm2dec