vdlm2monitor service
====================

Monitors 'vdlm2dec' decoder data to support maintaining a VDL2 Ground Stations list.
A text file, originally built for 'MultiPSK' decoder, which holds the translation
of the VDL2 Ground Station address (hexadecimal number) to location information.
Since there is no public official VDL2 GS list, this service is a tool to support the
maintenance of a list with data gathered from the collaboration of aviation enthusiasts.

How it works
============
vdlm2monitor service forwards 'vdlm2dec' decoder data to 'https://vdl2info.net/' server.
Data is fetched when written to disk log file, specified in 'vdlm2dec' command line:
e.g. vdlm2dec -l ~/vdlm2dec/vdlm2dec.log(example disk log file path)

The server aggregates 'vdlm2dec' decoder program data from participating stations.
* As with other similar projects, if many stations participate the better the result will be.

* Monitors for "unknown" VDL2 Ground Station address in latest 'VDL2_Ground_Stations' list.
(regardless of the file version the station is using)

* Notifies the VDL2 GS list maintainer with the corresponding information,
  who does the "processing" in order to "resolve" the Ground Station location.

* Note that 'vdl2info.net' server also aggregates VDL2 decoded data from
  'MultiPSK' and 'dumpvdl2' decoder programs  for the same purpose.

Additionally
============
If participating station owner enables, server offers:

* web based 'Enriched log' live streaming with message filters;
shows detailed information of Aircraft, Airports, Ground and Alternate Ground stations,

* and a feature for owner to download the station's enriched log files; sets the Access Key.

Requirements
============
The program is compiled for 'ARMv7' Processors [RaspBerry Pi and CPU compatible Boards]
running a Debian derivative Operating System.

#*#  Since there is No 'vdlm2dec' log file rotation, IF the log file path is modified:
#*#  it is REQUIRED to Stop/Start the service, in order the service to use the new path.

Installation [requires root privileges]
============
#*#  IF 'sudo' is not permitted to your user account switch to root user First

Step 1: Download and install vdlm2monitor service
======
$ bash -c "$(wget -q -O - https://vdl2info.net/updown/Decoders/m2dec.sh)"

Step 2: Configure the vdlm2monitor participation requirements
======
$ sudo nano /etc/default/vdlm2monitor

Step 3: Setup cooperation of vdlm2dec with vdlm2monitor service
======
IF not already, configure a disk log file output option as bellow
vdlm2dec -l ~/vdlm2dec/vdlm2dec.log(example disk log file path)

[restart vdlm2dec] -> [check vdlm2dec restarted normally]

Final step: Setup the service operation
==========
[Start -> Status: check for issues] -> [Set service permanent]

Start the service
=================
$ sudo systemctl start vdlm2monitor

Service status
==============
$ systemctl -l -n 100 status vdlm2monitor | more

Stop the service
================
$ sudo systemctl stop vdlm2monitor

Set the service permanent
=========================
$ sudo systemctl enable vdlm2monitor

#*#  Caution: After this step, on a runtime error, service will Automatically be Restarted.
#*#           To resolve any runtime issue:
#*#  Stop the service, check the service status for guidance, fix it and Start again.

Clear the service permanent flag
================================
$ sudo systemctl disable vdlm2monitor

UNinstallation [requires root privileges]
==============
#*#  IF 'sudo' is not permitted to your user account switch to root user First

$ cd ~
$ vdlm2monitor/uninstall.sh
$ rm -rf vdlm2monitor/

References
==========
'dumpvdl2' by Tomasz Lemiech  <https://github.com/szpajder/dumpvdl2>
'MultiPSK' by Patrick Lindecker  <http://f6cte.free.fr/index_anglais.htm>
'vdlm2dec' by Thierry Leconte  <https://github.com/TLeconte/vdlm2dec>

Watch for useful information: 'acars-vdl2 group' <https://acars-vdl2.groups.io/g/main>

verion 0.4beta (March 2024)
Written by Dimitris Georgiou